Department of Hepatobiliary Surgery, the Fifth Affiliated Hospital, Southern Medical University, Guangzhou, P. R. China.
Department of Hepatobiliary Surgery II, Zhujiang Hospital, Southern Medical University, Guangzhou, P. R. China.
FASEB J. 2021 Apr;35(4):e21230. doi: 10.1096/fj.202000683R.
Previous literature has indicated that cyclin-dependent kinase inhibitor 2 A (CDKN2A) is upregulated, while the Protein Inhibitor of Activated STAT1 (PIAS1) is downregulated in the liver tissues of obese mice. The current study aimed to investigate the relationship between CDKN2A and PIAS1 in the lipogenesis of fatty liver disease. In the C57BL/6J db/db mouse model and hepatocyte model of fatty liver, the expression pattern of CDKN2A, PIAS1, Protein arginine methyltransferase 1 (PRMT1) and CASP8 and FADD-like apoptosis regulator (CFLAR) was characterized by RNA quantitative and Western blot analysis. The lipogenesis-related genes (Srebp1c and Fas) in the liver tissues and cells were employed in the assessment of lipogenesis in response to gain- or loss-of-function of CDKN2A, PIAS1, PRMT1, and CFLAR, while triglyceride and fat content were evaluated in relation to fat accumulation. Western blot analysis was conducted to determine c-Jun amino-terminal kinase (JNK) phosphorylation, while the ubiquitination of CFLAR and SUMOylation of PIAS1 was examined by immunoprecipitation. PIAS1 and CFLAR were downregulated, while CDKN2A, PRMT1, and phosphorylation of JNK was elevated in the tissues and cells of the fatty liver models. Our results suggested that CDKN2A enhanced the SUMOylation of PIAS1 to reduce the expression of PIAS1. PRMT1 downregulated CFLAR by triggering its ubiquitination, while CFLAR repressed phosphorylation of JNK. The in vitro and in vivo results indicated that CDKN2A silencing prevented lipogenesis and fat accumulation by impairing the PRMT1-dependent ubiquitination of CFLAR and blocking the phosphorylation of JNK. Taken together, the central observations of our study demonstrate that targeting CDKN2A contributes to the suppression of lipogenesis and fat accumulation in fatty liver disease. The findings of our study highlight the potential of CDKN2A as a promising target against fatty liver.
先前的文献表明，肥胖小鼠的肝组织中细胞周期蛋白依赖性激酶抑制剂 2A（CDKN2A）上调，而信号转导和转录激活因子 1 的蛋白抑制剂（PIAS1）下调。本研究旨在探讨 CDKN2A 与 PIAS1 在脂肪肝脂肪生成中的关系。在 C57BL/6J db/db 肥胖小鼠模型和脂肪性肝病的肝细胞模型中，通过 RNA 定量和 Western blot 分析来描述 CDKN2A、PIAS1、精氨酸甲基转移酶 1（PRMT1）和胱天蛋白酶 8 和 FADD 样凋亡调节剂（CFLAR）的表达模式。在肝组织和细胞中，使用与脂肪生成相关的基因（Srebp1c 和 Fas）来评估 CDKN2A、PIAS1、PRMT1 和 CFLAR 的功能获得或缺失对脂肪生成的影响，同时评估甘油三酯和脂肪含量与脂肪积累的关系。通过 Western blot 分析来检测 c-Jun 氨基末端激酶（JNK）磷酸化，通过免疫沉淀检测 CFLAR 的泛素化和 PIAS1 的 SUMO 化。在脂肪肝模型的组织和细胞中，PIAS1 和 CFLAR 下调，而 CDKN2A、PRMT1 和 JNK 的磷酸化升高。我们的结果表明，CDKN2A 增强了 PIAS1 的 SUMO 化，从而降低了 PIAS1 的表达。PRMT1 通过触发 CFLAR 的泛素化来下调 CFLAR，而 CFLAR 抑制 JNK 的磷酸化。体外和体内结果表明，CDKN2A 沉默通过损害 PRMT1 依赖性 CFLAR 泛素化和阻断 JNK 磷酸化来阻止脂肪生成和脂肪积累。综上所述，我们研究的主要观察结果表明，靶向 CDKN2A 有助于抑制脂肪肝中的脂肪生成和脂肪积累。我们的研究结果强调了 CDKN2A 作为治疗脂肪肝的有前途的靶点的潜力。
