The levels of p53 govern the hierarchy of DNA damage tolerance pathway usage

Abstract

It is well-established that, through canonical functions in transcription and DNA repair, the tumor suppressor p53 plays a central role in safeguarding cells from the consequences of DNA damage. Recent data retrieved in tumor and stem cells demonstrated that p53 also carries out non-canonical functions when interacting with the translesion synthesis (TLS) polymerase iota (POLι) at DNA replication forks. This protein complex triggers a DNA damage tolerance (DDT) mechanism controlling the DNA replication rate. Given that the levels of p53 trigger non-binary rheostat-like functions in response to stress or during differentiation, we explore the relevance of the p53 levels for its DDT functions at the fork. We show that subtle changes in p53 levels modulate the contribution of some DDT factors including POLι, POLη, POLζ, REV1, PCNA, PRIMPOL, HLTF and ZRANB3 to the DNA replication rate. Our results suggest that the levels of p53 are central to coordinate the balance between DDT pathways including (i) fork-deceleration by the ZRANB3-mediated fork reversal factor, (ii) POLι-p53-mediated fork-slowing, (iii) POLι- and POLη-mediated TLS and (iv) PRIMPOL-mediated fork-acceleration. Collectively, our study reveals the relevance of p53 protein levels for the DDT pathway choice in replicating cells.

BMP signaling promotes heart regeneration via alleviation of replication stress

“…In addition, our DNA fiber spreading assays in cultured human cells indicate that BMP signaling can promote replication fork re-start, which also appears to represent a different function than the p53-dependent cell cycle exit observed by Li and colleagues 55 . However, more recent works have carved out non-canonical roles of p53 at DNA replication barriers in safeguarding the correct choice of the bypass mechanism depending on the p53 level, cell type and differentiation status [58][59][60] . Future work will be necessary to clarify to which extent the different ways in which BMP signaling impinges on genomic stress are celltype and context-specific.…”

“…The DNA fiber spreading assay was performed as described before [58][59][60] . In brief, cells were labeled with 20 mM 5-chloro-2-deoxyuridine (CldU, Sigma-Aldrich by Merck, Darmstadt, Germany) for 20 min, then washed with pre-warmed PBS, followed by a second labelling with 200 mM 5-iodo-2-deoxyuridine (IdU, Sigma-Aldrich).…”