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Ponce A, Larre I, Jimenez L, Roldán ML, Shoshani L, Cereijido M. Ouabain's Influence on TRPV4 Channels of Epithelial Cells: An Exploration of TRPV4 Activity, Expression, and Signaling Pathways. Int J Mol Sci 2023; 24:16687. [PMID: 38069012 PMCID: PMC10705919 DOI: 10.3390/ijms242316687] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/06/2023] [Revised: 11/16/2023] [Accepted: 11/21/2023] [Indexed: 12/18/2023] Open
Abstract
Ouabain, a substance originally obtained from plants, is now classified as a hormone because it is produced endogenously in certain animals, including humans. However, its precise effects on the body remain largely unknown. Previous studies have shown that ouabain can influence the phenotype of epithelial cells by affecting the expression of cell-cell molecular components and voltage-gated potassium channels. In this study, we conducted whole-cell clamp assays to determine whether ouabain affects the activity and/or expression of TRPV4 channels. Our findings indicate that ouabain has a statistically significant effect on the density of TRPV4 currents (dITRPV4), with an EC50 of 1.89 nM. Regarding treatment duration, dITRPV4 reaches its peak at around 1 h, followed by a subsequent decline and then a resurgence after 6 h, suggesting a short-term modulatory effect related to on TRPV4 channel activity and a long-term effect related to the promotion of synthesis of new TRPV4 channel units. The enhancement of dITRPV4 induced by ouabain was significantly lower in cells seeded at low density than in cells in a confluent monolayer, indicating that the action of ouabain depends on intercellular contacts. Furthermore, the fact that U73122 and neomycin suppress the effect caused by ouabain in the short term suggests that the short-term induced enhancement of dITRPV4 is due to the depletion of PIP2 stores. In contrast, the fact that the long-term effect is inhibited by PP2, wortmannin, PD, FR18, and IKK16 suggests that cSrc, PI3K, Erk1/2, and NF-kB are among the components included in the signaling pathways.
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Affiliation(s)
- Arturo Ponce
- Department of Physiology, Biophysics and Neurosciences, CINVESTAV-IPN, Mexico City 07360, Mexico; (L.J.); (M.L.R.); (L.S.); (M.C.)
| | - Isabel Larre
- Department of Physiology, Faculty of Medicine, Universidad Nacional Autónoma de Mexico (UNAM), Mexico City 04510, Mexico;
- Department of Clinical and Translational Science, Joan C. Edwards School of Medicine, Marshall University, Huntington, WV 25755, USA
| | - Lidia Jimenez
- Department of Physiology, Biophysics and Neurosciences, CINVESTAV-IPN, Mexico City 07360, Mexico; (L.J.); (M.L.R.); (L.S.); (M.C.)
| | - Maria Luisa Roldán
- Department of Physiology, Biophysics and Neurosciences, CINVESTAV-IPN, Mexico City 07360, Mexico; (L.J.); (M.L.R.); (L.S.); (M.C.)
| | - Liora Shoshani
- Department of Physiology, Biophysics and Neurosciences, CINVESTAV-IPN, Mexico City 07360, Mexico; (L.J.); (M.L.R.); (L.S.); (M.C.)
| | - Marcelino Cereijido
- Department of Physiology, Biophysics and Neurosciences, CINVESTAV-IPN, Mexico City 07360, Mexico; (L.J.); (M.L.R.); (L.S.); (M.C.)
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Stavniichuk A, Pyrshev K, Zaika O, Tomilin VN, Kordysh M, Lakk M, Križaj D, Pochynyuk O. TRPV4 expression in the renal tubule is necessary for maintaining whole body K + homeostasis. Am J Physiol Renal Physiol 2023; 324:F603-F616. [PMID: 37141145 PMCID: PMC10281785 DOI: 10.1152/ajprenal.00278.2022] [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] [Received: 11/11/2022] [Revised: 04/26/2023] [Accepted: 04/30/2023] [Indexed: 05/05/2023] Open
Abstract
The Ca2+-permeable transient receptor potential vanilloid type 4 (TRPV4) channel serves as the sensor of tubular flow, thus being well suited to govern mechanosensitive K+ transport in the distal renal tubule. Here, we directly tested whether the TRPV4 function is significant in affecting K+ balance. We used balance metabolic cage experiments and systemic measurements with different K+ feeding regimens [high (5% K+), regular (0.9% K+), and low (<0.01% K+)] in newly created transgenic mice with selective TRPV4 deletion in the renal tubule (TRPV4fl/fl-Pax8Cre) and their littermate controls (TRPV4fl/fl). Deletion was verified by the absence of TRPV4 protein expression and lack of TRPV4-dependent Ca2+ influx. There were no differences in plasma electrolytes, urinary volume, and K+ levels at baseline. In contrast, plasma K+ levels were significantly elevated in TRPV4fl/fl-Pax8Cre mice on high K+ intake. K+-loaded knockout mice exhibited lower urinary K+ levels than TRPV4fl/fl mice, which was accompanied by higher aldosterone levels by day 7. Moreover, TRPV4fl/fl-Pax8Cre mice had more efficient renal K+ conservation and higher plasma K+ levels in the state of dietary K+ deficiency. H+-K+-ATPase levels were significantly increased in TRPV4fl/fl-Pax8Cre mice on a regular diet and especially on a low-K+ diet, pointing to augmented K+ reabsorption in the collecting duct. Consistently, we found a significantly faster intracellular pH recovery after intracellular acidification, as an index of H+-K+-ATPase activity, in split-opened collecting ducts from TRPV4fl/fl-Pax8Cre mice. In summary, our results demonstrate an indispensable prokaliuretic role of TRPV4 in the renal tubule in controlling K+ balance and urinary K+ excretion during variations in dietary K+ intake. NEW & NOTEWORTHY The mechanoactivated transient receptor potential vanilloid type 4 (TRPV4) channel is expressed in distal tubule segments, where it controls flow-dependent K+ transport. Global TRPV4 deficiency causes impaired adaptation to variations in dietary K+ intake. Here, we demonstrate that renal tubule-specific TRPV4 deletion is sufficient to recapitulate the phenotype by causing antikaliuresis and higher plasma K+ levels in both states of K+ load and deficiency.
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Affiliation(s)
- Anna Stavniichuk
- Department of Integrative Biology and Pharmacology, The University of Texas Health Science Center, Houston, Texas, United States
| | - Kyrylo Pyrshev
- Department of Integrative Biology and Pharmacology, The University of Texas Health Science Center, Houston, Texas, United States
| | - Oleg Zaika
- Department of Integrative Biology and Pharmacology, The University of Texas Health Science Center, Houston, Texas, United States
| | - Viktor N Tomilin
- Department of Integrative Biology and Pharmacology, The University of Texas Health Science Center, Houston, Texas, United States
| | - Mariya Kordysh
- Department of Integrative Biology and Pharmacology, The University of Texas Health Science Center, Houston, Texas, United States
| | - Monika Lakk
- Department of Ophthalmology and Visual Sciences, University of Utah School of Medicine, Salt Lake City, Utah, United States
| | - David Križaj
- Department of Ophthalmology and Visual Sciences, University of Utah School of Medicine, Salt Lake City, Utah, United States
| | - Oleh Pochynyuk
- Department of Integrative Biology and Pharmacology, The University of Texas Health Science Center, Houston, Texas, United States
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Carrisoza-Gaytan R, Kroll KT, Hiratsuka K, Gupta NR, Morizane R, Lewis JA, Satlin LM. Functional maturation of kidney organoid tubules: PIEZO1-mediated Ca 2+ signaling. Am J Physiol Cell Physiol 2023; 324:C757-C768. [PMID: 36745528 PMCID: PMC10027089 DOI: 10.1152/ajpcell.00288.2022] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2022] [Revised: 01/25/2023] [Accepted: 01/26/2023] [Indexed: 02/07/2023]
Abstract
Kidney organoids cultured on adherent matrices in the presence of superfusate flow generate vascular networks and exhibit more mature podocyte and tubular compartments compared with static controls (Homan KA, Gupta N, Kroll KT, Kolesky DB, Skylar-Scott M, Miyoshi T, Mau D, Valerius MT, Ferrante T, Bonventre JV, Lewis JA, Morizane R. Nat Methods 16: 255-262, 2019; Takasato M, Er PX, Chiu HS, Maier B, Baillie GJ, Ferguson C, Parton RG, Wolvetang EJ, Roost MS, Chuva de Sousa Lopes SM, Little MH. Nature 526: 564-568, 2015.). However, their physiological function has yet to be systematically investigated. Here, we measured mechano-induced changes in intracellular Ca2+ concentration ([Ca2+]i) in tubules isolated from organoids cultured for 21-64 days, microperfused in vitro or affixed to the base of a specimen chamber, and loaded with fura-2 to measure [Ca2+]i. A rapid >2.5-fold increase in [Ca2+]i from a baseline of 195.0 ± 22.1 nM (n = 9; P ≤ 0.001) was observed when microperfused tubules from organoids >40 days in culture were subjected to luminal flow. In contrast, no response was detected in tubules isolated from organoids <30 days in culture. Nonperfused tubules (41 days) subjected to a 10-fold increase in bath flow rate also exhibited a threefold increase in [Ca2+]i from baseline (P < 0.001). Mechanosensitive PIEZO1 channels contribute to the flow-induced [Ca2+]i response in mouse distal tubule (Carrisoza-Gaytan R, Dalghi MG, Apodaca GL, Kleyman TR, Satlin LM. The FASEB J 33: 824.25, 2019.). Immunodetectable apical and basolateral PIEZO1 was identified in tubular structures by 21 days in culture. Basolateral PIEZO1 appeared to be functional as basolateral exposure of nonperfused tubules to the PIEZO1 activator Yoda 1 increased [Ca2+]i (P ≤ 0.001) in segments from organoids cultured for >30 days, with peak [Ca2+]i increasing with advancing days in culture. These results are consistent with a maturational increase in number and/or activity of flow/stretch-sensitive Ca2+ channels, including PIEZO1, in tubules of static organoids in culture.
