High molecular mass forms of epidermal growth factor in pig uterine secretions

Abstract

Accumulating evidence suggests that uterine luminal fluids contain a variety of polypeptide growth factors and cytokines that, it is speculated, have roles in the development, growth and differentiation of the uterus and, during pregnancy, in the growth and survival of the embryo. Although epidermal growth factor (EGF) has previously been identified by radioimmunoassay and immunohistochemistry in the pig uterus, there have been no detailed studies of the secreted EGF protein. EGF was therefore purified from uterine flushings and uterine fluids of nonpregnant pigs of mixed breed using a variety of ion-exchange chromatography steps. Uterine flushings and fluids contained an anionic factor(s) that at 4 degrees C competed with 125I-labelled mouse EGF for binding to EGF receptors on an endometrial carcinoma cell line and stimulated DNA synthesis in Balb/c mouse 3T3 fibroblasts. As analysed by gel filtration, uterine fluids contained a 3-6 kDa factor that stimulated 3T3 cell DNA synthesis and was a competitor of cellular 125I-labelled EGF binding. Gel filtration further revealed that uterine flushings and fluids contained, respectively, 45 kDa and 40-70 kDa moieties that were mitogenic and that bound to the EGF receptor. SDS-PAGE and western blotting using an antiserum specific for pig EGF revealed immunoreactive forms of EGF of approximately 25 kDa in partially purified uterine flushings. It is concluded that uterine secretory EGF occurs, at least in part, as high molecular mass proteins. The ability of these high molecular mass EGFs to bind to and activate the EGF receptor suggests that they may be authentic ligands for the EGF receptor in utero.

Only a Truncated Epidermal Growth Factor Receptor Protein is Present in Porcine Endometrium

“…Because of the lack of a functional receptor form, an effect of growth factors of the EGF-family on porcine endometrial epithelium via the EGF-R can be excluded. EGF [9] and HB-EGF [10] have been demonstrated previously in porcine endometrium and flushings, with additional high molecular weight forms of EGF being present in the uterine fluids [18]. A function of these growth factors would depend on the expression of other receptors of the EGF-R family in the pig uterus.…”

Chicken Pleiotrophin: Regulation of Tissue Specific Expression by Estrogen in the Oviduct and Distinct Expression Pattern in the Ovarian Carcinomas

“…Recently, Muramatsu and collegues [56] reported that mice deficient in both Ptn and Mk were infertile and had abnormal estrous cycles with long periods of proestrus and diestrus and short periods of estrus [48]. In addition, the presence of PTN in the porcine uterus and uterine flushings during early pregnancy may be a member of the regulators of implantation and conceptus development [49], [50]. In the present study, PTN mRNA and protein were most abundant in the LE of the isthmus and shell gland, but detectable at lower abundance in GE in each segment.…”

Expression of Growth Factor Ligand and Their Receptor mRNAs in Bovine Ova during In Vitro Maturation and after Fertilization In Vitro.

“…First, several growth factors have been shown to be present in follicular fluid [9,23] and female reproductive tract [5,7]. Second, the addition of exogenous growth factor to the culture medium results in beneficial effect on oocyte maturation and/or embryo development in bovine ova [12,14,15,26,31].…”