Regulation of Alpha 2 (I),Alpha 1 (III),and Alpha 2 (V) Collagen mRNAs by Estradiol in the Immature Rat Uterus

Abstract

We show that mRNAs for alpha₂(I), alpha₁(III), and alpha₂(V) collagens are regulated by estradiol in the immature rat uterus. Clones for alpha₂(I) and alpha₁(III) collagen were induced in a cDNA library prepared from estradiol-stimulated rat uterine mRNA. Alpha₂(I) collagen cDNA was identified by its characteristic hybridization pattern on Northern blots and hybridization to known probes. The sequence of alpha₁(III) collagen cDNA showed 91% amino acid sequence homology with the corresponding 525-nucleotide segment of human alpha₁(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.