Referenced in: none

Automatically associated channels: Cav1.3

Title: Rab27a GTPase modulates L-type Ca(2+) channel function via interaction with the II-III linker of CaV1.3 subunit.

Authors: Nadine Reichhart, Magdalena Markowski, Shimpei Ishiyama, Andrea Wagner, Sergio Crespo-Garcia, Talitha Schorb, José S Ramalho, Vladimir M Milenkovic, Renate Föckler, Miguel C Seabra, Olaf Strauss

Journal, date & volume: Cell. Signal., 2015 Nov , 27, 2231-40

PubMed link: http://www.ncbi.nlm.nih.gov/pubmed/26235199

Abstract
In a variety of cells, secretory processes require the activation of both Rab27a and L-type channels of the Ca(V)1.3 subtype. In the retinal pigment epithelium (RPE), Rab27a and Ca(V)1.3 channels regulate growth-factor secretion towards its basolateral side. Analysis of murine retina sections revealed a co-localization of both Rab27a and Ca(V)1.3 at the basolateral membrane of the RPE. Heterologously expressed Ca(V)1.3/β3/α2δ1 channels showed negatively shifted voltage-dependence and decreased current density of about 70% when co-expressed with Rab27a. However, co-localization analysis using α(5)β(1) integrin as a membrane marker revealed that Rab27a co-expression reduced the surface expression of Ca(V)1.3 only about 10%. Physical binding of heterologously expressed Rab27a with Ca(V)1.3 channels was shown by co-localization in immunocytochemistry as well as co-immunoprecipitation which was abolished after deletion of a MyRIP-homologous amino acid sequence at the II-III linker of the Ca(V)1.3 subunit. Rab27a over-expression in ARPE-19 cells positively shifted the voltage dependence, decreased current density of endogenous Ca(V)1.3 channels and reduced VEGF-A secretion. We show the first evidence of a direct functional modulation of an ion channel by Rab27a suggesting a new mechanism of Rab and ion channel interaction in the control of VEGF-A secretion in the RPE.