Abstract：
Hyperlipidemia with high blood levels of free fatty acids (FFA) is the leading cause of non-alcoholic steatohepatitis. CCN1 is a secreted matricellular protein that drives various cellular functions, including proliferation, migration, and differentiation. However, its role in mediating FFA-induced pro-inflammatory cell death and its underlying molecular mechanisms have not been characterized. In this study, we demonstrated that CCN1 was upregulated in the livers of obese mice. The increase in FFA-induced CCN1 was evaluated in vitro by treating hepatocytes with a combination of oleic acid and palmitic acid (2:1). Gene silencing using specific small interfering RNAs (siRNA) revealed that CCN1 participated in FFA-induced intracellular lipid accumulation, caspase-1 activation, and hepatocyte pyroptosis. Next, we identified integrin α5β1 as a potential receptor of CCN1. Co-immunoprecipitation demonstrated that the binding between CCN1 and integrin α5β1 increased in hepatocytes upon FFA stimulation in the livers of obese mice. Similarly, the protein levels of integrin α5 and β1 were increased in vitro and in vivo. Experiments with specific siRNAs confirmed that integrin α5β1 played a part in FFA-induced intracellular lipid accumulation, NLRP3 inflammasome activation, and pyroptosis in hepatocytes. In conclusion, these results provide novel evidence that the CCN1/integrin α5β1 is a novel mediator that drives hepatic lipotoxicity via NLRP3-dependent pyroptosis.
摘要：
高血游离脂肪酸(FFA)的高脂血症是非酒精性脂肪性肝炎的主要原因。CCN1是一种分泌的基质细胞蛋白，驱动各种细胞功能，包括扩散，迁移,和差异化。然而,其在介导FFA诱导的促炎细胞死亡中的作用及其潜在的分子机制尚未明确.在这项研究中,我们证明肥胖小鼠肝脏中CCN1上调.通过用油酸和棕榈酸(2:1)的组合处理肝细胞在体外评估FFA诱导的CCN1的增加。使用特定的小干扰RNA（siRNA）的基因沉默表明，CCN1参与FFA诱导的细胞内脂质积累，caspase-1激活，和肝细胞焦亡。接下来,我们确定整合素α5β1为CCN1的潜在受体。免疫共沉淀表明，在肥胖小鼠肝脏中，FFA刺激后，肝细胞中CCN1与整联蛋白α5β1之间的结合增加。同样，整合素α5和β1的蛋白质水平在体外和体内均升高。特定siRNA的实验证实整合素α5β1在FFA诱导的细胞内脂质积累中起作用，NLRP3炎性体激活，和肝细胞的焦亡。总之,这些结果提供了新的证据,即CCN1/整合素α5β1是通过NLRP3依赖性焦亡驱动肝脂毒性的新型介体.
