The cytoplasmic domain of CD4 plays a critical role during the early stages of HIV infection in T-cells.
The role played by the cytoplasmic domain of the CD4 molecule in the process of HIV infection was investigated, using A2.01 cells which express different forms of the CD4 gene. A delay in HIV production was consistently observed in cells expressing a truncated CD4 which lacks the cytoplasmic domain (CD4.401) compared with cells expressing the wild type CD4. The delay was much less in cells expressing a hybrid CD4-CD8 molecule (amino acids 1-177 of CD4 fused to the hinge, transmembrane and cytoplasmic domains of CD8). Yet the extent of viral entry and reverse transcription, monitored by semi-quantitative PCR, was similar in each cell type studied. For further study of the mechanism responsible for delayed HIV replication in the A2.01/CD4.401 cell line, cells were treated with phytohaemagglutinin (PHA), 24 h after HIV infection. Under such experimental conditions HIV production was detected at the same time in the culture supernatants of A2.01/CD4 and A2.01/CD4.401 cells. Moreover, we found that CD4 oligomerization by HIV-1 induced NF-kappa B translocation in A2.01/CD4 and A2.01/CD4-CD8 but not in A2.01/CD4.401 cells. This was consistent with CAT assay experiments which provided evidence for Tat-independent NF-kappa B mediated activation of HIV-1 LTR promoter after HIV binding to CD4 in A2.01/CD4 and A2.01/CD4-CD8 but not in A2.01/CD4.401 cells. In contrast to results published recently by Tremblay et al. (1994, EMBO J., 13, 774-783), we propose that a positive cellular signal initiated following oligomerization of the CD4 by the virus itself is involved in NF-kappa B-dependent early HIV transcription in A2.01/CD4 cells.
Benkirane
M
M
Laboratoire d'Immunologie des Infections Rétrovirales, CNRS UPR9008 et INSERM U249, Montpellier, France.
Jeang
K T
KT
Devaux
C
C
D001483:Base Sequence; D015704:CD4 Antigens / Q000502:physiology*; D016827:CD8 Antigens / Q000276:immunology; D015500:Chloramphenicol O-Acetyltransferase / Q000235:genetics; D003593:Cytoplasm / Q000276:immunology / Q000821:virology; D017931:DNA Primers; D016325:HIV Long Terminal Repeat; D015497:HIV-1 / Q000502:physiology*; D006358:Hot Temperature; D006801:Humans; D008561:Membrane Fusion; D008969:Molecular Sequence Data; D010835:Phytohemagglutinins; D015398:Signal Transduction; D013601:T-Lymphocytes / Q000821:virology*; D014158:Transcription, Genetic; D014779:Virus Replication
D015704:CD4 Antigens; D016827:CD8 Antigens; D017931:DNA Primers; D010835:Phytohemagglutinins; D015500:Chloramphenicol O-Acetyltransferase