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This Article Accepted manuscript (PDF) All Versions of this Article: JOE-07-0570v1 198/1/193    most recent Alert me when this article is cited Alert me if a correction is posted Services Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via Google Scholar Google Scholar Articles by Azhar, S. Articles by Shen, W.-j. Search for Related Content PubMed PubMed Citation Articles by Azhar, S. Articles by Shen, W.-j.

S Azhar, VA Palo Alto Health Care System, GRECC-182B, Palo Alto, 94304, United States
P Abidi, GRECC, VA Palo Alto Health Care System, Palo Alto, United States
S Leers-Sucheta, GRECC, VA Palo Alto Health Care System, Palo Alto , United States
Y Cortez, GRECC, VA Palo Alto, Palo Alto, United States
J Han, Department of Immunology, The Scripps Research Institute, La Jolla, United States
H Zhang, GRECC, VA Palo Alto Health Care System, Palo Alto, United States
S Zaidi, Palo Alto, United States
W Shen, Palo Alto, United States

Correspondence: Salman Azhar, Email: salman.azhar{at}va.gov

Abstract

Previous studies from this laboratory identified excessive oxidative stress as an important mediator of age-related decline in steroid hormone production. Here, we investigated whether oxidative stress exerts its anti-steroidogenic action through modulation of oxidant-sensitive MAPK signaling pathways. To accomplish these studies, we employed a highly responsive mouse adrenocortical cell line, Y1-BS1 cells which secrete large quantities of steroids when stimulated with lipoprotein plus hormone. Treatment of these cells with superoxide, H2O2 or HNE significantly inhibited steroid production. Such treatments also resulted in increased phosphorylation and activation of p38 MAPK. None of the treatments altered the phosphorylation of either ERKs or JNKs. Pretreatment of Y1-BS1 cells with MnTMPyP, a cell-permeable superoxide-dismutase/catalase mimetic (ROS scavenger), completely prevented the superoxide and H2O2-mediated inhibition of steroid production. Likewise, antioxidant NAC fully blocked the HNE-induced loss of steroidogenic response. Inhibition of p38 MAPK with SB203580 or SB202190 upregulated the basal steroid production and also prevented the oxidant-mediated inhibition of steroid production. Transfection of Y1-BS1 cells with either caMKK3 or caMMK6 construct, the upstream p38 MAPK activators, decreased steroidogenesis, whereas transfection with dnMKK3 or dnMKK6 plasmid DNA increased steroidogenesis. Similarly, transfection of cells with a dnp38 MAPKalpha or dnp38 MAPKbeta construct also increased the steroid hormone production; the expression of either dnp38 MAPKgamma or dnp38 MAPKgamma, however, resulted in less stimulation. These results indicate that activated p38 MAPK mediates oxidant (excessive oxidative stress)-induced inhibition of adrenal steroidogenesis.