Hermansky-Pudlak syndrome protein complexes associate with phosphatidylinositol 4-kinase type II alpha in neuronal and non-neuronal cells

J Biol Chem. 2009 Jan 16;284(3):1790-802. doi: 10.1074/jbc.M805991200. Epub 2008 Nov 14.

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 alpha (PI4KIIalpha). 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, 1415-1426 ). Using cells deficient in different Hermansky-Pudlak syndrome complexes, we identified that BLOC-1, but not BLOC-2 or BLOC-3, deficiencies affect PI4KIIalpha inclusion into AP-3 complexes. BLOC-1, PI4KIIalpha, and AP-3 belong to a tripartite complex, and down-regulation of either PI4KIIalpha, BLOC-1, or AP-3 complexes led to similar LAMP1 phenotypes. Our analysis indicates that BLOC-1 complex modulates the association of PI4KIIalpha with AP-3. These results suggest that AP-3 and BLOC-1 act, either in concert or sequentially, to specify sorting of PI4KIIalpha along the endocytic route.

Publication types

  • Research Support, N.I.H., Extramural

MeSH terms

  • Adaptor Protein Complex 3 / genetics
  • Adaptor Protein Complex 3 / metabolism*
  • Animals
  • Endocytosis / genetics
  • Endosomes / genetics
  • Endosomes / metabolism*
  • Endosomes / pathology
  • Hermanski-Pudlak Syndrome / genetics
  • Hermanski-Pudlak Syndrome / metabolism
  • Hermanski-Pudlak Syndrome / pathology
  • Humans
  • Membrane Proteins / genetics
  • Membrane Proteins / metabolism*
  • Mice
  • Multiprotein Complexes / genetics
  • Multiprotein Complexes / metabolism*
  • Neurons / metabolism*
  • Neurons / pathology
  • Phosphotransferases (Alcohol Group Acceptor) / genetics
  • Phosphotransferases (Alcohol Group Acceptor) / metabolism*

Substances

  • Adaptor Protein Complex 3
  • HPS1 protein, human
  • Hps1 protein, mouse
  • Membrane Proteins
  • Multiprotein Complexes
  • PIP4K2A protein, human
  • Phosphotransferases (Alcohol Group Acceptor)