Dissertations / Theses on the topic 'L-typa calcium channels'
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1
Peterson, Blaise. "Molecular determinants of dihydropyridine binding on L-type calcium channels /." Thesis, Connect to this title online; UW restricted, 1996. http://hdl.handle.net/1773/6269.
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Wang, Ming Chuan. "Structural studies of L-type voltage-gated calcium channels." Thesis, University of Manchester, 2005. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.525174.
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Cifelli, Carlo. "Impairment of force development in K(ATP) channel deficient skeletal muscle involves calcium ion influx through L-type calcium ion channels." Thesis, University of Ottawa (Canada), 2006. http://hdl.handle.net/10393/27342.
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ATP-sensitive potassium (KATP) channels link membrane excitability to metabolism. They are regulated by intracellular nucleotides and other factors, and have been shown to play a role in development of skeletal muscle force, but controversy surrounds their role during fatigue. The aim of this research project was to determine the role of KATP channel under conditions that allow for better assessment of changes in force during fatigue, by virtue of using a smaller whole muscle model less subject to anoxia. Thus, the first objective was to determine the effect of the loss of KATP channel activity on force during fatigue in small FDB muscle bundles. KATP channel deficient fibers had faster and greater decreases in peak tetanic force during fatigue, developed greater resting tension, and had lower force recovery following fatigue compared to control wild type muscles. The second objective was to determine whether the functional impairment in skeletal muscle without KATP channel activity was due to an increase in Ca 2+ influx. When [Ca2+]e was reduced or L-type Ca2+ channels partially blocked, Kir6.2-/- FDB muscle had slower fatigue development, less resting tension, and had an improved force recovery.
A novel phenomenon was observed while studying the effect of KATP channel activity in vitro. During a second bout of fatigue the decrease in peak tension was significantly lower than the decrease during the first bout of fatigue. Furthermore, the deleterious effects of the loss of KATP channel activity during an initial fatigue were absent during the second fatigue in FDB exposed to glibenclamide.
It is concluded (i) that the KATP channel is important to prevent impairment of function during fatigue, (ii) that this impairment of function is due to an increase in Ca2+ influx through L-type Ca2+ channels, causing Ca2+ overload, and (iii) that fatigue resistance increases while the dependency on the KATP channel to prevent function impairment and fiber damage decreases following one fatigue bout at 37°C; a phenomenon here termed fatigue pre-conditioning.
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Xu, Man. "Functional roles of L-type calcium channels in murine embryonic hearts." [S.l.] : [s.n.], 2004. http://deposit.ddb.de/cgi-bin/dokserv?idn=970967667.
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Shao, Ying. "Molecular natures of L-type CAv1.2 (alpha1C) and T-type CAv3.2 (alpha1H) voltage sensitive calcium channels (VSCCs) in mouse osteoblasts and mouse bones." Access to citation, abstract and download form provided by ProQuest Information and Learning Company; downloadable PDF file, 169 p, 2005. http://proquest.umi.com/pqdweb?did=954050631&sid=5&Fmt=2&clientId=8331&RQT=309&VName=PQD.
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Crump, Shawn M. "THE CARDIAC L-TYPE CALCIUM CHANNEL DISTAL CARBOXYL- TERMINUS AUTO-INHIBITION IS REGULATED BY CALCIUM." UKnowledge, 2012. http://uknowledge.uky.edu/physiology_etds/5.
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The L-type calcium channel (LTCC) provides trigger Ca2+ for sarcoplasmic reticulum Ca2+-release and LTCC function is influenced by interacting proteins including the LTCC Distal Carboxyl-terminus (DCT) and calmodulin. DCT is proteolytically cleaved, and re-associates with the LTCC complex to regulate calcium channel function. DCT reduces LTCC barium current (IBa,L) in reconstituted channel complexes, yet the contribution of DCT to ICa,L in cardiomyocyte systems is unexplored. This study tests the hypothesis that DCT attenuates cardiomyocyte ICa,L. We measured LTCC current and Ca2+ transients with DCT co-expressed in murine cardiomyocytes. We also heterologously co-expressed DCT and CaV1.2 constructs with truncations corresponding to the predicted proteolytic cleavage site, CaV1.2Δ1801, and a shorter deletion corresponding to well-studied construct, CaV1.2Δ1733. DCT inhibited IBa,L in cardiomyocytes, and in HEK 293 cells expressing CaV1.2Δ1801 and CaV1.2Δ1733. Ca2+-CaM relieved DCT block in cardiomyocytes and HEK cells. The selective block of IBa,L combined with Ca2+-CaM effects suggested that DCT-mediated blockade may be relieved under conditions of elevated Ca2+. We therefore tested the hypothesis that DCT block is dynamic, increasing under relatively low Ca2+, and show that DCT reduced diastolic Ca2+ at low stimulation frequencies but spared high frequency Ca2+-entry. DCT reduction of diastolic Ca2+ and relief of block at high pacing frequencies, and under conditions of supraphysiological bath Ca2+ suggests that a physiological function of DCT is to increase the dynamic range of Ca2+ transients in response to elevated pacing frequencies. Our data motivates the new hypothesis that DCT is a native reverse use-dependent inhibitor of LTCC current.
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Byse, Miranda Jean. "THE ROLE OF THE L-TYPE CALCIUM CHANNEL AND ITS CARBOXYL-TERMINUS." UKnowledge, 2010. http://uknowledge.uky.edu/gradschool_diss/20.
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In the heart, the primary role of the L-type calcium channel (LTCC) CaV1.2 is to conduct calcium into cardiomyocytes and initiate contraction. However, part of the CaV1.2 channel itself, the cleaved carboxyl-terminus (CCt) can also localize to the nucleus and regulate gene transcription. Therefore, the goal of this dissertation project was to determine the role and regulation of CCt in the embryonic and adult heart. The global hypothesis of my dissertation project is that CCt localizes to the nucleus in embryonic and adult cardiomyocytes via a calcium-mediated mechanism and regulates transcription. A model of pharmacological LTCC block-induced perturbation of murine embryonic heart development was first utilized to study the role of CCt. Pharmacological block at embryonic day 10 perturbed cardiogenesis and increased CaV1.2 expression. This result was not mimicked by removal of extracellular calcium or inhibition of calcium release from the sarcoplasmic reticulum. Co-currently, pharmacological block decreased CCt nuclear localization in embryonic cardiomyocytes. At the transcriptional level, CCt suppressed the CaV1.2 promoter. This indicated that the observed upregulation of CaV1.2 induced by pharmacological block may be caused by nuclear localization of the transcriptional repressor, CCt. Therefore, the conclusion was made that pharmacological LTCC block perturbed embryonic cardiogenesis by decreasing nuclear localization of the transcription factor CCt; implying a role for CCt in embryonic heart development. Next, CCt regulation was studied in the adult heart. Similar to the embryonic heart, pharmacological LTCC block decreased nuclear localization of CCt. Inhibition of the calcium activated phosphatase calcineurin also decreased CCt nuclear localization. To determine a role for CCt in the adult heart, CCt nuclear localization was measured in response to hypertrophic stimuli. Serum-induced cardiomyocyte hypertrophy significantly increased nuclear localization of CCt. In conclusion, this dissertation supports the hypothesis that CCt localizes to the nucleus in embryonic and adult cardiomyocytes, and that this regulation is mediated by calcium entry into the cardiomyocyte. Furthermore, data from this dissertation suggests that CCt nuclear localization may play an important role in embryonic heart development and adult cardiac hypertrophy.
8
Pang, Chunyan. "REGULATION OF L-TYPE VOLTAGE-DEPENDNET CALCIUM CHANNELS BY THE REM GTPASE." UKnowledge, 2008. http://uknowledge.uky.edu/gradschool_diss/656.
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The Rem, Rem2, Rad, and Gem/Kir GTPases, comprise a novel subfamily of the small Ras-related GTP-binding proteins known as the RGK GTPases, and have been shown to function as potent negative regulators of high voltage-activated (HVA) Ca2+ channels upon overexpression. HVA Ca2+ channels modulate Ca2+ influx in response to membrane depolarization to regulate a wide variety of cellular functions and they minimally consist of a pore-forming α1 subunit, an intracellular β subunit, and a transmembrane complex α2/δ subunit. While the mechanisms underlying RGK-mediated Ca2+ channel regulation remain poorly defined, it appears that both membrane localization and the binding of accessory Ca2+ channel β subunits (CaVβ) are required for suppression of Ca2+ channel currents. We identified a direct interaction between Rem and the L-type Cavα1 C-terminus (CCT), but not the CCT from CaV3.2 T-type channels. Deletion mapping studies suggest that the conserved CB-IQ domain is required for Rem:CCT association, a region known to contribute to both Ca2+-dependent channel inactivation and facilitation through interactions of Ca2+-bound calmodulin (CaM) with the proximal CCT. Furthermore, both Rem2 and Rad GTPases display similar patterns of CCT binding, suggesting that CCT represents a common binding partner for all RGK proteins. While previous studies have found that association of the Rem C-terminus with the plasma membrane is required for channel inhibition, it is not required for CaVβ- subunit binding. However, Rem:CCT association is well correlated with the plasma membrane localization of Rem and more importantly, Rem-mediated channel inhibition upon overexpression. Moreover, co-expression of the proximal CB-IQ containing region of CCT (residues 1507-1669) in HIT-T15 cells partially relieves Rem blockade of ionic current. Interestingly, Ca2+/CaM disrupts Rem:CCT association in vitro. Moreover, CaM overexpression partially relieves Rem-mediated L-type Ca2+ channel inhibition and Rem overexpression alters the kinetics of calcium-dependent inactivation. Together, these data suggest that the association of Rem with the CCT represents a crucial molecular determinant for Rem-mediated L-type Ca2+ channel regulation and provides new insights into this novel channel regulatory process. These studies also suggest that instead of acting as complete Ca2+ channel blockers, RGK proteins may function as endogenous regulators for the channel inactivation machinery.
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Milholland, Rebecca. "L-type calcium channels mediate nicotinic acetylcholine receptor aggregation on cultured myotubes." Diss., The University of Arizona, 2003. http://hdl.handle.net/10150/280370.
