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Neuberger A, Sobolevsky AI. Molecular pharmacology of the onco-TRP channel TRPV6. Channels (Austin) 2023; 17:2266669. [PMID: 37838981 PMCID: PMC10578198 DOI: 10.1080/19336950.2023.2266669] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2023] [Accepted: 09/29/2023] [Indexed: 10/17/2023] Open
Abstract
TRPV6, a representative of the vanilloid subfamily of TRP channels, serves as the principal calcium uptake channel in the gut. Dysregulation of TRPV6 results in disturbed calcium homeostasis leading to a variety of human diseases, including many forms of cancer. Inhibitors of this oncochannel are therefore particularly needed. In this review, we provide an overview of recent advances in structural pharmacology that uncovered the molecular mechanisms of TRPV6 inhibition by a variety of small molecules, including synthetic and natural, plant-derived compounds as well as some prospective and clinically approved drugs.
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Affiliation(s)
- Arthur Neuberger
- Department of Biochemistry and Molecular Biophysics, Columbia University, New York, NY, USA
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2
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Luo ZH, Ma JX, Zhang W, Tian AX, Gong SW, Li Y, Lai YX, Ma XL. Alterations in the microenvironment and the effects produced of TRPV5 in osteoporosis. J Transl Med 2023; 21:327. [PMID: 37198647 DOI: 10.1186/s12967-023-04182-8] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/01/2022] [Accepted: 05/05/2023] [Indexed: 05/19/2023] Open
Abstract
The pathogenesis of osteoporosis involves multiple factors, among which alterations in the bone microenvironment play a crucial role in disrupting normal bone metabolic balance. Transient receptor potential vanilloid 5 (TRPV5), a member of the TRPV family, is an essential determinant of the bone microenvironment, acting at multiple levels to influence its properties. TRPV5 exerts a pivotal influence on bone through the regulation of calcium reabsorption and transportation while also responding to steroid hormones and agonists. Although the metabolic consequences of osteoporosis, such as loss of bone calcium, reduced mineralization capacity, and active osteoclasts, have received significant attention, this review focuses on the changes in the osteoporotic microenvironment and the specific effects of TRPV5 at various levels.
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Affiliation(s)
- Zhi-Heng Luo
- Tianjin Hospital, Tianjin University, Jie Fang Nan Road 406, Tianjin, 300211, People's Republic of China
- Tianjin Key Laboratory of Orthopedic Biomechanics and Medical Engineering, Tianjin Hospital, Tianjin, 300050, People's Republic of China
| | - Jian-Xiong Ma
- Tianjin Hospital, Tianjin University, Jie Fang Nan Road 406, Tianjin, 300211, People's Republic of China
- Tianjin Key Laboratory of Orthopedic Biomechanics and Medical Engineering, Tianjin Hospital, Tianjin, 300050, People's Republic of China
| | - Wei Zhang
- Centre for Translational Medicine Research & Development, Shenzhen Institutes of Advanced Technology, Chinese Academy of Sciences, 1068 Xue Yuan Avenue, Shenzhen University Town, Shenzhen, 518055, Guangdong, People's Republic of China
| | - Ai-Xian Tian
- Tianjin Hospital, Tianjin University, Jie Fang Nan Road 406, Tianjin, 300211, People's Republic of China
- Tianjin Key Laboratory of Orthopedic Biomechanics and Medical Engineering, Tianjin Hospital, Tianjin, 300050, People's Republic of China
| | - Shu-Wei Gong
- Tianjin Hospital, Tianjin University, Jie Fang Nan Road 406, Tianjin, 300211, People's Republic of China
- Tianjin Key Laboratory of Orthopedic Biomechanics and Medical Engineering, Tianjin Hospital, Tianjin, 300050, People's Republic of China
| | - Yan Li
- Tianjin Hospital, Tianjin University, Jie Fang Nan Road 406, Tianjin, 300211, People's Republic of China
- Tianjin Key Laboratory of Orthopedic Biomechanics and Medical Engineering, Tianjin Hospital, Tianjin, 300050, People's Republic of China
| | - Yu-Xiao Lai
- Centre for Translational Medicine Research & Development, Shenzhen Institutes of Advanced Technology, Chinese Academy of Sciences, 1068 Xue Yuan Avenue, Shenzhen University Town, Shenzhen, 518055, Guangdong, People's Republic of China.
| | - Xin-Long Ma
- Tianjin Hospital, Tianjin University, Jie Fang Nan Road 406, Tianjin, 300211, People's Republic of China.
- Tianjin Key Laboratory of Orthopedic Biomechanics and Medical Engineering, Tianjin Hospital, Tianjin, 300050, People's Republic of China.
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3
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Ott D, Manneck D, Schrapers KT, Rosendahl J, Aschenbach JR. Blood calcium concentration and performance in periparturient and early lactating dairy cows is influenced by plant bioactive lipid compounds. J Dairy Sci 2023; 106:3706-3718. [PMID: 36907757 DOI: 10.3168/jds.2022-22387] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/07/2022] [Accepted: 11/22/2022] [Indexed: 03/14/2023]
Abstract
Previous studies ex vivo suggested that plant bioactive lipid compounds (PBLC) can increase ruminal calcium absorption. Therefore, we hypothesized that PBLC feeding around calving may potentially counteract hypocalcemia and support performance in postpartum dairy cows. The corresponding aim of the study was to investigate the effect of PBLC feeding on blood minerals in Brown Swiss (BS) and hypocalcemia-susceptible Holstein Friesian (HF) cows during the period from d -2 to 28 relative to calving and on milk performance until d 80 of lactation. A total of 29 BS cows and 41 HF cows were divided each into a control (CON) and PBLC treatment group. The latter was supplemented with 1.7 g/d menthol-rich PBLC from 8 d before expected calving to 80 d postpartum. Milk yield and composition, body condition score and blood minerals were measured. Feeding PBLC induced a significant breed × treatment interaction for iCa, supporting that PBLC increased iCa exclusively in HF cows; the increase was 0.03 mM over the whole period and 0.05 mM from d 1 to 3 after calving. Subclinical hypocalcemia was seen in one BS-CON and 8 HF-CON cows and 2 BS-PBLC and 4 HF-PBLC cows. Clinical milk fever was detected only in HF cows (2 HF-CON and one HF-PBLC). Other tested blood minerals, such as sodium, chloride, and potassium, as well as blood glucose, were neither affected by PBLC feeding nor breed, nor were their 2-way interactions, except for higher sodium levels in PBLC cows on d 21. Body condition score showed no effect of treatment, except for a lower body condition score in BS-PBLC compared with BS-CON at d 14. Dietary PBLC increased milk yield, milk fat yield, and milk protein yield at 2 consecutive dairy herd improvement test days. As indicated by treatment × day interactions, energy-corrected milk yield and milk lactose yield were increased by PBLC on the first test day only, and milk protein concentration decreased from test d 1 to test d 2 in CON only. The concentrations of fat, lactose, and urea, as well as somatic cell count, were not affected by treatment. The weekly milk yield over the first 11 wk of lactation was 29.5 kg/wk higher for PBLC versus CON across breeds. It is concluded that the applied PBLC induced a small but measurable improvement of calcium status in HF cows in the study period and had additional positive effects on milk performance in both breeds.
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Affiliation(s)
- D Ott
- Institute of Veterinary Physiology, Freie Universität Berlin, D-14163 Berlin, Germany; PerformaNat GmbH, D-14163 Berlin, Germany
| | - D Manneck
- PerformaNat GmbH, D-14163 Berlin, Germany
| | | | | | - J R Aschenbach
- Institute of Veterinary Physiology, Freie Universität Berlin, D-14163 Berlin, Germany.
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4
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Intracellular Helix-Loop-Helix Domain Modulates Inactivation Kinetics of Mammalian TRPV5 and TRPV6 Channels. Int J Mol Sci 2023; 24:ijms24054470. [PMID: 36901904 PMCID: PMC10003196 DOI: 10.3390/ijms24054470] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/17/2022] [Revised: 02/10/2023] [Accepted: 02/17/2023] [Indexed: 03/12/2023] Open
Abstract
TRPV5 and TRPV6 are calcium-selective ion channels expressed at the apical membrane of epithelial cells. Important for systemic calcium (Ca2+) homeostasis, these channels are considered gatekeepers of this cation transcellular transport. Intracellular Ca2+ exerts a negative control over the activity of these channels by promoting inactivation. TRPV5 and TRPV6 inactivation has been divided into fast and slow phases based on their kinetics. While slow inactivation is common to both channels, fast inactivation is characteristic of TRPV6. It has been proposed that the fast phase depends on Ca2+ binding and that the slow phase depends on the binding of the Ca2+/Calmodulin complex to the internal gate of the channels. Here, by means of structural analyses, site-directed mutagenesis, electrophysiology, and molecular dynamic simulations, we identified a specific set of amino acids and interactions that determine the inactivation kinetics of mammalian TRPV5 and TRPV6 channels. We propose that the association between the intracellular helix-loop-helix (HLH) domain and the TRP domain helix (TDh) favors the faster inactivation kinetics observed in mammalian TRPV6 channels.
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5
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Walker V, Vuister GW. Biochemistry and pathophysiology of the Transient Potential Receptor Vanilloid 6 (TRPV6) calcium channel. Adv Clin Chem 2023; 113:43-100. [PMID: 36858649 DOI: 10.1016/bs.acc.2022.11.002] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/15/2023]
Abstract
TRPV6 is a Transient Receptor Potential Vanilloid (TRPV) cation channel with high selectivity for Ca2+ ions. First identified in 1999 in a search for the gene which mediates intestinal Ca2+ absorption, its far more extensive repertoire as a guardian of intracellular Ca2+ has since become apparent. Studies on TRPV6-deficient mice demonstrated additional important roles in placental Ca2+ transport, fetal bone development and male fertility. The first reports of inherited deficiency in newborn babies appeared in 2018, revealing its physiological importance in humans. There is currently strong evidence that TRPV6 also contributes to the pathogenesis of some common cancers. The recently reported association of TRPV6 deficiency with non-alcoholic chronic pancreatitis suggests a role in normal pancreatic function. Over time and with greater awareness of TRPV6, other disease-associations are likely to emerge. Powerful analytical tools have provided invaluable insights into the structure and operation of TRPV6. Its roles in Ca2+ signaling and carcinogenesis, and the use of channel inhibitors in cancer treatment are being intensively investigated. This review first briefly describes the biochemistry and physiology of the channel, and analytical methods used to investigate these. The focus subsequently shifts to the clinical disorders associated with abnormal expression and the underlying pathophysiology. The aims of this review are to increase awareness of this channel, and to draw together findings from a wide range of sources which may help to formulate new ideas for further studies.
