Academic literature on the topic 'Targeted transcription regulation'
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Journal articles on the topic "Targeted transcription regulation"
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Braun, Christian J., Peter M. Bruno, Max A. Horlbeck, Luke A. Gilbert, Jonathan S. Weissman, and Michael T. Hemann. "Versatile in vivo regulation of tumor phenotypes by dCas9-mediated transcriptional perturbation." Proceedings of the National Academy of Sciences 113, no. 27 (June 20, 2016): E3892—E3900. http://dx.doi.org/10.1073/pnas.1600582113.
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Targeted transcriptional regulation is a powerful tool to study genetic mediators of cellular behavior. Here, we show that catalytically dead Cas9 (dCas9) targeted to genomic regions upstream or downstream of the transcription start site allows for specific and sustainable gene-expression level alterations in tumor cells in vitro and in syngeneic immune-competent mouse models. We used this approach for a high-coverage pooled gene-activation screen in vivo and discovered previously unidentified modulators of tumor growth and therapeutic response. Moreover, by using dCas9 linked to an activation domain, we can either enhance or suppress target gene expression simply by changing the genetic location of dCas9 binding relative to the transcription start site. We demonstrate that these directed changes in gene-transcription levels occur with minimal off-target effects. Our findings highlight the use of dCas9-mediated transcriptional regulation as a versatile tool to reproducibly interrogate tumor phenotypes in vivo.
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Li, Conghui, Honghong Wang, Zhinang Yin, Pingping Fang, Ruijing Xiao, Ying Xiang, Wen Wang, et al. "Ligand-induced native G-quadruplex stabilization impairs transcription initiation." Genome Research 31, no. 9 (August 16, 2021): 1546–60. http://dx.doi.org/10.1101/gr.275431.121.
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G-quadruplexes (G4s) are noncanonical DNA secondary structures formed through the self-association of guanines, and G4s are distributed widely across the genome. G4 participates in multiple biological processes including gene transcription, and G4-targeted ligands serve as potential therapeutic agents for DNA-targeted therapies. However, genome-wide studies of the exact roles of G4s in transcriptional regulation are still lacking. Here, we establish a sensitive G4-CUT&Tag method for genome-wide profiling of native G4s with high resolution and specificity. We find that native G4 signals are cell type–specific and are associated with transcriptional regulatory elements carrying active epigenetic modifications. Drug-induced promoter-proximal RNA polymerase II pausing promotes nearby G4 formation. In contrast, G4 stabilization by G4-targeted ligands globally reduces RNA polymerase II occupancy at gene promoters as well as nascent RNA synthesis. Moreover, ligand-induced G4 stabilization modulates chromatin states and impedes transcription initiation via inhibition of general transcription factors loading to promoters. Together, our study reveals a reciprocal genome-wide regulation between native G4 dynamics and gene transcription, which will deepen our understanding of G4 biology toward therapeutically targeting G4s in human diseases.
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Ahmed, Mahmoud, Trang Huyen Lai, Trang Minh Pham, Sahib Zada, Omar Elashkar, Jin Seok Hwang, and Deok Ryong Kim. "Hierarchical regulation of autophagy during adipocyte differentiation." PLOS ONE 17, no. 1 (January 26, 2022): e0250865. http://dx.doi.org/10.1371/journal.pone.0250865.
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We previously showed that some adipogenic transcription factors such as CEBPB and PPARG directly and indirectly regulate autophagy gene expression in adipogenesis. The order and effect of these events are undetermined. In this study, we modeled the gene expression, DNA-binding of transcriptional regulators, and histone modifications during adipocyte differentiation and evaluated the effect of the regulators on gene expression in terms of direction and magnitude. Then, we identified the overlap of the transcription factors and co-factors binding sites and targets. Finally, we built a chromatin state model based on the histone marks and studied their relation to the factors’ binding. Adipogenic factors differentially regulated autophagy genes as part of the differentiation program. Co-regulators associated with specific transcription factors and preceded them to the regulatory regions. Transcription factors differed in the binding time and location, and their effect on expression was either localized or long-lasting. Adipogenic factors disproportionately targeted genes coding for autophagy-specific transcription factors. In sum, a hierarchical arrangement between adipogenic transcription factors and co-factors drives the regulation of autophagy during adipocyte differentiation.
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Scott, James N. F., Adam P. Kupinski, and Joan Boyes. "Targeted genome regulation and modification using transcription activator-like effectors." FEBS Journal 281, no. 20 (September 6, 2014): 4583–97. http://dx.doi.org/10.1111/febs.12973.
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Huh, Hyunbin, Dong Kim, Han-Sol Jeong, and Hyun Park. "Regulation of TEAD Transcription Factors in Cancer Biology." Cells 8, no. 6 (June 17, 2019): 600. http://dx.doi.org/10.3390/cells8060600.
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Transcriptional enhanced associate domain (TEAD) transcription factors play important roles during development, cell proliferation, regeneration, and tissue homeostasis. TEAD integrates with and coordinates various signal transduction pathways including Hippo, Wnt, transforming growth factor beta (TGFβ), and epidermal growth factor receptor (EGFR) pathways. TEAD deregulation affects well-established cancer genes such as KRAS, BRAF, LKB1, NF2, and MYC, and its transcriptional output plays an important role in tumor progression, metastasis, cancer metabolism, immunity, and drug resistance. To date, TEADs have been recognized to be key transcription factors of the Hippo pathway. Therefore, most studies are focused on the Hippo kinases and YAP/TAZ, whereas the Hippo-dependent and Hippo-independent regulators and regulations governing TEAD only emerged recently. Deregulation of the TEAD transcriptional output plays important roles in tumor progression and serves as a prognostic biomarker due to high correlation with clinicopathological parameters in human malignancies. In addition, discovering the molecular mechanisms of TEAD, such as post-translational modifications and nucleocytoplasmic shuttling, represents an important means of modulating TEAD transcriptional activity. Collectively, this review highlights the role of TEAD in multistep-tumorigenesis by interacting with upstream oncogenic signaling pathways and controlling downstream target genes, which provides unprecedented insight and rationale into developing TEAD-targeted anticancer therapeutics.
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Uprety, Bhawana, Amala Kaja, Jannatul Ferdoush, Rwik Sen, and Sukesh R. Bhaumik. "Regulation of Antisense Transcription by NuA4 Histone Acetyltransferase and Other Chromatin Regulatory Factors." Molecular and Cellular Biology 36, no. 6 (January 11, 2016): 992–1006. http://dx.doi.org/10.1128/mcb.00808-15.
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NuA4 histone lysine (K) acetyltransferase (KAT) promotes transcriptional initiation of TATA-binding protein (TBP)-associated factor (TAF)-dependent ribosomal protein genes. TAFs have also been recently found to enhance antisense transcription from the 3′ end of theGAL10coding sequence. However, it remains unknown whether, like sense transcription of the ribosomal protein genes, TAF-dependent antisense transcription ofGAL10also requires NuA4 KAT. Here, we show that NuA4 KAT associates with theGAL10antisense transcription initiation site at the 3′ end of the coding sequence. Such association of NuA4 KAT depends on the Reb1p-binding site that recruits Reb1p activator to theGAL10antisense transcription initiation site. Targeted recruitment of NuA4 KAT to theGAL10antisense transcription initiation site promotesGAL10antisense transcription. Like NuA4 KAT, histone H3 K4/36 methyltransferases and histone H2B ubiquitin conjugase facilitateGAL10antisense transcription, while the Swi/Snf and SAGA chromatin remodeling/modification factors are dispensable for antisense, but not sense, transcription ofGAL10. Taken together, our results demonstrate for the first time the roles of NuA4 KAT and other chromatin regulatory factors in controlling antisense transcription, thus illuminating chromatin regulation of antisense transcription.
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Perez-Oquendo, Mabel, and Don L. Gibbons. "Regulation of ZEB1 Function and Molecular Associations in Tumor Progression and Metastasis." Cancers 14, no. 8 (April 7, 2022): 1864. http://dx.doi.org/10.3390/cancers14081864.
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Zinc finger E-box binding homeobox 1 (ZEB1) is a pleiotropic transcription factor frequently expressed in carcinomas. ZEB1 orchestrates the transcription of genes in the control of several key developmental processes and tumor metastasis via the epithelial-to-mesenchymal transition (EMT). The biological function of ZEB1 is regulated through pathways that influence its transcription and post-transcriptional mechanisms. Diverse signaling pathways converge to induce ZEB1 activity; however, only a few studies have focused on the molecular associations or functional changes of ZEB1 by post-translational modifications (PTMs). Due to the robust effect of ZEB1 as a transcription repressor of epithelial genes during EMT, the contribution of PTMs in the regulation of ZEB1-targeted gene expression is an active area of investigation. Herein, we review the pivotal roles that phosphorylation, acetylation, ubiquitination, sumoylation, and other modifications have in regulating the molecular associations and behavior of ZEB1. We also outline several questions regarding the PTM-mediated regulation of ZEB1 that remain unanswered. The areas of research covered in this review are contributing to new treatment strategies for cancer by improving our mechanistic understanding of ZEB1-mediated EMT.
