Nuclear deadenylation/polyadenylation factors regulate 3′ processing in response to DNA damage

Abstract

We previously showed that mRNA 3 0 end cleavage reaction in cell extracts is strongly but transiently inhibited under DNA-damaging conditions. The cleavage stimulation factor-50 (CstF-50) has a role in this response, providing a link between transcription-coupled RNA processing and DNA repair. In this study, we show that CstF-50 interacts with nuclear poly(A)-specific ribonuclease (PARN) using in vitro and in extracts of UV-exposed cells. The CstF-50/ PARN complex formation has a role in the inhibition of 3 0 cleavage and activation of deadenylation upon DNA damage. Extending these results, we found that the tumour suppressor BARD1, which is involved in the UV-induced inhibition of 3 0 cleavage, strongly activates deadenylation by PARN in the presence of CstF-50, and that CstF-50/ BARD1 can revert the cap-binding protein-80 (CBP80)-mediated inhibition of PARN activity. We also provide evidence that PARN along with the CstF/BARD1 complex participates in the regulation of endogenous transcripts under DNA-damaging conditions. We speculate that the interplay between polyadenylation, deadenylation and tumour-suppressor factors might prevent the expression of prematurely terminated messengers, contributing to control of gene expression under different cellular conditions.

To polyadenylate or to deadenylate

“…Studies have shown that deadenylases localize both in the nucleus and the cytoplasm and are involved in different cellular processes inhibition of mRNA 3' cleavage and activation of deadenylation upon DNA damage. Importantly, the tumor suppressor BARD1 also plays a role in the activation of deadenylation by PARN, 49 suggesting that the activation of deadenylation and the inhibition of 3' mRNA cleavage are part of the same cellular response to DNA damage. Interestingly, the cap binding protein 80 (CBP80) also binds PARN inhibiting its deadenylase activity in untreated cells, 52 representing a possible mechanism by which PARN is recruited to the nascent pre-mRNA and ensuring that PARN does not degrade the poly(A) tail of pre-mRNAs.…”

“…For example, CstF1 can also interact with PARN upon UV treatment. 49 Based on the nature of the factors, it is possible to hypothesize that the PARN/CstF1 interaction might regulate mRNA turnover in different cellular responses. Consistent with this, the CstF1/PARN complex plays a role in deadenylation machineries has been described in the DDR in mammalian cells (Fig.…”

“…1B). 49 In this case, it is possible that the nuclear polyadenylation/deadenylation machineries might signal the degradation of prematurely terminated and erroneously processed transcripts, which could be generated by the arrest and degradation of RNAP II at sites of DNA damage. This process might represent a mechanism of nuclear mRNA decay that avoids the formation of potentially deleterious hazardous proteins.…”

“…61 It is also low in non-stress conditions. 49,53,54 Then these short lived mRNAs increase transiently upon DNA damaging conditions and are involved in control of cell growth and differentiation. [55][56][57] Supporting the role of PARN deadenylase in DDR, other deadenylases have also been functionally connected with factors involved in the DDR in yeast.…”

“…Extending those studies, it was also shown that PARN along with CstF1/BARD1 complex participate in the regulation of endogenous transcripts during the DDR either by inhibition of 3' cleavage or by activation of deadenylation. 49 Interestingly, nuclear PARN also plays a role decreasing the stability of ARE-containing mRNAs, such as c-myc, c-fos and c-jun, and keeping their levels Model for cytoplasmic polyadenylation/deadenylation during cell differentiation processes. (a) the deadenylation and polyadenylation of dormant mrNas are controlled by cis-elements at 3'Utr, such as the CPe and the aaUaaa signals, which are recognized by the polyadenylation factors CPeB and CPSF, respectively.…”