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Affiliation(s)
- Valerie Walker
- Department of Clinical Biochemistry, University Hospital Southampton NHS Foundation Trust, Southampton General Hospital, Southampton, United Kingdom.
| | - Geerten W Vuister
- Department of Molecular and Cell Biology, Leicester Institute of Structural and Chemical Biology, University of Leicester, Leicester, United Kingdom
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6
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Cantero MDR, Cantiello HF. Polycystin-2 (TRPP2): Ion channel properties and regulation. Gene 2022; 827:146313. [PMID: 35314260 DOI: 10.1016/j.gene.2022.146313] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/09/2021] [Revised: 01/19/2022] [Accepted: 02/08/2022] [Indexed: 12/01/2022]
Abstract
Polycystin-2 (TRPP2, PKD2, PC2) is the product of the PKD2 gene, whose mutations cause Autosomal Dominant Polycystic Kidney Disease (ADPKD). PC2 belongs to the superfamily of TRP (Transient Receptor Potential) proteins that generally function as Ca2+-permeable nonselective cation channels implicated in Ca2+ signaling. PC2 localizes to various cell domains with distinct functions that likely depend on interactions with specific channel partners. Functions include receptor-operated, nonselective cation channel activity in the plasma membrane, intracellular Ca2+ release channel activity in the endoplasmic reticulum (ER), and mechanosensitive channel activity in the primary cilium of renal epithelial cells. Here we summarize our current understanding of the properties of PC2 and how other transmembrane and cytosolic proteins modulate this activity, providing functional diversity and selective regulatory mechanisms to its role in the control of cellular Ca2+ homeostasis.
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Affiliation(s)
- María Del Rocío Cantero
- Laboratorio de Canales Iónicos, Instituto Multidisciplinario de Salud, Tecnología y Desarrollo (IMSaTeD, CONICET-UNSE), El Zanjón, Santiago del Estero 4206, Argentina.
| | - Horacio F Cantiello
- Laboratorio de Canales Iónicos, Instituto Multidisciplinario de Salud, Tecnología y Desarrollo (IMSaTeD, CONICET-UNSE), El Zanjón, Santiago del Estero 4206, Argentina
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7
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TRPV6 Regulation by Cis-22a and Cholesterol. Biomolecules 2022; 12:biom12060804. [PMID: 35740929 PMCID: PMC9221249 DOI: 10.3390/biom12060804] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/23/2022] [Revised: 06/03/2022] [Accepted: 06/05/2022] [Indexed: 02/04/2023] Open
Abstract
The highly calcium-selective transient receptor potential vanilloid-type channel TRPV6 is important for epithelial Ca2+ transport. Proper regulation of the inherently constitutively active TRPV6 channels is intricate in preserving Ca2+ homeostasis, whereby structural and functional data suggest that lipids hold an essential role. Altered expression levels or specific TRPV6 mutations may lead to diseases, hence, TRPV6 represents an interesting target for pharmacological modulation. Recent cryo-EM data identified that the specific TRPV6 blocker cis-22a binds, apart from the pore, to a site within the tetrameric channel that largely matches a lipid binding pocket, LBS-2. Therein, cis-22a may replace a lipid such as cholesterol that is bound in the open state. Based on site-directed mutagenesis and functional recordings, we identified and characterized a series of residues within LBS-2 that are essential for TRPV6 inhibition by cis-22a. Additionally, we investigated the modulatory potential of diverse cholesterol depletion efforts on TRPV6 activity. While LBS-2 mutants exhibited altered maximum currents, slow Ca2+-dependent inactivation (SCDI) as well as less inhibition by cis-22a, TRPV6 activity was resistant to cholesterol depletion. Hence, lipids other than cholesterol may predominate TRPV6 regulation when the channel is expressed in HEK293 cells.
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8
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Khattar V, Wang L, Peng JB. Calcium selective channel TRPV6: Structure, function, and implications in health and disease. Gene 2022; 817:146192. [PMID: 35031425 PMCID: PMC8950124 DOI: 10.1016/j.gene.2022.146192] [Citation(s) in RCA: 22] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2020] [Revised: 12/20/2021] [Accepted: 01/07/2022] [Indexed: 12/14/2022]
Abstract
Calcium-selective channel TRPV6 (Transient Receptor Potential channel family, Vanilloid subfamily member 6) belongs to the TRP family of cation channels and plays critical roles in transcellular calcium (Ca2+) transport, reuptake of Ca2+ into cells, and maintaining a local low Ca2+ environment for certain biological processes. Recent crystal and cryo-electron microscopy-based structures of TRPV6 have revealed mechanistic insights on how the protein achieves Ca2+ selectivity, permeation, and inactivation by calmodulin. The TRPV6 protein is expressed in a range of epithelial tissues such as the intestine, kidney, placenta, epididymis, and exocrine glands such as the pancreas, prostate and salivary, sweat, and mammary glands. The TRPV6 gene is a direct transcriptional target of the active form of vitamin D and is efficiently regulated to meet the body's need for Ca2+ demand. In addition, TRPV6 is also regulated by the level of dietary Ca2+ and under physiological conditions such as pregnancy and lactation. Genetic models of loss of function in TRPV6 display hypercalciuria, decreased bone marrow density, deficient weight gain, reduced fertility, and in some cases alopecia. The models also reveal that the channel plays an indispensable role in maintaining maternal-fetal Ca2+ transport and low Ca2+ environment in the epididymal lumen that is critical for male fertility. Most recently, loss of function mutations in TRPV6 gene is linked to transient neonatal hyperparathyroidism and early onset chronic pancreatitis. TRPV6 is overexpressed in a wide range of human malignancies and its upregulation is strongly correlated to tumor aggressiveness, metastasis, and poor survival in selected cancers. This review summarizes the current state of knowledge on the expression, structure, biophysical properties, function, polymorphisms, and regulation of TRPV6. The aberrant expression, polymorphisms, and dysfunction of this protein linked to human diseases are also discussed.
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Affiliation(s)
- Vinayak Khattar
- Division of Nephrology, Department of Medicine, Nephrology Research and Training Center, Department of Urology, University of Alabama at Birmingham, Birmingham, AL 35294, USA
| | - Lingyun Wang
- Division of Nephrology, Department of Medicine, Nephrology Research and Training Center, Department of Urology, University of Alabama at Birmingham, Birmingham, AL 35294, USA
| | - Ji-Bin Peng
- Division of Nephrology, Department of Medicine, Nephrology Research and Training Center, Department of Urology, University of Alabama at Birmingham, Birmingham, AL 35294, USA.
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9
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Humer C, Romanin C, Höglinger C. Highlighting the Multifaceted Role of Orai1 N-Terminal- and Loop Regions for Proper CRAC Channel Functions. Cells 2022; 11:371. [PMID: 35159181 PMCID: PMC8834118 DOI: 10.3390/cells11030371] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/23/2021] [Revised: 01/14/2022] [Accepted: 01/15/2022] [Indexed: 11/16/2022] Open
Abstract
Orai1, the Ca2+-selective pore in the plasma membrane, is one of the key components of the Ca2+release-activated Ca2+ (CRAC) channel complex. Activated by the Ca2+ sensor in the endoplasmic reticulum (ER) membrane, stromal interaction molecule 1 (STIM1), via direct interaction when ER luminal Ca2+ levels recede, Orai1 helps to maintain Ca2+ homeostasis within a cell. It has already been proven that the C-terminus of Orai1 is indispensable for channel activation. However, there is strong evidence that for CRAC channels to function properly and maintain all typical hallmarks, such as selectivity and reversal potential, additional parts of Orai1 are needed. In this review, we focus on these sites apart from the C-terminus; namely, the second loop and N-terminus of Orai1 and on their multifaceted role in the functioning of CRAC channels.
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Affiliation(s)
| | | | - Carmen Höglinger
- Institute of Biophysics, Johannes Kepler University Linz, Gruberstrasse 40, 4020 Linz, Austria; (C.H.); (C.R.)
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10
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Structural mechanisms of TRPV6 inhibition by ruthenium red and econazole. Nat Commun 2021; 12:6284. [PMID: 34725357 PMCID: PMC8560856 DOI: 10.1038/s41467-021-26608-x] [Citation(s) in RCA: 31] [Impact Index Per Article: 10.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/22/2021] [Accepted: 10/14/2021] [Indexed: 11/26/2022] Open
Abstract
TRPV6 is a calcium-selective ion channel implicated in epithelial Ca2+ uptake. TRPV6 inhibitors are needed for the treatment of a broad range of diseases associated with disturbed calcium homeostasis, including cancers. Here we combine cryo-EM, calcium imaging, and mutagenesis to explore molecular bases of human TRPV6 inhibition by the antifungal drug econazole and the universal ion channel blocker ruthenium red (RR). Econazole binds to an allosteric site at the channel’s periphery, where it replaces a lipid. In contrast, RR inhibits TRPV6 by binding in the middle of the ion channel’s selectivity filter and plugging its pore like a bottle cork. Despite different binding site locations, both inhibitors induce similar conformational changes in the channel resulting in closure of the gate formed by S6 helices bundle crossing. The uncovered molecular mechanisms of TRPV6 inhibition can guide the design of a new generation of clinically useful inhibitors. TRPV6 is a calcium-selective ion channel that is involved in numerous calcium-dependent physiological processes and it is of interest as a potential drug target. Here, the authors present the cryo-EM structures of human TRPV6 with the bound inhibitors ruthenium red and the antifungal drug econazole and discuss their inhibition mechanisms.
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Nett V, Erhardt N, Wyatt A, Wissenbach U. Human TRPV6-pathies caused by gene mutations. Biochim Biophys Acta Gen Subj 2021; 1865:129873. [PMID: 33610740 DOI: 10.1016/j.bbagen.2021.129873] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/16/2020] [Revised: 02/11/2021] [Accepted: 02/11/2021] [Indexed: 12/22/2022]
Abstract
The TRP-family of ion channels consists of 27 members in humans. Most TRP channels are non- selective cation channels with the exception of TRPV5 and TRPV6 which exhibit a high permeability for Ca2+ ions. A functional channel is formed by 4 identical subunits [1]. A growing number of mutations are present in human TRPV6 genes which alter channel function and can lead to elevated blood levels of the parathyroid hormone accompanied by transient hyperparathyroidism. Recent publications suggest that TRPV6 mutations could also trigger non-alcoholic chronic pancreatitis. This review summarises the consequences of these mutations within the TRPV6 gene.
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Affiliation(s)
- Verena Nett
- Institut für Experimentelle und Klinische Pharmakologie und Toxikologie, Universität des Saarlandes, 66421 Homburg, Germany.
| | - Nicole Erhardt
- Institut für Experimentelle und Klinische Pharmakologie und Toxikologie, Universität des Saarlandes, 66421 Homburg, Germany.
| | - Amanda Wyatt
- Institut für Experimentelle und Klinische Pharmakologie und Toxikologie, Universität des Saarlandes, 66421 Homburg, Germany.
| | - Ulrich Wissenbach
- Institut für Experimentelle und Klinische Pharmakologie und Toxikologie, Universität des Saarlandes, 66421 Homburg, Germany.
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12
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Brauchi SE, Rothberg BS. Gating and calcium-sensing mechanisms of TRPA1 channels revealed. Cell Calcium 2020; 91:102278. [PMID: 32858446 DOI: 10.1016/j.ceca.2020.102278] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/17/2020] [Revised: 08/18/2020] [Accepted: 08/18/2020] [Indexed: 11/30/2022]
Abstract
Novel structures of the human TRPA1 channel were determined in the presence of the agonist iodoacetamide and the antagonist A-967079, to reveal the open and closed states of the channel, respectively. The structures further revealed the location of Ca2+ modulatory site that is likely conserved among several TRP subgroups.