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Imoberdorf, Rachel Maria, Irini Topalidou, and Michel Strubin. "A Role for Gcn5-Mediated Global Histone Acetylation in Transcriptional Regulation." Molecular and Cellular Biology 26, no. 5 (March 1, 2006): 1610–16. http://dx.doi.org/10.1128/mcb.26.5.1610-1616.2006.
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ABSTRACT Transcriptional activators often require histone acetyltransferases (HATs) for full activity. The common explanation is that activators directly recruit HATs to gene promoters to locally hyperacetylate histones and thereby facilitate transcription complex formation. However, in addition to being targeted to specific loci, HATs such as Gcn5 also modify histones genome-wide. Here we provide evidence for a role of this global HAT activity in regulated transcription. We show that activation by direct recruitment of the transcriptional machinery neither recruits Gcn5 nor induces changes in histone acetylation yet can strongly depend on Gcn5 at promoters showing a high basal state of Gcn5-mediated histone acetylation. We also show that Gcn5 dependency varies among core promoters and is influenced by the strength of interaction used to recruit the machinery and by the affinity of the latter for the core promoter. These data support a role for global Gcn5 HAT activity in modulating transcription independently of its known coactivator function.
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Nourani, Amine, Yannick Doyon, Rhea T. Utley, Stéphane Allard, William S. Lane, and Jacques Côté. "Role of an ING1 Growth Regulator in Transcriptional Activation and Targeted Histone Acetylation by the NuA4 Complex." Molecular and Cellular Biology 21, no. 22 (November 15, 2001): 7629–40. http://dx.doi.org/10.1128/mcb.21.22.7629-7640.2001.
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ABSTRACT The yeast NuA4 complex is a histone H4 and H2A acetyltransferase involved in transcription regulation and essential for cell cycle progression. We identify here a novel subunit of the complex, Yng2p, a plant homeodomain (PHD)-finger protein homologous to human p33/ING1, which has tumor suppressor activity and is essential for p53 function. Mass spectrometry, immunoblotting, and immunoprecipitation experiments confirm the stable stoichiometric association of this protein with purified NuA4. Yeast cells harboring a deletion of theYNG2 gene show severe growth phenotype and have gene-specific transcription defects. NuA4 complex purified from the mutant strain is low in abundance and shows weak histone acetyltransferase activity. We demonstrate conservation of function by the requirement of Yng2p for p53 to function as a transcriptional activator in yeast. Accordingly, p53 interacts with NuA4 in vitro and in vivo, an interaction reminiscent of the p53-ING1 physical link in human cells. The growth defect of Δyng2 cells can be rescued by the N-terminal part of the protein, lacking the PHD-finger. While Yng2 PHD-finger is not required for p53 interaction, it is necessary for full expression of the p53-responsive gene and other NuA4 target genes. Transcriptional activation by p53 in vivo is associated with targeted NuA4-dependent histone H4 hyperacetylation, while histone H3 acetylation levels remain unchanged. These results emphasize the essential role of the NuA4 complex in the control of cell proliferation through gene-specific transcription regulation. They also suggest that regulation of mammalian cell proliferation by p53-dependent transcriptional activation functions through recruitment of an ING1-containing histone acetyltransferase complex.
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Zhang, Yixin, Yanlan Mo, Liyuan Han, Zhenyuan Sun, and Wenzhong Xu. "Exploring Transcriptional Regulation of Hyperaccumulation in Sedum plumbizincicola through Integrated Transcriptome Analysis and CRISPR/Cas9 Technology." International Journal of Molecular Sciences 24, no. 14 (July 24, 2023): 11845. http://dx.doi.org/10.3390/ijms241411845.
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The cadmium hyperaccumulator Sedum plumbizincicola has remarkable abilities for cadmium (Cd) transport, accumulation and detoxification, but the transcriptional regulation mechanisms responsible for its Cd hyperaccumulation remain unknown. To address this knowledge gap, we conducted a comparative transcriptome study between S. plumbizincicola and the non-hyperaccumulating ecotype (NHE) of Sedum alfredii with or without Cd treatment. Our results revealed many differentially expressed genes involved in heavy metal transport and detoxification that were abundantly expressed in S. plumbizincicola. Additionally, we identified a large number of differentially expressed transcription factor genes, highlighting the complexity of transcriptional regulatory networks. We further screened four transcription factor genes that were highly expressed in the roots of S. plumbizincicola as candidate genes for creating CRISPR/Cas9 knockout mutations. Among these, the SpARR11 and SpMYB84 mutant lines exhibited decreased Cd accumulation in their aboveground parts, suggesting that these two transcription factors may play a role in the regulation of the Cd hyperaccumulation in S. plumbizincicola. Although further research will be required to determine the precise targeted genes of these transcription factors, combined transcriptome analysis and CRISPR/Cas9 technology provides unprecedented opportunities for identifying transcription factors related to Cd hyperaccumulation and contributes to the understanding of the transcriptional regulation mechanism of hyperaccumulation in S. plumbizincicola.
Dissertations / Theses on the topic "Targeted transcription regulation"
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Maeder, Morgan Lee. "Engineered DNA-Binding Proteins for Targeted Genome Editing and Gene Regulation." Thesis, Harvard University, 2013. http://dissertations.umi.com/gsas.harvard:10770.
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Engineered DNA-binding proteins enable targeted manipulation of the genome. Zinc fingers are the most well characterized DNA-binding domain and for many years research has focused on understanding and manipulating the sequence-specificities of these proteins. Recently, major advances in the ability to engineer zinc finger proteins, as well as the discovery of a new class of DNA-binding domains - transcription activator-like effectors (TALEs), have made it possible to rapidly and reliably engineer proteins targeted to any sequence of interest. With this capability, focus has shifted to exploring the applications of this powerful technology. In this dissertation I explore three important applications of engineered DNA-binding proteins.
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Yi, Jia. "The Role of Convergent Transcription in Regulating Alternative Splicing : Targeted Epigenetic Modification via Repurposed CRISPR/Cas9 System and Its Impact on Alternative Splicing Modulation." Electronic Thesis or Diss., Sorbonne université, 2020. http://www.theses.fr/2020SORUS382.
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L'épissage alternatif de l'ARN précurseur est un processus co-transcriptionnel qui affecte la grande majorité des gènes humains et contribue à la diversité des protéines. Le dérèglement d'un tel processus est impliqué dans diverses maladies, y compris la tumorigènes. Cependant, les mécanismes qui régulent ces processus restaient à caractériser. Dans cette étude, nous avons montré que les perturbations de l'épissage alternatif étaient corrélées aux dérèglements de la transcription convergente et de la méthylation de l'ADN. Une transcription convergente peut être générée entre des paires de gènes voisins en en orientation opposée, ou entre des amplificateurs intragéniques et leur gène hôte. CENPO et ADCY3 ont été identifiés comme une paire de gènes de transcription convergentes. Nous avons constaté, dans un modèle de progression tumorale du cancer du sein, que le changement d'épissage de l'exon22 variant d'ADCY3 était corrélé à une augmentation de sa transcription qui allait contre celle de CENPO. En utilisant le système de répression ciblée de la transcription CRISPRi, nous avons démontré que l’inhibition de la transcription de CENPO ne pouvait pas inverser l'altération d'épissage alternatif d'ADCY3 dans les cellules cancéreuses (DCIS). Un activateur intragénique actif a été identifié dans l'intron16 du gène CD44, en aval de ses exons alternatifs. En utilisant le système d'activation ciblée de transcription CRISPRa, nous avons montré que l’augmentation de la transcription de CD44 ne pouvait pas modifier l'épissage alternatif de CD44 dans les cellules DCIS. Ces résultats suggèrent que la modification de transcription convergente par des changements d’activité des promoteurs ne permet pas d’altérer l'épissage alternatif de ADCY3 et CD44 dans les cellules DCIS. Cependant, en remplaçant l'amplificateur intragénique par un promoteur inductible, nous avons constaté que l'activation de la transcription intragénique augmentait le niveau d'inclusion de plusieurs exons alternatifs de CD44 dans les cellules HCT116. Ce résultat suggère que la transcription convergente local pourrait avoir un impact direct sur l'épissage alternatif de CD44. De plus, en utilisant le système de méthylation de l'ADN ciblée CRISPR/dCas9-DNMT3b, nous avons démontré que la méthylation de l'ADN au niveau des exons variants pouvait modifier l'épissage alternatif de CD44. Ce travail de thèse a également exploré les limites et la faisabilité de l'étude de l'épissage alternatif avec des outils moléculaires basés sur le système CRISPRAlternative splicing of precursor RNA is a co-transcriptional process that affects the vast majority of human genes and contributes to protein diversity. Dysregulation of such process is implicated in various diseases, including tumorigenesis. However, the mechanisms regulating these processes were still to be characterized. In this study, we showed that perturbations of alternative splicing correlated with dysregulations of convergent transcription and DNA methylation. Convergent transcription could be generated between pairs of neighboring genes in opposite orientation, or between intragenic enhancers and their host gene. CENPO and ADCY3 was identified as a convergent transcription gene pair. We found, in a tumor progression model of breast cancer, that the splicing change of the ADCY3 variant exon22 correlated with an increase of its transcription that went against that of CENPO. By using targeted transcription repression system CRISPRi, we demonstrated that downregulating the transcription of CENPO could not reverse the alternative splicing alteration of ADCY3 in cancer cells (DCIS). An active intragenic enhancer was identified in the intron16 of CD44, at the downstream of its alternative exons. By using targeted transcription activation system CRISPRa, we showed that upregulating the transcription of CD44 could not alter the alternative splicing of CD44 in DCIS cells. These results suggest that convergent transcription modulation through changes of promoter activity does not alter the alternative splicing of ADCY3 and CD44 in DCIS cells. However, through replacing the intragenic enhancer by an inducible promoter, we found that intragenic transcription activation increased the inclusion level of several alternative exons of CD44 in HCT116 cells. This result suggested that local convergent transcription could have a direct impact on the alternative splicing of CD44. Furthermore, by using targeted DNA methylation system CRISPR/dCas9-DNMT3b, we showed that DNA methylation at variant exons could directly modify CD44 alternative splicing. This thesis work also explored the limitation and feasibility of studying alternative splicing with repurposed CRISPR systems
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Carvin, Christopher Dumas. "Transcriptional regulation and chromatin remodeling mechanisms at PHO5." Diss., Texas A&M University, 2003. http://hdl.handle.net/1969.1/2193.
