Journal articles on the topic 'Embryonic Structures physiology'
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KIMURA, HIROSHI, IKUO TOHYAMA, KOUNOSUKE MIZUTANI, and JUNZO OCHI. "Fibronectin-like immunoreactive structures in embryonic rat brain." Acta Histochemica et Cytochemica 22, no. 2 (1989): 243–58. http://dx.doi.org/10.1267/ahc.22.243.
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POLUEKTOV, M. G., and P. V. PCHELINA. "SLEEP IN CHILDREN: FROM PHYSIOLOGY TO PATHOLOGY." Medical Council, no. 9 (July 18, 2017): 97–102. http://dx.doi.org/10.21518/2079-701x-2017-9-97-102.
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Circadian rhythms and the mechanisms of sleep and wakefulness begin to form in the embryonic period and undergo many stages of development before acquire characteristics typical for an adult. Structure of sleep disturbances in children also differs from that in the adult population. Most sleep disorders in children are the result of immaturity of certain brain structures and mechanisms: primary sleep disorders, pediatric behavioral insomnia, sleepwalking, night terrors, enuresis. These disorders are benign, and usually disappear by adulthood. Treatment of benign sleep disorders in children should primarily be based on the methods of behavioral therapy, the rules of sleep hygiene and the purpose of light sedation.
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Jacobson, A. G., and A. K. Sater. "Features of embryonic induction." Development 104, no. 3 (November 1, 1988): 341–59. http://dx.doi.org/10.1242/dev.104.3.341.
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The patterned distribution of different organs in the amphibian embryo begins with the establishment of two domains, the animal and vegetal regions, that differ in developmental potency. Differences amplify as inductive interactions occur across boundaries between areas of different potency. Embryonic induction establishes a temporally and spatially dynamic area of developmental potency - a morphogenetic field. The final arrangement and differentiation of cell types within the field emerge from subsequent interactions occurring primarily within the field. These principles are illustrated in a review of the induction of the lens and the heart. Recent studies show that the induction of the lens of the eye and the induction of the heart begin early in development. Most of lens inductions occurs before the formation of the optic vesicle, and the heart appears to be part of a complex of dorsal structures whose formation is dependent upon the establishment of the dorsoventral axis. Suppressive as well as inductive tissue interactions occur during the determination of both of these organs, affecting their position and time of appearance. The complex processes of induction defined by the past nine decades of experimental work present many challenging questions that can now be addressed, especially in terms of the molecular events, cellular behaviour and regulatory physiology of the responding tissue.
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Yamamoto, Makoto, Li Cui, Kohei Johkura, Kazuhiko Asanuma, Yasumitsu Okouchi, Naoko Ogiwara, and Katsunori Sasaki. "Branching ducts similar to mesonephric ducts or ureteric buds in teratomas originating from mouse embryonic stem cells." American Journal of Physiology-Renal Physiology 290, no. 1 (January 2006): F52—F60. http://dx.doi.org/10.1152/ajprenal.00001.2004.
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Ureteric bud epithelial cells and metanephric mesenchymal cells that comprise the metanephric kidney primordium are capable of producing nephrons and collecting ducts through reciprocal inductive interaction. Once these cells are induced from pluripotent embryonic stem (ES) cells, they have the potential to become powerful tools in the regeneration of kidney tissues. In this study, we investigated these renal primordial cells and structures in mouse ES cell outgrowths and their transplants. Gene expression essential for early kidney development was examined by RT-PCR in embryoid body (EB) outgrowths and their transplants in adult mice. Histochemical detection of kidney primordial structures and gene expression analysis coupled with laser microdissection were performed in transplant tissues. RT-PCR analysis detected gene expression of Pax-2, Lim-1, c-Ret, Emx2, Sall1, WT-1, Eya-1, GDNF, and Wnt-4 in the EB outgrowths from days 6–9 of expansion onward, and also in the teratoma tissues 14 and 28 days after transplantation. Histochemical analysis 14 days after transplantation showed that some ducts were positive for Pax-2, endo A cytokeratin, kidney-specific cadherin, and Dolichos biflorus agglutinin and that dichotomous branching of these ducts had occurred. These staining patterns and morphological features are intrinsic for mesonephric ducts and ureteric buds. In long-term survival of 28 days, Pax-2-immunoreactivity disappeared in some renal primordia-like structures, indicating their differentiation. Some ducts were accompanied by mesonephric nephron-like convoluted tubules. RT-PCR analysis of those structures collected by microdissection confirmed that they expressed kidney development-related genes. In conclusion, these data suggest the potential of ES cells to produce renal primordial duct structures and provides an insight into the regeneration of kidney tissues.
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Antes, Lisa M., Monica M. Villar, Sylvia Decker, Roberto F. Nicosia, and Dean A. Kujubu. "A serum-free in vitro model of renal microvessel development." American Journal of Physiology-Renal Physiology 274, no. 6 (June 1, 1998): F1150—F1160. http://dx.doi.org/10.1152/ajprenal.1998.274.6.f1150.
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The differentiation and organization of the embryonic renal vasculature is a crucial event in renal development. To study this process, we developed a serum-free in vitro model of renal microvessel development. Mouse embryonic kidney explants, when embedded specifically in type I collagen, demonstrate outgrowth of microvascular structures when stimulated by the phorbol ester 12- O-tetradecanoylphorbol 13-acetate (TPA, 10–50 ng/ml). Other polypeptide growth factors stimulated little, if any, microvessel outgrowth from the explants. Similar outgrowths were not observed when other embryonic tissue explants were used. The number of microvessels observed depended on the gestational age of the explants. We hypothesize that TPA induces the in situ differentiation of metanephric mesenchymal cells into endothelial cell precursors and that specific matrix proteins and cell-matrix interactions are necessary for the organization of these precursors into microvessels. Our model will allow us to examine in detail the responsiveness of metanephric kidney cells to both growth factors and extracellular matrix molecules and to understand how they influence renal endothelial cell differentiation.
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Kuwahara, M., T. Ogaeri, R. Matsuura, H. Kogo, T. Fujimoto, and S. Torihashi. "In vitro organogenesis of gut-like structures from mouse embryonic stem cells." Neurogastroenterology and Motility 16, s1 (April 2004): 14–18. http://dx.doi.org/10.1111/j.1743-3150.2004.00468.x.
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Northcutt, R. Glenn. "The use and abuse of developmental data." Behavioral and Brain Sciences 26, no. 5 (October 2003): 565–66. http://dx.doi.org/10.1017/s0140525x03340129.
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Structural similarity is helpful in recognizing homologous structures, but it does not define them. Such structures must also have phylogenetic continuity, a criterion that is ignored by Aboitiz et al. and by proponents of “field homology.” “Similar” structures, as well as “field homologues” from “the same” embryonic field, are not necessarily homologous, and an outgroup analysis of developmental stages should be performed to establish homologies.
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Driehuis, Else, and Hans Clevers. "CRISPR/Cas 9 genome editing and its applications in organoids." American Journal of Physiology-Gastrointestinal and Liver Physiology 312, no. 3 (March 1, 2017): G257—G265. http://dx.doi.org/10.1152/ajpgi.00410.2016.
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Organoids are three-dimensional (3D) structures derived from adult or embryonic stem cells that maintain many structural and functional features of their respective organ. Recently, genome editing based on the bacterial defense mechanism CRISPR/Cas9 has emerged as an easily applicable and reliable laboratory tool. Combining organoids and CRISPR/Cas9 creates exciting new opportunities to study organ development and human disease in vitro. The potential applications of CRISPR in organoids are only beginning to be explored.
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Rungarunlert, S., W. Chakritbudsabong, S. Pamonsupornvichit, L. Sariya, R. Pronarkngver, S. Chaiwattanarungruengpaisan, J. N. Ferreira, et al. "184 Establishment of Porcine Induced Pluripotent Stem Cell Lines by Adding LIN 28 Transcription Factor." Reproduction, Fertility and Development 30, no. 1 (2018): 232. http://dx.doi.org/10.1071/rdv30n1ab184.
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The establishment of porcine induced pluripotent stem cells (piPSC) is important in the field of human biomedical regenerative medicine. The pig model is a more representative model than current rodent models because it better mimics human physiology in different organ systems. The piPSC can be traditionally generated by reprogramming somatic cells using 4 transcription factors (4TF: OCT4, SOX2, KLF4, and c-MYC), similarly in human. However, it is difficult to maintain the pluripotent state of reprogrammed cells and they exhibit poor differentiation capacity. Hence, the 4TF may be not enough to reprogram porcine somatic cells. This study aimed to establish piPSC by adding LIN28 (referred to as 5TF) to the traditional 4TF, via retroviral vector. Here, we report the successful establishment of 3 piPSC lines by using the 5TF. All 5TF-piPSC lines exhibited a normal karyotype (38, XY) and a typical mouse embryonic stem cell (ESC) morphology, including tightly packed and dome-like shape, even after they were propagated over 40 passages. All 5TF-piPSC lines were positive for alkaline phosphatase staining and expressed high levels of ESC-like markers (OCT4, SOX2, NANOG, and SSEA-1). Importantly, the 5TF-piPSC lines showed pluripotent capacity, as evidenced by differentiation into 3 germ layers in vitro following cystic embryoid body formation, as well as by efficiently forming teratomas containing all 3 embryonic germ layers in vivo. Moreover, the 5TF-piPSC lines showed spontaneously contractile cardiomyocytes and expressed cardiomyocyte markers (cardiac troponin T) during spontaneous cardiac differentiation using cell aggregation into spherical-like structures referred to as embryoid bodies. Thus, the addition of LIN28 TF promoted long-term pluripotency of piPSC and enhanced the ability to differentiate towards 3 embryonic germ layers and cardiac lineage. This research project is supported by grants from the Mahidol University, Thailand.
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Tkatchenko, Tatiana V., Ricardo A. Moreno-Rodriguez, Simon J. Conway, Jeffery D. Molkentin, Roger R. Markwald, and Andrei V. Tkatchenko. "Lack of periostin leads to suppression of Notch1 signaling and calcific aortic valve disease." Physiological Genomics 39, no. 3 (November 2009): 160–68. http://dx.doi.org/10.1152/physiolgenomics.00078.2009.