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Affiliation(s)
- Sebastian E Brauchi
- Instituto de Fisiología, Facultad de Medicina, Universidad Austral de Chile, and Millennium Nucleus of Ion Channel-Associated Diseases (MiNICAD), Valdivia, Chile.
| | - Brad S Rothberg
- Department of Medical Genetics and Molecular Biochemistry, Temple University Lewis Katz School of Medicine, Philadelphia, PA, USA.
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13
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Suzuki Y, Sawada H, Tokumasu T, Suzuki S, Ninomiya S, Shirai M, Mukai T, Saito CT, Nishimura G, Tominaga M. Novel TRPV6 mutations in the spectrum of transient neonatal hyperparathyroidism. J Physiol Sci 2020; 70:33. [PMID: 32646367 PMCID: PMC10717230 DOI: 10.1186/s12576-020-00761-2] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/11/2019] [Accepted: 07/03/2020] [Indexed: 12/23/2022]
Abstract
Maternal-fetal calcium (Ca2+) transport in the placenta plays a critical role in maintaining fetal bone mineralization. Mutations in the gene encoding the transient receptor potential cation channel, subfamily V, member 6 (TRPV6) have been identified as causative mutations of transient neonatal hyperparathyroidism due to insufficient maternal-fetal Ca2+ transport in the placenta. In this study, we found two novel mutations in subjects that have transient neonatal hyperparathyroidism. TRPV6 carrying the mutation p.Arg390His that localizes to the outer edge of the first transmembrane domain (S1) showed impaired trafficking to the plasma membrane, whereas TRPV6 having the mutation p.Gly291Ser in the sixth ankyrin repeat (AR) domain had channel properties that were comparable those of WT channels, although the increases in steady-state intracellular Ca2+ concentration could have led to Ca2+ overload and subsequent death of cells expressing this mutant channel. These results indicate that the AR6 domain contributes to TRPV6-mediated maintenance of intracellular Ca2+ concentrations, and that this region could play a novel role in regulating the activity of TRPV6 Ca2+-selective channels.
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Affiliation(s)
- Yoshiro Suzuki
- Department of Physiology, Iwate Medical University, 1-1-1 Idaidori, Yahaba-cho, Shiwa-gun, Iwate, 028-3694, Japan.
- Division of Cell Signaling, National Institute for Physiological Sciences (Exploratory Research Center on Life and Living Systems), National Institutes of Natural Sciences, Okazaki, 444-8787, Japan.
- Department of Physiological Sciences, SOKENDAI (The Graduate University for Advanced Studies), Okazaki, 444-8787, Japan.
| | - Hirotake Sawada
- Department of Fundamental Nursing, Faculty of Medicine, University of Miyazaki, Miyazaki, 889-1692, Japan
| | - Tomoko Tokumasu
- Department of Pediatrics, Kurashiki Central Hospital, Kurashiki, 710-8602, Japan
| | - Shigeru Suzuki
- Department of Pediatrics, Asahikawa-Kosei General Hospital, Asahikawa, 078-8211, Japan
- Department of Pediatrics, Asahikawa Medical University, Asahikawa, 078-8510, Japan
| | - Shinsuke Ninomiya
- Department of Clinical Genetics, Kurashiki Central Hospital, Kurashiki, 710-8602, Japan
| | - Masaru Shirai
- Department of Pediatrics, Asahikawa-Kosei General Hospital, Asahikawa, 078-8211, Japan
| | - Tokuo Mukai
- Department of Pediatrics, Asahikawa-Kosei General Hospital, Asahikawa, 078-8211, Japan
- Department of Pediatrics, Japanese Red Cross Asahikawa Hospital, Asahikawa, 070-8530, Japan
| | - Claire T Saito
- Division of Cell Signaling, National Institute for Physiological Sciences (Exploratory Research Center on Life and Living Systems), National Institutes of Natural Sciences, Okazaki, 444-8787, Japan
| | - Gen Nishimura
- Center for Intractable Disease, Saitama Medical University Hospital, Saitama, 350-0495, Japan
| | - Makoto Tominaga
- Division of Cell Signaling, National Institute for Physiological Sciences (Exploratory Research Center on Life and Living Systems), National Institutes of Natural Sciences, Okazaki, 444-8787, Japan
- Department of Physiological Sciences, SOKENDAI (The Graduate University for Advanced Studies), Okazaki, 444-8787, Japan
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14
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Evolutionary analyses reveal independent origins of gene repertoires and structural motifs associated to fast inactivation in calcium-selective TRPV channels. Sci Rep 2020; 10:8684. [PMID: 32457384 PMCID: PMC7250927 DOI: 10.1038/s41598-020-65679-6] [Citation(s) in RCA: 17] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/21/2020] [Accepted: 04/23/2020] [Indexed: 01/14/2023] Open
Abstract
Essential for calcium homeostasis, TRPV5 and TRPV6 are calcium-selective channels belonging to the transient receptor potential (TRP) gene family. In this study, we investigated the evolutionary history of these channels to add an evolutionary context to the already available physiological information. Phylogenetic analyses revealed that paralogs found in mammals, sauropsids, amphibians, and chondrichthyes, are the product of independent duplication events in the ancestor of each group. Within amniotes, we identified a traceable signature of three amino acids located at the amino-terminal intracellular region. The signature correlates with both the duplication events and the phenotype of fast inactivation observed in mammalian TRPV6 channels. Electrophysiological recordings and mutagenesis revealed that the signature sequence modulates the phenotype of fast inactivation in all clades of vertebrates but reptiles. A transcriptome analysis showed a change in tissue expression from gills, in marine vertebrates, to kidneys in terrestrial vertebrates. Our results highlight a cytoplasmatic structural triad composed by the Helix-Loop-Helix domain, the S2-S3 linker, and the TRP domain helix that is important on modulating the activity of calcium-selective TRPV channels.
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15
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Yelshanskaya MV, Nadezhdin KD, Kurnikova MG, Sobolevsky AI. Structure and function of the calcium-selective TRP channel TRPV6. J Physiol 2020; 599:2673-2697. [PMID: 32073143 DOI: 10.1113/jp279024] [Citation(s) in RCA: 22] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2019] [Accepted: 02/03/2020] [Indexed: 12/23/2022] Open
Abstract
Epithelial calcium channel TRPV6 is a member of the vanilloid subfamily of TRP channels that is permeable to cations and highly selective to Ca2+ ; it shows constitutive activity regulated negatively by Ca2+ and positively by phosphoinositol and cholesterol lipids. In this review, we describe the molecular structure of TRPV6 and discuss how its structural elements define its unique functional properties. High Ca2+ selectivity of TRPV6 originates from the narrow selectivity filter, where Ca2+ ions are directly coordinated by a ring of anionic aspartate side chains. Divalent cations Ca2+ and Ba2+ permeate TRPV6 pore according to the knock-off mechanism, while tight binding of Gd3+ to the aspartate ring blocks the channel and prevents Na+ from permeating the pore. The iris-like channel opening is accompanied by an α-to-π helical transition in the pore-lining transmembrane helix S6. As a result of this transition, the intracellular halves of the S6 helices bend and rotate by about 100 deg, exposing different residues to the channel pore in the open and closed states. Channel opening is also associated with changes in occupancy of the transmembrane domain lipid binding sites. The inhibitor 2-aminoethoxydiphenyl borate (2-APB) binds to TRPV6 in a pocket formed by the cytoplasmic half of the S1-S4 transmembrane helical bundle and shifts open-closed channel equilibrium towards the closed state by outcompeting lipids critical for activation. Ca2+ inhibits TRPV6 via binding to calmodulin (CaM), which mediates Ca2+ -dependent inactivation. The TRPV6-CaM complex exhibits 1:1 stoichiometry; one TRPV6 tetramer binds both CaM lobes, which adopt a distinct head-to-tail arrangement. The CaM C-terminal lobe plugs the channel through a unique cation-π interaction by inserting the side chain of lysine K115 into a tetra-tryptophan cage at the ion channel pore intracellular entrance. Recent studies of TRPV6 structure and function described in this review advance our understanding of the role of this channel in physiology and pathophysiology and inform new therapeutic design.
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Affiliation(s)
- Maria V Yelshanskaya
- Department of Biochemistry and Molecular Biophysics, Columbia University, 650 West 168th Street, New York, NY, 10032, USA
| | - Kirill D Nadezhdin
- Department of Biochemistry and Molecular Biophysics, Columbia University, 650 West 168th Street, New York, NY, 10032, USA
| | - Maria G Kurnikova
- Chemistry Department, Carnegie Mellon University, 4400 Fifth Ave, Pittsburgh, PA, 15213, USA
| | - Alexander I Sobolevsky
- Department of Biochemistry and Molecular Biophysics, Columbia University, 650 West 168th Street, New York, NY, 10032, USA
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16
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TRPV6 Variants Interfere with Maternal-Fetal Calcium Transport through the Placenta and Cause Transient Neonatal Hyperparathyroidism. Am J Hum Genet 2018; 102:1104-1114. [PMID: 29861107 DOI: 10.1016/j.ajhg.2018.04.006] [Citation(s) in RCA: 48] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/25/2017] [Accepted: 04/06/2018] [Indexed: 11/22/2022] Open
Abstract
Transient neonatal hyperparathyroidism (TNHP) is etiologically a heterogeneous condition. One of the etiologies is an insufficient maternal-fetal calcium transport through the placenta. We report six subjects with homozygous and/or compound-heterozygous mutations in the gene encoding the transient receptor potential cation channel, subfamily V, member 6 (TRPV6), an epithelial Ca2+-selective channel associated with this condition. Exome sequencing on two neonates with skeletal findings consistent with neonatal hyperparathyroidism identified homozygous frameshift mutations before the first transmembrane domain in a subject born to first-cousins parents of Pakistani descent as well as compound-heterozygous mutations (a combination of a frameshift mutation and an intronic mutation that alters mRNA splicing) in an individual born to a non-consanguineous couple of African descent. Subsequently, targeted mutation analysis of TRPV6 performed on four other individuals (born to non-consanguineous Japanese parents) with similar X-rays findings identified compound-heterozygous mutations. The skeletal findings improved or resolved in most subjects during the first few months of life. We identified three missense variants (at the outer edges of the second and third transmembrane domains) that alter the localization of the TRPV6: one recurrent variant at the S2-S3 loop and two recurrent variants (in the fourth ankyrin repeat domain) that impair TRPV6 stability. Compound heterozygous loss-of-function mutations for the pathogenic frameshift allele and the allele with an intronic c.607+5G>A mutation resulted in the most severe phenotype. These results suggest that TNHP is an autosomal-recessive disease caused by TRPV6 mutations that affect maternal-fetal calcium transport.