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In this dissertation, I have presented new information on several aspects of the signaling pathway responsible for the clustering of AChRs on muscle cells. First, I have shown that activation of L-CaChs is both necessary for agrin induced clustering of AChRs and sufficient to stimulate AChR clustering even in the absence of agrin. Additionally, I have shown that activation of AChRs causes their own clustering by influencing the activity of L-CaChs. I have also shown that neither AChRs nor L-CaChs play a role in MuSK activation or AChR beta subunit phosphorylation suggesting that the role of AChR and L-CaCh is downstream of MuSK activation and phosphorylation of the AChR beta subunit in the signaling cascade that leads to the aggregation of AChRs. Finally, I have shown that calcium induced clustering and phosphorylation of AChRs require LCaCh activation. These data suggested that although L-CaCh activation is insufficient to cause AChR beta subunit phosphorylation L-CaCh may modulate an intermediate step between MuSK activation and AChR phosphorylation. These data therefore support the hypothesis that L-CaCh activation delivers extracellular calcium to the intracellular machinery that regulates AChR clustering. Furthermore, these data establish the position of L-CaChs in the signaling hierarchy responsible for AChR clustering as being downstream of or parallel to both MuSK activation and AChR phosphorylation in the signaling cascade behind AChR clustering. The data presented in this paper begin to provide an integrated view of NMJ formation in which neuromuscular transmission, calcium signaling, and signaling cascades mediated by neurotrophic factors act in concert to regulate the localization of synaptic molecules to junctional regions of the muscle fiber. Many questions remain, however, regarding the events downstream of MuSK and L-CaCh activation.
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Waite, Sarah. "Regulation of myometrial contractility : defining the contribution of the MaxiK potassium channel and the L- and T-type calcium channels." Thesis, University of Sheffield, 2015. http://etheses.whiterose.ac.uk/11621/.
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This thesis describes a comprehensive study investigating the roles of the MaxiK potassium channel (KCNMA1), L-Type calcium channel (CACNA1C) and T-Type calcium channel (CACNA1G) in the maintenance of quiescence (relaxed myometrium), the preparation for parturition (non-contracting myometrium) and the regulation of the co-ordinated contractions characteristic of parturition itself (contracting myometrium). The role of these channels was investigated using primary human myometrial cell cultures under relaxed, non-contracting and contracting conditions. Protein studies revealed changes in both the amount and channel isoforms expressed between the different conditions. Protein-protein interaction studies revealed that the KCNMA1 and CACNA1C associated with Caveolin-1, Gαs and β2-Adrenergic Receptor. RNA studies revealed that the different incubation conditions modified expression of total channel mRNA and that of various splice variants. Previous research has demonstrated that the CACNA1C channel C-terminus can function as a transcription factor termed CCAT. Within this thesis inmmunohistochemistry staining and protein localisation studies revealed nuclear localisation of both the CACNA1C and KCNMA1 C-terminii. Therefore, genomic studies were undertaken utilising the ChIP assay, coupled with ChIP sequencing, to study the role of the KCNMA1 channel as a transcription factor. Chip-sequencing data files were then analysed using Galaxy, an open access web-based platform. Peak calling generated 47 peaks, 21 were successfully mapped to known genes, including RB1, JPH2 and MAP3K7. Motif discovery was then undertaken for both the KCNMA1 protein utilising GYM and the successfully mapped peaks using the Panoptic Motif Search Tool. A helix-turn-helix motif was discovered in the C-terminal region of the KCNMA1 protein and ten putative transcription factor binding motifs were discovered within the peak regions. The significance of these findings is discussed.
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Walsh, Conor P. "3D Structures of L-type and T-type voltage-gated calcium channels in the heart." Thesis, University of Manchester, 2009. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.509725.
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Luin, Elisa. "The Ca 2+ currents and homeostasis during the aging process of skeletal muscle." Doctoral thesis, Università degli studi di Trieste, 2008. http://hdl.handle.net/10077/2574.
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2006/2007Aims: The mechanisms involved in sarcopenia, the decline in muscle mass with aging coupled with loss of force and function, has been actively investigated in animal and human models over the last years [reviewed in Di Iorio et al., Sarcopenia: age-related skeletal muscle changes from determinants to physical disability, Int. J. Immunopathol. Pharmacol. 19 (2006) 703-719]. An important age-associated deficit may be the alteration of the mechanisms controlling Ca2+ handling. Moreover, it has already been proposed that defective fibres in old humans could result from a reduced efficiency of aged satellite cells (a distinct muscle cell subtype, responsible for post-natal growth and repair of damaged fibres) in properly differentiating into myotubes with a mature E-C coupling mechanism [see: Lorenzon et al., Aging affects the differentiation potential of human myoblasts, Exp. Gerontol. 39 (2004) 1545-1554]. Proceeding from these results, the main goal of the present Ph.D. thesis was to investigate whether the inefficiency of aged satellite cells to generate functional skeletal muscle fibres could be partly due to defective voltage-dependent Ca2+ currents. Methods: The whole-cell patch clamp and the videoimaging techniques were employed to measure respectively T- and L-type Ca2+ currents and [Ca2+]i transients in myoblasts and/or myotubes derived from murine and human satellite cells, obtained respectively from young murine skeletal muscle and then aged in vitro under culture conditions, and from human skeletal muscle tissue of healthy donors aged 2, 12, 76 and 86 years. Results: First of all, I confirmed that both murine and human senescent satellite cells fuse more slowly and less efficiently, leading to smaller and thinner myotubes, as known from previous work. Moreover, I showed for the first time that both in myotubes derived from in vitro aged murine satellite cells and in human myotubes derived from satellite cells of old donors the functional expression and the biophysical properties of T- and L-type voltage-dependent Ca2+ channels are impaired. In fact, extensively, less Ca2+ can be available via T-type and L-type channels in old myotubes than in the young ones, and this can be put in relation to the age-related decrease in the quality of myoblast fusion. I also confirmed a specific responsibility of the decrease of the L-type channel number and/or activity for the age-related lowering of intracellular Ca2+ release (the so-called E-C uncoupling; see: Delbono et al., Excitation-calcium release uncoupling in aged single human skeletal muscle fibers, J. Membr. Biol. 148 (1995) 211-222]. Conclusions: From these results one can infer a clear parallelism between the results obtained with the in vitro aging of murine satellite cells model and that concerning the physiological process of human skeletal muscle aging in vivo. In the final analysis, aging effects on voltage-dependent L- and T-type currents could be one of the causes of the inability of old satellite cells to efficiently counteract age-related impairment in muscle force. So, a further strong evidence has been given that in humans, as in other mammals, the satellite cells and the regulation of Ca2+ homeostasis have a decisive role in the physiological process of skeletal muscle aging.
**************************************************************************************** Scopo della ricerca: Nel corso dell’invecchiamento il muscolo scheletrico subisce cambiamenti significativi, quali la perdita di forza e di massa muscolare (sarcopenia; per una rassegna recente vedere: Di Iorio et al., Sarcopenia: age-related skeletal muscle changes from determinants to physical disability, Int. J. Immunopathol. Pharmacol. 19 (2006) 703-719). Era già noto che le disfunzioni correlate all’età potrebbero essere almeno in parte dovute all’inabilità delle cellule satelliti, le cellule staminali per eccellenza del muscolo scheletrico, di rigenerare fibre muscolari funzionali nell’individuo anziano (vedere: Lorenzon et al., Aging affects the differentiation potential of human myoblasts, Exp. Gerontol. 39 (2004) 1545-1554). Il principale scopo di questa Tesi di Dottorato è stato quello di studiare le possibili modificazioni dei meccanismi che regolano l’omeostasi calcica in cellule satelliti murine ed umane, rispettivamente nel corso dell’invecchiamento in vitro (senescenza replicativa in coltura) ed in vivo. In particolare l’attenzione è stata focalizzata sull’effetto delle alterazioni, collegate all’età, delle correnti al Ca2+ voltaggio-dipendenti di tipo L e di tipo T in miotubi provenienti dalla proliferazione e dal differenziamento di cellule satelliti a vari stadi di invecchiamento. Metodologia: Le cellule satelliti murine utilizzate derivavano da una linea primaria espansa denominata i28; le cellule satelliti umane sono state ottenute da biopsie di individui di diversa età (2, 12, 76 e 86 anni). Esperimenti di elettrofisiologia e di videomicroscopia hanno permesso lo studio rispettivamente delle correnti al Ca2+ e dei transienti di Ca2+ intracellulare, nonché delle loro modifiche collegate all’invecchiamento in vitro e in vivo nei modelli murino ed umano. Risultati: Vengono confermati, sia nel modello murino di invecchiamento in vitro che nel modello umano di invecchiamento in vivo, i dati sulla relazione tra sarcopenia e difficoltà di cellule satelliti invecchiate nel formare un numero sufficiente di nuovi miotubi, che anche morfologicamente risultano diversi da quelli derivanti dalla fusione di cellule satelliti giovani. Inoltre, si dimostra per la prima volta che le correnti al Ca2+ in esame sono espresse in minor percentuale e densità, e più tardivamente nel corso del differenziamento, in miotubi derivati da cellule satelliti murine a stadi avanzati di senescenza replicativa, e in cellule umane da donatore anziano. Anche le proprietà biofisiche dei canali di tipo L e T, presenti in miotubi derivati da cellule satelliti invecchiate in vitro e in vivo, appaiono compromesse; complessivamente, meno Ca2+ può entrare attraverso i due tipi di canale e ciò può essere messo in relazione alla riduzione, correlata all’età, della capacità differenziativa e di fusione in miotubi. Viene ulteriormente messo in rilievo il ruolo determinante, nel corso dell’invecchiamento, del calo in numero e in attività dei canali di tipo L, come meccanismo alla base del minor rilascio di calcio intracellulare (fenomeno del disaccoppiamento eccitazione-contrazione; vedere: Delbono et al., Excitation-calcium release uncoupling in aged single human skeletal muscle fibers, J. Membr. Biol. 148 (1995) 211-222). Conclusioni: Dai risultati ottenuti si evince un netto parallelismo tra il modello dell’invecchiamento in vitro di cellule satelliti murine e l’invecchiamento in vivo di cellule satelliti umane. In ultima analisi, si avvalora l’ipotesi che alterazioni età-dipendenti delle correnti al Ca2+ voltaggio-attivate possano essere alla base dell’impossibilità di cellule satelliti invecchiate di contrastare efficacemente la riduzione di forza muscolare caratteristica dell’anziano.
