Thermosensitive TRPV4 channels mediate temperature-dependent microglia movement.
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ABSTRACT:
SUBMITTER: Nishimoto R
PROVIDER: S-EPMC8092382 | biostudies-literature |
REPOSITORIES: biostudies-literature
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Project description:TRPV4 is a non-selective cation channel that tunes the function of different tissues including the vascular endothelium, lung, chondrocytes, and neurons. GSK1016790A is the selective and potent agonist of TRPV4 and a pharmacological tool that is used to study the TRPV4 physiological function in vitro and in vivo. It remains unknown how the sensitivity of TRPV4 to this agonist is regulated. The spatial and temporal dynamics of receptors are the major determinants of cellular responses to stimuli. Membrane translocation has been shown to control the response of several members of the transient receptor potential (TRP) family of ion channels to different stimuli. Here, we show that TRPV4 stimulation with GSK1016790A caused an increase in [Ca2+]i that is stable for a few minutes. Single molecule analysis of TRPV4 channels showed that the density of TRPV4 at the plasma membrane is controlled through two modes of membrane trafficking, complete, and partial vesicular fusion. Further, we show that the density of TRPV4 at the plasma membrane decreased within 20 min, as they translocate to the recycling endosomes and that the surface density is dependent on the release of calcium from the intracellular stores and is controlled via a PI3K, PKC, and RhoA signaling pathway.
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Project description:BACKGROUND AND PURPOSE:Heat-sensitive transient receptor potential vanilloid (TRPV) channels are expressed in various epithelial tissues regulating, among else, barrier functions. Their expression is well established in the distal nephron; however, we have no data about their presence in podocytes. As podocytes are indispensable in the formation of the glomerular filtration barrier, we investigated the presence and function of Ca2+ -permeable TRPV1-4 channels in human podocyte cultures. EXPERIMENTAL APPROACH:Expression of TRPV1-4 channels was investigated at protein (immunocytochemistry, Western blot) and mRNA (Q-PCR) level in a conditionally immortalized human podocyte cell line. Channel function was assessed by measuring intracellular Ca2+ concentration using Flou-4 Ca2+ -indicator dye and patch clamp electrophysiology upon applying various activators and inhibitors. KEY RESULTS:Thermosensitive TRP channels were expressed in podocytes. The TRPV1-specific agonists capsaicin and resiniferatoxin did not affect the intracellular Ca2+ concentration. Cannabidiol, an activator of TRPV2 and TRPV4 channels, induced moderate Ca2+ -influxes, inhibited by both tranilast and HC067047, blockers of TRPV2 and TRPV4 channels respectively. The TRPV4-specific agonists GSK1016790A and 4?-phorbol 12,13-didecanoate induced robust Ca2+ -signals which were abolished by HC067047. Non-specific agonists of TRPV3 channels induced marked Ca2+ transients. However, TRPV3 channel blockers, ruthenium red and isopentenyl diphosphate only partly inhibited the responses and TRPV3 silencing was ineffective suggesting remarkable off-target effects of the compounds. CONCLUSION AND IMPLICATIONS:Our results indicate the functional presence of TRPV4 and other thermosensitive TRPV channels in human podocytes and raise the possibility of their involvement in the regulation of glomerular filtration barrier.
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