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The Postn gene encodes protein periostin. During embryonic development, it is highly expressed in the outflow tract (OFT) endocardial cushions of the developing heart, which give rise to several structures of the mature heart including the aortic valve. Periostin was previously implicated in osteoblast differentiation, cancer metastasis, and tooth and bone development, but its role in cardiac OFT development is unclear. To elucidate the role that periostin plays in the developing heart we analyzed cardiac OFT phenotype in mice after deletion of the Postn gene. We found that lack of periostin in the embryonic OFT leads to ectopic expression of the proosteogenic growth factor pleiotrophin ( Ptn) and overexpression of delta-like 1 homolog (Dlk1), a negative regulator of Notch1, in the distal (prevalvular) cushions of the OFT. This resulted in suppression of Notch1 signaling, strong induction of the central transcriptional regulator of osteoblast cell fate Runx2, upregulation of osteopontin and osteocalcin expression, and subsequent calcification of the aortic valve. Our data suggest that periostin represses a default osteogenic program in the OFT cushion mesenchyme and promotes differentiation along a fibrogenic lineage. Lack of periostin causes derepression of the osteogenic potential of OFT mesenchymal cells, calcium deposition, and calcific aortic valve disease. These results establish periostin as a key regulator of OFT endocardial cushion mesenchymal cell fate during embryonic development.
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Denham, Mark, Timothy J. Cole, and Richard Mollard. "Embryonic stem cells form glandular structures and express surfactant protein C following culture with dissociated fetal respiratory tissue." American Journal of Physiology-Lung Cellular and Molecular Physiology 290, no. 6 (June 2006): L1210—L1215. http://dx.doi.org/10.1152/ajplung.00427.2005.
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Mouse embryonic stem cells (MESCs) are pluripotent, theoretically immortal cells derived from the inner cell mass of developing blastocysts. The respiratory epithelium develops from the primitive foregut endoderm as a result of inductive morphogenetic interactions with the surrounding visceral mesoderm. After dissociation of the explanted fetal lung into single cells, these morphogenetic signaling pathways instruct reconstitution of the developing lung according to a process known as organotypic regeneration. Data presented here demonstrate that such fetal lung morphogenetic cues induce MESC derivatives to incorporate into the reforming pseudoglandular-like tubular ducts, display pan-keratin and surfactant protein C (Sftpc) immunoreactivity, and express Sftpc transcripts while displaying a normal diploid karyotype in coculture. The Sftpc inductive capacity of dissociated fetal lung tissue shows stage specificity with 24% of all MESC derivatives displaying Sftpc immunoreactivity after coculture with embryonic day 11.5 (E11.5) lung buds compared with 6% and 0.02% following coculture with E12.5 and E13.5 lung buds, respectively. MESC derivative Sftpc immunoreactivity follows a spatial and temporal specific maturation profile with an initially ubiquitous cellular Sftpc immunostaining pattern becoming apically polarized with time. Directing differentiation of MESCs into respiratory lineages has important implications for cell replacement therapeutics aimed at treating respiratory-specific diseases such as cystic fibrosis and idiopathic pulmonary fibrosis.
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Matveyenko, Aleksey V., Senta Georgia, Anil Bhushan, and Peter C. Butler. "Inconsistent formation and nonfunction of insulin-positive cells from pancreatic endoderm derived from human embryonic stem cells in athymic nude rats." American Journal of Physiology-Endocrinology and Metabolism 299, no. 5 (November 2010): E713—E720. http://dx.doi.org/10.1152/ajpendo.00279.2010.
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Embryonic stem cell therapy has been proposed as a therapeutic strategy to restore β-cell mass and function in T1DM. Recently, a group from Novocell (now ViaCyte) reported successful development of glucose-responsive islet-like structures after implantation of pancreatic endoderm (PE) derived from human embryonic stem cells (hESC) into immune-deficient mice. Our objective was to determine whether implantation of hESC-derived pancreatic endoderm from Novocell into athymic nude rats results in development of viable glucose-responsive pancreatic endocrine tissue. Athymic nude rats were implanted with PE derived from hESC either via implantation into the epididymal fat pads or by subcutaneous implantation into TheraCyte encapsulation devices for 20 wk. Blood glucose, weight, and human insulin/C-peptide secretion were monitored by weekly blood draws. Graft β-cell function was assessed by a glucose tolerance test, and graft morphology was assessed by immunohistochemistry and immunofluorescence. At 20 wk postimplantation, epididymal fat-implanted PE progressed to develop islet-like structures in 50% of implants, with a mean β-cell fractional area of 0.8 ± 0.3%. Human C-peptide and insulin were detectable, but at very low levels (C-peptide = 50 ± 26 pmol/l and insulin = 15 ± 7 pmol/l); however, there was no increase in human C-peptide/insulin levels after glucose challenge. There was no development of viable pancreatic tissue or meaningful secretory function when human PE was implanted in the TheraCyte encapsulation devices. These data confirm that islet-like structures develop from hESC differentiated to PE by the protocol developed by NovoCell. However, the extent of endocrine cell formation and secretory function is not yet sufficient to be clinically relevant.
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Dono, Rosanna. "Fibroblast growth factors as regulators of central nervous system development and function." American Journal of Physiology-Regulatory, Integrative and Comparative Physiology 284, no. 4 (April 1, 2003): R867—R881. http://dx.doi.org/10.1152/ajpregu.00533.2002.
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Fibroblast growth factors (FGFs) are multifunctional signaling proteins that regulate developmental processes and adult physiology. Over the last few years, important progress has been made in understanding the function of FGFs in the embryonic and adult central nervous system. In this review, I will first discuss studies showing that FGF signaling is already required during formation of the neural plate. Next, I will describe how FGF signaling centers control growth and patterning of specific brain structures. Finally, I will focus on the function of FGF signaling in the adult brain and in regulating maintenance and repair of damaged neural tissues.
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Zablon, Hesbon A., Chia-I. Ko, and Alvaro Puga. "Converging Roles of the Aryl Hydrocarbon Receptor in Early Embryonic Development, Maintenance of Stemness, and Tissue Repair." Toxicological Sciences 182, no. 1 (May 1, 2021): 1–9. http://dx.doi.org/10.1093/toxsci/kfab050.
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Abstract The aryl hydrocarbon receptor (AHR) is a ligand-activated transcription factor well-known for its adaptive role as a sensor of environmental toxicants and mediator of the metabolic detoxification of xenobiotic ligands. In addition, a growing body of experimental data has provided indisputable evidence that the AHR regulates critical functions of cell physiology and embryonic development. Recent studies have shown that the naïve AHR—that is, unliganded to xenobiotics but activated endogenously—has a crucial role in maintenance of embryonic stem cell pluripotency, tissue repair, and regulation of cancer stem cell stemness. Depending on the cellular context, AHR silences the expression of pluripotency genes Oct4 and Nanog and potentiates differentiation, whereas curtailing cellular plasticity and stemness. In these processes, AHR-mediated contextual responses and outcomes are dictated by changes of interacting partners in signaling pathways, gene networks, and cell-type-specific genomic structures. In this review, we focus on AHR-mediated changes of genomic architecture as an emerging mechanism for the AHR to regulate gene expression at the transcriptional level. Collective evidence places this receptor as a physiological hub connecting multiple biological processes whose disruption impacts on embryonic development, tissue repair, and maintenance or loss of stemness.
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Takei, Shunsuke, Hinako Ichikawa, Kohei Johkura, Akimi Mogi, Heesung No, Susumu Yoshie, Daihachiro Tomotsune, and Katsunori Sasaki. "Bone morphogenetic protein-4 promotes induction of cardiomyocytes from human embryonic stem cells in serum-based embryoid body development." American Journal of Physiology-Heart and Circulatory Physiology 296, no. 6 (June 2009): H1793—H1803. http://dx.doi.org/10.1152/ajpheart.01288.2008.
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Cardiomyocytes derived from human embryonic stem (ES) cells are a potential source for cell-based therapy for heart diseases. We studied the effect of bone morphogenetic protein (BMP)-4 in the presence of fetal bovine serum (FBS) on cardiac induction from human H1 ES cells during embryoid body (EB) development. Suspension culture for 4 days with 20% FBS produced the best results for the differentiation of early mesoderm and cardiomyocytes. The addition of Noggin reduced the incidence of beating EBs from 23.6% to 5.3%, which indicated the involvement of BMP signaling in the spontaneous cardiac differentiation. In this condition, treatment with 12.5–25 ng/ml BMP-4 during the 4-day suspension optimally promoted the cardiomyocyte differentiation. The incidence of beating EBs at 25 ng/ml BMP-4 reached 95.8% on day 6 of expansion and then plateaued until day 20. In real-time PCR analysis, the cardiac development-related genes MESP1 and Nkx2.5 were upregulated in the EB outgrowths by 25 ng/ml BMP-4. The activation of BMP signaling in EBs was confirmed by the increase in the phosphorylation of Smad1/5/8 and by the nuclear localization of phospho-Smad1/5/8 and Smad4. The addition of 150 ng/ml Noggin considerably decreased the incidence of beating EBs and Nkx2.5 expression, and Noggin alone increased Nestin expression and neural differentiation in EB outgrowths. The cardiomyocytes induced by 25 ng/ml BMP-4 showed proper cell biological characteristics and a course of differentiation as judged from isoproterenol administration, gene expression, protein assay, immunoreactivity, and subcellular structures. No remarkable change in the extent of apoptosis and proliferation in the cardiomyocytes was observed by BMP-4 treatment. These findings showed that BMP-4 in combination with FBS at the appropriate time and concentrations significantly promotes cardiomyocyte induction from human ES cells.
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Coutinho, Luiz L., Lakshmi K. Matukumalli, Tad S. Sonstegard, Curtis P. Van Tassell, Louis C. Gasbarre, Anthony V. Capuco, and Timothy P. L. Smith. "Discovery and profiling of bovine microRNAs from immune-related and embryonic tissues." Physiological Genomics 29, no. 1 (March 2007): 35–43. http://dx.doi.org/10.1152/physiolgenomics.00081.2006.
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MicroRNAs are small ∼22 nucleotide-long noncoding RNAs capable of controlling gene expression by inhibiting translation. Alignment of human microRNA stem-loop sequences (mir) against a recent draft sequence assembly of the bovine genome resulted in identification of 334 predicted bovine mir. We sequenced five tissue-specific cDNA libraries derived from the small RNA fractions of bovine embryo, thymus, small intestine, and lymph node to validate these predictions and identify new mir. This strategy combined with comparative sequence analysis identified 129 sequences that corresponded to mature microRNAs (miR). A total of 107 sequences aligned to known human mir, and 100 of these matched expressed miR. The other seven sequences represented novel miR expressed from the complementary strand of previously characterized human mir. The 22 sequences without matches displayed characteristic mir secondary structures when folded in silico, and 10 of these retained sequence conservation with other vertebrate species. Expression analysis based on sequence identity counts revealed that some miR were preferentially expressed in certain tissues, while bta-miR-26a and bta-miR-103 were prevalent in all tissues examined. These results support the premise that species differences in regulation of gene expression by miR occur primarily at the level of expression and processing.
