SPE-39 Family Proteins Interact with the HOPS Complex and Function in Lysosomal Delivery

• Type of Material: Article
• Authors: Guang-dan Zhu, Emory University; Gloria Salazar, Emory University; Stephanie A. Zlatic, Emory University; Babar Fiza, University of North Carolina at Chapel Hill; Michele M. Doucette, Georgia State University; Craig Heilman, Emory University; Allan I Levey, Emory University; Victor Faundez, Emory University; Steven L'Hernault, Emory University
• Language: English
• Date: 2009-02-15
• Publisher: American Society for Cell Biology
• Publication Version: Final Published Version
• Copyright Statement: © 2009 by The American Society for Cell Biology
• Final Published Version (URL): http://www.molbiolcell.org/content/20/4/1223
• Title of Journal or Parent Work: Molecular Biology of the Cell
• ISSN: 1059-1524
• Volume: 20
• Issue: 4
• Start Page: 1223
• End Page: 1240
• Grant/Funding Information: This work was also supported by National Institutes of Health grants GM-40697 and GM-082932 (to S.W.L.) and NS-42599 and GM-077569 (to V. F.), funds from Emory College, and an Emory University Research Committee award.
• Research Categories: Biology, Molecular; Biology, Cell; Biology, Neuroscience

Abstract

Yeast and animal homotypic fusion and vacuole protein sorting (HOPS) complexes contain conserved subunits, but HOPS-mediated traffic in animals might require additional proteins. Here, we demonstrate that SPE-39 homologues, which are found only in animals, are present in RAB5-, RAB7-, and RAB11-positive endosomes where they play a conserved role in lysosomal delivery and probably function via their interaction with the core HOPS complex. Although Caenorhabditis elegans spe-39 mutants were initially identified as having abnormal vesicular biogenesis during spermatogenesis, we show that these mutants also have disrupted processing of endocytosed proteins in oocytes and coelomocytes. C. elegans SPE-39 interacts in vitro with both VPS33A and VPS33B, whereas RNA interference of VPS33B causes spe-39–like spermatogenesis defects. The human SPE-39 orthologue C14orf133 also interacts with VPS33 homologues and both coimmunoprecipitates and cosediments with other HOPS subunits. SPE-39 knockdown in cultured human cells altered the morphology of syntaxin 7-, syntaxin 8-, and syntaxin 13-positive endosomes. These effects occurred concomitantly with delayed mannose 6-phosphate receptor-mediated cathepsin D delivery and degradation of internalized epidermal growth factor receptors. Our findings establish that SPE-39 proteins are a previously unrecognized regulator of lysosomal delivery and that C. elegans spermatogenesis is an experimental system useful for identifying conserved regulators of metazoan lysosomal biogenesis.