Back
Acta Physiologica 2008; Volume 192, Supplement 662
Belgian Society for Fundamental and Clinical Physiology and Pharmacology, Autumn Meeting 2007
11/17/2007-11/17/2007
Katholieke Universiteit Leuven, Leuven, Belgium
SIGMA-1 RECEPTOR DOES NOT AFFECT INSP3 INDUCED CA2+ SIGNALS IN HEPATOCYTES
Abstract number: P-03
Abou-Lovergne1 A., Koukoui1 O., Hilly1 M., Prigent1 S., Monnet1 FP., Combettes1 L.
1INSERM UMR-S U757, Universit Paris-Sud, Bt 443, 91405 Orsay, France
Changes in cytosolic Ca2+ concentration are critical for numerous hepatocyte functions. While it is well-known that InsP3 receptors (InsP3-Rs) play a crucial role in this process, the regulation of the three types of InsP3 receptors by other proteins remains largely unknown. It has been shown in neuroblastoma cells that sigma-1 receptor (s1-R) could interact with InsP3 receptors and affect Ca2+ signaling. The sigma-1 receptors, initially described as a subtype of opiate receptors, is highly expressed in the central nervous system and in the liver. We thus examined whether sigma-1 receptors could be involved in the regulation of Ca2+ signaling in hepatocytes.
Subcellular fractionation of liver membranes shown that s1-R and InsP3T1-R were distributed in all fractions analyzed. In contrast InsP3T2-R was found in a particular fraction enriched with markers of baso-lateral membranes. Immunofluorescence experiments confirm these observations. InsP3T2-R was concentrated near the canalicular pole in hepatocytes, whereas InsP3T1-R and s1-R were found to be homogeneously distributed within the cytosol. Specific s1-R ligands inhibited noradrenaline induced Ca2+ increase but did not modify InsP3 induced Ca2+ release in permeabilized hepatocytes. Moreover, intracellular Ca2+ signals were not affected by the overexpression of s1-R in HepG2 cells. Our results suggest that s1-R is not involved in the regulation of InsP3 induced Ca2+ signals in hepatocytes.
To cite this abstract, please use the following information:
Acta Physiologica 2008; Volume 192, Supplement 662 :P-03