Profilin acts downstream of LDL to mediate diabetic endothelial cell dysfunction

The changes occurring at the luminal surface of endothelial cells in diabetes and their relevance to endothelial dysfunction are poorly characterized in vivo. In this study, we developed an integrated strategy to discover cell surface proteins associated with diabetes and to test their role in endothelial dysfunction. First, a peptide phage display library was screened over the endothelial surface of the intact aorta or in retinal endothelial cells from diabetic and control rats. Then, we purified profilin-1 as a binding partner for one of the diabetic aorta-specific phage. Profilin was increased in the aortic endothelium of human diabetic individuals and streptozotocin-diabetic rats. Furthermore, overexpressing profilin in rat aortic endothelial cells triggered 3 indicators of endothelial dysfunction: increased apoptosis, elevated expression of ICAM-1, and decreased phosphorylation of the vasodilator-stimulated phosphoprotein, a marker for nitric oxide signaling. The changes in ICAM-1 and vasodilator-stimulated phosphoprotein were recapitulated in the diabetic aorta in vivo. LDL and oxysterols elevated profilin in cultured aortic endothelial cells. Interference with the de novo synthesis of profilin abrogated the LDL-mediated increase in ICAM-1 expression. Finally, profilin expression was markedly elevated in atherosclerotic plaques. These data indicate that profilin contributes to endothelial dysfunction in a pathway that is downstream of LDL.