Mechanism for the transcriptional repression by c-Myc on PDGF beta-receptor.
c-Myc plays a key role in the cell cycle dependent control of the PDGF beta-receptor mRNA. The mouse platelet-derived growth factor (PDGF) beta-receptor promoter contains a CCAAT motif, and NF-Y plays an essential role in its transcription. Coexpression of c-Myc represses PDGF beta-receptor luciferase reporter activity, and the CCAAT motif in the promoter is indispensable for this repression. Here we show that c-Myc binds NF-Y subunits, YB and YC, by immunoprecipitation from cotransfected COS-1 cells. The in vitro-translated c-Myc also binds the glutathione S-transferase (GST)-NF-YB fusion protein and GST-NF-YC, but not GST-NF-YA. The most C-terminal region of HAP domains of NF-YB and NF-YC, and the Myc homology boxes, but not the C-terminal bHLHZip domain, are indispensable for the coimmunoprecipitation, and also for the repression of PDGF beta-receptor. c-Myc binds NF-Y complex without affecting the efficiency of NF-Y binding to DNA. However, the expression of Myc represses the transcriptional activation of NF-YC when fused to the GAL4 DNA binding domain. Furthermore, this repression was seen only when Myc homology boxes are present, and NF-YC contains the c-Myc binding region.
Izumi
H
H
Department of Cell Biology, Institute of Anatomy and Cell Biology, Göteborg University, Box 420, SE-405 30, Gothenburg, Sweden.
Molander
C
C
Penn
L Z
LZ
Ishisaki
A
A
Kohno
K
K
Funa
K
K
D016475:3T3 Cells / Q000378:metabolism; D000818:Animals; D001943:Breast Neoplasms / Q000378:metabolism; D023081:CCAAT-Binding Factor / Q000737:chemistry / Q000378:metabolism*; D019556:COS Cells / Q000378:metabolism; D002352:Carrier Proteins / Q000737:chemistry / Q000378:metabolism; D004268:DNA-Binding Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D006801:Humans; D051379:Mice; D011401:Promoter Regions, Genetic / Q000235:genetics / Q000502:physiology; D017434:Protein Structure, Tertiary / Q000235:genetics / Q000502:physiology; D016271:Proto-Oncogene Proteins c-myc / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D020797:Receptor, Platelet-Derived Growth Factor beta / Q000037:antagonists & inhibitors* / Q000378:metabolism; D014158:Transcription, Genetic / Q000235:genetics / Q000502:physiology*; D015533:Transcriptional Activation / Q000502:physiology*; D014407:Tumor Cells, Cultured / Q000378:metabolism
D023081:CCAAT-Binding Factor; D002352:Carrier Proteins; D004268:DNA-Binding Proteins; D016271:Proto-Oncogene Proteins c-myc; D020797:Receptor, Platelet-Derived Growth Factor beta