Revelation of p53-independent Function of MTA1 in DNA Damage Response via Modulation of the p21WAF1-Proliferating Cell Nuclear Antigen Pathway

Da-Qiang Li,Suresh B Pakala,Sirigiri Divijendra Natha Reddy,Kazufumi Ohshiro,Shao-Hua Peng,Yi Lian,Sidney W Fu,Rakesh Kumar

doi:10.1074/jbc.m109.079095

Da-Qiang Li, Suresh B Pakala + Show 6 more

Open Access

https://doi.org/10.1074/jbc.m109.079095

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Abstract

Although metastasis-associated protein 1 (MTA1), a component of the nucleosome remodeling and deacetylase (NuRD) complex, is a DNA-damage response protein and regulates p53-dependent DNA repair, it remains unknown whether MTA1 also participates in p53-independent DNA damage response. Here, we provide evidence that MTA1 is a p53-independent transcriptional corepressor of p21(WAF1), and the underlying mechanism involves recruitment of MTA1-histone deacetylase 2 (HDAC2) complexes onto two selective regions of the p21(WAF1) promoter. Accordingly, MTA1 depletion, despite its effect on p53 down-regulation, superinduces p21(WAF1), increases p21(WAF1) binding to proliferating cell nuclear antigen (PCNA), and decreases the nuclear accumulation of PCNA in response to ionizing radiation. In support of a p53-independent role of MTA1 in DNA damage response, we further demonstrate that induced expression of MTA1 in p53-null cells inhibits p21(WAF1) promoter activity and p21(WAF1) binding to PCNA. Consequently, MTA1 expression in p53-null cells results in increased induction of gamma H2AX foci and DNA double strand break repair, and decreased DNA damage sensitivity following ionizing radiation treatment. These findings uncover a new target of MTA1 and the existence of an additional p53-independent role of MTA1 in DNA damage response, at least in part, by modulating the p21(WAF1)-PCNA pathway, and thus, linking two previously unconnected NuRD complex and DNA-damage response pathways.

Highlights

During the course of the gene profiling study in identifying transcriptome differences between the MTA1ϩ/ϩ and MTA1Ϫ/Ϫ mouse embryonic fibroblasts (MEFs), we found that p21WAF1 was up-regulated in the MTA1Ϫ/Ϫ MEFs relative to its wild-type controls despite the fact that the p53 protein was down-regulated in the MTA1Ϫ/Ϫ MEFs as compared with the MTA1ϩ/ϩ controls [11]
To further characterize the potential mechanism for the functional role of metastasis-associated protein 1 (MTA1) in DNA repair, we wished to identify the transcriptome differences between the MTA1ϩ/ϩ and MTA1Ϫ/Ϫ MEFs using Affymetrix mouse exon 1.0 ST GeneChips
Concomitant with higher p21WAF1 protein expression in the MTA1Ϫ/Ϫ MEFs relative to the MTA1ϩ/ϩ controls (Fig. 2A), p21WAF1 mRNA expression levels were increased significantly in the MTA1Ϫ/Ϫ MEFs compared with the MTA1ϩ/ϩ controls (Fig. 2B), indicating that MTA1 modulates p21WAF1 expression through, at least in part, transcriptional regulation

Summary

Introduction

MTA1 Is a Transcriptional Corepressor of p21WAF1 and Recruits MTA1-HDAC2 Complex onto the p21WAF1 Promoter— To further validate the above observations, we first examined the expression levels of the p21WAF1 protein in MTA1ϩ/ϩ and MTA1Ϫ/Ϫ MEFs by Western blot analysis, and found a distinct up-regulation of p21WAF1 protein in the MTA1Ϫ/Ϫ MEFs com- We found that p21WAF1-promoter luciferase activity was significantly higher in the MTA1Ϫ/Ϫ MEFs than that in the MTA1ϩ/ϩ controls (Fig. 2C), suggesting a potential co-repressor function of MTA1 on the p21WAF1 promoter.

Results

Conclusion