周施施, 张印良, 常永生*
非酒精性脂肪性肝病(nonalcoholic fatty liver disease, NAFLD)的发生和发展与脂肪酸的摄取密切相关。本研究旨在探索Krüppel样转录因子9 (Krüppel-like factor 9, KLF9)对脂肪酸转位酶CD36、肝细胞的脂代谢以及非酒精性脂肪肝的发生和发展所产生的影响。采用高脂饮食构建的高脂模型C57BL/6J小鼠和db/db糖尿病小鼠，检测其肝脏内Klf9和Cd36基因和蛋白表达水平的变化。分离C57BL/6J小鼠原代肝细胞进行体外培养，分别给予Ad-GFP、Ad-Klf9、Ad-shCtrl或Ad-shKlf9处理，然后利用油酸和棕榈酸进行24 h的诱导；同时构建肝脏特异性Klf9基因敲除小鼠，采用Western blot检测KLF9蛋白表达水平的变化，real-time PCR检测Klf9和Cd36 mRNA表达水平的变化，试剂盒测定甘油三酯含量的变化，油红O染色检测脂质含量的变化。结果显示：(1)与对照组相比，高脂饮食诱导的肥胖小鼠或db/db糖尿病小鼠肝脏Klf9的表达显著增加；(2)在小鼠原代肝脏细胞中过量表达Klf9会增加Cd36表达水平，导致细胞脂肪含量增加；(3)相反，在小鼠原代肝脏细胞中敲低Klf9的表达则降低Cd36表达水平，从而减少肝细胞脂肪含量；(4)小鼠肝脏Klf9敲除能降低肝脏Cd36表达，改善高脂饮食诱导的脂肪肝表型。上述结果表明，肝脏KLF9通过促进CD36的表达影响肝脏的脂代谢。
KLF9 regulates hepatic lipid metabolism via inducing CD36 expression
ZHOU Shi-Shi, ZHANG Yin-Liang, CHANG Yong-Sheng*
Department of Physiology and Pathophysiology, Basic Medical College, Tianjin Medical University, Tianjin 300070, China
The development of nonalcoholic fatty liver disease (NAFLD) is closely related to the fatty acid (FA) uptake. This study aimed to investigate the effect of Krüppel-like factor 9 (KLF9) on CD36 (typical fatty acid translocase), hepatocellular lipid metabolism as well as the development and progression of nonalcoholic fatty liver. High-fat diet-induced obese C57BL/6J mice and db/db mice were used to test the expression levels of Klf9 and Cd36 in the livers. The primary hepatocytes were isolated from C57BL/6J mice, treated with Ad-GFP, Ad-Klf9, Ad-shCtrl or Ad-shKlf9, and then incubated with oleic acid and palmitic acid for 24 h. Liver-specific knockout of Klf9 mice were established. The protein levels and relative mRNA levels were examined by Western blot and real-time PCR, respectively. Triglyceride content was determined by using an assay kit. Lipid content was determined by Oil Red O staining. The results showed that: (1) Klf9 expression levels were increased in the livers of high-fat diet-induced obese mice and db/db mice, compared to their respective control mice. (2) Adenovirus-mediated overexpression of Klf9 in primary hepatocytes increased Cd36 expression and cellular triglyceride contents. (3) In contrast, adenovirus-mediated knockdown of Klf9 expression in primary hepatocytes by Ad-shKlf9 decreased Cd36 expression and cellular triglyceride contents. (4) Finally, Klf9 deficiency decreased liver Cd36 expression and alleviated fatty liver phenotype of high-fat diet-induced obese mice. These results suggest that KLF9 can regulate hepatic lipid metabolism and development of NAFLD by promoting the expression of CD36.
通讯作者：常永生 E-mail: email@example.com
周施施, 张印良, 常永生. KLF9通过上调CD36调节肝脏脂代谢[J]. 生理学报 2021; 73 (5): 772-780.
ZHOU Shi-Shi, ZHANG Yin-Liang, CHANG Yong-Sheng. KLF9 regulates hepatic lipid metabolism via inducing CD36 expression. Acta Physiol Sin 2021; 73 (5): 772-780 (in Chinese with English abstract).