title: In vivo evidence for epidermal growth factor receptor (EGFR)-mediated release of prolactin from the pituitary gland.
abstract: Members of the epidermal growth factor receptor (EGFR/ERBB) system are essential local regulators of mammary gland development and function. Emerging evidence suggests that EGFR signaling may also influence mammary gland activity indirectly by promoting the release of prolactin from the pituitary gland in a MAPK and estrogen receptor-α (ERα)-dependent manner. Here, we report that overexpression of the EGFR ligand betacellulin (BTC) causes a lactating-like phenotype in the mammary gland of virgin female mice including the major hallmarks of lactogenesis. BTC transgenic (BTC-tg) females showed reduced levels of prolactin in the pituitary gland and increased levels of the hormone in the circulation. Furthermore, treatment of BTC-tg females with bromocriptine, an inhibitor of prolactin secretion, blocked the development of the lactation-like phenotype, suggesting that it is caused by central release of prolactin rather than by local actions of BTC in the mammary gland. Introduction of the antimorphic Egfr allele Wa5 also blocked the appearance of the mammary gland alterations, revealing that the phenotype is EGFR-dependent. We detected an increase in MAPK activity, but unchanged phosphorylation of ERα in the pituitary gland of BTC-tg females as compared with control mice. These results provide the first functional evidence in vivo for a role of the EGFR system in regulating mammary gland activity by modulating prolactin release from the pituitary gland.
authors.affiliation: Institute of Molecular Animal Breeding and Biotechnology, Gene Center, LMU Munich, Munich 81377, Germany.
authors.forename: Maik
authors.initials: M
authors.lastname: Dahlhoff
authors.forename: Andreas
authors.initials: A
authors.lastname: Blutke
authors.forename: Rüdiger
authors.initials: R
authors.lastname: Wanke
authors.forename: Eckhard
authors.initials: E
authors.lastname: Wolf
authors.forename: Marlon R
authors.initials: MR
authors.lastname: Schneider
mesh_terms: D000818:Animals; D066259:Betacellulin; D001971:Bromocriptine / Q000494:pharmacology; D066246:ErbB Receptors / Q000235:genetics / Q000378:metabolism*; D047628:Estrogen Receptor alpha / Q000235:genetics / Q000378:metabolism; D005260:Female; D006727:Hormone Antagonists / Q000494:pharmacology; D036341:Intercellular Signaling Peptides and Proteins / Q000235:genetics / Q000378:metabolism; D008321:Mammary Glands, Animal; D051379:Mice; D008822:Mice, Transgenic; D018739:Oncogene Proteins v-erbB / Q000235:genetics / Q000378:metabolism; D010902:Pituitary Gland / Q000378:metabolism*; D011388:Prolactin / Q000037:antagonists & inhibitors / Q000235:genetics / Q000378:metabolism*
chemical_list: D066259:Betacellulin; C587852:Btc protein, mouse; D047628:Estrogen Receptor alpha; D006727:Hormone Antagonists; D036341:Intercellular Signaling Peptides and Proteins; D018739:Oncogene Proteins v-erbB; D001971:Bromocriptine; D011388:Prolactin; D066246:ErbB Receptors