Coupling of Integrin α5 to Annexin A2 by Flow Drives Endothelial Activation

Abstract

Rationale: Atherosclerosis preferentially occurs at specific sites of the vasculature where endothelial cells (ECs) are exposed to disturbed blood flow. Translocation of integrin α5 to lipid rafts promotes integrin activation and ligation, which is critical for oscillatory shear stress (OSS)-induced EC activation. However, the underlying mechanism of OSS promoted integrin α5 lipid raft translocation has remained largely unknown. Objective: The objective of this study was to specify the mechanotransduction mechanism of OSS-induced integrin α5 translocation and subsequent EC activation. Methods and Results: Mass spectrometry studies identified endothelial ANXA2 (annexin A2) as a potential carrier allowing integrin α5β1 to traffic in response to OSS. Interference by siRNA of AnxA2 in ECs greatly decreased OSS-induced integrin α5β1 translocation to lipid rafts, EC activation, and monocyte adhesion. Pharmacological and genetic inhibition of PTP1B (protein tyrosine phosphatase 1B) blunted OSS-induced integrin α5β1 activation, which is dependent on Piezo1-mediated calcium influx in ECs. Furthermore, ANXA2 was identified as a direct substrate of activated PTP1B by mass spectrometry. Using bioluminescence resonance energy transfer assay, PTP1B-dephosphorylated ANXA2 at Y24 was found to lead to conformational freedom of the C-terminal core domain from the N-terminal domain of ANXA2. Immunoprecipitation assays showed that this unmasked ANXA2-C-terminal core domain specifically binds to an integrin α5 nonconserved cytoplasmic domain but not β1. Importantly, ectopic lentiviral overexpression of an ANXA2 Y24F mutant increased and shRNA against Ptp1B decreased integrin α5β1 ligation, inflammatory signaling, and progression of plaques at atheroprone sites in apolipoprotein E ( ApoE ) −/− mice. However, the antiatherosclerotic effect of Ptp1B shRNA was abolished in AnxA2 −/− ApoE −/− mice. Conclusions: Our data elucidate a novel endothelial mechanotransduction molecular mechanism linking atheroprone flow and activation of integrin α5β1, thereby identifying a class of potential therapeutic targets for atherosclerosis. Graphic Abstract: An graphic abstract is available for this article.

Platelet-Derived Extracellular Vesicles Increase Col8a1 Secretion and Vascular Stiffness in Intimal Injury

“…Mechano-homeostasis plays a key role in maintaining the biological functions of the cardiovascular system and the pathological development of cardiovascular disease (Chien, 2007;Haga et al, 2007). A variety of mechanical stresses change, coordinate and control a variety of vascular cells, including ECs and vascular smooth muscle cells (VSMCs) (Tanaka et al, 2019;Zhang et al, 2020;Ngai et al, 2020). Therefore, exploring the changes in the mechanical stress that arterial cells are subjected to is crucial to understanding the mechanobiological mechanisms underlying vascular cell dysfunction.…”

Annexin A2 in Fibrinolysis, Inflammation and Fibrosis

“…In addition, a recent study showed that mechanical stress on endothelial cells may lead to atherosclerosis through an interaction between intracellular A2 and integrin α5. Disturbed flood flow with oscillatory stress on endothelial cells accelerated the dephosphorylation of A2, which facilitated the binding of integrin α5 to the C-terminal domain of A2, thereby activating integrin α5β1, and leading to the progression of atherosclerosis [37,38]. Mechanisms of A2-mediated hemostasis and vascular homeostasis are summarized in Figure 1.…”

Roles of Membrane Domains in Integrin-Mediated Cell Adhesion

“…Clustering of ganglioside-enriched lipid rafts regulate the activity of integrin β1 [ 119 ]. Further, integrin α5 was found to be the protein most elevated from lipid rafts of endothelial cells that was exposed to oscillatory shear stress, which also increased the level of activated integrin α5 regulated by membrane cholesterol and fluidity [ 120 , 121 ]. Lipid raft molecules dissociate upon cholesterol removal [ 122 ].…”