CTRP9 prevents atherosclerosis progression through changing autophagic status of macrophages by activating USP22 mediated-de- ubiquitination on Sirt1

Abstract

Abstract Background: Atherosclerosis (AS) is commonly regarded as a key driver accounted for the leading causes of morbidity and mortality among cardiovascular and cerebrovascular diseases. A growing body evidence indicates that autophagy in macrophages involved in AS might be a potential therapeutic target. C1q/TNF-related protein 9 (CTRP9) has been proved to delay the progression of cardiovascular diseases. However, the relations among CTRP9 and Sirt1 either with its effects on macrophages autophagy has not been fully explored. Methods: Macrophages were differentiated from the mononuclear cells collected from the peripheral blood samples of healthy donors. The in vitro AS model were constructed by ox-LDL treatment. Cell viability was determined by CCK-8 assay. Immunofluorescence assay of LC3 was implemented for evaluating autophagy activity. Oil Red O staining was performed for lipid accumulation detection. ELISA, cholesterol concentration assay and cholesterol efflux analysis was conducted using commercial kit. Cycloheximide assay was implemented for revealing protein stability. RT-qPCR was used for mRNA expression detection, and western blotting was performed for protein level monitoring. Results: CTRP9 attenuated impaired cell viability, autophagy inhibition and increased lipid accumulation induced by ox-LDL. Moreover, CTRP9 maintained Sirt1 protein level through enhancing its stability by de-ubiquitination, which was mediated by upregulated USP22 level. CRTP9 exerted its protective role in promoting autophagy and reducing lipid accumulation through USP22/Sirt1 axis. Conclusion: Collectively, CTRP9 alleviates lipid accumulation and facilitated the macrophages autophagy through upregulating USP22 level and maintaining Sirt1 protein expression, thereby exerting a protective role in AS progression.