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(Circulation Research. 2008;102:538.)
© 2008 American Heart Association, Inc.

Molecular Medicine

Extracellular Signal-Regulated Kinase 5 SUMOylation Antagonizes Shear Stress–Induced Antiinflammatory Response and Endothelial Nitric Oxide Synthase Expression in Endothelial Cells

Chang-Hoon Woo, Tetsuro Shishido, Carolyn McClain, Jae Hyang Lim, Jian-Dong Li, Jay Yang, Chen Yan, Jun-ichi Abe

From the Cardiovascular Research Institute (C.-H.W., T.S., C.M., C.Y., J.-i.A.) and Department of Microbiology and Immunology (J.H.L., J.-D.L.), University of Rochester; and Department of Anesthesiology (J.Y.), Columbia University, New York.

Correspondence to Jun-ichi Abe, MD, PhD, Cardiovascular Research Institute, Box 679, 601 Elmwood Ave, University of Rochester School of Medicine and Dentistry, Rochester, NY 14642. E-mail Jun-ichi_Abe{at}urmc.rochester.edu

Shear stress–induced extracellular signal-regulated kinase (ERK)5 activation and the consequent regulation of Kruppel-like factor 2 and endothelial nitric oxide synthase expression represents one of the antiinflammatory and vascular tone regulatory mechanisms maintaining normal endothelial function. Endothelial dysfunction is a major initiator of atherosclerosis, a vascular pathology often associated with diabetes. Small ubiquitin-like modifier (SUMO) covalently attaches to certain residues of specific target transcription factors and could inhibit its activity. We investigated whether H₂O₂ and AGE (advanced glycation end products), 2 well-known mediators of diabetes, negatively regulated ERK5 transcriptional activity and laminar flow–induced endothelial nitric oxide synthase expression through ERK5 SUMOylation. H₂O₂ and AGE induced endogenous ERK5 SUMOylation. In addition, ERK5 SUMOylation was increased in the aortas from diabetic mice. ERK5 transcriptional activity, but not kinase activity, was inhibited by expression of Ubc9 (SUMO E2 conjugase) or PIAS1 (E3 ligase), suggesting the involvement of ERK5 SUMOylation on its transcriptional activity. Point-mutation analyses showed that ERK5 is covalently modified by SUMO at 2 conserved sites, Lys6 and Lys22, and that the SUMOylation defective mutant of ERK5, dominant negative form of Ubc9 (DN-Ubc9), and small interfering RNA PIAS1 reversed H₂O₂ and AGE–mediated reduction of shear stress–mediated ERK5/myocyte enhancer factor 2 transcriptional activity, as well as promoter activity of Kruppel-like factor 2. Finally, PIAS1 knockdown reversed the inhibitory effect of H₂O₂ in shear stress–induced Kruppel-like factor 2 and endothelial nitric oxide synthase expression. These data clearly defined SUMOylation-dependent ERK5 transcriptional repression independent of kinase activity and suggested this process as among the molecular mechanisms of diabetes-mediated endothelial dysfunction.

Key Words: ERK5 • SUMOylation • KLF2 • diabetes • shear stress

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				I. R. Buschmann, K. Lehmann, F. Le Noble, and on behalf of Art.Net. Physics Meets Molecules: Is Modulation of Shear Stress the Link to Vascular Prevention? Circ. Res., March 14, 2008; 102(5): 510 - 512. [Full Text] [PDF]