Lactation status influences expression of CCAAT/enhancer binding protein isoform mRNA in the mouse mammary gland

✍ Scribed by Andrew P. Gigliotti; James W. DeWille

• Publisher: John Wiley and Sons
• Year: 1998
• Tongue: English
• Weight: 515 KB
• Volume: 174
• Category: Article
• ISSN: 0021-9541
• DOI: 10.1002/(sici)1097-4652(199802)174:2<232::aid-jcp10>3.0.co;2-e

✦ Synopsis

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/EBPa, b, and d 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-a mRNA is detectable at low levels during pregnancy and postlactational involution. C/EBP-b mRNA levels are elevated during pregnancy, decline slightly in midlactation, and are induced within 48 hours of the onset of involution. C/EBP-d mRNA content is low throughout pregnancy and lactation, but increases dramatically (ú100-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-d mRNA during involution. In contrast to mammary gland, C/EBP-a is the predominate isoform expressed in liver with relatively low expression of C/EBP-b and C/EBP-d 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-d and C/EBP-b during postlactational involution is consistent with a role for C/EBPs in the regulation of mammary epithelial cell apoptosis.