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Joost G J Hoenderop - One of the best experts on this subject based on the ideXlab platform.
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urinary β galactosidase stimulates ca2 transport by stabilizing TRPV5 at the plasma membrane
Glycobiology, 2016Co-Authors: Elizabeth H P Leunissen, Jenny Van Der Wijst, Rene J M Bindels, Maxime G Blanchard, Fareeba Sheedfar, Marla Lavrijsen, Joost G J HoenderopAbstract:Transcellular Ca(2+)transport in the late distal convoluted tubule and connecting tubule (DCT2/CNT) of the kidney is a finely controlled process mediated by the transient receptor potential vanilloid type 5 (TRPV5) channel. A complex-type-N-glycan bound at the extracellular residue Asn358 of TRPV5 through post-translational glycosylation has been postulated to regulate the activity of TRPV5 channels. Using in vitro Ca(2+)transport assays, immunoblot analysis, immunohistochemistry, patch clamp electrophysiology and total internal reflection fluorescence microscopy, it is demonstrated that the glycosidase β-galactosidase (β-gal), an enzyme that hydrolyzes galactose, stimulates TRPV5 channel activity. However, the activity of the non-glycosylated TRPV(N358Q)mutant was not altered in the presence of β-gal, showing that the stimulation is dependent on the presence of the TRPV5N-glycan. In addition, β-gal was found to stimulate transcellular Ca(2+)transport in isolated mouse primary DCT2/CNT cells. β-gal expression was detected in the apical membrane of the proximal tubules, and the protein was found in mouse urine. In summary, β-gal is present in the pro-urine from where it is thought to stimulate TRPV5 activity.
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the beta glucuronidase klotho exclusively activates the epithelial ca2 channels TRPV5 and trpv6
Nephrology Dialysis Transplantation, 2008Co-Authors: Peng Lu, 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.
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the β glucuronidase klotho exclusively activates the epithelial ca2 channels TRPV5 and trpv6
Nephrology Dialysis Transplantation, 2008Co-Authors: Peng Lu, Sandor Boros, Qing Chang, Rene J M Bindels, 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: Sandor Boros, Qing Chang, Rene J M Bindels, 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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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: Joost G J Hoenderop, Stan F J Van De Graaf, Annemiete W C M Van Der Kemp, Serge M GislerAbstract: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.
Bernd Nilius - One of the best experts on this subject based on the ideXlab platform.
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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 transient receptor potential trp channels by phosphoinositides
Pflügers Archiv: European Journal of Physiology, 2007Co-Authors: Tibor Rohacs, Bernd NiliusAbstract:This review summarizes the modulation of transient receptor potential (TRP) channels, by phosphoinositides. TRP channels are characterized by polymodal activation and a surprising complexity of regulation mechanisms. Possibly, most if not all TRP channels are modulated by phosphoinositides. Modulation by phosphatidylinositol 4,5-biphosphate (PIP2) has been shown in detail for TRP vanilloid (TRPV) 1, TRPV5, TRP melastatin (TRPM) 4, TRPM5, TRPM7, TRPM8, TRP polycystin 2, and the Drosophila TPR-like (TRPL) channels. This review describes mechanisms of modulation of TRP channels mainly by PIP2 and discusses some future challenges of this fascinating topic.
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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, Freek A Weidema, Bernd Nilius, Joost G J HoenderopAbstract: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.
