Nucleophosmin Protein Dephosphorylation by DUSP3 Is a Fine-Tuning Regulator of p53 Signaling to Maintain Genomic Stability

Abstract

The dual-specificity phosphatase 3 (DUSP3), an atypical protein tyrosine phosphatase (PTP), regulates cell cycle checkpoints and DNA repair pathways under conditions of genotoxic stress. DUSP3 interacts with the nucleophosmin protein (NPM) in the cell nucleus after UV-radiation, implying a potential role for this interaction in mechanisms of genomic stability. Here, we show a high-affinity binding between DUSP3-NPM and NPM tyrosine phosphorylation after UV stress, which is increased in DUSP3 knockdown cells. Specific antibodies designed to the four phosphorylated NPM’s tyrosines revealed that DUSP3 dephosphorylates Y29, Y67, and Y271 after UV-radiation. DUSP3 knockdown causes early nucleolus exit of NPM and ARF proteins allowing them to disrupt the HDM2-p53 interaction in the nucleoplasm after UV-stress. The anticipated p53 release from proteasome degradation increased p53-Ser15 phosphorylation, prolonged p53 half-life, and enhanced p53 transcriptional activity. The regular dephosphorylation of NPM’s tyrosines by DUSP3 balances the p53 functioning and favors the repair of UV-promoted DNA lesions needed for the maintenance of genomic stability.

AML-Related NPM Mutations Drive p53 Delocalization into the Cytoplasm with Possible Impact on p53-Dependent Stress Response

“…In their work, silencing of dual-specificity phosphatase 3 (DUSP3) led to NPM dephosphorylation on tyrosines Y29, Y67 and Y217. Increased NPM monomer/oligomer ratio and enhanced p53-S15 phosphorylation has been observed as well [73]. Strong induction of p53 in Figure 11B accompanied by signs of lowered NPMmut level in the Selinexor-treated OCI-AML3 suggests that such large p53 increase could be related to the presence of NPMmut.…”

“…Selinexorinduced phosphorylation on several Serine residues responsible for p53 activation was also detected (Figure S6). Amplified p53 transcriptional activity in response to UVC radiation has been recently reported in cells with aberrantly phosphorylated NPM [73]. In their work, silencing of dual-specificity phosphatase 3 (DUSP3) led to NPM dephosphorylation on tyrosines Y29, Y67 and Y217.…”

DUSP3 regulates phosphorylation-mediated degradation of occludin and is required for maintaining epithelial tight junction

“…Suppression of DUSP3 has been shown to associate with attenuation of DNA repair ability [ 57 ]. Recent reports showing that knockdown of DUSP3 expression is associated with the hyperphosphorylation of a nucleoplasmin protein NPM and G2/M cell cycle arrest [ 58 , 59 ]. DUSP3 also appears to be an NPM phosphatase and regulates downstream HDM2-p53 interaction and genomic stability upon UV irradiation [ 58 ].…”

“…Recent reports showing that knockdown of DUSP3 expression is associated with the hyperphosphorylation of a nucleoplasmin protein NPM and G2/M cell cycle arrest [ 58 , 59 ]. DUSP3 also appears to be an NPM phosphatase and regulates downstream HDM2-p53 interaction and genomic stability upon UV irradiation [ 58 ]. Interestingly, we also observed DNA hyperploidy and hypoploidy of DUSP3-deficient cells in comparison to wild type cells (Additional file 1 : Fig.…”

The role of dual‐specificity phosphatase 3 in melanocytic oncogenesis

“…It was recently identified that DUSP3 dephosphorylates NPM by high‐affinity binding after induced UV stress 77,78 . Complementarily, p53 was found intensely phosphorylated and activated after UV exposure in the context of DUSP3 knockdown/silencing, as well as highly stabilized after cycloheximide‐induced stress, 78 indicating that DUSP3 balances p53 phosphorylation via its interaction with p53's regulators.…”