Identifying targetable mechanisms of TMEM38B/TRIC-B in liver fibrosis

鉴定 TMEM38B/TRIC-B 在肝纤维化中的靶向机制

• 批准号: 10216441
• 负责人: Jessica L Maiers
• 金额: $ 15.85万
• 依托单位: INDIANA UNIV-PURDUE UNIV AT INDIANAPOLIS
• 依托单位国家: 美国
• 财政年份: 2021
• 资助国家: 美国
• 起止时间: 2021-05-15 至 2022-05-14
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/10216441
• 关键词: Apoptosis; Area; C-terminal; Cations; Cell Survival; Cells; Cicatrix; Cirrhosis; Clinic; Collagen; Collagen Type I; Communities; Complex; Cytoplasmic Tail; Data; Deposition; Endoplasmic Reticulum; Engineering; Enhancers; Extracellular Matrix; Fibrosis; Genes; Genome; Goals; Hepatic Stellate Cell; Hepatocyte; Human; Impairment; In Vitro; Ion Channel; Liver; Liver Failure; Liver Fibrosis; Mediating; Methyltransferase; Mission; Morphology; Mus; Mutate; Mutation; Nucleic Acid Regulatory Sequences; Osteoblasts; Osteogenesis Imperfecta; Pathologic; Pathway interactions; Patients; Pharmaceutical Preparations; Pharmacology; Physiological; Polycomb; Post-Translational Protein Processing; Post-Translational Regulation; Process; Procollagen; Production; Proteins; Reagent; Regulation; Repressor Proteins; Research; Role; Site-Directed Mutagenesis; Stimulus; System; Tissues; Transforming Growth Factor beta; Up-Regulation; Viral Vector; bone; chronic liver injury; cytokine; endoplasmic reticulum stress; experimental study; fibrogenesis; global health; histone methyltransferase; in vivo; insight; liver injury; liver transplantation; mouse model; mutant; novel; novel therapeutic intervention; prevent; protein transport; response; single-cell RNA sequencing; trafficking

ABSTRACT: Liver fibrosis impacts millions of people globally, with no pharmacologic therapies available to limit fibrosis progression or promote fibrosis regression. The major fibrogenic cells in the liver are Hepatic Stellate Cells (HSCs). Upon liver injury, activated HSCs produce and secrete fibrogenic proteins, including collagen Iα1 and 1α2, which are major component of fibrotic scarring in the liver. Several therapies have aimed to target HSCs to limit fibrogenesis by preventing HSC activation or promoting HSC apoptosis; however these strategies have not been successful in the clinic. We propose that understand the procollagen I trafficking machinery would provide a unique and viable strategy for limiting fibrosis. We performed single cell RNA sequencing on fibrogenic HSCs from mice and found upregulation of the understudied gene TMEM38B in fibrogenic HSCs. TMEM38B is implicated in procollagen I trafficking in bone-producing osteoblasts, and mutations in TMEM38B leads to brittle bones in mice and humans. We hypothesize that TMEM38B is critical for fibrogenesis through mediating procollagen I trafficking and HSC survival, and that targeting TMEM38B could serve as a viable anti- fibrotic strategy. Our preliminary data highlights a key role for TMEM38B in fibrogenesis. TMEM38B expression is increased in patients where liver fibrosis has progressed to cirrhosis, as well as in murine models of liver fibrosis. Secondly, TMEM38B is increased in primary human and mouse HSCs following activation with the pro-fibrotic cytokine TGFβ. Finally, we show that TMEM38B is negatively regulated by the Polycomb Repressor Complex 2 (PRC), a histone methyltransferase complex dysregulated in fibrosis. Disruption of the PRC2 complex leads to increased TMEM38B expression in HSCs, and increased procollagen I deposition in a murine model where key components of the PRC2 complex are deleted from osteoblasts. The experiments proposed here will increase our understanding of TMEM38B in 3 critical areas: 1) Elucidating the critical contribution of TMEM38B to fibrogenic processes, including procollagen I secretion and HSC survival, 2) interrogating the critical domains and post-translational regulation of TMEM38B channel activity, and 3) revealing mechanisms that regulate TMEM38B expression. Completion of the proposed research will provide crucial insight into TMEM38B function and regulation under both physiological and pathophysiological conditions as well as provide novel reagents to share with the research community, with the long term goal of targeting TMEM38B as an anti-fibrotic strategy.

摘要： 肝纤维化影响着全球数百万人，但没有可用的药物治疗来限制纤维化 进展或促进纤维化消退。肝星状细胞是肝纤维化的主要细胞 （HSC）。在肝损伤时，活化的HSC产生并分泌纤维化蛋白，包括胶原I α 1和胶原I α 2。 1 α 2，是肝脏纤维化瘢痕形成的主要成分。几种疗法旨在靶向HSC 通过阻止HSC活化或促进HSC凋亡来限制纤维化;然而，这些策略 在临床上并不成功。我们建议，了解原胶原I运输机制， 为限制纤维化提供了独特且可行的策略。我们进行了单细胞RNA测序， 结果发现，未充分研究的基因TMEM38B在纤维化HSC中上调。 TMEM38 B与骨生成成骨细胞中的前胶原I运输有关，TMEM38 B中的突变 导致老鼠和人类的骨质疏松。我们假设TMEM38 B通过以下途径对纤维形成至关重要： 介导前胶原I运输和HSC存活，靶向TMEM38B可以作为一种可行的抗- 纤维化策略我们的初步数据突出了TMEM38B在纤维发生中的关键作用。TMEM38 B表达 在肝纤维化进展为肝硬化的患者中，以及在肝硬化的小鼠模型中， 纤维化第二，在用TMEM38B活化后，TMEM38B在原代人和小鼠HSC中增加。 促纤维化细胞因子TGF β。最后，我们表明TMEM38 B受到Polycomb的负调节 阻遏物复合物2（PRC），一种在纤维化中失调的组蛋白甲基转移酶复合物。破坏 PRC2复合物导致HSC中TMEM38B表达增加，并导致HSC中I型前胶原沉积增加。 小鼠模型，其中PRC2复合物的关键组分从成骨细胞中缺失。实验 这里提出的建议将增加我们对TMEM38B在3个关键领域的理解：1）阐明关键 TMEM38 B对纤维化过程的贡献，包括前胶原I分泌和HSC存活，2） 询问TMEM 38 B通道活性的关键结构域和翻译后调节，以及3） 揭示了调节TMEM38B表达的机制。完成拟议的研究将提供 对TMEM38B在生理和病理生理条件下的功能和调节的重要见解 条件，并提供新的试剂与研究界分享，长期目标是 靶向TMEM38B作为抗纤维化策略。