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Affiliation(s)
- Rolando Carrisoza-Gaytan
- Department of Pediatrics, Icahn School of Medicine at Mount Sinai, New York, New York, United States
| | - Katharina T Kroll
- Paulson School of Engineering and Applied Sciences, Wyss Institute for Biologically Inspired Engineering, Harvard University, Cambridge, Massachusetts, United States
| | - Ken Hiratsuka
- Paulson School of Engineering and Applied Sciences, Wyss Institute for Biologically Inspired Engineering, Harvard University, Cambridge, Massachusetts, United States
- Nephrology Division, Massachusetts General Hospital, Boston, Massachusetts, United States
- Department of Medicine, Harvard Medical School, Boston, Massachusetts, United States
| | - Navin R Gupta
- Nephrology Division, Massachusetts General Hospital, Boston, Massachusetts, United States
- Department of Medicine, Harvard Medical School, Boston, Massachusetts, United States
| | - Ryuji Morizane
- Paulson School of Engineering and Applied Sciences, Wyss Institute for Biologically Inspired Engineering, Harvard University, Cambridge, Massachusetts, United States
- Nephrology Division, Massachusetts General Hospital, Boston, Massachusetts, United States
- Department of Medicine, Harvard Medical School, Boston, Massachusetts, United States
- Harvard Stem Cell Institute, Cambridge, Massachusetts, United States
| | - Jennifer A Lewis
- Paulson School of Engineering and Applied Sciences, Wyss Institute for Biologically Inspired Engineering, Harvard University, Cambridge, Massachusetts, United States
- Harvard Stem Cell Institute, Cambridge, Massachusetts, United States
| | - Lisa M Satlin
- Department of Pediatrics, Icahn School of Medicine at Mount Sinai, New York, New York, United States
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Ma Q, Miri Z, Haugen HJ, Moghanian A, Loca D. Significance of mechanical loading in bone fracture healing, bone regeneration, and vascularization. J Tissue Eng 2023; 14:20417314231172573. [PMID: 37251734 PMCID: PMC10214107 DOI: 10.1177/20417314231172573] [Citation(s) in RCA: 6] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/02/2023] [Accepted: 04/13/2023] [Indexed: 05/31/2023] Open
Abstract
In 1892, J.L. Wolff proposed that bone could respond to mechanical and biophysical stimuli as a dynamic organ. This theory presents a unique opportunity for investigations on bone and its potential to aid in tissue repair. Routine activities such as exercise or machinery application can exert mechanical loads on bone. Previous research has demonstrated that mechanical loading can affect the differentiation and development of mesenchymal tissue. However, the extent to which mechanical stimulation can help repair or generate bone tissue and the related mechanisms remain unclear. Four key cell types in bone tissue, including osteoblasts, osteoclasts, bone lining cells, and osteocytes, play critical roles in responding to mechanical stimuli, while other cell lineages such as myocytes, platelets, fibroblasts, endothelial cells, and chondrocytes also exhibit mechanosensitivity. Mechanical loading can regulate the biological functions of bone tissue through the mechanosensor of bone cells intraosseously, making it a potential target for fracture healing and bone regeneration. This review aims to clarify these issues and explain bone remodeling, structure dynamics, and mechano-transduction processes in response to mechanical loading. Loading of different magnitudes, frequencies, and types, such as dynamic versus static loads, are analyzed to determine the effects of mechanical stimulation on bone tissue structure and cellular function. Finally, the importance of vascularization in nutrient supply for bone healing and regeneration was further discussed.
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Affiliation(s)
- Qianli Ma
- Department of Biomaterials, Institute
of Clinical Dentistry, University of Oslo, Norway
- Department of Immunology, School of
Basic Medicine, Fourth Military Medical University, Xi’an, PR China
| | - Zahra Miri
- Department of Materials Engineering,
Isfahan University of Technology, Isfahan, Iran
| | - Håvard Jostein Haugen
- Department of Biomaterials, Institute
of Clinical Dentistry, University of Oslo, Norway
| | - Amirhossein Moghanian
- Department of Materials Engineering,
Imam Khomeini International University, Qazvin, Iran
| | - Dagnjia Loca
- Rudolfs Cimdins Riga Biomaterials
Innovations and Development Centre, Institute of General Chemical Engineering,
Faculty of Materials Science and Applied Chemistry, Riga Technical University, Riga,
Latvia
- Baltic Biomaterials Centre of
Excellence, Headquarters at Riga Technical University, Riga, Latvia
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Kleene SJ. Regenerative Calcium Currents in Renal Primary Cilia. Front Physiol 2022; 13:894518. [PMID: 35620606 PMCID: PMC9127361 DOI: 10.3389/fphys.2022.894518] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/11/2022] [Accepted: 04/18/2022] [Indexed: 11/13/2022] Open
Abstract
Polycystic kidney disease (PKD) is a leading cause of end-stage renal disease. PKD arises from mutations in proteins, one a Ca2+-conducting channel, expressed in the primary cilia of renal epithelial cells. A common hypothesis is that Ca2+ entering through ciliary ion channels may reduce cystogenesis. The cilia have at least two Ca2+-conducting channels: polycystin-2 (PC2) and TRPV4 (transient receptor potential (TRP) cation channel, subfamily V, member 4), but how substantially they can increase intraciliary Ca2+ is unknown. By recording channel activities in isolated cilia, conditions are identified under which the channels can increase free Ca2+ within the cilium by at least 500-fold through regenerative (positive-feedback) signaling. Ca2+ that has entered through a channel can activate the channel internally, which increases the Ca2+ influx, and so on. Regenerative signaling is favored when the concentration of the Ca2+ buffer is reduced or when a slower buffer is used. Under such conditions, the Ca2+ that enters the cilium through a single PC2 channel is sufficient to almost fully activate that same channel. Regenerative signaling is not detectable with reduced external Ca2+. Reduced buffering also allows regenerative signaling through TRPV4 channels, but not through TRPM4 (TRP subfamily M, member 4) channels, which are activated by Ca2+ but do not conduct it. On a larger scale, Ca2+ that enters through TRPV4 channels can cause secondary activation of PC2 channels. I discuss the likelihood of regenerative ciliary Ca2+ signaling in vivo, a possible mechanism for its activation, and how it might relate to cystogenesis.
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Affiliation(s)
- Steven J. Kleene
- Department of Pharmacology and Systems Physiology, University of Cincinnati, Cincinnati, OH, United States
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6
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Mechanical regulation of bone remodeling. Bone Res 2022; 10:16. [PMID: 35181672 PMCID: PMC8857305 DOI: 10.1038/s41413-022-00190-4] [Citation(s) in RCA: 134] [Impact Index Per Article: 67.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/14/2021] [Revised: 11/04/2021] [Accepted: 12/13/2021] [Indexed: 12/17/2022] Open
Abstract
Bone remodeling is a lifelong process that gives rise to a mature, dynamic bone structure via a balance between bone formation by osteoblasts and resorption by osteoclasts. These opposite processes allow the accommodation of bones to dynamic mechanical forces, altering bone mass in response to changing conditions. Mechanical forces are indispensable for bone homeostasis; skeletal formation, resorption, and adaptation are dependent on mechanical signals, and loss of mechanical stimulation can therefore significantly weaken the bone structure, causing disuse osteoporosis and increasing the risk of fracture. The exact mechanisms by which the body senses and transduces mechanical forces to regulate bone remodeling have long been an active area of study among researchers and clinicians. Such research will lead to a deeper understanding of bone disorders and identify new strategies for skeletal rejuvenation. Here, we will discuss the mechanical properties, mechanosensitive cell populations, and mechanotransducive signaling pathways of the skeletal system.