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17
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Ca 2+ Regulation of TRP Ion Channels. Int J Mol Sci 2018; 19:ijms19041256. [PMID: 29690581 PMCID: PMC5979445 DOI: 10.3390/ijms19041256] [Citation(s) in RCA: 58] [Impact Index Per Article: 9.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/29/2018] [Revised: 04/16/2018] [Accepted: 04/17/2018] [Indexed: 12/20/2022] Open
Abstract
Ca2+ signaling influences nearly every aspect of cellular life. Transient receptor potential (TRP) ion channels have emerged as cellular sensors for thermal, chemical and mechanical stimuli and are major contributors to Ca2+ signaling, playing an important role in diverse physiological and pathological processes. Notably, TRP ion channels are also one of the major downstream targets of Ca2+ signaling initiated either from TRP channels themselves or from various other sources, such as G-protein coupled receptors, giving rise to feedback regulation. TRP channels therefore function like integrators of Ca2+ signaling. A growing body of research has demonstrated different modes of Ca2+-dependent regulation of TRP ion channels and the underlying mechanisms. However, the precise actions of Ca2+ in the modulation of TRP ion channels remain elusive. Advances in Ca2+ regulation of TRP channels are critical to our understanding of the diversified functions of TRP channels and complex Ca2+ signaling.
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18
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Bate N, Caves RE, Skinner SP, Goult BT, Basran J, Mitcheson JS, Vuister GW. A Novel Mechanism for Calmodulin-Dependent Inactivation of Transient Receptor Potential Vanilloid 6. Biochemistry 2018; 57:2611-2622. [DOI: 10.1021/acs.biochem.7b01286] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Neil Bate
- Department of Molecular and Cell Biology, Leicester Institute of Structural and Chemical Biology, University of Leicester, Henry Wellcome Building, Lancaster Road, Leicester LE1 9HN, United Kingdom
| | - Rachel E. Caves
- Department of Molecular and Cell Biology, Leicester Institute of Structural and Chemical Biology, University of Leicester, Henry Wellcome Building, Lancaster Road, Leicester LE1 9HN, United Kingdom
| | - Simon P. Skinner
- Department of Molecular and Cell Biology, Leicester Institute of Structural and Chemical Biology, University of Leicester, Henry Wellcome Building, Lancaster Road, Leicester LE1 9HN, United Kingdom
| | - Benjamin T. Goult
- Department of Molecular and Cell Biology, Leicester Institute of Structural and Chemical Biology, University of Leicester, Henry Wellcome Building, Lancaster Road, Leicester LE1 9HN, United Kingdom
| | - Jaswir Basran
- Department of Molecular and Cell Biology, Leicester Institute of Structural and Chemical Biology, University of Leicester, Henry Wellcome Building, Lancaster Road, Leicester LE1 9HN, United Kingdom
| | - John S. Mitcheson
- Department of Molecular and Cell Biology, Leicester Institute of Structural and Chemical Biology, University of Leicester, Henry Wellcome Building, Lancaster Road, Leicester LE1 9HN, United Kingdom
| | - Geerten W. Vuister
- Department of Molecular and Cell Biology, Leicester Institute of Structural and Chemical Biology, University of Leicester, Henry Wellcome Building, Lancaster Road, Leicester LE1 9HN, United Kingdom
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19
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A Gate Hinge Controls the Epithelial Calcium Channel TRPV5. Sci Rep 2017; 7:45489. [PMID: 28374795 PMCID: PMC5379628 DOI: 10.1038/srep45489] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/19/2016] [Accepted: 02/27/2017] [Indexed: 12/03/2022] Open
Abstract
TRPV5 is unique within the large TRP channel family for displaying a high Ca2+ selectivity together with Ca2+-dependent inactivation. Our study aims to uncover novel insights into channel gating through in-depth structure-function analysis. We identify an exceptional tryptophan (W583) at the terminus of the intracellular pore that is unique for TRPV5 (and TRPV6). A combination of site-directed mutagenesis, biochemical and electrophysiological analysis, together with homology modeling, demonstrates that W583 is part of the gate for Ca2+ permeation. The W583 mutants show increased cell death due to profoundly enhanced Ca2+ influx, resulting from altered channel function. A glycine residue above W583 might act as flexible linker to rearrange the tryptophan gate. Furthermore, we hypothesize functional crosstalk between the pore region and carboxy terminus, involved in Ca2+-calmodulin-mediated inactivation. This study proposes a unique channel gating mechanism and delivers detailed molecular insight into the Ca2+ permeation pathway that can be extrapolated to other Ca2+-selective channels.
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20
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Velisetty P, Borbiro I, Kasimova MA, Liu L, Badheka D, Carnevale V, Rohacs T. A molecular determinant of phosphoinositide affinity in mammalian TRPV channels. Sci Rep 2016; 6:27652. [PMID: 27291418 PMCID: PMC4904367 DOI: 10.1038/srep27652] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/16/2015] [Accepted: 05/12/2016] [Indexed: 11/09/2022] Open
Abstract
Phosphatidylinositol 4,5-bisphosphate [PI(4,5)P2] is an important cofactor for ion channels. Affinity for this lipid is a major determinant of channel inhibition by depletion of PI(4,5)P2 upon phospholipase C (PLC) activation. Little is known about what determines PI(4,5)P2 affinity in mammalian ion channels. Here we report that two members of the Transient Receptor Potential Vanilloid (TRPV) ion channel family, TRPV5 and TRPV6 lack a positively charged residue in the TM4-TM5 loop that was shown to interact with PI(4,5)P2 in TRPV1, which shows high affinity for this lipid. When this positively charged residue was introduced to either TRPV6 or TRPV5, they displayed markedly higher affinities for PI(4,5)P2, and were largely resistant to inhibition by PI(4,5)P2 depletion. Furthermore, Ca(2+)-induced inactivation of TRPV6 was essentially eliminated in the G488R mutant, showing the importance of PLC-mediated PI(4,5)P2 depletion in this process. Computational modeling shows that the introduced positive charge interacts with PI(4,5)P2 in TRPV6.
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Affiliation(s)
- Phanindra Velisetty
- Department of Pharmacology, Physiology and Neuroscience, Rutgers - New Jersey Medical School, Newark, NJ 07103, USA
| | - Istvan Borbiro
- Department of Pharmacology, Physiology and Neuroscience, Rutgers - New Jersey Medical School, Newark, NJ 07103, USA
| | - Marina A Kasimova
- Institute for Computational Molecular Science at Temple University in Philadelphia, PA, 19122, USA
| | - Luyu Liu
- Department of Pharmacology, Physiology and Neuroscience, Rutgers - New Jersey Medical School, Newark, NJ 07103, USA
| | - Doreen Badheka
- Department of Pharmacology, Physiology and Neuroscience, Rutgers - New Jersey Medical School, Newark, NJ 07103, USA
| | - Vincenzo Carnevale
- Institute for Computational Molecular Science at Temple University in Philadelphia, PA, 19122, USA
| | - Tibor Rohacs
- Department of Pharmacology, Physiology and Neuroscience, Rutgers - New Jersey Medical School, Newark, NJ 07103, USA
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21
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van Loon EPM, Little R, Prehar S, Bindels RJM, Cartwright EJ, Hoenderop JGJ. Calcium Extrusion Pump PMCA4: A New Player in Renal Calcium Handling? PLoS One 2016; 11:e0153483. [PMID: 27101128 PMCID: PMC4839660 DOI: 10.1371/journal.pone.0153483] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/10/2015] [Accepted: 03/17/2016] [Indexed: 11/19/2022] Open
Abstract
Calcium (Ca2+) is vital for multiple processes in the body, and maintenance of the electrolyte concentration is required for everyday physiological function. In the kidney, and more specifically, in the late distal convoluted tubule and connecting tubule, the fine-tuning of Ca2+ reabsorption from the pro-urine takes place. Here, Ca2+ enters the epithelial cell via the transient receptor potential vanilloid receptor type 5 (TRPV5) channel, diffuses to the basolateral side bound to calbindin-D28k and is extruded to the blood compartment via the Na+/Ca2+ exchanger 1 (NCX1) and the plasma membrane Ca2+ ATPase (PMCA). Traditionally, PMCA1 was considered to be the primary Ca2+ pump in this process. However, in recent studies TRPV5-expressing tubules were shown to highly express PMCA4. Therefore, PMCA4 may have a predominant role in renal Ca2+ handling. This study aimed to elucidate the role of PMCA4 in Ca2+ homeostasis by characterizing the Ca2+ balance, and renal and duodenal Ca2+-related gene expression in PMCA4 knockout mice. The daily water intake of PMCA4 knockout mice was significantly lower compared to wild type littermates. There was no significant difference in serum Ca2+ level or urinary Ca2+ excretion between groups. In addition, renal and duodenal mRNA expression levels of Ca2+-related genes, including TRPV5, TRPV6, calbindin-D28k, calbindin-D9k, NCX1 and PMCA1 were similar in wild type and knockout mice. Serum FGF23 levels were significantly increased in PMCA4 knockout mice. In conclusion, PMCA4 has no discernible role in normal renal Ca2+ handling as no urinary Ca2+ wasting was observed. Further investigation of the exact role of PMCA4 in the distal convoluted tubule and connecting tubule is required.
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Affiliation(s)
- Ellen P. M. van Loon
- Department of Physiology, Radboud Institute for Molecular Life Sciences, Radboud university medical center, Nijmegen, The Netherlands
| | - Robert Little
- Institute of Cardiovascular Sciences, Manchester Academic Health Sciences Centre, University of Manchester, Manchester, United Kingdom
| | - Sukhpal Prehar
- Institute of Cardiovascular Sciences, Manchester Academic Health Sciences Centre, University of Manchester, Manchester, United Kingdom
| | - René J. M. Bindels
- Department of Physiology, Radboud Institute for Molecular Life Sciences, Radboud university medical center, Nijmegen, The Netherlands
| | - Elizabeth J. Cartwright
- Institute of Cardiovascular Sciences, Manchester Academic Health Sciences Centre, University of Manchester, Manchester, United Kingdom
| | - Joost G. J. Hoenderop
- Department of Physiology, Radboud Institute for Molecular Life Sciences, Radboud university medical center, Nijmegen, The Netherlands
- * E-mail:
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22
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Lameris AL, Nevalainen PI, Reijnen D, Simons E, Eygensteyn J, Monnens L, Bindels RJM, Hoenderop JGJ. Segmental transport of Ca²⁺ and Mg²⁺ along the gastrointestinal tract. Am J Physiol Gastrointest Liver Physiol 2015; 308:G206-16. [PMID: 25477372 DOI: 10.1152/ajpgi.00093.2014] [Citation(s) in RCA: 40] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/08/2023]
Abstract
Calcium (Ca(2+)) and magnesium (Mg(2+)) ions are involved in many vital physiological functions. Since dietary intake is the only source of minerals for the body, intestinal absorption is essential for normal homeostatic levels. The aim of this study was to characterize the absorption of Ca(2+) as well as Mg(2+) along the gastrointestinal tract at a molecular and functional level. In both humans and mice the Ca(2+) channel transient receptor potential vanilloid subtype 6 (TRPV6) is expressed in the proximal intestinal segments, whereas Mg(2+) channel transient receptor potential melastatin subtype 6 (TRPM6) is expressed in the distal parts of the intestine. A method was established to measure the rate of Mg(2+) absorption from the intestine in a time-dependent manner by use of (25)Mg(2+). In addition, local absorption of Ca(2+) and Mg(2+) in different segments of the intestine of mice was determined by using surgically implanted intestinal cannulas. By these methods, it was demonstrated that intestinal absorption of Mg(2+) is regulated by dietary needs in a vitamin D-independent manner. Also, it was shown that at low luminal concentrations, favoring transcellular absorption, Ca(2+) transport mainly takes place in the proximal segments of the intestine, whereas Mg(2+) absorption predominantly occurs in the distal part of the gastrointestinal tract. Vitamin D treatment of mice increased serum Mg(2+) levels and 24-h urinary Mg(2+) excretion, but not intestinal absorption of (25)Mg(2+). Segmental cannulation of the intestine and time-dependent absorption studies using (25)Mg(2+) provide new ways to study intestinal Mg(2+) absorption.
