p53 and NF-κB are key transcription factors in regulating the gene expression program of cellular and organismal senescence. PPM1B is a member of the protein phosphatase 2C family and plays a role in negatively regulating p53 and NF-κB thereby possibly attenuating the gene expression program of cellular senescence. Here, possible involvement of PPM1B in replicative senescence has been investigated using the in vitro aging model of IMR-90 cells. PPM1B protein levels are progressively decreased in a replicative age-dependent manner. Importantly, PPM1B depletion induces a robust senescence phenotype as evidenced by significant growth arrest and senescence marker expression. Given that PPM1B depletion-induced senescence is partially rescued by inactivating p38 MAPK, our results identify PPM1B as a critical regulator of both p38 MAPK-dependent and independent senescence pathways during normal cellular aging process.
Keywords: Cellular senescence; MAPK; PP2C; PPM1B; p38; p53.
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