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Bothwell SW, Omileke D, Patabendige A, Spratt NJ. CSF Secretion Is Not Altered by NKCC1 Nor TRPV4 Antagonism in Healthy Rats. Brain Sci 2021; 11:brainsci11091117. [PMID: 34573139 PMCID: PMC8471756 DOI: 10.3390/brainsci11091117] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/04/2021] [Revised: 08/20/2021] [Accepted: 08/22/2021] [Indexed: 11/16/2022] Open
Abstract
Background: Cerebrospinal fluid (CSF) secretion can be targeted to reduce elevated intracranial pressure (ICP). Sodium-potassium-chloride cotransporter 1 (NKCC1) antagonism is used clinically. However, supporting evidence is limited. The transient receptor potential vanilloid-4 (TRPV4) channel may also regulate CSF secretion and ICP elevation. We investigated whether antagonism of these proteins reduces CSF secretion. Methods: We quantified CSF secretion rates in male Wistar rats. The cerebral aqueduct was blocked with viscous mineral oil, and a lateral ventricle was cannulated. Secretion rate was measured at baseline and after antagonist administration. Acetazolamide was administered as a positive control to confirm changes in CSF secretion rates. Results: Neither NKCC1, nor TRPV4 antagonism altered CSF secretion rate from baseline, n = 3, t(2) = 1.14, p = 0.37, and n = 4, t(3) = 0.58, p = 0.6, respectively. Acetazolamide reduced CSF secretion by ~50% across all groups, n = 7, t(6) = 4.294, p = 0.005. Conclusions: Acute antagonism of NKCC1 and TRPV4 proteins at the choroid plexus does not reduce CSF secretion in healthy rats. Further investigation of protein changes and antagonism should be explored in neurological disease where increased CSF secretion and ICP are observed before discounting the therapeutic potential of protein antagonism at these sites.
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Affiliation(s)
- Steven W. Bothwell
- The School of Biomedical Sciences and Pharmacy, The University of Newcastle, Callaghan, NSW 2308, Australia; (S.W.B.); (D.O.)
- Hunter Medical Research Institute, New Lambton Heights, NSW 2305, Australia
| | - Daniel Omileke
- The School of Biomedical Sciences and Pharmacy, The University of Newcastle, Callaghan, NSW 2308, Australia; (S.W.B.); (D.O.)
- Hunter Medical Research Institute, New Lambton Heights, NSW 2305, Australia
| | - Adjanie Patabendige
- The School of Biomedical Sciences and Pharmacy, The University of Newcastle, Callaghan, NSW 2308, Australia; (S.W.B.); (D.O.)
- Hunter Medical Research Institute, New Lambton Heights, NSW 2305, Australia
- Institute of Infection, Veterinary & Ecological Sciences, University of Liverpool, Wirral CH64 7TE, UK
- Correspondence: (A.P.); (N.J.S.)
| | - Neil J. Spratt
- The School of Biomedical Sciences and Pharmacy, The University of Newcastle, Callaghan, NSW 2308, Australia; (S.W.B.); (D.O.)
- Hunter Medical Research Institute, New Lambton Heights, NSW 2305, Australia
- Hunter New England Local Health District, New Lambton Heights, NSW 2305, Australia
- Correspondence: (A.P.); (N.J.S.)
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Kärki T, Tojkander S. TRPV Protein Family-From Mechanosensing to Cancer Invasion. Biomolecules 2021; 11:1019. [PMID: 34356643 PMCID: PMC8301805 DOI: 10.3390/biom11071019] [Citation(s) in RCA: 26] [Impact Index Per Article: 8.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/08/2021] [Revised: 06/30/2021] [Accepted: 07/09/2021] [Indexed: 02/08/2023] Open
Abstract
Biophysical cues from the cellular microenvironment are detected by mechanosensitive machineries that translate physical signals into biochemical signaling cascades. At the crossroads of extracellular space and cell interior are located several ion channel families, including TRP family proteins, that are triggered by mechanical stimuli and drive intracellular signaling pathways through spatio-temporally controlled Ca2+-influx. Mechanosensitive Ca2+-channels, therefore, act as critical components in the rapid transmission of physical signals into biologically compatible information to impact crucial processes during development, morphogenesis and regeneration. Given the mechanosensitive nature of many of the TRP family channels, they must also respond to the biophysical changes along the development of several pathophysiological conditions and have also been linked to cancer progression. In this review, we will focus on the TRPV, vanilloid family of TRP proteins, and their connection to cancer progression through their mechanosensitive nature.
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Affiliation(s)
- Tytti Kärki
- Department of Applied Physics, School of Science, Aalto University, 00076 Espoo, Finland;
| | - Sari Tojkander
- Department of Veterinary Biosciences, Section of Pathology, University of Helsinki, 00014 Helsinki, Finland
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10
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Liu N, Yan F, Ma Q, Zhao J. Modulation of TRPV4 and BKCa for treatment of brain diseases. Bioorg Med Chem 2020; 28:115609. [PMID: 32690264 DOI: 10.1016/j.bmc.2020.115609] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/26/2020] [Revised: 06/19/2020] [Accepted: 06/23/2020] [Indexed: 12/22/2022]
Abstract
As a member of transient receptor potential family, the transient receptor potential vanilloid 4 (TRPV4) is a kind of nonselective calcium-permeable cation channel, which belongs to non-voltage gated Ca2+ channel. Large-conductance Ca2+-activated K+ channel (BKCa) represents a unique superfamily of Ca2+-activated K+ channel (KCa) that is both voltage and intracellular Ca2+ dependent. Not surprisingly, aberrant function of either TRPV4 or BKCa in neurons has been associated with brain disorders, such as Alzheimer's disease, cerebral ischemia, brain tumor, epilepsy, as well as headache. In these diseases, vascular dysfunction is a common characteristic. Notably, endothelial and smooth muscle TRPV4 can mediate BKCa to regulate cerebral blood flow and pressure. Therefore, in this review, we not only discuss the diverse functions of TRPV4 and BKCa in neurons to integrate relative signaling pathways in the context of cerebral physiological and pathological situations respectively, but also reveal the relationship between TRPV4 and BKCa in regulation of cerebral vascular tone as an etiologic factor. Based on these analyses, this review demonstrates the effective mechanisms of compounds targeting these two channels, which may be potential therapeutic strategies for diseases in the brain.
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Affiliation(s)
- Na Liu
- Faculty of Life Science and Technology, Kunming University of Science and Technology, Kunming 650500, PR China; Department of Anesthesiology, The Affiliated Hospital of Kunming University of Science and Technology, Kunming 650032, PR China
| | - Fang Yan
- Medical School, Kunming University of Science and Technology, Kunming 650500, PR China
| | - Qingjie Ma
- Department of Anesthesiology, The Affiliated Hospital of Kunming University of Science and Technology, Kunming 650032, PR China
| | - Jianhua Zhao
- Department of Neurosurgery, The Affiliated Hospital of Kunming University of Science and Technology, Kunming 650032, PR China.
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Daems M, Peacock HM, Jones EAV. Fluid flow as a driver of embryonic morphogenesis. Development 2020; 147:147/15/dev185579. [PMID: 32769200 DOI: 10.1242/dev.185579] [Citation(s) in RCA: 19] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
Fluid flow is a powerful morphogenic force during embryonic development. The physical forces created by flowing fluids can either create morphogen gradients or be translated by mechanosensitive cells into biological changes in gene expression. In this Primer, we describe how fluid flow is created in different systems and highlight the important mechanosensitive signalling pathways involved for sensing and transducing flow during embryogenesis. Specifically, we describe how fluid flow helps establish left-right asymmetry in the early embryo and discuss the role of flow of blood, lymph and cerebrospinal fluid in sculpting the embryonic cardiovascular and nervous system.
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Affiliation(s)
- Margo Daems
- Department of Cardiovascular Sciences, Centre for Molecular and Vascular Biology, KU Leuven, 3000 Leuven, Belgium
| | - Hanna M Peacock
- Department of Cardiovascular Sciences, Centre for Molecular and Vascular Biology, KU Leuven, 3000 Leuven, Belgium
| | - Elizabeth A V Jones
- Department of Cardiovascular Sciences, Centre for Molecular and Vascular Biology, KU Leuven, 3000 Leuven, Belgium
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12
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Swain SM, Romac JMJ, Shahid RA, Pandol SJ, Liedtke W, Vigna SR, Liddle RA. TRPV4 channel opening mediates pressure-induced pancreatitis initiated by Piezo1 activation. J Clin Invest 2020; 130:2527-2541. [PMID: 31999644 PMCID: PMC7190979 DOI: 10.1172/jci134111] [Citation(s) in RCA: 114] [Impact Index Per Article: 28.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/07/2019] [Accepted: 01/23/2020] [Indexed: 12/24/2022] Open
Abstract
Elevated pressure in the pancreatic gland is the central cause of pancreatitis following abdominal trauma, surgery, endoscopic retrograde cholangiopancreatography, and gallstones. In the pancreas, excessive intracellular calcium causes mitochondrial dysfunction, premature zymogen activation, and necrosis, ultimately leading to pancreatitis. Although stimulation of the mechanically activated, calcium-permeable ion channel Piezo1 in the pancreatic acinar cell is the initial step in pressure-induced pancreatitis, activation of Piezo1 produces only transient elevation in intracellular calcium that is insufficient to cause pancreatitis. Therefore, how pressure produces a prolonged calcium elevation necessary to induce pancreatitis is unknown. We demonstrate that Piezo1 activation in pancreatic acinar cells caused a prolonged elevation in intracellular calcium levels, mitochondrial depolarization, intracellular trypsin activation, and cell death. Notably, these effects were dependent on the degree and duration of force applied to the cell. Low or transient force was insufficient to activate these pathological changes, whereas higher and prolonged application of force triggered sustained elevation in intracellular calcium, leading to enzyme activation and cell death. All of these pathological events were rescued in acinar cells treated with a Piezo1 antagonist and in acinar cells from mice with genetic deletion of Piezo1. We discovered that Piezo1 stimulation triggered transient receptor potential vanilloid subfamily 4 (TRPV4) channel opening, which was responsible for the sustained elevation in intracellular calcium that caused intracellular organelle dysfunction. Moreover, TRPV4 gene-KO mice were protected from Piezo1 agonist- and pressure-induced pancreatitis. These studies unveil a calcium signaling pathway in which a Piezo1-induced TRPV4 channel opening causes pancreatitis.