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Affiliation(s)
- Anke L Lameris
- Department of Physiology, Radboud University Medical Center, Nijmegen, The Netherlands
| | - Pasi I Nevalainen
- School of Medicine, University of Tampere, Tampere, Finland; Department of Internal Medicine, Tampere University Hospital, Tampere, Finland
| | - Daphne Reijnen
- Central Animal Facility, Radboud University, Nijmegen, The Netherlands; and
| | - Ellen Simons
- Department of Physiology, Radboud University Medical Center, Nijmegen, The Netherlands
| | - Jelle Eygensteyn
- Department of General Instrumentation, Faculty of Sciences, Radboud University, Nijmegen, The Netherlands
| | - Leo Monnens
- Department of Physiology, Radboud University Medical Center, Nijmegen, The Netherlands
| | - René J M Bindels
- Department of Physiology, Radboud University Medical Center, Nijmegen, The Netherlands
| | - Joost G J Hoenderop
- Department of Physiology, Radboud University Medical Center, Nijmegen, The Netherlands;
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23
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TRPV6 calcium channel translocates to the plasma membrane via Orai1-mediated mechanism and controls cancer cell survival. Proc Natl Acad Sci U S A 2014; 111:E3870-9. [PMID: 25172921 DOI: 10.1073/pnas.1413409111] [Citation(s) in RCA: 76] [Impact Index Per Article: 7.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023] Open
Abstract
Transient receptor potential vanilloid subfamily member 6 (TRPV6) is a highly selective calcium channel that has been considered as a part of store-operated calcium entry (SOCE). Despite its first discovery in the early 2000s, the role of this channel in prostate cancer (PCa) remained, until now, obscure. Here we show that TRPV6 mediates calcium entry, which is highly increased in PCa due to the remodeling mechanism involving the translocation of the TRPV6 channel to the plasma membrane via the Orai1/TRPC1-mediated Ca(2+)/Annexin I/S100A11 pathway, partially contributing to SOCE. The TRPV6 calcium channel is expressed de novo by the PCa cell to increase its survival by enhancing proliferation and conferring apoptosis resistance. Xenografts in nude mice and bone metastasis models confirmed the remarkable aggressiveness of TRPV6-overexpressing tumors. Immunohistochemical analysis of these demonstrated the increased expression of clinical markers such as Ki-67, prostate specific antigen, synaptophysin, CD31, and CD56, which are strongly associated with a poor prognosis. Thus, the TRPV6 channel acquires its oncogenic potential in PCa due to the remodeling mechanism via the Orai1-mediated Ca(2+)/Annexin I/S100A11 pathway.
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24
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Nilius B, Szallasi A. Transient Receptor Potential Channels as Drug Targets: From the Science of Basic Research to the Art of Medicine. Pharmacol Rev 2014; 66:676-814. [DOI: 10.1124/pr.113.008268] [Citation(s) in RCA: 348] [Impact Index Per Article: 34.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022] Open
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25
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Abstract
TRPV5 is one of the two channels in the TRPV family that exhibit high selectivity to Ca(2+) ions. TRPV5 mediates Ca(2+) influx into cells as the first step to transport Ca(2+) across epithelia. The specialized distribution in the distal tubule of the kidney positions TRPV5 as a key player in Ca(2+) reabsorption. The responsiveness in expression and/or activity of TRPV5 to hormones such as 1,25-dihydroxyvitamin D3, parathyroid hormone, estrogen, and testosterone makes TRPV5 suitable for its role in the fine-tuning of Ca(2+) reabsorption. This role is further optimized by the modulation of TRPV5 trafficking and activity via its binding partners; co-expressed proteins; tubular factors such as calbindin-D28k, calmodulin, klotho, uromodulin, and plasmin; extracellular and intracellular factors such as proton, Mg(2+), Ca(2+), and phosphatidylinositol-4,5-bisphosphate; and fluid flow. These regulations allow TRPV5 to adjust its overall activity in response to the body's demand for Ca(2+) and to prevent kidney stone formation. A point mutation in mouse Trpv5 gene leads to hypercalciuria similar to Trpv5 knockout mice, suggesting a possible role of TRPV5 in hypercalciuric disorders in humans. In addition, the single nucleotide polymorphisms in Trpv5 gene prevalently present in African descents may contribute to the efficient renal Ca(2+) reabsorption among African descendants. TRPV5 represents a potential therapeutic target for disorders with altered Ca(2+) homeostasis.
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Affiliation(s)
- Tao Na
- Cell Collection and Research Center, Institute for Biological Product Control, National Institutes for Food and Drug Control, Beijing, China
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26
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Abstract
TRPV6 (former synonyms ECAC2, CaT1, CaT-like) displays several specific features which makes it unique among the members of the mammalian Trp gene family (1) TRPV6 (and its closest relative, TRPV5) are the only highly Ca(2+)-selective channels of the entire TRP superfamily (Peng et al. 1999; Wissenbach et al. 2001; Voets et al. 2004). (2) Translation of Trpv6 initiates at a non-AUG codon, at ACG, located upstream of the annotated AUG, which is not used for initiation (Fecher-Trost et al. 2013). The ACG codon is nevertheless decoded by methionine. Not only a very rare event in eukaryotic biology, the full-length TRPV6 protein existing in vivo comprises an amino terminus extended by 40 amino acid residues compared to the annotated truncated TRPV6 protein which has been used in most studies on TRPV6 channel activity so far. (In the following numbering occurs according to this full-length protein, with the numbers of the so far annotated truncated protein in brackets). (3) Only in humans a coupled polymorphism of Trpv6 exists causing three amino acid exchanges and resulting in an ancestral Trpv6 haplotype and a so-called derived Trpv6 haplotype (Wissenbach et al. 2001). The ancestral allele encodes the amino acid residues C197(157), M418(378) and M721(681) and the derived alleles R197(157), V418(378) and T721(681). The ancestral haplotype is found in all species, the derived Trpv6 haplotype has only been identified in humans, and its frequency increases with the distance to the African continent. Apparently the Trpv6 gene has been a strong target for selection in humans, and its derived variant is one of the few examples showing consistently differences to the orthologues genes of other primates (Akey et al. 2004, 2006; Stajich and Hahn 2005; Hughes et al. 2008). (4) The Trpv6 gene expression is significantly upregulated in several human malignancies including the most common cancers, prostate and breast cancer (Wissenbach et al. 2001; Zhuang et al. 2002; Fixemer et al. 2003; Bolanz et al. 2008). (5) Male mice lacking functional TRPV6 channels are hypo-/infertile making TRPV6 one of the very few channels essential for male fertility (Weissgerber et al. 2011, 2012).
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Affiliation(s)
- Claudia Fecher-Trost
- Institut für Experimentelle und Klinische Pharmakologie und Toxikologie, Universität des Saarlandes, 66421, Homburg, Germany
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Dong XL, Zhang Y, Wong MS. Estrogen deficiency-induced Ca balance impairment is associated with decrease in expression of epithelial Ca transport proteins in aged female rats. Life Sci 2013; 96:26-32. [PMID: 24378673 DOI: 10.1016/j.lfs.2013.12.025] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/05/2013] [Revised: 12/12/2013] [Accepted: 12/14/2013] [Indexed: 01/12/2023]
Abstract
AIMS The study is designed to determine whether estrogen and vitamin D endocrine systems interact to regulate calcium (Ca) balance as well as changes in mRNA expression of epithelial Ca transport proteins involved in intestinal and renal Ca transport in aging animals in response to ovariectomy and low dietary Ca intake. MAIN METHODS Eleven-month-old female sham or ovariectomized (OVX) rats were divided into four groups and fed with either a low-Ca (LCD; 0.1% Ca, 0.65% P) or a high-Ca (HCD; 1.2% Ca, 0.65% P) diet for 12weeks. Ca balance and mRNA expression of Ca transport proteins in the intestine and kidney from rats were systematically studied. KEY FINDINGS OVX rats fed with LCD resulted in a negative Ca balance. LCD suppressed serum Ca in OVX but not sham rats, resulting in an induction of serum PTH and 1,25(OH)2D3 levels. The surge in serum 1,25(OH)2D3 levels in LCD-fed OVX rats was associated with an increase in mRNA expression of intestinal transient receptor potential cation channel (TRPV6) and calbindin D9k (CaBP9k) as well as renal vitamin D receptor (VDR), but such an induction was unable to restore Ca balance in vivo. In contrast, the negative Ca balance was associated with suppression of intestinal plasma membrane Ca pump (PMCA1b) and renal transient receptor potential cation channel (TRPV5), calbindin D28k (CaBP28k) and PMCA1b mRNA expression in aged OVX rats. SIGNIFICANCE Negative Ca balance in aged female OVX rats is associated with estrogen-dependent and vitamin D-independent downregulation of epithelial Ca transport protein mRNA expression.
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Affiliation(s)
- Xiao-Li Dong
- Department of Applied Biology and Chemical Technology, The Hong Kong Polytechnic University, Hung Hom, Kowloon, Hong Kong, People's Republic of China
| | - Yan Zhang
- Department of Applied Biology and Chemical Technology, The Hong Kong Polytechnic University, Hung Hom, Kowloon, Hong Kong, People's Republic of China; Center for Systems Biomedical Sciences, University of Shanghai for Science and Technology, Shanghai 200093, People's Republic of China
| | - Man-Sau Wong
- Department of Applied Biology and Chemical Technology, The Hong Kong Polytechnic University, Hung Hom, Kowloon, Hong Kong, People's Republic of China; State Key Laboratory of Chinese Medicine and Molecular Pharmacology (Incubation), Shenzhen 518057, People's Republic of China.
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28
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Abstract
TRP channels constitute a large superfamily of cation channel forming proteins, all related to the gene product of the transient receptor potential (trp) locus in Drosophila. In mammals, 28 different TRP channel genes have been identified, which exhibit a large variety of functional properties and play diverse cellular and physiological roles. In this article, we provide a brief and systematic summary of expression, function, and (patho)physiological role of the mammalian TRP channels.
