Electrophoretic Analyses of Secreted Human Endometrial Proteins: Identification and Characterization of Luteal Phase Prolactin*

Abstract

Endometrial protein synthesis and secretion throughout the menstrual cycle was studied by slab gel electrophoretic analysis of [35S]methionine incorporation into protein during short term culture of human endometrial tissue. A minimum of five protein bands that fluctuate during the menstrual cycle were identified on one-dimensional gels. Those with mol wt of 28K, 35K, 51K, and 59K decreased in the luteal phase, whereas a broad 25K band was induced in the luteal phase. This broad band was identified as two species of glycosylated PRL by antihuman PRL immunostaining and [3H]glucosamine incorporation.

Synthesis and Secretion of Proteins by the Endometrium and Decidua

“…This protein was not observed by Strinden and Shapiro (1983), whose studies ended, however, on day 18 after the last menstrual period (LMP), before substantial EP15 synthesis has begun. The major secretory protein of the endometrium during the mid to late luteal phase, reported by Heffner et al (1986), showed similar electrophoretic properties to EP15 in one and two dimensional polyacrylamide gel systems, but these authors suggested that the protein represented glycosylated prolactin (G-PRL). It is likely, however, that the properties of EP15 and G-PRL are similar in the gel system used and that G-PRL is actually a minor product.…”

“…This form of prolactin (Lewis et al 1985) has also been detected in amniotic fluid, and during early pregnancy a greater proportion of prolactin exists in this form (cited in Lee and Markoff 1986). Related to this observation may be the report that during the menstrual cycle only the glycosylated form was detected by western blotting in endometrial incubation medium (Heffner et al 1986). The full implications of these reports have yet to be assessed, since the function of G-PRL compared to prolactin is unknown.…”

“…This approach has been used to study the profile of endometrial synthesis and secretion in the menstrual cycle (Strinden and Shapiro 1983;Bell et al 1986a;Heffner et al 1986) and during pregnancy (Bell et al 1985a). In two of these studies the effect of short-term exposure to progesterone in vitro was also examined (Strinden and Shapiro 1983;Bell et al 1986a).…”

Synthesis and Release of Glycosylated Prolactin in Transfected Cells with Human Prolactin Complementary Deoxyribonucleic Acid.

“…It is also detected in endometrial and decidual tissues [15,16]. In addition, Pellegrini et al [17] have reported that human prolactinoma cells secrete both G-PRL and nonglycosylated (NG)-PRL in vitro.…”

Partial primary sequence of a human endometrial epithelial progesterone dependent protein secreted in vitro

“…Our group (2)(3)(4)(5)(6)(7)(8) and several others (9)(10)(11)(12)(13)(14)(15)(16)(17) have examined luteal phase human uterine fluids and/or media from human luteal phase endome¬ trial tissue incubations for proteins that are both dependent on progesterone for their secretion and specific to the endometrium. Several such proteins have been identified, among them a progesteroneregulated form of endometrial prolactin (10), the 50 kD protein of Strinden & Shapiro (12), pro¬ gesterone endometrial protein (PEP) (11), a2-globulin (a2-PEG) (13), placental protein (14) (PP14) (16), the 51 and the 29 kD proteins described by Maudelonde & Rochefort (17), and protein #27 (5)(6)(7)(8) (Dichek et al, submitted).…”