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  • The polymodal ion channel TRPV4 modulates calcium flux, spiking rate, and apoptosis of mouse retinal ganglion cells
    Ryskamp, Daniel A. ...
    Sustained increase in intraocular pressure represents a major risk factor for eye disease, yet the cellular mechanisms of pressure transduction in the posterior eye are essentially unknown. Here we ... show that the mouse retina expresses mRNA and protein for the polymodal transient receptor potential vanilloid 4 (TRPV4) cation channel known to mediate osmotransduction and mechanotransduction. TRPV4 antibodies labeled perikarya, axons, and dendrites of retinal ganglion cells (RGCs) and intensely immunostained the optic nerve head. Muller glial cells, but not retinal astrocytes or microglia, also expressed TRPV4 immunoreactivity. The selective TRPV4 agonists 4alpha-PDD and GSK1016790A elevated šCa2+đi in dissociated RGCs in a dose-dependent manner, whereas the TRPV1 agonist capsaicin had no effect on šCa2+đ(RGC). Exposure tohypotonic stimulation evoked robust increases in šCa2+đ(RGC). RGC responses to TRPV4-selective agonists and hypotonic stimulation were absent in Ca2+ -free saline and were antagonized by the nonselective TRP channel antagonists Ruthenium Red and gadolinium, but were unaffected by the TRPV1 antagonist capsazepine. TRPV4-selective agonists increased the spiking frequency recordedfrom intact retinas recorded with multielectrode arrays. Sustained exposure to TRPV4 agonists evoked dose-dependent apoptosis of RGCs. Our results demonstrate functional TRPV4 expression in RGCs and suggest that its activation mediates response to membrane stretch leading to elevated šCa2+đi and augmented excitability. Excessive Ca2+ influx through TRPV4 predisposes RGCs to activation of Ca2+ -dependent proapoptotic signaling pathways, indicating that TRPV4 is a component of the response mechanism to pathologicalelevations of intraocular pressure.
    Source: The Journal of neuroscience. - ISSN 0270-6474 (Vol. 31, iss. 19, 2011, str. 7089-7101)
    Type of material - article, component part
    Publish date - 2011
    Language - english
    COBISS.SI-ID - 29590233
    DOI

source: The Journal of neuroscience. - ISSN 0270-6474 (Vol. 31, iss. 19, 2011, str. 7089-7101)
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