XX Ciclo
1980
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Muth, James N. "CARDIAC-SPECIFIC OVEREXPRESSION OF THE L-TYPE VOLTAGE DEPENDENT CALCIUM CHANNEL IN THE MOUSE." University of Cincinnati / OhioLINK, 2001. http://rave.ohiolink.edu/etdc/view?acc_num=ucin990729124.
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Marshall, Misty. "Brain Cav1 Channel/AKAP15 signaling complexes and the role of the distal C-terminus in Cav1 channel regulation in vivo /." Thesis, Connect to this title online; UW restricted, 2007. http://hdl.handle.net/1773/6297.
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Erickson, Michael G. "Mechanisms of calcium-dependent inactivation of L-type calcium channels revealed by flourescence resonance energy transfer in living cells." Available to US Hopkins community, 2002. http://wwwlib.umi.com/dissertations/dlnow/3080657.
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Perera, Naomi Tessa. "ZnT‐1 expression in the preimplantation mouse embryo and its effect on calcium influx." Thesis, The University of Sydney, 2014. http://hdl.handle.net/2123/13519.
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ZnT-1 expression in the pre-implantation mouse embryo and its effect on calcium influx Pre-implantation embryos develop into 9 stages over the first 5 days post-fertilisation. Calcium influx from the external environment via calcium channels, including the L-type and T-type calcium channels, is critical for embryonic gene activation and cell proliferation. In cardiomyocytes these channels are regulated by the ubiquitously expressed zinc-transporter protein ZnT-1. When plasma membrane bound, ZnT-1 facilitates zinc-efflux. Free cellular zinc regulates ZnT-1 expression, with an increase in zinc inducing transcription. In this study, ZnT-1 mRNA and protein expression were investigated in pre-implantation embryo stages using qPCR and immunofluorescence. Embryos were cultured in vitro in zinc-supplemented media and compared to embryos cultured in the absence of zinc and to in vivo developed embryos. ZnT-1 mRNA was expressed at all stages and the presence of zinc increased mRNA expression a the late 2-cell stage only. There was no difference in expression between in vivo developed and cultured embryos. ZnT-1 protein was expressed from the early 2-cell stage onwards; not affected by zinc culture and localized to the plasma membrane at the late 2-cell stage only. Calcium imaging was performed to examine whether ZnT-1 membrane localization altered calcium influx. Experiments on early and late 2-cell embryos showed that there was no difference in calcium influx when ZnT-1 was localized to the plasma membrane. In summary ZnT-1 transcription was induced by zinc at the late 2-cell stage. Protein expression was not affected by zinc culture but was developmentally regulated, localizing to the plasma-membrane at the late 2-cell stage without effect on calcium influx.
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Jaleel, Naser. "Re-Expression of T-Type Calcium Channels Minimally Affects Cardiac Contractility and Activates Pro-Survival Signaling Pathways in the Myocardium." Diss., Temple University Libraries, 2010. http://cdm16002.contentdm.oclc.org/cdm/ref/collection/p245801coll10/id/83093.
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PhysiologyPh.D.
The role of T-type calcium channels (TTCCs) in the heart is unclear. TTCCs are transiently expressed throughout the neonatal heart during a period of rapid cardiac development. A few weeks postnatally, TTCCs are no longer found in ventricular myocytes (VMs) and calcium influx via TTCCs (ICa,T) is only detected in the SA node and Purkinje system. However, pathologic cardiac stress is associated with re-expression of TTCCs in VMs. Whether ICa,T in this setting promotes cardiac growth or exacerbates cardiac function is a topic of debate. The focus of this thesis work was to examine the effect of TTCC re-expression in the normal and diseased myocardium. Our experiments were performed in a transgenic mouse model with inducible, cardiac-specific expression of α1G TTCCs. While both the α1G and α1H TTCC subtypes re-appear during cardiac disease, we specifically evaluated the effects of α1G TTCCs since mRNA levels of this TTCC subtype are markedly elevated during cardiac pathology. We found that transgenic mice with α1G overexpression had robust ICa,T with biophysical properties similar to those published in previous studies. α1G mice had a small increase in cardiac function and showed no evidence of cardiac histopathology or increased mortality. These findings were in contrast to the phenotype of transgenic mice with augmented L-type calcium channel (LTCC) activity secondary to overexpression of the β2a regulatory subunit. While the magnitude of calcium influx in α1G and β2a VMs was similar, we found that cardiac contractility of β2a mice was significantly greater than α1G mice. Also, β2a mice had significant cardiac fibrosis, myocyte death, and premature lethality compared to the benign phenotype of α1G mice. We showed that the phenotypic differences are likely related to the differential spatial localization of T- and LTCCs. Whereas α1G TTCCs were principally localized to the surface sarcolemma, LTCCs were primarily found in the transverse tubules in close proximity to the sites of sarcoplasmic reticulum calcium release. We evaluated the effect of TTCC expression during cardiac disease by inducing myocardial infarction (MI) in α1G mice. Acutely (1-week post MI), α1G mice showed similar worsening of cardiac function and mortality rates compared to control post-infarct mice. However, α1G hearts had smaller infarct sizes which correlated with increased Akt and NFAT activation in α1G than control hearts. After chronic heart failure, i.e. 7- weeks post-infarction, α1G hearts had significant hypertrophic response as determined by increased HW/BW ratio, myocyte cross-sectional area, as well as NFAT and Akt activity. Finally, α1G mice had a small survival benefit than control mice, which while statistically non-significant, suggests that TTCC re-expression does not exacerbate cardiac function as hypothesized by some investigators. We conclude that TTCCs play a minimal role in cardiac function and activate pro-survival signaling pathways in the myocardium.
Temple University--Theses
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Baumann, Ludwig. "Structural and functional analysis of the Cav1.4 L-type calcium channel from mouse retina." Diss., [S.l.] : [s.n.], 2006. http://edoc.ub.uni-muenchen.de/archive/00005321.
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Lalonde, Megan Mireille. "The modulation of L-type calcium channel currents by PTHrP in osteoblast-like cells." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1997. http://www.collectionscanada.ca/obj/s4/f2/dsk3/ftp05/mq22623.pdf.
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Ruppell, Kendra Takle. "Neural Bursting Activity Mediates Subtype-Specific Neural Regeneration by an L-type Calcium Channel." eScholarship@UMMS, 2019. https://escholarship.umassmed.edu/gsbs_diss/1032.
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Axons are injured after stroke, spinal cord injury, or neurodegenerative disease such as ALS. Most axons do not regenerate. A recent report suggests that not all neurons are poor regenerators, but rather a small subset can regenerate robustly. What intrinsic property of these regenerating neurons allows them to regenerate, but not their neighbors, remains a mystery. This subtype-specific regeneration has also been observed in Drosophila larvae sensory neurons. We exploited this powerful genetic system to unravel the intrinsic mechanism of subtype-specific neuron regeneration. We found that neuron bursting activity after axotomy correlates with regeneration ability. Furthermore, neuron bursting activity is necessary for regeneration of a regenerative neuron subtype, and sufficient for regeneration of a non-regenerative neuron subtype. This optogenetically-induced regeneration is dependent on a bursting pattern, not simply overall activity increase. We conclude that neuron bursting activity is an intrinsic mechanism of subtype-specific regeneration. We then discovered through a reverse genetic screen that an L-type voltage gated calcium channel (VGCC) promotes neuron bursting and subsequent regeneration. This VGCC has high expression in the regenerative neuron and weak expression in the non-regenerative neuron. This suggests that VGCC expression level is the molecular mechanism of subtype-specific neuron regeneration. Together, our findings identify a cellular and molecular intrinsic mechanism of subtype-specific regeneration, which is why some neurons are able to regenerate while the majority of neurons do not. Perhaps VGCC activation or neuron activity pattern modulation could be used therapeutically for patients with nerve injury.
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Ugenti, Maria Paola <1977>. "Characterization of L-type Calcium Channel Binding-Site of a new class of Calcium modulators by a Multidisciplinary approach." Doctoral thesis, Alma Mater Studiorum - Università di Bologna, 2009. http://amsdottorato.unibo.it/1277/1/Ugenti_MariaPaola_tesi.pdf.
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Many potential diltiazem related L-VDCC blockers were developed using a multidisciplinary approach. This current study was to investigate and compare diltiazem with to the newly developed compounds by mouse Langendorff-perfused heart, Ca2+-transient and on recombinant L-VDCC. Twenty particular compounds were selected by the ligand-based virtual screening procedure (LBVS). From these compounds, five of them (5b, M2, M7, M8 and P1) showed a potent and selective inotropic activity on guinea-pig left atria driven 1 Hz. Further assays displayed an interesting negative inotropic effect of M2, M8, P1 and M7 on guinea pig isolated left papillary muscle driven at 1 Hz, a relevant vasorelaxant activity of 5b, M2, M7, M8 and P1 on K+-depolarized guinea-pig ileum longitudinal smooth muscle and a significant inhibition of contraction of 5b, M2, M8 and P1 on carbachol stimulated ileum longitudinal smooth muscle.
Wild-type human heart and rabbit lung α1 subunits were expressed (combined with the regulatory α2δ and β3 subunits) in Xenopus Leavis oocytes using a two-electrode voltage clamp technique. Diltiazem is a benzothiazepine Ca2+ channel blocker used clinically for its antihypertensive and antiarrhythmic effects. Previous radioligand binding assays revealed a complex interaction with the benzothiazepine binding site for M2, M7 and M8. (Carosati E. et al. J. Med Chem. 2006, 49; 5206). In agreement with this findings, the relative order of increased rates of contraction and relaxation at lower concentrations s(≤10-6M) in unpaced hearts was M7>M2>M8>P1. Similar increases in Ca2+ transient were observed in cardiomyocytes. Diltiazem showed negative inotropic effects whereas 5b had no significant effect. Diltiazem blocks Ca2+current in a use-dependent manner and facilitates the channel by accelerating the inactivation and decelerating the recovery from inactivation. In contrast to diltiazem, the new analogs had no pronounced use-dependence. Application of 100 μM M8, M2 showed ~ 10% tonic block; in addition, M8, M2 and P1 shifted the steady state inactivation in hyperpolarized direction and the current inactivation time was significantly decreased compared with control (219.6 ± 11.5 ms, 226 ± 14.5 vs. 269 ± 12.9 vs. 199.28 ± 8.19 ms). Contrary to diltiazem, the recovery from the block by M8 and M2 was comparable to control. Only P1 showed a significantly decrease of the time for the recovery from inactivation. All of the compounds displayed the same sensitivity on the Ca2+ channel rabbit lung α1 except P1. Taken together, these findings suggest that M8, M2 and P1 might directly decrease the binding affinity or allow rapid dissociation from the benzothiazepine binding site.