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Ishikawa, Tadao, Shinsuke Nakayama, Tadashi Nakagawa, Kazuhide Horiguchi, Hiromi Misawa, Makoto Kadowaki, Akimasa Nakao, Soichiro Inoue, Terumasa Komuro, and Miyako Takaki. "Characterization of in vitro gutlike organ formed from mouse embryonic stem cells." American Journal of Physiology-Cell Physiology 286, no. 6 (June 2004): C1344—C1352. http://dx.doi.org/10.1152/ajpcell.00392.2003.
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Using an embryoid body (EB) culture system, we have made a functional organlike cluster: the “gut” from embryonic stem (ES) cells (ES gut). There are many types of ES clusters, because ES cells have a pluripotent ability to develop into a wide range of cell types. Before inducing specific differentiation by exogenously added factors, we characterized comprehensive physiological and morphological properties of ES guts. Each ES gut has a hemispherical (or cystic) structure and exhibits spontaneous contractions [mean frequency: 13.5 ± 8.8 cycles per min (cpm)]. A dense distribution of interstitial cells of Cajal (ICC) was identified by c-Kit immunoreactivity, and specific subcellular structures of ICC and smooth muscle cells were identified with electron microscopy. ICC frequently formed close contacts with the neighboring smooth muscle cells and occasionally formed gap junctions with other ICC. Widely propagating intracellular Ca2+ concentration oscillations were generated in the ES gut from the aggregates of c-Kit immunopositive cells. Plateau potentials, possibly pacemaker potentials in ICC, and electrical slow waves were recorded for the first time. These events were nifedipine insensitive, as in the mouse gut. Our present results indicate that the rhythmic pacemaker activity generated in ICC efficiently spreads to smooth muscle cells and drives spontaneous rhythmic contractions of the ES gut. The present characterization of physiological and morphological properties of ES gut paves the way for making appropriate models to investigate the origin of rhythmicity in the gut.
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Caiazza, Carmen, Silvia Parisi, and Massimiliano Caiazzo. "Liver Organoids: Updates on Disease Modeling and Biomedical Applications." Biology 10, no. 9 (August 27, 2021): 835. http://dx.doi.org/10.3390/biology10090835.
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Liver organoids are stem cell-derived 3D structures that are generated by liver differentiation signals in the presence of a supporting extracellular matrix. Liver organoids overcome low complexity grade of bidimensional culture and high costs of in vivo models thus representing a turning point for studying liver disease modeling. Liver organoids can be established from different sources as induced pluripotent stem cells (iPSCs), embryonic stem cells (ESCs), hepatoblasts and tissue-derived cells. This novel in vitro system represents an innovative tool to deeper understand the physiology and pathological mechanisms affecting the liver. In this review, we discuss the current advances in the field focusing on their application in modeling diseases, regenerative medicine and drug discovery.
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Baltanás, Fernando C., Rósula García-Navas, and Eugenio Santos. "SOS2 Comes to the Fore: Differential Functionalities in Physiology and Pathology." International Journal of Molecular Sciences 22, no. 12 (June 21, 2021): 6613. http://dx.doi.org/10.3390/ijms22126613.
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The SOS family of Ras-GEFs encompasses two highly homologous and widely expressed members, SOS1 and SOS2. Despite their similar structures and expression patterns, early studies of constitutive KO mice showing that SOS1-KO mutants were embryonic lethal while SOS2-KO mice were viable led to initially viewing SOS1 as the main Ras-GEF linking external stimuli to downstream RAS signaling, while obviating the functional significance of SOS2. Subsequently, different genetic and/or pharmacological ablation tools defined more precisely the functional specificity/redundancy of the SOS1/2 GEFs. Interestingly, the defective phenotypes observed in concomitantly ablated SOS1/2-DKO contexts are frequently much stronger than in single SOS1-KO scenarios and undetectable in single SOS2-KO cells, demonstrating functional redundancy between them and suggesting an ancillary role of SOS2 in the absence of SOS1. Preferential SOS1 role was also demonstrated in different RASopathies and tumors. Conversely, specific SOS2 functions, including a critical role in regulation of the RAS–PI3K/AKT signaling axis in keratinocytes and KRAS-driven tumor lines or in control of epidermal stem cell homeostasis, were also reported. Specific SOS2 mutations were also identified in some RASopathies and cancer forms. The relevance/specificity of the newly uncovered functional roles suggests that SOS2 should join SOS1 for consideration as a relevant biomarker/therapy target.
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Blutt, Sarah E., Ophir D. Klein, Mark Donowitz, Noah Shroyer, Chandan Guha, and Mary K. Estes. "Use of organoids to study regenerative responses to intestinal damage." American Journal of Physiology-Gastrointestinal and Liver Physiology 317, no. 6 (December 1, 2019): G845—G852. http://dx.doi.org/10.1152/ajpgi.00346.2018.
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Intestinal organoid cultures provide an in vitro model system for studying pathways and mechanisms involved in epithelial damage and repair. Derived from either embryonic or induced pluripotent stem cells or adult intestinal stem cells or tissues, these self-organizing, multicellular structures contain polarized mature cells that recapitulate both the physiology and heterogeneity of the intestinal epithelium. These cultures provide a cutting-edge technology for defining regenerative pathways that are induced following radiation or chemical damage, which directly target the cycling intestinal stem cell, or damage resulting from viral, bacterial, or parasitic infection of the epithelium. Novel signaling pathways or biological mechanisms identified from organoid studies that mediate regeneration of the epithelium following damage are likely to be important targets of preventive or therapeutic modalities to mitigate intestinal injury. The evolution of these cultures to include more components of the intestinal wall and the ability to genetically modify them are key components for defining the mechanisms that modulate epithelial regeneration.
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Johnson, J. Kelly, and V. A. Casagrande. "Prenatal development of axon outgrowth and connectivity in the ferret visual system." Visual Neuroscience 10, no. 1 (January 1993): 117–30. http://dx.doi.org/10.1017/s0952523800003266.
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AbstractThe objective of this study was to determine when the retina, lateral geniculate nucleus (LGN), and striate cortex first send out axons, and first connect with each other, during embryonic development in the ferret. Specifically, we were interested in the timing relationship between axon outgrowth and known temporal patterns of neurogenesis in the LGN and striate cortex. Ferrets (Mustela putorius furo) were selected for study because of their immature developmental state in late gestation and relatively large litters.We examined axon outgrowth from the retina, and anlagen of presumptive LGN and striate cortex between embryonic day 21–30 (E21–E30) using in situ inoculations of two fluorescent lipophilic dyes, Dil and DiA. Dil inoculations were made into the cortex and contralateral thalamus, and DiA inoculations were made into the contralateral eye. Retinal axon termination zones in the diencephalon following the DiA inoculations were used to validate the location of the LGN.Visual cortex and LGN neurogenesis begins at E20 in ferrets. No axon outgrowth could be documented from retina or anlagen of striate cortex and LGN until E24. At E24 some retinal axons reach and cross the chiasm, cortical axons extend some distance within the cortical radiations, and thalamic axons are within the internal capsule. Retinogeniculate, geniculocortical, and corticogeniculate axons extend to their target structures by E27, as evidenced by retrograde labeling in cells of origin.These data suggest that in the ferret retina, and developing LGN and striate cortex, (1) axon outgrowth from each visual area begins within 24-h of each other, after neurogenesis has begun at the source but before it is complete in the target; (2) axons may be generated before parent cell bodies have completed migration; and (3) arriving axons are in a position to influence target structures almost from their inception.
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Yue, Xinping, and Robert J. Tomanek. "Effects of VEGF165 and VEGF121 on vasculogenesis and angiogenesis in cultured embryonic quail hearts." American Journal of Physiology-Heart and Circulatory Physiology 280, no. 5 (May 1, 2001): H2240—H2247. http://dx.doi.org/10.1152/ajpheart.2001.280.5.h2240.
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It has been documented that hypoxia enhances coronary vasculogenesis and angiogenesis in cultured embryonic quail hearts via the upregulation of vascular endothelial growth factor (VEGF). In this study, we compared the functions of two VEGF splice variants. Ventricles from 6-day-old embryonic quail hearts were cultured on three-dimensional collagen gels. Recombinant human VEGF121or VEGF165 were added to the culture medium for 48 h, and vascular growth was visualized by immunostaining with a quail-specific endothelial cell (EC) marker, QH1. VEGF165 enhanced vascular growth in a dose-dependent manner: 5 ng/ml of VEGF165 slightly increased the number of ECs, 10 ng/ml of VEGF165 increased the incorporation of ECs into tubular structures, and at 20 ng/ml of VEGF165 wider tubes were formed. This pattern plateaued at the 50 ng/ml dose. In contrast, VEGF121 did not enhance either the number of ECs or tube formation at these or higher dosages. Combined effects of hypoxia and exogenous VEGF165 were then compared. Tube formation from the heart explants treated with both hypoxia and 50 ng/ml of VEGF165 had a morphology intermediate to those treated with hypoxia or VEGF165 alone. Immunocytochemistry study revealed EC lumenization under all culture conditions. However, the addition of VEGF165 stimulated the coalescence of ECs to form larger vessels. We conclude the following: 1) VEGF121 and VEGF165 induced by hypoxia have different functions on coronary vascular growth, 2) unknown factors induced by hypoxia can modify the effect of VEGF165, and 3) EC lumenization observed in the heart explant culture closely mimics in vivo coronary vasculogenesis.
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Igarashi, P., G. B. Vanden Heuvel, J. A. Payne, and B. Forbush. "Cloning, embryonic expression, and alternative splicing of a murine kidney-specific Na-K-Cl cotransporter." American Journal of Physiology-Renal Physiology 269, no. 3 (September 1, 1995): F405—F418. http://dx.doi.org/10.1152/ajprenal.1995.269.3.f405.