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Regulation of gene expression is vital for proper growth and prevention of disease states. In eukaryotes this regulation occurs in the context of chromatin which creates an inherent barrier for the binding of trans-acting factors, such as transcription factors and RNA polymerase. This dissertation focuses on the role of transcriptional activators and chromatin remodeling coactivators in the regulation of the repressible acid phosphatase gene PHO5. Our studies show that histone methylation at lysine 4 of histone H3 is required for the full repression of PHO5and GAL1-10. We show that bromodomains, a domain conserved in chromatin remodeling coactivators, may function to stabilize binding. Finally, we present a strategy using DNA methyltransferases as in vivo probes to detect DNA-protein interactions and examine chromatin structure. We extend this strategy to zinc-finger proteins which can be engineered to bind to any desired DNA sequence as a means of targeting methylation with potential use in epigenetic silencing.
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MARIANI, JESSICA. "Transcriptional regulation, target genes and functional roles of the SOX2 transcription factor in mouse neural stem cells maintenance and neuronal differentiation." Doctoral thesis, Università degli Studi di Milano-Bicocca, 2009. http://hdl.handle.net/10281/8321.
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The aims of this PhD research were: to examine molecular mechanisms underlying the transcriptional regulation of the Sox2 gene during forebrain development; to examine the role of Sox2 for the proper neuronal differentiation of neural stem cells; and to examine the role of Sox2 in controlling the maintenance of neural stem cells (in vivo and in vitro).
The aim of the first work (Chapter 1) was to investigate the transcription factors and the regulatory sequences that control transcription of the Sox2 gene in the developing brain and neural stem cells. Our laboratory previously identified Sox2 regulatory sequences able to drive expression of a reporter β-geo transgene to neural stem cells of the brain in transgenic mice. I focused on two mouse forebrain-specific enhancers able to recapitulate Sox2 telencephalic expression throughout forebrain development, also active in neural stem cells of the adult and embryonic brain (Sox2 5’ and 3’ enhancers). This work showed that Emx2 acts as a direct transcriptional repressor of both Sox2 telencephalic enhancers, acting in two different ways to repress their transcriptional activity: by directly binding to a specific site within these regulatory elements, thus preventing the binding of activators, or possibly by protein to protein interaction sequestring the activators, thus antagonizing their activity. By the study of double mutant mice (expressing reduced levels of Sox2 and Emx2) we further found that Emx2 deficiency counteracts (at least in part) the deleterious effects of Sox2 deficiency on neural stem cell proliferation ability in the postnatal hippocampus, and also rescued other brain morphological abnormalities of Sox2-deficient mutants. It is likely possible that a simultaneous decrease of Emx2 levels (a Sox2 repressor) may antagonize these defects, by restoring Sox2 levels.
In the second line of my research (Chapter 2) we performed in vitro differentiation studies on neural stem cells cultured from embryonic and adult brains of Sox2 “knockdown” mutants (expressing reduced levels of Sox2) where Sox2 deficiency impairs neuronal differentiation. In particular, my contribution to this work was to evaluate the in vitro differentiation defects of Sox2 mutant neurospheres by immunofluorescence staining for different glial and neuronal markers. Strikingly, I observed that mutant cells produce reduced numbers of mature neurons (in particular GABAergic neurons), but generate normal glia. Most of the cells belonging to the neuronal lineage failed to progress to mature neurons showing morphological abnormalities. To evaluate if restoration of Sox2 levels is able to rescue the differentiation defects of mutant cells, I engineered Sox2-expressing lentiviral vector, which I used to infect neural cells at early or late differentiation stages. I found that, Sox2 overexpression is able to rescue the neuronal maturation defects of mutant cells only if administered at early stages of differentiation. Further, I observed that Sox2 suppresses the endogenous GFAP gene, a marker of glial differentiation. These results suggests that Sox2 is required in early in vitro differentiating neuronal cells, for maturation and for suppression of alternative lineage markers.
The third research (Chapter 3) investigated neurogenesis and neural stem cells properties in mice carrying a conditional mutation in the Sox2 gene (Sox2flox). Here, Sox2 was deleted via a nestin-Cre transgene that leads to complete Sox2 loss in the central nervous system by 12.5 dpc. These studies showed that embryonic neurogenesis was not importantly defective, however shortly after birth, NSC and neurogenesis are completely lost in the hippocampus. The expression of cytokine-encoding genes, essential for stem cell niche, is also strongly perturbed and leads to impaired stem cell maintenance (in vivo and in vitro). In vitro, NSC cultures derived from Sox2-deleted forebrain become rapidly exhausted, losing their proliferation and self-renewal properties. In Sox2-deleted neurospheres, Shh is extremely downregulated. However, the conditioned medium from wild type NSC cultures or the administration of a Shh agonist efficiently rescue the proliferation defects. These results suggest that the effect of Sox2 on neural stem cells growth and maintenance is partially mediated by Shh secretion, and that the Shh gene must be a direct target of Sox2. To confirm this hypothesis, I infected Sox2-deleted NSC with a Sox2-IRES-GFP expressing lentivirus just prior to the beginning of the growh decline, and I observed that the re-expression of Sox2 induces the ability to re-express Shh and rescues the formation of neurosphere. These findings indicate that NSC control their status, at least in part, through non cell-autonomous mechanisms (such as activation of important cytochine-encoding genes) which depend on Sox2.
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ZHAO, CHEN. "DECIPHERING TRANSCRIPTIONAL ACTIVITY OF DROSOPHILA BICOID MORPHOGEN: SELECTIVITY AND REGULATION." University of Cincinnati / OhioLINK, 2001. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1006196849.
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Akhmetova, Laila. "Transcriptional Regulation of Nodal Target Genes in Early Zebrafish Development." Thesis, Harvard University, 2016. http://nrs.harvard.edu/urn-3:HUL.InstRepos:33493493.
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Nodal signaling is one of the principal players in the process of gastrulation, during which the primary germ layers (endoderm, mesoderm, and ectoderm) are formed and organized in their proper locations. During my PhD I studied how Smad2 and FoxH1 transcription factors regulate the expression of Nodal target genes, and the relationship between the chromatin state of target genes and their expression.
In order to carry out in depth analysis of FoxH1 function I generated a complete mutant of this transcription factor and used deep sequencing to identify which genes FoxH1 regulates in zebrafish development. Using ChIP-Seq experiments, I also found the binding sites of FoxH1 and found that FoxH1 is capable of binding to genomic DNA in the absence of Nodal signaling. This finding suggests that it may act as a pioneer factor, preparing target genes for rapid activation when gastrulation starts. I also identified 54 direct FoxH1 target genes that are not Nodal-dependent, as well as 13 genes that are repressed, rather than activated, by FoxH1.
To identify Smad2 binding sites, I carried out ChIP-Seq in embryos overexpressing Nodal signal Squint, thus detecting loci that bind Smad2 after exposure to high Nodal levels. I tested the identified Smad2-bound DNA elements for their gene regulatory potential, and discovered that they are sufficient to drive gene expression in a Nodal-dependent manner. I also identified 26 previously unpublished Nodal target genes, and 55 genes that are bound by Smad2 upon exposure to high, but not low levels of Nodal signaling.
In the last chapter I describe the study of the interaction between Nodal signaling in early zebrafish development and chromatin marks. I found that exposure of embryonic cells to high levels of Nodal is associated with low levels of H3K27me3 and high levels of H3K4me3 marks on Nodal target genes, compared to unexposed cells. I also describe a Cas9-based system that we used to change H3K27me3 levels in a targeted manner, and tested it in a developing embryo on a Nodal-responsive fgf8a gene. Our results suggest that reduction of H3K27me3 mark on its own is not sufficient to affect the expression of this gene, and additional mechanisms are involved in target gene activation by Smad2.Biology, Molecular and Cellular
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Bolick, Sophia C. E. "Regulation of transcription and analysis of drug targets in lymphoma and myeloma cells." [Tampa, Fla] : University of South Florida, 2006. http://purl.fcla.edu/usf/dc/et/SFE0001750.
