title: TRPV4 channels activity in bovine articular chondrocytes: regulation by obesity-associated mediators.
abstract: Turnover of the cartilage extracellular matrix depends exclusively on chondrocytes and varies in response to load and osmolarity fluctuations. Obesity can affect chondrocyte physiology; adipokines, insulin and proinflammatory cytokines levels are all altered in the obese and are related to matrix turnover impairments and thus to osteoarthritis. TRPV4, a mechanosensitive cation channel, is responsible for reacting to hypotonic variations. In this study, the presence and activity of TRPV4 channels in bovine chondrocytes were evaluated using the whole-cell patch-clamp technique and fluorescence measurements to perform characterisations of these channels and to determine intracellular calcium responses. The expression of TRPV4 was determined by RT-PCR. The TRPV4 regulation by hypotonic shock, insulin and adipokines were analysed. Hypoosmolarity induced a Gd(3+)-, ruthenium red-, and HC-067047-sensitive current, predominantly inward, an intracellular Ca(2+) concentration increase and a membrane depolarisation. The current had a reversal potential of +28±4mV and exhibited preferential permeability to Ca(2+); 4αPDD, a specific TRPV4 agonist, evoked the same response. TNFα, IL-1β, insulin, and, to a lesser degree, leptin and resistin attenuated the TRPV4-mediated effects; in contrast, adiponectin did not affect them. These results confirm the function of TRPV4 in bovine articular chondrocytes and its regulation by obesity-associated mediators.
authors.affiliation: Facultad Ciencias de la Salud Universidad Tecnológica de Pereira, Pereira, Colombia. Electronic address: jcsanchez@utp.edu.co.
authors.forename: Julio C
authors.initials: JC
authors.lastname: Sánchez
authors.affiliation: Facultad Ciencias de la Salud Universidad Tecnológica de Pereira, Pereira, Colombia.
authors.forename: Diego F
authors.initials: DF
authors.lastname: López-Zapata
authors.affiliation: Department of Physiology, Anatomy and Genetics University of Oxford, Oxford, UK.
authors.forename: Robert J
authors.initials: RJ
authors.lastname: Wilkins
mesh_terms: D000818:Animals; D002118:Calcium / Q000378:metabolism; D002358:Cartilage, Articular / Q000166:cytology / Q000187:drug effects / Q000378:metabolism*; D002417:Cattle; D002478:Cells, Cultured; D019902:Chondrocytes / Q000166:cytology / Q000187:drug effects / Q000378:metabolism*; D005682:Gadolinium / Q000494:pharmacology; D007328:Insulin / Q000378:metabolism / Q000494:pharmacology*; D053583:Interleukin-1beta / Q000378:metabolism / Q000494:pharmacology*; D020738:Leptin / Q000378:metabolism / Q000494:pharmacology; D009025:Morpholines / Q000494:pharmacology; D009765:Obesity / Q000378:metabolism; D009997:Osmotic Pressure / Q000187:drug effects; D018408:Patch-Clamp Techniques; D011758:Pyrroles / Q000494:pharmacology; D052243:Resistin / Q000378:metabolism / Q000494:pharmacology; D012430:Ruthenium Red / Q000494:pharmacology; D050916:TRPV Cation Channels / Q000187:drug effects* / Q000378:metabolism*; D014409:Tumor Necrosis Factor-alpha / Q000378:metabolism / Q000494:pharmacology*
chemical_list: C573308:HC-067047; D007328:Insulin; D053583:Interleukin-1beta; D020738:Leptin; D009025:Morpholines; D011758:Pyrroles; D052243:Resistin; D050916:TRPV Cation Channels; D014409:Tumor Necrosis Factor-alpha; D012430:Ruthenium Red; D005682:Gadolinium; D002118:Calcium
keywords: Calcium; Chondrocyte; Electrophysiology; Hypoosmolarity; TRPV4 channels