Upregulation of angiotensin converting enzyme 2 by shear stress reduced inflammation and proliferation in vascular endothelial cells

Abstract Background Shear stress (SS) and renin-angiotensin system (RAS) play important roles in endothelium homeostasis. Previous studies demonstrated that pulsatile shear stress (PSS) reduced the expression and activity of angiotensin-converting enzyme (ACE), however, the effect of SS on angiotensin-converting enzyme 2 (ACE2) expression is unclear. Methods and results We exposed cultured endothelial cells (ECs) to distinct patterns of SS for indicated time points, Western blot and RT-PCR were used to determine the ACE2 expression; En Face staining was used to detect ACE2 expression in vivo; cell proliferation and apoptosis were determined by BrdU staining and TUNEL staining, respectively; the production of NO was detected by a commercial kit; the promoter activity of ACE2 was determined by a Dual-Luciferase Reporter Assay System, inhibitors of ACE2 and signaling pathway were added to the medium 1 h prior for PSS. Our data showed PSS induced a sustained ACE2 expression, but OSS only induced a transient ACE2 expression. The PSS-induced ACE2 expression was higher than that of OSS both in vitro and in vivo. The PSS-induced ACE2 was involved in inhibiting proliferation and inflammation, as well as promoting NO production in ECs. PSS significantly increased ACE2 expression at transcriptional level via activating AMPKα2-KLF2 pathway. Conclusions Our results suggest PSS promotes ACE2 expression via AMPKα2-KLF2 pathway to maintain the normal EC functions.