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MARKEY, MICHAEL PATRICK. "TRANSCRIPTIONAL REGULATION BY THE RETINOBLASTOMA TUMOR SUPPRESSOR: NOVEL TARGETS AND MECHANISMS." University of Cincinnati / OhioLINK, 2004. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1092243630.
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Markey, Michael P. "Transcriptional regulation by the retinoblastoma tumor suppressor novel targets and mechanisms /." Cincinnati, Ohio : University of Cincinnati, 2004. http://rave.ohiolink.edu/etdc/view?acc%5Fnum=ucin1092243630.
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Ratanamart, Jarupa. "Immunogenicity, efficiency and transcriptional regulation of plasmin-mediated muscle-targeted insulin gene therapy for diabetes." Thesis, University of Newcastle Upon Tyne, 2006. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.431132.
Full textBooks on the topic "Targeted transcription regulation"
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Ho, Rita Sam Man. Disruption of imprinted transcription regulation of the Mash2 gene by targeted DNA insertion. 2004.
Find full textBook chapters on the topic "Targeted transcription regulation"
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Dixit, Vineeta, and Priti Upadhyay. "Targeted Genome-Editing Techniques in Plant Defense Regulation." In Transcription Factors for Biotic Stress Tolerance in Plants, 1–32. Cham: Springer International Publishing, 2022. http://dx.doi.org/10.1007/978-3-031-12990-2_1.
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Westermarck, Jukka. "Regulation of Transcription Factor Function by Targeted Protein Degradation: An Overview Focusing on p53, c-Myc, and c-Jun." In Methods in Molecular Biology, 31–36. Totowa, NJ: Humana Press, 2010. http://dx.doi.org/10.1007/978-1-60761-738-9_2.
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Kim, Sung-Il, Yogendra Bordiya, Ji-Chul Nam, José Mayorga, and Hong-Gu Kang. "High-Throughput Targeted Transcriptional Profiling of Defense Genes Using RNA-Mediated Oligonucleotide Annealing, Selection, and Ligation with Next-Generation Sequencing in Arabidopsis." In Modeling Transcriptional Regulation, 227–52. New York, NY: Springer US, 2021. http://dx.doi.org/10.1007/978-1-0716-1534-8_15.
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Beach, Dale L., and Jack D. Keene. "Ribotrap: Targeted Purification of RNA-Specific RNPs from Cell Lysates Through Immunoaffinity Precipitation to Identify Regulatory Proteins and RNAs." In Post-Transcriptional Gene Regulation, 69–91. Totowa, NJ: Humana Press, 2008. http://dx.doi.org/10.1007/978-1-59745-033-1_5.
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Brooks, Matthew D., Kelsey M. Reed, Gabriel Krouk, Gloria M. Coruzzi, and Bastiaan O. R. Bargmann. "The TARGET System: Rapid Identification of Direct Targets of Transcription Factors by Gene Regulation in Plant Cells." In Transcription Factor Regulatory Networks, 1–12. New York, NY: Springer US, 2022. http://dx.doi.org/10.1007/978-1-0716-2815-7_1.
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Wang, Chenguang, Jun-Yuan Ji, Lifeng Tian, and Richard G. Pestell. "Transcriptional Regulation of Lipogenesis as a Therapeutic Target for Cancer Treatment." In Nuclear Signaling Pathways and Targeting Transcription in Cancer, 259–75. New York, NY: Springer New York, 2013. http://dx.doi.org/10.1007/978-1-4614-8039-6_10.
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Molesini, Barbara, and Tiziana Pandolfini. "Exogenous application of RNAs as a silencing tool for discovering gene function." In RNAi for plant improvement and protection, 14–24. Wallingford: CABI, 2021. http://dx.doi.org/10.1079/9781789248890.0003.
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Abstract This chapter focuses on the importance of the RNA silencing technique in unraveling the function of genes by inhibiting gene expression at the post-transcriptional level, and is particularly appropriate for studying developmental processes such as fruit setting and growth that require a tight organ/tissue and time-specific regulation of the expression of target genes. Some methods used for establishing the function of a specific gene altering gene expression at either the genomic or post-transcriptional level are also presented.
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Molesini, Barbara, and Tiziana Pandolfini. "Exogenous application of RNAs as a silencing tool for discovering gene function." In RNAi for plant improvement and protection, 14–24. Wallingford: CABI, 2021. http://dx.doi.org/10.1079/9781789248890.0014.
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Abstract This chapter focuses on the importance of the RNA silencing technique in unraveling the function of genes by inhibiting gene expression at the post-transcriptional level, and is particularly appropriate for studying developmental processes such as fruit setting and growth that require a tight organ/tissue and time-specific regulation of the expression of target genes. Some methods used for establishing the function of a specific gene altering gene expression at either the genomic or post-transcriptional level are also presented.
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Paro, Renato, Ueli Grossniklaus, Raffaella Santoro, and Anton Wutz. "Biology of Chromatin." In Introduction to Epigenetics, 1–28. Cham: Springer International Publishing, 2021. http://dx.doi.org/10.1007/978-3-030-68670-3_1.
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AbstractThis chapter provides an introduction to chromatin. We will examine the organization of the genome into a nucleosomal structure. DNA is wrapped around a globular complex of 8 core histone proteins, two of each histone H2A, H2B, H3, and H4. This nucleosomal arrangement is the context in which information can be established along the sequence of the DNA for regulating different aspects of the chromosome, including transcription, DNA replication and repair processes, recombination, kinetochore function, and telomere function. Posttranslational modifications of histone proteins and modifications of DNA bases underlie chromatin-based epigenetic regulation. Enzymes that catalyze histone modifications are considered writers. Conceptually, erasers remove these modifications, and readers are proteins binding these modifications and can target specific functions. On a larger scale, the 3-dimensional (3D) organization of chromatin in the nucleus also contributes to gene regulation. Whereas chromosomes are condensed during mitosis and segregated during cell division, they occupy discrete volumes called chromosome territories during interphase. Looping or folding of DNA can bring regulatory elements including enhancers close to gene promoters. Recent techniques facilitate understanding of 3D contacts at high resolution. Lastly, chromatin is dynamic and changes in histone occupancy, histone modifications, and accessibility of DNA contribute to epigenetic regulation.
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Bunnik, Evelien M., and Karine G. Le Roch. "Mechanisms Regulating Transcription inPlasmodium falciparumas Targets for Novel Antimalarial Drugs." In Comprehensive Analysis of Parasite Biology: From Metabolism to Drug Discovery, 421–40. Weinheim, Germany: Wiley-VCH Verlag GmbH & Co. KGaA, 2016. http://dx.doi.org/10.1002/9783527694082.ch18.
Full textConference papers on the topic "Targeted transcription regulation"
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Ahmad, Salma, Hanan Nazar, Nouralhuda Alatieh, Maryam Al-Mansoob, Zainab Farooq, Muna Yusuf, and Allal Ouhtit. "Validation of Novel Transcriptional Targets that Underpin CD44-promoted breast cancer cell invasion." In Qatar University Annual Research Forum & Exhibition. Qatar University Press, 2021. http://dx.doi.org/10.29117/quarfe.2021.0153.
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Introduction: Breast cancer (BC) is the most common cancer worldwide, and metastasis is its worst aspect and the first cause of death. Metastasis is a multistep process, where an invasion is a recurring event. The process of BC cell invasion involves three major factors, including cell adhesion molecules (CAM), proteinases and Growth factors.CD44, a family of CAM proteins and the hyaluronic acid (HA) cell surface receptor, acts as cell differentiation, cell migration/invasion and apoptosis regulator. Rationale: We have previously established a tetracycline (Tet)-OFF-regulated expression system, both in vitro and in vivo (Hill et al, 2006). As a complementary approach, the highly metastatic MDA-MB-231 BC cells expressing high levels of endogenous CD44s (the standard form of CD44), was cultured in the presence and absence of 50 µg/ml of HA. RNA samples were isolated from both cell experimental models, and microarray analysis (12K CHIP from Affymetrix) was applied. More than 200 CD44s transcriptional target genes were identified and were sub-divided into groups of genes based on their function: cell motility, cytoskeletal organization, ability to degrade ECM, and cell survival. Hypothesis: Among these 200 identified genes, we selected seven genes (ICAP-1, KYNU, AHR, SIRT1, SRSF8, PRAD1, and SOD2) and hypothesized that based on evidence from literature, these genes are potential novel targets of CD44-downstream signaling mediating BC cell invasion. Specific Aims: Pursuant to this goal, we proposed the following objectives: 1- Structural validation of ICAP-1, KYNU, AHR, SIRT1, SRSF8, PRAD1 and SOD2 as novel transcriptional targets of CD44/HA-downstream signaling at both RNA and Protein level using reverse transcription polymerase chain reaction (RT-PCR) and Western Blot respectively. 2-Functional validation of ICAP-1, KYNU, AHR, SIRT1, SRSF8, PRAD1and SOD2 as novel transcriptional targets that underpin CD44-promoted BC cell migration using wound healing assay after the transfection with siRNA. Innovation/Consclusion: This study validated seven transcriptional targets of CD44/HA-downstream signaling promoting BC cell invasion. Ongoing experiments aim to dissect the signaling pathways that link CD44 activation by HA to the transcription of these seven genes.
