Copine-I represses NF-kappaB transcription by endoproteolysis of p65.
Nuclear factor-kappaB (NF-kappaB) is a dynamic transcription factor that regulates important biological processes involved in cancer initiation and progression. Identifying regulators that control the half-life of NF-kappaB is important to understanding molecular processes that control the duration of transcriptional responses. In this study we identify copine-I, a calcium phospholipid-binding protein, as a novel repressor that physically interacts with p65 to inhibit NF-kappaB transcription. Knockdown of copine-I by siRNA increases tumor necrosis factor alpha-stimulated NF-kappaB transcription, while copine-I expression blocks endogenous transcription. Copine-I abolishes NF-kappaB transcription by inducing endoprotease processing of the N-terminus of p65, a process antagonized by IkappaB alpha. Copine-I stimulates endoproteolysis of p65 within a conserved region that is required for base-specific contact with DNA. p65 proteins lacking the N-terminus fail to bind to DNA and act as dominant-negative molecules that inhibit NF-kappaB transcription. Our work provides evidence that copine-I regulates the half-life of NF-kappaB transcriptional responses through a novel mechanism that involves endoproteolysis of the p65 protein.
Ramsey
C S
CS
Department of Biochemistry and Molecular Genetics, University of Virginia, Charlottesville, VA 22908, USA.
Yeung
F
F
Stoddard
P B
PB
Li
D
D
Creutz
C E
CE
Mayo
M W
MW
D002352:Carrier Proteins / Q000737:chemistry* / Q000494:pharmacology; D002460:Cell Line; D045744:Cell Line, Tumor; D004247:DNA / Q000737:chemistry; D005786:Gene Expression Regulation; D006801:Humans; D008297:Male; D008954:Models, Biological; D016328:NF-kappa B / Q000378:metabolism*; D010743:Phospholipids / Q000737:chemistry; D011471:Prostatic Neoplasms / Q000378:metabolism; D017434:Protein Structure, Tertiary; D034741:RNA, Small Interfering / Q000378:metabolism; D050863:Synaptotagmin I / Q000378:metabolism*; D014158:Transcription, Genetic
D002352:Carrier Proteins; D016328:NF-kappa B; D010743:Phospholipids; D034741:RNA, Small Interfering; D050863:Synaptotagmin I; C110203:copine; D004247:DNA