Human T-cell leukemia retrovirus-Tax protein is a repressor of nuclear receptor signaling

The Tax oncoprotein promotes cellular transformation and is associated with the pathogenesis of adult T-cell leukemia. Tay expression activates transc ription via the cAMP enhancer binding protein/activating transcription fact or (CREB/ATF) and NF kappa B pathways. In contrast to its positive action, here ne demonstrate that Tax is a potent repressor of steroid and retinoid receptor transcription. The Tax protein becomes localized in the promyelocy tic (PML) oncogenic domain, and unexpectedly, expression of the PML protein reverses Tax-induced repression. These results suggest that PML and Tax ma y act in opposing manners to influence nuclear receptor transcription and h uman T cell leukemia retrovirus pathogenesis.