Hermansky-Pudlak Syndrome Protein Complexes Associate withPhosphatidylinositol 4-Kinase Type II α in Neuronal and Non-neuronal Cells

• Type of Material: Article
• Authors: Gloria Salazar, Emory University; Stephanie Zlatic, Emory University; Branch Craige, Emory University; Andrew A. Peden, University of Cambridge; Jan Pohl, Emory University; Victor Faundez, Emory University
• Language: English
• Date: 2009-01-16
• Publisher: American Society for Biochemistry and Molecular Biology
• Publication Version: Final Published Version
• Copyright Statement: © 2009 The American Society for Biochemistry and Molecular Biology, Inc.
• Final Published Version (URL): http://www.jbc.org/content/284/3/1790
• Title of Journal or Parent Work: Journal of Biological Chemistry
• ISSN: 0021-9258
• Volume: 284
• Issue: 3
• Start Page: 1790
• End Page: 1802
• Grant/Funding Information: This article must therefore be hereby marked “advertisement” in accordance with 18 U.S.C. Section 1734 solely to indicate this fact.; The costs of publication of this article were defrayed in part by the payment of page charges.; This work was supported, in whole or in part, by National Institutes of Health Grants NS42599; and GM 077569 (to V. F.).
• Research Categories: Chemistry, Biochemistry; Biology, Cell

Abstract

The Hermansky-Pudlak syndrome is a disorder affecting endosome sorting. Disease is triggered by defects in any of 15 mouse gene products, which are part of five distinct cytosolic molecular complexes: AP-3, homotypic fusion and vacuole protein sorting, and BLOC-1, -2, and -3. To identify molecular associations of these complexes, we used in vivo cross-linking followed by purification of cross-linked AP-3 complexes and mass spectrometric identification of associated proteins. AP-3 was co-isolated with BLOC-1, BLOC-2, and homotypic fusion and vacuole protein sorting complex subunits; clathrin; and phosphatidylinositol-4-kinase type II α (PI4KIIα). We previously reported that this membrane-anchored enzyme is a regulator of AP-3 recruitment to membranes and a cargo of AP-3 (Craige, B., Salazar, G., and Faundez, V. (2008) Mol. Biol. Cell 19,1415 -142618256276). Using cells deficient in different Hermansky-Pudlak syndrome complexes, we identified that BLOC-1, but not BLOC-2 or BLOC-3, deficiencies affect PI4KIIα inclusion into AP-3 complexes. BLOC-1, PI4KIIα, and AP-3 belong to a tripartite complex, and down-regulation of either PI4KIIα, BLOC-1, or AP-3 complexes led to similar LAMP1 phenotypes. Our analysis indicates that BLOC-1 complex modulates the association of PI4KIIα with AP-3. These results suggest that AP-3 and BLOC-1 act, either in concert or sequentially, to specify sorting of PI4KIIα along the endocytic route.