Molecular and functional characterization of a membrane contact site between peroxisomes and the endoplasmic reticulum

过氧化物酶体与内质网之间膜接触位点的分子和功能表征

• 批准号: 397476530
• 负责人: Privatdozent Dr. Markus Islinger
• 金额: --
• 依托单位: Institute for Innate Immunoscience (MI3)
• 依托单位国家: 德国
• 项目类别: Research Grants
• 财政年份: 2018
• 资助国家: 德国
• 起止时间: 2017-12-31 至 2020-12-31
• 项目状态: 已结题
• 来源: https://gepris.dfg.de/gepris/projekt/397476530?language=en
• 关键词: Molecular; functional; characterization; membrane; contact

In recent years, organelle contact sites have attracted considerable scientific attention. So far, this research field mainly focused on contact sites either between mitochondria and the endoplasmic reticulum (ER) or between the plasma membrane and the ER. These contact sites are not only responsible for the direct transfer of metabolites but also for interorganellar signaling modifying important cellular processes such as the endoplasmic reticulum (ER) stress response or the mitochondrial apoptosis pathway. Interestingly, close membrane appositions between peroxisomes (PO) and the ER were already documented by early electron microscopic studies. Recently, we have discovered a protein tether between PO and the ER consisting of peroxisomal acyl-CoA binding domain-containing protein 5 (ACBD5) and the vesicle-associated membrane protein-associated protein B (VAPB) of the ER. At the functional level, we hypothesize that this novel ER-PO contact site facilitates metabolite exchange (e.g. ether lipid or phospholipid precursors) between both organelles and thereby contributes to regulation of cellular lipid metabolism or PO proliferation. Importantly, patients with a deletion of ACBD5 have been recently identified, suffering from a very distinct pathological phenotype. This finding clearly underlines the functional significance of ACBD5 for human health. Thus, in order to shed light on the function of the ACBD5/VAPB contact site between ER and PO, we will address the following four specific issues: (1) We will characterize additional interaction partners of ACBD5 and its closest peroxisomal relative ACBD4 in order to gain further information on the function of this protein subfamily. (2) We will analyze the proteomic composition of ER-PO contact sites combining subcellular fractionation/BioID with quantitative mass spectrometry. (3) We will decipher the functional significance of ACBD5 for membrane lipid transfer, import of fatty acids and pexophagy. (4) We will characterize the phenotype of ACBD5 knockout mice in order to unravel pathogenetic mechanisms of ACBD5 deletion and the associated peroxisomal disease. Taken together, the current proposal aims at generating fundamental new data on the structure and function of a novel ER-PO tether.

近年来，细胞器接触点的研究引起了科学界的广泛关注。目前，该领域的研究主要集中在线粒体与内质网之间或质膜与内质网之间的接触部位。这些接触位点不仅负责代谢物的直接转移，而且还负责细胞器间信号传导，调节重要的细胞过程，如内质网（ER）应激反应或线粒体凋亡途径。有趣的是，早期的电镜研究已经证明过氧化物酶体（PO）和内质网之间的膜紧密结合。最近，我们发现了一种由ER的过氧化物酶体酰基辅酶a结合结构域蛋白5 （ACBD5）和囊泡相关膜蛋白相关蛋白B （VAPB）组成的PO与ER之间的蛋白系链。在功能水平上，我们假设这种新的ER-PO接触位点促进了两种细胞器之间代谢物交换（例如醚脂质或磷脂前体），从而有助于调节细胞脂质代谢或PO增殖。重要的是，最近发现了ACBD5缺失的患者，患有非常独特的病理表型。这一发现清楚地强调了ACBD5对人类健康的功能重要性。因此，为了阐明ER和PO之间ACBD5/VAPB接触位点的功能，我们将解决以下四个具体问题：(1)我们将表征ACBD5及其最接近的过氧化物酶体亲戚ACBD4的其他相互作用伙伴，以获得有关该蛋白亚家族功能的进一步信息。(2)我们将结合亚细胞分离/BioID和定量质谱分析ER-PO接触位点的蛋白质组学组成。(3)我们将破译ACBD5在膜脂转移、脂肪酸进口和噬脂方面的功能意义。(4)我们将对ACBD5基因敲除小鼠的表型进行表征，以揭示ACBD5缺失和相关过氧化物酶体疾病的发病机制。综上所述，目前的提案旨在生成关于新型ER-PO系链的结构和功能的基本新数据。