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RNA Suppression of ERK2 Leads to Collapse of Mitochondrial Membrane Potential with Acute Oxidative Stress in Human Lens Epithelial Cells
Publication year - 2008
Publication title -
the faseb journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.709
H-Index - 277
eISSN - 1530-6860
pISSN - 0892-6638
DOI - 10.1096/fasebj.22.1_supplement.981.1
Subject(s) - depolarization , phosphorylation , microbiology and biotechnology , small interfering rna , inner mitochondrial membrane , mitochondrion , oxidative stress , membrane potential , oxidative phosphorylation , biology , kinase , phosphorylation cascade , chemistry , protein kinase a , protein phosphorylation , biochemistry , biophysics , transfection , gene
17‐β estradiol (E 2 ) reduces oxidative stress‐induced depolarization of mitochondrial membrane potential (MMP) in cultured human lens epithelial cells (HLE‐B3). The mechanism by which non‐genomic effects of E 2 contributed to the protection against mitochondrial membrane depolarization was investigated. Mitochondrial membrane integrity is regulated by phosphorylation of BAD and it is known that phosphorylation of Ser‐112 inactivates BAD and prevents its participation in the mitochondrial death pathway. We found that E 2 rapidly increased both the phosphorylation of extracellular signal‐regulated kinase 2 (ERK2) and Ser‐112 in BAD. Ser‐112 is phosphorylated by RSK, a Ser/Thr kinase, which is a downstream effector of ERK1/2. Inhibition of RSK by the RSK‐specific inhibitor, SL0101, did not reduce the level of E 2 ‐induced phosphorylation of Ser‐112, suggesting a RSK independent pathway for Ser‐112 BAD phosphorylation. Silencing BAD using small interfering RNA (siRNA) did not reduce mitochondrial membrane depolarization elicited by peroxide insult. However, under the same conditions, silencing ERK2 dramatically increased membrane depolarization compared to the control siRNA. Therefore, ERK2, functioning through a BAD‐independent mechanism, regulates MMP in humans lens epithelial cells. We propose that estrogen‐induced activation of ERK2 acts to protect cells from acute oxidative stress.