title: HIV-1 Tat interactions with p300 and PCAF transcriptional coactivators inhibit histone acetylation and neurotrophin signaling through CREB.
abstract: The human immunodeficiency virus type-1 (HIV-1) infects microglia, macrophages, and astrocytes in the central nervous system (CNS) and may cause severe neurological diseases, such as AIDS-related dementias or progressive encephalopathies, as a result of CNS inflammation and neurotrophin signaling defects associated with expression of viral antigens and HIV-1 replication in the brain. The HIV Tat protein can be endocytosed by surrounding uninfected cells; interacts with transcriptional coactivators/acetyltransferases, p300/CREB-binding protein, and p300/CREB-binding protein-associated factor (PCAF); and induces neuronal apoptosis. Since nerve growth factor (NGF) receptor and brain-derived neurotrophic factor receptor signaling through CREB requires p300 and PCAF histone acetyltransferases, we sought to determine whether HIV-1 Tat coactivator interactions interfere with neurotrophin receptor signaling in neuronal cells. Here, we demonstrate that Tat-coactivator interactions inhibit NGF- and brain-derived neurotrophic factor-responsive CRE trans-activation and neurotrophin protection against apoptosis in PC12 and IMR-32 neuroblastoma cells. Purified recombinant Tat or Tat-derived synthetic peptides, spanning p300- and PCAF-binding sequences, inhibit histone H3/H4 acetylation in vitro. A Tat mutant, TatK28A/K50A, defective for binding p300 and PCAF, neither repressed NGF-responsive CRE transactivation nor inhibited histone acetylation. HIV-1 Tat interacts in PCAF complexes in post-mortem CNS tissues from donor neuro-AIDS patients, as determined by fluorescence resonance energy transfer immunoconfocal microscopy. Importantly, these findings suggest that HIV-1 Tat-coactivator interactions may contribute to neurotrophin signaling impairments and neuronal apoptosis associated with HIV-1 infections of the CNS.
authors.affiliation: Laboratory of Molecular Virology, Department of Biological Sciences, Southern Methodist University, Dallas, Texas 75275-0376, USA.
authors.forename: Kasuen
authors.initials: K
authors.lastname: Wong
authors.forename: Anima
authors.initials: A
authors.lastname: Sharma
authors.forename: Soumya
authors.initials: S
authors.lastname: Awasthi
authors.forename: Elizabeth F
authors.initials: EF
authors.lastname: Matlock
authors.forename: Lowery
authors.initials: L
authors.lastname: Rogers
authors.forename: Carine
authors.initials: C
authors.lastname: Van Lint
authors.forename: Daniel J
authors.initials: DJ
authors.lastname: Skiest
authors.forename: Dennis K
authors.initials: DK
authors.lastname: Burns
authors.forename: Robert
authors.initials: R
authors.lastname: Harrod
mesh_terms: D000107:Acetylation; D000123:Acetyltransferases / Q000378:metabolism*; D000595:Amino Acid Sequence; D000818:Animals; D018797:Cell Cycle Proteins / Q000378:metabolism*; D045744:Cell Line, Tumor; D017362:Cyclic AMP Response Element-Binding Protein / Q000502:physiology*; D031541:Fluorescence Resonance Energy Transfer; D015696:Gene Products, tat / Q000378:metabolism*; D015497:HIV-1 / Q000502:physiology; D051548:Histone Acetyltransferases; D006657:Histones / Q000378:metabolism*; D006801:Humans; D018613:Microscopy, Confocal; D008969:Molecular Sequence Data; D009414:Nerve Growth Factors / Q000502:physiology*; D009447:Neuroblastoma; D016716:PC12 Cells; D010673:Pheochromocytoma; D051381:Rats; D011993:Recombinant Fusion Proteins / Q000302:isolation & purification / Q000378:metabolism; D015398:Signal Transduction; D014157:Transcription Factors / Q000378:metabolism*; D014162:Transfection; D014779:Virus Replication; D050880:p300-CBP Transcription Factors; D054322:tat Gene Products, Human Immunodeficiency Virus; D000099224:p300-CBP-Associated Factor
chemical_list: D000123:Acetyltransferases; D018797:Cell Cycle Proteins; D017362:Cyclic AMP Response Element-Binding Protein; D015696:Gene Products, tat; D051548:Histone Acetyltransferases; D006657:Histones; D009414:Nerve Growth Factors; D011993:Recombinant Fusion Proteins; D014157:Transcription Factors; D050880:p300-CBP Transcription Factors; D054322:tat Gene Products, Human Immunodeficiency Virus; D000099224:p300-CBP-Associated Factor