LAL对奶牛脂肪细胞脂合成及脂解的调节作用

Effects of LAL on lipid synthesis and lipolysis in adipocytes of dairy cows

检测健康奶牛及酮病奶牛脂肪组织中调节脂合成相关分子乙酰CoA羧化酶-1(ACC1)、磷酸化转录调节因子-α(CEBPα)、二酰基甘油酰基转移酶2(DGAT2)、固醇调节元件结合蛋白1(SREBP1)和过氧化物酶体增殖物激活受体-γ(PPARγ)和脂解相关分子脂滴包被蛋白-1(PLIN1)、甘油三酯脂酶(ATGL)、激素敏感性脂肪酶(HSL)、p-HSL的蛋白表达以及目的蛋白溶酶体酸性脂肪酶(lysosomal acid lipase,LAL)的表达;研究体外培养原代牛脂肪细胞过表达LAL,并添加异丙肾上腺素(ISO)构建脂肪细胞脂解模型,采用Western blot检测脂肪细胞中脂合成及脂解相关蛋白表达的情况。结果显示,与健康奶牛相比,酮病奶牛脂肪组织中的LAL表达量显著低于健康奶牛(P<0.01)。临床型酮病奶牛脂肪组织中脂合成相关蛋白ACC1、CEBPα、DGAT2、SREBP1、PPARγ的蛋白表达水平显著降低,而脂解相关蛋白PLIN1、ATGL、p-HSL的蛋白表达及磷酸化水平显著升高,结果表明酮病奶牛脂肪组织脂质合成作用被抑制,脂解作用增强。体外试验结果显示,ISO可下调脂合成相关分子的蛋白表达水平,也会上调脂解相关分子的蛋白表达及磷酸化水平。过表达LAL的奶牛脂肪细胞基础脂合成和ISO诱导下的脂合成蛋白的含量显著升高,而基础脂解和ISO诱导的脂解蛋白含量显著降低。体外试验结果表明,LAL在奶牛脂肪细胞中能抑制脂肪细胞的脂分解,并促进脂肪细胞的脂合成。

In order to investigate the effects of LAL on the lipolysis and lipid synthesis of dairy adipocytes,the protein expressions of lipid synthesis-related molecules,acetyl-CoA carboxylase-1(ACC1),phosphorylated transcription factor-α(CEBPα),diacylglyceryl acyltransferase 2(DGAT2),sterol regulatory element binding protein 1(SREBP1),and peroxisome proliferator-activated receptor-γ(PPARγ),and lipolysis-related molecules,lipid droplet coated protein-1(PLIN1),triglyceride lipase(ATGL),hormone-sensitive lipase(HSL),p-HSL,and the target protein lysosomal acid lipase(LAL),were detected in adipose tissues of healthy dairy cows and ketosis cows.The lipid synthesis and lipolysis-related protein expressions in adipocytes were detected by Western blot technology.The primary bovine adipocytes were cultured in vitro with overexpressed LAL,and the lipolysis model of adipocytes was constructed by adding isoproterenol(ISO).The results showed that the expression of LAL in adipose tissue of ketosis cows was significantly lower than that of healthy cows(P<0.01).Compared with healthy cows,the protein expression levels of lipid synthesis-related proteins ACC1,CEBPα,DGAT2,SREBP1 and PPARγin adipose tissue of clinical ketosis cows were significantly decreased,while the protein expression and phosphorylation levels of lipolysis-related proteins,PLIN1,ATGL,and p-HSL were significantly increased.The above results confirmed that the lipid synthesis of adipose tissue of ketosis cows was inhibited,and the lipolysis was enhanced.In vitro results showed that ISO could downregulate the protein expression levels of lipid synthesis related molecules,and upregulate the protein expression and phosphorylation levels of lipid lysis related molecules in bovine adipocytes.The content of basal lipid synthesis and ISO-induced lipid synthesis proteins in bovine adipocytes of LAL overexpression group was significantly increased,while the content of basal lipid lysis and ISO-induced lipid lysis proteins was significantly decreased.In conclusion,in vivo and in vitro studies have shown that LAL can inhibit the lipid lysis of bovine adipocytes and promote the lipid synthesis of bovine adipocytes.