Autophagy and LC3-associated phagocytosis in intestinal epithelial cells

摘要 肠上皮细胞是维持机体与外界屏障的重要细胞膜， 贩运对建立和维持这一障碍至关重要。异常膜 运输可导致屏障受损，从而导致肠道疾病，包括炎症性肠病。 自噬是一种特殊的膜运输过程，允许细胞对细胞内的变化做出反应。 新陈代谢.此外，自噬对于维持上皮屏障和先天性免疫也是重要的。 反应，介导细胞内病原体的分离和降解。此外，LC 3相关 吞噬作用（phagocytosis，简称ERF）对于病原体的摄取和降解是重要的，并且该途径的功能障碍是 与炎症有关重要的是，自噬和凋亡途径中的蛋白质变体具有 与炎症性肠病（IBD），特别是克罗恩病的易感性增加有关， 尽管这种联系背后的分子机制仍不完全清楚。MAMDC 4是 一种定位于肠上皮细胞内体的完整膜蛋白。MAMDC 4缺失 损害了肠上皮细胞的形态，RNAseq研究表明MAMDC 4是下降的- 在IBD中调节。在以前的工作中，我们发现MAMDC 4与小的GTTRab 14相互作用。在 Rab 14是一种专职吞噬细胞，它被招募到吞噬体中，阻止吞噬体-溶酶体融合，但它的 在肠上皮中的作用尚不清楚。在我们的初步数据中，我们表明Rab 14存在于 自噬体和Rab 14和MAMDC 4都存在于含有入侵细菌的膜上。 此外，MAMDC 4的缺失导致自噬和溶酶体标记物在肾小管上皮细胞上的积累， 膜。这些结果表明MAMDC 4和Rab 14在分子网络中起作用，以维持粘膜 通过控制自噬或自噬来增强免疫力。在这个提议中，我们将使用培养的肠上皮细胞， 类器官培养和患者来源的类器官，以确定自噬和/或自噬在肠上皮细胞中的作用。 体内平衡

Abstract The intestinal epithelium is vital to maintain the barrier between the body and the outside world, and membrane trafficking is essential for both the development and maintenance of this barrier. Abnormal membrane trafficking can result compromised barrier leading to intestinal disease, including inflammatory bowel disease. Autophagy is a specialized membrane trafficking process that allows cells to respond to changes in metabolism. In addition, autophagy is important for maintenance of the epithelial barrier and the innate immune response, mediating the isolation and degradation of intracellular pathogens. Furthermore, LC3-associated phagocytosis (LAP) is important for uptake and degradation of pathogens, and dysfunction of this pathway is associated with hyperinflammation. Importantly, variants of proteins in the autophagic and LAP pathways have been linked to increased susceptibility to Inflammatory Bowel Disease (IBD), and particularly Crohn’s disease, although the molecular mechanisms that underlie this connection remain incompletely understood. MAMDC4 is an integral membrane protein that localizes to endosomes of the intestinal epithelium. Deletion of MAMDC4 compromises intestinal enterocyte morphology, and RNAseq studies have indicated that MAMDC4 is down- regulated in IBD. In previous work, we found that MAMDC4 interacts with the small GTPase Rab14. In professional phagocytes, Rab14 is recruited to phagosomes and prevents phagosome-lysosome fusion but its role in the intestinal epithelium is unknown. In our preliminary data, we show that Rab 14 is present on autophagosomes and both Rab14 and MAMDC4 are present on membranes containing invading bacteria. Furthermore, deletion of MAMDC4 results in accumulation of autophagy and lysosomal markers on tubular membranes. These results suggest that MAMDC4 and Rab14 act in a molecular network to maintain mucosal immunity through control of autophagy or LAP. In this proposal we will use intestinal epithelial cells in culture, organoid culture, and patient-derived organoids to define the role of autophagy and/or LAP in intestinal homeostasis.