title: p38 Mitogen-activated protein kinase- and HuR-dependent stabilization of p21(Cip1) mRNA mediates the G(1)/S checkpoint.
abstract: Activation of p38 mitogen-activated protein kinase (MAPK) plays an important role in the G(2)/M cell cycle arrest induced by DNA damage, but little is known about the role of this signaling pathway in the G(1)/S transition. Upregulation of the cyclin-dependent kinase inhibitor p21(Cip1) is thought to make a major contribution to the G(1)/S cell cycle arrest induced by gamma radiation. We show here that inhibition of p38 MAPK impairs p21(Cip1) accumulation and, as a result, the ability of cells to arrest in G(1) in response to gamma radiation. We found that p38 MAPK induces p21(Cip1) mRNA stabilization, without affecting its transcription or the stability of the protein. In particular, p38 MAPK phosphorylates the mRNA binding protein HuR on Thr118, which results in cytoplasmic accumulation of HuR and its enhanced binding to the p21(Cip1) mRNA. Our findings help to understand the emerging role of p38 MAPK in the cellular responses to DNA damage and reveal the existence of p53-independent networks that cooperate in modulating p21(Cip1) levels at the G(1)/S checkpoint.
authors.affiliation: CNIO (Spanish National Cancer Center), Melchor Fernandez Almagro 3, 28029 Madrid, Spain.
authors.forename: Vanesa
authors.initials: V
authors.lastname: Lafarga
authors.forename: Ana
authors.initials: A
authors.lastname: Cuadrado
authors.forename: Isabel
authors.initials: I
authors.lastname: Lopez de Silanes
authors.forename: Rocio
authors.initials: R
authors.lastname: Bengoechea
authors.forename: Oscar
authors.initials: O
authors.lastname: Fernandez-Capetillo
authors.forename: Angel R
authors.initials: AR
authors.lastname: Nebreda
mesh_terms: D000818:Animals; D000954:Antigens, Surface / Q000235:genetics / Q000378:metabolism*; D064007:Ataxia Telangiectasia Mutated Proteins; D018797:Cell Cycle Proteins / Q000235:genetics / Q000378:metabolism; D002460:Cell Line / Q000502:physiology / Q000528:radiation effects; D050759:Cyclin-Dependent Kinase Inhibitor p21 / Q000235:genetics / Q000378:metabolism*; D004249:DNA Damage; D004268:DNA-Binding Proteins / Q000235:genetics / Q000378:metabolism; D051959:ELAV Proteins; D000067780:ELAV-Like Protein 1; D004789:Enzyme Activation; D016193:G1 Phase / Q000502:physiology*; D005720:Gamma Rays; D006801:Humans; D051379:Mice; D010766:Phosphorylation; D017346:Protein Serine-Threonine Kinases / Q000235:genetics / Q000378:metabolism; D020871:RNA Stability; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism*; D034741:RNA, Small Interfering / Q000235:genetics / Q000378:metabolism; D016601:RNA-Binding Proteins / Q000235:genetics / Q000378:metabolism*; D016196:S Phase / Q000502:physiology*; D016159:Tumor Suppressor Protein p53 / Q000235:genetics / Q000378:metabolism; D025521:Tumor Suppressor Proteins / Q000235:genetics / Q000378:metabolism; D048051:p38 Mitogen-Activated Protein Kinases / Q000235:genetics / Q000378:metabolism*
chemical_list: D000954:Antigens, Surface; D018797:Cell Cycle Proteins; D050759:Cyclin-Dependent Kinase Inhibitor p21; D004268:DNA-Binding Proteins; D051959:ELAV Proteins; D000067780:ELAV-Like Protein 1; C098770:ELAVL1 protein, human; D012333:RNA, Messenger; D034741:RNA, Small Interfering; D016601:RNA-Binding Proteins; D016159:Tumor Suppressor Protein p53; D025521:Tumor Suppressor Proteins; C576324:ATM protein, human; D064007:Ataxia Telangiectasia Mutated Proteins; C576325:Atm protein, mouse; D017346:Protein Serine-Threonine Kinases; D048051:p38 Mitogen-Activated Protein Kinases