Requirement for down-regulation of the CCAAT-binding activity of the NF-Y transcription factor during skeletal muscle differentiation.
NF-Y is composed of three subunits, NF-YA, NF-YB, and NF-YC, all required for DNA binding. All subunits are expressed in proliferating skeletal muscle cells, whereas NF-YA alone is undetectable in terminally differentiated cells in vitro. By immunohistochemistry, we show that the NF-YA protein is not expressed in the nuclei of skeletal and cardiac muscle cells in vivo. By chromatin immunoprecipitation experiments, we demonstrate herein that NF-Y does not bind to the CCAAT boxes of target promoters in differentiated muscle cells. Consistent with this, the activity of these promoters is down-regulated in differentiated muscle cells. Finally, forced expression of the NF-YA protein in cells committed to differentiate leads to an impairment in the down-regulation of cyclin A, cyclin B1, and cdk1 expression and is accompanied by a delay in myogenin expression. Thus, our results indicate that the suppression of NF-Y function is of crucial importance for the inhibition of several cell cycle genes and the induction of the early muscle-specific program in postmitotic muscle cells.
Gurtner
Aymone
A
Molecular Oncogenesis Laboratory, Experimental Oncology Department, Regina Elena Cancer Institute, Rome, Italy.
Manni
Isabella
I
Fuschi
Paola
P
Mantovani
Roberto
R
Guadagni
Fiorella
F
Sacchi
Ada
A
Piaggio
Giulia
G
D000818:Animals; D023081:CCAAT-Binding Factor / Q000378:metabolism*; D002453:Cell Cycle; D002454:Cell Differentiation; D002467:Cell Nucleus / Q000378:metabolism; D002478:Cells, Cultured; D019925:Cyclin A / Q000378:metabolism; D019926:Cyclin B / Q000378:metabolism; D018844:Cyclin-Dependent Kinases / Q000378:metabolism; D015536:Down-Regulation; D005786:Gene Expression Regulation; D051379:Mice; D018485:Muscle Fibers, Skeletal / Q000166:cytology / Q000378:metabolism*; D018482:Muscle, Skeletal / Q000378:metabolism*; D011401:Promoter Regions, Genetic; D021122:Protein Subunits / Q000378:metabolism
D023081:CCAAT-Binding Factor; D019925:Cyclin A; D019926:Cyclin B; D021122:Protein Subunits; D018844:Cyclin-Dependent Kinases