title: Possible role of subunit A of nuclear factor Y (NF-YA) in normal human diploid fibroblasts during senescence.
abstract: NF-Y, a heterotrimeric CCAAT binding protein, may have a role in regulating some G1/S genes whose expressions are attenuated during replicative senescence [Matuoka and Chen (1999) Exp Cell Res 253: 365-371]. The hallmark of replicative senescence is the loss of dividing potential. Hence, attenuation of G1/S gene expressions may be causally related to aging. To understand how NF-Y is involved in regulating G1/S genes during replicative senescence, we have examined the expressions of three NF-Y subunit genes in human IMR-90 cells over the entire course of their life-span. The mRNA levels of NF-YA, B, and C did not show any age-dependent change. In contrast, the protein level of NF-YA exhibited a significant and progressive decrease during cell senescence. Cross-linking experiments indicated that NF-Y may interact with proteins such as GCN5 and P/CAF. Co-transfection of cells with plasmid encoding NF-YA protein enhanced the expression of reporter gene fused with G1/S gene promoter that contains NF-Y sites. In contrast, co-transfection with plasmid encoding the dominant negative NF-YA mutant suppressed the expression of the reporter genes. Transient transfection of human cells with dominant negative NF-YA mutant could lead to an increase in neutral beta-galactosidase activity, a marker of cell senescence. These results support the view that NF-Y may have a role in cell senescence.
authors.affiliation: Department of Biochemistry, Institute of Medical Sciences, University of Tokyo, Tokyo, Japan.
authors.forename: K
authors.initials: K
authors.lastname: Matuoka
authors.forename: K Y
authors.initials: KY
authors.lastname: Chen
mesh_terms: D000123:Acetyltransferases / Q000378:metabolism; D023081:CCAAT-Binding Factor / Q000235:genetics / Q000378:metabolism / Q000502:physiology*; D018797:Cell Cycle Proteins / Q000378:metabolism; D002460:Cell Line; D016922:Cellular Senescence / Q000502:physiology*; D004268:DNA-Binding Proteins / Q000378:metabolism; D005347:Fibroblasts / Q000166:cytology; D006367:HeLa Cells; D051548:Histone Acetyltransferases; D006801:Humans; D009687:Nuclear Proteins / Q000235:genetics / Q000378:metabolism / Q000502:physiology*; D015534:Trans-Activators / Q000378:metabolism; D014157:Transcription Factors / Q000235:genetics / Q000378:metabolism / Q000502:physiology*; D015533:Transcriptional Activation; D050880:p300-CBP Transcription Factors; D000099224:p300-CBP-Associated Factor
chemical_list: D000123:Acetyltransferases; D023081:CCAAT-Binding Factor; D018797:Cell Cycle Proteins; D004268:DNA-Binding Proteins; D051548:Histone Acetyltransferases; D009687:Nuclear Proteins; D015534:Trans-Activators; D014157:Transcription Factors; D050880:p300-CBP Transcription Factors; D000099224:p300-CBP-Associated Factor; C492061:NFYA protein, human; C492063:NFYB protein, human; C501179:KAT2A protein, human