Modulation of Rab7-Dependent Degradative Pathways by Novel Adenovirus Protein

内吞作用具有许多重要的功能， 营养物质对细胞表面受体表达和信号传导的调节， 维持细胞极性和抗原呈递。许多细胞内病原体 劫持内吞途径以侵入细胞、增殖并确保病原体 生存了解病原体感染的后果， 了解内吞运输机制。分离的致病基因 也被用于抑制与其细胞靶点相关的病理过程， 人类疾病模型该提案的重点是了解分子和 早期细胞编码的完整膜蛋白所采用的细胞机制 人类腺病毒的第3区，称为RID <$，最初被确定是因为 它的能力，转向组成型回收EGF受体的溶酶体。我们有 最近发现，RID与RILP和ORP 1 L相互作用，RILP和ORP 1 L是两种已知的效应物， Rab 7 GT3控制从早期到晚期内体的转运，然后再到 溶酶体重要的是，RID可以补偿Rab 7的功能丧失，这表明 通过协调Rab 7效应物的募集来改变内体膜动力学 到通常被认为是早期分类内体的隔室。对我们 这是第一个由Rab 7功能的DNA病毒编码的蛋白质 模仿与其他小GTP酶类似，Rab 7通过在活性GTP- 一个是不活跃的GDP约束国。相反，RID是一种非酶促的 与Rab 7缺乏任何序列同源性的内在膜蛋白，提供了一种 趋同进化的一个显著例子四个具体目标将检验这些目标。 假设1)RID通过募集RILP控制微管依赖性囊泡转运 和ORP 1 L，其随后激活负末端导向的动力蛋白-动力蛋白马达。2）。摆脱 RILP促进ESCRT-II依赖性EGF受体分选，不依赖于受体 酪氨酸激酶或泛素状态。3)RID-ORP 1 L调节胆固醇流出 内体是维持细胞内适当脂质平衡所必需的。4)摆脱 在生产性腺病毒感染期间补偿Rab 7功能丧失，和 通过干扰TNF-α-EGF减轻腺病毒诱导的炎症性疾病 调节IL-8产生的受体信号级联。这些研究将 为膜蛋白运输的细胞生物学提供了新的见解， 腺病毒诱导的炎症性疾病的分子基础。

Endocytosis serves many important functions ranging from acquisition of extracellular nutrients to regulation of cell surface receptor expression and signal transduction, maintenance of cell polarity, and antigen presentation. Many intracellular pathogens hijack endocytic pathways in order to invade cells, proliferate, and ensure pathogen survival. Understanding the consequences of pathogenic infection has enabled greater understanding of the endocytic trafficking machinery. Isolated pathogenic genes have also been used to curb pathological processes associated with their cellular targets in human disease models. The focus of this proposal is to understand the molecular and cellular mechanisms employed by an integral membrane protein encoded by the early region 3 of human adenoviruses called RID¿, which was originally identified because of its ability to divert constitutively recycling EGF receptors to lysosomes. We have recently discovered that RID¿ interacts with RILP and ORP1L, two known effectors for the Rab7 GTPase that governs transport from early to late endosomes and then to lysosomes. Importantly, RID¿ compensates for Rab7 loss-of-function, suggesting it modifies endosome membrane dynamics by coordinating recruitment of Rab7 effectors to compartments that would ordinarily be perceived as early sorting endosomes. To our knowledge this is the first protein encoded by a DNA virus that functions by Rab7 mimicry. Similar to other small GTPases, Rab7 acts by cycling between an active GTP- bound state and an inactive GDP-bound state. In contrast RID¿ is a non-enzymatic intrinsic membrane protein that lacks any sequence homology to Rab7, providing a remarkable example of convergent evolution. Four specific aims will test these hypotheses. 1) RID¿ controls microtubule-dependent vesicle transport by recruiting RILP and ORP1L which then activate minus end-directed dynein-dynactin motors. 2). RID¿- RILP facilitates ESCRT-II-dependent EGF receptor sorting independent of receptor tyrosine kinase or ubiquitin status. 3) RID¿-ORP1L regulates cholesterol efflux from endosomes necessary to maintain the proper lipid balance in cells. 4) RID¿ compensates for Rab7 loss-of-function during a productive adenovirus infection, and blunts adenovirus-induced inflammatory disease by interfering with a TNF¿-EGF receptor signaling cascade that regulates IL-8 production. Altogether these studies will provide novel insights to the cell biology of membrane protein trafficking, and also the molecular basis for adenovirus-induced inflammatory disease.