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Ugenti, Maria Paola <1977>. "Characterization of L-type Calcium Channel Binding-Site of a new class of Calcium modulators by a Multidisciplinary approach." Doctoral thesis, Alma Mater Studiorum - Università di Bologna, 2009. http://amsdottorato.unibo.it/1277/.
Full textAbstract:
Many potential diltiazem related L-VDCC blockers were developed using a multidisciplinary approach. This current study was to investigate and compare diltiazem with to the newly developed compounds by mouse Langendorff-perfused heart, Ca2+-transient and on recombinant L-VDCC. Twenty particular compounds were selected by the ligand-based virtual screening procedure (LBVS). From these compounds, five of them (5b, M2, M7, M8 and P1) showed a potent and selective inotropic activity on guinea-pig left atria driven 1 Hz. Further assays displayed an interesting negative inotropic effect of M2, M8, P1 and M7 on guinea pig isolated left papillary muscle driven at 1 Hz, a relevant vasorelaxant activity of 5b, M2, M7, M8 and P1 on K+-depolarized guinea-pig ileum longitudinal smooth muscle and a significant inhibition of contraction of 5b, M2, M8 and P1 on carbachol stimulated ileum longitudinal smooth muscle.
Wild-type human heart and rabbit lung α1 subunits were expressed (combined with the regulatory α2δ and β3 subunits) in Xenopus Leavis oocytes using a two-electrode voltage clamp technique. Diltiazem is a benzothiazepine Ca2+ channel blocker used clinically for its antihypertensive and antiarrhythmic effects. Previous radioligand binding assays revealed a complex interaction with the benzothiazepine binding site for M2, M7 and M8. (Carosati E. et al. J. Med Chem. 2006, 49; 5206). In agreement with this findings, the relative order of increased rates of contraction and relaxation at lower concentrations s(≤10-6M) in unpaced hearts was M7>M2>M8>P1. Similar increases in Ca2+ transient were observed in cardiomyocytes. Diltiazem showed negative inotropic effects whereas 5b had no significant effect. Diltiazem blocks Ca2+current in a use-dependent manner and facilitates the channel by accelerating the inactivation and decelerating the recovery from inactivation. In contrast to diltiazem, the new analogs had no pronounced use-dependence. Application of 100 μM M8, M2 showed ~ 10% tonic block; in addition, M8, M2 and P1 shifted the steady state inactivation in hyperpolarized direction and the current inactivation time was significantly decreased compared with control (219.6 ± 11.5 ms, 226 ± 14.5 vs. 269 ± 12.9 vs. 199.28 ± 8.19 ms). Contrary to diltiazem, the recovery from the block by M8 and M2 was comparable to control. Only P1 showed a significantly decrease of the time for the recovery from inactivation. All of the compounds displayed the same sensitivity on the Ca2+ channel rabbit lung α1 except P1. Taken together, these findings suggest that M8, M2 and P1 might directly decrease the binding affinity or allow rapid dissociation from the benzothiazepine binding site.
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Liu, Yudan. "Dopaminergic neurons in the ventral tegmental area: role of L-type calcium channels in firing regulation /." Internet access available to MUN users only. Search for this title in:, 2009.
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Angelini, M. "ROLE OF CLIC1 AND L-TYPE CALCIUM CHANNELS IN THE PATHOPHYSIOLOGY OF GLIOBLASTOMA AND VENTRICULAR ARRHYTHMIAS." Doctoral thesis, Università degli Studi di Milano, 2015. http://hdl.handle.net/2434/268235.
Full textAbstract:
Ion channels are transmembrane proteins that allow and control the flux of ions (sodium, potassium, calcium, and chloride) across the plasma membrane. They are present in all cell types and play critical roles in a variety of biological processes. Historically, ion channels have always been an attractive target for the treatment of different pathologies mainly because numerous drugs can specifically bind ion channels modifying their functional activity. My PhD thesis addresses the role of two different ion channels in the two leading causes of death in the modern society: heart disease and cancer. The first part of this PhD dissertation, developed at University of Milan under the mentorship of Prof. Michele Mazzanti, focuses on understanding the role of CLIC1 channels in glioblastoma cancer stem cells (CSCs). Glioblastoma is the most lethal among brain tumors. As other solid tumors, this cancer is composed of two cell types: a small population of cells able to self-renew and generate progeny (CSCs) and a larger population of differentiated cells (bulk cells). Glioblastomas are very aggressive tumors because of CSCs brain infiltration efficiency and resistance to chemotherapies. CLIC1 is a metamorphic protein mainly present as a soluble form in the cytoplasm that is able to translocate to the plasma membrane in response to oxidative stimuli where it acts as a Cl- channel. Several forms of glioblastomas show a high level of expression of CLIC1 compared to normal brains tissue. In electrophysiological experiments, overexpression of CLIC1 in murine CSCs were associated with a specific increase of the protein at the plasma membrane compared to normal stem cell (NSC). To study the relevance of CLIC1 we used CSCs isolated from human glioblastoma biopsies. By knocking down CLIC1 protein using siRNA viral infection (siCLIC1), we found that CLIC1-deficient cells proliferate less efficiently than control cells infected with siRNA for luciferase (siLUC). Since CLIC1 is a dimorphic protein we asked whether the reduction in proliferation was due to CLIC1 as ion channel. We performed perforated patches electrophysiological experiments for both siLUC and siCLIC1 cells. Cl- currents mediated by CLIC1 were isolated using IAA94, a CLIC1 ion channel inhibitor. The results showed that siCLIC1 cells did not display IAA94-sensitive currents, while siLUC cells presented the CLIC1-mediated chloride current. These findings strongly suggest that CLIC1 ion channel activity is required in the proliferation activity of CSCs, and therefore represents a promising target direct in the reduction of CSC gliomagenesis. To target CLIC1 ion channel, the only effective drug so far identified is IAA94 which seems to be rather specific but toxic. For this reason we sought non-toxic drugs that could interact with CLIC1 ion channel. Epidemiological and preclinical studies propose that Metformin, a first-line drug for type-2 diabetes, exerts direct antitumor activity specifically on CSCs. Although several clinical trials are ongoing, the molecular mechanisms of this effect are unknown. To study Metformin's effect on CLIC1-mediated current (isolated with IAA94), we performed electrophysiological experiments from perforated patches using a glioblastoma U87 cell line. We constructed a dose response curve comparing Metformin effect on CLIC1 maximum current (isolated using IAA94) from which we calculated EC50 2.1 ± 0.4 mM. To validate the specificity of Metformin for CLIC1, we compared the extent of block of this drug to the one of IAA94 by sequentially adding the two inhibitors with either order. If the second drug perfusion did not show additional block, we can confirm that the two inhibitor share the same target. Interestingly, experimental data show that Metformin-mediated inhibition of CLIC1 is similar to IAA94 block, suggesting that they both act on CLIC1. Metformin displays antiproliferative activity mainly acting on CSC and not on the differentiated cells. Is this phenotype the result of different expression of CLIC1 in plasma membranes? Interestingly, the relative abundance of CLIC1-mediated current in CSCs was about three fold bigger than in differentiated cells, suggesting that CLIC1 inhibition is relevant in the antiproliferative activity of Metformin. We sought to understand how Metformin bind the channel. Taking advantage of computational modeling and the available CLIC1 crystal structure, our collaborator predicted that the arginin 29 (R29) in the CLIC1 transmembrane domain may be part of the Metfomin binding site. We test this hypothesis in perforated patch clamp experiment using CHO cells stably transfected with CLIC1 wild type or CLIC1 R29A. The substitution of Arg29 in the putative CLIC1 pore region impairs Metformin modulation of channel activity. These results demonstrate that CLIC1 is required for human glioblastoma cell proliferation. Furthermore, we identified CLIC1 as direct target of Metformin antiproliferative activity in human glioblastoma cells. These findings are paving the way for novel and needed pharmacological approaches to glioblastoma treatment. The second part of this PhD dissertation, focusing on cardiac arrhythmia, was developed at University of California, Los Angeles under the mentorship of Prof. Riccardo Olcese. The electrical activity of the heart originates from the rhythmic activity in the sinoatrial node (SAN) and spreads across the heart as a wave of depolarization (the cardiac action potential). While the normal ventricular cardiac action potential (AP) repolarizes monotonically, returning to the diastolic membrane potential, under certain pathological conditions the repolarization can be interrupted by sudden depolarizations called early afterdepolarizations (EADs), occurring during phase 2 or phase 3 of the AP. These events, observable at the cellular and tissue level, are recognized triggers of cardiac arrhythmias. In fact, EADs can generate a new AP that propagates across the heart disrupting the propagation of normal AP wave leading to ventricular tachycardia (VT) and ventricular fibrillation (VF). Ventricular fibrillation is the most commonly identified arrhythmia in sudden cardiac death (SCD), one of the leading causes of death in the United States. This project investigated the relevance of the voltage gated L-type calcium channel (CaV1.2) in the etiology of EADs of the cardiac action potential. EADs are largely induced by the reactivation of L-type Ca2+ currents (ICa,L) that occurs at the range of membrane potential from -40 to 0 mV, called window current region. To study the dependence of EADs on the biophysical properties of L-type Ca2+ current (ICa,L) we adopted a hybrid biological–computational approach: the dynamic clamp technique. Under dynamic clamp it was possible to replace the native ICa,L of a ventricular myocyte with a computed ICa,L defined by programmable parameters. We previously identified three L-type Ca2+ channel (LTCC) biophysical parameters that effectively suppress EADs induced by oxidative stress or hypokalemia by preventing ICa,L reactivation in the window current region. Specifically, EADs were potently suppressed by: i) a ~5 mV depolarizing shift of the steady-state activation curve, ii) a ~5 mV hyperpolarizing shift of the steady-state inactivation curve or iii) a reduction of the non-inactivating pedestal component. Importantly, these changes did not significantly alter the peak ICa,L or Ca2+ transient amplitude during the action potential. Since LTCCs are multiprotein complexes in which CaVβ subunits modulate the gating properties and voltage dependence of the pore-forming CaV1.2 α1C subunit, we explored whether modifying LTCC β subunit composition is a suitable therapeutic strategy to suppress EADs. Voltage clamp experiments, in which we expressed Cav1.2 α1c with different β subunits, showed that subunit subtypes β2a and β2b, which are abundantly expressed in ventricular myocytes, give rise to LTCCs with voltage-dependent properties favoring EADs formation. Accordingly, we tested an adenovirus-based shRNA delivery strategy to reduce β2 expression in primary ventricular myocyte cultures; the rationale being that a LTCC population in a cell with a smaller proportion of β2a- and β2b-containing channels should generate ICa,L with an overall voltage dependence disfavorable to EADs emergence. The simultaneous partial knock down of β2a and β2b shifted the whole-cell ICa,L steady-state activation curve to more depolarized potentials by ~4 mV without significantly affecting peak ICa,L. A “narrower” window current could diminish the probability of EADs formation by preventing channel reopening. In congruence with the dynamic clamp results, EADs occurrence under oxidative stress (H2O2) was potently prevented in rabbit ventricular myocytes with β2 knock-down (no EADs observed). Conversely, control myocytes from the same batches exhibited significant action potential prolongation and all cells developed EADs after H2O2 exposure. These findings demonstrate that manipulation of the subunit composition can be an effective strategy for modifying the steady-state properties of ICa,L. Thus, our results highlight the use of genetic engineering as a therapeutic avenue for the treatment of EADs-related cardiac arrhythmias.
