title: CD28 ligation in the absence of TCR promotes RelA/NF-kappaB recruitment and trans-activation of the HIV-1 LTR.
abstract: CD28 is one of the most important co-stimulatory receptors necessary for full T lymphocyte activation. CD28 can act as a TCR-independent signalling unit by delivering specific signals which may induce HIV transcription and replication. However, the mechanisms by which CD28 regulates HIV expression remain largely unknown. Here we show that the TCR-independent CD28 signals lead to the trans-activation of HIV-1 LTR in an NF-kappaB-dependent manner. In particular, we found that CD28 engagement by B7 induces the specific recruitment of RelA/NF-kappaB subunit to the HIV-1 LTR promoter both in vitro and in ex vivo infected cells. The results obtained by mutating specific tyrosine residues within the CD28 cytoplasmic tail as well as by using LY294002 inhibitory drug evidenced that the recruitment and activation of the phosphatidylinositol 3-kinase/Akt signalling pathway is crucial in mediating CD28-induced HIV transcription through RelA/NF-kappaB.
authors.affiliation: Department of Cellular and Developmental Biology, Sapienza University of Rome, Rome, Italy.
authors.forename: Alessandro
authors.initials: A
authors.lastname: Annibaldi
authors.forename: Angela
authors.initials: A
authors.lastname: Sajeva
authors.forename: Michela
authors.initials: M
authors.lastname: Muscolini
authors.forename: Fabiola
authors.initials: F
authors.lastname: Ciccosanti
authors.forename: Marco
authors.initials: M
authors.lastname: Corazzari
authors.forename: Mauro
authors.initials: M
authors.lastname: Piacentini
authors.forename: Loretta
authors.initials: L
authors.lastname: Tuosto
mesh_terms: D019943:Amino Acid Substitution; D018122:B7-1 Antigen / Q000494:pharmacology; D018106:CD28 Antigens / Q000378:metabolism*; D002467:Cell Nucleus / Q000378:metabolism; D002867:Chromones / Q000494:pharmacology; D004791:Enzyme Inhibitors / Q000494:pharmacology; D015870:Gene Expression / Q000187:drug effects; D015967:Gene Expression Regulation, Viral; D016325:HIV Long Terminal Repeat / Q000235:genetics*; D006801:Humans; D019169:Jurkat Cells; D007976:Leupeptins / Q000494:pharmacology; D009025:Morpholines / Q000494:pharmacology; D016328:NF-kappa B / Q000378:metabolism*; D050778:NFATC Transcription Factors / Q000378:metabolism; D019869:Phosphatidylinositol 3-Kinases / Q000502:physiology; D000081082:Phosphoinositide-3 Kinase Inhibitors; D021381:Protein Transport / Q000187:drug effects; D051057:Proto-Oncogene Proteins c-akt / Q000502:physiology; D011948:Receptors, Antigen, T-Cell / Q000378:metabolism; D018808:Transcription Factor AP-1 / Q000378:metabolism; D051996:Transcription Factor RelA / Q000235:genetics / Q000378:metabolism*; D015533:Transcriptional Activation / Q000187:drug effects; D014162:Transfection
chemical_list: D018122:B7-1 Antigen; D018106:CD28 Antigens; D002867:Chromones; D004791:Enzyme Inhibitors; D007976:Leupeptins; D009025:Morpholines; D016328:NF-kappa B; D050778:NFATC Transcription Factors; D019869:Phosphatidylinositol 3-Kinases; D000081082:Phosphoinositide-3 Kinase Inhibitors; D051057:Proto-Oncogene Proteins c-akt; D011948:Receptors, Antigen, T-Cell; D018808:Transcription Factor AP-1; D051996:Transcription Factor RelA; C498143:RELA protein, human; C085911:2-(4-morpholinyl)-8-phenyl-4H-1-benzopyran-4-one; C072553:benzyloxycarbonylleucyl-leucyl-leucine aldehyde