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Affiliation(s)
- Maarten Gees
- Laboratory Ion Channel Research and TRP Research Platform Leuven (TRPLe), KU Leuven, Campus Gasthuisberg, Leuven, Belgium
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29
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Cao C, Zakharian E, Borbiro I, Rohacs T. Interplay between calmodulin and phosphatidylinositol 4,5-bisphosphate in Ca2+-induced inactivation of transient receptor potential vanilloid 6 channels. J Biol Chem 2013; 288:5278-90. [PMID: 23300090 DOI: 10.1074/jbc.m112.409482] [Citation(s) in RCA: 42] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
The epithelial Ca(2+) channel transient receptor potential vanilloid 6 (TRPV6) undergoes Ca(2+)-induced inactivation that protects the cell from toxic Ca(2+) overload and may also limit intestinal Ca(2+) transport. To dissect the roles of individual signaling pathways in this phenomenon, we studied the effects of Ca(2+), calmodulin (CaM), and phosphatidylinositol 4,5-bisphosphate (PI(4,5)P(2)) in excised inside-out patches. The activity of TRPV6 strictly depended on the presence of PI(4,5)P(2), and Ca(2+)-CaM inhibited the channel at physiologically relevant concentrations. Ca(2+) alone also inhibited TRPV6 at high concentrations (IC(50) = ∼20 μM). A double mutation in the distal C-terminal CaM-binding site of TRPV6 (W695A/R699E) essentially eliminated inhibition by CaM in excised patches. In whole cell patch clamp experiments, this mutation reduced but did not eliminate Ca(2+)-induced inactivation. Providing excess PI(4,5)P(2) reduced the inhibition by CaM in excised patches and in planar lipid bilayers, but PI(4,5)P(2) did not inhibit binding of CaM to the C terminus of the channel. Overall, our data show a complex interplay between CaM and PI(4,5)P(2) and show that Ca(2+), CaM, and the depletion of PI(4,5)P(2) all contribute to inactivation of TRPV6.
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Affiliation(s)
- Chike Cao
- Department of Pharmacology and Physiology, University of Medicine and Dentistry of New Jersey, New Jersey Medical School, Newark, New Jersey 07103, USA
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Yatabe MS, Yatabe J, Takano K, Murakami Y, Sakuta R, Abe S, Sanada H, Kimura J, Watanabe T. Effects of a high-sodium diet on renal tubule Ca2+ transporter and claudin expression in Wistar-Kyoto rats. BMC Nephrol 2012. [PMID: 23199000 PMCID: PMC3538060 DOI: 10.1186/1471-2369-13-160] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022] Open
Abstract
Background Urinary Ca2+ excretion increases with dietary NaCl. NaCl-induced calciuria may be associated with hypertension, urinary stone formation and osteoporosis, but its mechanism and long-term effects are not fully understood. This study examined alterations in the expressions of renal Ca2+ transporters, channels and claudins upon salt loading to better understand the mechanism of salt-induced urinary Ca2+ loss. Methods Eight-week old Wistar-Kyoto rats were fed either 0.3% or 8% NaCl diet for 8 weeks. Renal cortical expressions of Na+/Ca2+ exchanger 1 (NCX1), Ca2+ pump (PCMA1b), Ca2+ channel (TRPV5), calbindin-D28k, and claudins (CLDN-2, -7, -8, -16 and −19) were analyzed by quantitative PCR, western blot and/or immunohistochemistry. Results Fractional excretion of Ca2+ increased 6.0 fold with high-salt diet. Renal cortical claudin-2 protein decreased by approximately 20% with decreased immunological staining on tissue sections. Claudin-16 and −19 expressions were not altered. Renal cortical TRPV5, calbindin-D28k and NCX1 expressions increased 1.6, 1.5 and 1.2 fold, respectively. Conclusions Chronic high-salt diet decreased claudin-2 protein and increased renal TRPV5, calbindin-D28k, and NCX1. Salt loading is known to reduce the proximal tubular reabsorption of both Na+ and Ca2+. The reduction in claudin-2 protein expression may be partly responsible for the reduced Ca2+ reabsorption in this segment. The concerted upregulation of more distal Ca2+-transporting molecules may be a physiological response to curtail the loss of Ca2+, although the magnitude of compensation does not seem adequate to bring the urinary Ca2+ excretion down to that of the normal-diet group.
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Affiliation(s)
- Midori Sasaki Yatabe
- Department of Pharmacology, Fukushima Medical University School of Medicine, 1 Hikarigaoka, Fukushima, 960-1295, Japan.
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Kovalevskaya NV, Bokhovchuk FM, Vuister GW. The TRPV5/6 calcium channels contain multiple calmodulin binding sites with differential binding properties. ACTA ACUST UNITED AC 2012; 13:91-100. [PMID: 22354706 PMCID: PMC3375010 DOI: 10.1007/s10969-012-9128-4] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2011] [Accepted: 02/02/2012] [Indexed: 11/26/2022]
Abstract
The epithelial Ca2+ channels TRPV5/6 (transient receptor potential vanilloid 5/6) are thoroughly regulated in order to fine-tune the amount of Ca2+ reabsorption. Calmodulin has been shown to be involved into calcium-dependent inactivation of TRPV5/6 channels by binding directly to the distal C-terminal fragment of the channels (de Groot et al. in Mol Cell Biol 31:2845–2853, 12). Here, we investigate this binding in detail and find significant differences between TRPV5 and TRPV6. We also identify and characterize in vitro four other CaM binding fragments of TRPV5/6, which likely are also involved in TRPV5/6 channel regulation. The five CaM binding sites display diversity in binding modes, binding stoichiometries and binding affinities, which may fine-tune the response of the channels to varying Ca2+-concentrations.
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Affiliation(s)
- Nadezda V Kovalevskaya
- Department of Protein Biophysics, IMM, Radboud University Nijmegen, Heyendaalseweg 135, 6525 AJ, Nijmegen, The Netherlands.
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Abstract
Most dairy cows exhibit different degrees of hypocalcaemia around calving because the gestational Ca requirements shift to the disproportionately high Ca requirements of lactation. Ca homeostasis is a robust system that effectively adapts to changes in Ca demand or supply. However, these adaptations often are not rapid enough to avoid hypocalcaemia. A delay in the reconfiguration of intestinal Ca absorption and bone resorption is probably the underlying cause of this transient hypocalcaemia. Several dietary factors that affect different aspects of Ca metabolism are known to reduce the incidence of milk fever. The present review describes the interactions between nutrition and Ca homeostasis using observations from cattle and extrapolations from other species and aims to quantitatively model the effects of the nutritional approaches that are used to induce dry cows into an early adaptation of Ca metabolism. The present model suggests that reducing dietary cation–anion difference (DCAD) increases Ca clearance from the blood by dietary induction of systemic acidosis, which results in hypercalciuria due to the loss of function of the renal Ca transient receptor potential vanilloid channel TRPV5. Alternatively, reducing the gastrointestinal availability of Ca by reducing dietary Ca or its nutritional availability will also induce the activation of Ca metabolism to compensate for basal blood Ca clearance. Our model of gastrointestinal Ca availability as well as blood Ca clearance in the transition dairy cow allowed us to conclude that the most common dietary strategies for milk fever prevention may have analogous modes of action that are based on the principle of metabolic adaptation before calving.
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Peng JB. TRPV5 and TRPV6 in transcellular Ca(2+) transport: regulation, gene duplication, and polymorphisms in African populations. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2011; 704:239-75. [PMID: 21290300 DOI: 10.1007/978-94-007-0265-3_14] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
TRPV5 and TRPV6 are unique members of the TRP super family. They are highly selective for Ca(2+) ions with multiple layers of Ca(2+)-dependent inactivation mechanisms, expressed at the apical membrane of Ca(2+) transporting epithelia, and robustly responsive to 1,25-dihydroxivitamin D(3). These features are well suited for their roles as Ca(2+) entry channels in the first step of transcellular Ca(2+) transport pathways, which are involved in intestinal absorption, renal reabsorption of Ca(2+), placental transfer of Ca(2+) to fetus, and many other processes. While TRPV6 is more broadly expressed in a variety of tissues such as esophagus, stomach, small intestine, colon, kidney, placenta, pancreas, prostate, uterus, salivary gland, and sweat gland, TRPV5 expression is relatively restricted to the distal convoluted tubule and connecting tubule of the kidney. There is only one TRPV6-like gene in fish and birds in comparison to both TRPV5 and TRPV6 genes in mammals, indicating TRPV5 gene was likely generated from duplication of TRPV6 gene during the evolution of mammals to meet the needs of complex renal function. TRPV5 and TRPV6 are subjected to vigorous regulations under physiological, pathological, and therapeutic conditions. The elevated TRPV6 level in malignant tumors such as prostate and breast cancers makes it a potential therapeutic target. TRPV6, and to a lesser extent TRPV5, exhibit unusually high levels of single nucleotide polymorphisms (SNPs) in African populations as compared to other populations, indicating TRPV6 gene was under selective pressure during or after humans migrated out of Africa. The SNPs of TRPV6 and TRPV5 likely contribute to the Ca(2+) conservation mechanisms in African populations.
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Affiliation(s)
- Ji-Bin Peng
- Division of Nephrology, Department of Medicine, Nephrology Research and Training Center, University of Alabama at Birmingham, Birmingham, AL 35294, USA.
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Functional and structural studies of TRP channels heterologously expressed in budding yeast. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2011; 704:25-40. [PMID: 21290288 DOI: 10.1007/978-94-007-0265-3_2] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Abstract
The transient receptor potential (TRP) superfamily is one of the largest families of cation channels. The metazoan TRP family has been subdivided into major branches: TRPC, TRPA, TRPM, TRPP, TRPV, TRPML, and TRPN, while the TRPY family is found in fungi. They are involved in many physiological processes and in the pathogenesis of various disorders. An efficient high-yield expression system for TRP channels is a necessary step towards biophysical and biochemical characterization and structural analysis of these proteins, and the budding yeast, Saccharomyces cerevisiae has proven to be very useful for this purpose. In addition, genetic screens in this organism can be carried out rapidly to identify amino acid residues important for function and to generate useful mutants. Here we present an overview of current developments towards understanding TRP channel function and structure using Saccharomyces cerevisiae as an expression system. In addition, we will summarize recent progress in understanding gating mechanisms of TRP channels using endogenously expressing TRPY channels in S. cerevisiae, and insights gained from genetic screens for mutants in mammalian channels. The discussion will focus particular attention of the use of cryo-electron microscopy (cryo-EM) to determine TRP channel structure, and outlines a "divide and concur" methodology for combining high resolution structures of TRP channel domains determined by X-ray crystallography with lower resolution techniques including cryo-EM and spectroscopy.
