The Experts below are selected from a list of 1893 Experts worldwide ranked by ideXlab platform
René J. M. Bindels - One of the best experts on this subject based on the ideXlab platform.
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The epithelial calcium channels, TRPV5 & TRPV6: from identification towards regulation.
Cell calcium, 2020Co-Authors: Els Den Dekker, Bernd Nilius, Joost G J Hoenderop, René J. M. BindelsAbstract:The epithelial calcium channels, TRPV5 and TRPV6, have been extensively studied in epithelial tissues controlling the Ca(2+) homeostasis and exhibit a range of distinctive properties that distinguish them from other TRP channels. This review focuses on the tissue distribution, the functional properties, the architecture and the regulation of the expression and activity of the TRPV5 and TRPV6 channel.
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functional TRPV6 channels are crucial for transepithelial ca2 absorption
American Journal of Physiology-gastrointestinal and Liver Physiology, 2012Co-Authors: Titia E Woudenbergvrenken, René J. M. Bindels, Veit Flockerzi, Anke L Lameris, Petra Weisgerber, Jenny Olausson, Marc Freichel, Joost G J HoenderopAbstract:TRPV6 is considered the primary protein responsible for transcellular Ca2+ absorption. In vitro studies demonstrate that a negatively charged amino acid (D) within the putative pore region of mouse TRPV6 (position 541) is critical for Ca2+ permeation of the channel. To elucidate the role of TRPV6 in transepithelial Ca2+ transport in vivo, we functionally analyzed a TRPV6D541A/D541A knockin mouse model. After weaning, mice were fed a regular (1% wt/wt) or Ca2+-deficient (0.02% wt/wt) diet and housed in metabolic cages. Blood was sampled for Ca2+ measurements, and the expression of Ca2+ transport proteins was analyzed in kidney and duodenum. Intestinal 45Ca2+ uptake was measured in vivo by an absorption assay. Challenging the mice with the Ca2+-deficient diet resulted in hypocalcemia in wild-type and TRPV6D541A/D541A mice. On a low-Ca2+ diet both mouse strains displayed increased expression of intestinal TRPV6, calbindin-D9K, and renal TRPV5. TRPV6D541A/D541A mice showed significantly impaired intestinal Ca...
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The role of transient receptor potential channels in kidney disease.
Nature Reviews Nephrology, 2009Co-Authors: Titia E. Woudenberg-vrenken, René J. M. Bindels, Joost G J HoenderopAbstract:The transient receptor potential (TRP) superfamily consists, in mammals, of six protein subfamilies, TRPC, TRPM, TRPV, TRPA, TRPML and TRPP. TRPs are cation channels involved in many physiological processes and in the pathogenesis of various disorders. In the kidney, TRP channels are expressed along the nephron, and a role for some of these channels in renal function has been proposed. TRPC3 is thought to facilitate calcium ion influx into the principal cells of the collecting duct in response to vasopressin. TRPM3 and TRPV4 might be osmosensors, whereas the TRPP1/TRPP2 complex could function as a mechanosensor in the cilia of renal epithelial cells. A number of kidney diseases have also been linked to dysfunctional activity of TRPs. TRPC6 dysfunction has been associated with the onset of focal segmental glomerosclerosis; TRPP2 dysfunction is linked to autosomal-dominant polycystic kidney disease, TRPM6 mutations underlie hypomagnesemia with secondary hypocalcemia, and TRPV1 dysfunction is implicated in renal hypertension. A link between TRPC1 dysfunction and diabetic nephropathy has also been suggested in an animal model. Animal studies have implicated a role for TRPV5 in idiopathic hypercalciuria and vitamin D-dependent rickets, although these observations have not been confirmed in patients. This Review focuses on the role of renal TRP channels in health and disease.
