MST1 Suppresses Disturbed Flow Induced Atherosclerosis.

BACKGROUND: Atherosclerosis occurs mainly at arterial branching points exposed to disturbed blood flow. How MST1 (mammalian sterile 20-like kinase 1), the primary kinase in the mechanosensitive Hippo pathway modulates disturbed flow induced endothelial cells (ECs) activation and atherosclerosis remains unclear. METHODS: To assess the role of MST1 in vivo, mice with EC-specific Mst1 deficiency on ApoE-/- background (Mst1iECKOApoE-/-) were used in an atherosclerosis model generated by carotid artery ligation. Mass spectrometry, immunoprecipitation, proximity ligation assay, and dye uptake assay were used to identify the functional substrate of MST1. Human umbilical vein endothelial cells and human aortic endothelial cells were subjected to oscillatory shear stress that mimic disturbed flow in experiments conducted in vitro. RESULTS: We found that the phosphorylation of endothelial MST1 was significantly inhibited in oscillatory shear stress-exposed regions of human and mouse arteries and ECs. Ectopic lenti-mediated overexpression of wild-type MST1, but not a kinase-deficient mutant of MST1, reversed disturbed flow-caused EC activation and atherosclerosis in EC-specific Mst1 deficiency on ApoE-/- background (Mst1iECKOApoE-/-). Inhibition of MST1 by oscillatory shear stress led to reduced phosphorylation of Cx43 (connexin 43) at Ser255, the Cx43 hemichannel open, EC activation, and atherosclerosis, which were blocked by TAT-GAP19, a Cx43 hemichannel inhibitory peptide. Mass spectrometry studies identified that Filamin B fueled the translocation of Cx43 to lipid rafts for further hemichannel open. Finally, lenti-mediated overexpression of the Cx43S255 mutant into glutamate to mimic phosphorylation blunted disturbed flow-induced EC activation, thereby inhibiting the atherogenesis in both ApoE-/- and Mst1 iECKOApoE-/- mice. CONCLUSIONS: Our study reveals that inhibition of the MST1-Cx43 axis is an essential driver of oscillatory shear stress-induced endothelial dysfunction and atherosclerosis, which provides a new therapeutic target for the treatment of atherosclerosis.

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

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 α5ß1 to traffic in response to OSS. Interference by siRNA of AnxA2 in ECs greatly decreased OSS-induced integrin α5ß1 translocation to lipid rafts, EC activation, and monocyte adhesion. Pharmacological and genetic inhibition of PTP1B (protein tyrosine phosphatase 1B) blunted OSS-induced integrin α5ß1 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 ß1. Importantly, ectopic lentiviral overexpression of an ANXA2Y24F mutant increased and shRNA against Ptp1B decreased integrin α5ß1 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 α5ß1, thereby identifying a class of potential therapeutic targets for atherosclerosis. Graphic Abstract: An graphic abstract is available for this article.

Yes-Associated Protein Promotes Angiogenesis via Signal Transducer and Activator of Transcription 3 in Endothelial Cells.

RATIONALE: Angiogenesis is a complex process regulating endothelial cell (EC) functions. Emerging lines of evidence support that YAP (Yes-associated protein) plays an important role in regulating the angiogenic activity of ECs. OBJECTIVE: The objective of this study was to specify the effect of EC YAP on angiogenesis and its underlying mechanisms. METHOD AND RESULTS: In ECs, vascular endothelial growth factor reduced YAP phosphorylation time and dose dependently and increased its nuclear accumulation. Using Tie2Cre-mediated YAP transgenic mice, we found that YAP promoted angiogenesis in the postnatal retina and tumor tissues. Mass spectrometry revealed signal transducer and activator of transcription 3 (STAT3) as a potential binding partner of YAP in ECs. Western blot and immunoprecipitation assays indicated that binding with YAP prolonged interleukin 6-induced STAT3 nuclear accumulation by blocking chromosomal maintenance 1-mediated STAT3 nuclear export without affecting its phosphorylation. Moreover, angiopoietin-2 expression induced by STAT3 was enhanced by YAP overexpression in ECs. Finally, a selective STAT3 inhibitor or angiopoietin-2 blockage partly attenuated retinal angiogenesis in Tie2Cre-mediated YAP transgenic mice. CONCLUSIONS: YAP binding sustained STAT3 in the nucleus to enhance the latter's transcriptional activity and promote angiogenesis via regulation of angiopoietin-2.

Characterization of the Interfacial Joule Heating Effect in the Electrochemical Advanced Oxidation Process.

