A human protein with sequence similarity to Drosophila mastermind coordinates the nuclear form of notch and a CSL protein to build a transcriptional activator complex on target promoters.
Mastermind (Mam) has been implicated as an important positive regulator of the Notch signaling pathway by genetic studies using Drosophila melanogaster. Here we describe a biochemical mechanism of action of Mam within the Notch signaling pathway. Expression of a human sequence related to Drosophila Mam (hMam-1) in mammalian cells augments induction of Hairy Enhancer of split (HES) promoters by Notch signaling. hMam-1 stabilizes and participates in the DNA binding complex of the intracellular domain of human Notch1 and a CSL protein. Truncated versions of hMam-1 that can maintain an association with the complex behave in a dominant negative fashion and depress transactivation. Furthermore, Drosophila Mam forms a similar complex with the intracellular domain of Drosophila Notch and Drosophila CSL protein during activation of Enhancer of split, the Drosophila counterpart of HES. These results indicate that Mam is an essential component of the transcriptional apparatus of Notch signaling.
Kitagawa
M
M
Department of Molecular and Tumor Pathology, Chiba University Graduate School of Medicine, Chuo-ku, Chiba 260-8670, Japan. kitagawa@med.m.chiba-u.ac.jp
Oyama
T
T
Kawashima
T
T
Yedvobnick
B
B
Kumar
A
A
Matsuno
K
K
Harigaya
K
K
D000595:Amino Acid Sequence; D000818:Animals; D002460:Cell Line; D004268:DNA-Binding Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D029721:Drosophila Proteins; D004331:Drosophila melanogaster / Q000235:genetics; D005786:Gene Expression Regulation; D006801:Humans; D019476:Insect Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D046911:Macromolecular Substances; D008562:Membrane Glycoproteins; D008565:Membrane Proteins / Q000235:genetics / Q000378:metabolism*; D008856:Microscopy, Fluorescence; D008969:Molecular Sequence Data; D009687:Nuclear Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D011401:Promoter Regions, Genetic; D017434:Protein Structure, Tertiary; D011956:Receptors, Cell Surface / Q000235:genetics / Q000378:metabolism; D051880:Receptors, Notch; D016415:Sequence Alignment; D015398:Signal Transduction; D015534:Trans-Activators; D014157:Transcription Factors; D015533:Transcriptional Activation; D014162:Transfection
C423451:CSL receptor, human; D004268:DNA-Binding Proteins; D029721:Drosophila Proteins; D019476:Insect Proteins; C430872:MAML1 protein, human; D046911:Macromolecular Substances; D008562:Membrane Glycoproteins; D008565:Membrane Proteins; C497759:N protein, Drosophila; D009687:Nuclear Proteins; D011956:Receptors, Cell Surface; D051880:Receptors, Notch; D015534:Trans-Activators; D014157:Transcription Factors; C085316:mam protein, Drosophila