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the β glucuronidase klotho exclusively activates the epithelial ca2 channels trpv5 and TRPV6
Nephrology Dialysis Transplantation, 2008Co-Authors: Peng Lu, René J. M. Bindels, Sandor Boros, Qing Chang, Joost G J HoenderopAbstract:Background. Active Ca 2+ reabsorption in the kidney is facilitated by the epithelial transient receptor potential vanilloid Ca 2+ channel subtype 5 (TRPV5). The complexglycosylated TRPV5 is expressed at the apical membrane of the renal distal convoluted tubule (DCT) cells where the pro-urine hormone klotho can stimulate its activity by N-oligosaccharide hydrolysis. This study investigates whether klotho and its closely related analogue, β-glucuronidase, can activate other renal ion channels than TRPV5 expressed by DCT cells. Methods. To determine the specificity of this stimulatory effect of klotho and β-glucuronidase, a selection of ion channels and transporters expressed in the kidney (TRPV4, TRPV5, TRPV6 and TRPM6) was screened in transfected HEK293 cells by using Ca 2+ -influx measurements. Results. Klotho and β-glucuronidase have been found to significantly increase the activity of TRPV5 and TRPV6, but had no effect on TRPV4 and TRPM6. Furthermore, deglycosylation by endoglycosidase-F also stimulated the activityofTRPV4,TRPV5andTRPV6,butnotofTRPM6. Conclusions. These results suggest a modulating effect for klotho primarily restricted to the epithelial Ca 2+ channels TRPV5 and TRPV6.
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the beta glucuronidase klotho exclusively activates the epithelial ca2 channels trpv5 and TRPV6
Nephrology Dialysis Transplantation, 2008Co-Authors: Peng Lu, René J. M. Bindels, Sandor Boros, Qing Chang, Joost G J HoenderopAbstract:BACKGROUND: Active Ca(2+) reabsorption in the kidney is facilitated by the epithelial transient receptor potential vanilloid Ca(2+) channel subtype 5 (TRPV5). The complex-glycosylated TRPV5 is expressed at the apical membrane of the renal distal convoluted tubule (DCT) cells where the pro-urine hormone klotho can stimulate its activity by N-oligosaccharide hydrolysis. This study investigates whether klotho and its closely related analogue, beta-glucuronidase, can activate other renal ion channels than TRPV5 expressed by DCT cells. METHODS: To determine the specificity of this stimulatory effect of klotho and beta-glucuronidase, a selection of ion channels and transporters expressed in the kidney (TRPV4, TRPV5, TRPV6 and TRPM6) was screened in transfected HEK293 cells by using Ca(2+)-influx measurements. RESULTS: Klotho and beta-glucuronidase have been found to significantly increase the activity of TRPV5 and TRPV6, but had no effect on TRPV4 and TRPM6. Furthermore, deglycosylation by endoglycosidase-F also stimulated the activity of TRPV4, TRPV5 and TRPV6, but not of TRPM6. CONCLUSIONS: These results suggest a modulating effect for klotho primarily restricted to the epithelial Ca(2+) channels TRPV5 and TRPV6.
Joost G J Hoenderop - One of the best experts on this subject based on the ideXlab platform.
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The epithelial calcium channels, TRPV5 & TRPV6: from identification towards regulation.
Cell calcium, 2020Co-Authors: Els Den Dekker, Bernd Nilius, Joost G J Hoenderop, René J. M. BindelsAbstract:The epithelial calcium channels, TRPV5 and TRPV6, have been extensively studied in epithelial tissues controlling the Ca(2+) homeostasis and exhibit a range of distinctive properties that distinguish them from other TRP channels. This review focuses on the tissue distribution, the functional properties, the architecture and the regulation of the expression and activity of the TRPV5 and TRPV6 channel.
