Steroid hormone receptors in target cell membranes.

Numerous reports of rapid steroid hormone effects in diverse cell types cannot be explained by the generally prevailing theory that centers on the activity of hormone receptors located exclusively in the nucleus. Cell membrane forms of steroid hormone receptors coupled to intracellular signaling pathways may also play an important role in hormone action. Membrane-initiated signals appear to be the primary response of the target cell to steroid hormones and may be prerequisite to subsequent genomic activation.

Microtubule and plasmalemmal reorganization: acute response to estrogen.

The acute ultrastructural effects of estrogen in endometrial epithelial cells were investigated by transmission electron microscopy (TEM), with special reference to the microtubule (MT) apparatus and the luminal surface. Ovariectomized rats anesthetized with pentobarbitol sodium were injected intravenously with estradiol-17 beta (E2 beta), 0.5 micrograms/100 g body wt.

Monoclonal antibody toward lysosomal cathepsin B cross-reacts preferentially with distinct histone classes.

1. A set of monoclonal antibodies (Mab) was prepared against cathepsin B (CB) from rat preputial-gland, an organ characterized by rapidly-renewing cell populations, which is a uniquely enriched source of lysosomal enzymes, including CB. Minute amounts of CB are known to be transferred abruptly to the nuclear compartment in a variety of activated cells.

Mechanisms of hormone action: parallels in receptor-mediated signal propagation for steroid and peptide effectors.

The purpose of this contribution is to provide in brief form growing evidence in support of an integrated concept of hormone action that appears to shed fresh light on the information gap between the triggering and the effectuation of outcome of the action of given hormones. In accord with these new concepts there has now arisen a substantial body of data from a wide variety of effectors and target cells that demonstrates an astonishing unity in the actions of hormones of widely dissimilar chemical structure. In a nutshell, it now appears that primary recognition sites for both peptide and steroidal agonists occur at the outer cell surface.

Specific internalization of estrogen and binding to nuclear matrix in isolated uterine cells.

Fractionation of rat uterine cells incubated at 22 degrees C with 0.2 nM [3H]-estradiol-17 beta (E2 beta) was performed to analyze the subcellular distribution of internalized hormone. The postnuclear supernatant of homogenates was resolved in Percoll density gradients into six major fractions defined by enzyme markers.

Chromatin proteins of rat preputial-gland: acute changes in response to estrogen.

The effects of estradiol-17 beta (E2 beta) at 2 or 15 min in vivo on chromatin proteins of rat preputial-gland were analyzed by a battery of electrophoretic methods. Among histones, E2 beta/control ratios for major bands of H1 decreased substantially between 2 and 15 min. In contrast, ratios of H4 increased (P less than 0.

Estrogen action at endometrial membranes: alterations in luminal surface detectable within seconds.

The morphological effects of estrogen on the luminal surfaces of rat endometrial cells were investigated by scanning electron microscopy. Ovariectomized rats were injected intravenously with estradiol-17 beta (E2 beta), 0.5 micrograms/0.

Antibodies against estradiol-binding lysosomal lipoproteins gain access to the nuclear compartment of preputial gland cells under estrogen influence.

The influence of estrogen in provoking nuclear recompartmentation of lysosomal components in hormone-sensitive cells was investigated by immunological analyses of isolated nuclei from the preputial glands of ovariectomized rats. Fixed smears were prepared from ultrapurified nuclei freed of outer membrane, 2-30 min after iv injection of placebo-control solution or submicrogram amounts of estradiol-17 beta. Cytoplasmic contamination was negligible in such preparations, as monitored by vital staining with acridine orange.

Early actions of parathyroid hormone and 1,25-dihydroxycholecalciferol on isolated epithelial cells from rat intestine: I. Limited lysosomal enzyme release and calcium uptake.

Epithelial cells isolated from rat intestine were analyzed for their responsiveness in vitro to parathyroid hormone (PTH) and to 1,25-dihydroxycholecalciferol [1,25-(OH)2D3]. Criteria included determination of whether the agonists promoted extracellular liberation of lysosomal enzyme activities above control values during incubation in Ringer's solution at 22 C. PTH-augmented release of the representative hydrolase activities, cathepsin B and acid phosphatase, to the particle-free supernatant fraction of the medium was evident within 5 min of hormone treatment and was sustained in statistically significant degree for at least 30 min to greater than 20% above control levels.