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A full-length cDNA encoding the murine renal Na-K-Cl cotransporter (NKCC2) was cloned using library screening and anchored polymerase chain reaction. The deduced protein sequence contained 1,095 amino acids and was 93.5% identical to rabbit NKCC2 and 97.6% identical to rat BSC1. Two potential sites of phosphorylation by adenosine 3',5'-cyclic monophosphate-dependent protein kinase and seven potential sites of phosphorylation by protein kinase C, which were previously identified in the rabbit and rat sequences, were phylogenetically conserved in the mouse. The expression of NKCC2 in the mouse was examined with Northern blot analysis and in situ hybridization. Expression of NKCC2 was kidney specific in both adult and embryonic mice. In the developing metanephros, NKCC2 was induced at 14.5 days post coitus and was expressed in distal limbs of immature loops of Henle but was absent from the ureteric bud, S-shaped bodies, and earlier nephrogenic structures. Similar to the rabbit, isoforms of NKCC2 that differed in the sequence of a 96-bp segment were identified in the mouse. In situ hybridization revealed that the isoforms exhibited different patterns of expression in the mature thick ascending limb of the loop of Henle as follows: isoform F was most highly expressed in the inner stripe of outer medulla, isoform A was most highly expressed in the outer stripe of the outer medulla, and isoform B was most highly expressed in the cortical thick ascending limb. To verify that the isoforms were generated by alternative splicing of mutually exclusive cassette exons, genomic clones encoding murine NKCC2 were characterized. Cassette exons were identified that corresponded to each of the three isoforms and were flanked by consensus splice donor and acceptor sequences.
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Rymer, Christopher, Jose Paredes, Kimmo Halt, Caitlin Schaefer, John Wiersch, Guangfeng Zhang, Douglas Potoka, et al. "Renal blood flow and oxygenation drive nephron progenitor differentiation." American Journal of Physiology-Renal Physiology 307, no. 3 (August 1, 2014): F337—F345. http://dx.doi.org/10.1152/ajprenal.00208.2014.
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During kidney development, the vasculature develops via both angiogenesis (branching from major vessels) and vasculogenesis (de novo vessel formation). The formation and perfusion of renal blood vessels are vastly understudied. In the present study, we investigated the regulatory role of renal blood flow and O2 concentration on nephron progenitor differentiation during ontogeny. To elucidate the presence of blood flow, ultrasound-guided intracardiac microinjection was performed, and FITC-tagged tomato lectin was perfused through the embryo. Kidneys were costained for the vasculature, ureteric epithelium, nephron progenitors, and nephron structures. We also analyzed nephron differentiation in normoxia compared with hypoxia. At embryonic day 13.5 (E13.5), the major vascular branches were perfused; however, smaller-caliber peripheral vessels remained unperfused. By E15.5, peripheral vessels started to be perfused as well as glomeruli. While the interior kidney vessels were perfused, the peripheral vessels (nephrogenic zone) remained unperfused. Directly adjacent and internal to the nephrogenic zone, we found differentiated nephron structures surrounded and infiltrated by perfused vessels. Furthermore, we determined that at low O2 concentration, little nephron progenitor differentiation was observed; at higher O2 concentrations, more differentiation of the nephron progenitors was induced. The formation of the developing renal vessels occurs before the onset of blood flow. Furthermore, renal blood flow and oxygenation are critical for nephron progenitor differentiation.
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Ruan, Jiuxiao, Huhui Chen, Tao Zhu, Yaoguang Yu, Yawen Lei, Liangbing Yuan, Jun Liu, et al. "Brassinosteroids repress the seed maturation program during the seed-to-seedling transition." Plant Physiology 186, no. 1 (February 23, 2021): 534–48. http://dx.doi.org/10.1093/plphys/kiab089.
Full textAbstract:
Abstract In flowering plants, repression of the seed maturation program is essential for the transition from the seed to the vegetative phase, but the underlying mechanisms remain poorly understood. The B3-domain protein VIVIPAROUS1/ABSCISIC ACID-INSENSITIVE3-LIKE 1 (VAL1) is involved in repressing the seed maturation program. Here we uncovered a molecular network triggered by the plant hormone brassinosteroid (BR) that inhibits the seed maturation program during the seed-to-seedling transition in Arabidopsis (Arabidopsis thaliana). val1-2 mutant seedlings treated with a BR biosynthesis inhibitor form embryonic structures, whereas BR signaling gain-of-function mutations rescue the embryonic structure trait. Furthermore, the BR-activated transcription factors BRI1-EMS-SUPPRESSOR 1 and BRASSINAZOLE-RESISTANT 1 bind directly to the promoter of AGAMOUS-LIKE15 (AGL15), which encodes a transcription factor involved in activating the seed maturation program, and suppress its expression. Genetic analysis indicated that BR signaling is epistatic to AGL15 and represses the seed maturation program by downregulating AGL15. Finally, we showed that the BR-mediated pathway functions synergistically with the VAL1/2-mediated pathway to ensure the full repression of the seed maturation program. Together, our work uncovered a mechanism underlying the suppression of the seed maturation program, shedding light on how BR promotes seedling growth.
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Dodd, J., and T. M. Jessell. "Cell surface glycoconjugates and carbohydrate-binding proteins: possible recognition signals in sensory neurone development." Journal of Experimental Biology 124, no. 1 (September 1, 1986): 225–38. http://dx.doi.org/10.1242/jeb.124.1.225.
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Dorsal root ganglion (DRG) neurones transmit cutaneous sensory information from the periphery to the dorsal horn of the spinal cord. Subpopulations of DRG neurones that subserve distinct sensory modalities project to discrete regions in the dorsal horn. The formation of specific sensory connections during development may involve cell-surface interactions with spinal cord cells. Molecules that are expressed on the surface of functional subpopulations of DRG and dorsal horn neurones have therefore been identified. Distinct subsets of DRG neurones express globo- or lactoseries carbohydrate differentiation antigens. The expression of defined carbohydrate structures correlates with the embryonic lineage, peptide phenotype and the central termination site of DRG neurones. Similar or identical glycoconjugates have been implicated in cellular interactions that contribute to preimplantation embryonic development. Small-diameter DRG neurones that project to the superficial dorsal horn express N-acetyllactosamine backbone structures that are potential ligands for beta-galactoside-specific binding proteins (lectins). Two lectins have been identified that are expressed early in development in the superficial dorsal horn. These complementary molecules may contribute to the development of sensory afferent projections in the spinal cord.
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Kwon, Yong-Jun, Weontae Lee, Auguste Genovesio, and Neil Emans. "A High-Content Subtractive Screen for Selecting Small Molecules Affecting Internalization of GPCRs." Journal of Biomolecular Screening 17, no. 3 (November 15, 2011): 379–85. http://dx.doi.org/10.1177/1087057111427347.
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G-protein–coupled receptors (GPCRs) are pivotal in cellular responses to the environment and are common drug targets. Identification of selective small molecules acting on single GPCRs is complicated by the shared machinery coupling signal transduction to physiology. Here, we demonstrate a high-content screen using a panel of GPCR assays to identify receptor selective molecules acting within the kinase/phosphatase inhibitor family. A collection of 88 kinase and phosphatase inhibitors was screened against seven agonist-induced GPCR internalization cell models as well as transferrin uptake in human embryonic kidney cells. Molecules acting on a single receptor were identified through excluding pan-specific compounds affecting housekeeping endocytosis or disrupting internalization of multiple receptors. We identified compounds acting on a sole GPCR from activities in a broad range of chemical structures that could not be easily sorted by conventional means. Selective analysis can therefore rapidly select compounds selectively affecting GPCR activity with specificity to one receptor class through high-content screening.
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Mondrinos, M. J., S. Koutzaki, P. I. Lelkes, and C. M. Finck. "A tissue-engineered model of fetal distal lung tissue." American Journal of Physiology-Lung Cellular and Molecular Physiology 293, no. 3 (September 2007): L639—L650. http://dx.doi.org/10.1152/ajplung.00403.2006.
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In extending our previous studies toward development of an engineered distal lung tissue construct (M. J. Mondrinos, S. Koutzaki, E. Jiwanmall, M. Li, J. P. Dechadarevian, P. I. Lelkes, and C. M. Finck. Tissue Eng 12: 717–728, 2006), we studied the effects of exogenous fibroblast growth factors FGF10, FGF7, and FGF2 on mixed populations of embryonic day 17.5 murine fetal pulmonary cells cultured in three-dimensional collagen gels. The morphogenic effects of the FGFs alone and in various combinations were assessed by whole mount immunohistochemistry and confocal microscopy. FGF10/7 significantly increased epithelial budding and proliferation; however, only FGF10 alone induced widespread budding. FGF7 alone induced dilation of epithelial structures but not widespread budding. FGF2 alone had a similar dilation, but not budding, effect in epithelial structures, and, in addition, significantly enhanced endothelial tubular morphogenesis and network formation, as well as mesenchymal proliferation. The combination of FGF10/7/2 induced robust budding of epithelial structures and the formation of uniform endothelial networks in parallel. These data suggest that appropriate combinations of exogenous FGFs chosen to target specific FGF receptor isoforms will allow for control of lung epithelial and mesenchymal cell behavior in the context of an engineered system. We propose that tissue-engineered fetal distal lung constructs could provide a potential source of tissue or cells for lung augmentation in pediatric pulmonary pathologies, such as pulmonary hypoplasia and bronchopulmonary dysplasia. In addition, engineered systems will provide alternative in vitro venues for the study of lung developmental biology and pathobiology.
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Yamamoto, Kimiko, Takaaki Sokabe, Tetsuro Watabe, Kohei Miyazono, Jun K. Yamashita, Syotaro Obi, Norihiko Ohura, Akiko Matsushita, Akira Kamiya, and Joji Ando. "Fluid shear stress induces differentiation of Flk-1-positive embryonic stem cells into vascular endothelial cells in vitro." American Journal of Physiology-Heart and Circulatory Physiology 288, no. 4 (April 2005): H1915—H1924. http://dx.doi.org/10.1152/ajpheart.00956.2004.
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Pluripotent embryonic stem (ES) cells are capable of differentiating into all cell lineages, but the molecular mechanisms that regulate ES cell differentiation have not been sufficiently explored. In this study, we report that shear stress, a mechanical force generated by fluid flow, can induce ES cell differentiation. When Flk-1-positive (Flk-1+) mouse ES cells were subjected to shear stress, their cell density increased markedly, and a larger percentage of the cells were in the S and G2-M phases of the cell cycle than Flk-1+ES cells cultured under static conditions. Shear stress significantly increased the expression of the vascular endothelial cell-specific markers Flk-1, Flt-1, vascular endothelial cadherin, and PECAM-1 at both the protein level and the mRNA level, but it had no effect on expression of the mural cell marker smooth muscle α-actin, blood cell marker CD3, or the epithelial cell marker keratin. These findings indicate that shear stress selectively promotes the differentiation of Flk-1+ES cells into the endothelial cell lineage. The shear stressed Flk-1+ES cells formed tubelike structures in collagen gel and developed an extensive tubular network significantly faster than the static controls. Shear stress induced tyrosine phosphorylation of Flk-1 in Flk-1+ES cells that was blocked by a Flk-1 kinase inhibitor, SU1498, but not by a neutralizing antibody against VEGF. SU1498 also abolished the shear stress-induced proliferation and differentiation of Flk-1+ES cells, indicating that a ligand-independent activation of Flk-1 plays an important role in the shear stress-mediated proliferation and differentiation by Flk-1+ES cells.