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trp channels in calcium homeostasis from hormonal control to structure function relationship of trpv5 and TRPV6
Biochimica et Biophysica Acta, 2017Co-Authors: Mark K Van Goor, Joost G J Hoenderop, Jenny Van Der WijstAbstract:Maintaining plasma calcium levels within a narrow range is of vital importance for many physiological functions. Therefore, calcium transport processes in the intestine, bone and kidney are tightly regulated to fine-tune the rate of absorption, storage and excretion. The TRPV5 and TRPV6 calcium channels are viewed as the gatekeepers of epithelial calcium transport. Several calciotropic hormones control the channels at the level of transcription, membrane expression, and function. Recent technological advances have provided the first near-atomic resolution structural models of several TRPV channels, allowing insight into their architecture. While this field is still in its infancy, it has increased our understanding of molecular channel regulation and holds great promise for future structure-function studies of these ion channels. This review will summarize the mechanisms that control the systemic calcium balance, as well as extrapolate structural views to the molecular functioning of TRPV5/6 channels in epithelial calcium transport.
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functional TRPV6 channels are crucial for transepithelial ca2 absorption
American Journal of Physiology-gastrointestinal and Liver Physiology, 2012Co-Authors: Titia E Woudenbergvrenken, René J. M. Bindels, Veit Flockerzi, Anke L Lameris, Petra Weisgerber, Jenny Olausson, Marc Freichel, Joost G J HoenderopAbstract:TRPV6 is considered the primary protein responsible for transcellular Ca2+ absorption. In vitro studies demonstrate that a negatively charged amino acid (D) within the putative pore region of mouse TRPV6 (position 541) is critical for Ca2+ permeation of the channel. To elucidate the role of TRPV6 in transepithelial Ca2+ transport in vivo, we functionally analyzed a TRPV6D541A/D541A knockin mouse model. After weaning, mice were fed a regular (1% wt/wt) or Ca2+-deficient (0.02% wt/wt) diet and housed in metabolic cages. Blood was sampled for Ca2+ measurements, and the expression of Ca2+ transport proteins was analyzed in kidney and duodenum. Intestinal 45Ca2+ uptake was measured in vivo by an absorption assay. Challenging the mice with the Ca2+-deficient diet resulted in hypocalcemia in wild-type and TRPV6D541A/D541A mice. On a low-Ca2+ diet both mouse strains displayed increased expression of intestinal TRPV6, calbindin-D9K, and renal TRPV5. TRPV6D541A/D541A mice showed significantly impaired intestinal Ca...
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The role of transient receptor potential channels in kidney disease.
Nature Reviews Nephrology, 2009Co-Authors: Titia E. Woudenberg-vrenken, René J. M. Bindels, Joost G J HoenderopAbstract:The transient receptor potential (TRP) superfamily consists, in mammals, of six protein subfamilies, TRPC, TRPM, TRPV, TRPA, TRPML and TRPP. TRPs are cation channels involved in many physiological processes and in the pathogenesis of various disorders. In the kidney, TRP channels are expressed along the nephron, and a role for some of these channels in renal function has been proposed. TRPC3 is thought to facilitate calcium ion influx into the principal cells of the collecting duct in response to vasopressin. TRPM3 and TRPV4 might be osmosensors, whereas the TRPP1/TRPP2 complex could function as a mechanosensor in the cilia of renal epithelial cells. A number of kidney diseases have also been linked to dysfunctional activity of TRPs. TRPC6 dysfunction has been associated with the onset of focal segmental glomerosclerosis; TRPP2 dysfunction is linked to autosomal-dominant polycystic kidney disease, TRPM6 mutations underlie hypomagnesemia with secondary hypocalcemia, and TRPV1 dysfunction is implicated in renal hypertension. A link between TRPC1 dysfunction and diabetic nephropathy has also been suggested in an animal model. Animal studies have implicated a role for TRPV5 in idiopathic hypercalciuria and vitamin D-dependent rickets, although these observations have not been confirmed in patients. This Review focuses on the role of renal TRP channels in health and disease.