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Affiliation(s)
- Sandip M. Swain
- Department of Medicine, Duke University, Durham, North Carolina, USA
| | | | - Rafiq A. Shahid
- Department of Medicine, Duke University, Durham, North Carolina, USA
| | | | | | - Steven R. Vigna
- Department of Medicine, Duke University, Durham, North Carolina, USA
- Department of Cell Biology, Duke University, Durham, North Carolina, USA
| | - Rodger A. Liddle
- Department of Medicine, Duke University, Durham, North Carolina, USA
- Department of Veterans Affairs Health Care System, Durham, North Carolina, USA
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13
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Tomilin V, Mamenko M, Zaika O, Wingo CS, Pochynyuk O. TRPV4 deletion protects against hypokalemia during systemic K + deficiency. Am J Physiol Renal Physiol 2019; 316:F948-F956. [PMID: 30838874 DOI: 10.1152/ajprenal.00043.2019] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022] Open
Abstract
Tight regulation of K+ balance is fundamental for normal physiology. Reduced dietary K+ intake, which is common in Western diets, often leads to hypokalemia and associated cardiovascular- and kidney-related pathologies. The distal nephron, and, specifically, the collecting duct (CD), is the major site of controlled K+ reabsorption via H+-K+-ATPase in the state of dietary K+ deficiency. We (Mamenko MV, Boukelmoune N, Tomilin VN, Zaika OL, Jensen VB, O'Neil RG, Pochynyuk OM. Kidney Int 91: 1398-1409, 2017) have previously demonstrated that the transient receptor potential vanilloid type 4 (TRPV4) Ca2+ channel, abundantly expressed in the CD, contributes to renal K+ handling by promoting flow-induced K+ secretion. Here, we investigated a potential role of TRPV4 in controlling H+-K+-ATPase-dependent K+ reabsorption in the CD. Treatment with a K+-deficient diet (<0.01% K+) for 7 days reduced serum K+ levels in wild-type (WT) mice from 4.3 ± 0.2 to 3.3 ± 0.2 mM but not in TRPV4-/- mice (4.3 ± 0.1 and 4.2 ± 0.3 mM, respectively). Furthermore, we detected a significant reduction in 24-h urinary K+ levels in TRPV4-/- compared with WT mice upon switching to K+-deficient diet. TRPV4-/- animals also had significantly more acidic urine on a low-K+ diet, but not on a regular (0.9% K+) or high-K+ (5% K+) diet, which is consistent with increased H+-K+-ATPase activity. Moreover, we detected a greatly accelerated H+-K+-ATPase-dependent intracellular pH extrusion in freshly isolated CDs from TRPV4-/- compared with WT mice fed a K+-deficient diet. Overall, our results demonstrate a novel kaliuretic role of TRPV4 by inhibiting H+-K+-ATPase-dependent K+ reabsorption in the CD. We propose that TRPV4 inhibition could be a novel strategy to manage certain hypokalemic states in clinical settings.
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Affiliation(s)
- Viktor Tomilin
- Department of Integrative Biology and Pharmacology, University of Texas Health Science Center at Houston , Houston, Texas
| | - Mykola Mamenko
- Department of Physiology, Medical College of Georgia, Augusta University , Augusta, Georgia
| | - Oleg Zaika
- Department of Integrative Biology and Pharmacology, University of Texas Health Science Center at Houston , Houston, Texas
| | - Charles S Wingo
- Division of Nephrology, Hypertension and Transplantation, Department of Medicine, University of Florida , Gainesville, Florida.,North Florida/South Georgia Veterans Health System, Gainesville, Florida
| | - Oleh Pochynyuk
- Department of Integrative Biology and Pharmacology, University of Texas Health Science Center at Houston , Houston, Texas
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14
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Toktanis G, Kaya-Sezginer E, Yilmaz-Oral D, Gur S. Potential therapeutic value of transient receptor potential channels in male urogenital system. Pflugers Arch 2018; 470:1583-1596. [PMID: 30194638 DOI: 10.1007/s00424-018-2188-y] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/16/2018] [Revised: 07/11/2018] [Accepted: 07/24/2018] [Indexed: 12/11/2022]
Abstract
Transient receptor potential (TRP) channels comprise a family of cation channels implicated in a variety of cellular processes including light, mechanical or chemical stimuli, temperature, pH, or osmolarity. TRP channel proteins are a diverse family of proteins that are expressed in many tissues. We debated our recent knowledge about the expression, function, and regulation of TRP channels in the different parts of the male urogenital system in health and disease. Emerging evidence suggests that dysfunction of TRP channels significantly contributes to the pathophysiology of urogenital diseases. So far, there are many efforts underway to determine if these channels can be used as drug targets to reverse declines in male urogenital function. Furthermore, developing safe and efficacious TRP channel modulators is warranted for male urogenital disorders in a clinical setting.
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Affiliation(s)
| | - Ecem Kaya-Sezginer
- Faculty of Pharmacy, Department of Biochemistry and Pharmacology, Ankara University, Tandogan, 06100, Ankara, Turkey
| | - Didem Yilmaz-Oral
- Faculty of Pharmacy, Department of Biochemistry and Pharmacology, Ankara University, Tandogan, 06100, Ankara, Turkey.,Faculty of Pharmacy, Department of Pharmacology, Cukurova University, Adana, Turkey
| | - Serap Gur
- Faculty of Pharmacy, Department of Biochemistry and Pharmacology, Ankara University, Tandogan, 06100, Ankara, Turkey.
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15
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Transient Receptor Potential Vanilloid 4 Channel Deficiency Aggravates Tubular Damage after Acute Renal Ischaemia Reperfusion. Sci Rep 2018; 8:4878. [PMID: 29559678 PMCID: PMC5861116 DOI: 10.1038/s41598-018-23165-0] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/29/2017] [Accepted: 03/05/2018] [Indexed: 12/31/2022] Open
Abstract
Transient receptor potential vanilloid 4 (TRPV4) cation channels are functional in all renal vascular segments and mediate endothelium-dependent vasorelaxation. Moreover, they are expressed in distinct parts of the tubular system and activated by cell swelling. Ischaemia/reperfusion injury (IRI) is characterized by tubular injury and endothelial dysfunction. Therefore, we hypothesised a putative organ protective role of TRPV4 in acute renal IRI. IRI was induced in TRPV4 deficient (Trpv4 KO) and wild-type (WT) control mice by clipping the left renal pedicle after right-sided nephrectomy. Serum creatinine level was higher in Trpv4 KO mice 6 and 24 hours after ischaemia compared to WT mice. Detailed histological analysis revealed that IRI caused aggravated renal tubular damage in Trpv4 KO mice, especially in the renal cortex. Immunohistological and functional assessment confirmed TRPV4 expression in proximal tubular cells. Furthermore, the tubular damage could be attributed to enhanced necrosis rather than apoptosis. Surprisingly, the percentage of infiltrating granulocytes and macrophages were comparable in IRI-damaged kidneys of Trpv4 KO and WT mice. The present results suggest a renoprotective role of TRPV4 during acute renal IRI. Further studies using cell-specific TRPV4 deficient mice are needed to clarify cellular mechanisms of TRPV4 in IRI.
