REGULATION OF HEPATIC FIBROGENEISS BY TANGO1

TANGO1 对肝纤维形成的调节

• 批准号: 10369343
• 负责人: Jessica L Maiers
• 金额: $ 8.85万
• 依托单位: INDIANA UNIV-PURDUE UNIV AT INDIANAPOLIS
• 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/10369343
• 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.

摘要 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： 以及肝星状细胞（HSC）沉积过量的细胞外基质（ECM）蛋白。突出 在分泌的ECM蛋白中有胶原I。虽然I型胶原沉积在肝硬化中的作用是好的， 已知缺乏旨在破坏纤维形成的疗法。这部分是由于我们对 前胶原I通过分泌途径运输。纤维化信号如TGFβ驱动 I型胶原前体I型前胶原，其随后聚集到内质网中 （ER）。前胶原I纤维在ER内寡聚化，形成太大（~ 300 nm）而无法包装成的复合物。 典型的ER输出囊泡（60- 90 nm）。因此，额外的，未知的细胞机制是必要的， 前胶原I运输。如果这种机制被破坏，前胶原纤维将保留在ER中，并导致 ER应激，未折叠蛋白反应（UPR）的激活，以及可能的凋亡。最近优雅 在非肝细胞中进行的研究表明TANGO 1对于前胶原的转运是关键的。 TANGO 1是否促进ER输出和HSC分泌胶原I，这是纤维形成的关键步骤， 未知我们假设TANGO 1驱动I型前胶原从ER输出，需要UPR TANGO 1和UPR共同参与了体内纤维化的发生。 该假设基于初步数据，显示（a）TANGO 1敲低破坏前胶原I ER 输出，导致UPR信号传导和HSC凋亡，（B）TANGO 1表达至少部分由 UPR激活的转录因子XBP 1，和（c）TANGO 1 +/-小鼠被保护免于肝硬化 发展研究TANGO 1在I型前胶原运输中的作用及其与疾病关系的新奇和相关性 调节是双重的：1）我们可以确定新的靶点来破坏纤维发生中的胶原蛋白I分泌，以及2） 不能解决由原胶原I滞留驱动的ER应激可能导致HSC凋亡。后一种机制 有利于纤维化消退。我们的长期目标是阐明I型前胶原运输的机制 在HSC内，并确定治疗肝硬化的新的治疗靶点。本文提出的研究将 利用严格的体外和体内方法来揭示TANGO 1介导的I型前胶原的机制 HSC的运输，HSC活化过程中TANGO 1和UPR之间的调节关系，以及 最后是TANGO 1和UPR在纤维化发生和纤维化消退中的作用。