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Yosypiv, Ihor V., Maria Luisa S. Sequeira-Lopez, Renfang Song, and Alexandre De Goes Martini. "Stromal prorenin receptor is critical for normal kidney development." American Journal of Physiology-Regulatory, Integrative and Comparative Physiology 316, no. 5 (May 1, 2019): R640—R650. http://dx.doi.org/10.1152/ajpregu.00320.2018.
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Formation of the metanephric kidney requires coordinated interaction among the stroma, ureteric bud, and cap mesenchyme. The transcription factor Foxd1, a specific marker of renal stromal cells, is critical for normal kidney development. The prorenin receptor (PRR), a receptor for renin and prorenin, is also an accessory subunit of the vacuolar proton pump V-ATPase. Global loss of PRR is embryonically lethal in mice, indicating an essential role of the PRR in embryonic development. Here, we report that conditional deletion of the PRR in Foxd1+ stromal progenitors in mice ( cKO) results in neonatal mortality. The kidneys of surviving mice show reduced expression of stromal markers Foxd1 and Meis1 and a marked decrease in arterial and arteriolar development with the subsequent decreased number of glomeruli, expansion of Six2+ nephron progenitors, and delay in nephron differentiation. Intrarenal arteries and arterioles in cKO mice were fewer and thinner and showed a marked decrease in the expression of renin, suggesting a central role for the PRR in the development of renin-expressing cells, which in turn are essential for the proper formation of the renal arterial tree. We conclude that stromal PRR is crucial for the appropriate differentiation of the renal arterial tree, which in turn may restrict excessive expansion of nephron progenitors to promote a coordinated and proper morphogenesis of the nephrovascular structures of the mammalian kidney.
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Teerijoki, Heli, Aleksei Krasnov, Yuri Gorodilov, Sanjeev Krishna, and Hannu Mölsä. "Rainbow trout glucose transporter (OnmyGLUT1): functional assessment in Xenopus laevis oocytes and expression in fish embryos." Journal of Experimental Biology 204, no. 15 (August 1, 2001): 2667–73. http://dx.doi.org/10.1242/jeb.204.15.2667.
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SUMMARY Recently, we reported the cloning of a putative glucose transporter (OnmyGLUT1) from rainbow trout embryos. In this paper, we describe the functional characteristics of OnmyGLUT1 and its expression during embryonic development of rainbow trout. Transport of d-glucose was analysed in Xenopus laevis oocytes following microinjection of mRNA transcribed in vitro. These experiments confirmed that OnmyGLUT1 is a facilitative Na+-independent transporter. Assessment of substrate selectivity, sensitivity to cytochalasin B and phloretin and kinetic parameters showed that the rainbow trout glucose transporter was similar to a carp transporter and to mammalian GLUT1. Embryonic expression of OnmyGLUT1 was studied using whole-mount in situ hybridization. Ubiquitous distribution of transcripts was observed until the early phase of somitogenesis. During the course of organogenesis, somitic expression decreased along the rostro-caudal axis, finally ceasing in the mature somites. The OnmyGLUT1 transcripts were detected in the neural crest during the whole study period. Transcripts were also found in structures that are likely to originate from the neural crest cells (gill arches, pectoral fins, upper jaw, olfactory organs and primordia of mouth lips). Hexose transport activity was detected at all developmental stages after blastulation. Cytochalasin B blocked the accumulation of phosphorylated 2-deoxy-d-glucose by dissociated embryonic cells, suggesting an important role for transport in glucose metabolism.
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Li, Xing, Almudena Martinez-Fernandez, Katherine A. Hartjes, Jean-Pierre A. Kocher, Timothy M. Olson, Andre Terzic, and Timothy J. Nelson. "Transcriptional atlas of cardiogenesis maps congenital heart disease interactome." Physiological Genomics 46, no. 13 (July 1, 2014): 482–95. http://dx.doi.org/10.1152/physiolgenomics.00015.2014.
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Mammalian heart development is built on highly conserved molecular mechanisms with polygenetic perturbations resulting in a spectrum of congenital heart diseases (CHD). However, knowledge of cardiogenic ontogeny that regulates proper cardiogenesis remains largely based on candidate-gene approaches. Mapping the dynamic transcriptional landscape of cardiogenesis from a genomic perspective is essential to integrate the knowledge of heart development into translational applications that accelerate disease discovery efforts toward mechanistic-based treatment strategies. Herein, we designed a time-course transcriptome analysis to investigate the genome-wide dynamic expression landscape of innate murine cardiogenesis ranging from embryonic stem cells to adult cardiac structures. This comprehensive analysis generated temporal and spatial expression profiles, revealed stage-specific gene functions, and mapped the dynamic transcriptome of cardiogenesis to curated pathways. Reconciling known genetic underpinnings of CHD, we deconstructed a disease-centric dynamic interactome encoded within this cardiogenic atlas to identify stage-specific developmental disturbances clustered on regulation of epithelial-to-mesenchymal transition (EMT), BMP signaling, NF-AT signaling, TGFb-dependent EMT, and Notch signaling. Collectively, this cardiogenic transcriptional landscape defines the time-dependent expression of cardiac ontogeny and prioritizes regulatory networks at the interface between health and disease.
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Aboitiz, Francisco, Daniver Morales, and Juan Montiel. "An interdisciplinary approach to brain evolution: A long due debate." Behavioral and Brain Sciences 26, no. 5 (October 2003): 572–76. http://dx.doi.org/10.1017/s0140525x03420128.
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A dorsalization mechanism is a good candidate for the evolutionary origin of the isocortex, producing a radial and tangential expansion of the dorsal pallium (and perhaps other structures that acquired a cortical phenotype). Evidence suggests that a large part of the dorsal ventricular ridge (DVR) of reptiles and birds derives from the embryonic ventral pallium, whereas the isocortex possibly derives mostly from the dorsal pallium. In early mammals, the development of olfactory-hippocampal associative networks may have been pivotal in facilitating the selection of a larger and more complex dorsal pallium which received both collothalamic and lemnothalamic sensory information. Finally, although it is not clear exactly when mammalian brain expansion began, fossil evidence indicates that this was a late event in mammaliaform evolution.
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Rasmussen, Tina H., Thomas K. Andreassen, Søren N. Pedersen, Leo T. M. Van der Ven, Poul Bjerregaard, and Bodil Korsgaard. "Effects of waterborne exposure of octylphenol and oestrogen on pregnant viviparous eelpout (Zoarces viviparus) and her embryos in ovario." Journal of Experimental Biology 205, no. 24 (December 15, 2002): 3857–76. http://dx.doi.org/10.1242/jeb.205.24.3857.
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SUMMARY Exposure to oestrogenic chemicals (xeno-oestrogens) may have severe effects on embryonic development. The present study investigates whether the oestrogenic endocrine disruptor 4-tert-octylphenol (4-tOP) or 17β-oestradiol (E2) is accumulated in the viviparous fish the eelpout (Zoarces viviparus) and transferred to the embryos in ovario and subsequently affects embryonic development, including gonadal differentiation. Pregnant eelpouts were exposed to nominal concentrations of 25 μgl-1 or 100 μgl-1 4-tOP (OP25 or OP100,respectively) or 0.5 μgl-1 E2 in water. During 4-tOP exposure, the compound accumulated in both plasma and ovarian fluid in a concentration-dependent manner. In the mother fish, the oestrogenic biomarkers, vitellogenin (Vtg) in plasma, Vtg mRNA in liver and oestrogen-binding activity in liver, were all induced by 4-tOP (and by E2) at an actual concentration of 14 μgl-1. E2 and 4-tOP were examined for their potency to disturb the maternal—foetal trophic relationship by disturbing the physiology of the ovary and by changing the distribution of essential nutrients normally transported to embryos during pregnancy. After exposure to E2 or 4-tOP, calcium was depleted from the ovarian fluid and the level of free amino acids available in maternal plasma was decreased. A marked overall effect on ovarian components, including the ovarian sac, ovarian fluid and embryonic mass, was evident. Embryonic growth was significantly decreased, which might in part be attributed to disturbances of the maternal—foetal trophic relationship. Marked inductions of Vtg mRNA and Vtg protein, determined by RT-PCR and immunohistochemistry, respectively, were found in embryos from the OP100 group — the only group to show considerable accumulation of an oestrogenic compound in the ovarian fluid. A different pattern of gonadal development was found in embryos from the OP100 group compared with embryos from the control, OP25 or E2 groups, in which approximately 50% had normal ovaries and 50% had normal presmptive male gonads. In the OP100 group,46% had normal ovaries but, in contrast to controls, only 22% had normal presumptive male gonads, whereas the remaining 32% had abnormal male gonads with structures resembling the endo-ovarian cavity of a female gonad. As oestrogen receptor (ER) expression was detected by in situhybridisation in early differentiating gonads, these effects could be mediated by direct interaction of the xeno-oestrogens with gonadal ER. In conclusion,this study indicates that the xeno-oestrogen 4-tOP can be transferred from the water via the mother fish to the ovarian fluid and can subsequently disturb the maternal—foetal trophic relationship and cause severe effects on embryonic development, including gonadal differentiation in ovario.
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Leri, Annarosa, Jan Kajstura, and Piero Anversa. "Cardiac Stem Cells and Mechanisms of Myocardial Regeneration." Physiological Reviews 85, no. 4 (October 2005): 1373–416. http://dx.doi.org/10.1152/physrev.00013.2005.
