Doctor of Philosophy, The Ohio State University, 2004, Veterinary Biosciences
Human T-lymphotropic virus type-1 (HTLV-1), a deltaretrovirus cause adult T-cell leukemia/lymphoma and other lymphocyte-mediated disorders. HTLV-1 provirus encodes various regulatory and accessory genes, including p30(II). Our laboratory has identified the functional properties of pX ORF-II encoded p30(II), but the role of this viral protein in virus replication or pathogenesis remains unclear. We have reported that HTLV-1 p30(II), a nuclear-localizing protein, interacts with CBP/p300, disrupts CREB-Tax-CBP/p300 complex formation at HTLV-1 Tax-Responsive Elements repeats (TRE) and differentially modulates CREB and TRE-mediated transcription. We have also recently demonstrated that p30(II) is critical in maintaining viral loads in vivo. Herein, we further characterized the role of p30(II) in regulation of cellular gene expression, using microarrays and identified alterations of interrelated pathways of cell-proliferation, T-cell signaling, apoptosis and cell-cycle in p30(II)-expressing T-lymphocytes. We are the first to test the overall effect of an HTLV-1 accessory protein, on cellular gene expression and demonstrate that p30(II) activates transcription factors involved in T-cell signaling/activation, such as NFAT, NF-KB and AP-1. We further characterized the role of p30(II) in regulation of viral gene expression, by identifying motifs critical in binding p300 and regulating TRE-mediated transcription. By analysing the amino acid domain of p30(II) critical for repressing LTR-mediated transcription, we identified a lysine residue at amino acid 106 of p30(II), that is critical for repressing TRE-mediated transcription. Additionally, we found that p300 reverses p30(II)-dependent repression of TRE-mediated transcription, in a dose-responsive manner. Our data confirms the role of p30(II) as a regulator of viral gene transcription, in association with p300. However, unlike wildtype p300, p300 HAT mutants only partially rescue p30(II)-mediated LTR repression. Additionally, (open full item for complete abstract)
Committee: Michael Lairmore (Advisor)
Subjects: Biology, Molecular