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(Arteriosclerosis, Thrombosis, and Vascular Biology. 2009;29:387.)
© 2009 American Heart Association, Inc.

Cell Biology/Signaling

Role of Src Tyrosine Kinase in the Atherogenic Effects of the 12/15-Lipoxygenase Pathway in Vascular Smooth Muscle Cells

Marpadga A. Reddy; Saurabh Sahar; Louisa M. Villeneuve; Linda Lanting; Rama Natarajan

From the Division of Diabetes (M.A.R., S.S., L.M.V., L.L., R.N.) and the Graduate School of Biological Sciences (S.S., L.M.V., R.N.), Beckman Research Institute of the City of Hope, Duarte, Calif.

Correspondence to Prof Rama Natarajan, PhD, Gonda Diabetes Research Center, Beckman Research Institute of the City of Hope, 1500 East Duarte Road, Duarte, CA 91010. E-mail RNatarajan{at}coh.org

Objective— The 12/15-Lipoxygenase (12/15-LO) and its metabolite 12(S)-Hydroxyeicosatetraenoic acid [12(S)-HETE] mediate proatherogenic responses in vascular smooth muscle cells (VSMCs). We examined the role of the nonreceptor tyrosine kinase Src in the signaling and epigenetic chromatin mechanisms involved in these processes.

Methods and Results— Rat VSMCs (RVSMCs) were stimulated with 12(S)-HETE (0.1 µmol/L) in the presence or absence of the Src inhibitor PP2 (10 µmol/L). Src activation and downstream signaling events including inflammatory gene expression and chromatin histone H3-Lys-9/14 acetylation were examined by immunoblotting, RT-PCR, and chromatin immunoprecipitation assays, respectively. 12(S)-HETE significantly activated Src, focal adhesion kinase, Akt, p38MAPK, and CREB. Expression of monocyte chemoattractant protein-1 and interleukin-6 genes and histone H3-Lys-9/14 acetylation on their promoters were also increased by 12(S)-HETE. PP2 inhibited these responses as well as 12(S)-HETE-induced VSMC migration. Furthermore, dominant negative mutants of Src, CREB, and a histone acetyltransferase p300 significantly blocked 12(S)-HETE–induced inflammatory gene expression. In addition, growth factor induced Src signaling and downstream events including H3-Lys-9/14 acetylation and migration were significantly attenuated in VSMCs derived from 12/15-LO^–/– mice relative to WT.

Conclusions— Src kinase signaling plays a central role in the proatherogenic responses mediated by 12/15-LO and its oxidized lipid metabolite 12(S)-HETE in VSMCs.

Key Words: Oxidized lipids • vascular biology • 12/15-lipoxygenase • Src kinase • histone acetylation • atherosclerosis • inflammatory genes