title: Role for KAP1 serine 824 phosphorylation and sumoylation/desumoylation switch in regulating KAP1-mediated transcriptional repression.
abstract: As a multifunctional protein, KRAB domain-associated protein 1 (KAP1) is reportedly subjected to multiple protein posttranslational modifications, including phosphorylation and sumoylation. However, gaps exist in our knowledge of how KAP1 phosphorylation cross-talks with KAP1 sumoylation and what the biological consequence is. Here, we show that doxorubicin (Dox) treatment induces KAP1 phosphorylation at Ser-824 via an ataxia telangiectasia mutated (ATM)-dependent manner, correlating with the transcriptional de-repression of p21WAF1/CIP1 and Gadd45alpha. A S824A substitution of KAP1, which ablates the ATM-induced phosphorylation, results in an increase of KAP1 sumoylation and repression of p21 transcription in Dox-treated cells. By contrast, a S824D mutation of KAP1, which mimics constitutive phosphorylation of KAP1, leads to a decrease of KAP1 sumoylation and stimulation of p21 transcription before the exposure of Dox. We further provide evidence that SENP1 deSUMOylase is involved in activating basal, but not Dox-induced, KAP1 Ser-824 phosphorylation, rendering a stimulation of p21 and Gadd45alpha transcription. Moreover, KAP1 and differential sumoylation of KAP1 were also demonstrated to fine-tune the transcription of three additional KAP1-targeted genes, including Bax, Puma, and Noxa. Taken together, our results suggest a novel role for ATM that selectively stimulates KAP1 Ser-824 phosphorylation to repress its sumoylation, leading to the de-repression of expression of a subset of genes involved in promoting cell cycle control and apoptosis in response to genotoxic stresses.
authors.affiliation: Department of Molecular and Clinical Pharmacology, City of Hope, Duarte, California 91010, USA.
authors.forename: Xu
authors.initials: X
authors.lastname: Li
authors.forename: Yung-Kang
authors.initials: YK
authors.lastname: Lee
authors.forename: Jen-Chong
authors.initials: JC
authors.lastname: Jeng
authors.forename: Yun
authors.initials: Y
authors.lastname: Yen
authors.forename: David C
authors.initials: DC
authors.lastname: Schultz
authors.forename: Hsiu-Ming
authors.initials: HM
authors.lastname: Shih
authors.forename: David K
authors.initials: DK
authors.lastname: Ann
mesh_terms: D000903:Antibiotics, Antineoplastic / Q000494:pharmacology; D017209:Apoptosis / Q000187:drug effects / Q000502:physiology; D051017:Apoptosis Regulatory Proteins / Q000096:biosynthesis / Q000235:genetics; D064007:Ataxia Telangiectasia Mutated Proteins; D002453:Cell Cycle / Q000187:drug effects / Q000502:physiology; D018797:Cell Cycle Proteins / Q000235:genetics / Q000378:metabolism*; D002460:Cell Line; D050759:Cyclin-Dependent Kinase Inhibitor p21 / Q000235:genetics / Q000378:metabolism; D003546:Cysteine Endopeptidases; D004249:DNA Damage / Q000187:drug effects / Q000502:physiology; D004268:DNA-Binding Proteins / Q000235:genetics / Q000378:metabolism*; D004317:Doxorubicin / Q000494:pharmacology; D010450:Endopeptidases / Q000235:genetics / Q000378:metabolism; D006801:Humans; D020125:Mutation, Missense; D009687:Nuclear Proteins / Q000235:genetics / Q000378:metabolism; D010766:Phosphorylation / Q000187:drug effects; D017346:Protein Serine-Threonine Kinases / Q000235:genetics / Q000378:metabolism*; D011518:Proto-Oncogene Proteins / Q000096:biosynthesis / Q000235:genetics; D019253:Proto-Oncogene Proteins c-bcl-2 / Q000096:biosynthesis / Q000235:genetics; D012097:Repressor Proteins / Q000235:genetics / Q000378:metabolism*; D025842:SUMO-1 Protein / Q000235:genetics / Q000378:metabolism*; D012694:Serine / Q000235:genetics / Q000378:metabolism; D014158:Transcription, Genetic / Q000187:drug effects / Q000502:physiology*; D000076183:Tripartite Motif-Containing Protein 28; D025521:Tumor Suppressor Proteins / Q000235:genetics / Q000378:metabolism*; D051028:bcl-2-Associated X Protein / Q000096:biosynthesis / Q000235:genetics; D000097642:GADD45 Proteins
chemical_list: D000903:Antibiotics, Antineoplastic; D051017:Apoptosis Regulatory Proteins; D064007:Ataxia Telangiectasia Mutated Proteins; D018797:Cell Cycle Proteins; D050759:Cyclin-Dependent Kinase Inhibitor p21; D003546:Cysteine Endopeptidases; D004268:DNA-Binding Proteins; D004317:Doxorubicin; D010450:Endopeptidases; D009687:Nuclear Proteins; D017346:Protein Serine-Threonine Kinases; D011518:Proto-Oncogene Proteins; D019253:Proto-Oncogene Proteins c-bcl-2; D012097:Repressor Proteins; D025842:SUMO-1 Protein; D012694:Serine; D000076183:Tripartite Motif-Containing Protein 28; D025521:Tumor Suppressor Proteins; D051028:bcl-2-Associated X Protein; C494826:BAX protein, human; C438378:BBC3 protein, human; C493956:CDKN1A protein, human; C439070:GADD45A protein, human; D000097642:GADD45 Proteins; C498702:PMAIP1 protein, human; C101116:TRIM28 protein, human; C576324:ATM protein, human; C404512:SENP1 protein, human