Title

Role of wild-type estrogen receptor-β in mitochondrial cytoprotection of cultured normal male and female human lens epithelial cells

Document Type

Journal Article

Publication Date

9-1-2008

Journal

American Journal of Physiology - Endocrinology and Metabolism

Volume

295

Issue

3

DOI

10.1152/ajpendo.90407.2008

Abstract

The influence of sexual category as a modifier of cellular function is underinvestigated. Whether sex differences affect estrogen-mediated mitochondrial cytoprotection was determined using cell cultures of normal human lens epithelia (nHLE) from postmortem male and female donors. Experimental indicators assessed included differences in estrogen receptor-β (ERβ) isoform expression, receptor localization in mitochondria, and estrogen-mediated prevention of loss of mitochondrial membrane potential using the potentiometric fluorescent compound JC-1 after nHLE were exposed to peroxide. The impact of wild-type ERβ (wtERβ1) was also assessed using wtERβ1 siRNA to suppress expression. A triple-primer PCR assay was employed to determine the proportional distribution of the receptor isoforms (wtERβ1, -β2, and -β5) from the total ERβ message pool in male and female cell cultures. Irrespective of sex, nHLE express wtERβ1 and the ERβ2 and ERβ5 splice variants in similar ratios. Confocal microscopy and immunofluorescence revealed localization of the wild-type receptor in peripheral mitochondrial arrays and perinuclear mitochondria as well as nuclear staining in both cell populations. The ERβ2 and ERβ5 isoforms were distributed primarily in the nucleus and cytosol, respectively; no association with the mitochondria was detected. Both male and female nHLE treated with E2 (1 μM) displayed similar levels of protection against peroxideinduced oxidative stress. In conjunction with acute oxidative insult, RNA suppression of wtERβ1 elicited the collapse of mitochondrial membrane potential and markedly diminished the otherwise protective effects of E2. Thus, whereas the estrogen-mediated prevention of mitochondrial membrane permeability transition is sex independent, the mechanism of estrogen-induced mitochondrial cytoprotection is wtERβ1 dependent. Copyright © 2008 the American Physiological Society.

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