Mn. Uittenbogaard et al., TRANSCRIPTIONAL REPRESSION OF P53 BY HUMAN T-CELL LEUKEMIA-VIRUS TYPE-I TAX PROTEIN, The Journal of biological chemistry, 270(48), 1995, pp. 28503-28506
The human T-cell leukemia virus type I oncoprotein Tax transcriptional
ly deregulates a wide variety of viral and cellular genes. Tax deregul
ation of gene expression is mediated through interaction with a variet
y of structurally unrelated cellular transcription factors, as Tax doe
s not bind DNA in a sequence-specific manner. Although most of these c
ellular transcription factors have been shown to mediate activation by
Tax, we have recently demonstrated that members of the basic helix-lo
op-helix (bHLH) family of transcription factors, which play a critical
role in progression through the cell cycle, mediate repression by Tax
. In this report, we examined whether Tax might repress transcription
of the tumor suppressor p53, as the p53 gene has recently been demonst
rated to be regulated by the bHLH protein c-Myc. Furthermore, loss or
inactivation of the p53 gene has been shown to be causally associated
with oncogenic transformation. We show that Tax represses transcriptio
n of the p53 gene and that this repression is dependent upon the bHLH
recognition element in the p53 promoter. Together, these results sugge
st that Tax may promote malignant transformation through repression of
p53 transcription.