title: SOCS1 links cytokine signaling to p53 and senescence.
abstract: SOCS1 is lost in many human tumors, but its tumor suppression activities are not well understood. We report that SOCS1 is required for transcriptional activity, DNA binding, and serine 15 phosphorylation of p53 in the context of STAT5 signaling. In agreement, inactivation of SOCS1 disabled p53-dependent senescence in response to oncogenic STAT5A and radiation-induced apoptosis in T cells. In addition, SOCS1 was sufficient to induce p53-dependent senescence in fibroblasts. The mechanism of activation of p53 by SOCS1 involved a direct interaction between the SH2 domain of SOCS1 and the N-terminal transactivation domain of p53, while the C-terminal domain of SOCS1 containing the SOCS Box mediated interaction with the DNA damage-regulated kinases ATM/ATR. Also, SOCS1 colocalized with ATM at DNA damage foci induced by oncogenic STAT5A. Collectively, these results add another component to the p53 and DNA damage networks and reveal a mechanism by which SOCS1 functions as a tumor suppressor.
authors.affiliation: Département de Biochimie, Université de Montréal, Montréal, Québec H3C 3J7, Canada.
authors.forename: Viviane
authors.initials: V
authors.lastname: Calabrese
authors.forename: Frédérick A
authors.initials: FA
authors.lastname: Mallette
authors.forename: Xavier
authors.initials: X
authors.lastname: Deschênes-Simard
authors.forename: Sheela
authors.initials: S
authors.lastname: Ramanathan
authors.forename: Julien
authors.initials: J
authors.lastname: Gagnon
authors.forename: Adrian
authors.initials: A
authors.lastname: Moores
authors.forename: Subburaj
authors.initials: S
authors.lastname: Ilangumaran
authors.forename: Gerardo
authors.initials: G
authors.lastname: Ferbeyre
mesh_terms: D000818:Animals; D064007:Ataxia Telangiectasia Mutated Proteins; D018797:Cell Cycle Proteins / Q000378:metabolism; D045744:Cell Line, Tumor; D002467:Cell Nucleus / Q000378:metabolism; D016922:Cellular Senescence; D004249:DNA Damage; D004268:DNA-Binding Proteins / Q000378:metabolism; D006801:Humans; D051379:Mice; D010766:Phosphorylation; D017346:Protein Serine-Threonine Kinases / Q000378:metabolism; D034622:RNA Interference; D050799:STAT5 Transcription Factor / Q000378:metabolism; D015398:Signal Transduction; D000071222:Suppressor of Cytokine Signaling 1 Protein; D050826:Suppressor of Cytokine Signaling Proteins / Q000032:analysis / Q000378:metabolism / Q000502:physiology*; D016159:Tumor Suppressor Protein p53 / Q000378:metabolism*; D025521:Tumor Suppressor Proteins / Q000378:metabolism
chemical_list: D018797:Cell Cycle Proteins; D004268:DNA-Binding Proteins; C108944:SOCS1 protein, human; D050799:STAT5 Transcription Factor; D000071222:Suppressor of Cytokine Signaling 1 Protein; D050826:Suppressor of Cytokine Signaling Proteins; D016159:Tumor Suppressor Protein p53; D025521:Tumor Suppressor Proteins; C576324:ATM protein, human; C576597:ATR protein, human; D064007:Ataxia Telangiectasia Mutated Proteins; C576325:Atm protein, mouse; D017346:Protein Serine-Threonine Kinases