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Cai R, Wang L, Liu X, Michalak M, Tang J, Peng JB, Chen XZ. Auto-inhibitory intramolecular S5/S6 interaction in the TRPV6 channel regulates breast cancer cell migration and invasion. Commun Biol 2021; 4:990. [PMID: 34413465 DOI: 10.1038/s42003-021-02521-3] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/19/2021] [Accepted: 08/04/2021] [Indexed: 11/09/2022] Open
Abstract
TRPV6, a Ca-selective channel, is abundantly expressed in the placenta, intestine, kidney and bone marrow. TRPV6 is vital to Ca homeostasis and its defective expression or function is linked to transient neonatal hyperparathyroidism, Lowe syndrome/Dent disease, renal stone, osteoporosis and cancers. The fact that the molecular mechanism underlying the function and regulation of TRPV6 is still not well understood hampers, in particular, the understanding of how TRPV6 contributes to breast cancer development. By electrophysiology and Ca imaging in Xenopus oocytes and cancer cells, molecular biology and numerical simulation, here we reveal an intramolecular S5/S6 helix interaction in TRPV6 that is functionally autoinhibitory and is mediated by the R532:D620 bonding. Predicted pathogenic mutation R532Q within S5 disrupts the S5/S6 interaction leading to gain-of-function of the channel, which promotes breast cancer cell progression through strengthening of the TRPV6/PI3K interaction, activation of a PI3K/Akt/GSK-3β cascade, and up-regulation of epithelial-mesenchymal transition and anti-apoptosis.
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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] [What about the content of this article? (0)] [Affiliation(s)] [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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3
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Cai R, Liu X, Zhang R, Hofmann L, Zheng W, Amin MR, Wang L, Hu Q, Peng JB, Michalak M, Flockerzi V, Ali DW, Chen XZ, Tang J. Autoinhibition of TRPV6 Channel and Regulation by PIP2. iScience 2020; 23:101444. [PMID: 32829285 PMCID: PMC7452202 DOI: 10.1016/j.isci.2020.101444] [Citation(s) in RCA: 17] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/28/2020] [Revised: 07/07/2020] [Accepted: 08/04/2020] [Indexed: 12/30/2022] Open
Abstract
Transient receptor potential vanilloid 6 (TRPV6), a calcium-selective channel possessing six transmembrane domains (S1-S6) and intracellular N and C termini, plays crucial roles in calcium absorption in epithelia and bone and is involved in human diseases including vitamin-D deficiency, osteoporosis, and cancer. The TRPV6 function and regulation remain poorly understood. Here we show that the TRPV6 intramolecular S4-S5 linker to C-terminal TRP helix (L/C) and N-terminal pre-S1 helix to TRP helix (N/C) interactions, mediated by Arg470:Trp593 and Trp321:Ile597 bonding, respectively, are autoinhibitory and are required for maintaining TRPV6 at basal states. Disruption of either interaction by mutations or blocking peptides activates TRPV6. The N/C interaction depends on the L/C interaction but not reversely. Three cationic residues in S5 or C terminus are involved in binding PIP2 to suppress both interactions thereby activating TRPV6. This study reveals "PIP2 - intramolecular interactions" regulatory mechanism of TRPV6 activation-autoinhibition, which will help elucidating the corresponding mechanisms in other TRP channels.
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Affiliation(s)
- Ruiqi Cai
- National “111” Center for Cellular Regulation and Molecular Pharmaceutics, Hubei University of Technology, Wuhan, Hubei 430068, China
- Membrane Protein Disease Research Group, Department of Physiology, Faculty of Medicine and Dentistry, University of Alberta, Edmonton, AB T6G 2H7, Canada
| | - Xiong Liu
- Membrane Protein Disease Research Group, Department of Physiology, Faculty of Medicine and Dentistry, University of Alberta, Edmonton, AB T6G 2H7, Canada
| | - Rui Zhang
- National “111” Center for Cellular Regulation and Molecular Pharmaceutics, Hubei University of Technology, Wuhan, Hubei 430068, China
| | - Laura Hofmann
- Experimentelle und Klinische Pharmakologie und Toxikologie, Universität des Saarlandes, 66421 Homburg, Germany
| | - Wang Zheng
- Membrane Protein Disease Research Group, Department of Physiology, Faculty of Medicine and Dentistry, University of Alberta, Edmonton, AB T6G 2H7, Canada
| | - Md Ruhul Amin
- Department of Biological Sciences, Biological Sciences Building, University of Alberta, T6G 2E9 Edmonton, AB, Canada
| | - Lingyun Wang
- Division of Nephrology, Department of Medicine, Nephrology Research and Training Center, University of Alabama at Birmingham, Birmingham, AL 35294, USA
| | - Qiaolin Hu
- Membrane Protein Disease Research Group, Department of Physiology, Faculty of Medicine and Dentistry, University of Alberta, Edmonton, AB T6G 2H7, Canada
| | - Ji-Bin Peng
- Division of Nephrology, Department of Medicine, Nephrology Research and Training Center, University of Alabama at Birmingham, Birmingham, AL 35294, USA
| | - Marek Michalak
- Membrane Protein Disease Research Group, Department of Biochemistry, Faculty of Medicine and Dentistry, University of Alberta, Edmonton, AB T6G 2H7, Canada
| | - Veit Flockerzi
- Experimentelle und Klinische Pharmakologie und Toxikologie, Universität des Saarlandes, 66421 Homburg, Germany
| | - Declan W. Ali
- Department of Biological Sciences, Biological Sciences Building, University of Alberta, T6G 2E9 Edmonton, AB, Canada
| | - Xing-Zhen Chen
- Membrane Protein Disease Research Group, Department of Physiology, Faculty of Medicine and Dentistry, University of Alberta, Edmonton, AB T6G 2H7, Canada
| | - Jingfeng Tang
- National “111” Center for Cellular Regulation and Molecular Pharmaceutics, Hubei University of Technology, Wuhan, Hubei 430068, China
