自噬降解与内体运输途径的联系鲜为人知。在这里,我们筛选了一组影响膜转运的未表征的果蝇突变体,以鉴定在自噬中也有作用的新基因。我们在Snap29(突触体相关蛋白29kDa)中分离出功能缺失突变体,编码人类蛋白质SNAP29的果蝇同源物的基因,并在体内表征了其功能。Snap29在其N末端包含2个可溶性NSF附着蛋白受体(SNARE)结构域和一个天冬酰胺-脯氨酸-苯丙氨酸(NPF基序),并且挽救实验表明,这两个SNARE结构域都是功能所必需的。而NPF基序在一定程度上是可有可无的。我们发现Snap29与SNARE蛋白相互作用,局限于多个贩运细胞器,并且是蛋白质运输和正确的高尔基体形态所必需的。缺乏Snap29的发育组织显示出独特的上皮结构缺陷,并积累了大量的自噬体,强调Snap29在自噬和分泌中的主要作用。自噬基因的突变体不显示上皮结构或分泌缺陷,这表明Snap29突变体的这些改变不太可能是由自噬受损引起的。相比之下,我们发现Hop-Stat92E(跳跃式信号转导和92E转录蛋白激活剂)配体水平升高的证据,受体,和相关的信令,这可能是上皮缺陷的基础。总之,我们的发现支持Snap29在膜贩运的关键步骤中的作用,并预测信号传导缺陷可能有助于大脑发育不全的发病机理,神经病,鱼鳞病,和掌plant角化病(CEDNIK),由于失去Snap29而导致的人类先天性综合征。
How autophagic degradation is linked to endosomal trafficking routes is little known. Here we screened a collection of uncharacterized Drosophila mutants affecting membrane transport to identify new genes that also have a role in autophagy. We isolated a loss of function mutant in Snap29 (Synaptosomal-associated protein 29 kDa), the gene encoding the Drosophila homolog of the human protein SNAP29 and have characterized its function in vivo. Snap29 contains 2 soluble NSF attachment protein receptor (SNARE) domains and a asparagine-proline-phenylalanine (NPF motif) at its N terminus and rescue experiments indicate that both SNARE domains are required for function, whereas the NPF motif is in part dispensable. We find that Snap29 interacts with SNARE proteins, localizes to multiple trafficking organelles, and is required for protein trafficking and for proper Golgi apparatus morphology. Developing tissue lacking Snap29 displays distinctive epithelial architecture defects and accumulates large amounts of autophagosomes, highlighting a major role of Snap29 in autophagy and secretion. Mutants for autophagy genes do not display epithelial architecture or secretion defects, suggesting that the these alterations of the Snap29 mutant are unlikely to be caused by the impairment of autophagy. In contrast, we find evidence of elevated levels of hop-Stat92E (hopscotch-signal transducer and activator of transcription protein at 92E) ligand, receptor, and associated signaling, which might underlie the epithelial defects. In summary, our findings support a role of Snap29 at key steps of membrane trafficking, and predict that signaling defects may contribute to the pathogenesis of cerebral dysgenesis, neuropathy, ichthyosis, and palmoplantar keratoderma (CEDNIK), a human congenital syndrome due to loss of Snap29.