Cip29 is phosphorylated following activation of the DNA damage response in Xenopus egg extracts.

Janet Holden,Elaine M Taylor,Howard D Lindsay,Sue Cotterill

doi:10.1371/journal.pone.0181131

Abstract

Acting through a complex signalling network, DNA lesions trigger a range of cellular responses including DNA repair, cell cycle arrest, altered gene expression and cell death, which help to limit the mutagenic effects of such DNA damage. RNA processing factors are increasingly being recognised as important targets of DNA damage signalling, with roles in the regulation of gene expression and also more directly in the promotion of DNA repair. In this study, we have used a Xenopus laevis egg extract system to analyse the DNA damage-dependent phosphorylation of a putative RNA export factor, Cip29. We have found that Cip29 is rapidly phosphorylated in response to DNA double-strand breaks in this experimental system. We show that the DNA damage-inducible modification of Cip29 is dependent on the activity of the key double-strand break response kinase, ATM, and we have identified a conserved serine residue as a damage-dependent phosphorylation site. Finally, we have determined that Cip29 is not required for efficient DNA end-joining in egg extracts. Taken together, these data identify Cip29 as a novel target of the DNA damage response and suggest that the damage-dependent modification of Cip29 may relate to a role in the regulation of gene expression after DNA damage.

Highlights

A hallmark of cancer, genome instability is recognised as a key driving force in cancer progression, since it facilitates the acquisition of further tumourigenic changes [1]
Principal amongst these is DNA damage signalling via the phosphatidylinositol 3-kinaselike kinases (PI3KK), ATM and ATR, which elicits a variety of cellular responses, including activation of DNA repair mechanisms, cell cycle arrest or apoptosis [4]
Western blotting confirmed that these antibodies recognise a single band of approximately 27kDa corresponding to the in vitro translated Cip29 protein while, in X. laevis egg extract, they recognise two bands of approximately 27 and 28kDa, as well as a non-specific band of approximately 43kDa (Fig 1A)

Summary

Introduction

A hallmark of cancer, genome instability is recognised as a key driving force in cancer progression, since it facilitates the acquisition of further tumourigenic changes [1]. A variety of DNA damage response (DDR) pathways exist to contend with such genetic damage Principal amongst these is DNA damage signalling via the phosphatidylinositol 3-kinaselike kinases (PI3KK), ATM (ataxia telangiectasia mutated) and ATR (ataxia telangiectasia and Rad related), which elicits a variety of cellular responses, including activation of DNA repair mechanisms, cell cycle arrest or apoptosis [4].

Methods

Results

Discussion

Conclusion