Cytomegalovirus and human herpesvirus-6 trans-activate the HIV-1 long terminal repeat via multiple response regions in human fetal astrocytes.
Cytomegalovirus (CMV) and human herpesvirus-6 (HHV-6) infection stimulated HIV-1 replication and trans-activated the HIV-1 promoter (the long terminal repeat or LTR) to a similar extent in transfected, nonimmortalized, human fetal astrocytes. CMV infection increased basal LTR expression by approximately sevenfold, while HHV-6 infection increased basal LTR expression by fourfold. This enhancing effect required cell-cell contact between CMV-infected or HHV-6-infected and LTR-containing cells. To determine the target regions on the HIV promoter that respond to CMV and HHV-6 trans-activation, several modified LTR-reporter gene constructs were tested. Loss of functional NFkappaB, Sp1, or upstream modulatory sites on the LTR caused significant reduction ofbasal LTR expression in astrocytes. These elements also mediated the trans-activation events during HHV-6 or CMV infection in astrocytes, though to varying degrees. Electrophoretic mobility shift assays (EMSA) indicated that core, enhancer, and upstream modulatory regions of the LTR interacted specifically with nuclear proteins from both uninfected and CMV- or HHV-6-infected human fetal astrocytes. CMV or HHV-6 infection did not appear to induce unique, LTR-specific nuclear binding proteins, but rather enhanced the relative proportion of some of the existing protein complexes, in particular, the complexes formed with the AP-1 binding sites on the HIV-1 LTR (nt - 354 to - 316). Our data suggest that CMV or HHV-6 trans-activation of HIV LTR activity in human fetal astrocytes proceeds via intracellular molecular interactions involving herpesviral gene products, cellular proteins, and multiple sites on the LTR upstream of the TATA box. The pattern of LTR activity in astrocytes suggests that host cell factors modulating HIV expression may differ from those dominant in T-cells or immortalized astroglia, and this could contribute to differences in the astrocyte's ability to support HIV replication.
McCarthy
M
M
Department of Veterans Affairs Medical Center, Miami, Florida 33125, USA.
Auger
D
D
He
J
J
Wood
C
C
D001253:Astrocytes / Q000378:metabolism / Q000821:virology*; D002478:Cells, Cultured; D003587:Cytomegalovirus / Q000502:physiology*; D015342:DNA Probes / Q000378:metabolism; D005333:Fetus; D017930:Genes, Reporter; D016655:HIV Core Protein p24 / Q000378:metabolism; D016325:HIV Long Terminal Repeat / Q000235:genetics*; D015497:HIV-1 / Q000235:genetics / Q000502:physiology*; D015654:Herpesvirus 6, Human / Q000502:physiology*; D006801:Humans; D009687:Nuclear Proteins / Q000378:metabolism; D016759:Oncogene Protein p65(gag-jun) / Q000276:immunology / Q000378:metabolism; D016761:Oncogene Proteins v-fos / Q000276:immunology / Q000378:metabolism; D020218:Response Elements / Q000235:genetics*; D017384:Sequence Deletion; D015533:Transcriptional Activation; D014162:Transfection
D015342:DNA Probes; D016655:HIV Core Protein p24; D009687:Nuclear Proteins; D016759:Oncogene Protein p65(gag-jun); D016761:Oncogene Proteins v-fos