"Expression of Estrogen receptor beta in C2C12 cell line and murine skeletal muscle tissue: Comparison of subcellular distribution with the native estrogen receptor alpha"

LORENA MILANESI; ANDREA VASCONSUELO; ANA RUSSO DE BOLAND; RICARDO BOLAND

STEROIDS

ELSEVIER SCIENCE INC

Año: 2009 vol. 74 p. 489 - 497

0039-128X

We have recently described the expression and intracellular localization of ER a in murine C2C12 cells and skeletal muscle tissue. In separate studies, a protective role of 17 b -estradiol against apoptosis exerted mainly at the mitochondrial level was also shown in the C2C12 muscle cell line. However, this functional evidencewas in accordance with the participation of ER b .We have then here investigated the expression and subcellular distribution of native ER b in similar skeletal muscle cultured cells and tissue developed in vivo. ER b was detected by immunoblotting using specific antibodies and ligand blot analysis after subcellular fractionation. Immunolocalization was confirmed using conventional and confocal microscopy. ER b was found to a great extent in mitochondria and in lower amounts in the cytosolic fraction, differently to ER b which localizes in microsomes, cytosol, mitochondria, and also in the nucleus of muscle tissue. ER bexpression was also demonstrated by RT-PCR. Finally, the mitochondrial localization of native ER b in C2C12 muscle cells was corroborated after transient transfection with specific ER b siRNAs. These data raise the possibility that the antiapoptotic action of 17b-estradiol in muscle cells may be related in part to a direct action of the hormone on mitochondria through ER b .