Expression of Id and ITF-2 genes in the mammary gland during pregnancy.
Id-1 is one of the four related helix-loop-helix Id proteins that act as inhibitors of the basic helix-loop-helix (bHLH) transcription factors that control cell differentiation, development and carcinogenesis. We previously found that Id-1 regulated the growth, differentiation, apoptosis and invasion of mouse mammary epithelial cells in culture. Using the techniques of immunohistochemistry and in situ hybridization, we now show that Id-1 gene expression is specifically detected in the epithelial cells of growing ductal structures during early pregnancy. Using adjacent sections, we determined that Id-1 was expressed in keratin 8/18 positive cells. We also demonstrated that the up-regulation of Id-2 during late pregnancy correlated with the down-regulation of Id-1. Using the yeast-two hybrid system, we identified the bHLH transcription factors, ITF-2A and ITF-2B, as the Id-interacting proteins. The levels of expression of these two splice variants did not change during the transition from growing ductal structures to differentiated alveoli. Therefore Id-1 and Id-2, but not the ubiquitous bHLH proteins, appear to represent the key factors whose expression is modulated during different stages of pregnancy in mouse mammary glands.
Itahana
Yoko
Y
California Pacific Medical Center, Cancer Research Institute, 475 Brannan Street, Suite 220, San Francisco, CA 94107, USA.
Piens
Marie
M
Fong
Sylvia
S
Singh
Jarnail
J
Sumida
Tomoki
T
Desprez
Pierre-Yves
PY
D017398:Alternative Splicing; D000818:Animals; D051778:Basic Helix-Loop-Helix Leucine Zipper Transcription Factors; D005260:Female; D018507:Gene Expression Regulation, Developmental; D018257:Helix-Loop-Helix Motifs; D051798:Inhibitor of Differentiation Protein 1 / Q000235:genetics / Q000378:metabolism*; D051797:Inhibitor of Differentiation Protein 2 / Q000235:genetics / Q000378:metabolism*; D008321:Mammary Glands, Animal / Q000254:growth & development* / Q000378:metabolism; D051379:Mice; D008807:Mice, Inbred BALB C; D009419:Nerve Tissue Proteins / Q000235:genetics / Q000378:metabolism*; D011247:Pregnancy / Q000235:genetics / Q000378:metabolism*; D012333:RNA, Messenger / Q000378:metabolism; D051820:TCF Transcription Factors / Q000235:genetics / Q000378:metabolism*; D000073940:Transcription Factor 4; D020798:Two-Hybrid System Techniques
D051778:Basic Helix-Loop-Helix Leucine Zipper Transcription Factors; C497455:Idb1 protein, mouse; C497452:Idb2 protein, mouse; D051798:Inhibitor of Differentiation Protein 1; D051797:Inhibitor of Differentiation Protein 2; D009419:Nerve Tissue Proteins; D012333:RNA, Messenger; D051820:TCF Transcription Factors; C090743:Tcf4 protein, mouse; D000073940:Transcription Factor 4