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Wu LJ, Sweet TB, Clapham DE. International Union of Basic and Clinical Pharmacology. LXXVI. Current progress in the mammalian TRP ion channel family. Pharmacol Rev 2010; 62:381-404. [PMID: 20716668 DOI: 10.1124/pr.110.002725] [Citation(s) in RCA: 426] [Impact Index Per Article: 30.4] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022] Open
Abstract
Transient receptor potential (TRP) channels are a large family of ion channel proteins, surpassed in number in mammals only by voltage-gated potassium channels. TRP channels are activated and regulated through strikingly diverse mechanisms, making them suitable candidates for cellular sensors. They respond to environmental stimuli such as temperature, pH, osmolarity, pheromones, taste, and plant compounds, and intracellular stimuli such as Ca(2+) and phosphatidylinositol signal transduction pathways. However, it is still largely unknown how TRP channels are activated in vivo. Despite the uncertainties, emerging evidence using TRP channel knockout mice indicates that these channels have broad function in physiology. Here we review the recent progress on the physiology, pharmacology and pathophysiological function of mammalian TRP channels.
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Affiliation(s)
- Long-Jun Wu
- Howard Hughes Medical Institute, Department of Cardiology, Children's Hospital Boston, 320 Longwood Avenue, Boston, MA 02115, USA
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Lee KP, Nair AV, Grimm C, van Zeeland F, Heller S, Bindels RJM, Hoenderop JGJ. A helix-breaking mutation in the epithelial Ca(2+) channel TRPV5 leads to reduced Ca(2+)-dependent inactivation. Cell Calcium 2010; 48:275-87. [PMID: 21035851 DOI: 10.1016/j.ceca.2010.09.007] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/02/2010] [Revised: 09/14/2010] [Accepted: 09/15/2010] [Indexed: 12/01/2022]
Abstract
TRPV5, a member of transient receptor potential (TRP) superfamily of ion channels, plays a crucial role in epithelial calcium transport in the kidney. This channel has a high selectivity for Ca(2+) and is tightly regulated by intracellular Ca(2+) concentrations. Recently it was shown that the molecular basis of deafness in varitint-waddler mouse is the result of hair cell death caused by the constitutive activity of transient receptor potential mucolipin 3 (TRPML3) channel carrying a helix breaking mutation, A419P, at the intracellular proximity of the fifth transmembrane domain (TM5). This mutation significantly elevates intracellular Ca(2+) concentration and causes rapid cell death. Here we show that substituting the equivalent location in TRPV5, the M490, to proline significantly modulates Ca(2+)-dependent inactivation of TRPV5. The single channel conductance, time constant of inactivation (τ) and half maximal inhibition constant (IC(50)) of TRPV5(M490P) were increased compared to TRPV5(WT). Moreover TRPV5(M490P) showed lower Ca(2+) permeability. Out of different point mutations created to characterize the importance of M490 in Ca(2+)-dependent inactivation, only TRPV5(M490P)-expressing cells showed apoptosis and extremely altered Ca(2+)-dependent inactivation. In conclusion, the TRPV5 channel is susceptible for helix breaking mutations and the proximal intracellular region of TM5 of this channel plays an important role in Ca(2+)-dependent inactivation.
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Affiliation(s)
- Kyu Pil Lee
- Department of Physiology, Radboud University Nijmegen Medical Centre, The Netherlands
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Gees M, Colsoul B, Nilius B. The role of transient receptor potential cation channels in Ca2+ signaling. Cold Spring Harb Perspect Biol 2010; 2:a003962. [PMID: 20861159 DOI: 10.1101/cshperspect.a003962] [Citation(s) in RCA: 310] [Impact Index Per Article: 22.1] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
Abstract
The 28 mammalian members of the super-family of transient receptor potential (TRP) channels are cation channels, mostly permeable to both monovalent and divalent cations, and can be subdivided into six main subfamilies: the TRPC (canonical), TRPV (vanilloid), TRPM (melastatin), TRPP (polycystin), TRPML (mucolipin), and the TRPA (ankyrin) groups. TRP channels are widely expressed in a large number of different tissues and cell types, and their biological roles appear to be equally diverse. In general, considered as polymodal cell sensors, they play a much more diverse role than anticipated. Functionally, TRP channels, when activated, cause cell depolarization, which may trigger a plethora of voltage-dependent ion channels. Upon stimulation, Ca2+ permeable TRP channels generate changes in the intracellular Ca2+ concentration, [Ca2+]i, by Ca2+ entry via the plasma membrane. However, more and more evidence is arising that TRP channels are also located in intracellular organelles and serve as intracellular Ca2+ release channels. This review focuses on three major tasks of TRP channels: (1) the function of TRP channels as Ca2+ entry channels; (2) the electrogenic actions of TRPs; and (3) TRPs as Ca2+ release channels in intracellular organelles.
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Affiliation(s)
- Maarten Gees
- KU Leuven, Department of Molecular Cell Biology, Laboratory Ion Channel Research, Campus Gasthuisberg, Herestraat 49, bus 802, Leuven, Belgium
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Functional Analysis of TRPV6 Polymorphisms. Lab Anim Res 2010. [DOI: 10.5625/lar.2010.26.4.331] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
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Al-Ansary D, Bogeski I, Disteldorf BMJ, Becherer U, Niemeyer BA. ATP modulates Ca2+ uptake by TRPV6 and is counteracted by isoform-specific phosphorylation. FASEB J 2009; 24:425-35. [PMID: 19805577 DOI: 10.1096/fj.09-141481] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Abstract
Ca(2+) homeostasis requires balanced uptake and extrusion, and dysregulation leads to disease. TRPV6 channels are homeostasis regulators, are upregulated in certain cancers, and show an unusual allele-specific evolution in humans. To understand how Ca(2+) uptake can be adapted to changes in metabolic status, we investigate regulation of Ca(2+)-influx by ATP and phosphorylation. We show that ATP binds to TRPV6, reduces whole-cell current increments, and prevents channel rundown with an EC(50) of 380 microM. By using both biochemical binding studies and patch-clamp analyses of wild-type and mutant channels, we have mapped one relevant site for regulation by ATP to residues within the ankyrin repeat domain (ARD) and identify an additional C-terminal binding region. Stimulation of PKC largely prevented the effects of ATP. This regulation requires PKC(betaII) and defined phosphorylation sites within the ARD and the C-terminus. Both regulatory sites act synergistically to constitute a novel mechanism by which ATP stabilizes channel activity and acts as a metabolic switch for Ca(2+) influx. Decreases in ATP concentration or activation of PKC(betaII) disable regulation of the channels by ATP, rendering them more susceptible to inactivation and rundown and preventing Ca(2+) overload.
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Affiliation(s)
- Dalia Al-Ansary
- Department of Pharmacology and Toxicology, University of Saarland, 66421 Homburg, Germany
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40
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Choi Y, Seo H, Kim M, Ka H. Dynamic expression of calcium-regulatory molecules, TRPV6 and S100G, in the uterine endometrium during pregnancy in pigs. Biol Reprod 2009; 81:1122-30. [PMID: 19641180 DOI: 10.1095/biolreprod.109.076703] [Citation(s) in RCA: 40] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/01/2022] Open
Abstract
Calcium ions have been implicated in the establishment and maintenance of pregnancy, but the regulatory mechanisms of calcium ions in the uterine endometrium and conceptus are not well understood in pigs. Recently, we showed that TRPV6, a calcium ion channel protein associated with cellular entry of calcium ions, is highly expressed in the uterine endometrium during the implantation period in pigs. In the present study, we investigated spatial and temporal expression and regulation of TRPV6 and S100G, an intracellular calcium-regulatory molecule, in the uterine endometrium during the estrous cycle and pregnancy in pigs. TRPV6 expression was maintained at significantly higher levels in the uterine endometrium during pregnancy compared with levels during the estrous cycle. TRPV6 transcripts and proteins were localized mainly to luminal epithelial cells (LE) and weakly to glandular epithelial cells (GE) and chorionic membrane (CM) during pregnancy. TRPV6 expression was also detected in conceptuses on Day (D) 12 and D15. TRPV6 mRNA levels in the endometrium were increased by estrogen treatment. S100G expression showed a biphasic pattern of increases on D12 of pregnancy and from D60 to term pregnancy, and it localized primarily to LE during early pregnancy and to LE, GE, and CM from D30 to term pregnancy. These results indicate that spatial and temporal expression of TRPV6 and S100G is dynamically regulated in the uterine endometrium during pregnancy and that endometrial regulation of calcium ion concentration by TRPV6 and S100G may be critical for the establishment and maintenance of pregnancy in pigs.
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Affiliation(s)
- Yohan Choi
- Division of Biological Science and Technology and Institute of Biomaterials, Yonsei University, Wonju, Republic of Korea
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41
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de Groot T, Lee K, Langeslag M, Xi Q, Jalink K, Bindels RJM, Hoenderop JGJ. Parathyroid hormone activates TRPV5 via PKA-dependent phosphorylation. J Am Soc Nephrol 2009; 20:1693-704. [PMID: 19423690 DOI: 10.1681/asn.2008080873] [Citation(s) in RCA: 124] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022] Open
Abstract
Low extracellular calcium (Ca(2+)) promotes release of parathyroid hormone (PTH), which acts on multiple organs to maintain overall Ca(2+) balance. In the distal part of the nephron, PTH stimulates active Ca(2+) reabsorption via the adenylyl cyclase-cAMP-protein kinase A (PKA) pathway, but the molecular target of this pathway is unknown. The transient receptor potential vanilloid 5 (TRPV5) channel constitutes the luminal gate for Ca(2+) entry in the distal convoluted tubule and has several putative PKA phosphorylation sites. Here, we investigated the effect of PTH-induced cAMP signaling on TRPV5 activity. Using fluorescence resonance energy transfer, we studied cAMP and Ca(2+) dynamics during PTH stimulation of HEK293 cells that coexpressed the PTH receptor and TRPV5. PTH increased cAMP levels, followed by a rise in TRPV5-mediated Ca(2+) influx. PTH (1 to 31) and forskolin, which activate the cAMP pathway, mimicked the stimulation of TRPV5 activity. Remarkably, TRPV5 activation was limited to conditions of strong intracellular Ca(2+) buffering. Cell surface biotinylation studies demonstrated that forskolin did not affect TRPV5 expression on the cell surface, suggesting that it alters the single-channel activity of a fixed number of TRPV5 channels. Application of the PKA catalytic subunit, which phosphorylated TRPV5, directly increased TRPV5 channel open probability. Alanine substitution of threonine-709 abolished both in vitro phosphorylation and PTH-mediated stimulation of TRPV5. In summary, PTH activates the cAMP-PKA signaling cascade, which rapidly phosphorylates threonine-709 of TRPV5, increasing the channel's open probability and promoting Ca(2+) reabsorption in the distal nephron.
