Fusion of monocytes and macrophages with HIV-1 correlates with biochemical properties of CXCR4 and CCR5
Summary
This summary is machine-generated.Human macrophages are more susceptible to M-tropic HIV-1 than T-tropic strains due to altered CXCR4 co-receptor forms. High-molecular-weight CXCR4 on macrophages prevents CD4 association, hindering T-tropic HIV-1 entry.
Area Of Science
- Immunology
- Virology
- Cell Biology
Background
- Human immunodeficiency virus type 1 (HIV-1) entry into host cells requires the CD4 receptor and co-receptors like CXCR4 and CCR5.
- Macrophages are generally more resistant to T-tropic HIV-1 strains compared to M-tropic strains, despite expressing both co-receptors.
Purpose Of The Study
- To investigate the molecular differences in CXCR4 and CCR5 co-receptors between monocytes and macrophages.
- To determine how these co-receptor differences affect their association with CD4 and influence HIV-1 tropism.
Main Methods
- Western blot analysis of total cell extracts and surface proteins from human monocytes and macrophages.
- Co-precipitation assays to assess the association between CD4, CXCR4, and CCR5.
Main Results
- Macrophages display a high-molecular-weight (90 kDa) form of CXCR4 on their surface, unlike monocytes where CXCR4 is primarily monomeric.
- CCR5 remains monomeric in both cell types.
- CD4 constitutively associates with monomeric CXCR4 and CCR5 in both cell types.
- CD4 does not co-precipitate with the high-molecular-weight CXCR4 species found on macrophages.
Conclusions
- The high-molecular-weight CXCR4 species on macrophages are unavailable for CD4 association.
- This altered CXCR4 conformation and lack of CD4 binding may explain the inefficient entry of T-tropic HIV-1 strains into mature macrophages.
- Understanding co-receptor dynamics is crucial for developing strategies against HIV-1 infection.
View abstract on PubMed