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the beta glucuronidase klotho exclusively activates the epithelial ca2 channels trpv5 and TRPV6
Nephrology Dialysis Transplantation, 2008Co-Authors: Peng Lu, René J. M. Bindels, Sandor Boros, Qing Chang, Joost G J HoenderopAbstract:BACKGROUND: Active Ca(2+) reabsorption in the kidney is facilitated by the epithelial transient receptor potential vanilloid Ca(2+) channel subtype 5 (TRPV5). The complex-glycosylated TRPV5 is expressed at the apical membrane of the renal distal convoluted tubule (DCT) cells where the pro-urine hormone klotho can stimulate its activity by N-oligosaccharide hydrolysis. This study investigates whether klotho and its closely related analogue, beta-glucuronidase, can activate other renal ion channels than TRPV5 expressed by DCT cells. METHODS: To determine the specificity of this stimulatory effect of klotho and beta-glucuronidase, a selection of ion channels and transporters expressed in the kidney (TRPV4, TRPV5, TRPV6 and TRPM6) was screened in transfected HEK293 cells by using Ca(2+)-influx measurements. RESULTS: Klotho and beta-glucuronidase have been found to significantly increase the activity of TRPV5 and TRPV6, but had no effect on TRPV4 and TRPM6. Furthermore, deglycosylation by endoglycosidase-F also stimulated the activity of TRPV4, TRPV5 and TRPV6, but not of TRPM6. CONCLUSIONS: These results suggest a modulating effect for klotho primarily restricted to the epithelial Ca(2+) channels TRPV5 and TRPV6.
Bernd Nilius - One of the best experts on this subject based on the ideXlab platform.
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The epithelial calcium channels, TRPV5 & TRPV6: from identification towards regulation.
Cell calcium, 2020Co-Authors: Els Den Dekker, Bernd Nilius, Joost G J Hoenderop, René J. M. BindelsAbstract:The epithelial calcium channels, TRPV5 and TRPV6, have been extensively studied in epithelial tissues controlling the Ca(2+) homeostasis and exhibit a range of distinctive properties that distinguish them from other TRP channels. This review focuses on the tissue distribution, the functional properties, the architecture and the regulation of the expression and activity of the TRPV5 and TRPV6 channel.
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On the Origin of Bladder Sensing: Tr(i)ps in Urology
Neurourology and Urodynamics, 2020Co-Authors: Wouter Everaerts, Bernd Nilius, Thomas Gevaert, Dirk De RidderAbstract:The mammalian TRP family consists of 28 channels that can be subdivided into 6 different classes: TRPV (vanilloid), TRPC (canonical), TRPM (Melastatin), TRPP (Polycystin), TRPML (Mucolipin), and TRPA (Ankyrin). TRP channels are activated by a diversity of physical (voltage, heat, cold, mechanical stress) or chemical (pH, osmolality) stimuli and by binding of specific ligands, enabling them to act as multifunctional sensors at the cellular level. Currently, a lot of scientific research is devoted to these channels and their role in sensing mechanisms throughout the body. In urology, there’s a growing conviction that disturbances in afferent (sensory) mechanisms are highly important in the pathogenesis of functional problems. Therefore, the TRP family forms an interesting new target to focus on. In this review we attempt to summarize the existing knowledge about TRP channels in the urogenital tract. So far, TRPV1, TRPV2, TRPV4, TRPM8, and TRPA1 have been described in different parts of the urogenital tract. Although only TRPV1 (the vanilloid receptor) has been extensively studied so far, more evidence is slowly accumulating about the role of other TRP channels in the (patho)physiology of the urogenital tract. Neurourol. Urodynam. 27:264–273, 2008. 2007 Wiley-Liss, Inc.
