Chen Yu-Chi, Chen Rong-Jane, Peng Szu-Yuan, Yu Winston C Y, Chang Vincent Hung-Shu
Department of Biotechnology, National Kaohsiung Normal University, Kaohsiung, Taiwan.
Department of Food Safety/Hygiene and Risk Management, College of Medicine, National Cheng Kung University, Tainan, Taiwan.
Front Mol Biosci. 2021 Nov 12;8:751938. doi: 10.3389/fmolb.2021.751938. eCollection 2021.
Krüppel-like factor 10 (KLF10) is a phospho-regulated transcriptional factor involved in many biological processes including lipogenesis; however, the transcriptional regulation on lipogenesis by KLF10 remains largely unclear. Lipogenesis is important in the development of nonalcoholic fatty liver disease (NAFLD) which was known regulated mainly by AMP-activated protein kinase (AMPK) and sterol regulatory element-binding protein (SREBP-1C). Interesting, our previous study using phosphorylated site prediction suggested a regulation of AMPK on KLF10. Therefore, we aimed to study the protein-protein interactions of AMPK on the regulation of KLF10, and to delineate the mechanisms of phosphorylated KLF10 in the regulation of NAFLD through SREBP-1C. We performed and assays that identified AMPK phosphorylates KLF10 at Thr189 and subsequently modulates the steady state level of KLF10. Meanwhile, a chromatin immunoprecipitation-chip assay revealed the novel target genes and signaling cascades of corresponding to phosphorylated KLF10. SREBP-1C was identified as a target gene suppressed by phosphorylated KLF10 through promoter binding. We further performed high-fat-diet-induced NAFLD models using hepatic-specific KLF10 knockout mice and wild-type mice and revealed that KLF10 knockout markedly led to more severe NAFLD than that in wild-type mice. Taken together, our findings revealed for the first time that AMPK activates and stabilizes the KLF10 protein phosphorylation at Thr189, thereby repressing the expression of SREBP-1C and subsequent lipogenesis pathways along with metabolic disorders. We suggested that the targeted manipulation of liver metabolism, particularly through increased KLF10 expression, is a potential alternative solution for treating NAFLD.
Krüppel样因子10（KLF10）是一种磷酸化调节的转录因子，参与包括脂肪生成在内的许多生物学过程；然而，KLF10对脂肪生成的转录调控仍不清楚。脂肪生成在非酒精性脂肪性肝病（NAFLD）的发展中很重要，已知其主要受AMP激活的蛋白激酶（AMPK）和固醇调节元件结合蛋白（SREBP-1C）调控。有趣的是，我们之前使用磷酸化位点预测的研究表明AMPK对KLF10有调控作用。因此，我们旨在研究AMPK在KLF10调控中的蛋白质-蛋白质相互作用，并阐明磷酸化的KLF10通过SREBP-1C调控NAFLD的机制。我们进行了实验和分析，确定AMPK在Thr189位点磷酸化KLF10，随后调节KLF10的稳态水平。同时，染色质免疫沉淀芯片分析揭示了与磷酸化KLF10相对应的新靶基因和信号级联反应。通过启动子结合，SREBP-1C被确定为受磷酸化KLF10抑制的靶基因。我们进一步使用肝脏特异性KLF10基因敲除小鼠和野生型小鼠构建了高脂饮食诱导的NAFLD模型，发现KLF10基因敲除显著导致比野生型小鼠更严重的NAFLD。综上所述，我们的研究首次揭示，AMPK激活并稳定KLF10蛋白在ThrI89位点的磷酸化，从而抑制SREBP-1C的表达以及随后的脂肪生成途径和代谢紊乱。我们认为，针对肝脏代谢的靶向操作，特别是通过增加KLF10的表达，是治疗NAFLD的一种潜在替代方案。