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Guan, Yinzheng. "Blebbistatin Protects Rodent Myocytes from Death in Primary Culture via Inhibiting the Sodium/ Calcium Exchanger and the L-type Calcium Channel." Master's thesis, Temple University Libraries, 2011. http://cdm16002.contentdm.oclc.org/cdm/ref/collection/p245801coll10/id/150014.
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PhysiologyM.S.
Introduction: Cardiac disease is a leading cause of mortabity and morbidity in the developed countries. Cultured cardiac myocytes are widely used for exploring the underlying pathophysiology of cardiac disease. Rodents, especially mice with transgenes or gene ablation, have become popular animal models for heart disease research. However, it has been long recognized that rodent myoyctes die during long-term primary culture, which limits the use of genetically altered myocytes for signaling studies. Blebbistatin (BLB), a myosin II ATPase inhibitor, has been used to protect rodent myocytes. The mechanisms underlying the protective effects of this drug are not clear and are the topics of this study. Materials & methods: Adult rat ventricular myocytes (ARVM) were isolated and cultured with or without BLB (10 µM) for 72 hours in comparison with another protective chemical, BDM (10mM). Myocyte death was evaluated by morphology changes and trypan blue staining. The effects of these two drugs on myocyte contraction, intracellular Ca2+ transient ([Ca2+]i, indo-1,410/480), SR Ca2+ content, L-type calcium and Na+ /Ca2+exchanger currents were studied acutely. Neonatal rat ventricular myocytes (NRVM) were isolated from 1-3 days old neonatal rat hearts and cultured. The effect of BDM (10mM BDM) and BLB (10 µM) in the medium on NRVM growth and hypertrophy induced by norepinephrine (NE, 10µM) were determined. Results: 1. Both BDM and BLB promoted myocyte survival in culture at 72 hours but BLB protected more myocytes (Control: 7.0±1.8% vs. BDM: 61.5±6.4% vs. BLB: 74.0±3.2%); 2. ARVM fractional shortening was reduced by BLB to 1.7±0.4% and by BDM to 0.5±0.1% from the baseline of 6.5±0.7%; 3. Acutely, the amplitude of [Ca2+]i (∆ [Ca2+]i) evaluated with indo-1 AM (F410/F480) was depressed by both BDM (0.04±0.01) and BLB (0.07±0.01) compared to control (0.13±0.01). 4. Diastolic Ca2+ was significantly increased by BLB (0.90±0.06) but not by BDM (0.73±0.06) compared to pre-treat values (0.70±0.05); 5. BLB and BDM significantly reduced the SR Ca2+ content, as indicated by the reduced amplitudes of caffeine-induced Ca2+ transients in BLB- and BDM-treated ARVMs (∆[Ca2+]i in BLB vs. BDM vs. baseline: 0.20±0.03, 0.19±0.04, 0.30±0.03). 6. The mechanisms of the protective effects of BDM and BLB were similar but quantitatively different in that BDM reduced more Ca influx through the L-type Ca2+ channel (ICa-L) than BLB (the reduction in BDM-treated cells vs. BLB-treated cells: 70% vs. 40%) while BLB inhibited more Na+/Ca2+exchanger current (75% inhibition) than BDM (40% reduction); 7. Both BDM and BLB inhibited normal NRVM growth and NE-induced hypertrophy and NFAT translocation in NRVMs. Conclusion: These results suggest both BDM and BLB protect rodent myocytes in culture by preventing cytosolic and SR Ca2+ overload by similar mechanisms: inhibiting NCX and reducing the LTCC. The application of BLB to whole-heart studies and myocyte hypertrophy should be extremely cautioned because BLB does alter myocyte Ca2+ handling.
Temple University--Theses
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Sykes, Lucy Helen. "The role of L-type voltage gated calcium channels and psychiatric risk gene CACNA1C in associative learning." Thesis, Cardiff University, 2016. http://orca.cf.ac.uk/98747/.
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CACNA1C codes for the alpha-1 subunit of Cav1.2 L-type voltage gated calcium channels (LVGCCs). Variation in CACNA1C has been reliably implicated in psychiatric illness, including schizophrenia and bipolar disorder. Analyses have indicated a convergence of genetic risk for schizophrenia on abnormalities in the synapse and in behaviours including associative learning. LVGCCs play a role in synaptic plasticity and learning, partly through regulation of gene transcription. Their role in specific aspects of associative learning that are relevant for symptoms of psychiatric illness is yet to be fully elucidated. A hippocampal-dependent fear conditioning paradigm was used to determine the role of Cacna1c and LVGCCs in specific aspects of associative learning in rats. Studies measured the activity-regulated expression of Cacna1c and the effect of inhibition of LVGCCs. A genetic Cacna1c knockdown rat model was used to investigate the effects of reduced expression on behaviour and the expression of brain derived neurotrophic factor (BDNF). This model was additionally tested on reward-based reversal-learning. Analyses were translated to humans, to assess whether disease relevant variation in CACNA1C was associated with similar deficits in reversal learning and expression. Inhibition of LVGCCs affected the consolidation, extinction and latent inhibition of contextual fear memory, whereas reduced expression of Cacan1c had a selective effect on latent inhibition. There were no effects on the acquisition of reward associations, but reversal learning was impaired. Similar deficits in reversal learning were associated with disease relevant variation in CACNA1C in humans. Reduced CACNA1C expression was found to be associated with changes in the expression of BDNF in both rats and humans. Results indicate a role for Cacna1c and LVGCCs in the appropriate formation and update of aversive and reward associations. Impairments in these processes can underlie specific symptoms of disease including emotion dysregulation and delusions. The cross-species effects on BDNF require further investigation.
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RUSCONI, FRANCESCA. "THE IMPORTANT ROLE OF AKT IN THE MODULATION OF HEART INOTROPISM THROUGH L-TYPE CALCIUM CHANNELS FUNCTION." Doctoral thesis, Università degli Studi di Milano, 2010. http://hdl.handle.net/2434/150100.
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The insulin IGF1/Akt signaling pathway has recently been shown to be critical for the regulation of heart function and physiology. Indeed, compelling evidence shows activation of this pathway as one of the most important determinants for the enhancement of cardiac function and physiological growth in athletes, whereas its impairment is considered critical for the development of heart failure (HF). In this doctoral thesis, our aim was to determine the functional role of known and novel key-factors of this pathway to study whether their modulation might be envisaged as therapeutic tool for curing pathological cardiac hypertrophy (CH) and HF.
Physiological CH is an adaptive response of the heart to stimuli, such as developmental growth and training and differs markedly from pathological hypertrophy occurring in patients with HF. In this thesis, we demonstrated the involvement of Akt kinase in regulating heart inotropism by modulating L-Type Ca2+ Channel (LTCC) density and function. In a mouse model with inducible and cardiac specific deletion of PDK1, the upstream activator of Akt, we found that the protein stability of the LTCC pore subunit (Cavα1) can be modulated by the kinase. In particular, phosphorylation of the C-terminal coiled coil of the Cavβ2 chaperone subunit enhances LTCC protein stability by prevention of PEST-mediated Cavα1 degradation. Subsequently, to determine whether the modulation of this mechanism may be used for the treatment of HF, we studied the fine-regulation of LTCC density and activity by investigating the functional role of Akt-phosphomimetics Cavβ2 constructs. Three Akt-phosphomimetic sequences corresponding to the Cavβ2 C-terminal coiled coil were identified and shown to protect Cavα1 from protein degradation, through an increase in the number of functional LTCC. Moreover, to establish whether the Akt-dependent phosphorylation of CaVβ2 might be a trigger for the recruitment of other protein interacting partners, yeast two-hybrid screenings of human and mouse heart cDNA expression libraries revealed a fold-back interaction of the Akt-phosphorylated-Cavβ2 tail with a region of the Cavβ2 globular domain. Co-immunoprecipitation experiments confirmed this interaction, while negative results were obtained when Cavβ2-WT was used as bait. This provided the proof of concept for a mechanism of action that relies on Akt-dependent phosphorylation. Site-specific mutagenesis in the identified interacting domain confirmed this mechanism. All togheter, we found that the Akt-dependent protective effect on Cavα1 stability might relay on Cavβ2 structural rearrangements, which follow the phosphorylated C-terminal coiled coil fold back on its globular domain.
