Pulipparacharuvil Suprabha, Akbar Mohammed Ali, Ray Sanchali, Sevrioukov Evgueny A, Haberman Adam S, Rohrer Jack, Krämer Helmut
Center for Basic Neuroscience, UT Southwestern Medical Center, 5323 Harry Hines Blvd, Dallas, TX 75390-9111, USA.
J Cell Sci. 2005 Aug 15;118(Pt 16):3663-73. doi: 10.1242/jcs.02502. Epub 2005 Jul 26.
Mutations that disrupt trafficking to lysosomes and lysosome-related organelles cause multiple diseases, including Hermansky-Pudlak syndrome. The Drosophila eye is a model system for analyzing such mutations. The eye-color genes carnation and deep orange encode two subunits of the Vps-C protein complex required for endosomal trafficking and pigment-granule biogenesis. Here we demonstrate that dVps16A (CG8454) encodes another Vps-C subunit. Biochemical experiments revealed a specific interaction between the dVps16A C-terminus and the Sec1/Munc18 homolog Carnation but not its closest homolog, dVps33B. Instead, dVps33B interacted with a related protein, dVps16B (CG18112). Deep orange bound both Vps16 homologs. Like a deep orange null mutation, eye-specific RNAi-induced knockdown of dVps16A inhibited lysosomal delivery of internalized ligands and interfered with biogenesis of pigment granules. Ubiquitous knockdown of dVps16A was lethal. Together, these findings demonstrate that Drosophila Vps16A is essential for lysosomal trafficking. Furthermore, metazoans have two types of Vps-C complexes with non-redundant functions.
破坏向溶酶体和溶酶体相关细胞器转运的突变会引发多种疾病，包括赫尔曼斯基-普德拉克综合征。果蝇眼睛是分析此类突变的模型系统。眼色基因康乃馨和深橙色编码内体转运和色素颗粒生物发生所需的Vps-C蛋白复合物的两个亚基。在此我们证明dVps16A（CG8454）编码另一个Vps-C亚基。生化实验揭示了dVps16A C末端与Sec1/Munc18同源物康乃馨之间存在特异性相互作用，但与它最接近的同源物dVps33B不存在这种相互作用。相反，dVps33B与一种相关蛋白dVps16B（CG18112）相互作用。深橙色与两种Vps16同源物都结合。与深橙色无效突变一样，眼睛特异性RNAi诱导的dVps16A敲低抑制了内化配体向溶酶体的转运，并干扰了色素颗粒的生物发生。dVps16A的全身性敲低是致死性的。总之，这些发现表明果蝇Vps16A对于溶酶体转运至关重要。此外，后生动物有两种功能不冗余的Vps-C复合物。
