Expression and Localization of Growth Factors during Mammary Gland Development

Abstract

Growth and differentiation of the mammary gland during development and lactation are controlled by complex hormonal mechanisms. Additionally growth factors are supposed to act as local mediators of the hormonally controlled developmental processes. Mammary tissue for this study was obtained from non pregnant control heifers, primigravid heifers (second part of pregnancy), around parturition, during lactation (early and late) and from dry cows. Using RT-PCR and ribonuclease protections assay (RPA) the expression of the following growth factors was studied in the different phases bovine mammary gland development: Insulin-like growth factor I (IGF-I), insulin-like growth factor II (IGF-II), fibroblast growth factor 1 (FGF-I), fibroblast growth factor 2 (FGF-2), transforming growth factor alpha (TGF-alpha). Additionally the expression of fibroblast growth factor receptor (FGFR) and growth hormone receptor (GHR) was investigated. The cellular distribution pattern of several of these growth factors and GHR was obtained using Immunocytochemical techniques. The detailed expression and localization pattern of these growth factors are presented and their role in the local regulation of the bovine mammary gland is briefly discussed.

Coordinate loss of fibroblast growth factor 2 and laminin 5 expression during neoplastic progression of mammary duct epithelium

“…It is also expressed in mammary epithelial cells at times of expansion and is not expressed at times of involution [9][10][11][12]. Its expression is also lost with malignant transformation and may also play a role in maintaining the differentiated phenotype.…”

Blood Metabolic Profile and Certain Hormones Concentrations in Egyptian Buffalo During Different Physiological States

“…When administered during mid-lactation, however, GH was associated with an increase in mammary cell proliferation in cows (Capuco et al, 2001). Because local production of IGF, as well as expression of IGF receptors are also physiologically regulated (Sinowatz et al, 2000;Plath-Gabler et al, 2001), this explains the differences in the response to GH across physiological states.…”

Regulation of Mammary Development as It Relates to Changes in Milk Production Efficiency

“…When administered during mid-lactation, however, GH was associated with an increase in mammary cell proliferation in cows (Capuco et al, 2001) and an increase in total volume of secretory tissue in goats . Because local production of IGF, as well as expression of IGF receptors are also physiologically regulated (Sinowatz et al, 2000;PlathGabler et al, 2001), this may explain the differences in the response to GH across physiological states.…”

“…In addition, expression of GH receptor has been detected in mammary tissue (Knabel et al, 1998;Sinowatz et al, 2000;Plath-Gabler et al, 2001). The GH receptor belongs to a superfamily of transmembrane receptors, of which PRL receptor is a member (Postel-Vinay & Kelly, 1996).…”