SHP-2 Phosphatase Regulates DNA Damage-induced Apoptosis and G2/M Arrest in Catalytically Dependent and Independent Manners, Respectively

Liangping Yuan,Wen-Mei Yu,Min Xu,Cheng-Kui Qu

doi:10.1074/jbc.m506768200

Liangping Yuan, Wen-Mei Yu + Show 2 more

Open Access

https://doi.org/10.1074/jbc.m506768200

Copy DOI

Abstract

SHP-2, a tyrosine phosphatase implicated in diverse signaling pathways induced by growth factors and cytokines, is also involved in DNA damage-triggered signaling and cellular responses. We previously demonstrated that SHP-2 played an important role in DNA damage-induced apoptosis and G2/M cell cycle checkpoint. In the present studies, we have provided evidence that SHP-2 functions in DNA damage apoptosis and G2/M arrest in catalytically dependent and independent manners, respectively. Mutant embryonic fibroblasts with the Exon 3 deletion mutation in SHP-2 showed decreased apoptosis and diminished G2/M arrest in response to cisplatin treatment. Wild type (WT), but not catalytically inactive mutant SHP-2 (SHP-2 C459S), rescued the apoptotic response of the mutant cells. Interestingly, both WT and SHP-2 C459S efficiently restored the G2/M arrest response. Furthermore, inhibition of the catalytic activity of endogenous SHP-2 in WT cells by overexpression of SHP-2 C459S greatly decreased cell death but not G2/M arrest induced by cisplatin. Biochemical analyses revealed that activation of c-Abl kinase was decreased in SHP-2 C459S-overexpressing cells. However, DNA damage-induced translocation of Cdc25C from the nucleus to the cytoplasm was fully restored in both WT and SHP-2 C459S "rescued" cells. Additionally, we demonstrated that the role of SHP-2 in DNA damage-induced cellular responses was independent of the tumor suppressor p53. Embryonic stem cells with the SHP-2 deletion mutation showed markedly decreased sensitivity to cisplatin-induced apoptosis, attributed to impaired induction of p73 but not p53. In agreement with these results, DNA damage-induced apoptosis and G2/M arrest were also decreased in SHP-2/p53 double mutant embryonic fibroblasts. Collectively, these studies have further defined the mechanisms by which SHP-2 phosphatase regulates DNA damage responses.

Highlights

Components of the p53-independent pathway are mediated by p73 (8 –10), a newly identified member of the p53 transcription factor family [11, 12]
Differential Roles of the Catalytic Activity of SHP-2 Phosphatase in DNA Damage-induced Apoptosis and G2/M Arrest—SHP-2 is a protein phosphatase, possessing a catalytic activity; previous studies have shown that in growth factor/cytokine signaling pathways, SHP-2 functions as an adaptor protein independent of its enzymatic activity (27, 40 – 42)
To address whether the catalytic activity of SHP-2 is required for its role in DNA damage-triggered signaling and cellular responses, we took advantage of the mutant embryonic fibroblast cell lines with a loss-of-function deletion mutation in SHP-2 (SHP-2⌬/⌬), which have been shown by our previous studies to be defective in DNA damage-induced apoptosis and G2/M arrest [31, 32]

Summary

Introduction

Components of the p53-independent pathway are mediated by p73 (8 –10), a newly identified member of the p53 transcription factor family [11, 12]. SHP-2 enhances cellular apoptotic response to DNA damage by promotion of the activation of nuclear kinase c-Abl. We have shown that SHP-2 is involved in the DNA damage-induced cell cycle checkpoint.

Results

Conclusion