The Experts below are selected from a list of 21180 Experts worldwide ranked by ideXlab platform
Rachelle Gaudet - One of the best experts on this subject based on the ideXlab platform.
-
what do we know about the transient receptor potential vanilloid 2 trpv2 ion channel
FEBS Journal, 2013Co-Authors: Alex Peralvarezmarin, Pau Donatemacian, Rachelle GaudetAbstract:Transient receptor potential (TRP) ion channels are emerging as a new set of membrane proteins involved in a vast array of cellular processes and regulated by a large number of physical and chemical stimuli, which involves them with sensory cell physiology. The vanilloid TRP subfamily (TRPV) named after the vanilloid receptor 1 (TRPV1) consists of six members, and at least four of them (TRPV1-TRPV4) have been related to thermal sensation. One of the least characterized members of the TRP subfamily is TRPV2. Although initially characterized as a noxious heat sensor, TRPV2 now seems to have little to do with temperature sensing, but a much more complex physiological profile. Here we review the available information and research progress on the structure, physiology and pharmacology of TRPV2 in an attempt to shed some light on the physiological and pharmacological deorphanization of TRPV2.
-
differential regulation of trpv1 trpv3 and TRPV4 sensitivity through a conserved binding site on the ankyrin repeat domain
Journal of Biological Chemistry, 2010Co-Authors: Christopher B Phelps, Ruiqi Rachel Wang, Shelly Seungah Choo, Rachelle GaudetAbstract:Transient receptor potential vanilloid (TRPV) channels, which include the thermosensitive TRPV1–V4, have large cytoplasmic regions flanking the transmembrane domain, including an N-terminal ankyrin repeat domain. We show that a multiligand binding site for ATP and calmodulin previously identified in the TRPV1 ankyrin repeat domain is conserved in TRPV3 and TRPV4, but not TRPV2. Accordingly, TRPV2 is insensitive to intracellular ATP, while, as previously observed with TRPV1, a sensitizing effect of ATP on TRPV4 required an intact binding site. In contrast, ATP reduced TRPV3 sensitivity and potentiation by repeated agonist stimulations. Thus, ATP and calmodulin, acting through this conserved binding site, are key players in generating the different sensitivity and adaptation profiles of TRPV1, TRPV3, and TRPV4. Our results suggest that competing interactions of ATP and calmodulin influence channel sensitivity to fluctuations in calcium concentration and perhaps even metabolic state. Different feedback mechanisms likely arose because of the different physiological stimuli or temperature thresholds of these channels.
-
structural analyses of the ankyrin repeat domain of trpv6 and related trpv ion channels
Biochemistry, 2008Co-Authors: Christopher B Phelps, Ruiqi Rachel Wang, Robert J. Huang, Polina V Lishko, Rachelle GaudetAbstract:Transient Receptor Potential (TRP) proteins are cation channels composed of a transmembrane domain flanked by large N- and C-terminal cytoplasmic domains. All members of the vanilloid family of TRP channels (TRPV) possess an N-terminal ankyrin repeat domain (ARD). The ARD of mammalian TRPV6, an important regulator of calcium uptake and homeostasis, is essential for channel assembly and regulation. The 1.7 A crystal structure of the TRPV6-ARD reveals conserved structural elements unique to the ARDs of TRPV proteins. First, a large twist between the fourth and fifth repeats is induced by residues conserved in all TRPV ARDs. Second, the third finger loop is the most variable region in sequence, length and conformation. In TRPV6, a number of putative regulatory phosphorylation sites map to the base of this third finger. Size exclusion chromatography and crystal packing indicate that the TRPV6-ARD does not assemble as a tetramer and is monomeric in solution. Adenosine triphosphate-agarose and calmodulin-agarose pull-down assays show that the TRPV6-ARD does not interact with either ligand, indicating a different functional role for the TRPV6-ARD than in the paralogous thermosensitive TRPV1 channel. Similar biochemical findings are also presented for the highly homologous mammalian TRPV5-ARD. The implications of the structural and biochemical data on the role of the ankyrin repeats in different TRPV channels are discussed. The Transient Receptor Potential (TRP) proteins are a superfamily of cation channels with diverse functions. All TRP channels share a similar six-transmembrane-segment iontransport domain flanked by intracellular N- and C-terminal domains, and are expected to function as tetramers. TRP channels are divided into seven subfamilies based on sequence similarity in their cytosolic domains, (TRPA – ANKTM1, TRPC – canonical, TRPM – melastatin, TRPN – NOMP-C, TRPV – vanilloid receptor, and the more distantly related
-
structural analyses of the ankyrin repeat domain of trpv6 and related trpv ion channels
Biochemistry, 2008Co-Authors: Christopher B Phelps, Ruiqi Rachel Wang, Robert J. Huang, Polina V Lishko, Rachelle GaudetAbstract:Transient receptor potential (TRP) proteins are cation channels composed of a transmembrane domain flanked by large N- and C-terminal cytoplasmic domains. All members of the vanilloid family of TRP channels (TRPV) possess an N-terminal ankyrin repeat domain (ARD). The ARD of mammalian TRPV6, an important regulator of calcium uptake and homeostasis, is essential for channel assembly and regulation. The 1.7 A crystal structure of the TRPV6-ARD reveals conserved structural elements unique to the ARDs of TRPV proteins. First, a large twist between the fourth and fifth repeats is induced by residues conserved in all TRPV ARDs. Second, the third finger loop is the most variable region in sequence, length and conformation. In TRPV6, a number of putative regulatory phosphorylation sites map to the base of this third finger. Size exclusion chromatography and crystal packing indicate that the TRPV6-ARD does not assemble as a tetramer and is monomeric in solution. Adenosine triphosphate-agarose and calmodulin-agarose pull-down assays show that the TRPV6-ARD does not interact with either ligand, indicating a different functional role for the TRPV6-ARD than in the paralogous thermosensitive TRPV1 channel. Similar biochemical findings are also presented for the highly homologous mammalian TRPV5-ARD. The implications of the structural and biochemical data on the role of the ankyrin repeats in different TRPV channels are discussed.