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Pharmacology of Vanilloid Transient Receptor Potential Cation Channels
Molecular Pharmacology, 2009Co-Authors: Joris Vriens, Giovanni Appendino, Bernd NiliusAbstract:Depending on their primary structure, the 28 mammalian transient receptor potential (TRP) cation channels identified so far can be sorted into 6 subfamilies: TRPC (“Canonical”), TRPV (“Vanilloid”), TRPM (“Melastatin”), TRPP (“Polycystin”), TRPML (“Mucolipin”), and TRPA (“Ankyrin”). The TRPV subfamily (vanilloid receptors) comprises channels critically involved in nociception and thermosensing (TRPV1, TRPV2, TRPV3, and TRPV4), whereas TRPV5 and TRPV6 are involved in renal Ca 2 absorption/reabsorption. Apart from TRPV1, the pharmacology of these channels is still insufficiently known. Furthermore, only few small-molecule ligands for non-TRPV1 vanilloid receptors have been identified, and little is known of their endogenous ligands, resulting in a substantial “orphan” state for these channels. In this review, we summarize the pharmacological properties of members of the TRPV subfamily, highlighting the critical issues and challenges facing their “deorphanization” and clinical exploitation.
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Vanilloid Transient Receptor Potential Cation Channels : An Overview
Current Pharmaceutical Design, 2008Co-Authors: Rudi Vennekens, Grzegorz Owsianik, Bernd NiliusAbstract:The mammalian branch of the Transient Receptor Potential (TRP) superfamily of cation channels consists of 28 members. They can be subdivided in six main subfamilies: the TRPC (‘Canonical’), TRPV (‘Vanilloid’), TRPM (‘Melastatin’), TRPP (‘Polycystin’), TRPML (‘Mucolipin’) and the TRPA (‘Ankyrin’) group. The TRPV subfamily comprises channels that are critically involved in nociception and thermo-sensing (TRPV1, TRPV2, TRPV3, TRPV4) as well as highly Ca2+ selective channels involved in Ca2+ absorption/ reabsorption in mammals (TRPV5, TRPV6). In this review we summarize fundamental physiological properties of all TRPV members in the light of various cellular functions of these channels and their significance in the systemic context of the mammalian organism.
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regulation of the mouse epithelial ca2 channel TRPV6 by the ca 2 sensor calmodulin
Journal of Biological Chemistry, 2004Co-Authors: Tim T Lambers, Bernd Nilius, Joost G J Hoenderop, Freek A Weidema, René J. M. BindelsAbstract:Abstract TRPV5 and TRPV6 are members of the superfamily of transient receptor potential (TRP) channels and facilitate Ca2+ influx in a variety of epithelial cells. The activity of these Ca2+ channels is tightly controlled by the intracellular Ca2+ concentration in close vicinity to the channel mouth. The molecular mechanism underlying the Ca2+-dependent activity of TRPV5/TRPV6 is, however, still unknown. Here, the putative role of calmodulin (CaM) as the Ca2+ sensor mediating the regulation of channel activity was investigated. Overexpression of Ca2+-insensitive CaM mutants (CaM1234 and CaM34) significantly reduced the Ca2+ as well as the Na+ current of TRPV6- but not that of TRPV5-expressing HEK293 cells. By combining pull-down assays and co-immunoprecipitations, we demonstrated that CaM binds to both TRPV5 and TRPV6 in a Ca2+-dependent fashion. The binding of CaM to TRPV6 was localized to the transmembrane domain (TRPV6327–577) and consensus CaM-binding motifs located in the N (1–5-10 motif, TRPV688–97) and C termini (1–8-14 motif, TRPV6643–656), suggesting a mechanism of regulation involving multiple interaction sites. Subsequently, chimeric TRPV6/TRPV5 proteins, in which the N and/or C termini of TRPV6 were substituted by that of TRPV5, were co-expressed with CaM34 in HEK293 cells. Exchanging, the N and/or the C termini of TRPV6 by that of TRPV5 did not affect the CaM34-induced reduction of the Ca2+ and Na+ currents. These results suggest that CaM positively affects TRPV6 activity upon Ca2+ binding to EF-hands 3 and 4, located in the high Ca2+ affinity CaM C terminus, which involves the N and C termini and the transmembrane domain of TRPV6.
Stan F J Van De Graaf - One of the best experts on this subject based on the ideXlab platform.