The electrochemical advanced oxidation process (EAOP) has gained popularity in the field of water purification. During the EAOP, it is in the boundary layer of the anode-solution interface that organic pollutants are oxidized by hydroxyl radicals (•OH) produced from water oxidation. Applying current to an anode dissipates heat to the surroundings according to Joule's law, leading to an interfacial temperature that is much higher than that of the bulk solution, which is known as the "interfacial Joule heating" (IJH) effect. The modeling and experimental results show that the IJH effect had an inevitable consequence for the activity of •OH, rate constants, and mass transport within the boundary layer. The interfacial temperature could be increased from 25 to 70.2 °C, a value mostly doubling that of the bulk solution (33.6 °C) at the end of a 120 min electrolysis (10 mA cm-2). Correspondingly, the •OH concentration available for oxidation of organic pollutants was much lower than that calculated at a constant temperature of 25 °C probably due to H2O2 formation via •OH dimerization. The enhanced •OH diffusion resulting from strengthened molecular thermodynamic movement and decreased kinematic viscosity of the solution also drove •OH to move far from the anode surface and thus extended the maximum thickness of the boundary layer. The oxidation rate was positively correlated to the interfacial temperature, the activation energy, and the number of activated molecules, indicated by a 1.57-2.28-fold increase depending on the target organic compounds. The finding of the IJH effect prompts a re-examination of the literature based on a realistic rather than a constant temperature (e.g., 20-30 °C), the case reflected in a number of prior studies that does not exist virtually, and reconsideration of behaviors that can be attributed to the change in temperature during EAOP.

Concurrent Topological Structure and Cross-Infill Angle Optimization for Material Extrusion Polymer Additive Manufacturing with Microstructure Modeling.

This paper contributes a concurrent topological structure and cross-infill angle optimization method for material extrusion type additive manufacturing (AM). This method features in modeling the process-induced material anisotropy through microscopic geometric modeling obtained by scanning electron micrographs. Numerical homogenization is performed to evaluate the equivalent effective properties of the 100-percentage cross-infilled local microstructures, and by introducing fitting functions, the relationship between equivalent effective material properties and varying cross-infill angles is empirically constructed. Then, optimization problems involving cross-infill angles as design variables are formulated, including concurrent optimization formulation. Numerical and experimental studies are conducted to illustrate the effectiveness of the proposed method. Both the numerical and experimental results demonstrate that the structural stiffness obtained by our proposed method has evidently improved.

Evolutionary game analysis of FinTech transformation: A social co-governance pattern of peer-to-peer lending market in China.

Benign exit has become the main theme of the transformation in China's peer-to-peer (P2P) lending industry. To protect the interests of investors in the benign exit process, this paper proposes a social co-governance pattern using a tripartite evolutionary game model to capture the behavior strategies of P2P lending platforms, investors, and financial regulators. The results demonstrate that there are four evolutionary stable strategies for the game model, among which the positive disposal of P2P lending platforms, the participation of the investors, and the co-governance policy of financial regulators is the optimal strategy in the benign exit process. The results also show that the initial proportion of P2P lending platforms, investors, and financial regulators would significantly affect the convergence speed of the evolutionary stable strategy. The proposed social co-governance pattern would effectively safeguard the interests of investors if incentive, penalty, and reputation mechanisms are well-designed. This paper provides in-depth implications for protecting investors' interests in the transformation of the P2P lending industry and enhancing the sustainable development of the FinTech industry.

Coal-Fired Boiler Flue Gas Desulfurization System Based on Slurry Waste Heat Recovery in Severe Cold Areas.

To reduce operating costs on the basis of ensuring the desulfurization efficiency in a wet flue gas desulfurization system, a theoretical model was put forward, and a calculation method was set up. Correlations between reaction zone height, flue gas inlet temperature, slurry inlet temperature, gas-liquid ratio and desulfurization efficiency were found. Based on the heat and mass transfer model of the spray tower, the integrated system of desulfurization tower and open slurry pool and the flue gas desulfurization-waste heat recovery system were established. Additionally, the effect of outdoor wind speed, heat dissipation area and ambient temperature on the slurry equilibrium temperature in the integrated system were analyzed. The results show the slurry equilibrium temperature of the desulfurization system is negatively correlated with outdoor wind speed and heat dissipation area, and positively related to ambient temperature. The slurry temperature is the main factor that affects the performance of the wet flue gas desulfurization system. Finally, based on the Harbin heating group Hua Hui hotspot energy-saving reconstruction project, a case analysis was conducted, which proves the flue gas desulfurization-waste heat recovery system is profitable, energy saving and a suitable investment project.

Cartilage oligomeric matrix protein fine-tunes disturbed flow-induced endothelial activation and atherogenesis.

Disturbed flow leads to increased inflammatory responses of endothelial cells (ECs) prone to atherogenic state. Currently, little is known about the physiological mechanisms protecting vasculature against disturbed flow-activated ECs leading to atherosclerosis. Understanding the protective mediators involved in EC activation could provide novel therapeutic strategies for atherosclerosis. The extracellular matrix microenvironment profoundly regulates cellular homeostasis. A non-EC resident ECM protein, cartilage oligomeric matrix protein (COMP), has diverse protective roles in the cardiovascular system. To determine whether COMP could protect against disturbed flow-activated EC and atherosclerosis, we compared oscillatory shear stress (OSS) induced EC activation coated with various ECM proteins. Purified COMP inhibited EC activation caused by OSS. EC activation was upregulated in the aortic arch where the flow is disturbed in COMP-/- mice as compared with wild-type mice under physiological conditions or pathologically in partially ligated mouse carotid arteries. Mechanistically, co-immunoprecipitation, mammalian two-hybrid and FRET assay results suggest that COMP bound directly to integrin α5 via its C-terminus. We next synthesized a COMP-derived peptidomimetics (CCPep24) mimicking a specific COMP-integrin α5 interaction and found that CCPep24 protected against EC activation and atherogenesis in vivo. This study extends our current understanding of how ECM and flow coordinately fine-tune EC homeostasis and reveals the potential therapeutic effect of COMP or COMP-derived peptidomimetics on blocking aberrant integrin α5 activation, inflammatory EC activation and atherosclerosis pathogenesis.

