Repression of activator protein-1-mediated transcriptional activation by the Notch-1 intracellular domain.
Developmental decisions that control cell fate are commonly regulated by the Notch signaling pathway. Activation of transmembrane Notch receptors results in proteolytic liberation of the intracellular domain of Notch, which translocates into the nucleus, binds a repressor (C promoter binding factor 1/RBP-Jkappa, Su(H), and Lag-1 (CSL)), and induces target genes. We found that the intracellular domain of human Notch-1 (NIC-1) represses activator protein-1 (AP-1)-mediated transactivation. Because numerous genes that control immune and inflammatory responses are AP-1-dependent and Notch regulates immune cell function, we investigated the underlying molecular mechanisms. Repression of AP-1 by NIC-1 did not represent a general inhibitory effect on transcription because nuclear factor kappaB-dependent transcription and transcription driven by a constitutive promoter and enhancer were not affected by NIC-1. The physiological relevance of the repression was supported by the facts that repression was apparent in multiple cell lines, endogenous AP-1 target genes were repressed, and similar concentrations of NIC-1 were required for CSL-dependent activation and AP-1 repression. The RBP-Jkappa-associated molecule domain of NIC-1 that mediates CSL binding and distinct sequences necessary for transactivation were required for repression. However, there was not a strict correlation between the sequence requirements for CSL-dependent activation and AP-1 repression. Repression correlated with predominant nuclear localization of NIC-1 and was not accompanied by disruption of c-Jun amino-terminal kinase-dependent signaling events required for AP-1 activation or by defective AP-1 DNA binding activity. These results provide evidence for negative cross-talk between Notch and AP-1, which may have important consequences for controlling diverse biological processes.
Chu
Jianlin
J
Department of Pharmacology, Molecular and Cellular Pharmacology Program, University of Wisconsin Medical School, 387 Medical Sciences Center, 1300 University Ave., Madison, WI 53706, USA.
Jeffries
Shawn
S
Norton
Jason E
JE
Capobianco
Anthony J
AJ
Bresnick
Emery H
EH
D000595:Amino Acid Sequence; D000818:Animals; D015152:Blotting, Northern; D002460:Cell Line; D002467:Cell Nucleus / Q000378:metabolism; D004305:Dose-Response Relationship, Drug; D019084:Fluorescent Antibody Technique, Indirect; D005786:Gene Expression Regulation; D006367:HeLa Cells; D006801:Humans; D048031:JNK Mitogen-Activated Protein Kinases; D020014:K562 Cells; D008565:Membrane Proteins / Q000737:chemistry* / Q000378:metabolism; D051379:Mice; D020928:Mitogen-Activated Protein Kinases / Q000737:chemistry; D008969:Molecular Sequence Data; D010957:Plasmids / Q000378:metabolism; D011485:Protein Binding; D017434:Protein Structure, Tertiary; D021381:Protein Transport; D051881:Receptor, Notch1; D011956:Receptors, Cell Surface; D012190:Retroviridae / Q000235:genetics; D017386:Sequence Homology, Amino Acid; D013997:Time Factors; D018808:Transcription Factor AP-1 / Q000737:chemistry / Q000378:metabolism*; D014157:Transcription Factors; D015533:Transcriptional Activation; D014162:Transfection
D008565:Membrane Proteins; C497761:NOTCH1 protein, human; C497762:Notch1 protein, mouse; D051881:Receptor, Notch1; D011956:Receptors, Cell Surface; D018808:Transcription Factor AP-1; D014157:Transcription Factors; D048031:JNK Mitogen-Activated Protein Kinases; D020928:Mitogen-Activated Protein Kinases