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trpv channels and modulation by hepatocyte growth factor scatter factor in human hepatoblastoma hepg2 cells
Cell Calcium, 2004Co-Authors: Joris Vriens, Jean Prenen, Annelies Janssens, Bernd Nilius, Robert WondergemAbstract:Abstract Using patch clamp and Ca 2+ imaging techniques, we have studied Ca 2+ entry pathways in human hepatoblastoma (HepG2) cells. These cells express the mRNA of TRPV1, TRPV2, TRPV3 and TRPV4 channels, but not those of TRPV5 and TRPV6. Functional assessment showed that capsaicin (10 μM), 4α-phorbol-12,13-didecanoate (4αPDD, 1 μM), arachidonic acid (10 μM), hypotonic stress, and heat all stimulated increases in [Ca 2+ ] i within minutes. The increase in [Ca 2+ ] i depended on extracellular Ca 2+ and on the transmembrane potential, which indicated that both driving forces affected Ca 2+ entry. Capsaicin also stimulated an increase in [Ca 2+ ] i in nominally Ca 2+ -free solutions, which was compatible with the receptor functioning as a Ca 2+ release channel. Hepatocyte growth factor/scatter factor (HGF/SF) modulated Ca 2+ entry. Ca 2+ influx was greater in HepG2 cells incubated with HGF/SF (20 ng/ml for 20 h) compared with non-stimulated cells, but this occurred only in those cells with a migrating phenotype as determined by presence of a lamellipodium and trailing footplate. The effect of capsaicin on [Ca 2+ ] i was greater in migrating HGF/SF-treated cells, and this was inhibited by capsazepine. The difference between control and HGF/SF-treated cells was not found in Ca 2+ -free solutions. 4αPDD also had no greater effect on HGF/SF-treated cells. We conclude that TRPV1 and TRPV4 channels provide Ca 2+ entry pathways in HepG2 cells. HGF/SF increases Ca 2+ entry via TRPV1, but not via TRPV4. This rise in [Ca 2+ ] i may constitute an early response of a signalling cascade that gives rise to cell locomotion and the migratory phenotype.
Praful S Singru - One of the best experts on this subject based on the ideXlab platform.
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transient receptor potential vanilloid 1 6 trpv1 6 gene expression in the mouse brain during estrous cycle
Brain Research, 2018Co-Authors: Omprakash Singh, Uday Singh, Praful S Singru, Chandan Goswami, Santosh KumarAbstract:In recent years estradiol has emerged as a potential regulator of transient receptor potential vanilloid (TRPV) cationic channels in the peripheral tissues and sensory neurons, however, its analogous role in the CNS is poorly understood. TRPV channels modulate Ca2+ signalling, neurotransmission and behaviour, and expression of these ion channels and estrogen receptors show a great degree of overlap in different brain regions. Herein, we probe if Trpv1-6 genes contain estrogen receptor-binding sites and if their expression in different brain regions is modulated during estrous cycle. Bioinformatics analysis of the mouse Trpv1-6 gene sequences showed presence of putative functional estrogen response element in their promoter regions. Using qRT-PCR, Trpv1-6 mRNA expression was observed in the olfactory bulb, cortex, hypothalamus, hippocampus, brainstem, and cerebellum of mouse. In these regions, compared to estrus, metestrus, and diestrus, reduced levels of Trpv1 and TRPV5 but elevated Trpv2 and Trpv6 mRNA levels were observed during proestrus. Lower levels of Trpv3 and Trpv4 mRNAs were seen during estrus but higher expression of Trpv3 during metestrus and diestrus, and Trpv4 during proestrus was observed. Estradiol seems to regulate Trpv1/TRPV5 and Trpv2/Trpv6 mRNA expression in opposite manner. Except Trpv4 mRNA expression in the hippocampus and Trpv6 expression in the olfactory bulb, hippocampus and brainstem, expression of other members of TRPV subfamily in distinct brain regions of male mice was comparable to those in metestrus and diestrus mice. We suggest that the circulating levels of estradiol during the estrous cycle may differentially regulate the activity of TRPV1-6 ion channels in the brain.
