Target selectivity of vertebrate notch proteins. Collaboration between discrete domains and CSL-binding site architecture determines activation probability.
All four mammalian Notch proteins interact with a single DNA-binding protein (RBP-jkappa), yet they are not equivalent in activating target genes. Parallel assays of three Notch-responsive promoters in several cell lines revealed that relative activation strength is dependent on protein module and promoter context more than the cellular context. Each Notch protein reads binding site orientation and distribution on the promoter differently; Notch1 performs extremely well on paired sites, and Notch3 prefers single sites in conjunction with a proximal zinc finger transcription factor. Although head-head sites can elicit a Notch response on their own, use of CBS (CSL binding site) in tail-tail orientation is context-dependent. Bias for specific DNA elements is achieved by interplay between the N-terminal RAM (RBP-jkappa-associated molecule/ankyrin region), which interprets CBS proximity and orientation, and the C-terminal transactivation domain that interacts specifically with the transcription machinery or nearby factors. To confirm the prediction that modular design underscores the evolution of functional divergence between Notch proteins, we generated a synthetic Notch protein (Notch1 ankyrin with Notch3 transactivation domain) that displayed superior signaling strength on the hes5 promoter. Consistent with the prediction that "preferred" targets (Hes1) should respond faster and at lower Notch concentration than other targets, we showed that Hes5-GFP was extinguished fast and recovered slowly, whereas Hes1-GFP was inhibited late and recovered quickly after a pulse of DAPT in metanephroi cultures.
Ong
Chin-Tong
CT
Department of Molecular Biology and Pharmacology, Division of Dermatology, Washington University School of Medicine, St. Louis, Missouri 63110, USA.
Cheng
Hui-Teng
HT
Chang
Li-Wei
LW
Ohtsuka
Toshiyuki
T
Kageyama
Ryoichiro
R
Stormo
Gary D
GD
Kopan
Raphael
R
D000818:Animals; D001483:Base Sequence; D051792:Basic Helix-Loop-Helix Proteins / Q000737:chemistry; D001665:Binding Sites; D015153:Blotting, Western; D002460:Cell Line; D045744:Cell Line, Tumor; D004247:DNA / Q000737:chemistry; D004305:Dose-Response Relationship, Drug; D005260:Female; D017353:Gene Deletion; D049452:Green Fluorescent Proteins / Q000737:chemistry / Q000378:metabolism; D006367:HeLa Cells; D018398:Homeodomain Proteins / Q000737:chemistry; D006801:Humans; D007150:Immunohistochemistry; D007700:Kinetics; D008156:Luciferases / Q000378:metabolism; D008297:Male; D051379:Mice; D008954:Models, Biological; D008957:Models, Genetic; D015233:Models, Statistical; D008969:Molecular Sequence Data; D041681:NIH 3T3 Cells; D009924:Organ Culture Techniques; D011401:Promoter Regions, Genetic; D011485:Protein Binding; D017434:Protein Structure, Tertiary; D051880:Receptors, Notch / Q000378:metabolism*; D012097:Repressor Proteins / Q000737:chemistry; D013997:Time Factors; D000072056:Transcription Factor HES-1; D014157:Transcription Factors / Q000378:metabolism; D014158:Transcription, Genetic; D015533:Transcriptional Activation; D014162:Transfection
D051792:Basic Helix-Loop-Helix Proteins; D004247:DNA; D049452:Green Fluorescent Proteins; D018398:Homeodomain Proteins; D008156:Luciferases; D051880:Receptors, Notch; D012097:Repressor Proteins; D000072056:Transcription Factor HES-1; D014157:Transcription Factors; C489734:Hes1 protein, mouse; C489685:Hes5 protein, mouse; C077478:HES5 protein, human; C078493:HES1 protein, human