Synectin promotes fibrogenesis by regulating PDGFR isoforms through distinct mechanisms
Synectin promotes fibrogenesis by regulating PDGFR isoforms through distinct mechanisms
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Synectin 通过不同的机制调节 PDGFR 亚型来促进纤维发生
DOI：
10.1172/jci.insight.92821
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发表时间：
2017-12-21
期刊：
影响因子：
8
通讯作者：
Shah, Vijay H.
中科院分区：
文献类型：
--
作者：
Drinane, Mary C.;Yaqoob, Usman;Shah, Vijay H.
支架蛋白连接蛋白在膜受体途径的运输和调节中起关键作用。由于血小板源性生长因子受体（PDGFR）是肝星状细胞（HSC）活化和肝纤维化所必需的，我们试图确定粘连蛋白对PDGFR通路和肝纤维化发展的作用。发现从HSC中缺失粘连蛋白的小鼠免受肝纤维化。mRNA测序显示，在HSC中敲低聚结蛋白证明了包括PDGFR-β在内的基因的纤维化途径的减少。PDGFR-β启动子的染色质IP测定在连接蛋白敲低后揭示了依赖于p300组蛋白乙酰转移酶的与转录降低相关的组蛋白标记的模式。发现Synectin敲低也下调PDGFR-α蛋白水平，但通过另一种机制：保护免受自噬降解。定点突变显示，特异性PDGFR-α赖氨酸残基的泛素化是其自噬降解的原因。此外，功能研究表明，降低血小板源性生长因子依赖的迁移和增殖的HSC后，synectin敲低。最后，人类肝硬化表现出增加的连接蛋白的蛋白质水平。这项工作提供了深入了解不同的转录和翻译后机制的连接蛋白调节PDGFRs，这是至关重要的纤维化。
The scaffold protein synectin plays a critical role in the trafficking and regulation of membrane receptor pathways. As platelet-derived growth factor receptor (PDGFR) is essential for hepatic stellate cell (HSC) activation and liver fibrosis, we sought to determine the role of synectin on the PDGFR pathway and development of liver fibrosis. Mice with deletion of synectin from HSC were found to be protected from liver fibrosis. mRNA sequencing revealed that knockdown of synectin in HSC demonstrated reductions in the fibrosis pathway of genes, including PDGFR-beta. Chromatin IP assay of the PDGFR-beta promoter upon synectin knockdown revealed a pattern of histone marks associated with decreased transcription, dependent on p300 histone acetyltransferase. Synectin knockdown was found to downregulate PDGFR-a protein levels, as well, but through an alternative mechanism: protection from autophagic degradation. Site-directed mutagenesis revealed that ubiquitination of specific PDGFR-a lysine residues was responsible for its autophagic degradation. Furthermore, functional studies showed decreased PDGF-dependent migration and proliferation of HSC after synectin knockdown. Finally, human cirrhotic livers demonstrated increased synectin protein levels. This work provides insight into differential transcriptional and posttranslational mechanisms of synectin regulation of PDGFRs, which are critical to fibrogenesis.