Soluble HIV-1 gp120 enhances HIV-1 replication in non-dividing CD4+ T cells, mediated via cell signaling and Tat cofactor overexpression.
OBJECTIVE
The soluble HIV-1 gp120 envelope glycoprotein, after being shed from infected cells, can cross-link its receptors on both HIV-1 infected and non-infected target cells, leading to their activation. We have assessed the impact of soluble gp120 on viral replication in CD4+/CXCR4+ T cells, via its effects on Tat-mediated transactivation of the HIV-1/LTR.


METHODS
Primary cord blood-derived CD4+/CXCR4+ T cells were stimulated with soluble recombinant gp120 (rgp120) from the HIV-1/HXB2 clone. The level of gene or protein expression was assessed by serial analysis gene expression (SAGE), reverse transcriptase-polymerase chain reaction, western blotting or flow-cytometry analysis. Cellular division of rgp120-stimulated T cells was assessed by CFDA-SE labeling. Long terminal repeat (LTR) activity and HIV infection level were respectively measured by a chemiluminescent beta-gal Reporter Gene Assay and by p24 determination.


RESULTS
We have demonstrated that rgp120 activates both PKCepsilon and its upstream effector PI3K/Akt, involved in the HIV-1 replication process. Moreover, rgp120 enhances the gene, as well as protein expression of the cellular Tat cofactors Tat-Sf1 and SPT5 in primary CD4+/CXCR4+ T cells. Finally, stimulation of HIV-1 infected T cells with rgp120 was found to result in both a higher LTR-activity and an increased production of viral particles.


CONCLUSIONS
Taken together, these results show that soluble gp120 contributes to HIV-1 replication and dissemination, via the activation of multiple cell signaling pathways and the induction of Tat-cofactor expression, underscoring its potential as a therapeutic target in HIV-1-mediated pathogenesis.
Missé
Dorothée
D
Institut de Recherche pour le Développement (IRD), UR34 Maladies Virales Emergentes, Laboratoire d'Immunologie Rétrovirale et Moléculaire; 240, Av. Emile Jeanbrau, EFS, 34094 Montpellier, France.
Gajardo
Johanna
J
Oblet
Christelle
C
Religa
Agniezska
A
Riquet
Nathalie
N
Mathieu
Danièle
D
Yssel
Hans
H
Veas
Francisco
F
D015496:CD4-Positive T-Lymphocytes / Q000276:immunology / Q000378:metabolism / Q000821:virology*; D002455:Cell Division / Q000187:drug effects; D002478:Cells, Cultured; D005786:Gene Expression Regulation / Q000187:drug effects / Q000276:immunology; D015696:Gene Products, tat / Q000378:metabolism*; D015699:HIV Envelope Protein gp120 / Q000494:pharmacology*; D016325:HIV Long Terminal Repeat / Q000276:immunology; D015497:HIV-1 / Q000502:physiology*; D006801:Humans; D008213:Lymphocyte Activation / Q000187:drug effects; D019718:Receptors, CXCR4 / Q000378:metabolism; D011994:Recombinant Proteins / Q000494:pharmacology; D020133:Reverse Transcriptase Polymerase Chain Reaction / Q000379:methods; D015398:Signal Transduction / Q000276:immunology; D012995:Solubility; D015533:Transcriptional Activation / Q000187:drug effects; D014779:Virus Replication / Q000187:drug effects* / Q000276:immunology; D054322:tat Gene Products, Human Immunodeficiency Virus
D015696:Gene Products, tat; D015699:HIV Envelope Protein gp120; D019718:Receptors, CXCR4; D011994:Recombinant Proteins; D054322:tat Gene Products, Human Immunodeficiency Virus