In conclusion, results from this doctoral thesis provide further insights into the role of the insulin IGF1/Akt signaling pathway and its role in the modulation of myocardial physiology and HF. These findings may lead to the development of new therapeutical tools that will be useful for the modulation of impaired cardiac contractility in HF.
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Köth, Jessica [Verfasser]. "Cardiac L‐type calcium channels and expression of RGK proteins in mouse models associated with type 2 diabetes / Jessica Köth." Bonn : Universitäts- und Landesbibliothek Bonn, 2017. http://d-nb.info/1170778097/34.
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Böhnke, Ann-Kristin [Verfasser]. "Structural remodeling of L-type calcium channel subunits in human and murine atherosclerosis / Ann Kristin Böhnke." Bonn : Universitäts- und Landesbibliothek Bonn, 2012. http://d-nb.info/1047622653/34.
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Oliveria, Seth F. "Localized calcineurin controls L-type Ca²⁺ channel activity and nuclear signaling /." Connect to abstract via ProQuest. Full text is not available online, 2008.
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Thesis (Ph.D. in Neuroscience) -- University of Colorado Denver, 2008.Typescript. Includes bibliographical references (leaves 110-125). Online version available via ProQuest Digital Dissertations.
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Rey, Stéphanie. "Physiological involvement of presynaptic L-type voltage dependent calcium channels in GABA release of cerebellar molecular layer interneurons." Thesis, Paris 5, 2013. http://www.theses.fr/2013PA05T096/document.
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La libération de neurotransmetteur est provoquée par la dépolarisation de la terminaison présynaptique et l’entrée de calcium à travers les canaux calciques voltagedépendants (VDCCs). Les VDCCs à haut seuil de type-P/Q et de type-N sont classiquement impliqués dans la libération de neurotransmetteurs et sont localisés dans la terminaison axonale près de la zone active. Deux membres de la famille des VDCCs de type-L, Cav1.2 et Cav1.3 sont connus pour être exprimés dans le système nerveux central. Dans le cortex cérébelleux, les propriétés pharmacologiques des VDCCs présynaptiques ont été examinées aux synapses GABAergiques entre les interneurones de la couche moléculaire (MLIs) et entre les MLIs et les cellules de Purkinje. Bien qu’il n’y ait aucun doute que les VDCCs de type- P/Q et de type-N sont les principaux acteurs de l’entrée de calcium présynaptique et de la libération de GABA par les MLIs, l’absence d’effet des dihydropyrines antagonistes a exclut le potentiel rôle des VDCCs de type-L (Forti et al., 2000; Stephens et al., 2001). Il est intéressant de noter que les dihydropyrines antagonistes sont très peu efficaces sur les courants calciques de type-L activés par un potentiel d’action (Helton et al., 2005), ce qui suggère que l’implication des VDCCs de type-L dans la libération de neurotransmetteur a été largement négligée. Dans cette étude, nous avons montré que le BayK8644 (une dihydropyridine agoniste) augmente fortement la fréquence des mIPSCs enregistrés dans les MLIs et dans les cellules de Purkinje suggérant que les VDCCs de type-L peuvent être présents dans les terminaisons axonales des MLIs. Ce résultat a été confirmé par des expériences d’immunohistochimie utilisant la microscopie confocale et électronique ainsi que par des expériences d’imagerie calcique. Nos résultats démontrent que les VDCCs de type-L, souvent négligés dans les terminaisons axonales, ont un rôle crucial dans la libération de GABA par les MLIsPhysiological involvement of presynaptic L-type voltage dependent calcium channels in GABA release of cerebellar molecular layer interneurons
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Udagawa, Rie. "Blocking L-type calcium channels enhances long-term depression induced by low-frequency stimulation at hippocampal CA1 synapses." Kyoto University, 2008. http://hdl.handle.net/2433/135930.
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Dizayee, Sara [Verfasser]. "Cardiac Gαi2 Protein Function and Regulation of High-Voltage-Gated L-type Calcium Channels / Sara Dizayee." Bonn : Universitäts- und Landesbibliothek Bonn, 2012. http://d-nb.info/1043911022/34.
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Wright, David C. "The role of PLC, cPKC, L-type calcium channels and CAMKII in insulin stimulated glucose transport in skeletal muscle." Virtual Press, 2002. http://liblink.bsu.edu/uhtbin/catkey/1233206.
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Li, Wen. "A Quantitative Manganese-Enhanced MRI Method For In Vivo Assessment Of L-Type Calcium Channel Activity In Heart." Case Western Reserve University School of Graduate Studies / OhioLINK, 2011. http://rave.ohiolink.edu/etdc/view?acc_num=case1300810473.
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Young, Lois-May. "Evaluation of polycyclic amines as modulators of calcium homeostasis in models of neurodegeneration / Young L." Thesis, North-West University, 2012. http://hdl.handle.net/10394/7591.
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Compromised calcium homeostasis in the central nervous system (CNS) is implicated as a major contributor in the pathology of neurodegeneration. Dysregulation of Ca2+ homeostasis initiates downstream Ca2+–dependent events that lead to apoptotic and/or necrotic cell death. Increases in the intracellular free calcium concentration ([Ca2+]i) may be the result of Ca2+ influx from the extracellular environment or Ca2+ release from intracellular Ca2+ stores such as the endoplasmic reticulum (ER). Influx from the extracellular environment is controlled predominantly by voltage gated calcium channels (VGCC), such as L–type calcium channels (LTCC) and ionotropic glutamate receptors, such as the N–methyl–D–aspartate (NMDA) receptors. Ca2+ release from the ER occurs through the inositol–1,4,5–triphosphate receptors (IP3Rs) or ryanodine receptors (RyRs) via IP3–induced or Ca2+–induced mechanisms. Mitigation of Ca2+ overload through these Ca2+ channels offers an opportunity for pharmacological interventions that may protect against neuronal death.
In the present study the ability of a novel series of polycyclic compounds, both the pentacycloundecylamines and triquinylamines, to regulate calcium influx through LTCC was evaluated in PC12 cells using calcium imaging with Fura–2/AM in a fluorescence microplate reader. We were also able for the first time to determine IC50 values for these compounds as LTCC blockers. In addition, selected compounds were evaluated for their ability to offer protection in apoptosis–identifying assays such as the lactate dehydrogenase release assay (LDH–assay), trypan blue staining assay and immunohistochemistry utilizing the Annexin V–FITC stain for apoptosis. We were also able to obtain single crystal structures for the tricyclo[6.3.0.02,6]undecane–4,9–dien–3,11–dione (9) and tricyclo[6.3.0.02,6]undecane–3,11–dione (10) scaffolds as well as a derivative, N–(3–methoxybenzyl)–3,11–azatricyclo[6.3.0.02,6]undecane (14f). We also evaluated the possibility that the polycyclic compounds might be able to modulate Ca2+ flux through intracellular Ca2+ channels.
Computational methods were utilized to accurately predicted IC50 values and develop a QSAR model with marginal error. The linear regression model delivered r2 = 0.83, which indicated a favorable correlation between the predicted and experimental IC50 values. This model could thus serve as valuable predictor for future structural design and optimization efforts. Data obtained from the crystallographic analysis confirmed the NMR–data based structural assignments done for these compounds in previous studies. Obtaining structural information gave valuable insight into the differences in size and geometric constrains, which are key features for the LTCC activity of these compounds.
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In conclusion, we found that all of the compounds evaluated were able to attenuate Ca2+ influx through the LTCC, with some compounds having IC50 values comparable with known LTCC blockers such as nimodipine. Representative compounds were evaluated for their ability to afford protection against apoptosis induced by 200 ?M H2O2. With the exception of compound 14c (the most potent LTCC blocker in the series, IC50 = 0.398 ?M), most compounds were able to afford protection at two or more concentrations evaluated. Compound 14c displayed inherent toxicity at the highest concentrations evaluated (100 ?M). We concluded that compounds representing both types of structures (pentacycloudecylamines and triquinylamines) have the ability to attenuate excessive Ca2+ influx through the LTCC. In general the aza–pentacycloundecylamines (8a–c) were the most potent LTCC blocker which also had the ability to offer protection in the cell viability assays. However, NGP1–01 (7a) had the most favorable pharmacological profile overall with good activity as an LTCC blocker (IC50 = 86 ?M) and the ability to significantly attenuate cell death in the cell viability assays, exhibiting no toxicity. In addition to their ability to modulate Ca2+ influx from the extracellular environment, these compounds also displayed the ability to modulate Ca2+ flux through intracellular Ca2+ channels. The mechanisms by which they act on intracellular Ca2+ channels still remains unclear, but from this preliminary study it would appear that these compounds are able to partially inhibiting Ca2+–ATPase activity whilst possibly simultaneously inhibiting the IP3R. In the absence of extracellular Ca2+ these compounds showed the ability in inhibit voltage–induced Ca2+ release (VICaR), possibly by modulating the gating charge of the voltage sensor being the dihydropyridine receptors.
In future studies it might be worthwhile to do an expanded QSAR study and evaluate the aza–pentacycloundecylamines. To clarify the mechanisms by which the polycyclic compounds interact with intracellular Ca2+ channels we should examine the direct interaction with the individual Ca2+ channels independently. The polycyclic compounds evaluated in this study demonstrate potential as multifunctional drugs due to their ability to broadly regulate calcium homeostasis through multiple pathways of Ca2+ entry. This may prove to be more effective in diseases where perturbed Ca2+ homeostasis have devastating effects eventually leading to excitotoxicity and cell death.Thesis (Ph.D. (Pharmaceutical Chemistry))--North-West University, Potchefstroom Campus, 2012.
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[Verfasser], Montatip Poomvanicha, Franz [Akademischer Betreuer] Hofmann, and Michael [Akademischer Betreuer] Schemann. "Modulation of cardiac L-type calcium channels by genetic modification / Montatip Poomvanicha. Gutachter: Michael Schemann ; Franz Hofmann. Betreuer: Franz Hofmann." München : Universitätsbibliothek der TU München, 2014. http://d-nb.info/1060193833/34.
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Pickel, Simone [Verfasser], Michaela [Gutachter] Kuhn, and Sören [Gutachter] Doose. "Role of the β subunit of L-type calcium channels in cardiac hypertrophy / Simone Pickel ; Gutachter: Michaela Kuhn, Sören Doose." Würzburg : Universität Würzburg, 2020. http://d-nb.info/1223851214/34.
