No abstract

YAP binding sustained STAT3 in the nucleus to enhance the latter's transcriptional activity and promote angiogenesis via regulation of angiopoietin-2.

Highlights d Myeloid-specific overexpression of YAP promotes the development of atherosclerosis d IL-1b induces macrophage YAP nuclear localization and protein stability d Macrophage YAP regulates chemokine production and monocyte/macrophage recruitment d Macrophage YAP is upregulated in patients and mouse atherosclerotic lesions

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.

Endothelial cells regulate vascular tone by producing both relaxing and contracting factors to control the local blood flow. Hypertension is a common side effect of mTORC1 (mammalian target of rapamycin complex 1) inhibitors. However, the role of endothelial mTORC1 in hypertension remains elusive. The present study aimed to determine the role of endothelial mTORC1 in Ang II (angiotensin II)–induced hypertension and the underlying mechanism. Endothelial mTORC1 activity was increased by Ang II both in vitro and in vivo. Blood pressure was higher in Tie-2-Cre –mediated regulatory associated protein of mTOR (mammalian target of rapamycin; Raptor ) heterozygous-deficient ( Tie2Cre-Raptor KD ) mice than control mice both before and after Ang II infusion. Acetylcholine-evoked endothelium-dependent relaxation of mesenteric arteries was impaired in Tie2Cre-Raptor KD mice. Treatment with indomethacin or a specific COX (cyclooxygenase)-2 inhibitor, NS-398, but not L-NG-nitroarginine methyl ester reduced endothelium-dependent relaxation in Raptor flox /− mice to a similar extent as in Tie2Cre-Raptor KD mice. Metabolomic profiling revealed that the plasma content of prostaglandin E 2 was reduced in Tie2Cre-Raptor KD mice with or without Ang II infusion. In endothelial cells, reduction of the protein level of YAP (yes-associated protein) with siRNA -mediated RPTOR deficiency was autophagy dependent and transcriptionally regulated the expression of COX-2 and mPGES-1 (microsomal prostaglandin E synthase-1). Hence, overexpression of YAP in endothelial cells enhanced the mRNA and protein levels of COX-2 and mPGES-1 and reversed the endothelial dysfunction and hypertension in Tie2Cre-Raptor KD mice. The present results demonstrate that suppression of mTORC1 activity in endothelial cells reduces prostaglandin E 2 production and causes hypertension by reducing YAP-mediated COX-2/mPGES-1 expression.

Rationale Circulating monocytes play pivotal roles in chronic inflammatory diseases. Epoxyeicosatrienoic acids (EETs), metabolites of arachidonic acid, are known to have anti-inflammatory effects and are hydrolyzed by soluble epoxide hydrolase (sEH). Objective We aimed to investigate the effect of sEH inhibition in atherogenesis. Methods and Results Mice with low-density lipoprotein receptor deficiency (Ldlr−/−) with or without sEH inhibitor, and Ldlr/sEH double-knockout (DK) mice were fed a Western-type diet (WTD) for 6 weeks to induce arteriosclerosis. Both sEH inhibition and gene depletion decreased the WTD–induced hyperlipidemia, plaque area and macrophage infiltration in mice arterial wall. Ly6Chi infiltration of monocytes remained similar in blood, spleen and bone marrow of DK mice, but was decreased in aortic lesions. To further assess the role of sEH or EETs in monocyte/macrophage infiltration in atherogenesis, we transplanted DK bone marrow into Ldlr−/− recipients, and then fed mice the WTD. Aortic lesions and Ly6Chi monocyte infiltration were reduced in mice with transplanted bone marrow of DK mice without diminishing the cholesterol level. Furthermore, sEH inhibition or gene depletion increased the ratio of EETs/DHETs and diminished the expression of P-selectin glycoprotein ligand 1 (PSGL-1) in mice peripheral-blood mononuclear cells. Monocyte adhesion to P-selectin and to tumor necrosis factor α–activated endothelial cells was also diminished by sEH inhibition. Conclusion sEH inhibition and gene depletion attenuated atherosclerosis in mice by decreasing the infiltration of monocytes into the artery wall. EET and PSGL-1 may play pivotal roles in monocyte/macrophage infiltration and atherogenesis.

