The polymodal ion channel transient receptor potential vanilloid 4 modulates calcium flux, spiking rate, and apoptosis of mouse retinal ganglion cells

Daniel A. Ryskamp, Paul Witkovsky, Peter Barabas, Wei Huang, Christopher Koehler, Nikolay P. Akimov, Suk Hee Lee, Shiwani Chauhan, Wei Xing, René C. Rentería, Wolfgang Liedtke, David Križaj

Research output: Contribution to journalArticlepeer-review

122 Scopus citations

Abstract

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. Müller glial cells, but not retinal astrocytes or microglia, also expressed TRPV4 immunoreactivity. The selective TRPV4 agonists 4α-PDD and GSK1016790A elevated [Ca2+]i in dissociated RGCs in a dose-dependent manner, whereas the TRPV1 agonist capsaicin had no effect on [Ca2+]RGC. Exposure to hypotonic stimulation evoked robust increases in [Ca2+]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 recorded from 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 tomembranestretch leading to elevated [Ca2+]i and augmented excitability. Excessive Ca2+ influx through TRPV4predisposes RGCs to activation of Ca2+-dependent proapoptotic signaling pathways, indicating thatTRPV4is a component of the response mechanism to pathological elevations of intraocular pressure.

Original languageEnglish (US)
Pages (from-to)7089-7101
Number of pages13
JournalJournal of Neuroscience
Volume31
Issue number19
DOIs
StatePublished - May 11 2011

ASJC Scopus subject areas

  • Neuroscience(all)

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