The productive entry pathway of HIV-1 in macrophages is dependent on endocytosis through lipid rafts containing CD4

PLoS One. 2014 Jan 22;9(1):e86071. doi: 10.1371/journal.pone.0086071. eCollection 2014.

Abstract

Macrophages constitute an important reservoir of HIV-1 infection, yet HIV-1 entry into these cells is poorly understood due to the difficulty in genetically manipulating primary macrophages. We developed an effective genetic approach to manipulate the sub-cellular distribution of CD4 in macrophages, and investigated how this affects the HIV-1 entry pathway. Pluripotent Stem Cells (PSC) were transduced with lentiviral vectors designed to manipulate CD4 location and were then differentiated into genetically modified macrophages. HIV-1 infection of these cells was assessed by performing assays that measure critical steps of the HIV-1 lifecycle (fusion, reverse transcription, and expression from HIV-1 integrants). Expression of LCK (which tethers CD4 to the surface of T cells, but is not normally expressed in macrophages) in PSC-macrophages effectively tethered CD4 at the cell surface, reducing its normal endocytic recycling route, and increasing surface CD4 expression 3-fold. This led to a significant increase in HIV-1 fusion and reverse transcription, but productive HIV-1 infection efficiency (as determined by reporter expression from DNA integrants) was unaffected. This implies that surface-tethering of CD4 sequesters HIV-1 into a pathway that is unproductive in macrophages. Secondly, to investigate the importance of lipid rafts (as detergent resistant membranes - DRM) in HIV-1 infection, we generated genetically modified PSC-macrophages that express CD4 mutants known to be excluded from DRM. These macrophages were significantly less able to support HIV-1 fusion, reverse-transcription and integration than engineered controls. Overall, these results support a model in which productive infection by HIV-1 in macrophages occurs via a CD4-raft-dependent endocytic uptake pathway.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • CD4 Antigens / genetics
  • CD4 Antigens / metabolism*
  • Cell Line
  • Endocytosis / immunology*
  • Gene Expression
  • Gene Knockdown Techniques
  • Gene Order
  • Genetic Vectors
  • HIV Infections / genetics
  • HIV Infections / immunology
  • HIV Infections / metabolism
  • HIV Infections / virology
  • HIV-1 / physiology*
  • Humans
  • Lymphocyte Specific Protein Tyrosine Kinase p56(lck) / genetics
  • Lymphocyte Specific Protein Tyrosine Kinase p56(lck) / metabolism
  • Macrophages / physiology*
  • Macrophages / virology*
  • Membrane Microdomains*
  • Mice
  • Protein Transport
  • Reverse Transcription
  • Virus Internalization*
  • Virus Replication

Substances

  • CD4 Antigens
  • Lymphocyte Specific Protein Tyrosine Kinase p56(lck)