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Affiliation(s)
- Theun de Groot
- Department of Physiology, Radboud University Nijmegen Medical Centre, Nijmegen, Netherlands
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Thyagarajan B, Benn BS, Christakos S, Rohacs T. Phospholipase C-mediated regulation of transient receptor potential vanilloid 6 channels: implications in active intestinal Ca2+ transport. Mol Pharmacol 2008; 75:608-16. [PMID: 19073818 DOI: 10.1124/mol.108.052449] [Citation(s) in RCA: 40] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022] Open
Abstract
Transient receptor potential vanilloid 6 (TRPV6) channels play an important role in intestinal Ca(2+) transport. These channels undergo Ca(2+)-induced inactivation. Here we show that Ca(2+) flowing through these channels activates phospholipase C (PLC) leading to the depletion of phosphatidylinositol 4,5-bisphosphate (PIP(2)) and formation of inositol 1,4,5-trisphosphate in TRPV6-expressing cells. PIP(2) depletion was inhibited by the two structurally different PLC inhibitors 1-[6-[[17beta-methoxyestra-1,3,5(10)-trien-17-yl]amino]hexyl]-1H-pyrrole-2,5-dione (U73122) and edelfosine. Ca(2+)-induced inactivation of TRPV6 was also prevented by the PLC inhibitors in whole-cell patch-clamp experiments. Ca(2+) signals in TRPV6-expressing cells were transient upon restoration of extracellular Ca(2+) but were rendered more sustained by the PLC inhibitors. Finally, intestinal Ca(2+) transport in the everted duodenal sac assay was enhanced by edelfosine. These observations suggest that Ca(2+)-induced inactivation of TRPV6 limits intestinal Ca(2+) absorption and raise the possibility that Ca(2+) absorption can be enhanced pharmacologically by interfering with PLC activation.
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Affiliation(s)
- Baskaran Thyagarajan
- Department of Pharmacology and Physiology, University of Medicine and Dentistry of New Jersey, New Jersey Medical School, Newark, New Jersey 07103, USA
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Lu P, Boros S, Chang Q, Bindels RJ, Hoenderop JG. The -glucuronidase klotho exclusively activates the epithelial Ca2+ channels TRPV5 and TRPV6. Nephrol Dial Transplant 2008; 23:3397-402. [DOI: 10.1093/ndt/gfn291] [Citation(s) in RCA: 83] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
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Pedersen SF, Owsianik G, Nilius B. TRP channels: an overview. Cell Calcium 2008; 38:233-52. [PMID: 16098585 DOI: 10.1016/j.ceca.2005.06.028] [Citation(s) in RCA: 544] [Impact Index Per Article: 34.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/20/2005] [Accepted: 06/28/2005] [Indexed: 12/12/2022]
Abstract
The TRP ("transient receptor potential") family of ion channels now comprises more than 30 cation channels, most of which are permeable for Ca2+, and some also for Mg2+. On the basis of sequence homology, the TRP family can be divided in seven main subfamilies: the TRPC ('Canonical') family, the TRPV ('Vanilloid') family, the TRPM ('Melastatin') family, the TRPP ('Polycystin') family, the TRPML ('Mucolipin') family, the TRPA ('Ankyrin') family, and the TRPN ('NOMPC') family. The cloning and characterization of members of this cation channel family has exploded during recent years, leading to a plethora of data on the roles of TRPs in a variety of tissues and species, including mammals, insects, and yeast. The present review summarizes the most pertinent recent evidence regarding the structural and functional properties of TRP channels, focusing on the regulation and physiology of mammalian TRPs.
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Affiliation(s)
- Stine Falsig Pedersen
- Department of Biochemistry, Institute for Molecular Biology and Physiology, University of Copenhagen, Denmark
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Identification of Nipsnap1 as a novel auxiliary protein inhibiting TRPV6 activity. Pflugers Arch 2008; 457:91-101. [DOI: 10.1007/s00424-008-0494-5] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/13/2008] [Accepted: 03/08/2008] [Indexed: 11/26/2022]
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Thyagarajan B, Lukacs V, Rohacs T. Hydrolysis of phosphatidylinositol 4,5-bisphosphate mediates calcium-induced inactivation of TRPV6 channels. J Biol Chem 2008; 283:14980-7. [PMID: 18390907 DOI: 10.1074/jbc.m704224200] [Citation(s) in RCA: 62] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/01/2023] Open
Abstract
TRPV6 is a member of the transient receptor potential superfamily of ion channels that facilitates Ca(2+) absorption in the intestines. These channels display high selectivity for Ca(2+), but in the absence of divalent cations they also conduct monovalent ions. TRPV6 channels have been shown to be inactivated by increased cytoplasmic Ca(2+) concentrations. Here we studied the mechanism of this Ca(2+)-induced inactivation. Monovalent currents through TRPV6 substantially decreased after a 40-s application of Ca(2+), but not Ba(2+). We also show that Ca(2+), but not Ba(2+), influx via TRPV6 induces depletion of phosphatidylinositol 4,5-bisphosphate (PI(4,5)P(2) or PIP(2)) and the formation of inositol 1,4,5-trisphosphate. Dialysis of DiC(8) PI(4,5)P(2) through the patch pipette inhibited Ca(2+)-dependent inactivation of TRPV6 currents in whole-cell patch clamp experiments. PI(4,5)P(2) also activated TRPV6 currents in excised patches. PI(4)P, the precursor of PI(4,5)P(2), neither activated TRPV6 in excised patches nor had any effect on Ca(2+)-induced inactivation in whole-cell experiments. Conversion of PI(4,5)P(2) to PI(4)P by a rapamycin-inducible PI(4,5)P(2) 5-phosphatase inhibited TRPV6 currents in whole-cell experiments. Inhibiting phosphatidylinositol 4 kinases with wortmannin decreased TRPV6 currents and Ca(2+) entry into TRPV6-expressing cells. We propose that Ca(2+) influx through TRPV6 activates phospholipase C and the resulting depletion of PI(4,5)P(2) contributes to the inactivation of TRPV6.
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Affiliation(s)
- Baskaran Thyagarajan
- Department of Pharmacology and Physiology, University of Medicine and Dentistry of New Jersey-New Jersey Medical School, 185 South Orange Avenue, Newark, NJ 07103, USA
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Hughes DA, Tang K, Strotmann R, Schöneberg T, Prenen J, Nilius B, Stoneking M. Parallel selection on TRPV6 in human populations. PLoS One 2008; 3:e1686. [PMID: 18301763 PMCID: PMC2246018 DOI: 10.1371/journal.pone.0001686] [Citation(s) in RCA: 37] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/24/2007] [Accepted: 01/25/2008] [Indexed: 12/25/2022] Open
Abstract
We identified and examined a candidate gene for local directional selection in Europeans, TRPV6, and conclude that selection has acted on standing genetic variation at this locus, creating parallel soft sweep events in humans. A novel modification of the extended haplotype homozygosity (EHH) test was utilized, which compares EHH for a single allele across populations, to investigate the signature of selection at TRPV6 and neighboring linked loci in published data sets for Europeans, Asians and African-Americans, as well as in newly-obtained sequence data for additional populations. We find that all non-African populations carry a signature of selection on the same haplotype at the TRPV6 locus. The selective footprints, however, are significantly differentiated between non-African populations and estimated to be younger than an ancestral population of non-Africans. The possibility of a single selection event occurring in an ancestral population of non-Africans was tested by simulations and rejected. The putatively-selected TRPV6 haplotype contains three candidate sites for functional differences, namely derived non-synonymous substitutions C157R, M378V and M681T. Potential functional differences between the ancestral and derived TRPV6 proteins were investigated by cloning the ancestral and derived forms, transfecting cell lines, and carrying out electrophysiology experiments via patch clamp analysis. No statistically-significant differences in biophysical channel function were found, although one property of the protein, namely Ca2+ dependent inactivation, may show functionally relevant differences between the ancestral and derived forms. Although the reason for selection on this locus remains elusive, this is the first demonstration of a widespread parallel selection event acting on standing genetic variation in humans, and highlights the utility of between population EHH statistics.
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Affiliation(s)
- David A Hughes
- Max Plank Institute for Evolutionary Anthropology, Leipzig, Germany.
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van de Graaf SFJ, Bindels RJM, Hoenderop JGJ. Physiology of epithelial Ca2+ and Mg2+ transport. Rev Physiol Biochem Pharmacol 2007; 158:77-160. [PMID: 17729442 DOI: 10.1007/112_2006_0607] [Citation(s) in RCA: 58] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
Ca2+ and Mg2+ are essential ions in a wide variety of cellular processes and form a major constituent of bone. It is, therefore, essential that the balance of these ions is strictly maintained. In the last decade, major breakthrough discoveries have vastly expanded our knowledge of the mechanisms underlying epithelial Ca2+ and Mg2+ transport. The genetic defects underlying various disorders with altered Ca2+ and/or Mg2+ handling have been determined. Recently, this yielded the molecular identification of TRPM6 as the gatekeeper of epithelial Mg2+ transport. Furthermore, expression cloning strategies have elucidated two novel members of the transient receptor potential family, TRPV5 and TRPV6, as pivotal ion channels determining transcellular Ca2+ transport. These two channels are regulated by a variety of factors, some historically strongly linked to Ca2+ homeostasis, others identified in a more serendipitous manner. Herein we review the processes of epithelial Ca2+ and Mg2+ transport, the molecular mechanisms involved, and the various forms of regulation.
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Affiliation(s)
- S F J van de Graaf
- Radboud University Nijmegen Medical Centre, 286 Cell Physiology, PO Box 9101, 6500 HB Nijmegen, The Netherlands
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Abstract
The ion channel TRPV6 is likely to function as an epithelial calcium channel in organs with high calcium transport requirements such as the intestine, kidney, and placenta. Transcriptional regulation of TRPV6 messenger RNA (mRNA) is controlled by 1,25-dihydroxyvitamin D, which is the active hormonal form of vitamin D3, and by additional calcium-dependent and vitamin D3-independent mechanisms. Under physiological conditions, the conductance of the channel itself is highly calcium-selective and underlies complex inactivation mechanisms triggered by intracellular calcium and magnesium ions. There is growing evidence that transcriptional regulation of TRPV6 in certain tissues undergoing malignant transformation, such as prostate cancer, is linked to cancer progression.
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Affiliation(s)
- U Wissenbach
- Experimentelle und Klinische Pharmakologie und Toxikologie, Medizinische Fakultät, Universität des Saarlandes, 66421 Homburg, Germany.
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Schoeber JP, Topala CN, Wang X, Diepens RJ, Lambers TT, Hoenderop JG, Bindels RJ. RGS2 Inhibits the Epithelial Ca2+ Channel TRPV6. J Biol Chem 2006; 281:29669-74. [PMID: 16895908 DOI: 10.1074/jbc.m606233200] [Citation(s) in RCA: 35] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/21/2023] Open
Abstract
The epithelial Ca(2+) channels TRPV5 and TRPV6 constitute the apical Ca(2+) entry pathway in the process of active Ca(2+) (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 G(alpha) subunits. Here we demonstrate that TRPV6 interacts with the NH(2)-terminal domain of RGS2 in a Ca(2+)-independent fashion and that overexpression of RGS2 reduces the Na(+) and Ca(2+) current of TRPV6 but not that of TRPV5-transfected human embryonic kidney 293 (HEK293) cells. In contrast, overexpression of the deletion mutant DeltaN-RGS2, lacking the NH(2)-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 G(alpha), did not affect RGS2 binding and electrophysiological properties of TRPV6, indicating a GPCR-independent mechanism of TRPV6 regulation by RGS2.
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Affiliation(s)
- Joost P Schoeber
- Department of Physiology, Nijmegen Centre for Molecular Life Sciences, Radboud University Nijmegen Medical Centre, Nijmegen 6500 HB, The Netherlands
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