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regulation of trpv5 and TRPV6 by associated proteins
American Journal of Physiology-renal Physiology, 2006Co-Authors: Stan F J Van De Graaf, Joost G J Hoenderop, René J. M. BindelsAbstract:The epithelial Ca2+ channels TRPV5 and TRPV6 are the most Ca2+-selective members of the TRP channel superfamily. These channels are the prime target for hormonal control of the active Ca2+ flux from the urine space or intestinal lumen to the blood compartment. Insight into their regulation is, therefore, pivotal in our understanding of the (patho)physiology of Ca2+ homeostasis. The recent elucidation of TRPV5/6-associated proteins has provided new insight into the molecular mechanisms underlying the regulation of these channels. In this review, we describe the various means of TRPV5/6 regulation, the role of channel-associated proteins herein, and the relationship between both processes.
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interaction of the epithelial ca2 channels trpv5 and TRPV6 with the intestine and kidney enriched pdz protein nherf4
Pflügers Archiv: European Journal of Physiology, 2006Co-Authors: Stan F J Van De Graaf, Joost G J Hoenderop, Annemiete W C M Van Der Kemp, Serge M Gisler, René J. M. BindelsAbstract:The epithelial Ca2+ channels TRPV5 and TRPV6 constitute the apical Ca2+ influx pathway in epithelial Ca2+ transport. PDZ proteins have been demonstrated to play a crucial role in the targeting or anchoring of ion channels and transporters in the apical domain of the cell. In this study, we describe the identification of NHERF4 (Na-Pi Cap2/IKEPP/PDZK2) as a novel TRPV5- and TRPV6-associated PDZ protein. NHERF4 was identified using two separate yeast two-hybrid screens with the carboxyl termini of TRPV5 and TRPV6 as bait. Binding of the carboxyl termini of TRPV5 and TRPV6 with NHERF4 was confirmed by GST pull-down assays using in-vitro-translated NHERF4 or lysates of Xenopus laevis oocytes expressing NHERF4. Furthermore, the interaction was confirmed by GST pull-down and co-immunoprecipitation assays using in-vitro-translated full-length TRPV5 and Xenopus oocytes or HEK293 cells co-expressing NHERF4 and TRPV5/TRPV6, respectively. The fourth PDZ domain of NHERF4 was sufficient for the interaction, although PDZ domain 1 also contributed to the binding. The binding site for NHERF4 localized in a conserved region in the carboxyl terminus of TRPV5 and was distinct from the binding site of the PDZ protein NHERF2. NHERF4 predominantly localized at the plasma membrane of X. laevis oocytes and HeLa cells. This localization was independent of the presence of TRPV5. Therefore, we hypothesize a role for this novel PDZ protein as a putative plasma membrane scaffold for the epithelial Ca2+ channels.
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direct interaction with rab11a targets the epithelial ca2 channels trpv5 and TRPV6 to the plasma membrane
Molecular and Cellular Biology, 2006Co-Authors: Stan F J Van De Graaf, Qing Chang, Joost G J Hoenderop, Arjen R Mensenkamp, René J. M. BindelsAbstract:TRPV5 and TRPV6 are the most Ca2+-selective members of the transient receptor potential (TRP) family of cation channels and play a pivotal role in the maintenance of Ca2+ balance in the body. However, little is known about the mechanisms controlling the plasma membrane abundance of these channels to regulate epithelial Ca2+ transport. In this study, we demonstrated the direct and specific interaction of GDP-bound Rab11a with TRPV5 and TRPV6. Rab11a colocalized with TRPV5 and TRPV6 in vesicular structures underlying the apical plasma membrane of Ca2+-transporting epithelial cells. This GTPase recognized a conserved stretch in the carboxyl terminus of TRPV5 that is essential for channel trafficking. Furthermore, coexpression of GDP-locked Rab11a with TRPV5 or TRPV6 resulted in significantly decreased Ca2+ uptake, caused by diminished channel cell surface expression. Together, our data demonstrated the important role of Rab11a in the trafficking of TRPV5 and TRPV6. Rab11a exerts this function in a novel fashion, since it operates via direct cargo interaction while in the GDP-bound configuration.
