The PNPLA3 I148M Variant Modulates the Fibrogenic Phenotype of Human Hepatic Stellate Cells
The PNPLA3 I148M Variant Modulates the Fibrogenic Phenotype of Human Hepatic Stellate Cells
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DOI：
10.1002/hep.29041
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发表时间：
2017-06-01
期刊：
影响因子：
13.5
通讯作者：
Trauner, Michael
中科院分区：
文献类型：
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作者：
Bruschi, Francesca Virginia;Claudel, Thierry;Trauner, Michael
马铃薯糖样磷脂酶结构域3（PNPLA 3）的遗传多态性I148 M与肝脂肪变性及其进展为脂肪性肝炎、纤维化和癌症密切相关。肝星状细胞（HSC）是肝纤维化发展的关键参与者，但PNPLA 3及其变体I148 M在此过程中的作用知之甚少。在这里，我们分析了PNPLA 3在人HSC活化过程中的表达，从而探讨了PNPLA 3变体如何影响肝纤维化。我们发现PNPLA 3基因和蛋白的表达在活化的早期阶段增加，并且在完全活化的HSC中保持升高（P < 0.01）。PNPLA 3的敲低显著降低了促纤维化蛋白α-平滑肌肌动蛋白（P < 0.05）。原代培养的人I148 M HSC表达和释放趋化因子（C-C基序）配体5（P < 0.01）和粒细胞-巨噬细胞集落刺激因子（P < 0.001）等促炎细胞因子，促进免疫细胞迁移（P < 0.05）。原代培养的I148 M HSC中视黄醇含量降低（P < 0.001），但脂滴含量增加（P < 0.001）。与此一致，稳定过表达I148 M的LX-2细胞表现出增强的增殖和迁移，较低的视黄醇，并取消类视黄醇X受体/类视黄醇A受体的转录活性，但更多的脂滴。I148 M PNPLA 3的敲低（P < 0.001）也降低了趋化因子（C-C基序）配体5和胶原1a 1的表达（P < 0.05）。值得注意的是，I148 M细胞显示出降低的过氧化物酶体增殖物激活受体γ转录活性，并且这种作用归因于增加的c-Jun N-末端激酶，从而通过丝氨酸84磷酸化抑制过氧化物酶体增殖物激活受体γ并促进激活蛋白1转录。相反，c-Jun N-末端激酶抑制剂SP 600125和过氧化物酶体增殖物激活受体γ激动剂罗格列酮降低激活蛋白1启动子活性。结论：这些数据表明，PNPLA 3是HSC活化所需的，并且其遗传变体I148 M增强了HSC的促纤维化特征，为携带I148 M变体的患者赋予更高的肝病进展和严重程度风险提供了分子机制。
The genetic polymorphism I148M of patatin-like phospholipase domain-containing 3 (PNPLA3) is robustly associated with hepatic steatosis and its progression to steatohepatitis, fibrosis, and cancer. Hepatic stellate cells (HSCs) are key players in the development of liver fibrosis, but the role of PNPLA3 and its variant I148M in this process is poorly understood. Here we analyzed the expression of PNPLA3 during human HSC activation and thereby explored how a PNPLA3 variant impacts hepatic fibrogenesis. We show that expression of PNPLA3 gene and protein increases during the early phases of activation and remains elevated in fully activated HSCs (P < 0.01). Knockdown of PNPLA3 significantly decreases the profibrogenic protein alpha-smooth muscle actin (P < 0.05). Primary human I148M HSCs displayed significantly higher expression and release of proinflammatory cytokines, such as chemokine (C-C motif) ligand 5 (P < 0.01) and granulocyte-macrophage colony-stimulating factor (P < 0.001), thus contributing to migration of immune cells (P < 0.05). Primary I148M HSCs showed reduced retinol (P < 0.001) but higher lipid droplet content (P < 0.001). In line with this, LX-2 cells stably overexpressing I148M showed augmented proliferation and migration, lower retinol, and abolished retinoid X receptor/retinoid A receptor transcriptional activities but more lipid droplets. Knockdown of I148M PNPLA3 (P < 0.001) also reduces chemokine (C-C motif) ligand 5 and collagen1a1 expression (P < 0.05). Notably, I148M cells display reduced peroxisome proliferator-activated receptor gamma transcriptional activity, and this effect was attributed to increased c-Jun N-terminal kinase, thereby inhibiting peroxisome proliferator-activated receptor gamma through serine 84 phosphorylation and promoting activator protein 1 transcription. Conversely, the c-Jun N-terminal kinase inhibitor SP600125 and the peroxisome proliferator-activated receptor gamma agonist rosiglitazone decreased activator protein 1 promoter activity. Conclusions: These data indicate that PNPLA3 is required for HSC activation and that its genetic variant I148M potentiates the profibrogenic features of HSCs, providing a molecular mechanism for the higher risk of progression and severity of liver diseases conferred to patients carrying the I148M variant.