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Cotter, Kellie, Dimple Chakravarty, Andrea Sboner, and Mark A. Rubin. "Abstract 5042: Dynamic transcriptional regulation of ERα targets in prostate cancer." In Proceedings: AACR 106th Annual Meeting 2015; April 18-22, 2015; Philadelphia, PA. American Association for Cancer Research, 2015. http://dx.doi.org/10.1158/1538-7445.am2015-5042.
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Yamamoto, Kaneyoshi, and Akira Ishihama. "Construction of 'Promoter Chip' for Microarray Analysis of Regulation Targets of Transcription Factors." In 2007 International Symposium on Micro-NanoMechatronics and Human Science. IEEE, 2007. http://dx.doi.org/10.1109/mhs.2007.4420839.
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Park, Byeolna, Yoon Kyeong Lee, and Hak Yong Kim. "Transcriptional regulation of drug target proteins from cancer related disease network." In 2010 IEEE International Conference on Bioinformatics and Biomedicine Workshops (BIBMW). IEEE, 2010. http://dx.doi.org/10.1109/bibmw.2010.5703937.
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Schwentner, Raphaela, Maximilian Kauer, Sven Bilke, Gunhild Jug, Paul S. Meltzer, and Heinrich Kovar. "Abstract 5341: Combinatorial regulation of E2F target genes by the oncogenic ETS transcription factor EWS-FLI1." In Proceedings: AACR 102nd Annual Meeting 2011‐‐ Apr 2‐6, 2011; Orlando, FL. American Association for Cancer Research, 2011. http://dx.doi.org/10.1158/1538-7445.am2011-5341.
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Butt, Sabrina, Timothy J. Stanek, Victoria J. Gennaro, Chris McNair, Kristen L. Pauley, Karen Knudsen, and Steven B. McMahon. "Abstract LB-A29: Divergent mechanisms of transcriptional regulation by SAGA member and epigenetic modifier USP22." In Abstracts: AACR-NCI-EORTC International Conference: Molecular Targets and Cancer Therapeutics; October 26-30, 2017; Philadelphia, PA. American Association for Cancer Research, 2018. http://dx.doi.org/10.1158/1535-7163.targ-17-lb-a29.
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Rodriguez, Esteban Jose Rodriguez, and Rodrigo Mora-Rodriguez. "miR-let-7a-2, miR103a-2 and CREB1-TF as therapeutic targets to regulate the transcription of DISC1 and PDE4D in the transcriptional regulation pathway by DISC1/ATF4 complex." In 2022 IEEE 4th International Conference on BioInspired Processing (BIP). IEEE, 2022. http://dx.doi.org/10.1109/bip56202.2022.10032479.
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Riffo, Elizabeth, Mario Palma, Catalina Alarcon, Ariel Castro, Vicente Torres, and Roxana Pincheira. "Abstract C131: The SALL2 transcription factor promotes cell migration and focal adhesion turnover via regulation of integrin expression." In Abstracts: AACR-NCI-EORTC International Conference on Molecular Targets and Cancer Therapeutics; October 26-30, 2019; Boston, MA. American Association for Cancer Research, 2019. http://dx.doi.org/10.1158/1535-7163.targ-19-c131.
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Barbier, Roberto H., Edel M. McCrea, Jonathan D. Strope, Phoebe A. Huang, Tristan M. Sissung, Douglas K. Price, Cindy H. Chau, and William D. Figg. "Abstract A069: Mechanisms governing the transcriptional regulation of the liver-specific transporter OATP1B3 in prostate cancer." In Abstracts: AACR-NCI-EORTC International Conference on Molecular Targets and Cancer Therapeutics; October 26-30, 2019; Boston, MA. American Association for Cancer Research, 2019. http://dx.doi.org/10.1158/1535-7163.targ-19-a069.
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Goel, Sakshi, Vipul Bhatia, Mahendra Shyamlal Palecha, Shannon Carskadon, Nallasivam Palanisamy, and Bushra Ateeq. "Abstract B124: ERG mediated transcriptional regulation ofDLX1homeobox gene represents a novel mechanism underlying prostate cancer progression." In Abstracts: AACR-NCI-EORTC International Conference on Molecular Targets and Cancer Therapeutics; October 26-30, 2019; Boston, MA. American Association for Cancer Research, 2019. http://dx.doi.org/10.1158/1535-7163.targ-19-b124.
Full textReports on the topic "Targeted transcription regulation"
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Arazi, Tzahi, Vivian Irish, and Asaph Aharoni. Micro RNA Targeted Transcription Factors for Fruit Quality Improvement. United States Department of Agriculture, July 2008. http://dx.doi.org/10.32747/2008.7592651.bard.
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Fruits are unique to flowering plants and represent an important component of human and animal diets. Development and maturation of tomato fruit is a well-programmed process, and yet, only a limited number of factors involved in its regulation have been characterized. Micro-RNAs (miRNAs) are small, endogenous RNAs that regulate gene expression in animals and plants. Plant miRNAs have a vital role in the generation of plant forms through post-transcriptional regulation of the accumulation of developmental regulators, especially transcription factors. Recently, we and others have demonstrated that miRNAs and other type of small RNAs are expressed in tomato fruit, and target putative transcription factors during its development and maturation. The original objectives of the approved proposal were: 1. To identify fruit miRNA transcription factor target genes through a bioinformatic approach. 2. To identify fruit miRNA transcription factor target genes up-regulated in tomato Dicer-like 1 silenced fruit. 3. To establish the biological functions of selected transcription factors and examine their utility for improving fleshy fruit quality trait. This project was approved by BARD as a feasibility study to allow initial experiments to peruse objective 2 as described above in order to provide initial evidence that miRNAs do play a role in fruit development. The approach planned to achieve objective 2, namely to identify miRNA transcription factor targets was to clone and silence the expression of a tomato DCL1 homolog in different stages of fruit development and examine alterations to gene expression in such a fruit in order to identify pathways and target genes that are regulated by miRNA via DCL1. In parallel, we characterized two transcription factors that are regulated by miRNAs in the fruit. We report here on the cloning of tomato DCL1 homolog, characterization of its expression in fruit flesh and peel of wild type and ripening mutants and generation of transgenic plants that silence SlDCL1 specifically in the fruit. Our results suggest that the tomato homolog of DCL1, which is the major plant enzyme involved in miRNA biogenesis, is present in fruit flesh and peel and differentially expressed during various stages of fruit development. In addition, its expression is altered in ripening mutants. We also report on the cloning and expression analysis of Sl_SBP and Sl_ARF transcription factors, which serve as targets of miR157 and miR160, respectively. Our data suggest that Sl_SBP levels are highest during fruit ripening supporting a role for this gene in that process. On the other hand Sl_ARF is strongly expressed in green fruit up to breaker indicating a role for that gene at preripening stage which is consistent with preliminary in_situ analyses that suggest expression in ovules of immature green fruit. The results of this feasibility study together with our previous results that miRNAs are expressed in the fruit indeed provide initial evidence that these regulators and their targets play roles in fruit development and ripening. These genes are expected to provide novel means for genetic improvement of tomato fleshy fruit.
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Grumet, Rebecca, Rafael Perl-Treves, and Jack Staub. Ethylene Mediated Regulation of Cucumis Reproduction - from Sex Expression to Fruit Set. United States Department of Agriculture, February 2010. http://dx.doi.org/10.32747/2010.7696533.bard.