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transient receptor potential vanilloid 5 TRPV5 a highly ca2 selective trp channel in the rat brain relevance to neuroendocrine regulation
Journal of Neuroendocrinology, 2017Co-Authors: Uday Singh, Praful S Singru, Chandan Goswami, Santosh KumarAbstract:Recent studies suggest an important role for transient receptor potential vanilloid (TRPV) ion channels in neural and neuroendocrine regulation. The TRPV subfamily consists of six members: TRPV1-6. While the neuroanatomical and functional correlates of TRPV1-4 have been studied extensively, relevant information about TRPV5 and TRPV6, which are highly selective for Ca2+ , is limited. We detected TRPV5 mRNA expression in the olfactory bulb, cortex, hypothalamus, hippocampus, midbrain, brainstem and cerebellum of the rat. TRPV5-immunoreactive neurones were conspicuously seen in the hypothalamic paraventricular (PVN), supraoptic (SON), accessory neurosecretory (ANS), supraoptic nucleus, retrochiasmatic part (SOR), arcuate (ARC) and medial tuberal nuclei, hippocampus, midbrain, brainstem and cerebellum. Glial cells also showed TRPV5-immunoreactivity. To test the neuroendocrine relevance of TRPV5, we focused on vasopressin, oxytocin and cocaine- and amphetamine-regulated transcript (CART) as representative candidate markers with which TRPV5 may co-exist. In the hypothalamic neurones, co-expression of TRPV5 was observed with vasopressin (PVN: 50.73±3.82%; SON: 75.91±2.34%; ANS: 49.12±4.28%; SOR: 100%) and oxytocin (PVN: 6.88±1.21; SON: 63.34±5.69%; ANS: 20.4±4.14; SOR: 86.5±1.74%). While ARC neurones express oestrogen receptors, 17β-oestradiol regulates TRPV5, as well as CART neurones and astrocytes, in the ARC. Furthermore, ARC CART neurones are known to project to the preoptic area, and innervate and regulate GnRH neurones. Using double-immunofluorescence, glial fibrillary acidic protein-labelled astrocytes and the majority of CART neurones in the ARC showed TRPV5-immunoreactivity. Following iontophoresis of retrograde neuronal tracer, cholera toxin β (CtB) into the anteroventral periventricular nucleus and median preoptic nucleus, retrograde accumulation of CtB was observed in most TRPV5-equipped ARC CART neurones. Next, we determined the response of TRPV5-elements in the ARC during the oestrous cycle. Compared to pro-oestrus, a significant increase (P<.001) in the percentage of TRPV5-expressing CART neurones was observed during oestrus, metoestrus, and dioestrus. TRPV5-immunoreactivity in the astrocytes, however, showed a significant increase during metoestrus and dioestrus. We suggest that the TRPV5 ion channel may serve as an important regulator of neural and neuroendocrine pathways in the brain.
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transient receptor potential vanilloid 6 trpv6 in the mouse brain distribution and estrous cycle related changes in the hypothalamus
Neuroscience, 2017Co-Authors: Omprakash Singh, Uday Singh, Praful S Singru, Chandan Goswami, Santosh KumarAbstract:Transient receptor potential vanilloid (TRPV) subfamily of cationic channels have emerged as novel players in neural regulation. Unlike other members of TRPV subfamily, TRPV5 and TRPV6 are highly Ca2+-selective. Although TRPV5/TRPV6 transcripts are expressed in mouse brain, understanding the full functional spectrum of these ion channels in the brain is however limited due to the lack of information on their neuroanatomical distribution. We have studied TRPV6 in mouse brain in further detail. In the hypothalamus, while Western blot analysis using TRPV6 specific antiserum showed a distinct ∼95 kDa band corresponding to the molecular weight of TRPV6, transcripts for TRPV6 were detected with RT-PCR. TRPV6-immunoreactive cells/fibers were observed in vascular organ of the lamina terminalis, olfactory bulb, amygdala, hippocampus, septohypothalamic, supraoptic, arcuate (ARC), dorsomedial, and subincertal nuclei. TRPV6-immunoreactive cells/fibers were also observed in the brainstem and cerebellum. Estrogen has emerged as a potential regulator of TRPV6 in peripheral tissues. TRPV6 gene promoter contains estrogen-response element, estrogen activates TRPV6 via estrogen receptor alpha (ERα), and ERα-expressing ARC neurons in mediobasal hypothalamus (MBH) serve as primary site for estradiol feedback. Using double immunofluorescence, co-expression of TRPV6 and ERα was observed in several ARC neurons. MBH of mice during different phases of estrous cycle were subjected to Western blot analysis of TRPV6. Compared to proestrus, a significant reduction (P < 0.01) in intensity of TRPV6-immunoreactive band was observed in MBH during metestrus and diestrus phases. While the wide distribution of TRPV6-expressing elements in the brain suggests its role in a range of CNS functions, the ion channel may serve as novel component of the neural pathway mediating effects of estradiol in MBH.