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16
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Corrigan MA, Johnson GP, Stavenschi E, Riffault M, Labour MN, Hoey DA. TRPV4-mediates oscillatory fluid shear mechanotransduction in mesenchymal stem cells in part via the primary cilium. Sci Rep 2018; 8:3824. [PMID: 29491434 PMCID: PMC5830574 DOI: 10.1038/s41598-018-22174-3] [Citation(s) in RCA: 66] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/04/2017] [Accepted: 02/19/2018] [Indexed: 01/22/2023] Open
Abstract
Skeletal homeostasis requires the continued replenishment of the bone forming osteoblast from a mesenchymal stem cell (MSC) population, a process that has been shown to be mechanically regulated. However, the mechanisms by which a biophysical stimulus can induce a change in biochemical signaling, mechanotransduction, is poorly understood. As a precursor to loading-induced bone formation, deciphering the molecular mechanisms of MSC osteogenesis is a critical step in developing novel anabolic therapies. Therefore, in this study we characterize the expression of the mechanosensitive calcium channel Transient Receptor Potential subfamily V member 4 (TRPV4) in MSCs and demonstrate that TRPV4 localizes to areas of high strain, specifically the primary cilium. We demonstrate that TRPV4 is required for MSC mechanotransduction, mediating oscillatory fluid shear induced calcium signaling and early osteogenic gene expression. Furthermore, we demonstrate that TRPV4 can be activated pharmacologically eliciting a response that mirrors that seen with mechanical stimulation. Lastly, we show that TRPV4 localization to the primary cilium is functionally significant, with MSCs with defective primary cilia exhibiting an inhibited osteogenic response to TRPV4 activation. Collectively, this data demonstrates a novel mechanism of stem cell mechanotransduction, which can be targeted therapeutically, and further highlights the critical role of the primary cilium in MSC biology.
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Affiliation(s)
- Michele A Corrigan
- Trinity Centre for Bioengineering, Trinity Biomedical Sciences Institute, Trinity College Dublin, Dublin, 2, Ireland
- Department of Mechanical and Manufacturing Engineering, School of Engineering, Trinity College Dublin, Dublin, 2, Ireland
- Department of Mechanical, Aeronautical and Biomedical Engineering, University of Limerick, Limerick, Ireland
| | - Gillian P Johnson
- Trinity Centre for Bioengineering, Trinity Biomedical Sciences Institute, Trinity College Dublin, Dublin, 2, Ireland
- Department of Mechanical and Manufacturing Engineering, School of Engineering, Trinity College Dublin, Dublin, 2, Ireland
- Department of Mechanical, Aeronautical and Biomedical Engineering, University of Limerick, Limerick, Ireland
| | - Elena Stavenschi
- Trinity Centre for Bioengineering, Trinity Biomedical Sciences Institute, Trinity College Dublin, Dublin, 2, Ireland
- Department of Mechanical and Manufacturing Engineering, School of Engineering, Trinity College Dublin, Dublin, 2, Ireland
- Department of Mechanical, Aeronautical and Biomedical Engineering, University of Limerick, Limerick, Ireland
| | - Mathieu Riffault
- Trinity Centre for Bioengineering, Trinity Biomedical Sciences Institute, Trinity College Dublin, Dublin, 2, Ireland
- Department of Mechanical and Manufacturing Engineering, School of Engineering, Trinity College Dublin, Dublin, 2, Ireland
- Advanced Materials and Bioengineering Research Centre, Trinity College Dublin & RCSI, Dublin, 2, Ireland
| | - Marie-Noelle Labour
- Trinity Centre for Bioengineering, Trinity Biomedical Sciences Institute, Trinity College Dublin, Dublin, 2, Ireland
- Department of Mechanical and Manufacturing Engineering, School of Engineering, Trinity College Dublin, Dublin, 2, Ireland
- Department of Mechanical, Aeronautical and Biomedical Engineering, University of Limerick, Limerick, Ireland
| | - David A Hoey
- Trinity Centre for Bioengineering, Trinity Biomedical Sciences Institute, Trinity College Dublin, Dublin, 2, Ireland.
- Department of Mechanical and Manufacturing Engineering, School of Engineering, Trinity College Dublin, Dublin, 2, Ireland.
- Department of Mechanical, Aeronautical and Biomedical Engineering, University of Limerick, Limerick, Ireland.
- Advanced Materials and Bioengineering Research Centre, Trinity College Dublin & RCSI, Dublin, 2, Ireland.
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17
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Nag S, Resnick A. Biophysics and biofluid dynamics of primary cilia: evidence for and against the flow-sensing function. Am J Physiol Renal Physiol 2017. [DOI: 10.1152/ajprenal.00172.2017] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023] Open
Abstract
Primary cilia have been called “the forgotten organelle” for over 20 yr. As cilia now have their own journal and several books devoted to their study, perhaps it is time to reconsider the moniker “forgotten organelle.” In fact, during the drafting of this review, 12 relevant publications have been issued; we therefore apologize in advance for any relevant work we inadvertently omitted. What purpose is yet another ciliary review? The primary goal of this review is to specifically examine the evidence for and against the hypothesized flow-sensing function of primary cilia expressed by differentiated epithelia within a kidney tubule, bringing together differing disciplines and their respective conceptual and experimental approaches. We will show that understanding the biophysics/biomechanics of primary cilia provides essential information for understanding any potential role of ciliary function in disease. We will summarize experimental and mathematical models used to characterize renal fluid flow and incident force on primary cilia and to characterize the mechanical response of cilia to an externally applied force and discuss possible ciliary-mediated cell signaling pathways triggered by flow. Throughout, we stress the importance of separating the effects of fluid shear and stretch from the action of hydrodynamic drag.
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Affiliation(s)
- Subhra Nag
- Department of Biology, Geology, and Environmental Sciences, Cleveland State University, Cleveland, Ohio
| | - Andrew Resnick
- Department of Biology, Geology, and Environmental Sciences, Cleveland State University, Cleveland, Ohio
- Department of Physics, Cleveland State University, Cleveland, Ohio; and
- Center for Gene Regulation in Health and Disease, Cleveland State University, Cleveland, Ohio
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18
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Metatropic dysplasia in third trimester of pregnancy and a novel causative variant in the TRPV4 gene. Eur J Med Genet 2017; 60:365-368. [DOI: 10.1016/j.ejmg.2017.04.007] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/09/2016] [Revised: 04/06/2017] [Accepted: 04/10/2017] [Indexed: 12/22/2022]
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19
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Siroky BJ, Kleene NK, Kleene SJ, Varnell CD, Comer RG, Liu J, Lu L, Pachciarz NW, Bissler JJ, Dixon BP. Primary cilia regulate the osmotic stress response of renal epithelial cells through TRPM3. Am J Physiol Renal Physiol 2017; 312:F791-F805. [PMID: 28122715 PMCID: PMC5407065 DOI: 10.1152/ajprenal.00465.2015] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/15/2015] [Revised: 01/10/2017] [Accepted: 01/18/2017] [Indexed: 12/26/2022] Open
Abstract
Primary cilia sense environmental conditions, including osmolality, but whether cilia participate in the osmotic response in renal epithelial cells is not known. The transient receptor potential (TRP) channels TRPV4 and TRPM3 are osmoresponsive. TRPV4 localizes to cilia in certain cell types, while renal subcellular localization of TRPM3 is not known. We hypothesized that primary cilia are required for maximal activation of the osmotic response of renal epithelial cells and that ciliary TRPM3 and TRPV4 mediate that response. Ciliated [murine epithelial cells from the renal inner medullary collecting duct (mIMCD-3) and 176-5] and nonciliated (176-5Δ) renal cells expressed Trpv4 and Trpm3 Ciliary expression of TRPM3 was observed in mIMCD-3 and 176-5 cells and in wild-type mouse kidney tissue. TRPV4 was identified in cilia and apical membrane of mIMCD-3 cells by electrophysiology and in the cell body by immunofluorescence. Hyperosmolal stress at 500 mOsm/kg (via NaCl addition) induced the osmotic response genes betaine/GABA transporter (Bgt1) and aldose reductase (Akr1b3) in all ciliated cell lines. This induction was attenuated in nonciliated cells. A TRPV4 agonist abrogated Bgt1 and Akr1b3 induction in ciliated and nonciliated cells. A TRPM3 agonist attenuated Bgt1 and Akr1b3 induction in ciliated cells only. TRPM3 knockout attenuated Akr1b3 induction. Viability under osmotic stress was greater in ciliated than nonciliated cells. Akr1b3 induction was also less in nonciliated than ciliated cells when mannitol was used to induce hyperosmolal stress. These findings suggest that primary cilia are required for the maximal osmotic response in renal epithelial cells and that TRPM3 is involved in this mechanism. TRPV4 appears to modulate the osmotic response independent of cilia.
