Regulation of Hepatic Fibrogeneiss by TANGO1

TANGO1 对肝纤维形成的调节

• 批准号: 9447570
• 负责人: Jessica L Maiers
• 金额: $ 14.8万
• 依托单位: MAYO CLINIC ROCHESTER
• 依托单位国家: 美国
• 财政年份: 2018
• 资助国家: 美国
• 起止时间: 2018-02-05 至 2022-12-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/9447570
• 关键词: Apoptosis; Cicatrix; Cirrhosis; Collagen; Complex; Data; Deposition; Development; Endoplasmic Reticulum; Extracellular Matrix Proteins; Failure; Fibrosis; Foundations; Genetic Screening; Genetic Transcription; Genetically Engineered Mouse; Goals; Hepatic; Hepatic Fibrogenesis; Hepatic Stellate Cell; Hepatocyte; In Vitro; Knock-out; Knowledge; Lead; Ligation; Liver Cirrhosis; Liver Fibrosis; Liver diseases; Mediating; Methods; Molecular; Mus; Pathway interactions; Process; Procollagen; Proteins; Regulation; Research; Resolution; Role; Signal Transduction; Site; Testing; Tissues; Transforming Growth Factor beta; Up-Regulation; Vesicle; Work; XBP1 gene; base; bile duct; clinically relevant; endoplasmic reticulum stress; fibrogenesis; in vivo; knock-down; liver injury; mouse model; new therapeutic target; recruit; response; success; tool; trafficking; transcription factor

Abstract Liver cirrhosis is the leading cause of end-stage liver disease. A hallmark of cirrhosis is fibrogenesis: secretion and deposition of excess extracellular matrix (ECM) proteins by hepatic stellate cells (HSCs). Prominent among secreted ECM proteins is collagen I. Although the role of collagen I deposition in cirrhosis is well known, therapies aimed at disrupting fibrogenesis are lacking. This is due in part to our poor understanding of procollagen I trafficking through the secretory pathway. Fibrogenic signals such as TGFβ drive expression of the collagen I precursor procollagen I, which is subsequently cotranslationed into the endoplasmic reticulum (ER). Procollagen I fibrils oligomerize within the ER, forming a complex too large (~300nm) to package into canonical ER export vesicles (60-90nm). Thus, additional, unknown cellular machinery is necessary for procollagen I trafficking. If this machinery is disrupted, procollagen fibrils would be retained in the ER and lead to ER stress, activation of the unfolded protein response (UPR), and possibly apoptosis. Recent elegant studies performed in non-liver cells suggested that TANGO1 is critical for the transport of procollagens. Whether TANGO1 facilitates ER export and secretion of collagen I from HSCs, a critical step in fibrogenesis, is unknown. We hypothesize that TANGO1 drives procollagen I export from the ER, requires UPR signaling to mediate this effect, and together TANGO1 and the UPR are critical for fibrogenesis in vivo. This hypothesis is based on preliminary data showing (a) TANGO1 knockdown disrupts procollagen I ER export, leading to UPR signaling and HSC apoptosis, (b) TANGO1 expression is mediated, at least in part, by the UPR-activated transcription factor XBP1, and (c) TANGO1+/- mice are protected from cirrhosis development. The novelty and relevance of studying the role of TANGO1 in procollagen I trafficking and its regulation are two-fold: 1) we can identify new targets to disrupt collagen I secretion in fibrogenesis, and 2) failure to resolve ER stress driven by procollagen I retention may lead to HSC apoptosis. The latter mechanism is favorable for fibrosis resolution. Our long-term goal is to elucidate mechanisms of procollagen I trafficking within HSCs and identify novel therapeutic targets to treat liver cirrhosis. The research proposed here will utilize rigorous in vitro and in vivo approaches to unveil the mechanisms of TANGO1-mediated procollagen I trafficking in HSCs, the regulatory relationship between TANGO1 and the UPR during HSC activation, and finally the role of TANGO1 and the UPR in fibrogenesis and fibrosis regression.

抽象的 肝硬化是终末期肝病的主要原因，肝硬化的一个标志是纤维化：分泌。 肝星状细胞 (HSC) 沉积过量的细胞外基质 (ECM) 蛋白。 在分泌的 ECM 蛋白中，有 I 型胶原蛋白。虽然 I 型胶原蛋白沉积在肝硬化中的作用尚不清楚 众所周知，缺乏旨在破坏纤维发生的疗法，部分原因是我们对纤维发生的了解不足。 I 型前胶原通过分泌途径运输，例如 TGFβ 驱动 I 型前胶原的表达。 I 型胶原蛋白前体 I 型前胶原，随后共翻译到内质网中 (ER)。原胶原 I 原纤维在 ER 内寡聚，形成太大（约 300 nm）而无法封装的复合物。 典型的 ER 输出囊泡 (60-90nm) 因此，需要额外的、未知的细胞机制。 如果该机制被破坏，原胶原纤维将保留在 ER 中并导致前胶原 I 运输。 ER 应激、未折叠蛋白反应 (UPR) 的激活以及可能的细胞凋亡。 在非肝细胞中进行的研究表明 TANGO1 对于前胶原蛋白的运输至关重要。 TANGO1 是否促进 ER 输出和 HSC 分泌 I 型胶原蛋白（纤维形成的关键步骤）是 我们探索了 TANGO1 驱动前胶原 I 从 ER 输出，需要 UPR。 TANGO1 和 UPR 一起对于体内纤维形成至关重要。 该假设基于初步数据，显示 (a) TANGO1 敲除会破坏前胶原 I ER 输出，导致 UPR 信号传导和 HSC 凋亡，(b) TANGO1 表达至少部分由 UPR 激活的转录因子 XBP1，以及 (c) TANGO1+/- 小鼠免受肝硬化 研究 TANGO1 在 I 型前胶原贩运及其作用中的新颖性和相关性。 调节有两个方面：1）我们可以确定新的靶标来破坏纤维形成中 I 型胶原蛋白的分泌，2） 未能解决 I 型前胶原滞留引起的 ER 应激可能导致 HSC 凋亡。 有利于纤维化的解决。我们的长期目标是阐明 I 型前胶原蛋白运输的机制。 HSC 并确定治疗肝硬化的新治疗靶点。 严格的体外和体内方法揭示了 TANGO1 介导的前胶原 I 的机制 HSC 的贩运、HSC 激活过程中 TANGO1 和 UPR 之间的调节关系，以及 最后是 TANGO1 和 UPR 在纤维发生和纤维化消退中的作用。