Submitted to: Journal of Animal Science Supplement
Publication Type: Abstract Only
Publication Acceptance Date: 6/2/2003
Publication Date: 6/21/2003
Citation: Connor, E.E., Capuco, A.V., Sonstegard, T.S., Mota, A.F., Wood, D.L., Garrett, W.M., Bennett, G.L., Williams, J.L. 2003. Quantitative analysis of estrogen-related receptor a, estrogen receptor a and estrogen receptor b throughout bovine mammary gland development [abstract]. Journal of Animal Science Supplement. 81 (Suppl. 1):118.
Technical Abstract: The estrogen-related receptor a (ESRRA) belongs to the steroid hormone receptor family and is thought to function in the regulation of estrogen-responsive genes including lactoferrin and medium-chain acyl coA dehydrogenase. The role of ESRRA in bovine mammary gland development and function is unknown. Expression of ESRRA mRNA was characterized in biopsies of mammary epithelium during multiple stages of bovine mammary gland development in relation to estrogen receptor a (ESR1) and estrogen receptor b (ESR2) using quantitative real-time RT-PCR. Stages of development included prepubertal heifers, pregnant heifers, lactating non-pregnant cows, lactating pregnant cows and non-lactating pregnant cows (n = 2 to 3 animals/stage). In addition, the ESRRA, ESR1 and ESR2 genes were mapped to chromosomes 29, 9 and 10, respectively by linkage and radiation hybrid mapping. Results indicated expression of ESRRA mRNA was greatest in mature cows, regardless of state of pregnancy or lactation and ranged from 20 to 120-fold more than ESR1 and ESR2 transcripts. Expression of ESR2 mRNA was low across all physiological stages and generally less than ESR1 and ESRRA. In pregnant heifers (approx. 100-200 d of pregnancy), levels of all three transcripts were at their lowest or non-detectable. Similar decreases during pregnancy have been reported for mice and may indicate down-regulation by high levels of estradiol during this developmental period. In prepubertal heifers, ESR1 mRNA was at its maximal level of expression but was half as abundant as ESRRA. Our results demonstrate expression of ESRRA, ESR1 and ESR2 mRNAs in bovine mammary gland and suggest a functional role of ESRRA in mammary gland development and lactation.