Rationale: Timely inhibition of inflammation and initiation of resolution are important to repair injured tissues. Mammalian STE20-like protein kinase 1/2 (MST1/2) acts as a regulator of macrophage-associated immune responses to bacterial infections. However, the role of MST1/2 in regulating macrophage phenotype and function in myocardial infarction (MI) remains unclear. Objective: To determine the function and underlying mechanism of macrophage MST1/2 in cardiac repair post-MI. Methods and Results: Using LysMCre-mediated Mst1/2-deficient mice, we found that MST1 deficiency exacerbated cardiac dysfunction after MI. Single-cell RNA sequencing assay indicated that the effect was attributed to a shift of macrophage subtypes from those expressing Cxcl2 and Cd163 toward Ccl2 and Ccl4 expression. Mass spectrometry identified leukotriene B4 (LTB4) as the lipid mediator that was upregulated in the absence of MST1. We found that MST1 phosphorylated 5-lipoxygenase (5-LOX) at its T218 residue, disrupting the interaction between 5-LOX and 5-LOX-activating protein, resulting in a reduction of LTB4 production. In contrast, a 5-LOXT218A variant showed no response to MST1. Moreover, treatment of peritoneal macrophages with LTB4 or medium conditioned by Mst1-deficient macrophages resulted in high Ccl2 and Ccl4 expression and low Cxcl2 and Cd163 expression, except when the cells were co-treated with the LTB4 receptor 1 (BLT1) antagonist CP105696. Furthermore, CP105696 ameliorated cardiac dysfunction in LysMCre-mediated Mst1/2-deficient mice and enhanced cardiac repair in wild-type mice treated with XMU-MP-1 after MI. Conclusions: Taken together, our results demonstrate that inhibition of MST1/2 impaired post-MI repair through activating macrophage 5-LOX-LTB4-BLT1 axis.

Background: Vascular endothelial cells are critical for maintaining blood pressure (BP) by releasing biologically active molecules, such as nitric oxide. A non-endothelial cell resident matricellular protein, COMP (cartilage oligomeric matrix protein), plays a pivotal role in maintaining cardiovascular homeostasis, but little is known about its regulatory effect on BP. Methods: Mice were infused with AngII (angiotensin II; 450 ng/kg per minute) for 3 days via an osmotic minipump, and BP was monitored by a tail-cuff system. Second-order mesenteric arteries were isolated from mice for microvascular tension measurement. Nitric oxide was detected by an electron paramagnetic resonance technique. Small-interfering RNA transfection, co-immunoprecipitation, bioluminescence resonance energy transfer assays, and patch-clamp electrophysiology experiments were used for further detailed mechanism investigation. Results: COMP −/− mice displayed elevated BP and impaired acetylcholine-induced endothelium-dependent relaxation compared with wild-type mice with or without AngII. Inhibition of eNOS (endothelial nitric oxide synthase) abolished the difference in endothelium-dependent relaxation between wild-type and COMP −/− mice. Furthermore, COMP directly interacted with the C-terminus of Piezo1 via its C-terminus and activated the endogenous Piezo1 currents, which induced intracellular Ca 2+ influx, Ca 2+ /calmodulin-dependent protein kinase type II and eNOS activation, and nitric oxide production. The Piezo1 activator, Yoda1, reduced the difference in endothelium-dependent relaxation and BP in wild-type and COMP − /− mice. Moreover, COMP overexpression increased eNOS activation and improved endothelium-dependent relaxation and BP. Conclusions: Our study demonstrated that COMP is a novel Piezo1 regulator that plays a protective role in BP regulation by increasing cellular Ca 2+ influx, eNOS activity, and nitric oxide production.