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Guzman, Kathleen Marie. "EFFECTS OF CALCIUM CHANGES ON HYSTERESIS IN RESTITUTION OF ACTION POTENTIAL DURATION." UKnowledge, 2009. http://uknowledge.uky.edu/gradschool_theses/604.
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Sudden cardiac death (SCD) is a leading cause of fatalities. Several methods have been developed to predict instability in myocytes which could lead to SCD. The focus of this study was on altering memory in myocytes, i.e. hysteresis in restitution of action potential duration (APD), by differing levels of calcium. Determination of alteration was implemented by using a diastolic interval (DI) control program that implements a sinusoidal change in DI. Plotting APD versus previous DI, i.e. restitution, produces a hysteresis loop. From these hysteresis loops, five parameters were used to determine measures of memory: area, thickness, overall tilt, max delay and min delay. Calcium levels were then altered with either verapamil or BAPTA-AM. Statistically significant effects were found for the verapamil study, but not for the BAPTA-AM study. Simulations were used to explain significant results. The verapamil findings support clinical studies that have shown verapamil to not have anti-arrhythmic effects. Theory predicts that a decrease in memory would decrease the stability of a system, and perhaps verapamil may not increase stability as hypothesized previously. The results of the BAPTA-AM study were inconclusive, and further investigation is needed before it can be determined that BAPTA-AM has no significant effect on memory.
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Ramos-Filho, Antonio Celso Saragossa 1985. "Participação do receptor de potencial transiente vanilóide do tipo 4 (TRPV4) e do melastatina do tipo 8 (TRPM8) nas disfunções miccionais do diabetes em camundongos." [s.n.], 2014. http://repositorio.unicamp.br/jspui/handle/REPOSIP/312586.
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Orientador: Edson AntunesTese (doutorado) - Universidade Estadual de Campinas, Faculdade de Ciências Médicas
Made available in DSpace on 2018-08-25T08:00:03Z (GMT). No. of bitstreams: 1 Ramos-Filho_AntonioCelsoSaragossa_D.pdf: 3024613 bytes, checksum: a03a80c65d863acd441249f461461216 (MD5) Previous issue date: 2014
Resumo: Os receptores TRPV4 e TRPM8 são expressos no urotélio e em fibras aferentes sensitivas da bexiga. Fisiologicamente, a ativação mecânica do receptor TRPV4 na parede da bexiga participa do controle miccional. Em doenças de origem inflamatória, esses receptores adquirem funcionalidade importante. As disfunções da bexiga no diabetes podem estar associadas a alterações ao nível de detrusor, inervação e urotélio. A disfunção urotelial parece ser a responsável por desencadear as alterações neurais e musculares da bexiga. Assim, o objetivo do presente estudo foi investigar os mecanismos fisiopatológicos da ativação dos receptores TRPV4 e TRPM8 no estado diabético em camundongos. Para tanto, dividimos o estudo em duas etapas, sendo que na primeira avaliamos a participação dos receptores TRPV4 e TRPM8 nos mecanismos contráteis e relaxantes do detrusor isolado de animais controles e knockout para esses canais. Em uma segunda etapa estudamos a ativação desses canais em camundongos diabéticos pela injeção intraperitoneal de estreptozotocina (180 mg/Kg) por 4 semanas. Em fragmentos do detrusor isolados de camundongos mostramos que o agonista do receptor TRPV4, GSK1016790A, causou resposta contrátil dependente da concentração. Por outro lado, quando os tecidos foram contraídos com solução despolarizante de KCl, o GSK1016790A causou relaxamento da preparação. No detrusor isolado de animais TRPV4-/- verificamos hipercontratilidade ao carbacol (agonista muscarínico) e à estimulação elétrica, assim como redução no relaxamento ao agonista ?-adrenérgico não-seletivo, isoprenalina. Estes efeitos não foram obtidos com os antagonistas dos receptores TRPV4, RN1734 e HC067047. A indução do diabetes causou nocicepção mecânica e aumento da proporção entre bexiga e peso corpóreo após 4 semanas da injeção. A avaliação miccional dos animais diabéticos mostrou aumento da capacidade, frequência urinária e das contrações involuntárias da bexiga. Observamos ainda hipercontratilidade do detrusor ao carbacol, à estimulação elétrica e ao KCl. A indução do diabetes em animais TRPV4-/- não modificou as disfunções "in vivo" e "in vitro" observadas nos animais wyld type diabéticos, mostrando que a ausência crônica dos receptores TRPV4 desencadeia alterações miccionais que são anteriores as causadas pelo diabetes. Também verificamos que os animais TRPM8-/- não apresentam alteração na resposta contrátil ao carbacol e à estimulação elétrica. Por outro lado, o mentol, mas não a icilina, reduziu significativamente as respostas contráteis nestes animais. O mentol inibiu o influxo de cálcio extracelular em cultura de células da musculatura lisa da bexiga por mecanismo inibitório direto nos canais Cav1.2. O tratamento agudo com mentol, intraperitoneal e intravesical, atenuou as disfunções miccionais observadas nos camundongos diabéticos. "In vitro" o pré-tratamento com mentol reduziu a hipercontratilidade ao carbacol no grupo diabético, sem alterar a resposta no grupo controle. Concluímos que o mentol impede a resposta contrátil da bexiga por mecanismo independente do receptor TRPM8 bloqueando o influxo de cálcio extracelular nos canais Cav1,2, podendo ser utilizado como tratamento na hiperatividade de bexiga de origem miogênica
Abstract: The TRPV4 and TRPM8 receptors are expressed in bladder urothelium and sensitive afferent fibers. Physiologically, the mechanical activation of TRPV4 receptor in the bladder wall is involved in micturition control. In inflammatory diseases, these receptors may have important roles. The bladder dysfunction in diabetes may be associated with changes at the level of detrusor, innervation and urothelium. The urothelial dysfunction triggers neural changes, modifying consequently the smooth muscle contractility. Thus, the goal of the present study was to investigate the pathophysiological mechanisms of TRPV4 and TRPM8 receptor activation in physiological and diabetic conditions in mice. For this purpose we divided the study in two phases, the first of which we evaluated the participation of TRPV4 and TRPM8 receptors in detrusor contractile and relaxing mechanisms in control and knockout animals for these channels. In the second phase we studied the activation of these channels in diabetic mice induced by intraperitoneal injection of streptozotocin (STZ; 180 mg / kg, 4 weeks). The TRPV4 agonist GSK1016790A produced concentration-dependent detrusor contractions. On the other hand, in detrusor pré-contracted with KCl (80 mM), GSK1016790A caused relaxation responses. In TRPV4-/- animals, we verified hypercontractility to carbachol (muscarinic agonist) and electrical-field stimulation, as well as a decreased relaxation to isoprenaline (non-selective ?-adrenergic agonist). These effects were not obtained with the TRPV4 antagonists, RN1734 and HC067047. Induction of diabetes with STZ caused hyperglycemia, mechanical nocicepton, and increased ratio between bladder and body weight after 4 weeks. The miccturition evaluationin diabetic animals showed increased capacity, urinary frequency, and non-voiding contractions. Hypercontractility to carbachol, electrical-field stimulation and KCl in isolated detrusor were lso observed. The induction of diabetes in TRPV4-/- animals did not change the urinary dysfunctions. Our data are consistent with the proposal that TRPV4 receptor has a physiological function in micturition control by decreasing muscarinic-induced contractions and increasing ?-adrenergic-mediated relaxations. Moreover, the bladder contractions to carbachol and EFS in TRPM8-/- did not significantly change compared to TRPM8+/+. However, menthol (300 ?M), but not icilin (1 ?M), significantly inhibited these contractile responses. The menthol (300 ?M) inhibited extracellular calcium influx in bladder smooth muscle cell culture by direct mechanism though Cav1.2 channels. In addition the acute treatment with menthol, intraperitoneal and intravesical, atenuated the micturition dysfunctions observed in diabetic mice. Also, detrusor preparations pre-treated with menthol decreased carbachol hypercontractility, without changing the responses in normoglycemic group. Menthol reduces bladder contractions by mechanisms independent of TRPM8 receptor activation, inhibiting extracellular calcium influx through Cav1.2 channel, thus been considered as treatment for bladder overactivity of myogenic origin
Doutorado
Farmacologia
Doutor em Farmacologia
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Csályi, Kitti Dóra [Verfasser]. "Identification of molecular mechanisms of Wnt11 non-canonical signaling in regulation of L-type calcium channel / Kitti Dóra Csályi." Berlin : Freie Universität Berlin, 2018. http://d-nb.info/1176633686/34.
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RUBIO, MARTA. "A CALCIUM DEPENDENT MODEL OF HEART FAILURE: CHARACTERIZATION AND MECHANISMS TOWARDS PREVENTION." University of Cincinnati / OhioLINK, 2005. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1120594279.
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Auguste, Gaëlle. "Le canal calcique de type L, une cible directe de l’aldostérone dans les cardiomyocytes." Thesis, Paris 11, 2015. http://www.theses.fr/2015PA114803.
