Defective HIV-1 particle assembly in AP-3-deficient cells derived from patients with Hermansky-Pudlak syndrome type 2

J Virol. 2012 Oct;86(20):11242-53. doi: 10.1128/JVI.00544-12. Epub 2012 Aug 8.

Abstract

Adaptor protein complex 3 (AP-3) is a heterotetramer that is involved in signal-mediated protein sorting to endosomal-lysosomal organelles. AP-3 deficiency in humans, induced by mutations in the AP3B1 gene, which encodes the β3A subunit of the AP-3 complex, results in Hermansky-Pudlak syndrome 2 (HPS2), which is a rare genetic disorder with defective lysosome-related organelles. In a previous study, we identified the AP-3 complex as an important contributor to HIV-1 assembly and release. We hypothesized that cells from patients affected by HPS2 should demonstrate abnormalities of HIV-1 assembly. Here we report that HIV-1 particle assembly and release are indeed diminished in HPS2 fibroblast cultures. Transient or stable expression of the full-length wild-type β3A subunit in HPS2 fibroblasts restored the impaired virus assembly and release. In contrast, virus-like particle release mediated by MA-deficient Gag mutants lacking the AP-3 binding site was not altered in HPS2 cells, indicating that the MA domain serves as the major viral determinant required for the recruitment of the AP-3 complex. AP-3 deficiency decreased HIV-1 Gag localization at the plasma membrane and late endosomes and increased the accumulation of HIV-1 Gag at an intermediate step between early and late endosomes. Blockage of the clathrin-mediated endocytic pathway in HPS2 cells did not reverse the inhibited virus assembly and release imposed by the AP-3 deficiency. These results demonstrate that the intact and stable AP-3 complex is required for HIV-1 assembly and release, and the involvement of the AP-3 complex in late stages of the HIV-1 replication cycle is independent of clathrin-mediated endocytosis.

Publication types

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

MeSH terms

  • Adaptor Protein Complex 3 / deficiency
  • Adaptor Protein Complex 3 / genetics
  • Adaptor Protein Complex 3 / metabolism*
  • Adaptor Protein Complex delta Subunits / deficiency
  • Adaptor Protein Complex delta Subunits / genetics
  • Adaptor Protein Complex delta Subunits / metabolism*
  • Cell Membrane / metabolism
  • Cell Membrane / virology
  • Cells, Cultured
  • Clathrin / antagonists & inhibitors
  • Endocytosis
  • Fibroblasts / virology
  • HIV-1 / metabolism
  • HIV-1 / physiology*
  • Hermanski-Pudlak Syndrome* / genetics
  • Hermanski-Pudlak Syndrome* / metabolism
  • Hermanski-Pudlak Syndrome* / virology
  • Humans
  • Mutation
  • Signal Transduction
  • Skin / virology
  • Virus Assembly*
  • Virus Release / genetics
  • gag Gene Products, Human Immunodeficiency Virus / genetics
  • gag Gene Products, Human Immunodeficiency Virus / metabolism*

Substances

  • AP3D1 protein, human
  • Adaptor Protein Complex 3
  • Adaptor Protein Complex delta Subunits
  • Clathrin
  • gag Gene Products, Human Immunodeficiency Virus

Supplementary concepts

  • Hermansky Pudlak syndrome 2