Lin Yuli, Hou Wulei, Ge Mengxiao, Wu Zhihao, Huang Linlin, Liu Haoye, Zhang Wenli, Deng Xiyu, Wang Lanxin, Guan Ming, Song Chunhua, Wang Zuoyun, Yang Dongqin
Department of Laboratory Medicine and Central Laboratory of Huashan Hospital, Fudan University, Shanghai 200040, China.
Department of Immunology and Department of Anatomy, Histoembryology, School of Basic Medical Sciences, Shanghai Medical College, Fudan University, Shanghai 200032, China.
Clin Mol Hepatol. 2025 Aug 8. doi: 10.3350/cmh.2024.1041.
Excessive lipid accumulation in hepatocytes is a critical cause of metabolic dysfunction-associated steatotic liver disease (MASLD) progression. Ankyrin repeat and SOCS box protein 3 (ASB3) is an E3 ubiquitin ligase that mediates diverse disease processes; however, the direct substrates of ASB3 in lipid metabolism and its role in MASLD remain unexplored.
We generated ASB3 knockout mice fed a high-fat diet (HFD) to induce MASLD. Oxygen consumption and fatty acid oxidation (FAO) were used to assess lipid metabolism. LC‒MS/MS and IP were used to verify the ASB3 target protein. Correlation analysis was conducted on the cohort of MASLD patients versus the control group.
Loss of the ASB3 E3 ubiquitin ligase in hepatocytes strengthens mitochondrial FAO, thereby influencing energy consumption to decrease triglyceride storage and lipid accumulation. Quantitative lysine ubiquitination proteomics revealed that ASB3 directly mediated the ubiquitin levels at two sites (K180 and K639) in carnitine palmitoyl transferase 1A (CPT1A), a rate-limiting enzyme of FAO, to induce CPT1A degradation. Moreover, both constitutive and hepatocyte-specific ASB3 knockout enhance FAO and delay lipid accumulation, liver steatosis, and MASLD progression in a CPT1A-dependent manner. Hepatic ASB3 deficiency also delays fibrosis in MASLD. Analysis of public databases and liver tissue samples from MASLD patients revealed that ASB3 was highly expressed in MASLD patients and was negatively correlated with CPT1A.
Our study reveals the key roles of ASB3 in the development of MASLD and suggests a novel therapeutic potential for MASLD.
肝细胞中过量的脂质积累是代谢功能障碍相关脂肪性肝病（MASLD）进展的关键原因。锚蛋白重复序列和SOCS盒蛋白3（ASB3）是一种E3泛素连接酶，介导多种疾病过程；然而，ASB3在脂质代谢中的直接底物及其在MASLD中的作用仍未被探索。
我们构建了喂食高脂饮食（HFD）以诱导MASLD的ASB3基因敲除小鼠。通过耗氧量和脂肪酸氧化（FAO）来评估脂质代谢。采用液相色谱-串联质谱（LC-MS/MS）和免疫沉淀（IP）来验证ASB3的靶蛋白。对MASLD患者队列与对照组进行相关性分析。
肝细胞中ASB3 E3泛素连接酶的缺失增强了线粒体FAO，从而影响能量消耗，减少甘油三酯储存和脂质积累。定量赖氨酸泛素化蛋白质组学显示，ASB3直接介导脂肪酸氧化限速酶肉碱棕榈酰转移酶1A（CPT1A）两个位点（K180和K639）的泛素水平，以诱导CPT1A降解。此外，组成型和肝细胞特异性ASB3基因敲除均以CPT1A依赖的方式增强FAO并延缓脂质积累、肝脏脂肪变性和MASLD进展。肝脏ASB3缺乏也延缓了MASLD中的纤维化。对MASLD患者的公共数据库和肝组织样本分析显示，ASB3在MASLD患者中高表达，且与CPT1A呈负相关。
我们的研究揭示了ASB3在MASLD发生发展中的关键作用，并提示了MASLD的一种新的治疗潜力。