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4
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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] [What about the content of this article? (0)] [Affiliation(s)] [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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McGoldrick LL, Singh AK, Saotome K, Yelshanskaya MV, Twomey EC, Grassucci RA, Sobolevsky AI. Opening of the human epithelial calcium channel TRPV6. Nature 2017; 553:233-237. [PMID: 29258289 PMCID: PMC5854407 DOI: 10.1038/nature25182] [Citation(s) in RCA: 148] [Impact Index Per Article: 21.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/14/2017] [Accepted: 11/28/2017] [Indexed: 12/18/2022]
Abstract
Ca2+-selective transient receptor potential vanilloid subfamily member 6 (TRPV6) channels play a critical role in calcium uptake in epithelial tissues1–4. Altered TRPV6 expression is associated with a variety of human diseases5, including cancers6. TRPV6 channels are constitutively active1,7,8 and their open probability depends on the lipidic composition of the membrane, increasing significantly in the presence of phosphatidylinositol 4,5-bisphosphate (PIP2)7,9. We previously solved crystal structures of detergent-solubilized rat TRPV6 in the closed state10,11. Corroborating previous electrophysiological studies3, these structures demonstrated that the Ca2+ selectivity of TRPV6 arises from a ring of aspartate side chains in the selectivity filter that tightly binds Ca2+. However, it has remained unknown how TRPV6 channels open and close their pores for ion permeation. Here we present cryo-EM structures of human TRPV6 in the open and closed states. The channel selectivity filter adopts similar conformations in both states, consistent with its explicit role in ion permeation. The iris-like channel opening is accompanied by an α-to-π helical transition in the pore-lining S6 helices at an alanine hinge just below the selectivity filter. As a result of this transition, the S6 helices bend and rotate, exposing different residues to the ion channel pore in the open and closed states. This novel gating mechanism, which defines the constitutive activity of TRPV6, is unique for tetrameric ion channels and provides new structural insights for understanding their diverse roles in physiology and disease.
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Affiliation(s)
- Luke L McGoldrick
- Department of Biochemistry and Molecular Biophysics, Columbia University, 650 West 168th Street, New York, New York 10032, USA.,Integrated Program in Cellular, Molecular, and Biomedical Studies, Columbia University, 650 West 168th Street, New York, New York 10032, USA
| | - Appu K Singh
- Department of Biochemistry and Molecular Biophysics, Columbia University, 650 West 168th Street, New York, New York 10032, USA
| | - Kei Saotome
- Department of Biochemistry and Molecular Biophysics, Columbia University, 650 West 168th Street, New York, New York 10032, USA
| | - Maria V Yelshanskaya
- Department of Biochemistry and Molecular Biophysics, Columbia University, 650 West 168th Street, New York, New York 10032, USA
| | - Edward C Twomey
- Department of Biochemistry and Molecular Biophysics, Columbia University, 650 West 168th Street, New York, New York 10032, USA.,Integrated Program in Cellular, Molecular, and Biomedical Studies, Columbia University, 650 West 168th Street, New York, New York 10032, USA
| | - Robert A Grassucci
- Department of Biochemistry and Molecular Biophysics, Columbia University, 650 West 168th Street, New York, New York 10032, USA
| | - Alexander I Sobolevsky
- Department of Biochemistry and Molecular Biophysics, Columbia University, 650 West 168th Street, New York, New York 10032, USA
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6
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Choy CH, Han BK, Botelho RJ. Phosphoinositide Diversity, Distribution, and Effector Function: Stepping Out of the Box. Bioessays 2017; 39. [PMID: 28977683 DOI: 10.1002/bies.201700121] [Citation(s) in RCA: 31] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/07/2017] [Revised: 08/31/2017] [Indexed: 12/26/2022]
Abstract
Phosphoinositides (PtdInsPs) modulate a plethora of functions including signal transduction and membrane trafficking. PtdInsPs are thought to consist of seven interconvertible species that localize to a specific organelle, to which they recruit a set of cognate effector proteins. Here, in reviewing the literature, we argue that this model needs revision. First, PtdInsPs can carry a variety of acyl chains, greatly boosting their molecular diversity. Second, PtdInsPs are more promiscuous in their localization than is usually acknowledged. Third, PtdInsP interconversion is likely achieved through kinase-phosphatase enzyme complexes that coordinate their activities and channel substrates without affecting bulk substrate population. Additionally, we contend that despite hundreds of PtdInsP effectors, our attention is biased toward few proteins. Lastly, we recognize that PtdInsPs can act to nucleate coincidence detection at the effector level, as in PDK1 and Akt. Overall, better integrated models of PtdInsP regulation and function are not only possible but needed.
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Affiliation(s)
- Christopher H Choy
- Graduate Program in Molecular Science, Ryerson University, Toronto, ON, Canada M5B2K3.,Department of Chemistry and Biology, Ryerson University, Toronto, ON, Canada M5B2K3
| | - Bong-Kwan Han
- The Intelligent Synthetic Biology Center, Korea Advanced Institute of Science and Technology, Daejeon 34141, South Korea
| | - Roberto J Botelho
- Graduate Program in Molecular Science, Ryerson University, Toronto, ON, Canada M5B2K3.,Department of Chemistry and Biology, Ryerson University, Toronto, ON, Canada M5B2K3
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