Referenced in: none

Automatically associated channels: TRP , TRPV , TRPV4

Title: An aquaporin-4/transient receptor potential vanilloid 4 (AQP4/TRPV4) complex is essential for cell-volume control in astrocytes.

Authors: Valentina Benfenati, Marco Caprini, Melania Dovizio, Maria N Mylonakou, Stefano Ferroni, Ole P Ottersen, Mahmood Amiry-Moghaddam

Journal, date & volume: Proc. Natl. Acad. Sci. U.S.A., 2011 Feb 8 , 108, 2563-8

PubMed link: http://www.ncbi.nlm.nih.gov/pubmed/21262839

Abstract
Regulatory volume decrease (RVD) is a key mechanism for volume control that serves to prevent detrimental swelling in response to hypo-osmotic stress. The molecular basis of RVD is not understood. Here we show that a complex containing aquaporin-4 (AQP4) and transient receptor potential vanilloid 4 (TRPV4) is essential for RVD in astrocytes. Astrocytes from AQP4-KO mice and astrocytes treated with TRPV4 siRNA fail to respond to hypotonic stress by increased intracellular Ca(2+) and RVD. Coimmunoprecipitation and immunohistochemistry analyses show that AQP4 and TRPV4 interact and colocalize. Functional analysis of an astrocyte-derived cell line expressing TRPV4 but not AQP4 shows that RVD and intracellular Ca(2+) response can be reconstituted by transfection with AQP4 but not with aquaporin-1. Our data indicate that astrocytes contain a TRPV4/AQP4 complex that constitutes a key element in the brain's volume homeostasis by acting as an osmosensor that couples osmotic stress to downstream signaling cascades.