Hepatocyte-specific knockout of YAP protects against atherosclerosis via inhibition of ANGPTL3 in mice

Background and AimsLipid-lowering therapy is one important cornerstone for atherosclerotic cardiovascular disease treatment (ASCVD). Although some lipid-lowering drugs (e.g statins, cholesterol absorption inhibitors and PCSK9-inhibitors) displayed good lipid profiles and positive effects on ASCVD, lipid-lowering clinical treatment for homozygous familial hypercholesterolemia patients still faces challenges attributing to lack of therapeutic targets. Given that Yes-associated protein (YAP) may be involved in lipid metabolism in the liver, we assessed function of hepatic YAP in dyslipidemia and atherosclerosis.MethodsHyperlipidemia models were built in mice injected by adeno-associated virus 8 (AAV8)-D377Y-mPCSK9 degrading LDLR to lead to its deletion or global apoE knockout background mice by being given a high cholesterol diet for 12 weeks. We detected expression of hepatic YAP in global apoE knockout mice fed by the high cholesterol diet for 12 weeks. An AAV9-delivered CRISPR/Cas9-mediated YAP-/- system (AAV9-saCas9/sgYAP) was used to induce global YAP deletion in global apoE knockout mice to investigate role of whole-body YAP in hyperlipidemia and atherosclerosis. Furthermore, we created hepatocyte-specific YAP and global apoE double knockout mice to further determine role of hepatocellular YAP in hyperlipidemia and atherosclerosis. Elucidation of its molecular mechanism was performed in mice injected by AAV8-D377Y-mPCSK9 or hepatocyte-specific YAP and global apoE double knockout mice. Finally, we use global apoE knockout or global LDLR knockout mice to observe the therapeutic efficacy for hyperlipidemia and atherosclerosis of AAV8-Alb-shYAP.ResultsYAP expression was increased in the liver of the high cholesterol diet-fed apoE-/- mice. Global YAP deletion mediated by AAV9-saCas9/sgYAP reduced blood lipid level and ameliorated atherosclerosis-related phenotypes in global apoE knockout mice receiving the high cholesterol diet feed. Further investigation indicated that hepatocyte-specific YAP and global apoE double knockout mice exhibited lighter hyperlipidemia and atherosclerosis-related phenotypes that those of floxed-YAP and global apoE knockout mice after feeding the high cholesterol diet. Conversely, hepatocyte-specific overexpression of YAP(5S) deteriorated hyperlipidemia and atherosclerosis in global apoE knockout mice fed by the high cholesterol diet. Mechanistically, lipid-lowering effect of hepatocyte-specific deficiency of YAP is independent of LDLR pathway. Most importantly, hepatocyte-specific overexpression of ANGPTL3, as a hepatokines positively regulating lipid metabolism in the LDLR-independent manner, aggravated hyperlipidemia and atherosclerosis in hepatocyte-specific YAP and global apoE double knockout mice, indicating that ANGPTL3 is responsible for the function of YAP in hyperlipidemia. Notably, AAV8-Alb-shYAP has benefit of lipid-lowering in global apoE knockout or global LDLR knockout mice.ConclusionTaken together, our findings revealed a novel regulatory role for the YAP-ANGPTL3 signaling axis in lipid metabolism independent of LDLR pathway. In other words, inhibition of hepatocellular YAP may be an effective lipid-lowering strategy of homozygous familial hypercholesterolemia patients.