Zhou Guangxi, Hou Fei, He Heng, Xue Yuan, Wang Yibo, Chen Xueying, Zhu Fengqin
Department of Gastroenterology, Affiliated Hospital of Jining Medical University, Jining Medical University, 272000 Jining, Shandong, China.
Shandong University of Traditional Chinese Medicine, 250355 Jinan, Shandong, China.
Front Biosci (Landmark Ed). 2022 Dec 20;27(12):324. doi: 10.31083/j.fbl2712324.
Cholangiocytes are primary targets in chronic cholestatic liver diseases. Myocyte enhancer factor 2A (MEF2A) is a transcription factor with a crucial role in some fibrogenic diseases. However, whether it contributes to cholestatic liver fibrosis is still obscure.
A bile duct-ligated (BDL) mouse model was established to detect MEF2A expression during cholestatic liver fibrosis. In addition, human intrahepatic biliary epithelial cells (HIBECs) were transfected with lentivirus-expressing shMEF2A (LV-shMEF2A) to regulate the expression of MEF2A . Biomarkers of epithelial to mesenchymal transition (EMT), senescence, and fibrogenesis were evaluated using various assays: Quantitative real-time polymerase chain reaction (qRT-PCR), western blotting, senescence-associated β-galactosidase (SA-β-gal), and immunofluorescence. Furthermore, MEF2A expression and cytoplasm translocation induced by transforming growth factor β1 (TGF-β1) in HIBECs were determined by qRT-PCR, western blotting, and immunofluorescence. The expression of TGF-β1-induced MEF2A, EMT, senescence, and fibrosis markers inhibited by p38 MAPK signaling were evaluated by western blotting. Finally, the peripheral blood from primary biliary cholangitis (PBC) patients and healthy controls (HCs) was collected to analyze expression of MEF2A using Enzyme-linked immunosorbent assay (ELISA).
We found that MEF2A expression increased in liver tissues of BDL mice, and positively related to the extent of fibrosis. Silencing MEF2A in HIBECs restrained TGF-β1-induced EMT, senescence, and fibrotic reaction. Moreover, TGF-β1 enhanced the expression of MEF2A and induced its cytoplasm translocation in a concentration- and time-dependent manner, partially through interacting with p38 MAPK. The expression of MEF2A was also higher in the serum of PBC patients than in HCs, and positively correlated with fibrosis degree.
Our study demonstrates that MEF2A is a central mediator linking TGF-β1-induced EMT and senescence in HIBECs. We propose it as a novel biomarker of fibrogenesis in cholestatic liver fibrosis. We also suggest inhibiting MEF2A as a potential strategy in treating cholestatic liver fibrosis.
胆管细胞是慢性胆汁淤积性肝病的主要靶点。肌细胞增强因子2A（MEF2A）是一种转录因子，在某些纤维化疾病中起关键作用。然而，它是否参与胆汁淤积性肝纤维化仍不清楚。
建立胆管结扎（BDL）小鼠模型以检测胆汁淤积性肝纤维化过程中MEF2A的表达。此外，用表达慢病毒短发夹RNA（LV-shMEF2A）转染人肝内胆管上皮细胞（HIBECs）来调节MEF2A的表达。使用多种检测方法评估上皮-间质转化（EMT）、衰老和纤维化的生物标志物：定量实时聚合酶链反应（qRT-PCR）、蛋白质免疫印迹法、衰老相关β-半乳糖苷酶（SA-β-gal）和免疫荧光。此外，通过qRT-PCR、蛋白质免疫印迹法和免疫荧光检测HIBECs中转化生长因子β1（TGF-β1）诱导的MEF2A表达和细胞质转位。通过蛋白质免疫印迹法评估p38丝裂原活化蛋白激酶（MAPK）信号通路抑制TGF-β1诱导的MEF2A、EMT、衰老和纤维化标志物的表达。最后，收集原发性胆汁性胆管炎（PBC）患者和健康对照（HCs）的外周血，采用酶联免疫吸附测定（ELISA）分析MEF2A的表达。
我们发现BDL小鼠肝组织中MEF2A表达增加，且与纤维化程度呈正相关。在HIBECs中沉默MEF2A可抑制TGF-β1诱导的EMT、衰老和纤维化反应。此外，TGF-β1以浓度和时间依赖性方式增强MEF2A的表达并诱导其细胞质转位，部分是通过与p38 MAPK相互作用实现的。PBC患者血清中MEF2A的表达也高于HCs，且与纤维化程度呈正相关。
我们的研究表明，MEF2A是连接HIBECs中TGF-β1诱导的EMT和衰老的核心介质。我们提出将其作为胆汁淤积性肝纤维化中纤维化形成的一种新型生物标志物。我们还建议抑制MEF2A作为治疗胆汁淤积性肝纤维化的一种潜在策略。
