Mitochondrial dysfunction has been linked to etiology of insulin resistance, however the mechanism remains unknown. In this study we investigated whether mitochondrial dysfunction induced by cyanide p-trifluoromethoxyphenyl-hydrazone (FCCP) alters insulin sensitivity in 3T3-L1 adipocytes and which cellular signaling molecules might be involved. Fully differentiated 3T3-L1 adipocytes were treated with 10 mu M FCCP for 1 h, resulting in increased serine-307 phosphorylation of IRS-1 and decreased insulin-stimulated tyrosine phosphorylation, association of p85 alpha subunit of phosphatidylinositol 3-kinase (PI 3-kinase) with IRS-1, decreased insulin-stimulated PI 3-kinase activity and H-3-2-deoxyglucose (2DOG) uptake. A partial (46%) knockdown of JNK1 blocked FCCP-induced serine phosphorylation of IRS-1 and restored insulin-stimulated tyrosine phosphorylation of IRS-1, association of p85 alpha subunit of PI 3-kinase with IRS-1. activation of PI 3-kinase, and stimulation of 2DOG uptake. Thus, FCCP-induced mitochondrial dysfunction may cause insulin resistance that is ameliorated by reduction of JNK1 expression. (C) 2008 Elsevier Inc. All rights reserved.