STIM1 in Rat Ventricular Myocytes

Abstract

The Ca2+ binding protein STIM1 is located primarily in the sarcoplasmic and endoplasmic reticulum. It is thought that STIM1 plays a critical role in activating Ca2+ release activated Ca2+ channel (CRAC) in non-excitable cells such as T lymphocytes and may also be important in excitable cells such as skeletal muscle and smooth muscle cells. However, it is not clear yet if STIM1 is expressed and functions in adult rat ventricular myocytes. Figure A shows STIM1 immunofluorescence and Figure B shows STIM1-mcherry fluorescence expressed in cultured rat ventricular myocytes. Both show a similar pattern of STIM1 localization, primarily at the Z-disk of the ventricular myocyte. Fluorescence recovery after photobleaching shows that STIM1 moves readily with the S/ER network. While there is no obvious need for store-operated Ca2+ channels (SOCs) in ventricular myocytes, the clear presence of STIM1 suggests that an as yet undiscovered function of this Ca2+ binding protein in ventricular myocytes is likely to be discovered. We are now examining the electrophysiological and Ca2+ signaling functions of STIM1 in mammalian (rat and mouse) ventricular myocytes.View Large Image | View Hi-Res Image | Download PowerPoint Slide