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Reproductive development is a critical determinant of agricultural yield. For species with unisexual flowers, floral secualdifferentation adds additional complexity, that can influenec productivity. The hormone ethylene has long, been known to play a primary role in sex determination in the Cucumis species cucumber (C. sativus) and melon (C. melo). Our objectives were to: (1) Determine critical sites of ethylene production and perception for sex determination; (2) Identify additional ethylene related genes associated with sex expression; and (3) Examine the role of environment ami prior fruit set on sex expression, pistillate flower maturation, and fruit set. We made progress in each of these areas. (1) Transgenic melon produced with the Arabidopsis dominant negative ethylene perception mutant gene, etrl-1, under the control of floral primordia targeted promoters [AP3 (petal and stamen) and CRC (carpel and nectary)], showed that ethylene perception by the stamen primordia, rather than carpel primordia, is critical for carpel development at the time of sex determination. Transgenic melons also were produced with the ethylene production enzyme gene. ACS, encoding l-aminocyclopropane-lcarboylate synthase, fused to the AP3 or CRC promoters. Consistent with the etr1-1 results, CRC::ACS did not increase femaleness; however, AP3::ACS reduced or eliminated male flower production. The effects of AP3:ACS were stronger than those of 35S::ACS plants, demonstratin g the importance of targeted expression, while avoiding disadvantages of constitutive ethylene production. (2) Linkage analysis coupled with SNP discovery was per formed on ethylene and floral development genes in cucumber populations segregating for the three major sex genes. A break-through towards cloning the cucumber M gene occurred when the melon andromonoecious gene (a), an ACS gene, was cloned in 2008. Both cucumber M and melon a suppress stamen development in pistillate flowers. We hypothesized that cucumber M could be orthologous to melon a, and found that mutations in CsACS2 co-segregated perfectly with the M gene. We also sought to identify miRNA molecules associated with sex determination. miRNA159, whose target in Arabidopsis is GAMYB[a transcription factor gene mediating response to10 gibberellin (GA)], was more highly expressed in young female buds than male. Since GA promotes maleness in cucumber, a micro RNA that counteracts GAMYB could promote femaleness. miRNA157, which in other plants targets transcription factors involved in flower development , was expressed in young male buds and mature flower anthers. (3) Gene expression profiling showed that ethylene-, senescence-, stress- and ubiquitin-related genes were up-regulated in senescing and inhibited fruits, while those undergoing successful fruit set up-regulated photosynthesis, respiration and metabolic genes. Melon plants can change sex expression in response to environmental conditions, leading to changes in yield potential. Unique melon lines with varying sex expression were developed and evaluated in the field in Hancock, Wisconsin . Environmental changes during the growing season influenced sex expression in highly inbred melon lines. Collectively these results are of significance for understanding regulation of sex expression. The fact that both cucumber sex loci identified so far (F and M) encode isoforms of the same ethylene synthesis enzyme, underscores the importance of ethylene as the main sex determining hormone in cucumber. The targeting studies give insight into developmental switch points and suggest a means to develop lines with earlier carpel-bearing flower production and fruit set. These results are of significance for understanding regulation of sex expression to facilitate shorter growing seasons and earlier time to market. Field results provide information for development of management strategies for commercial production of melon cultivars with different sex expression characteristics during fruit production.
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Jander, Georg, and Daniel Chamovitz. Investigation of growth regulation by maize benzoxazinoid breakdown products. United States Department of Agriculture, January 2015. http://dx.doi.org/10.32747/2015.7600031.bard.
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Introduction Previous research had suggested that benzoxazinoids, a class of defensive metabolites found in maize, wheat, rye, and wild barley, are not only direct insect deterrents, but also influence other areas of plant metabolism. In particular, the benzoxazinoid 2,4-dihydroxy-7-methoxy-2H-1,4-benzoxa- zin-3(4H)- one (DIMBOA) was implicated in: (i) altering plant growth by interfering with auxin signaling, and (ii) leading to the induction of gene expression changes and secondary plant defense responses. The overall goal of this proposal was to identify mechanisms by which benzoxazinoids influence other aspects of plant growth and defense. Specifically, the following hypotheses were proposed to be tested as part of an approved BARD proposal: Benzoxazinoid breakdown products directly interfere with auxin perception Global changes in maize and barley gene expression are induced by benzoxazinoid activation. There is natural variation in the maize photomorphogenic response to benzoxazinoids. Although the initial proposal included experiments with both maize and barley, there were some technical difficulties with the proposed transgenic barley experiments and most of the experimental results were generated with maize. Summary of major findings Previous research by other labs, involving both maize and other plant species, had suggested that DIMBOA alters plant growth by interfering with auxin signaling. However, experiments conducted in both the Chamovitz and the Jander labs using Arabidopsis and maize, respectively, were unable to confirm previously published reports of exogenously added DIMBOA effects on auxin signaling. Nevertheless, analysis of bx1 and bx2 maize mutant lines, which have almost no detectable benzoxazinoids, showed altered responses to blue light signaling. Transcriptomic analysis of maize mutant lines, variation in inbred lines, and responses to exogenously added DIMBOA showed alteration in the transcription of a blue light receptor, which is required for plant growth responses. This finding provides a novel mechanistic explanation of the trade-off between growth and defense that is often observed in plants. Experiments by the Jander lab and others had demonstrated that DIMBOA not only has direct toxicity against insect pests and microbial pathogens, but also induces the formation of callose in both maize and wheat. In the current project, non-targeted metabolomic assays of wildtype maize and mutants with defects in benzoxazinoid biosynthesis were used to identify unrelated metabolites that are regulated in a benzoxazinoid-dependent manner. Further investigation identified a subset of these DIMBOA-responsive compounds as catechol, as well as its glycosylated and acetylated derivatives. Analysis of co-expression data identified indole-3-glycerol phosphate synthase (IGPS) as a possible regulator of benzoxazinoid biosynthesis in maize. In the current project, enzymatic activity of three predicted maize IGPS genes was confirmed by heterologous expression. Transposon knockout mutations confirmed the function of the maize genes in benzoxazinoid biosynthesis. Sub-cellular localization studies showed that the three maize IGPS proteins are co-localized in the plastids, together with BX1 and BX2, two previously known enzymes of the benzoxazinoid biosynthesis pathway. Implications Benzoxazinoids are among the most abundant and effective defensive metabolites in maize, wheat, and rye. Although there is considerable with-in species variation in benzoxazinoid content, very little is known about the regulation of this variation and the specific effects on plant growth and defense. The results of this research provide further insight into the complex functions of maize benzoxazinoids, which are not only toxic to pests and pathogens, but also regulate plant growth and other defense responses. Knowledge gained through the current project will make it possible to engineer benzoxazinoid biosynthesis in a more targeted manner to produce pest-tolerant crops without negative effects on growth and yield.
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Pichersky, Eran, Alexander Vainstein, and Natalia Dudareva. Scent biosynthesis in petunia flowers under normal and adverse environmental conditions. United States Department of Agriculture, January 2014. http://dx.doi.org/10.32747/2014.7699859.bard.
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The ability of flowering plants to prosper throughout evolution, and for many crop plants to set fruit, is strongly dependent on their ability to attract pollinators. To that end many plants synthesize a spectrum of volatile compounds in their flowers. Scent is a highly dynamic trait that is strongly influenced by the environment. However, with high temperature conditions becoming more common, the molecular interplay between this type of stress and scent biosynthesis need to be investigated. Using petunia as a model system, our project had three objectives: (1) Determine the expression patterns of genes encoding biosynthetic scent genes (BSGs) and of several genes previously identified as encoding transcription factors involved in scent regulation under normal and elevated temperature conditions. (2) Examine the function of petunia transcription factors and a heterologous transcription factor, PAPl, in regulating genes of the phenylpropanoid/benzenoid scent pathway. (3) Study the mechanism of transcriptional regulation by several petunia transcription factors and PAPl of scent genes under normal and elevated temperature conditions by examining the interactions between these transcription factors and the promoters of target genes. Our work accomplished the first two goals but was unable to complete the third goal because of lack of time and resources. Our general finding was that when plants grew at higher temperatures (28C day/22C night, vs. 22C/16C), their scent emission decreased in general, with the exception of a few volatiles such as vanillin. To understand why, we looked at gene transcription levels, and saw that generally there was a good correlation between levels of transcriptions of gene specifying enzymes for specific scent compounds and levels of emission of the corresponding scent compounds. Enzyme activity levels, however, showed little difference between plants growing at different temperature regimes. Plants expressing the heterologous gene PAPl showed general increase in scent emission in control temperature conditions but emission decreased at the higher temperature conditions, as seen for control plants. Finally, expression of several transcription factor genes decreased at high temperature, but expression of new transcription factor, EOB-V, increased, implicating it in the decrease of transcription of BSGs. The major conclusion of this work is that high temperature conditions negatively affect scent emission from plants, but that some genetic engineering approaches could ameliorate this problem.
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Gal-On, Amit, Shou-Wei Ding, Victor P. Gaba, and Harry S. Paris. role of RNA-dependent RNA polymerase 1 in plant virus defense. United States Department of Agriculture, January 2012. http://dx.doi.org/10.32747/2012.7597919.bard.
