Lactation status influences expression of CCAAT/enhancer binding protein isoform mRNA in the mouse mammary gland.
The CCAAT/enhancer binding proteins (C/EBPs) are a highly conserved family of DNA binding proteins implicated in the transcriptional control of genes involved in cell growth and differentiation in a variety of tissues. The expression of C/EBP-alpha, beta, and delta mRNA in the normal mouse mammary gland was investigated during pregnancy, lactation, and involution via Northern blotting and in situ hybridization. Mammary gland C/EBP-alpha mRNA is detectable at low levels during pregnancy and postlactational involution. C/EBP-beta mRNA levels are elevated during pregnancy, decline slightly in midlactation, and are induced within 48 hours of the onset of involution. C/EBP-delta mRNA content is low throughout pregnancy and lactation, but increases dramatically (>100-fold) within 12 hours after the onset of postlactational involution. In situ hybridization demonstrates that mammary epithelial cells are responsible for the expression of C/EBP-delta mRNA during involution. In contrast to mammary gland, C/EBP-alpha is the predominate isoform expressed in liver with relatively low expression of C/EBP-beta and C/EBP-delta mRNA. Liver C/EBP isoform mRNA levels are unaffected by lactation status. These results demonstrate the tissue-specific regulation of C/EBPs. The pronounced sequential induction of C/EBP-delta and C/EBP-beta during postlactational involution is consistent with a role for C/EBPs in the regulation of mammary epithelial cell apoptosis.
Gigliotti
A P
AP
Department of Veterinary Biosciences, The Ohio State University, Columbus 43210, USA.
DeWille
J W
JW
D000818:Animals; D022762:CCAAT-Enhancer-Binding Proteins; D004268:DNA-Binding Proteins / Q000096:biosynthesis / Q000235:genetics*; D005260:Female; D017403:In Situ Hybridization; D007774:Lactation; D008321:Mammary Glands, Animal / Q000502:physiology*; D051379:Mice; D009687:Nuclear Proteins / Q000096:biosynthesis / Q000235:genetics*; D011247:Pregnancy; D012333:RNA, Messenger / Q000096:biosynthesis / Q000235:genetics*
D022762:CCAAT-Enhancer-Binding Proteins; D004268:DNA-Binding Proteins; D009687:Nuclear Proteins; D012333:RNA, Messenger