Wolfgang Liedtke - One of the best experts on this subject based on the ideXlab platform.
-
TRPV4 Mediates Hypotonic Inhibition of Central Osmosensory Neurons via Taurine Gliotransmission
Elsevier, 2018Co-Authors: Sorana Ciura, Wolfgang Liedtke, Masha Prager-khoutorsky, Zahra S. Thirouin, Joshua C. Wyrosdic, James E. Olson, Charles W. BourqueAbstract:Summary: The maintenance of hydromineral homeostasis requires bidirectional detection of changes in extracellular fluid osmolality by primary osmosensory neurons (ONs) in the organum vasculosum laminae terminalis (OVLT). Hypertonicity excites ONs in part through the mechanical activation of a variant transient receptor potential vanilloid-1 channel (dn-Trpv1). However, the mechanism by which local hypotonicity inhibits ONs in the OVLT remains unknown. Here, we show that hypotonicity can reduce the basal activity of dn-Trpv1 channels and hyperpolarize acutely isolated ONs. Surprisingly, we found that mice lacking dn-Trpv1 maintain normal inhibitory responses to hypotonicity when tested in situ. In the intact setting, hypotonicity inhibits ONs through a non-cell-autonomous mechanism that involves glial release of the glycine receptor agonist taurine through hypotonicity activated anion channels (HAAC) that are activated subsequent to Ca2+ influx through TRPV4 channels. Our study clarifies how TRPV4 channels contribute to the inhibition of OVLT ONs during hypotonicity in situ. : Ciura et al. show that osmosensory neurons in organum vasculosum lamina terminalis are inhibited by hypotonicity. This effect is triggered by activation of TRPV4 channels and Ca2+ accumulation in astrocytes, causing these cells to release taurine through anion channels. Taurine inhibits firing by activating glycine receptors on the osmosensory neurons. Keywords: hyptonicity, taurine, TRPV, osmosensitive, gliotransmission, swellin
-
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.
-
analysis of trpv channel activation by stimulation of fceri and mrgpr receptors in mouse peritoneal mast cells
PLOS ONE, 2017Co-Authors: Alejandra Solislopez, Marc Freichel, Wolfgang Liedtke, Ulrich Kriebs, Alexander Marx, Stefanie Mannebach, M. J. Caterina, 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.
-
p2y1 receptor activation of the TRPV4 ion channel enhances purinergic signaling in satellite glial cells
Journal of Biological Chemistry, 2015Co-Authors: Pradeep Rajasekhar, Wolfgang Liedtke, Daniel P Poole, Nigel W Bunnett, Nicholas A VeldhuisAbstract:Transient receptor potential (TRP) ion channels of peripheral sensory pathways are important mediators of pain, itch, and neurogenic inflammation. They are expressed by primary sensory neurons and by glial cells in the central nervous system, but their expression and function in satellite glial cells (SGCs) of sensory ganglia have not been explored. SGCs tightly ensheath neurons of sensory ganglia and can regulate neuronal excitability in pain and inflammatory states. Using a modified dissociation protocol, we isolated neurons with attached SGCs from dorsal root ganglia of mice. SGCs, which were identified by expression of immunoreactive Kir4.1 and glutamine synthetase, were closely associated with neurons, identified using the pan-neuronal marker NeuN. A subpopulation of SGCs expressed immunoreactive TRP vanilloid 4 (TRPV4) and responded to the TRPV4-selective agonist GSK1016790A by an influx of Ca(2+) ions. SGCs did not express functional TRPV1, TRPV3, or TRP ankyrin 1 channels. Responses to GSK1016790A were abolished by the TRPV4 antagonist HC067047 and were absent in SGCs from TRPV4(-/-) mice. The P2Y1-selective agonist 2-methylthio-ADP increased [Ca(2+)]i in SGCs, and responses were prevented by the P2Y1-selective antagonist MRS2500. P2Y1 receptor-mediated responses were enhanced in TRPV4-expressing SGCs and HEK293 cells, suggesting that P2Y1 couples to and activates TRPV4. PKC inhibitors prevented P2Y1 receptor activation of TRPV4. Our results provide the first evidence for expression of TRPV4 in SGCs and demonstrate that TRPV4 is a purinergic receptor-operated channel in SGCs of sensory ganglia.
-
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.
Praful S Singru - One of the best experts on this subject based on the ideXlab platform.
-
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.
-
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.
-
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.
Joost G J Hoenderop - One of the best experts on this subject based on the ideXlab platform.
-
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.
-
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.
-
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.
Santosh Kumar - One of the best experts on this subject based on the ideXlab platform.
-
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.
-
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.
-
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.