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regulation of the epithelial ca2 channels trpv5 and TRPV6 by 1alpha 25 dihydroxy vitamin d3 and dietary ca2
The Journal of Steroid Biochemistry and Molecular Biology, 2004Co-Authors: Stan F J Van De Graaf, Joost G J Hoenderop, Inge Boullart, René J. M. BindelsAbstract:Abstract Active, transepithelial Ca 2+ transport is a pivotal process in the regulation of Ca 2+ homeostasis and consists of three sequential steps: apical Ca 2+ influx, diffusion towards the basolateral membrane and subsequent extrusion into the blood compartment. TRPV5 and TRPV6 (renamed after ECaC1 and ECaC2/CaT1, respectively) constitute the rate-limiting influx step of transepithelial Ca 2+ transport and these highly selective Ca 2+ channels are controlled by several factors. This review focuses on the regulation of TRPV5 and TRPV6 abundance and/or activity by 1α,25-dihydroxyVitamin D 3 (1α,25(OH) 2 D 3 ), dietary Ca 2+ and the auxiliary protein pair S100A10/annexin 2. Finally, the implications for our understanding of transcellular Ca 2+ transport will be discussed.
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functional expression of the epithelial ca2 channels trpv5 and TRPV6 requires association of the s100a10 annexin 2 complex
The EMBO Journal, 2003Co-Authors: Stan F J Van De Graaf, Jean Prenen, Bernd Nilius, Joost G J Hoenderop, Dimitra Gkika, Dennis Lamers, Ursula Rescher, Volker Gerke, Olivier Staub, René J. M. BindelsAbstract:TRPV5 and TRPV6 constitute the Ca(2+) influx pathway in a variety of epithelial cells. Here, we identified S100A10 as the first auxiliary protein of these epithelial Ca(2+) channels using yeast two-hybrid and GST pull-down assays. This S100 protein forms a heterotetrameric complex with annexin 2 and associates specifically with the conserved sequence VATTV located in the C-terminal tail of TRPV5 and TRPV6. Of these five amino acids, the first threonine plays a crucial role since the corresponding mutants (TRPV5 T599A and TRPV6 T600A) exhibited a diminished capacity to bind S100A10, were redistributed to a subplasma membrane area and did not display channel activity. Using GST pull-down and co-immunoprecipitation assays we demonstrated that annexin 2 is part of the TRPV5-S100A10 complex. Furthermore, the S100A10-annexin 2 pair colocalizes with the Ca(2+) channels in TRPV5-expressing renal tubules and TRPV6-expressing duodenal cells. Importantly, downregulation of annexin 2 using annexin 2-specific small interfering RNA inhibited TRPV5 and TRPV6-mediated currents in transfected HEK293 cells. In conclusion, the S100A10-annexin 2 complex plays a crucial role in routing of TRPV5 and TRPV6 to plasma membrane.
Joost P. H. Schoeber - One of the best experts on this subject based on the ideXlab platform.
