Gene Expression Array of HTLV Type 1-Infected T Cells: Up-regulation of Transcription Factors and Cell Cycle Genes

Abstract

By utilizing a human cDNA expression array blot (588 genes), we have observed overexpression of various transcription factors, cell cycle regulated kinases, and DNA repair genes in HTLV-1-infected T cells. One of the genes of interest, and focus in this study, is the cyclin-dependent kinase inhibitor, p21/waf1. The p21/waf1 transcription and protein is overexpressed in all HTLV-1-infected cell lines tested as well as ATL and HAM/TSP patient samples. While p21/waf1 has been shown to display a selectivity for G(1)/S cyclin/cdk complexes, we have observed p21/waf1 to be complexed with cyclin A/cdk2. Functionally, the association of p21/cyclin A/cdk2 decreased the histone H1 phosphorylation in vitro, as observed in immunoprecipitations followed by kinase assays, as well as affecting other substrates such as the C-terminus of Rb protein involved in c-Abl and HDAC1 regulation. Wild-type, but not a mutant form (M47) of Tax, was found to be able to transactivate the p21/waf1 promoter in a p53-independent manner. We found that the minimal p21/waf1 promoter (-49 to +49 sequence) was activated by Tax and the minimal promoter contained two E2A transcription factor binding sites located between the TATA box and the initiation site. E2A proteins, E12 and E47, as well as a related helix-loop-helix protein, HEB, are all up-regulated in HTLV-1-infected T cells. When using band shift analysis, we found that only the E1 site (overlapping the transcription start site) was a functional DNA binding site. By using a chromatin immunoprecipitation (ChIP) assay, we observed that histone H4, and not histone H3, was acetylated from the endogenous p21/waf1 promoter in vivo, implying that CBP/p300, and not the SAGA complex, was critical in complexing with E2A in up-regulation of p21/waf1 in HTLV-1-infected cells.

Highly Enhanced Expression of CD70 on Human T-Lymphotropic Virus Type 1-Carrying T-Cell Lines and Adult T-Cell Leukemia Cells

“…Human oligonucleotide microarrays have been used to examine gene expression patterns of PBMCs infected with HTLV-1 (11), HTLV-1-transformed T-cell lines (8,30), Jurkat cells expressing either p12I (26) or p30II (23), and the Jurkat cell line JPX-9 that can be induced to express higher levels of Tax-1 (27). In addition, activated PBMC cDNA has been used in subtraction hybridization studies with cDNA from cultured ATL cells from a patient (33).…”

HTLV-1 bZIP Factor HBZ Promotes Cell Proliferation and Genetic Instability by Activating OncomiRs

“…Genome-wide transcriptome reprogramming is a hallmark of HTLV-1 infection (5,8,9) that relies mainly on Tax and HBZ, two HTLV-1-encoded proteins that can hijack host transcription factors and chromatin modifiers to positively or negatively modulate cellular gene expression (10,11). The pleiotropic effects of Tax activity include cell proliferation, prevention of apoptosis, and promotion of genetic instability (12).…”

Gene expression profiling of ATL patients: compilation of disease-related genes and evidence for TCF4 involvement in BIRC5 gene expression and cell viability

“…Expression profiles of HTLV-1-infected cells and Taxexpressing cells grown in vitro have provided a list of HTLV-1/Taxregulated genes. [21][22][23][24] Many of these genes are involved in regulation of T-cell proliferation, such as IL-2, IL-2R␣ (allowing for an autocrine loop), IL-15, IL-15R, granulocyte-macrophage colonystimulating factor (GM-CSF), and tumor necrosis factor-␣ (TNF-␣). 1,2,25 As noted, however, the oncogenic features of HTLV-1-infected cells versus malignant cells from ATL patients have distinct phenotypes.…”