Gigliotti A P, DeWille J W
Department of Veterinary Biosciences, The Ohio State University, Columbus 43210, USA.
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.
CCAAT/增强子结合蛋白（C/EBPs）是一类高度保守的DNA结合蛋白家族，参与多种组织中细胞生长和分化相关基因的转录调控。通过Northern印迹法和原位杂交技术，研究了正常小鼠乳腺在妊娠、泌乳和退化过程中C/EBP-α、β和δ mRNA的表达情况。乳腺C/EBP-α mRNA在妊娠期间和泌乳后退化过程中可检测到低水平表达。C/EBP-β mRNA水平在妊娠期间升高，在泌乳中期略有下降，并在退化开始后48小时内被诱导。C/EBP-δ mRNA含量在整个妊娠和泌乳期间较低，但在泌乳后退化开始后12小时内急剧增加（>100倍）。原位杂交表明，乳腺上皮细胞在退化过程中负责C/EBP-δ mRNA的表达。与乳腺不同，C/EBP-α是肝脏中表达的主要异构体，C/EBP-β和C/EBP-δ mRNA的表达相对较低。肝脏C/EBP异构体mRNA水平不受泌乳状态的影响。这些结果表明了C/EBPs的组织特异性调控。泌乳后退化过程中C/EBP-δ和C/EBP-β的明显顺序诱导与C/EBPs在乳腺上皮细胞凋亡调控中的作用一致。
