Mechanisms of induction of endothelial cell E-selectin expression by smooth muscle cells and its inhibition by shear stress

E-selectin is a major adhesion molecule expressed by endothelial cells (ECs), which are exposed to shear stress and neighboring smooth muscle cells (SMCs). We investigated the mechanisms underlying the modulation of EC E-selectin expression by SMCs and shear stress. SMC coculture induced rapid and sustained increases in expression of E-selectin and phosphorylation of interleukin-1 (IL-1) receptor-associated kinase and glycoprotein-130, as well as the downstream mitogen-activated protein kinases (MAPKs) and Akt. By using specific inhibitors, dominant-negative mutants, and small interfering RNA, we demonstrated that activations of c-Jun-NH₂-terminal kinase (JNK) and p38 of the MAPK pathways are critical for the coculture-induced E-selectin expression. Gel shifting and chromatin immunoprecipitation assays showed that SMC coculture increased the nuclear factor-κB (NF-κB)-promoter binding activity in ECs; inhibition of NF-κB activation by p65-antisense, lactacystin, and N-acetyl-cysteine blocked the coculture-induced E-selectin promoter activity. Protein arrays and blocking assays using neutralizing antibodies demonstrated that IL-1β and IL-6 produced by EC/SMC cocultures are major contributors to the coculture induction of EC signaling and E-selectin expression. Preshearing of ECs at 12 dynes/cm² inhibited the coculture-induced EC signaling and E-selectin expression. Our findings have elucidated the molecular mechanisms underlying the SMC induction of EC E-selectin expression and the shear stress protection against this SMC induction.