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Affiliation(s)
- Brian J Siroky
- Division of Nephrology and Hypertension, Cincinnati Children's Hospital Medical Center, Cincinnati, Ohio
| | - Nancy K Kleene
- Department of Molecular and Cellular Physiology, University of Cincinnati, Cincinnati, Ohio; and
| | - Steven J Kleene
- Department of Molecular and Cellular Physiology, University of Cincinnati, Cincinnati, Ohio; and
| | - Charles D Varnell
- Division of Nephrology and Hypertension, Cincinnati Children's Hospital Medical Center, Cincinnati, Ohio
| | - Raven G Comer
- Division of Nephrology and Hypertension, Cincinnati Children's Hospital Medical Center, Cincinnati, Ohio
| | - Jialiu Liu
- Division of Nephrology and Hypertension, Cincinnati Children's Hospital Medical Center, Cincinnati, Ohio
| | - Lu Lu
- Division of Nephrology and Hypertension, Cincinnati Children's Hospital Medical Center, Cincinnati, Ohio
| | - Nolan W Pachciarz
- Division of Nephrology and Hypertension, Cincinnati Children's Hospital Medical Center, Cincinnati, Ohio
| | - John J Bissler
- St. Jude Children's Research Hospital and Le Bonheur Children's Hospital, University of Tennessee Health Science Center, Memphis, Tennessee
| | - Bradley P Dixon
- Division of Nephrology and Hypertension, Cincinnati Children's Hospital Medical Center, Cincinnati, Ohio;
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20
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Mohammed SG, Arjona FJ, Latta F, Bindels RJM, Roepman R, Hoenderop JGJ. Fluid shear stress increases transepithelial transport of Ca
2+
in ciliated distal convoluted and connecting tubule cells. FASEB J 2017; 31:1796-1806. [DOI: 10.1096/fj.201600687rrr] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/17/2016] [Accepted: 01/03/2017] [Indexed: 11/11/2022]
Affiliation(s)
- Sami G. Mohammed
- Department of PhysiologyRadboud Institute for Molecular Life SciencesRadboud University Medical CenterNijmegenThe Netherlands
| | - Francisco J. Arjona
- Department of PhysiologyRadboud Institute for Molecular Life SciencesRadboud University Medical CenterNijmegenThe Netherlands
| | - Femke Latta
- Department of PhysiologyRadboud Institute for Molecular Life SciencesRadboud University Medical CenterNijmegenThe Netherlands
| | - René J. M. Bindels
- Department of PhysiologyRadboud Institute for Molecular Life SciencesRadboud University Medical CenterNijmegenThe Netherlands
| | - Ronald Roepman
- Department of Human GeneticsRadboud Institute for Molecular Life SciencesRadboud University Medical CenterNijmegenThe Netherlands
| | - Joost G. J. Hoenderop
- Department of PhysiologyRadboud Institute for Molecular Life SciencesRadboud University Medical CenterNijmegenThe Netherlands
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21
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TRPV4 is associated with central rather than nephrogenic osmoregulation. Pflugers Arch 2016; 468:1595-607. [PMID: 27364478 DOI: 10.1007/s00424-016-1850-5] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/21/2016] [Revised: 06/07/2016] [Accepted: 06/09/2016] [Indexed: 12/28/2022]
Abstract
TRPV4 is a polymodal cation channel expressed in osmosensitive neurons of the hypothalamus and in the mammalian nephron. The segmental distribution and role(s) of TRPV4 in osmoregulation remain debated. We investigated the renal distribution pattern of TRPV4 and the functional consequences of its disruption in mouse models. Using qPCR on microdissected segments, immunohistochemistry, and a LacZ reporter mouse, we found that TRPV4 is abundantly expressed in the proximal tubule, the late distal convoluted tubule, and throughout the connecting tubule and collecting duct, including principal and intercalated cells. TRPV4 was undetectable in the glomeruli and thick ascending limb and weakly abundant in the early distal convoluted tubule. Metabolic studies in Trpv4 (+/+) and Trpv4 (-/-) littermates revealed that the lack of TRPV4 did not influence activity, food and water intake, renal function, and urinary concentration at baseline. The mice showed a similar response to furosemide, water loading and deprivation, acid loading, and dietary NaCl restriction. However, Trpv4 (-/-) mice showed a significantly lower vasopressin synthesis and release after water deprivation, with a loss of the positive correlation between plasma osmolality and plasma vasopressin levels, and a delayed water intake upon acute administration of hypertonic saline. Specific activation of TRPV4 in primary cultures of proximal tubule cells increased albumin uptake, whereas no effect of TRPV4 deletion could be observed at baseline. These data reveal that, despite its abundant expression in tubular segments, TRPV4 does not play a major role in the kidney or is efficiently compensated when deleted. Instead, TRPV4 is critical for the release of vasopressin, the sensation of thirst, and the central osmoregulation.
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22
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Abstract
PURPOSE OF REVIEW The proximal tubule plays a critical role in the reabsorption of ions, solutes and low molecular weight proteins from the glomerular filtrate. Although the proximal tubule has long been known to acutely modulate ion reabsorption in response to changes in flow rates of the glomerular filtrate, it has only recently been discovered that proximal tubule cells can similarly adjust endocytic capacity in response to flow. This review synthesizes our current understanding of mechanosensitive regulation of endocytic capacity in proximal tubule epithelia and highlights areas of opportunity for future investigations. RECENT FINDINGS Recent studies have reported that the endocytic capacity of proximal tubule cells is dramatically increased upon exposure to flow and the accompanying fluid shear stress. Modulation of this pathway is dependent on increases in intracellular calcium initiated by bending of the primary cilium, and also requires purinergic receptor activation that is mediated by release of extracellular ATP. This article summarizes what is currently known about the signaling cascade that transduces changes in flow into alterations in endocytosis. We discuss the implications of this newly described regulatory pathway with respect to our understanding of protein retrieval by the kidney under normal conditions, and in diseases that present with low molecular weight proteinuria. SUMMARY Primary cilia act as mechanotransducers that modulate apical endocytic capacity in proximal tubule cells in response to changes in fluid shear stress.
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23
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Baratchi S, Almazi JG, Darby W, Tovar-Lopez FJ, Mitchell A, McIntyre P. Shear stress mediates exocytosis of functional TRPV4 channels in endothelial cells. Cell Mol Life Sci 2016; 73:649-66. [PMID: 26289129 PMCID: PMC11108432 DOI: 10.1007/s00018-015-2018-8] [Citation(s) in RCA: 57] [Impact Index Per Article: 7.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/09/2015] [Revised: 07/25/2015] [Accepted: 08/06/2015] [Indexed: 02/07/2023]
Abstract
Mechanosensitive ion channels are implicated in the biology of touch, pain, hearing and vascular reactivity; however, the identity of these ion channels and the molecular basis of their activation is poorly understood. We previously found that transient receptor potential vanilloid 4 (TRPV4) is a receptor operated ion channel that is sensitised and activated by mechanical stress. Here, we investigated the effects of mechanical stimulation on TRPV4 localisation and activation in native and recombinant TRPV4-expressing cells. We used a combination of total internal reflection fluorescence microscopy, cell surface biotinylation assay and Ca(2+) imaging with laser scanning confocal microscope to show that TRPV4 is expressed in primary vascular endothelial cells and that shear stress sensitises the response of TRPV4 to its agonist, GSK1016790A. The sensitisation was attributed to the recruitment of intracellular pools of TRPV4 to the plasma membrane, through the clathrin and dynamin-mediated exocytosis. The translocation was dependent on ILK/Akt signalling pathway, release of Ca(2+) from intracellular stores and we demonstrated that shear stress stimulated phosphorylation of TRPV4 at tyrosine Y110. Our findings implicate calcium-sensitive TRPV4 translocation in the regulation of endothelial responses to mechanical stimulation.
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Affiliation(s)
- Sara Baratchi
- School of Medical Sciences and Health Innovations Research Institute, RMIT University, Melbourne, VIC, 3083, Australia
| | - Juhura G Almazi
- School of Medical Sciences and Health Innovations Research Institute, RMIT University, Melbourne, VIC, 3083, Australia
| | - William Darby
- School of Medical Sciences and Health Innovations Research Institute, RMIT University, Melbourne, VIC, 3083, Australia
| | - Francisco J Tovar-Lopez
- School of Electrical and Computer Engineering, RMIT University, Melbourne, VIC, 3001, Australia
| | - Arnan Mitchell
- School of Electrical and Computer Engineering, RMIT University, Melbourne, VIC, 3001, Australia
| | - Peter McIntyre
- School of Medical Sciences and Health Innovations Research Institute, RMIT University, Melbourne, VIC, 3083, Australia.
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24
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Bhaskar LVKS, Elumalai R, Periasamy S. Pathways, perspectives and pursuits in polycystic kidney disease. J Nephropharmacol 2015; 5:41-48. [PMID: 28197498 PMCID: PMC5297506] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/01/2015] [Accepted: 11/25/2015] [Indexed: 11/01/2022] Open
Abstract
Polycystic kidney disease (PKD) is characterized by the growth of numerous cysts in the kidneys. When cysts form in the kidneys, they are filled with fluid. PKD cysts can profoundly enlarge the kidneys while replacing much of the normal structure, resulting in reduced kidney function and leading to kidney failure. Autosomal dominant polycystic kidney disease (ADPKD) is a hereditary disease that occurs in one out of 1000 humans. PKD and its causes are being dissected through studies of human populations and through the use of animal models. Mouse models in particular have made a substantial contribution to our understanding of the gene pathways involved in the pathogenesis and the nature of signaling molecules that act in a tissue-specific manner at critical stages of cyst development. PKD has a number of characteristics that make it uniquely challenging for the development of therapies to slowdown disease progression. This review provides current understanding of the etiopathology, pathways involved and therapeutic targets of PKDs.