Harmine alleviates atherogenesis by inhibiting disturbed flow-mediated endothelial activation via protein tyrosine phosphatase PTPN14 and YAP.

BACKGROUND AND PURPOSE: Disturbed flow induces endothelial dysfunction and contributes to uneven distribution of atherosclerotic plaque. Emerging evidence suggests that harmine, a natural constituent of extracts of Peganum harmala, has potent beneficial activities. Here, we investigated if harmine has an atheroprotective role under disturbed flow and the underlying mechanism. EXPERIMENTAL APPROACH: Mice of ApoE-/- , LDLR-/- , and endothelial cell (EC)-specific overexpression of yes-associated protein (YAP) in ApoE-/- background were fed with a Western diet and given harmine for 4 weeks. Atherosclerotic lesion size, cellular composition, and expression of inflammatory genes in the aortic roots were assessed. HUVECs were treated with oscillatory shear stress (OSS) and harmine and also used for proteomic analysis. KEY RESULTS: Harmine retarded atherogenesis in both ApoE-/- and LDLR-/- mice by inhibiting the endothelial inflammatory response. Mechanistically, harmine blocked OSS-induced YAP nuclear translocation and EC activation by reducing phosphorylation of YAP at Y357. Overexpression of endothelial YAP blunted the beneficial effects of harmine in mice. Proteomic study revealed that protein tyrosine phosphatase non-receptor type 14 (PTPN14) could bind to YAP. Moreover, harmine increased PTPN14 expression by stabilizing its protein level and inhibiting its degradation in proteasomes. PTPN14 knockdown blocked the effects of harmine on YAPY357 and EC activation. Finally, overexpression of PTPN14 mimicked the effects of harmine and ameliorated atherosclerosis, and knockdown of PTPN14 blunted the atheroprotective effects of harmine and accelerated atherosclerosis, in a partial ligation mouse model. CONCLUSION AND IMPLICATIONS: Harmine alleviated OSS-induced EC activation via a PTPN14/YAPY357 pathway and had a potent atheroprotective role.

c-Abl regulates YAPY357 phosphorylation to activate endothelial atherogenic responses to disturbed flow.

Local flow patterns determine the uneven distribution of atherosclerotic lesions. This research aims to elucidate the mechanism of regulation of nuclear translocation of Yes-associated protein (YAP) under oscillatory shear stress (OSS) in the atheroprone phenotype of endothelial cells (ECs). We report here that OSS led to tyrosine phosphorylation and strong, continuous nuclear translocation of YAP in ECs that is dependent on integrin α5ß1 activation. YAP overexpression in ECs blunted the anti-atheroprone effect of an integrin α5ß1-blocking peptide (ATN161) in Apoe-/- mice. Activation of integrin α5ß1 induced tyrosine, but not serine, phosphorylation of YAP in ECs. Blockage of integrin α5ß1 with ATN161 abolished the phosphorylation of YAP at Y357 induced by OSS. Mechanistic studies showed that c-Abl inhibitor attenuated the integrin α5ß1-induced YAP tyrosine phosphorylation. Furthermore, the phosphorylation of c-Abl and YAPY357 was significantly increased in ECs in atherosclerotic vessels of mice and in human plaques versus normal vessels. Finally, bosutinib, a tyrosine kinase inhibitor, markedly reduced the level of YAPY357 and the development of atherosclerosis in Apoe-/- mice. The c-Abl/YAPY357 pathway serves as a mechanism for the activation of integrin α5ß1 and the atherogenic phenotype of ECs in response to OSS, and provides a potential therapeutic strategy for atherogenesis.

[Isolation, cultivation and identification of neural stem cell from human embryonic CNS].

This is a study on the cultivation condition in vitro and differentiation of neural stem cells from human embryonic brain in order to find a way to get purified multipotential neural stem cells. The single cells was derived from the three-month embryonic brain digested with trypsin, some cells was frozen, the other cells were expanded with EGF and bFGF, the single-cell-clone was obtained by the way of limited dilution, and the serum was used to induce the cells differentiation. The cells were detected with the method of immunohistochemistry. The results showed that a lot of neurospheres could be seen in the presence of mitogens (both EGF and bFGF) and serum could induce neural stem cells to differentiate into neurons, astrocytes, and oligodendrocytes. These indicate that the survival and proliferation of neural stem cells rely on the cooperation of EGF and bFGF. The neural stem cells can also be harvested from the frozen cells.