Wolfgang Liedtke - One of the best experts on this subject based on the ideXlab platform.
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Osmomechanical-Sensitive TRPV Channels in Mammals
Neurobiology of TRP Channels, 2017Co-Authors: Carlene Moore, Wolfgang LiedtkeAbstract:Within the transient receptor potential (TRP) superfamily of ion channels (Cosens and Manning, 1969; Montell and Rubin, 1989; Wong et al., 1989; Hardie and Minke, 1992; Zhu et al., 1995), the TRPV subfamily stepped into the limelight in 1997 (Colbert et al., 1997; Caterina et al., 1997), when its founding members, OSM-9 in Caenorhabditis elegans and TRPV1 in mammals, were first reported. OSM-9 was identified through genetic screening for worms’ defects in osmotic avoidance (Colbert et al., 1997). TRPV1 was identified by an expression cloning strategy (Caterina et al., 1997). (This is also true for TRPV5 and TRPV6, which will not be discussed in this chapter because, up to now, they have not been implicated in osmotic and mechanical signaling.) TRPV2, TRPV3, and TRPV4 were identified by a candidate gene approach, respectively (Caterina and Julius, 1999; Peier et al., 2002; Gunthorpe et al., 2002; Xu et al., 2002; Kanzaki et al., 1999; Liedtke et al., 2000; Strotmann et al., 2000; Wissenbach et al., 2000). The latter strategy also led to the identification of four additional C. elegans ocr genes (Tobin et al., 2002) and two Drosophila trpv genes, Nanchung (NAN) and Inactive (IAV) (Kim et al., 2003; Gong et al., 2004). The TRPV channels can be subgrouped into four branches by sequence comparison. One branch includes four members of mammalian TRPVs, TRPV1, TRPV2, TRPV3, and TRPV4; in vitro whole cell recording showed that they respond to temperatures higher than 42°C, 52°C, 31°C, and 27°C, respectively, suggesting that they are involved in thermosensation, hence the term thermo-TRPs. Illuminating review articles on thermo-TRPs are available for in-depth reading (Clapham, 2003; Patapoutian, 2005; Tominaga and Caterina, 2004; Caterina and Julius, 1999; Caterina and Montell, 2005). The second mammalian branch includes the Ca2+-selective channels, TRPV5 and TRPV6, possibly subserving Ca2+ uptake in the kidney and intestine (Hoenderop et al., 1999; den Dekker et al., 2003; Peng et al., 1999, 2003). One invertebrate branch includes C. elegans OSM-9 and Drosophila IAV; the other branch comprises OCR-1 to OCR-4 in C. elegans and Drosophila NAN.This chapter elucidates the role of mammalian TRPV channels in signal transduction in response to osmotic and mechanical stimuli, as well as provides comments on selected recent insights regarding other TRP ion channels that respond to osmotic and mechanical cues. These “osmo- and mechano-TRPs” (Liedtke and Kim, 2005) are TRPV1 (Sharif-Naeini et al., 2006; Zaelzer et al., 2015), TRPV2 (Muraki et al., 2003), TRPV4 (Liedtke et al., 2000; Strotmann et al., 2000), TRPC1 (Chen and Barritt, 2003), TRPC3 (Quick et al., 2012), TRPC6 (Spassova et al., 2006), TRPA1 (Corey et al., 2004; Nagata et al., 2005), TRPP2 (Nauli et al., 2003), TRPP3 (Murakami et al., 2005), TRPM3 (Grimm et al., 2003), TRPM4 (Earley et al., 2004), TRPM7 (Numata et al., 2007), and TPML3 (Di Palma et al., 2002). A full listing of mammalian TRPs involved in osmomechanosensation can be found in Table 5.1.
