Repression of the Id2 (inhibitor of differentiation) gene promoter during exit from the cell cycle.
The Id2 gene is one of several "Id-like" genes which encode helix-loop-helix proteins which dimerize with basic helix-loop-helix proteins and inhibit binding to the DNA enhancer element known as an E box. By repressing the DNA binding activity of basic helix-loop-helix proteins, Id proteins inhibit transcription of tissue-specific genes in myoblasts, hematopoietic precursor cells, and other types of undifferentiated cells. Serum starvation results in the disappearance of Id gene transcripts in most types of cultured cells, and often induces differentiation of these cells. In order to gain some insight into this process, we have analyzed Id2 promoter function in the glioma cell line U87Y. We have isolated 300 base pairs of Id2 promoter sequence which is sufficient to repress the activity of a reporter gene in serum-starved U87Y cells, but induces the activity of the reporter gene when the cells are stimulated with fresh serum. Two regions within this 300 base pair sequence contain repressor elements; deletion of either region results in increased promoter activity. Both repressor regions serve as binding sites for a protein present in extracts from serum-starved U87Y cells but not in serum-stimulated cells.
Biggs
J R
JR
Department of Neurological Surgery, School of Medicine, University of California, San Francisco 94143, USA.
Zhang
Y
Y
Murphy
E V
EV
D000595:Amino Acid Sequence; D001483:Base Sequence; D001790:Blood Physiological Phenomena; D002453:Cell Cycle / Q000502:physiology*; D004268:DNA-Binding Proteins / Q000235:genetics*; D017353:Gene Deletion; D018257:Helix-Loop-Helix Motifs; D051798:Inhibitor of Differentiation Protein 1; D008969:Molecular Sequence Data; D009457:Neuroglia / Q000166:cytology; D011401:Promoter Regions, Genetic; D012333:RNA, Messenger / Q000378:metabolism; D012097:Repressor Proteins; D014157:Transcription Factors; D014162:Transfection; D014407:Tumor Cells, Cultured
D004268:DNA-Binding Proteins; D051798:Inhibitor of Differentiation Protein 1; D012333:RNA, Messenger; D012097:Repressor Proteins; D014157:Transcription Factors