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Identification of Nipsnap1 as a novel auxiliary protein inhibiting TRPV6 activity
Pflügers Archiv - European Journal of Physiology, 2008Co-Authors: Joost P. H. Schoeber, Joost G J Hoenderop, Tim T Lambers, Annemiete W C M Van Der Kemp, Catalin N. Topala, Guénola Ricard, Martijn A. Huynen, René J. M. BindelsAbstract:The transient receptor potential vanilloid channels 5 and 6 (TRPV5/6) are the most Ca^2+-selective channels within the TRP superfamily of ion channels. These epithelial Ca^2+ channels are regulated at different intra- and extracellular sites by the feedback response of Ca^2+ itself, calciotropic hormones, and by TRPV5/6-associated proteins. In the present study, bioinformatics was used to search for novel TRPV5/6-associated genes. By including pull-down assays and functional analysis, Nipsnap1—a hitherto functionally uncharacterized globular protein—was identified as a novel factor involved in the regulation of TRPV6. Electrophysiological recordings revealed that Nipsnap1 abolishes TRPV6 currents. Subsequent biotinylation assays showed that TRPV6 plasma membrane expression did not change in the presence of Nipsnap1, suggesting that TRPV6 inhibition by Nipsnap1 is independently regulated from reduced cell surface channel expression. In addition, semi-quantitative reverse transcriptase PCR and immunohistochemical labeling of Nipsnap1 indicated that Nipsnap1 is expressed in mouse intestinal tissues—where TRPV6 is predominantly expressed—but that it does not co-localize with TRPV5 in the kidney. In conclusion, this study presents the first physiological function of Nipsnap1 as an associated protein inhibiting TRPV6 activity that possibly exerts its effect directly at the plasma membrane.
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concerted action of associated proteins in the regulation of trpv5 and TRPV6
Biochemical Society Transactions, 2007Co-Authors: Joost P. H. Schoeber, Joost G J Hoenderop, René J. M. BindelsAbstract:Ca 2+ is an essential ion in all organisms and many physiological functions in the body rely on the exact maintenance of the Ca 2+ balance. The epithelial Ca 2+ channels TRPV5 [TRP (transient receptor potential) vanilloid 5] and TRPV6 are the most Ca 2+ -selective members of the TRP superfamily and are generally considered as the gatekeepers of Ca 2+ entry across epithelia. TRPV5 is involved in Ca 2+ reabsorption from pro-urine, while TRPV6 has an essential role in intestinal Ca 2+ uptake. These channels are the prime targets of calciotropic hormonal regulation, including vitamin D and parathyroid hormone. In addition, extra- and intra-cellular signalling by associated proteins and Ca 2+ itself play key roles in TRPV5 and TRPV6 regulation. In this paper, we describe the present understanding of the concerted action of calbindin-D28k ,k lotho and BSPRY (B-box and SPRY-domain-containing protein) at different levels throughout the epithelial cell to control Ca 2+ influx at the luminal entry gate.
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rgs2 inhibits the epithelial ca2 channel TRPV6
Journal of Biological Chemistry, 2006Co-Authors: Joost P. H. Schoeber, Joost G J Hoenderop, Tim T Lambers, Catalin N. Topala, Xinhua Wang, Robin J W Diepens, René J. M. BindelsAbstract:Abstract The epithelial Ca2+ channels TRPV5 and TRPV6 constitute the apical Ca2+ entry pathway in the process of active Ca2+ (re)absorption. By yeast two-hybrid and glutathione S-transferase pulldown analysis we identified RGS2 as a novel TRPV6-associated protein. RGS proteins determine the inactivation kinetics of heterotrimeric G-protein-coupled receptor (GPCR) signaling by regulating the GTPase activity of Gα subunits. Here we demonstrate that TRPV6 interacts with the NH2-terminal domain of RGS2 in a Ca2+-independent fashion and that overexpression of RGS2 reduces the Na+ and Ca2+ current of TRPV6 but not that of TRPV5-transfected human embryonic kidney 293 (HEK293) cells. In contrast, overexpression of the deletion mutant ΔN-RGS2, lacking the NH2-terminal domain of RGS2, in TRPV6-expressing HEK293 cells did not show this inhibition. Furthermore, cell surface biotinylation indicated that the inhibitory effect of RGS2 on TRPV6 activity is not mediated by differences in trafficking or retrieval of TRPV6 from the plasma membrane. This effect probably results from the direct interaction between RGS2 and TRPV6, affecting the gating properties of the channel. Finally, the scaffolding protein spinophilin, shown to recruit RGS2 and regulate GPCR-signaling via Gα, did not affect RGS2 binding and electrophysiological properties of TRPV6, indicating a GPCR-independent mechanism of TRPV6 regulation by RGS2.