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Affiliation(s)
- L. V. K. S. Bhaskar
- 1Sickle Cell Institute Chhattisgarh, Raipur, India
,Corresponding author: Dr. L.V. K. S. Bhaskar,
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25
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Mamenko M, Zaika O, Boukelmoune N, O'Neil RG, Pochynyuk O. Deciphering physiological role of the mechanosensitive TRPV4 channel in the distal nephron. Am J Physiol Renal Physiol 2015; 308:F275-86. [PMID: 25503733 PMCID: PMC4329491 DOI: 10.1152/ajprenal.00485.2014] [Citation(s) in RCA: 36] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/28/2014] [Accepted: 12/08/2014] [Indexed: 12/14/2022] Open
Abstract
Long-standing experimental evidence suggests that epithelial cells in the renal tubule are able to sense osmotic and pressure gradients caused by alterations in ultrafiltrate flow by elevating intracellular Ca(2+) concentration. These responses are viewed as critical regulators of a variety of processes ranging from transport of water and solutes to cellular growth and differentiation. A loss in the ability to sense mechanical stimuli has been implicated in numerous pathologies associated with systemic imbalance of electrolytes and to the development of polycystic kidney disease. The molecular mechanisms conferring mechanosensitive properties to epithelial tubular cells involve activation of transient receptor potential (TRP) channels, such as TRPV4, allowing direct Ca(2+) influx to increase intracellular Ca(2+) concentration. In this review, we critically analyze the current evidence about signaling determinants of TRPV4 activation by luminal flow in the distal nephron and discuss how dysfunction of this mechanism contributes to the progression of polycystic kidney disease. We also review the physiological relevance of TRPV4-based mechanosensitivity in controlling flow-dependent K(+) secretion in the distal renal tubule.
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Affiliation(s)
- M Mamenko
- Department of Integrative Biology and Pharmacology, University of Texas Health Science Center, Houston, Texas
| | - O Zaika
- Department of Integrative Biology and Pharmacology, University of Texas Health Science Center, Houston, Texas
| | - N Boukelmoune
- Department of Integrative Biology and Pharmacology, University of Texas Health Science Center, Houston, Texas
| | - R G O'Neil
- Department of Integrative Biology and Pharmacology, University of Texas Health Science Center, Houston, Texas
| | - O Pochynyuk
- Department of Integrative Biology and Pharmacology, University of Texas Health Science Center, Houston, Texas
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26
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Leddy HA, McNulty AL, Guilak F, Liedtke W. Unraveling the mechanism by which TRPV4 mutations cause skeletal dysplasias. Rare Dis 2014; 2:e962971. [PMID: 26942100 PMCID: PMC4755236 DOI: 10.4161/2167549x.2014.962971] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/05/2014] [Accepted: 09/03/2014] [Indexed: 01/02/2023] Open
Abstract
Transient Receptor Potential Vanilloid 4 (TRPV4) is a mechano- and osmosensitive cation channel that is highly expressed in chondrocytes, the cells in cartilage. A large number of mutations in TRPV4 have been linked to skeletal dysplasias, and the goal of this addendum is to shed light on the mechanisms by which mutations in TRPV4 can cause skeletal dysplasias by focusing on 3 recent publications. These papers suggest that skeletal dysplasia-causing TRPV4 mutations reprogram chondrocytes to increase follistatin production, which inhibits BMP signaling, thus slowing the process of endochondral ossification and leading to skeletal dysplasia. In spite of these important advances in our understanding of the disease mechanism, much remains to be elucidated. Nonetheless, these new data suggest that inhibiting aberrant TRPV4 activity in the cartilage may be a promising direction for therapeutic intervention.
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Affiliation(s)
- Holly A Leddy
- Department of orthopedic Surgery; Duke University Medical Center ; Durham, NC USA
| | - Amy L McNulty
- Department of orthopedic Surgery; Duke University Medical Center ; Durham, NC USA
| | - Farshid Guilak
- Department of orthopedic Surgery; Duke University Medical Center ; Durham, NC USA
| | - Wolfgang Liedtke
- Department of Neurology and Duke University Clinics for Pain and Palliative Care; Duke University Medical Center ; Durham, NC USA
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27
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Goldenberg NM, Ravindran K, Kuebler WM. TRPV4: physiological role and therapeutic potential in respiratory diseases. Naunyn Schmiedebergs Arch Pharmacol 2014; 388:421-36. [PMID: 25342095 DOI: 10.1007/s00210-014-1058-1] [Citation(s) in RCA: 56] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/02/2014] [Accepted: 10/10/2014] [Indexed: 01/11/2023]
Abstract
Members of the family of transient receptor potential (TRP) channels have been implicated in the pathophysiology of a host of lung diseases. The role of these multimodal cation channels in lung homeostasis is thought to stem from their ability to respond to changes in mechanical stimuli (i.e., shear and stretch), as well as to various protein and lipid mediators. The vanilloid subfamily member, TRPV4, which is highly expressed in the majority of lung cell types, is well positioned for critical involvement in several pulmonary conditions, including edema formation, control of pulmonary vascular tone, and the lung response to local or systemic inflammatory insults. In recent years, several pharmacological inhibitors of TRPV4 have been developed, and the current generation of compounds possess high affinity and specificity for TRPV4. As such, we have now entered a time where the therapeutic potential of TRPV4 inhibitors can be systematically examined in a variety of lung diseases. Due to this fact, this review seeks to describe the current state of the art with respect to the role of TRPV4 in pulmonary homeostasis and disease, and to highlight the current and future roles of TRPV4 inhibitors in disease treatment. We will first focus on genera aspects of TRPV4 structure and function, and then will discuss known roles for TRPV4 in pulmonary diseases, including pulmonary edema formation, pulmonary hypertension, and acute lung injury. Finally, both promising aspects and potential pitfalls of the clinical use of TRPV4 inhibitors will be examined.
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Affiliation(s)
- Neil M Goldenberg
- Department of Anesthesia, University of Toronto, Toronto, ON, Canada
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Saxena A, Bachelor M, Park YH, Carreno FR, Nedungadi TP, Cunningham JT. Angiotensin II induces membrane trafficking of natively expressed transient receptor potential vanilloid type 4 channels in hypothalamic 4B cells. Am J Physiol Regul Integr Comp Physiol 2014; 307:R945-55. [PMID: 25080500 DOI: 10.1152/ajpregu.00224.2014] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/18/2023]
Abstract
Transient receptor potential vanilloid family type 4 (TRPV4) channels are expressed in central neuroendocrine neurons and have been shown to be polymodal in other systems. We previously reported that in the rodent, a model of dilutional hyponatremia associated with hepatic cirrhosis, TRPV4 expression is increased in lipid rafts from the hypothalamus and that this effect may be angiotensin dependent. In this study, we utilized the immortalized neuroendocrine rat hypothalamic 4B cell line to more directly test the effects of angiotensin II (ANG II) on TRPV4 expression and function. Our results demonstrate the expression of corticotropin-releasing factor (CRF) transcripts, for sex-determining region Y (SRY) (male genotype), arginine vasopressin (AVP), TRPV4, and ANG II type 1a and 1b receptor in 4B cells. After a 1-h incubation in ANG II (100 nM), 4B cells showed increased TRPV4 abundance in the plasma membrane fraction, and this effect was prevented by the ANG II type 1 receptor antagonist losartan (1 μM) and by a Src kinase inhibitor PP2 (10 μM). Ratiometric calcium imaging experiments demonstrated that ANG II incubation potentiated TRPV4 agonist (GSK 1016790A, 20 nM)-induced calcium influx (control 18.4 ± 2.8% n = 5 and ANG II 80.5 ± 2.4% n = 5). This ANG II-induced increase in calcium influx was also blocked by 1 μM losartan and 10 μM PP2 (losartan 26.4 ± 3.8% n = 5 and PP2 19.7 ± 3.9% n = 5). Our data suggests that ANG II can increase TRPV4 channel membrane expression in 4B cells through its action on AT1R involving a Src kinase pathway.
