ARS | Publication request: Ontogenic expression of microRNA in bovine mammary gland

Submitted to: Joint Abstracts of the American Dairy Science and Society of Animal Science
Publication Type: Abstract Only
Publication Acceptance Date: March 19, 2007
Publication Date: July 1, 2007
Citation: Capuco, A.V., Coutinho, L.L., Clover, C.M., Minuti, A., Sonstegard, T.S., Boisclair, Y.R., Van Amburgh, M.E., Bertoni, G., Matukumalli, L.K. 2007. Ontogenic expression of microRNA in bovine mammary gland. Joint Abstracts of the American Dairy Science and Society of Animal Science.

Technical Abstract: MicroRNAs (miR) are small RNA molecules (~22 nucleotides) that are important regulators of numerous biological processes, including organ and tissue morphogenesis and function. In this capacity, most miR inhibit protein synthesis by binding to the 3’-untranslated region of targeted mRNA species. Hundreds of genes can be regulated in this fashion. The objective of this experiment was to evaluate expression of miR in mammary tissue from Holstein cows at different developmental and functional stages. Tissues were obtained from: prepubertal heifers (6 mo) that were (1) intact, (2) ovariectomized, (3) intact + estrogen, (4) ovariectomized + estrogen; (5) from primiparous cows, 100-250 d of gestation; (6) from lactating cows, 14 d lactation; (7) from cows during the dry period, 40 d dry and 20 d prepartum. Total RNA was extracted from three or four animals at each stage and pooled to determine patterns of miR expression by hybridization to a microarray containing modified RNA targets complementary to all known mirR. Expression of miR such as miR-221 and miR-127 appeared to be differentially expressed prepubertally. Expression of miR-615 was enhanced by estrogen treatment and miR-29a by ovariectomy. During first gestation, expression of miR-20a was increased. During lactation, miR were typically expressed at low levels, but there was increased expression of a limited number of miR, including miR-326 and miR-350. During the dry period, there was increased expression of miR-542-5p and miR-690. We subjected individual RNA samples to quantitative RT-PCR and confirmed patterns of expression revealed by microarray in 4 of 5 genes tested. Our quantitative RT-PCR results confirmed the utility of evaluating miR expression by microarray and suggested that miR function as regulators of mammary gland development and function.