Involvement of HTLV-I Tax and CREB in aneuploidy: a bioinformatics approach.
BACKGROUND
Adult T-cell leukemia (ATL) is a complex and multifaceted disease associated with human T-cell leukemia virus type 1 (HTLV-I) infection. Tax, the viral oncoprotein, is considered a major contributor to cell cycle deregulation in HTLV-I transformed cells by either directly disrupting cellular factors (protein-protein interactions) or altering their transcription profile. Tax transactivates these cellular promoters by interacting with transcription factors such as CREB/ATF, NF-kappaB, and SRF. Therefore by examining which factors upregulate a particular set of promoters we may begin to understand how Tax orchestrates leukemia development.


RESULTS
We observed that CTLL cells stably expressing wild-type Tax (CTLL/WT) exhibited aneuploidy as compared to a Tax clone deficient for CREB transactivation (CTLL/703). To better understand the contribution of Tax transactivation through the CREB/ATF pathway to the aneuploid phenotype, we performed microarray analysis comparing CTLL/WT to CTLL/703 cells. Promoter analysis of altered genes revealed that a subset of these genes contain CREB/ATF consensus sequences. While these genes had diverse functions, smaller subsets of genes were found to be involved in G2/M phase regulation, in particular kinetochore assembly. Furthermore, we confirmed the presence of CREB, Tax and RNA Polymerase II at the p97Vcp and Sgt1 promoters in vivo through chromatin immunoprecipitation in CTLL/WT cells.


CONCLUSIONS
These results indicate that the development of aneuploidy in Tax-expressing cells may occur in response to an alteration in the transcription profile, in addition to direct protein interactions.
de la Fuente
Cynthia
C
The George Washington University Medical Center, Department of Biochemistry and Molecular Biology, Washington, DC 20037, USA. bcmclf@gwumc.edu
Gupta
Madhur V
MV
Klase
Zachary
Z
Strouss
Katharine
K
Cahan
Patrick
P
McCaffery
Timothy
T
Galante
Anthony
A
Soteropoulos
Patricia
P
Pumfery
Anne
A
Fujii
Masahiro
M
Kashanchi
Fatah
F
D000782:Aneuploidy; D001665:Binding Sites; D047369:Chromatin Immunoprecipitation; D019295:Computational Biology / Q000379:methods*; D017362:Cyclic AMP Response Element-Binding Protein / Q000235:genetics* / Q000378:metabolism; D004257:DNA Polymerase II / Q000235:genetics / Q000378:metabolism; D020869:Gene Expression Profiling / Q000379:methods; D005786:Gene Expression Regulation; D016356:Gene Products, tax / Q000096:biosynthesis / Q000235:genetics* / Q000378:metabolism; D016355:Genes, pX; D015368:Human T-lymphotropic virus 1 / Q000235:genetics; D006801:Humans; D018386:Kinetochores / Q000502:physiology; D015461:Leukemia, Prolymphocytic, T-Cell / Q000235:genetics / Q000821:virology; D020411:Oligonucleotide Array Sequence Analysis; D011401:Promoter Regions, Genetic; D013602:T-Lymphocytes, Cytotoxic / Q000378:metabolism / Q000502:physiology*; D014162:Transfection
C115163:CREB1 protein, human; D017362:Cyclic AMP Response Element-Binding Protein; D016356:Gene Products, tax; D004257:DNA Polymerase II