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analysis of trpv channel activation by stimulation of fceri and mrgpr receptors in mouse peritoneal mast cells
PLOS ONE, 2017Co-Authors: Alejandra Solislopez, Wolfgang Liedtke, Ulrich Kriebs, Alexander Marx, Stefanie Mannebach, M. J. Caterina, Marc Freichel, Volodymyr TsvilovskyyAbstract:The activation of mast cells (MC) is part of the innate and adaptive immune responses and depends on Ca2+ entry across the plasma membrane, leading to the release of preformed inflammatory mediators by degranulation or by de novo synthesis. The calcium conducting channels of the TRPV family, known by their thermo and osmotic sensitivity, have been proposed to be involved in the MC activation in murine, rat, and human mast cell models. So far, immortalized mast cell lines and nonspecific TRPV blockers have been employed to characterize the role of TRPV channels in MC. The aim of this work was to elucidate the physiological role of TRPV channels by using primary peritoneal mast cells (PMCs), a model of connective tissue type mast cells. Our RT-PCR and NanoString analysis identified the expression of TRPV1, TRPV2, and TRPV4 channels in PMCs. For determination of the functional role of the expressed TRPV channels we performed measurements of intracellular free Ca2+ concentrations and beta-hexosaminidase release in PMCs obtained from wild type and mice deficient for corresponding TRPV1, TRPV2 and TRPV4 in response to various receptor-mediated and physical stimuli. Furthermore, substances known as activators of corresponding TRPV-channels were also tested using these assays. Our results demonstrate that TRPV1, TRPV2, and TRPV4 do not participate in activation pathways triggered by activation of the high-affinity receptors for IgE (FceRI), Mrgprb2 receptor, or Endothelin-1 receptor nor by heat or osmotic stimulation in mouse PMCs.
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functional transient receptor potential vanilloid 1 and transient receptor potential vanilloid 4 channels along different segments of the renal vasculature
Acta Physiologica, 2015Co-Authors: L Chen, Mario Kasmann, Mauricio Sendeski, Dmitry Tsvetkov, Lajos Marko, Laura Michalick, Marc Riehle, Wolfgang Liedtke, Wolfgang M KueblerAbstract:AIM: Transient receptor potential vanilloid 1 (TRPV1) and vanilloid 4 (TRPV4) cation channels have been recently identified to promote endothelium-dependent relaxation of mouse mesenteric arteries. However, the role TRPV1 and TRPV4 in the renal vasculature is largely unknown. We hypothesized that TRPV1/4 play a role in endothelium-dependent vasodilation of renal blood vessels. METHODS: We studied the distribution of functional TRPV1/4 along different segments of the renal vasculature. Mesenteric arteries were studied as control vessels. RESULTS: The TRPV1 agonist capsaicin relaxed mouse mesenteric arteries with an EC50 of 25 nM, but large mouse renal arteries or rat descending vasa recta only at >100-fold higher concentrations. The vasodilatory effect of capsaicin in the low-nanomolar concentration range was endothelium-dependent and absent in vessels of Trpv1 -/- mice. The TRPV4 agonist GSK1016790A relaxed large conducting renal arteries, mesenteric arteries and vasa recta with EC50 of 18 nM, 63 nM and ~10 nM, respectively. These effects were endothelium-dependent and inhibited by a TRPV4 antagonist, AB159908 (10 muM). Capsaicin and GSK1016790A produced vascular dilation in isolated mouse perfused kidneys with EC50 of 23 nM and 3 nM, respectively. The capsaicin effects were largely reduced in Trpv1 -/- kidneys and the effects of GSK1016790A were inhibited in Trpv4 -/- kidneys. CONCLUSION: Our results demonstrate that two TRPV channels have unique sites of vasoregulatory function in the kidney with functional TRPV1 having a narrow, discrete distribution in the resistance vasculature and TRPV4 having more universal, widespread distribution along different vascular segments. We suggest that TRPV1/4 channels are potent therapeutic targets for site-specific vasodilation in the kidney.
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Role of TRPV ion channels in sensory transduction of osmotic stimuli in mammals.
Experimental physiology, 2007Co-Authors: Wolfgang LiedtkeAbstract:In signal transduction of metazoan cells, ion channels of the family of transient receptor potential (TRP) have been identified to respond to diverse external and internal stimuli, amongst them osmotic stimuli. This report highlights findings pertaining to the TRPV subfamily, focusing on mammalian members. Of the six mammalian TRPV channels, TRPV1, 2 and 4 were demonstrated to function in transduction of osmotic stimuli. TRPV channels have been found to function in cellular as well as systemic osmotic homeostasis. In a striking example of evolutionary conservation of function, mammalian TRPV4 has been found to rescue osmosensory deficits of the TRPV mutant strain osm-9 in Caenorhabditis elegans, despite not more than 26% orthology of the respective proteins.