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This review discusses current understanding of the role that endogenous and exogenous progenitor cells may have in the treatment of the diseased heart. In the last several years, a major effort has been made in an attempt to identify immature cells capable of differentiating into cell lineages different from the organ of origin to be employed for the regeneration of the damaged heart. Embryonic stem cells (ESCs) and bone marrow-derived cells (BMCs) have been extensively studied and characterized, and dramatic advances have been made in the clinical application of BMCs in heart failure of ischemic and nonischemic origin. However, a controversy exists concerning the ability of BMCs to acquire cardiac cell lineages and reconstitute the myocardium lost after infarction. The recognition that the adult heart possesses a stem cell compartment that can regenerate myocytes and coronary vessels has raised the unique possibility to rebuild dead myocardium after infarction, to repopulate the hypertrophic decompensated heart with new better functioning myocytes and vascular structures, and, perhaps, to reverse ventricular dilation and wall thinning. Cardiac stem cells may become the most important cell for cardiac repair.
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Kandilogiannakis, L., E. Filidou, I. Drygiannakis, G. Tarapatzi, K. Arvanitidis, G. Bamias, V. Valatas, V. Paspaliaris, and G. Kolios. "P049 Development of human embryonic stem cell-derived intestinal organoids for in vitro studies on intestinal inflammation and fibrosis." Journal of Crohn's and Colitis 15, Supplement_1 (May 1, 2021): S158. http://dx.doi.org/10.1093/ecco-jcc/jjab076.178.
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Abstract Background Organoids are self-renewing, 3D structures, consisting of different cell types, with histology and physiology features very close to the physiology of the studied organ. Specifically, human Intestinal Organoids (HIOs) develop epithelial crypts consisting of all subtypes of intestinal epithelial cells which are surrounded by mesenchymal cells. Our aim was to develop 3D HIOs from human embryonic stem cells (hESCs) and examine the expression of fibrotic and mesenchymal factors during their maturation process. Additionally, we investigated the effect of the pro-inflammatory cytokines, IL-1α and TNF-α on the expression of fibrotic and inflammatory mediators in HIOs. Methods The human ESC line (H1) was cultured and then differentiated towards HIOs using commercially available kit. HIOs were characterized by immunofluorescence in all differentiation stages. In order to examine their maturation process, we compared the mRNA expression of fibrotic and mesenchymal markers from passages 1–10. In order to examine their functionality, HIOs from different passages were stimulated with 5ng/ml IL-1α and 50ng/ml TNF-α for 12 hours, total RNA was collected and the fibrotic and inflammatory mRNA expression was examined. The mRNA transcripts of CD90, collagen type I, III, fibronectin, CXCL8, CXCL10 and CXCL11 were measured by reverse transcription quantitative PCR. Results HIOs were successfully developed as they were stained positive for all tested markers throughout their developmental process. Regarding their maturation process, we observed high expression of CD90, collagen type I, type III and fibronectin that was gradually decreased during passages. As for the fibrotic and inflammatory responses from HIOs, we found that the IL-1α and TNF-α stimulation resulted in statistically significant upregulation of the fibrotic factors, fibronectin, collagen type I and type III in culture passages 2 and 4, but had no effect in culture passages 8 and 10. Similarly, IL-1α and TNF-α stimulation led to the statistically significant induction of the inflammatory chemokines CXCL8, CXCL10 and CXCL11 in culture passages 2 and 4, while no effect was observed in culture passages 8 and 10. Conclusion Our findings indicate that HIOs contain a functional mesenchymal component that is gradually diminished during passages. Inflammatory and fibrotic responses of HIOs seem to depend on the fitness of their mesenchyme. IBD studies using HIOs as in vitro models should be performed on early passages, when HIO’s mesenchymal component is still functional.
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Pohl, Martin, Hiroyuki Sakurai, Kevin T. Bush, and Sanjay K. Nigam. "Matrix metalloproteinases and their inhibitors regulate in vitro ureteric bud branching morphogenesis." American Journal of Physiology-Renal Physiology 279, no. 5 (November 1, 2000): F891—F900. http://dx.doi.org/10.1152/ajprenal.2000.279.5.f891.
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Mammalian kidney development is initiated by the mutual interaction between embryonic metanephric mesenchyme (MM) and the ureteric bud (UB), leading to tightly controlled UB branching morphogenesis. In a three-dimensional cell culture model, which employs MM cell-derived conditioned medium (BSN-CM) to induce UB cell branching morphogenesis in extracellular matrix (ECM) gels (Sakurai H, Barros EJ, Tsukamoto T, Barasch J, and Nigam SK. Proc Natl Acad Sci USA 94: 6279–6284, 1997), branching morphogenesis was inhibited by both chemical agents (ilomastat and 1,10-orthophenanthroline) and a physiological protein factor [tissue inhibitor of metalloproteinases (TIMP)-2], known to act as matrix metalloproteinase (MMP) inhibitors. In addition, UB branching was inhibited in isolated UB culture (Qiao J, Sakurai H, and Nigam SK. Proc Natl Acad Sci USA96: 7330–7335, 1999) by TIMP-2 and ilomastat, suggesting a direct role for MMPs in UB branching. Gelatin zymography and enzymatic measurement of MMP activity revealed that MMPs could originate from at least three different sources: the conditioned medium, the ECM, and the UB cells themselves. In the UB cells, transcription of several MMPs [gelatinase A (MMP2) and B (MMP9), stromelysin (MMP3), MT1-MMP] and TIMPs was altered by BSN-CM and changed as more complex branching structures formed. The ECM appeared to serve as both a reservoir for MMPs and modulated their expression because different ECM compositions altered the total MMP activity as well as specific subsets of MMPs expressed by the UB cells (as determined by zymography and Northern analysis). In the context of UB branching morphogenesis during kidney development, our data suggest a complex model in which soluble factors produced by the MM, in the context of specific ECM components, modulate the expression of specific subsets of MMPs and TIMPs in the UB, which alter as structures develop and the matrix environment changes. This suggests distinct roles for different subsets of MMPs and their inhibitors during different phases of branching morphogenesis.
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Shen, Yuan, L. Leatherbury, J. Rosenthal, Qing Yu, M. A. Pappas, A. Wessels, J. Lucas, et al. "Cardiovascular phenotyping of fetal mice by noninvasive high-frequency ultrasound facilitates recovery of ENU-induced mutations causing congenital cardiac and extracardiac defects." Physiological Genomics 24, no. 1 (January 2006): 23–36. http://dx.doi.org/10.1152/physiolgenomics.00129.2005.
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As part of a large-scale noninvasive fetal ultrasound screen to recover ethylnitrosourea (ENU)-induced mutations causing congenital heart defects in mice, we established a high-throughput ultrasound scanning strategy for interrogating fetal mice in utero utilizing three orthogonal imaging planes defined by the fetus’ vertebral column and body axes, structures readily seen by ultrasound. This contrasts with the difficulty of acquiring clinical ultrasound imaging planes which are defined by the fetal heart. By use of the three orthogonal imaging planes for two-dimensional (2D) imaging together with color flow, spectral Doppler, and M-mode imaging, all of the major elements of the heart can be evaluated. In this manner, 10,091 ENU-mutagenized mouse fetuses were ultrasound scanned between embryonic days 12.5 and 19.5, with 324 fetuses found to die prenatally and 425 exhibiting cardiovascular defects. Further analysis by necropsy and histology showed heart defects that included conotruncal anomalies, obstructive lesions, and shunt lesions as well as other complex heart diseases. Ultrasound imaging also identified craniofacial/head defects and body wall closure defects, which necropsy revealed as encephalocele, holoprosencephaly, omphalocele, or gastroschisis. Genome scanning mapped one ENU-induced mutation associated with persistence truncus arteriosus and holoprosencephaly to mouse chromosome 2, while another mutation associated with cardiac defects and omphalocele was mapped to mouse chromosome 17. These studies show the efficacy of this novel ultrasound scanning strategy for noninvasive ultrasound phenotyping to facilitate the recovery of ENU-induced mutations causing congenital heart defects and other extracardiac anomalies.
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Li, Ling, Rachel Black, Zhendong Ma, Qiwen Yang, Andrew Wang, and Fangming Lin. "Use of mouse hematopoietic stem and progenitor cells to treat acute kidney injury." American Journal of Physiology-Renal Physiology 302, no. 1 (January 1, 2012): F9—F19. http://dx.doi.org/10.1152/ajprenal.00377.2011.
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New and effective treatment for acute kidney injury remains a challenge. Here, we induced mouse hematopoietic stem and progenitor cells (HSPC) to differentiate into cells that partially resemble a renal cell phenotype and tested their therapeutic potential. We sequentially treated HSPC with a combination of protein factors for 1 wk to generate a large number of cells that expressed renal developmentally regulated genes and protein. Cell fate conversion was associated with increased histone acetylation on promoters of renal-related genes. Further treatment of the cells with a histone deacetylase inhibitor improved the efficiency of cell conversion by sixfold. Treated cells formed tubular structures in three-dimensional cultures and were integrated into tubules of embryonic kidney organ cultures. When injected under the renal capsule, they integrated into renal tubules of postischemic kidneys and expressed the epithelial marker E-cadherin. No teratoma formation was detected 2 and 6 mo after cell injection, supporting the safety of using these cells. Furthermore, intravenous injection of the cells into mice with renal ischemic injury improved kidney function and morphology by increasing endogenous renal repair and decreasing tubular cell death. The cells produced biologically effective concentrations of renotrophic factors including VEGF, IGF-1, and HGF to stimulate epithelial proliferation and tubular repair. Our study indicates that hematopoietic stem and progenitor cells can be converted to a large number of renal-like cells within a short period for potential treatment of acute kidney injury.
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Kroiss, Matthias, Marina Leyerer, Valentin Gorboulev, Thomas Kühlkamp, Helmut Kipp, and Hermann Koepsell. "Transporter regulator RS1 (RSC1A1) coats thetrans-Golgi network and migrates into the nucleus." American Journal of Physiology-Renal Physiology 291, no. 6 (December 2006): F1201—F1212. http://dx.doi.org/10.1152/ajprenal.00067.2006.
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The product of gene RSC1A1, named RS1, is involved in transcriptional and posttranscriptional regulation of sodium-d-glucose cotransporter SGLT1, and removal of RS1 in mice led to an increase of SGLT1 expression in small intestine and to obesity (Osswald C, Baumgarten K, Stümpel F, Gorboulev V, Akimjanova M, Knobeloch K-P, Horak I, Kluge R, Joost H-G, and Koepsell H. Mol Cell Biol 25: 78–87, 2005). Previous data showed that RS1 inhibits transcription of SGLT1 in LLC-PK1cells derived from porcine kidney. A decrease of the intracellular amount of RS1 protein was observed during cell confluence, which was paralleled by transcriptional upregulation of SGLT1. In the present study, the subcellular distributions of endogenously expressed RS1 and SGLT1 were compared in LLC-PK1cells and human embryonic kidney (HEK)-293 cells using immunofluorescence microscopy. RS1 was located at the plasma membrane, at the entire trans-Golgi network (TGN), and within the nucleus. Treatment of LLC-PK1cells with brefeldin A induced rapid release of RS1 from the TGN, and confluence of LLC-PK1cells was accompanied by reduction of nuclear location of RS1; 84–90% of subconfluent cells and 5–34% of confluent cells contained RS1 in the nuclei. This suggests that confluence-dependent transcriptional inhibition by RS1 is partially regulated by nuclear migration. Furthermore, we assigned SGLT1 to microtubule-associated tubulovesicular structures and dynamin-containing parts of the TGN. The data indicate that RS1 inhibits the dynamin-dependent release of SGLT1-containing vesicles from the TGN.
