title: Sumoylation of LAP1 is involved in the HDAC4-mediated repression of COX-2 transcription.
abstract: CEBPB, one of the CEBP family members, is a crucial regulator of gene expression during innate immunity, inflammatory responses and adipogenesis. In this study, the EGF-induced increase of CEBPB mRNA is shown to be coincident with the decrease of COX-2 mRNA. We identified that all of the individual CEBPB isoforms, LAP1, LAP2 and LIP, attenuate EGF-induced COX-2 promoter activity. Although increased sumoylation of both LAP1 and LAP2 is observed during the lagging stage of EGF treatment, only the sumoylated LAP1, but not the sumoylated LAP2, is responsible for COX-2 gene repression. In addition, EGF treatment can regulate the nucleocytoplasmic redistribution of HDAC4 and SUMO1. We further demonstrated by loss-of- and gain-of-function approaches that HDAC4 can be a negative regulator while inactivating COX-2 transcription. The sumoylation mutant LAP1, LAP1K174A, exhibits an attenuated ability to interact with HDAC4, and increased COX-2 promoter activity. Furthermore, the in vivo DNA binding assay demonstrated that LAP1K174A and CEBPDK120A, sumoylation-defective CEBPD mutants, attenuate the binding of HDAC4 on the COX-2 promoter. In light of the above, our data suggest that the suCEBPD and suLAP1 are involved in the repression of COX-2 transcription through the recruitment of HDAC4.
authors.affiliation: Institute of Basic Medical Sciences, National Cheng Kung University, Tainan, Taiwan.
authors.forename: Wen-Ling
authors.initials: WL
authors.lastname: Wang
authors.forename: Yi-Chao
authors.initials: YC
authors.lastname: Lee
authors.forename: Wen-Ming
authors.initials: WM
authors.lastname: Yang
authors.forename: Wen-Chang
authors.initials: WC
authors.lastname: Chang
authors.forename: Ju-Ming
authors.initials: JM
authors.lastname: Wang
mesh_terms: D001665:Binding Sites; D022782:CCAAT-Enhancer-Binding Protein-beta / Q000096:biosynthesis / Q000235:genetics / Q000378:metabolism*; D045744:Cell Line, Tumor; D051546:Cyclooxygenase 2 / Q000096:biosynthesis / Q000235:genetics*; D004815:Epidermal Growth Factor / Q000494:pharmacology; D020868:Gene Silencing; D006655:Histone Deacetylases / Q000378:metabolism*; D006801:Humans; D009154:Mutation; D011401:Promoter Regions, Genetic; D020033:Protein Isoforms / Q000378:metabolism; D012097:Repressor Proteins / Q000096:biosynthesis / Q000235:genetics / Q000378:metabolism*; D020218:Response Elements; D025841:Small Ubiquitin-Related Modifier Proteins / Q000378:metabolism*; D014158:Transcription, Genetic
chemical_list: D022782:CCAAT-Enhancer-Binding Protein-beta; D020033:Protein Isoforms; D012097:Repressor Proteins; D025841:Small Ubiquitin-Related Modifier Proteins; D004815:Epidermal Growth Factor; D051546:Cyclooxygenase 2; C400300:HDAC4 protein, human; D006655:Histone Deacetylases