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TRPV Channels’ Function in Osmo- and Mechanotransduction
2007Co-Authors: Wolfgang LiedtkeAbstract:In signal transduction of metazoan cells, transient receptor potential (TRP) ion channels have been identified to respond to diverse external and internal stimuli, among them osmotic and mechanical stimuli. This chapter summarizes findings on the TRPV subfamily, both its vertebrate and invertebrate members, with a focus on TRPV4. Of the six mammalian TRPV channels, TRPV1, 2, and 4 were demonstrated to function in transduction of osmotic and mechanical stimuli. Invertebrate TRPV channels, five in C. elegans and two in Drosophila, have been shown to play a role in mechanosensation, such as hearing and proprioception in Drosophila and nose touch in C. elegans, and in the response to tonicity in C. elegans. TRPV4 has been found to function in cellular as well as systemic osmotic homeostasis in vertebrates. In a striking example of evolutionary conservation of function, mammalian TRPV4 has been found to rescue mechano- and osmosensory, not olfactory, deficits of the TRPV mutant line osm-9 in C. elegans, despite not more than 25 percent orthology of the respective amino acid sequences.
Santosh Kumar - One of the best experts on this subject based on the ideXlab platform.
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transient receptor potential vanilloid 1 6 trpv1 6 gene expression in the mouse brain during estrous cycle
Brain Research, 2018Co-Authors: Omprakash Singh, Uday Singh, Praful S Singru, Chandan Goswami, Santosh KumarAbstract:In recent years estradiol has emerged as a potential regulator of transient receptor potential vanilloid (TRPV) cationic channels in the peripheral tissues and sensory neurons, however, its analogous role in the CNS is poorly understood. TRPV channels modulate Ca2+ signalling, neurotransmission and behaviour, and expression of these ion channels and estrogen receptors show a great degree of overlap in different brain regions. Herein, we probe if Trpv1-6 genes contain estrogen receptor-binding sites and if their expression in different brain regions is modulated during estrous cycle. Bioinformatics analysis of the mouse Trpv1-6 gene sequences showed presence of putative functional estrogen response element in their promoter regions. Using qRT-PCR, Trpv1-6 mRNA expression was observed in the olfactory bulb, cortex, hypothalamus, hippocampus, brainstem, and cerebellum of mouse. In these regions, compared to estrus, metestrus, and diestrus, reduced levels of Trpv1 and TRPV5 but elevated Trpv2 and Trpv6 mRNA levels were observed during proestrus. Lower levels of Trpv3 and Trpv4 mRNAs were seen during estrus but higher expression of Trpv3 during metestrus and diestrus, and Trpv4 during proestrus was observed. Estradiol seems to regulate Trpv1/TRPV5 and Trpv2/Trpv6 mRNA expression in opposite manner. Except Trpv4 mRNA expression in the hippocampus and Trpv6 expression in the olfactory bulb, hippocampus and brainstem, expression of other members of TRPV subfamily in distinct brain regions of male mice was comparable to those in metestrus and diestrus mice. We suggest that the circulating levels of estradiol during the estrous cycle may differentially regulate the activity of TRPV1-6 ion channels in the brain.