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Koiwai, Kotaro, Kazue Inaba, Kana Morohashi, Sora Enya, Reina Arai, Hirotatsu Kojima, Takayoshi Okabe, et al. "An integrated approach to unravel a crucial structural property required for the function of the insect steroidogenic Halloween protein Noppera-bo." Journal of Biological Chemistry 295, no. 20 (April 2, 2020): 7154–67. http://dx.doi.org/10.1074/jbc.ra119.011463.
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Ecdysteroids are the principal steroid hormones essential for insect development and physiology. In the last 18 years, several enzymes responsible for ecdysteroid biosynthesis encoded by Halloween genes were identified and genetically and biochemically characterized. However, the tertiary structures of these proteins have not yet been characterized. Here, we report the results of an integrated series of in silico, in vitro, and in vivo analyses of the Halloween GST protein Noppera-bo (Nobo). We determined crystal structures of Drosophila melanogaster Nobo (DmNobo) complexed with GSH and 17β-estradiol, a DmNobo inhibitor. 17β-Estradiol almost fully occupied the putative ligand-binding pocket and a prominent hydrogen bond formed between 17β-estradiol and Asp-113 of DmNobo. We found that Asp-113 is essential for 17β-estradiol–mediated inhibition of DmNobo enzymatic activity, as 17β-estradiol did not inhibit and physically interacted less with the D113A DmNobo variant. Asp-113 is highly conserved among Nobo proteins, but not among other GSTs, implying that this residue is important for endogenous Nobo function. Indeed, a homozygous nobo allele with the D113A substitution exhibited embryonic lethality and an undifferentiated cuticle structure, a phenocopy of complete loss-of-function nobo homozygotes. These results suggest that the nobo family of GST proteins has acquired a unique amino acid residue that appears to be essential for binding an endogenous sterol substrate to regulate ecdysteroid biosynthesis. To the best of our knowledge, ours is the first study describing the structural characteristics of insect steroidogenic Halloween proteins. Our findings provide insights relevant for applied entomology to develop insecticides that specifically inhibit ecdysteroid biosynthesis.
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Sakurai, H., and S. K. Nigam. "Transforming growth factor-beta selectively inhibits branching morphogenesis but not tubulogenesis." American Journal of Physiology-Renal Physiology 272, no. 1 (January 1, 1997): F139—F146. http://dx.doi.org/10.1152/ajprenal.1997.272.1.f139.
Full textAbstract:
When cultured in type I collagen gels, two kidney-derived cell lines, Madin-Darby canine kidney (MDCK) cells and murine inner medullary collecting duct (mIMCD3) cells, from branching tubular structures in the presence of Swiss 3T3 conditioned medium, in which hepatocyte growth factor (HGF) is the major branching tubule inducing factor. However, upon incubation with transforming growth factor-beta (TGF-beta) in the presence of 3T3 conditioned medium, MDCK tubulogenesis and branching was markedly inhibited. In contrast, mIMCD3 cells, which are much less susceptible to growth and tubulogenesis inhibition by TGF-beta, formed long straight tubulelike structures in presence of TGF-beta, suggesting a dissociation between tubulogenesis and branching morphogenesis. Interestingly, those long tubules that did branch often superficially resembled the early branching ureteric bud in embryonic kidneys. Quantitation of branching events revealed a selective branch-inhibiting effect of TGF-beta on mIMCD3 cells at concentrations between 0.02 and 2 ng/ml. There was no qualitative or quantitative difference among TGF-beta 1, -beta 2, and -beta 3 on inhibition of branching events, suggesting existence of potentially redundant mechanisms for modulating branching morphogenesis. Concentrations of TGF-beta that resulted in long nonbranching tubules also altered the profile of extracellular matrix-degrading proteases and their inhibitors expressed by developing tubules. Ratios of urokinase type plasminogen activator (u-PA) to plasminogen activator inhibitor (PAI-l) and matrix metalloprotease (MMP)-1 to tissue inhibitor of metalloprotease (TIMP)-1 were both markedly decreased. In addition, apart from a direct effect on epithelial cell branching morphogenesis, TGF-beta downregulated the expression of HGF mRNA in Swiss 3T3 cells. Thus TGF-beta exerts at least three distinct effects relevant to tubulogenesis and branching morphogenesis inhibition of branching morphogenesis alone (mIMCD3 cells), inhibition of both tubulogenesis and branching morphogenesis (MDCK cells), and inhibition of the expression of growth factor which induce tubulogenesis and branching morphogenesis (3T3 cells). In the context of epithelial tissue development, which requires tightly regulated branching tubulogenesis of epithelial cells, the data suggest a model where branching patterns are regulated by a precise temporal and spatial balance between branching morphogens such as HGF and inhibitory morphogens such as members of the TGF-beta superfamily [e.g., TGF-beta isoforms, certain bone morphogenetic proteins].
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Gurkiewicz, Meron, Alon Korngreen, Stephen G. Waxman, and Angelika Lampert. "Kinetic modeling of Nav1.7 provides insight into erythromelalgia-associated F1449V mutation." Journal of Neurophysiology 105, no. 4 (April 2011): 1546–57. http://dx.doi.org/10.1152/jn.00703.2010.
Full textAbstract:
Gain-of-function mutations of the voltage-gated sodium channel (VGSC) Nav1.7 have been linked to human pain disorders. The mutation F1449V, located at the intracellular end of transmembrane helix S6 of domain III, induces the inherited pain syndrome erythromelalgia. A kinetic model of wild-type (WT) and F1449V Nav1.7 may provide a basis for predicting putative intraprotein interactions. We semiautomatically constrained a Markov model using stochastic search algorithms and whole cell patch-clamp recordings from human embryonic kidney cells transfected with Nav1.7 and its F1449V mutation. The best models obtained simulated known differences in action potential thresholds and firing patterns in spinal sensory neurons expressing WT and F1449V. The most suitable Markov model consisted of three closed, one open, and two inactivated states. The model predicted that the F1449V mutation shifts occupancy of the closed states closer to the open state, making it easier for the channel pore to open. It also predicted that F1449V's second inactivated state is more than four times more likely to be occupied than the equivalent state in WT at hyperpolarized potentials, although the mutation still lowered the firing threshold of action potentials. The differences between WT and F1449V were not limited to a single transition. Thus a point mutation in position F1449, while phenotypically most probably affecting the activation gate, may also modify channel functions mediated by structures in more distant areas of the channel protein.
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Liu, Huajun, Joshua Atkins, and Robert S. Kass. "Common Molecular Determinants of Flecainide and Lidocaine Block of Heart Na+ Channels." Journal of General Physiology 121, no. 3 (February 10, 2003): 199–214. http://dx.doi.org/10.1085/jgp.20028723.
Full textAbstract:
Flecainide (pKa 9.3, 99% charged at pH 7.4) and lidocaine (pKa 7.6–8.0, ∼50% neutral at pH 7.4) have similar structures but markedly different effects on Na+ channel activity. Both drugs cause well-characterized use-dependent block (UDB) of Na+ channels due to stabilization of the inactivated state, but flecainide requires that channels first open before block develops, whereas lidocaine is believed to bind directly to the inactivated state. To test whether the charge on flecainide might determine its state specificity of Na+ channel blockade, we developed two flecainide analogues, NU-FL (pKa 6.4), that is 90% neutral at pH 7.4, and a quaternary flecainide analogue, QX-FL, that is fully charged at physiological pH. We examined the effects of flecainide, NU-FL, QX-FL, and lidocaine on human cardiac Na+ channels expressed in human embryonic kidney (HEK) 293 cells. At physiological pH, NU-FL, like lidocaine but not flecainide, interacts preferentially with inactivated channels without prerequisite channel opening, and causes minimal UDB. We find that UDB develops predominantly by the charged form of flecainide as evidenced by investigation of QX-FL at physiological pH and NU-FL investigated over a more acidic pH range where its charged fraction is increased. QX-FL is a potent blocker of channels when applied from inside the cell, but acts very weakly with external application. UDB by QX-FL, like flecainide, develops only after channels open. Once blocked, channels recover very slowly from QX-FL block, apparently without requisite channel opening. Our data strongly suggest that it is the difference in degree of ionization (pKa) between lidocaine and flecainide, rather than gross structural features, that determines distinction in block of cardiac Na+ channels. The data also suggest that the two drugs share a common receptor but, consistent with the modulated receptor hypothesis, reach this receptor by distinct routes dictated by the degree of ionization of the drug molecules.
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Wang, Zhuren, Nathan C. Wong, Yvonne Cheng, Steven J. Kehl, and David Fedida. "Control of voltage-gated K+ channel permeability to NMDG+ by a residue at the outer pore." Journal of General Physiology 133, no. 4 (March 30, 2009): 361–74. http://dx.doi.org/10.1085/jgp.200810139.