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Objectives: Our BARD proposal on the impact of RNA-dependent RNA polymerase 1 (RDR1) in plant defense against viruses was divided into four original objectives. 1. To examine whether a high level of dsRNA expression can stimulate RDR1 transcription independent of salicylic acid (SA) concentration. 2. To determine whether the high or low level of RDR1 transcript accumulation observed in virus resistant and susceptible cultivars is associated with viral resistance and susceptibility. 3. To define the biogenesis and function of RDR1-dependent endogenous siRNAs. 4. To understand why Cucumber mosaic virus (CMV) can overcome RDR1-dependent resistance. The objectives were slightly changed due to the unique finding that cucumber has four different RDR1 genes. Background to the topic: RDR1 is a key plant defense against viruses. RDR1 is induced by virus infection and produces viral and plant dsRNAs which are processed by DICERs to siRNAs. siRNAs guide specific viral and plant RNA cleavage or serve as primers for secondary amplification of viral-dsRNA by RDR. The proposal is based on our preliminary results that a. the association of siRNA and RDR1 accumulation with multiple virus resistance, and b. that virus infection induced the RDR1-dependent production of a new class of endogenous siRNAs. However, the precise mechanisms underlying RDR1 induction and siRNA biogenesis due to virus infection remain to be discovered in plants. Major conclusions, solutions and achievements: We found that in the cucurbit family (cucumber, melon, squash, watermelon) there are 3-4 RDR1 genes not documented in other plant families. This important finding required a change in the emphasis of our objectives. We characterized 4 RDR1s in cucumber and 3 in melon. We demonstrated that in cucumber RDR1b is apparently a new broad spectrum virus resistance gene, independent of SA. In melon RDR1b is truncated, and therefore is assumed to be the reason that melon is highly susceptible to many viruses. RDR1c is dramatically induced due to DNA and RNA virus infection, and inhibition of RDR1c expression led to increased virus accumulation which suggested its important on gene silencing/defense mechanism. We show that induction of antiviral RNAi in Arabidopsis is associated with production of a genetically distinct class of virus-activated siRNAs (vasiRNAs) by RNA dependent RNA polymerase-1 targeting hundreds of host genes for RNA silencing by Argonaute-2. Production of vasiRNAs is induced by viruses from two different super groups of RNA virus families, targeted for inhibition by CMV, and correlated with virus resistance independently of viral siRNAs. We propose that antiviral RNAi activate broad-spectrum antiviral activity via widespread silencing of host genes directed by vasiRNAs, in addition to specific antiviral defense Implications both scientific and agricultural: The RDR1b (resistance) gene can now be used as a transcription marker for broad virus resistance. The discovery of vasiRNAs expands the repertoire of siRNAs and suggests that the siRNA-processing activity of Dicer proteins may play a more important role in the regulation of plant and animal gene expression than is currently known. We assume that precise screening of the vasiRNA host targets will lead in the near future for identification of plant genes associate with virus diseases and perhaps other pathogens.
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Barg, Rivka, Erich Grotewold, and Yechiam Salts. Regulation of Tomato Fruit Development by Interacting MYB Proteins. United States Department of Agriculture, January 2012. http://dx.doi.org/10.32747/2012.7592647.bard.
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Background to the topic: Early tomato fruit development is executed via extensive cell divisions followed by cell expansion concomitantly with endoreduplication. The signals involved in activating the different modes of growth during fruit development are still inadequately understood. Addressing this developmental process, we identified SlFSM1 as a gene expressed specifically during the cell-division dependent stages of fruit development. SlFSM1 is the founder of a class of small plant specific proteins containing a divergent SANT/MYB domain (Barg et al 2005). Before initiating this project, we found that low ectopic over-expression (OEX) of SlFSM1 leads to a significant decrease in the final size of the cells in mature leaves and fruits, and the outer pericarp is substantially narrower, suggesting a role in determining cell size and shape. We also found the interacting partners of the Arabidopsis homologs of FSM1 (two, belonging to the same family), and cloned their tomato single homolog, which we named SlFSB1 (Fruit SANT/MYB–Binding1). SlFSB1 is a novel plant specific single MYB-like protein, which function was unknown. The present project aimed at elucidating the function and mode of action of these two single MYB proteins in regulating tomato fruit development. The specific objectives were: 1. Functional analysis of SlFSM1 and its interacting protein SlFSB1 in relation to fruit development. 2. Identification of the SlFSM1 and/or SlFSB1 cellular targets. The plan of work included: 1) Detailed phenotypic, histological and cellular analyses of plants ectopically expressing FSM1, and plants either ectopically over-expressing or silenced for FSB1. 2) Extensive SELEX analysis, which did not reveal any specific DNA target of SlFSM1 binding, hence the originally offered ChIP analysis was omitted. 3) Genome-wide transcriptional impact of gain- and loss- of SlFSM1 and SlFSB1 function by Affymetrix microarray analyses. This part is still in progress and therefore results are not reported, 4) Search for additional candidate partners of SlFSB1 revealed SlMYBI to be an alternative partner of FSB1, and 5) Study of the physical basis of the interaction between SlFSM1 and SlFSB1 and between FSB1 and MYBI. Major conclusions, solutions, achievements: We established that FSM1 negatively affects cell expansion, particularly of those cells with the highest potential to expand, such as the ones residing inner to the vascular bundles in the fruit pericarp. On the other hand, FSB1 which is expressed throughout fruit development acts as a positive regulator of cell expansion. It was also established that besides interacting with FSM1, FSB1 interacts also with the transcription factor MYBI, and that the formation of the FSB1-MYBI complex is competed by FSM1, which recognizes in FSB1 the same region as MYBI does. Based on these findings a model was developed explaining the role of this novel network of the three different MYB containing proteins FSM1/FSB1/MYBI in the control of tomato cell expansion, particularly during fruit development. In short, during early stages of fruit development (Phase II), the formation of the FSM1-FSB1 complex serves to restrict the expansion of the cells with the greatest expansion potential, those non-dividing cells residing in the inner mesocarp layers of the pericarp. Alternatively, during growth phase III, after transcription of FSM1 sharply declines, FSB1, possibly through complexing with the transcription factor MYBI serves as a positive regulator of the differential cell expansion which drives fruit enlargement during this phase. Additionally, a novel mechanism was revealed by which competing MYB-MYB interactions could participate in the control of gene expression. Implications, both scientific and agricultural: The demonstrated role of the FSM1/FSB1/MYBI complex in controlling differential cell growth in the developing tomato fruit highlights potential exploitations of these genes for improving fruit quality characteristics. Modulation of expression of these genes or their paralogs in other organs could serve to modify leaf and canopy architecture in various crops.
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Whitham, Steven A., Amit Gal-On, and Victor Gaba. Post-transcriptional Regulation of Host Genes Involved with Symptom Expression in Potyviral Infections. United States Department of Agriculture, June 2012. http://dx.doi.org/10.32747/2012.7593391.bard.
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Understanding how RNA viruses cause disease symptoms in their hosts is expected to provide information that can be exploited to enhance modern agriculture. The helper component-proteinase (HC-Pro) protein of potyviruses has been implicated in symptom development. Previously, we demonstrated that symptom expression is associated with binding of duplex small-interfering-RNA (duplex-siRNA) to a highly conserved FRNK amino acid motif in the HC-Pro of Zucchini yellow mosaic virus (ZYMV). This binding activity also alters host microRNA (miRNA) profiles. In Turnip mosaic virus (TuMV), which infects the model plant Arabidopsis, mutation of the FRNK motif to FINK was lethal providing further indication of the importance of this motif to HC-Pro function. In this continuation project, our goal was to further investigate how ZYMV and TuMV cause the mis-expression of genes in cucurbits and Arabidopsis, respectively, and to correlate altered gene expression with disease symptoms. Objective 1 was to examine the roles of aromatic and positively charged residues F164RNH and K215RLF adjacent to FR180NK in small RNA binding. Objective 2 was to determine the target genes of the miRNAs which change during HC-Pro expression in infected tissues and transgenic cucumber. Objective 3 was to characterize RNA silencing mechanisms underlying differential expression of host genes. Objective 4 was to analyze the function of miRNA target genes and differentially expressed genes in potyvirus-infected tissues. We found that the charged K/R amino acid residues in the FKNH and KRLF motifs are essential for virus viability. Replacement of K to I in FKNH disrupted duplex-siRNA binding and virus infectivity, while in KRLF mutants duplex-siRNA binding was maintained and virus infectivity was limited: symptomless following a recovery phenomenon. These findings expanded the duplex-siRNA binding activity of HC-Pro to include the adjacent FRNK and FRNH sites. ZYMV causes many squash miRNAs to hyper-accumulate such as miR166, miR390, mir168, and many others. Screening of mir target genes showed that only INCURVATA-4 and PHAVOLUTA were significantly upregulated following ZYMVFRNK infection. Supporting this finding, we found similar developmental symptoms in transgenic Arabidopsis overexpressing P1-HC-Pro of a range of potyviruses to those observed in miR166 mutants. We characterized increased transcription of AGO1 in response to infection with both ZYMV strains. Differences in viral siRNA profiles and accumulation between mild and severe virus infections were characterized by Illumina sequencing, probably due to the differences in HC-Pro binding activity. We determined that the TuMV FINK mutant could accumulate and cause symptoms in dcl2 dcl4 or dcl2 dcl3 dcl4 mutants similar to TuMV FRNK in wild type Arabidopsis plants. These dcl mutant plants are defective in antiviral defenses, and the results show that factors other than HC-ProFRNK motif can induce symptoms in virus-infected plants. As a result of this work, we have a better understanding of the FRNK and FKNH amino acid motifs of HC-Pro and their contributions to the duplex-siRNA binding functions. We have identified plant genes that potentially contribute to infectivity and symptoms of virus infected plants when they are mis-expressed during potyviral infections. The results establish that there are multiple underlying molecular mechanisms that lead viral pathogenicity, some dependent on HC-Pro. The potential benefits include the development of novel strategies for controlling diseases caused by viruses, methods to ensure stable expression of transgenes in genetically improved crops, and improved potyvirus vectors for expression of proteins or peptides in plants.
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Fromm, Hillel, Paul Michael Hasegawa, and Aaron Fait. Calcium-regulated Transcription Factors Mediating Carbon Metabolism in Response to Drought. United States Department of Agriculture, June 2013. http://dx.doi.org/10.32747/2013.7699847.bard.