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transient receptor potential vanilloid 5 TRPV5 a highly ca2 selective trp channel in the rat brain relevance to neuroendocrine regulation
Journal of Neuroendocrinology, 2017Co-Authors: Uday Singh, Praful S Singru, Chandan Goswami, Santosh KumarAbstract:Recent studies suggest an important role for transient receptor potential vanilloid (TRPV) ion channels in neural and neuroendocrine regulation. The TRPV subfamily consists of six members: TRPV1-6. While the neuroanatomical and functional correlates of TRPV1-4 have been studied extensively, relevant information about TRPV5 and TRPV6, which are highly selective for Ca2+ , is limited. We detected TRPV5 mRNA expression in the olfactory bulb, cortex, hypothalamus, hippocampus, midbrain, brainstem and cerebellum of the rat. TRPV5-immunoreactive neurones were conspicuously seen in the hypothalamic paraventricular (PVN), supraoptic (SON), accessory neurosecretory (ANS), supraoptic nucleus, retrochiasmatic part (SOR), arcuate (ARC) and medial tuberal nuclei, hippocampus, midbrain, brainstem and cerebellum. Glial cells also showed TRPV5-immunoreactivity. To test the neuroendocrine relevance of TRPV5, we focused on vasopressin, oxytocin and cocaine- and amphetamine-regulated transcript (CART) as representative candidate markers with which TRPV5 may co-exist. In the hypothalamic neurones, co-expression of TRPV5 was observed with vasopressin (PVN: 50.73±3.82%; SON: 75.91±2.34%; ANS: 49.12±4.28%; SOR: 100%) and oxytocin (PVN: 6.88±1.21; SON: 63.34±5.69%; ANS: 20.4±4.14; SOR: 86.5±1.74%). While ARC neurones express oestrogen receptors, 17β-oestradiol regulates TRPV5, as well as CART neurones and astrocytes, in the ARC. Furthermore, ARC CART neurones are known to project to the preoptic area, and innervate and regulate GnRH neurones. Using double-immunofluorescence, glial fibrillary acidic protein-labelled astrocytes and the majority of CART neurones in the ARC showed TRPV5-immunoreactivity. Following iontophoresis of retrograde neuronal tracer, cholera toxin β (CtB) into the anteroventral periventricular nucleus and median preoptic nucleus, retrograde accumulation of CtB was observed in most TRPV5-equipped ARC CART neurones. Next, we determined the response of TRPV5-elements in the ARC during the oestrous cycle. Compared to pro-oestrus, a significant increase (P<.001) in the percentage of TRPV5-expressing CART neurones was observed during oestrus, metoestrus, and dioestrus. TRPV5-immunoreactivity in the astrocytes, however, showed a significant increase during metoestrus and dioestrus. We suggest that the TRPV5 ion channel may serve as an important regulator of neural and neuroendocrine pathways in the brain.
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transient receptor potential vanilloid 6 trpv6 in the mouse brain distribution and estrous cycle related changes in the hypothalamus
Neuroscience, 2017Co-Authors: Omprakash Singh, Uday Singh, Praful S Singru, Chandan Goswami, Santosh KumarAbstract:Transient receptor potential vanilloid (TRPV) subfamily of cationic channels have emerged as novel players in neural regulation. Unlike other members of TRPV subfamily, TRPV5 and TRPV6 are highly Ca2+-selective. Although TRPV5/TRPV6 transcripts are expressed in mouse brain, understanding the full functional spectrum of these ion channels in the brain is however limited due to the lack of information on their neuroanatomical distribution. We have studied TRPV6 in mouse brain in further detail. In the hypothalamus, while Western blot analysis using TRPV6 specific antiserum showed a distinct ∼95 kDa band corresponding to the molecular weight of TRPV6, transcripts for TRPV6 were detected with RT-PCR. TRPV6-immunoreactive cells/fibers were observed in vascular organ of the lamina terminalis, olfactory bulb, amygdala, hippocampus, septohypothalamic, supraoptic, arcuate (ARC), dorsomedial, and subincertal nuclei. TRPV6-immunoreactive cells/fibers were also observed in the brainstem and cerebellum. Estrogen has emerged as a potential regulator of TRPV6 in peripheral tissues. TRPV6 gene promoter contains estrogen-response element, estrogen activates TRPV6 via estrogen receptor alpha (ERα), and ERα-expressing ARC neurons in mediobasal hypothalamus (MBH) serve as primary site for estradiol feedback. Using double immunofluorescence, co-expression of TRPV6 and ERα was observed in several ARC neurons. MBH of mice during different phases of estrous cycle were subjected to Western blot analysis of TRPV6. Compared to proestrus, a significant reduction (P < 0.01) in intensity of TRPV6-immunoreactive band was observed in MBH during metestrus and diestrus phases. While the wide distribution of TRPV6-expressing elements in the brain suggests its role in a range of CNS functions, the ion channel may serve as novel component of the neural pathway mediating effects of estradiol in MBH.