TRPV4 is functionally expressed in oligodendrocyte precursor cells and enhances their proliferation

[Speaker] Kana Ohashi:1
[Co-author] Ayane Deyashiki:1, Takahito Miyake:1, Kazuki Nagayasu:1, Koji Shibasaki:2, Hisashi Shirakawa:1, Shuji Kaneko:1
1:Department of Molecular Pharmacology, Graduate School of Pharmaceutical Sciences, Kyoto University, Japan, 2:Department of Molecular and Cellular Neurology, Graduate School of Medicine, Gunma University, Japan

Oligodendrocytes, which differentiate from oligodendrocyte precursor cells (OPCs), ensheath axons with myelin, play an essential role in rapid conduction of action potentials, and metabolically support neurons. Elucidation of the mechanisms underlying the proliferation, migration, differentiation, and survival of OPCs is considered indispensable for determining the causes of central nervous system diseases. However, the relationship between these functions of OPCs and their intracellular Ca2+ signaling has not been fully elucidated. Here, we investigated the function of transient receptor potential vanilloid 4 (TRPV4), a Ca2+-permeable channel that responds to hypo-osmolarity, mild temperature, mechanical stimulation, and endogenous arachidonic acid metabolites, in OPCs.

Fluorescence in situ hybridization and immunohistochemistry were performed in rat corpus callosum. Primary OPC cultures were prepared from cerebral cortices of 0-2-day-old Wistar/ST rats. Ca2+ imaging was conducted using Fura 2-AM. MTT assay and BrdU incorporation assay were performed 24 h after treatment of TRPV4 agonist GSK1016790A. Cell migration was evaluated by scratch-wound assay and differentiation was analyzed by RT-PCR, using PDGFRα as a OPC marker and MBP as a mature oligodendrocyte marker.

Trpv4 mRNA was detected in OPCs in vivo and in primary cultured rat OPCs. In Ca2+ imaging experiments and whole cell patch clamp recordings, treatment with the selective TRPV4 agonist GSK1016790A induced sustained elevation of the intracellular Ca2+ concentration in a concentration-dependent manner and a current response in OPCs, which were almost completely suppressed by co-treatment with the selective TRPV4 antagonist HC067047. Stimulation of TRPV4 by GSK1016790A augmented OPC proliferation, which was abolished by co-treatment with HC067047, the intracellular Ca2+ chelator BAPTA-AM, and the protein kinase C inhibitor bisindolylmaleimide II. By contrast, GSK1016790A did not significantly affect the migration or expression level of differentiation marker PDGFRα and MBP.

These results suggest that TRPV4 is functionally expressed in OPCs and enhances the proliferation of these cells without affecting their ability to differentiate into oligodendrocytes.

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