Roles of Retromer Complex in Development

描述(由申请人提供)：该项目的长期目标是了解逆转录聚体在发育过程中控制细胞过程的分子机制。逆转录聚体是一种进化上保守的多亚基复合体，由两个复合体组成，即货物识别Vps26-Vps29-VPS35杂三聚体和膜靶向杂二聚体或同源二聚体。在酵母和哺乳动物细胞培养中的早期研究表明，它在调节多种蛋白质的内体-高尔基体运输中发挥作用，其中包括哺乳动物的阳离子非依赖性甘露糖-6-磷酸受体。然而，直到最近，逆转聚体复合体在发育中的作用才被研究。我们最近的研究揭示了逆转聚体复合体在Wnt分泌中的重要作用。我们发现，逆转录聚体参与了Wnless(Wls)的内体到高尔基体的运输，Wls是一种分泌Wnt所需的七次跨膜蛋白。在缺乏逆转聚体活性的情况下，Wls是不稳定的，并被降解，从而导致Wnt分泌缺陷。重要的是，虽然逆转聚体不参与许多其他发育信号通路，但我们发现逆转录聚体对其他两个重要的发育过程至关重要，包括(1)果蝇胚胎发生过程中上皮细胞的顶基极性和(2)幼虫发育过程中的造血细胞。我们的初步研究表明，逆转录酶调控Crumbs(CRB)的转运以控制上皮细胞的顶基极性，同时也参与调节Toll/Back信号通路以控制造血。因此，我们的研究揭示了逆转录复合体在发育中的三个重要作用。在这一应用中，我们将进一步研究逆转聚体在Wnt分泌、根尖基底极性控制和Toll/背部信号通路中的作用。在Aim1中，我们将研究泛素化和逆聚体在调节WLS稳定性和循环中的作用。在AIM2中，我们将研究逆转录是否通过调节碎屑的运输和稳定性来控制上皮细胞的极性。在Aim3中，我们将确定Retrmer调节通行费贩运和信号的机制。总之，我们提出的研究将为逆转录分子在发育过程中调节Wnt分泌、上皮极性和Toll/背部信号的机制提供新的见解。 公共卫生相关性：逆转录酶控制Wnt和Toll信号通路以及上皮细胞的极性。这些信号通路和细胞生物学过程对胚胎发育至关重要。Wnt和Toll信号通路的缺陷以及上皮细胞的极性缺陷与包括癌症在内的许多人类疾病有关。这一应用的结果将有助于理解相关的人类疾病过程。

DESCRIPTION (provided by applicant): The long-term goal of this project is to understand the molecular mechanisms by which retromer controls cellular processes during development. Retromer is an evolutionarily conserved multi-subunit complex, consisting of two complexes, the cargo recognition Vps26-Vps29- Vps35 heterotrimer and a membrane-targeting heterodimer or homodimer. Early studies in yeast and mammalian cell culture have demonstrated its roles in mediating endosome-Golgi trafficking of several proteins including mammalian cation-independent mannose-6-phosphate receptor. However, the roles of retromer complex in development have not been examined until recently. Our recent studies have uncovered an essential role of retromer complex in Wnt secretion. We showed that retromer is involved in endosome-to-Golgi transport of Wntless (Wls), a seven-pass transmembrane protein required for Wnt secretion. In the absence of retromer activity, Wls is unstable and is degraded, thereby causing Wnt secretion defects. Importantly, while retromer is not involved in many other developmental signaling pathways, we found that retromer is crucial for other two essential developmental processes including (1) the apicobasal polarity of epithelium during Drosophila embryogenesis and (2) hematopoeisis during larval development. Our preliminary studies have demonstrated that retromer regulates the trafficking of Crumbs (crb) to control the apicobasal polarity of epithelium, while it is involved in regulating Toll/Dorsal signaling pathway to control hematopoeisis. Thus, our studies have uncovered three essential roles of the retromer complex in development. In this application, we will further investigate the roles of retromer in Wnt secretion, in the apicobasal polarity control and in Toll/dorsal signaling pathway. In Aim1, we will examine the roles of ubiquitination and retromer in regulating Wls stability and recycling. In Aim2, we will examine whether retromer controls epithelium polarity by regulating Crumb trafficking and stability. In Aim3, we will determine the mechanism by which retromer regulates Toll trafficking and signaling. Together, our proposed studies will provide new insights into the mechanisms by which retromer regulates Wnt secretion, epithelium polarity and Toll/dorsal signaling during development. PUBLIC HEALTH RELEVANCE: Retromer controls Wnt and Toll signaling pathways as well as epithelium polarity. These signaling pathways and cell biology processes are essential for embryonic development. Defects in Wnt and Toll signaling pathways as well as epithelium polarity are associated with many human diseases including cancers. The outcomes of this application will help understanding related human disease processes.