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Ces dernières décennies ont mis à jour une implication pathologique nouvelle del’aldostérone, via le récepteur aux minéralocorticoïdes (RM) dans le coeur. L’ensemble desdonnées issues des études expérimentales et des essais cliniques suggère une association délétèreentre l’aldostérone et la survenue d’arythmies. L’utilisation d’antagonistes du RM prévient cesarythmies. Cependant, les voies de signalisations, comme les mécanismes moléculaires soustendantces effets bénéfiques du blocage des RM demeurent incertains. Nous avons accumulésdes preuves d’une modulation de la signalisation calcique dans le cardiomyocyte, et en particulierde l’influx calcique (Ca2+) au travers du canal Ca2+ de type L (LTCC). Celui-Ci pourrait être unecible primaire de l’aldostérone et du RM dans les cardiomyocytes ventriculaires. Toutefois, lesmécanismes par lesquels l’aldostérone et le RM régulent l’expression du LTCC restent à définir.Au cours de ces travaux menés sur cardiomyocytes de rats nouveau-Nés, nous avonsétudiés les évènements moléculaires par lesquels l’aldostérone exerce ses effets sur le CaV1.2,qui correspond à la sous-Unité principale du LTCC formant le pore du canal ; cette protéine estcodée par le CACNA1C. Par microscopie confocale, nous avons suivi en temps réel le traffickingnucléo-Cytoplasmique du RM couplé à la GFP en réponse à l’aldostérone, démontrant ainsi queles RM cardiaques sont fonctionnels. Le traitement durant 24 heures des cardiomyocytes avec del’aldostérone montre une augmentation dose-Dépendante des protéines et de l’ARN messager duCaV1.2. L’utilisation de la technique du gène rapporteur de la luciférase permet l’analyse del’activité du promoteur du CaCNA1C. Celui-Ci montre une activité transcriptionnelle dose ettemps dépendante en réponse à l’aldostérone. De plus, ces effets sont dépendant des RM carinhibés en présence de RU28318, un antagoniste sélectif du RM, ou par l’utilisation de siRNAdirigés contre le RM. L’analyse in silico de la séquence du promoteur du CaCNA1C nous a permisd’identifier cinq séquences putatives correspondant à des éléments de réponse auxglucocorticoïdes (GRE). La mutation du site le plus lointain du site d’initiation de la transcriptionne révèle aucun changement dans les réponses transcriptionnelles induites par un RM humainconstitutivement actif (hMRΔ5,6) ou dans les réponses doses-Dépendantes de l’aldostérone ou dela déxaméthasone, un glucocorticoïde de synthèse. La mutation des trois sites GRE putatifssuivants provoque une diminution des réponses au hMRΔ5,6 comme à l’aldostérone, alors que lesréponses à la déxaméthasone sont soit inchangées, soit augmentées. En contraste, la mutation dusite le plus proximal du promoteur augmente de façon importante l’activité transcriptionnelle dupromoteur en réponse au hMRΔ5,6, à l’aldostérone comme à la déxaméthasone.Ces résultats démontrent que le LTCC cardiaque constitue une cible directe del’aldostérone et du RM, et apportent de nouvelles perspectives quant aux conséquencesmoléculaires et fonctionnelles engendrées par l’activation délétère du système minéralocorticoïdedans la défaillance cardiaqueDuring the past decades, major novel pathogenic roles of the steroid hormone,aldosterone, via the Mineralocorticoid Receptor (MR) have been identified in heart. Collectively,experimental studies and clinical trials, suggest a detrimental association between aldosteroneand life threatening arrhythmias that may be prevented by MR blockade. However, the signalingpathways and underlying mechanisms still remain elusive. We have accumulated evidence thatmodulation of Ca2+ signaling, especially Ca2+ influx via L-Type Ca2+ channel (LTCC), might bethe primary aldosterone/MR target in ventricular cardiomyocytes. Yet, the molecularmechanisms by which MR regulates expression of LTCC remain to be defined. Here, weinvestigated, in primary cultures of neonatal rat ventricular myocytes, the molecular eventscritical for aldosterone-Mediated cardiac effects on CaV1.2, the pore-Forming main subunit ofLTCC, which is encoded by the CaCNA1C gene.We showed that cardiac MR are functional as demonstrated by aldosterone-Induced MRnucleocytoplasmic trafficking observed by time-Lapse imaging of transfected GFP-Labeled MRusing confocal microscopy. Aldosterone exposure for 24 hours, induced a dose-Dependentincrease in CaV1.2 expression at both mRNA and protein levels. Analysis of the CaCNA1Cpromoter activity using luciferase reporter assays, revealed a dose- and time-Dependent activationby aldosterone. These effects were inhibited in the presence of either RU28318, a selective MRantagonist, or MR siRNA. In silico analyze enabled us to identify five putative GlucocorticoidResponse Elements (GRE) within the CaCNA1C promoter sequence. The mutation of the mostdistal GRE from Transcription Start Site (TSS) did not altered responses either elicited by theconstitutively active human MR (hMRΔ5,6) or dose-Dependent effects of aldosterone anddexamethasone (a synthetic glucocorticoïd with minimal MR effect). Mutations of the three nextones decreased responses to hMRΔ5,6 and aldosterone, whereas dexamethasone responses wereeither unchanged or increased. In sharp contrast, the mutation of the most proximal GRE fromTSS, increased responses to hMRΔ5,6, aldosterone and dexamethasone.These results provide new insights into the molecular mechanisms associated with cardiacMR activation, and suggest that LTCC is a primary MR target, with subsequent molecular andfunctional consequences that could lead to MR-Related cardiac dysfunction
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Earl, Damien E. "Regulation of Neuronal L-type Voltage-Gated Calcium Channels by Flurazepam and Other Positive Allosteric GABAA Receptor Modulators." University of Toledo Health Science Campus / OhioLINK, 2011. http://rave.ohiolink.edu/etdc/view?acc_num=mco1307379688.
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Cruz, Garcia Yiliam [Verfasser], Michaela [Gutachter] Kuhn, and Thomas [Gutachter] Dandekar. "Interactome of the β2b subunit of L-type voltage-gated calcium channels in cardiomyocytes / Yiliam Cruz Garcia ; Gutachter: Michaela Kuhn, Thomas Dandekar." Würzburg : Universität Würzburg, 2021. http://d-nb.info/1237623189/34.
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Roberts-Crowley, Mandy L. "Modulation of Cav1.3 L-Type Calcium Channels by Arachidonic Acid and Muscarinic M1 Receptors: A Dissertation." eScholarship@UMMS, 2007. https://escholarship.umassmed.edu/gsbs_diss/348.
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Membrane excitability, gene expression, and neurotransmitter release are all controlled by voltage-gated L-type Ca2+ (L- )channels. In turn, Ca2+ channels are highly regulated by signal transduction cascades initiated by G protein-coupled receptor (GPCR) activation. In medium spiny neurons of the striatum, both the muscarinic M1 receptors (M1R) and dopaminergic D2 receptors (D2R) specifically inhibit the Cav1.3 L-channel.
In Chapters III and IV, the pathways downstream of M1Rs and D2Rs are examined to determine whether an overlap or intersection in inhibition of Cav1.3 occurs by these two receptors. Transient transfection of Cav1.3 channels in HEK 293 cells, stably transfected with the M1R, and in ST14A cells were used as model systems. While a further characterization of ST14A cells determined that they exhibit a striatal profile, D2Rs or M1Rs did not inhibit Cav1.3. Lack of current inhibition may be due to the finding of no detectable expression of phospholipase Cβ-1 protein in ST14A cells.
Ca2+ channels are multiprotein complexes comprised of α1, β, and α2δ subunits. While the actions of arachidonic acid (AA) have been shown to mimic M1R inhibition of L-current in superior cervical ganglion neurons, the precise identity of the L-channel in these neurons -either Cav1.2 or Cav1.3 or both- is not known. The transfected model systems allowed for the analysis of whole-cells currents with different β subunit combinations as well as the study of only Cav1.3 channels. In Chapter III, I show that activation of M1Rs with the agonist Oxo-M inhibited Cav1.3 channels coexpressed with either β1b, β2a, β3, or β4 subunits. Surprisingly, the magnitude of Cav1.3, β2a currents was inhibited less than Cav1.3 currents with other β subunits. In Chapter V, AA is shown to mimic the profile of M1R stimulation on Cav1.3 currents. The magnitude of Cav1.3, β2a currents was inhibited less than Cav1.3 currents with other β subunits by AA. This discovery points to a novel role for accessory β subunits in altering the magnitude of AA inhibition and kinetic changes of Cav1.3.
Arachidonic acid (AA) inhibits Ca2+ channels by an unknown mechanism at an unknown site. In Chapter V, I found that Cavl.3 inhibition by AA was state-dependent and most likely stabilizes a closed channel conformation. The finding that the Ca2+ channel accessory β subunit alters the magnitude of AA inhibition and kinetic changes of Cav1.3 suggests that AA could alter processes which rely on L-channels such as Ca2+-dependent gene expression, secretion and membrane excitability.
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Zahratka, Jeffrey Allen. "Serotonin Modulates a Calcium-Driven Negative Feedback Loop in a C. elegans Nociceptor." University of Toledo / OhioLINK, 2015. http://rave.ohiolink.edu/etdc/view?acc_num=toledo1449748910.
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Xiang, Kun. "The role of L-type voltage-gated calcium channels in hippocampal CA1 neuron glutamate and GABA-A receptor-mediated synaptic plasticity following chronic benzodiazepine administration." Connect to Online Resource-OhioLINK, 2007. http://rave.ohiolink.edu/etdc/view?acc%5Fnum=mco1181737040.
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Dissertation (Ph.D.)--University of Toledo, 2007."In partial fulfillment of the requirements for the degree of Doctor of Philosophy in Biomedical Sciences." Title from title page of PDF document. Bibliography: p. 70-78, p. 93, p. 132-140, p. 164-168, p. 194-221.
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Hopp, Sarah Christine. "Microglia and calcium dysregulation during chronic neuroinflammation and aging:causes and consequences." The Ohio State University, 2014. http://rave.ohiolink.edu/etdc/view?acc_num=osu1414416679.
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Malick, Seemab. "Denitration in Colonic Smooth Muscle." VCU Scholars Compass, 2009. http://scholarscompass.vcu.edu/etd/1948.
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Tyrosine nitration results in altered function of smooth muscle voltage-gated L-type calcium channel. We explored the possibility that smooth muscle contains denitrase activity to allow functional recovery of the calcium channel without requiring synthesis of new channel proteins. Following peroxynitrite treatment of mouse colonic smooth muscle strips, CaCl2 (1 mM)-induced smooth muscle contraction was significantly reduced by 67% (P ≤ 0.05), which reversed by approximately 86% upon periodic washing within 2 hr period (P ≤ 0.001). The effect of the c-Src kinase inhibitor, PP2, on muscle contraction was also restored after 2 hr post-peroxynitrite treatment consistent with the thesis that recovery from tyrosine nitration allows for tyrosine phosphorylation of the calcium channel. In addition, sodium orthovanadate prevented nitration-induced inhibition of muscle contraction by approximately 90%. Moreover, denitration of nitrated proteins was observed by western blots in smooth muscle cells over 2 hr. Since nitrotyrosine formation interferes with tyrosine kinase pathways involved in cell signaling, the presence of denitrase activity in smooth muscle cells may have profound and important effects in restoring the function of nitrated proteins involved in cell signaling processes.