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C M Szego

Publications and source records attributed to C M Szego.

18 recordsLinked to original sources
PubMed1979

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. These hormore-induced membrane alterations were abolished by prior treatment of cells with inhibitors of thiol proteinase activity of the cathepsin B1 (CB1) type, such as leupeptin and iodoacetate. Leupeptin at 4.5 X 10(-7) M also reduced the affinity of [3H]E2beta binding to intact cells but did not influence specific binding of the hormone to macromolecular components of cytosol. A pronounced increase in the availability of endogenous CB1, But not of alkaline phosphatase, succinate, or lactate dehydrogenase, in the extracellular media was elicited within 30 min after E2beta treatment. In cells cultured in chemically defined medium for up to 48 h, E2beta, but not E2alpha, enhanced cell proliferation and stimulated [3H]thymidine incorporation into macromolecular form. These E2beta-induced effects were abolished by prior treatment of cells with liposome-entrapped leupeptin at a final concentration of 7 X 10(-8) M. The net rate of intercellular adhesion among endometrial cells was also enhanced by E2beta. This hormonal response was diminished by prior exposure to leupeptin. Fractionation of cells by selection for adhesiveness due to E2beta exposure for 30 min yielded a subpopulation of rapidly dividing cells which surpassed their less adhesive counterparts in cathepsin secretion and in Con A-mediated hemadsorption. These results indicate that leupeptin-sensitive proteinase activity may contribute to membrane and growth modifications elicited by E2beta treatment in endometrial cells.

Animals↗
PubMed1979

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. GVB occurred within 120 min. In contrast, follicle-enclosed oocytes explanted before the GS displayed a generally homogeneous distribution of lysosomes and intact GV for up to 5 h in culture. In oocytes aspirated from follicles before the GS, partially denuded of granulosa cells, and cultivated without added hormone, most lysosomes concentrated around the GV within 60 min, with GVB occurring generally by 120 min. Luteinizing hormone (LH) added in vitro to the isolated preparation at 3 or 30 x 10(-8) M sharply accelerated these events. The effects of LH, not seen with 1.5 x 10(-8) M hormone, were blocked by anti-LH IgG. Up to 60 x 10(-8) M follicle-stimulating hormone or 80 x 10(-8) M prolactin were ineffective in accelerating lysosome redistribution or GVB. After GVB, lysosomes became once again uniformly dispersed and unresponsive, even to 60 x 10(-8) M added LH, a finding consistent with tachyphylaxis of target cells by independent criteria. The present data, all statistically significant at P less than 0.05, demonstrate that mobilization of lysosomes before GVB is a specific response to factors that promote resumption of meiotic maturation of rat oocytes.

Animals↗
PubMed1978

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 0.001), and 4760% (P less than 0.001) of controls in DES-exposed women with no genital tract abnormalities (N = 11), adenosis (N = 68), adenosis with concomitant dysplasia (N = 15), and clear-cell adenocarcinoma (N = 5), respectively. The later two groups also exhibited 0.01). Activities of the other four enzymes in serums of DES-exposed women were unchanged from those controls, suggesting that alterations in CBI were not due to generalized increases in lysosomal membrane instability or other gross cellular damage. In 2 DES-exposed women with clear-cell adenocardinoma, from whom serial samples were available, preoperative levels of serum CBl fell from a mean of 4280% to values indistinguishable from controls by 7--12 days after tumor excision, concurrently with objective signs of remission. Recrudescence of serum CBI levels preceded by at least 3 months clinical evidence of persistent adenosis accompanied by vaginal dysplasia. Although the nature of the increments in CBI-like activity in the majority of subjects with DES-related pathology remains to be determined, the findings may complement present methods of physical diagnosis and prognosis.

Acetylglucosaminidase↗
PubMed1977

Estradiol-induced redistribution of lysosomal proteins in rat preputial gland. Evidence from immunologic probes.

The influence of estrogen on the subcellular localization and distribution of lysosomal components of preputial gland was investigated in the ovariectomized rat. Antisera of high titer and specificity toward high-density lysosomal lipoproteins of this organ were raised in rabbits. The immunologic effectiveness of the IgG fraction so obtained was confirmed by microcomplement fixation, immunodiffusion, and immunoelectrophoresis. By both direct and indirect immunofluorescence techniques, cryostat sections of preputial gland from the control animals exhibited pinpoint cytoplasmic fluorescence, of dimensions corresponding to those of lysosomes. In contrast, specific immunoreactive material in corresponding target cells from animals receiving 0.1 microng of estradiol-17 beta/100 g body wt only 2 min earlier was distributed more homogeneously, indicating release of antigen from the membrane-bounded organelles. Moreover, specific immunofluorescence became evident at cell surfaces and in peri- and supranuclear localization, sites essentially negative in the controls. These effects were intensified at 15 min, as well as by maximal physiologic dose (0.5 microng/100 g body wt) of hormone. The relatively less active epimer, estradiol-17 alpha, exhibited only very limited effectiveness by some of these criteria. These observations, taken together with independent biochemical and ultrastructural evidence, lead to the conclusion that structural labilization of lysosomal constituents and their translocation to the nuclear compartment are early correlates of estrogen action.