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Affiliation(s)
- Ashwini Saxena
- Department of Integrative Physiology and Anatomy and Cardiovascular Research Institute, University of North Texas Health Science Center at Fort Worth, Fort Worth, Texas
| | - Martha Bachelor
- Department of Integrative Physiology and Anatomy and Cardiovascular Research Institute, University of North Texas Health Science Center at Fort Worth, Fort Worth, Texas
| | - Yong H Park
- Department of Pharmacology and Neuroscience & North Texas Eye Research Institute, University of North Texas Health Science Center at Fort Worth, Fort Worth, Texas; and
| | - Flavia R Carreno
- Department of Pharmacology & Center for Biomedical Neuroscience, University of Texas Health Science Center at San Antonio, San Antonio, Texas
| | - T Prashant Nedungadi
- Department of Integrative Physiology and Anatomy and Cardiovascular Research Institute, University of North Texas Health Science Center at Fort Worth, Fort Worth, Texas
| | - J Thomas Cunningham
- Department of Integrative Physiology and Anatomy and Cardiovascular Research Institute, University of North Texas Health Science Center at Fort Worth, Fort Worth, Texas;
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Abstract
Mechanosensitive channels allow cells to respond to changes in membrane stretch that occur due to external stimuli like pressure or flow or that occur because of osmotically induced cell swelling or shrinkage. Ion fluxes through the channels change the membrane potential and ion concentrations and link the stretch to cellular signalling. Changes in cellular activity evoked by mechanical stimuli can be used to elicit local tissue responses or can be transmitted further to generate more widespread responses. Channels can respond directly to membrane stress, can be conferred mechanosensitive by interaction with structural proteins, or can be activated by mechanosensitive signalling pathways. Because mechanosensitive channels are often nonselective cation channels, and invertebrate TRP isoforms are involved in mechanosensation, many of the mammalian TRP isoforms have been investigated with regard to their mechanosensitivity. There is evidence that members of the TRPC, TRPV, TRPM, TRPA and TRPP subfamilies could be in some way mechanosensitive, and each of the activation mechanisms described above is used by a TRP channel. TRP channels may be involved in mechanosensitive processes ranging from flow and pressure sensing in the vasculature and other organs to mechanosensation in sensory neurones and sensory organs. There is also evidence for a role of mechano- or osmosensitive TRP isoforms in osmosensing and the regulation of cell volume. Often, a number of different TRP isoforms have been implicated in a single type of mechanosensitive response. In many cases, the involvement of the isoforms needs to be confirmed, and their exact role in the signalling process determined.
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Affiliation(s)
- Tim D Plant
- Pharmakologisches Institut, BPC-Marburg, FB-Medizin, Philipps-Universität Marburg, Karl-von-Frisch-Straße 1, 35032, Marburg, Germany,
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Klausen TK, Janssens A, Prenen J, Owsianik G, Hoffmann EK, Pedersen SF, Nilius B. Single point mutations of aromatic residues in transmembrane helices 5 and -6 differentially affect TRPV4 activation by 4α-PDD and hypotonicity: implications for the role of the pore region in regulating TRPV4 activity. Cell Calcium 2013; 55:38-47. [PMID: 24342753 DOI: 10.1016/j.ceca.2013.11.001] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/06/2013] [Accepted: 11/08/2013] [Indexed: 12/20/2022]
Abstract
The importance of the TRPV4 channel for human physiology has been highlighted in recent years with the identification of an increasing number of hereditary diseases associated with mutations of this channel. However, the functional understanding of TRPV4 associated pathologies remains a puzzle due to incomplete understanding of the polymodal regulation of TRPV4 channels and lack of insight into the structure-function relationship of the channel. In this work, we identified a series of highly conserved aromatic residues in transmembrane (TM) helices 5-6 with profound importance for TRPV4 activity. Substituting F617, Y621 or F624 in TM5 with leucine reduced channel sensitivity to the agonist 4α-PDD and heat, yet two of these mutants - F617L and Y621L - showed increased activation in response to cell swelling. In TM6, a Y702L mutation significantly reduced sensitivity to all of the above stimuli. In conclusion, we have identified residues in TM5-6 which differentially affect heat and agonist activation, and we have demonstrated distinct activation pathways for 4α-PDD and osmolarity.
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Affiliation(s)
- Thomas Kjær Klausen
- KU Leuven, Department of Cellular and Molecular Medicine, Laboratory Ion Channel Research, Campus Gasthuisberg, Herestraat 49, Bus 802, Leuven, Belgium; Department of Biology, The August Krogh Building, Universitetsparken 13, DK-2100 Copenhagen Ø, Denmark.
| | - Annelies Janssens
- KU Leuven, Department of Cellular and Molecular Medicine, Laboratory Ion Channel Research, Campus Gasthuisberg, Herestraat 49, Bus 802, Leuven, Belgium
| | - Jean Prenen
- KU Leuven, Department of Cellular and Molecular Medicine, Laboratory Ion Channel Research, Campus Gasthuisberg, Herestraat 49, Bus 802, Leuven, Belgium
| | - Grzegorz Owsianik
- KU Leuven, Department of Cellular and Molecular Medicine, Laboratory Ion Channel Research, Campus Gasthuisberg, Herestraat 49, Bus 802, Leuven, Belgium
| | - Else Kay Hoffmann
- Department of Biology, The August Krogh Building, Universitetsparken 13, DK-2100 Copenhagen Ø, Denmark
| | - Stine Falsig Pedersen
- Department of Biology, The August Krogh Building, Universitetsparken 13, DK-2100 Copenhagen Ø, Denmark
| | - Bernd Nilius
- KU Leuven, Department of Cellular and Molecular Medicine, Laboratory Ion Channel Research, Campus Gasthuisberg, Herestraat 49, Bus 802, Leuven, Belgium
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Sasaki S, Yui N, Noda Y. Actin directly interacts with different membrane channel proteins and influences channel activities: AQP2 as a model. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2013; 1838:514-20. [PMID: 23770358 DOI: 10.1016/j.bbamem.2013.06.004] [Citation(s) in RCA: 50] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/01/2013] [Revised: 06/01/2013] [Accepted: 06/06/2013] [Indexed: 11/26/2022]
Abstract
The interplay between actin and 10 membrane channel proteins that have been shown to directly bind to actin are reviewed. The 10 membrane channel proteins covered in this review are aquaporin 2 (AQP2), cystic fibrosis transmembrane conductance regulator (CFTR), ClC2, short form of ClC3 (sClC3), chloride intracellular channel 1 (CLIC1), chloride intracellular channel 5 (CLIC5), epithelial sodium channel (ENaC), large-conductance calcium-activated potassium channel (Maxi-K), transient receptor potential vanilloid 4 (TRPV4), and voltage-dependent anion channel (VDAC), with particular attention to AQP2. In regard to AQP2, most reciprocal interactions between actin and AQP2 occur during intracellular trafficking, which are largely mediated through indirect binding. Actin and the actin cytoskeleton work as cables, barriers, stabilizers, and force generators for motility. However, as with ENaC, the effects of actin cytoskeleton on channel gating should be investigated further. This article is part of a Special Issue entitled: Reciprocal influences between cell cytoskeleton and membrane channels, receptors and transporters. Guest Editor: Jean Claude Hervé.
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Affiliation(s)
- Sei Sasaki
- Department of Nephrology, Graduate School of Medical and Dental Sciences, Tokyo Medical and Dental University, Tokyo 113-8519, Japan.
| | - Naofumi Yui
- Department of Nephrology, Graduate School of Medical and Dental Sciences, Tokyo Medical and Dental University, Tokyo 113-8519, Japan
| | - Yumi Noda
- Department of Nephrology, Graduate School of Medical and Dental Sciences, Tokyo Medical and Dental University, Tokyo 113-8519, Japan
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Mamenko M, Zaika OL, Boukelmoune N, Berrout J, O'Neil RG, Pochynyuk O. Discrete control of TRPV4 channel function in the distal nephron by protein kinases A and C. J Biol Chem 2013; 288:20306-14. [PMID: 23709216 DOI: 10.1074/jbc.m113.466797] [Citation(s) in RCA: 34] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023] Open
Abstract
We have recently documented that the Ca(2+)-permeable TRPV4 channel, which is abundantly expressed in distal nephron cells, mediates cellular Ca(2+) responses to elevated luminal flow. In this study, we combined Fura-2-based [Ca(2+)]i imaging with immunofluorescence microscopy in isolated split-opened distal nephrons of C57BL/6 mice to probe the molecular determinants of TRPV4 activity and subcellular distribution. We found that activation of the PKC pathway with phorbol 12-myristate 13-acetate significantly increased [Ca(2+)]i responses to flow without affecting the subcellular distribution of TRPV4. Inhibition of PKC with bisindolylmaleimide I diminished cellular responses to elevated flow. In contrast, activation of the PKA pathway with forskolin did not affect TRPV4-mediated [Ca(2+)]i responses to flow but markedly shifted the subcellular distribution of the channel toward the apical membrane. These actions were blocked with the specific PKA inhibitor H-89. Concomitant activation of the PKA and PKC cascades additively enhanced the amplitude of flow-induced [Ca(2+)]i responses and greatly increased basal [Ca(2+)]i levels, indicating constitutive TRPV4 activation. This effect was precluded by the selective TRPV4 antagonist HC-067047. Therefore, the functional status of the TRPV4 channel in the distal nephron is regulated by two distinct signaling pathways. Although the PKA-dependent cascade promotes TRPV4 trafficking and translocation to the apical membrane, the PKC-dependent pathway increases the activity of the channel on the plasma membrane.
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Affiliation(s)
- Mykola Mamenko
- Department of Integrative Biology and Pharmacology, The University of Texas Health Science Center at Houston, Houston, Texas 77030, USA
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