Lysosomal cathepsin B-like activity: mobilization in prereplicative and neoplastic epithelial cells.

Extracellular release of acid thiol proteinase activity by prereplicative and neoplastic epithelial cells was studied in serum-free, chemically defined media (CDM) in vitro. Cells isolated from urinary bladder of male bullfrogs and endometrium of ovariectomized rats each showed preferential secretion of cathepsin B-like (CB) activity within 30 min after exposure to carcinogenic nitrosamines (5 X 10(-4) M) or to mitogenic estrogen 1 X 10(-9) M), respectively. In contrast, release of such proteinase, and stimulation of cell proliferation were far less extensive in rat preputial gland cells treated with estradiol-17 beta.

Partial purification and characterization of oestrogen receptors in subfractions of hepatocyte plasma membranes.

To assess the subcellular distribution of oestrogen-binding components in their native state, plasma membrane and other cell fractions were prepared from hepatocytes in the absence of [(3)H]oestradiol-17beta. Cells from livers of ovariectomized rats were disrupted, with submaximal homogenization in buffered isotonic sucrose with CaCl(2) and proteinase inhibitor, and fractionated by using isotonic media. Fractions were characterized by determinations of enzyme activities, biochemical constituents and ligand binding.

Luteinizing hormone-accelerated redistribution of lysosome-like organelles preceding dissolution of the nuclear envelope in rat oocytes maturing in vitro.

Maturation of the mammalian oocyte is characterized in part by dissolution of the nuclear envelope, or germinal vesicle breakdown (GVB). By fluorescence microscopy after vital uptake of acridine orange (AO), redistribution and perinuclear accumulation of organelles corresponding to lysosomes occur before GVB in rat oocytes undergoing meiotic maturation in vitro. In follicle-enclosed oocytes explanted during the preovulatory gonadotropin surge (GS) and individually cultured as such in chemically defined medium at approximately 22 degrees C, lysosomes aggregated into disperse clusters after 30 min; by 60 min, perinuclear concentration of lysosomes and their essential disappearance from the cortical ooplasm were observed.

Estrogen-induced membrane alterations and growth associated with proteinase activity in endometrial cells.

Endometrial cells isolated from uteri of ovariectomized rats were treated in vitro with 1 X 10(-9) M estradiol-17 beta (E2beta) to analyze early changes in membrane properties during hormone-induced growth. After 30-min exposure to E2beta at 22 degrees C, cells exhibited an enhanced capacity to bind erythrocytes (hemadsorption) in the presence of concanavalin A (Con A) to 237% of the level in paired controls. Fluorescence microscopy revealted that approximately 25% of cells exposed to E2beta, but not estradiol-17 alpha (E2alpha), showed a redistribution into polar clusters of Con A-binding sites that were dispersed in random patches at the external surfaces of control cells.

Elevated serum cathepsin B1 and vaginal pathology after prenatal DES exposure.

Activities of the lysosomal enzymes, cathepsin B1 (CBI), beta-glucuronidase, and beta-N-acetyl-D-glucosaminidase, as well as sialyl transferase, alkaline phosphatase, and placenta-like alkaline phosphatase, were determined on blind-coded serums from 99 women exposed to diethylstilbestrol (DES) in utero and 40 unexposed subjects of comparable age range. Cathepsin B1 averaged 100%, 1040% (P less than 0.001), 2720 % (P less than 0.

Cinemicrographic analysis of cytoplasmic and nuclear events associated with germinal vesicle breakdown in rat oocytes exposed to LH in vitro.

Cinemicrography, with Nomarski differential interference optics, was used to study the motion of cytoplasmic organelles and events leading to germinal vesicle breakdown (GVB) in rat oocytes perfused with a defined medium with or without LH. Initially, cytoplasmic organelles, 0-3--1-5 micrometer diam., appeared to move randomly and were uniformly distributed.