Regulation of alpha 2(I), alpha 1(III), and alpha 2(V) collagen mRNAs by estradiol in the immature rat uterus.

We show that mRNAs for alpha 2(I), alpha 1(III), and alpha 2(V) collagens are regulated by estradiol in the immature rat uterus. Clones for alpha 2(I) and alpha 1(III) collagen were induced in a cDNA library prepared from estradiol-stimulated rat uterine mRNA. Alpha 2(I) collagen cDNA was identified by its characteristic hybridization pattern on Northern blots and hybridization to known probes. The sequence of alpha 1(III) collagen cDNA showed 91% amino acid sequence homology with the corresponding 525-nucleotide segment of human alpha 1(III) procollagen cDNA. Type I and type III collagen mRNAs were coordinately regulated, and showed peaks of induction at 4 and 24 hr. Three injections of estradiol, 24 hr apart, produced induction maxima 24 hr apart. The third induction, however, was suppressed relative to the first, suggesting that estrogen-stimulated factors may act to negatively regulate the uterine response to estrogen.