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

J Cell Physiol. 1998 Feb;174(2):232-9. doi: 10.1002/(SICI)1097-4652(199802)174:2<232::AID-JCP10>3.0.CO;2-E.


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.

Publication types

  • Research Support, U.S. Gov't, P.H.S.

MeSH terms

  • Animals
  • CCAAT-Enhancer-Binding Proteins
  • DNA-Binding Proteins / biosynthesis
  • DNA-Binding Proteins / genetics*
  • Female
  • In Situ Hybridization
  • Lactation*
  • Mammary Glands, Animal / physiology*
  • Mice
  • Nuclear Proteins / biosynthesis
  • Nuclear Proteins / genetics*
  • Pregnancy
  • RNA, Messenger / biosynthesis
  • RNA, Messenger / genetics*


  • CCAAT-Enhancer-Binding Proteins
  • DNA-Binding Proteins
  • Nuclear Proteins
  • RNA, Messenger