Full textAbstract:
Crystal structures of potassium (K+) channels reveal that the selectivity filter, the narrow portion of the pore, is only ∼3-Å wide and buttressed from behind, so that its ability to expand is highly constrained, and the permeation of molecules larger than Rb+ (2.96 Å in diameter) is prevented. N-methyl-d-glucamine (NMDG+), an organic monovalent cation, is thought to be a blocker of Kv channels, as it is much larger (∼7.3 Å in mean diameter) than K+ (2.66 Å in diameter). However, in the absence of K+, significant NMDG+ currents could be recorded from human embryonic kidney cells expressing Kv3.1 or Kv3.2b channels and Kv1.5 R487Y/V, but not wild-type channels. Inward currents were much larger than outward currents due to the presence of intracellular Mg2+ (1 mM), which blocked the outward NMDG+ current, resulting in a strong inward rectification. The NMDG+ current was inhibited by extracellular 4-aminopyridine (5 mM) or tetraethylammonium (10 mM), and largely eliminated in Kv3.2b by an S6 mutation that prevents the channel from opening (P468W) and by a pore helix mutation in Kv1.5 R487Y (W472F) that inactivates the channel at rest. These data indicate that NMDG+ passes through the open ion-conducting pore and suggest a very flexible nature of the selectivity filter itself. 0.3 or 1 mM K+ added to the external NMDG+ solution positively shifted the reversal potential by ∼16 or 31 mV, respectively, giving a permeability ratio for K+ over NMDG+ (PK+/PNMDG+) of ∼240. Reversal potential shifts in mixtures of K+ and NMDG+ are in accordance with PK+/PNMDG+, indicating that the ions compete for permeation and suggesting that NMDG+ passes through the open state. Comparison of the outer pore regions of Kv3 and Kv1.5 channels identified an Arg residue in Kv1.5 that is replaced by a Tyr in Kv3 channels. Substituting R with Y or V allowed Kv1.5 channels to conduct NMDG+, suggesting a regulation by this outer pore residue of Kv channel flexibility and, as a result, permeability.
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Stoykov, I., B. Zandieh-Doulabi, A. F. M. Moorman, V. Christoffels, W. M. Wiersinga, and O. Bakker. "Expression pattern and ontogenesis of thyroid hormone receptor isoforms in the mouse heart." Journal of Endocrinology 189, no. 2 (May 2006): 231–45. http://dx.doi.org/10.1677/joe.1.06282.
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Nuclear thyroid hormone (T3) receptors (TR) play a critical role in mediating the effects of T3 on development, differentiation and normal physiology of many organs. The heart is a major target organ of T3, and recent studies in knockout mice demonstrated distinct effects of the different TR isoforms on cardiac function, but the specific actions of TR isoforms and their specific localization in the heart remain unclear. We therefore studied the expression of TRα1, TRα2 and TRβ1 isoforms in the mouse heart at different stages of development, using monoclonal antibodies against TRα1, TRα2 and TRβ1. In order to identify distinct components of the embryonic heart, in situ hybridization for cardiac-specific markers was used with the expression pattern of sarcoplasmic reticulum calcium-ATPase 2a as a marker of myocardial structures, while the pattern of expression of connexin40 was used to indicate the developing chamber myocardium and peripheral ventricular conduction system. Here we show that in the ventricles of the adult heart the TRβ1 isoform is confined to the cells that form the peripheral ventricular conduction system. TRα1, on the other hand, is present in working myocardium as well as in the peripheral ventricular conduction system. In the atria and in the proximal conduction system (sinoatrial node, atrio-ventricular node), TRα1 and TRβ1 isoforms are co-expressed. We also found the heterogeneous expression of the TRα1, TRα2 and TRβ1 isoforms in the developing mouse heart, which, in the case of the TRβ1 isoform, gradually revealed a dynamic expression pattern. It was present in all cardiomyocytes at the early stages of cardiogenesis, but from embryonic day 11.5 and into adulthood, TRβ1 demonstrated a gradual confinement to the peripheral ventricular conduction system (PVCS), suggesting a specific role of this isoform in the formation of PVCS. Detailed knowledge of the distribution of TRα1 and TRβ1 in the heart is of importance for understanding not only their mechanism of action in the heart but also the design and (clinical) use of TR isoform-specific agonists and antagonists.
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Quinn, Peter M. J., and Jan Wijnholds. "Retinogenesis of the Human Fetal Retina: An Apical Polarity Perspective." Genes 10, no. 12 (November 29, 2019): 987. http://dx.doi.org/10.3390/genes10120987.
Full textAbstract:
The Crumbs complex has prominent roles in the control of apical cell polarity, in the coupling of cell density sensing to downstream cell signaling pathways, and in regulating junctional structures and cell adhesion. The Crumbs complex acts as a conductor orchestrating multiple downstream signaling pathways in epithelial and neuronal tissue development. These pathways lead to the regulation of cell size, cell fate, cell self-renewal, proliferation, differentiation, migration, mitosis, and apoptosis. In retinogenesis, these are all pivotal processes with important roles for the Crumbs complex to maintain proper spatiotemporal cell processes. Loss of Crumbs function in the retina results in loss of the stratified appearance resulting in retinal degeneration and loss of visual function. In this review, we begin by discussing the physiology of vision. We continue by outlining the processes of retinogenesis and how well this is recapitulated between the human fetal retina and human embryonic stem cell (ESC) or induced pluripotent stem cell (iPSC)-derived retinal organoids. Additionally, we discuss the functionality of in utero and preterm human fetal retina and the current level of functionality as detected in human stem cell-derived organoids. We discuss the roles of apical-basal cell polarity in retinogenesis with a focus on Leber congenital amaurosis which leads to blindness shortly after birth. Finally, we discuss Crumbs homolog (CRB)-based gene augmentation.
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Blaschke, Rüdiger J., Nathan D. Hahurij, Sanne Kuijper, Steffen Just, Lambertus J. Wisse, Kirsten Deissler, Tina Maxelon, et al. "Targeted Mutation Reveals Essential Functions of the Homeodomain Transcription Factor Shox2 in Sinoatrial and Pacemaking Development." Circulation 115, no. 14 (April 10, 2007): 1830–38. http://dx.doi.org/10.1161/circulationaha.106.637819.
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Background— Identifying molecular pathways regulating the development of pacemaking and coordinated heartbeat is crucial for a comprehensive mechanistic understanding of arrhythmia-related diseases. Elucidation of these pathways has been complicated mainly by an insufficient definition of the developmental structures involved in these processes and the unavailability of animal models specifically targeting the relevant tissues. Here, we report on a highly restricted expression pattern of the homeodomain transcription factor Shox2 in the sinus venosus myocardium, including the sinoatrial nodal region and the venous valves. Methods and Results— To investigate its function in vivo, we have generated mouse lines carrying a targeted mutation of the Shox2 gene. Although heterozygous animals did not exhibit obvious defects, homozygosity of the targeted allele led to embryonic lethality at 11.5 to 13.5 dpc. Shox2 −/− embryos exhibited severe hypoplasia of the sinus venosus myocardium in the posterior heart field, including the sinoatrial nodal region and venous valves. We furthermore demonstrate aberrant expression of connexin 40 and connexin 43 and the transcription factor Nkx2.5 in vivo specifically within the sinoatrial nodal region and show that Shox2 deficiency interferes with pacemaking function in zebrafish embryos. Conclusions— From these results, we postulate a critical function of Shox2 in the recruitment of sinus venosus myocardium comprising the sinoatrial nodal region.
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Tu, M. C., H. B. Lillywhite, J. G. Menon, and G. K. Menon. "Postnatal ecdysis establishes the permeability barrier in snake skin: new insights into barrier lipid structures." Journal of Experimental Biology 205, no. 19 (October 1, 2002): 3019–30. http://dx.doi.org/10.1242/jeb.205.19.3019.
Full textAbstract:
SUMMARY A competent barrier to transepidermal water loss (TEWL) is essential for terrestrial life. In various vertebrates, epidermal water barriers composed of lipids prevent excessive TEWL, which varies inversely with habitat aridity. Little is known, however, about the mechanisms and regulation of permeability relative to natal transition from the `aqueous' environments of gestation to the `aerial' environments of terrestrial neonates. We investigated newly hatched California king snakes Lampropeltis getula to test the hypothesis that the first ecdysis is important for establishing the barrier to TEWL. We found that skin resistance to TEWL increases twofold following the first postnatal ecdysis, corresponding with a roughly twofold increase in thickness and deposition of lamellar lipids in the mesos layer, the site of the skin permeability barrier in snakes. In addition, novel observations on lipid inclusions within the alpha layer of epidermis suggest that this layer has functional similarities with avian epidermis. It appears that emergence of the integument from embryonic fluids, and its subsequent pan-body replacement following contact with air, are essential for completion of barrier competence in the newborn. These conditions provide a potentially useful model for investigations on the mechanism of barrier formation. We also found that hatchling snakes are transiently endothermic, with skin temperatures elevated by approximately 0.6°C above ambient air temperature during the period of barrier formation. Behaviourally, hatchlings showed a higher tendency to seek humid microenvironments before the first ecdysis than after. The degree of water movement across the integument might explain the switch from reclusive to dispersive behaviours associated with postnatal ecdysis in snakes.
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Seal, Hayley E., Sigmund J. Lilian, Anastas Popratiloff, June C. Hirsch, and Kenna D. Peusner. "Implementing the chick embryo model to study vestibular developmental disorders." Journal of Neurophysiology 122, no. 6 (December 1, 2019): 2272–83. http://dx.doi.org/10.1152/jn.00434.2019.
Full textAbstract:
Children with congenital vestibular disorders show delayed motor development and challenges in maintaining posture and balance. Computed tomography images reveal that these children have abnormal inner ears in the form of a sac, with the semicircular canals missing or truncated. Little is known about how this inner ear abnormality affects central vestibular development. At present, mice with the chromodomain helicase DNA-binding protein 7 mutation are the most common model for studying congenital vestibular disorders, despite forming multiple diverse inner ear phenotypes and inducing abnormal cerebellar and visual system development. To identify the effects of a sac-like inner ear on central vestibular development, we have designed and implemented a new model, the anterior-posterior axis rotated otocyst (ARO) chick, which forms a sac-like inner ear in 85% of cases. The ARO chick is produced by anterior-posterior rotation of the otocyst at embryonic day 2. Here, we describe for the first time the 15% of ARO chicks that form three small semicircular canals and rename the ARO chicks forming sacs (ARO/s chicks). The basic features of the vestibular sensory organs in ARO/s chicks are similar to those found in patients’ sacs, and ARO/s hatchlings experience balance and walking problems like patients. Thus, ARO/s chicks have a reproducible inner ear phenotype without abnormalities in vestibular-related structures, making the model a relatively simple one to evaluate the relationship between the sac-like inner ear pathology and formation of the central vestibular neural circuitry. Here, we describe unpublished details on the surgical approaches to produce ARO chicks, including pitfalls and difficulties to avoid. NEW & NOTEWORTHY This paper describes simple techniques for chick otocyst rotation resulting in a sac-like inner ear (85%), the common phenotype in congenital vestibular disorders. We now describe anterior-posterior axis rotated otocyst chicks, which form three small canals (15%), and rename chicks forming a sac (ARO/s chicks). Basic protocols and potential complications of otocyst rotation are described. With the use of ARO/s chicks, it will be possible to determine how the vestibular neural circuit is modified by sac-like inner ear formation.