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Title: IDENTIFICATION OF ESTROGEN-RESPONSIVE GENES IN THE PARENCHYMA AND FAT PAD OF THE BOVINE MAMMARY GLAND BY MICROARRAY ANALYSIS

Author
item Li, Robert
item MEYER, MATTHEW - CORNELL UNIVERSITY
item Van Tassell, Curtis - Curt
item Sonstegard, Tad
item Connor, Erin
item VAN AMBURGH, MICHAEL - CORNELL UNIVERSITY
item BOISCLAIR, YVES - CORNELL UNIVERSITY
item Capuco, Anthony

Submitted to: Physiological Genomics
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 6/11/2006
Publication Date: 6/20/2006
Citation: Li, R.W., Meyer, M.J., Van Tassell, C.P., Sonstegard, T.S., Connor, E.E., Van Amburgh, M.E., Boisclair, Y.R., Capuco, A.V. 2006. Identification of estrogen responsive genes in the parenchyma and fat pad of the bovine mammary gland by microarray analysis. Physiological Genomics 27(1):42-53.

Interpretive Summary: To catalogue estrogen-responsive genes, prepubertal heifers were used. Eight heifers were intact ± estrogen and eight heifers were ovariectomized ± estrogen. After 3 days of estrogen treatment, gene expression in the parenchyma (containing future mammary secretory cells) and in the fat pad of the bovine mammary gland was analyzed using a high-density microarray containing probes for > 40,000 genes. A total of 125 estrogen-responsive genes were identified. Among these genes are known estrogen-targeted genes. However, the majority of the genes identified were not previously reported to be estrogen-responsive. The distinctive expression patterns regulated by estrogen in parenchyma and fat pad suggest mechanisms of action and reciprocal signaling between cell types.

Technical Abstract: Characterizing estrogen-responsive genes is an essential step towards fully understanding mechanisms of estrogen action during mammary gland development and function. To catalogue these genes, sixteen prepubertal heifers were used in a 2 x 2 factorial with ovarian status (intact or ovariectomized) as the first factor and estrogen (E) treatment as the second (excipient or estradiol). Heifers were ovariectomized at approximately 4.5 months of age and estrogen treatments were initiated one month later. After 3 days of treatment, gene expression in the parenchyma and fat pad of the bovine mammary gland was analyzed using a high-density oligonucleotide microarray. This microarray contained probes representing 40,808 Tentative Consensus sequences from the TIGR Bos taurus Gene Index and 4,575 singletons derived from libraries of pooled mammary gland and gut tissues. Microarray data were analyzed using the SAS Mixed Procedure with permutation testing. A total of 125 estrogen-responsive genes were identified using an experiment-wide permutation-based significance level of p < 0.1. Among these genes are known estrogen-targeted genes such as stanniocalcin 1, alpha-1-antiproteinase, progesterone receptor, nucleobindin 2, insulin-like growth factor 1, and tissue factor pathway inhibitor. However, the majority of the genes identified were not previously reported to be estrogen-responsive. In silico mapping and estrogen response element (ERE) search indicated potential EREs in the promoter regions of some of these novel estrogen-responsive genes. The distinctive expression patterns regulated by estrogen in parenchyma and fat pad suggest mechanisms of action and reciprocal signaling between cell types.