Full textAbstract:
Original objectives: The long-term goal of the proposed research is to elucidate the transcription factors, genes and metabolic networks involved in carbon metabolism and partitioning in response to water deficit. The proposed research focuses on the GTLcalcium/calmodulinbindingTFs and the gene and metabolic networks modulated by these TFs in Arabidopsis thaliana. The specific objectives are as follows. Objective-1 (USA): Physiological analyses of GTL1 loss- and gain-of-function plants under water sufficient and drought stress conditions Objective 2 (USA / Israel-TAU): Characterizion of GTL target genes and bioinformatic analysis of data to eulcidate gene-network topology. Objective-3 (Israel-TAU): Regulation of GTLmediated transcription by Ca²⁺/calmodulin: mechanism and biological significance. Objective-4 (Israel-BGU): Metabolic networks and carbon partitioning in response to drought. Additional direction: In the course of the project we added another direction, which was reported in the 2nd annual report, to elucidate genes controlling drought avoidance. The TAU team has isolated a few unhydrotropic (hyd) mutants and are in the process of mapping these mutations (of hyd13 and hyd15; see last year's report for a description of these mutants under salt stress) in the Arabidopsis genome by map-based cloning and deep sequencing. For this purpose, each hyd mutant was crossed with a wild type plant of the Landsberg ecotype, and at the F2 stage, 500-700 seedlings showing the unhydrotropic phenotype were collected separately and pooled DNA samples were subkected to the Illumina deep sequencing technology. Bioinformatics were used to identify the exact genomic positions of the mutations (based on a comparison of the genomic sequences of the two Arabidopsis thaliana ecotypes (Columbia and Landsberg). Background: To feed the 9 billion people or more, expected to live on Earth by the mid 21st century, the production of high-quality food must increase substantially. Based on a 2009 Declaration of the World Summit on Food Security, a target of 70% more global food production by the year 2050 was marked, an unprecedented food-production growth rate. Importantly, due to the larger areas of low-yielding land globally, low-yielding environments offer the greatest opportunity for substantial increases in global food production. Nowadays, 70% of the global available water is used by agriculture, and 40% of the world food is produced from irrigated soils. Therefore, much needs to be done towards improving the efficiency of water use by plants, accompanied by increased crop yield production under water-limiting conditions. Major conclusions, solutions and achievements: We established that AtGTL1 (Arabidopsis thaliana GT-2 LIKE1) is a focal determinant in water deficit (drought) signaling and tolerance, and water use efficiency (WUE). The GTL1 transcription factor is an upstream regulator of stomatal development as a transrepressor of AtSDD1, which encodes a subtilisin protease that activates a MAP kinase pathway that negatively regulates stomatal lineage and density. GTL1 binds to the core GT3 cis-element in the SDD1 promoter and transrepresses its expression under water-sufficient conditions. GTL1 loss-of-function mutants have reduced stomatal number and transpiration, and enhanced drought tolerance and WUE. In this case, higher WUE under water sufficient conditions occurs without reduction in absolute biomass accumulation or carbon assimilation, indicating that gtl1-mediated effects on stomatal conductance and transpiration do not substantially affect CO₂ uptake. These results are proof-of-concept that fine-tuned regulation of stomatal density can result in drought tolerance and higher WUE with maintenance of yield stability. Implications: Accomplishments during the IS-4243-09R project provide unique tools for continued discovery research to enhance plant drought tolerance and WUE.
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Eshed-Williams, Leor, and Daniel Zilberman. Genetic and cellular networks regulating cell fate at the shoot apical meristem. United States Department of Agriculture, January 2014. http://dx.doi.org/10.32747/2014.7699862.bard.
Full textAbstract:
The shoot apical meristem establishes plant architecture by continuously producing new lateral organs such as leaves, axillary meristems and flowers throughout the plant life cycle. This unique capacity is achieved by a group of self-renewing pluripotent stem cells that give rise to founder cells, which can differentiate into multiple cell and tissue types in response to environmental and developmental cues. Cell fate specification at the shoot apical meristem is programmed primarily by transcription factors acting in a complex gene regulatory network. In this project we proposed to provide significant understanding of meristem maintenance and cell fate specification by studying four transcription factors acting at the meristem. Our original aim was to identify the direct target genes of WUS, STM, KNAT6 and CNA transcription factor in a genome wide scale and the manner by which they regulate their targets. Our goal was to integrate this data into a regulatory model of cell fate specification in the SAM and to identify key genes within the model for further study. We have generated transgenic plants carrying the four TF with two different tags and preformed chromatin Immunoprecipitation (ChIP) assay to identify the TF direct target genes. Due to unforeseen obstacles we have been delayed in achieving this aim but hope to accomplish it soon. Using the GR inducible system, genetic approach and transcriptome analysis [mRNA-seq] we provided a new look at meristem activity and its regulation of morphogenesis and phyllotaxy and propose a coherent framework for the role of many factors acting in meristem development and maintenance. We provided evidence for 3 different mechanisms for the regulation of WUS expression, DNA methylation, a second receptor pathway - the ERECTA receptor and the CNA TF that negatively regulates WUS expression in its own domain, the Organizing Center. We found that once the WUS expression level surpasses a certain threshold it alters cell identity at the periphery of the inflorescence meristem from floral meristem to carpel fate [FM]. When WUS expression highly elevated in the FM, the meristem turn into indeterminate. We showed that WUS activate cytokinine, inhibit auxin response and represses the genes required for root identity fate and that gradual increase in WUCHEL activity leads to gradual meristem enlargement that affect phyllotaxis. We also propose a model in which the direction of WUS domain expansion laterally or upward affects meristem structure differently. We preformed mRNA-seq on meristems with different size and structure followed by k-means clustering and identified groups of genes that are expressed in specific domains at the meristem. We will integrate this data with the ChIP-seq of the 4 TF to add another layer to the genetic network regulating meristem activity.
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Ohad, Nir, and Robert Fischer. Regulation of Fertilization-Independent Endosperm Development by Polycomb Proteins. United States Department of Agriculture, January 2004. http://dx.doi.org/10.32747/2004.7695869.bard.
Full textAbstract:
Arabidopsis mutants that we have isolated, encode for fertilization-independent endosperm (fie), fertilization-independent seed2 (fis2) and medea (mea) genes, act in the female gametophyte and allow endosperm to develop without fertilization when mutated. We cloned the FIE and MEA genes and showed that they encode WD and SET domain polycomb (Pc G) proteins, respectively. Homologous proteins of FIE and MEA in other organisms are known to regulate gene transcription by modulating chromatin structure. Based on our results, we proposed a model whereby both FIE and MEA interact to suppress transcription of regulatory genes. These genes are transcribed only at proper developmental stages, as in the central cell of the female gametophyte after fertilization, thus activating endosperm development. To test our model, the following questions were addressed: What is the Composition and Function of the Polycomb Complex? Molecular, biochemical, genetic and genomic approaches were offered to identify members of the complex, analyze their interactions, and understand their function. What is the Temporal and Spatial Pattern of Polycomb Proteins Accumulation? The use of transgenic plants expressing tagged FIE and MEA polypeptides as well as specific antibodies were proposed to localize the endogenous polycomb complex. How is Polycomb Protein Activity Controlled? To understand the molecular mechanism controlling the accumulation of FIE protein, transgenic plants as well as molecular approaches were proposed to determine whether FIE is regulated at the translational or posttranslational levels. The objectives of our research program have been accomplished and the results obtained exceeded our expectation. Our results reveal that fie and mea mutations cause parent-of-origin effects on seed development by distinct mechanisms (Publication 1). Moreover our data show that FIE has additional functions besides controlling the development of the female gametophyte. Using transgenic lines in which FIE was not expressed or the protein level was reduced during different developmental stages enabled us for the first time to explore FIE function during sporophyte development (Publication 2 and 3). Our results are consistent with the hypothesis that FIE, a single copy gene in the Arabidopsis genome, represses multiple developmental pathways (i.e., endosperm, embryogenesis, shot formation and flowering). Furthermore, we identified FIE target genes, including key transcription factors known to promote flowering (AG and LFY) as well as shoot and leaf formation (KNAT1) (Publication 2 and 3), thus demonstrating that in plants, as in mammals and insects, PcG proteins control expression of homeobox genes. Using the Yeast two hybrid system and pull-down assays we demonstrated that FIE protein interact with MEA via the N-terminal region (Publication 1). Moreover, CURLY LEAF protein, an additional member of the SET domain family interacts with FIE as well. The overlapping expression patterns of FIE, with ether MEA or CLF and their common mutant phenotypes, demonstrate the versatility of FIE function. FIE association with different SET domain polycomb proteins, results in differential regulation of gene expression throughout the plant life cycle (Publication 3). In vitro interaction assays we have recently performed demonstrated that FIE interacts with the cell cycle regulatory component Retinobalsoma protein (pRb) (Publication 4). These results illuminate the potential mechanism by which FIE may restrain embryo sac central cell division, at least partly, through interaction with, and suppression of pRb-regulated genes. The results of this program generated new information about the initiation of reproductive development and expanded our understanding of how PcG proteins regulate developmental programs along the plant life cycle. The tools and information obtained in this program will lead to novel strategies which will allow to mange crop plants and to increase crop production.