The p68 and p72 DEAD box RNA helicases interact with HDAC1 and repress transcription in a promoter-specific manner

In this report we show that p68 and p72 can, in some contexts, act as transcriptional repressors. Targeting of p68 or p72 to constitutive promoters leads to repression of transcription; this repression is promoter-specific. Moreover both p68 and p72 associate with histone deacetylase 1 (HDAC1), a well-established transcriptional repression protein.It is therefore clear that p68 and p72 are important transcriptional regulators, functioning as co-activators and/or co-repressors depending on the context of the promoter and the transcriptional complex in which they exist.The DEAD/H box family of RNA helicases has been demonstrated to be involved in virtually all processes that require manipulation of RNA including transcription, pre-mRNA and pre-rRNA processing, RNA export, ribosome assembly and translation [1]. Although, in vitro, several members of this family have been shown to unwind RNA duplexes, relatively few appear to be true processive helicases and it is clear that, in the cell, many are likely to be involved in unwinding of short base paired regions of RNA or in the modulation of RNA-protein interactions.DNA helicases belong to a superfamily of proteins that is distantly related to DEAD/H box RNA helicases and includes the Werner syndrome protein (WRN) [2] and the Xeroderma pigmentosum XPB and XPD proteins [3], which have well established roles in transcription. Although the functions of DEAD/H box RNA helicases in other cellular processes, such as pre-mRNA processing and translation have been well studied, their role in transcriptional regulation is only now emerging. Examples of DEAD/H box RNA helicases involved in transcription include RNA helicase II (RHII/Gu) and RNA helicase A (RHA/NDHII). RHII/Gu was demonstrated to be a cofactor for c-Jun-activated transcription [4] and was shown to translocate from the nucleolus to the nucleoplasm after UV or anisomycin treatment (which activates JNK signalling). Although RHII/Gu was found to associate with phosphory