Transcriptional regulation of C/EBP delta in G(0) growth-arrested mouse mammary epithelial cells

Little is known about the control of cell cycle exit/G(0) entry, or the reg ulation of genes that are expressed during G(0). In this report we used pri mer extension analysis to demonstrate the high level of C/EBP delta mRNA ex pression in G(0) growth-arrested HC11 mouse mammary epithelial cells and to identify the C/EBP delta transcription start site. The C/EBP delta gene tr anscription rate and promoter activity are both highly induced in G(0) grow th-arrested HC11 cells. The C/EBP delta gene promoter also exhibits G(0)-sp ecific autoregulation. In contrast, the C/EBP delta promoter activity decre ases in G(0) growth-arrested NIH 3T3 cells. These data indicate that C/EBP delta is among a relatively small number of genes actively transcribed duri ng G(0) growth arrest. C/EBP delta may regulate the expression of genes imp licated in the initiation or maintenance of mammary epithelial cell G(0) gr owth arrest. (C) 1999 Academic Press.