Knockdown of sestrin2 increases pro-inflammatory reactions and ER stress in the endothelium via an AMPK dependent mechanism

Abstract

Background & objective: Sestrin2 (sesn2) has recently gained attention as an important regulator for various metabolic disorders. Sesn2 is involved in AMP-activated protein kinase (AMPK) activation, which leads to anti-inflammatory and anti-oxidative responses. However, the role of sesn2 in the endothelium has not yet been clarified.

Methods: To evaluate sesn2-mediated anti-atherosclerotic effects, siRNA to silence sesn2 expression was introduced to human umbilical vein endothelial cells (HUVECs), THP-1 cells and C57BL/6 mice. Lipopolysaccharide (LPS) was administrated to sesn2-knockdown cells and mice to induce atherosclerotic signals.

Results: Knockdown of sesn2 was involved with atherosclerotic reactions caused by LPS treatment through decrease of AMPK phosphorylation. In sesn2-knockdown HUVECs and THP-1 cells, LPS-mediated nuclear factor kappa B (NF-κB) phosphorylation and secretion of pro-inflammatory cytokines were both significantly increased. In HUVECs, expression of adhesion molecules and LPS-stimulated adhesion of THP-1 cells to the endothelium were significantly increased after sesn2-knockdown. Furthermore, LPS-induced reactive oxygen species (ROS) production, endoplasmic reticulum (ER) stress, and cell toxicity were all significantly elevated after sesn2-knockdown in HUVECs. Interestingly, all these pro-atherosclerotic effects were fully abrogated by treatment with an AMPK activator. In aortic tissue samples from C57BL/6 mice, sesn2-knockdown using siRNA oligomers resulted in reduced AMPK phosphorylation and induction of LPS-mediated NF-κB phosphorylation, leading to up-regulation of adhesion molecules and ER stress-related signaling.

Conclusion: Knockdown of sesn2 aggravates atherosclerotic processes by increasing pro-inflammatory reactions and ER stress in the endothelium via an AMPK-dependent mechanism, suggesting that sesn2 might be a novel therapeutic target for atherosclerosis.

Keywords: AMPK; Atherosclerosis; ER stress; Endothelium; Pro-inflammatory reactions; Sesn2.