Animals↗
PubMed1977

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. A gradually increasing vigour of organellar movement, saltatory translocation of organelles and discontinuous convergent flow of groups of organelles around the nucleus were observed. Ultimately, most of the organelles, which possessed several properties indicative of lysosomes, accumulated around the nucleus. In the presence of 5--6 micrograms LH/ml perfusate, GVB was usually complete by 80 min, whereas in the absence of hormone, or in the presence of LH + antiserum to LH, GVB took up to 130 min. A sudden slight decrease in nuclear size, undulating activity in the nuclear envelope, and the appearance of intranuclear filaments indicated imminent GVB. The appearance of spherical bodies at the nucleolar surface, and the subsequent mobilization and collapse of the nucleolus in the nucleoplasm, were advanced events in the nuclear response. It is suggested that LH promotes GVB trought activation of lysosomes.

Animals↗
PubMed1976

Differential effects of vasopressin on the water, calcium and lysosomal enzyme contents of mitochondria-rich and lysosome-rich (granular) epithelial cells isolated from bullfrog urinary bladder.

Treatment of bullfrog urinary bladder with arginine vasopressin (AVP) elicited a dose-dependent increase in the basal movement of water and sodium across isolated tissues. Epithelial cells from the mucosal surface and incubated with 10 mU AVP/ml for 30 min retained a greater amount of intracellular water and calcium than cells not treated with hormone. The epithelial cells were further separated into two major fractions by density gradient centrifugation; cells damaged during these manipulations were separated from viable cells and discarded. Morphologcal examination of the two respective fractions indicated that they largely consisted of mitochondria-rich (MR) and granular (G) cell types which line the lumen of bullfrog bladder. The calcium content of MR cells averaged 25% greater than that of G-type cells. G cells had a markedly higher content of the characteristic lysosomal hydrolases, acid phsophatase and cathepsin B1, than that found in MR cells. Incubation of G cells with AVP elicited significant increments in water and calcium contents and extracellular release of lysosomal enzymes as compared to untreated cells. Among MR cells treated with AVP, cell calcium declines slightly but no significant increase in water content or extracellular hydrolase activity was detected in comparison with paired control cells. The physiological significance of acid proteinase release from G cells treated with AVP was evaluated in experiments with intact bladder. Proteinase inhibitors which suppress the activity of cathepsin B1 selectively antagonized the action of hormone on water permeation. The data suggest that alterations in the calcium and lysosomal hydrolase activity associated with G cells exposed to AVP may contribute to the hormone-induced water flow observed across the intact epithelium.

Acid Phosphatase↗
PubMed1976

Early membrane alterations in isolated cells treated in vitro with chemical carcinogens.

Membrane alterations were detected in isolated epithelial cells treated in vitro with 5 x 10(-4) M dibutylnitrosamine (DBN) or 1.2 x 10(-9) M diethylstilbestrol (DES) for 30 min. Addition of DBN to bladder cells and DES to endometrial cells elicited a striking increment in Con A-mediated hemadsorption, but not Con A binding, to the treated cells as compared to those not treated with carcinogens. Concomitantly, release of the lysosomal proteinase, cathepsin B1, to the extracellular medium was essentially doubled in the preparations exposed to the carcinogens, as compared to corresponding controls. The increased cellular hemagglutination in response to carcinogen treatment was significantly reduced by prior incubation of the epithelial cells with ovomucoid, a proteinase inhibitor that suppresses the activity of cathepsin B1.

Animals↗
PubMed1976

Steroid-protein binding: from circulating blood to target cell nucleus.

The concept of protein binding of steroid hormones is traced from its origins through the period of confirmation and initial extension. Further considerations include cell surface recognition sites, subcellular sources of binding protein, and the new evidence that lysosomes participate in the translocation and intranuclear penetration of the hormone in steroid target cells. This short review thus aims to provide a link between current investigations and the ideas upon which they have been based.

Animals↗
PubMed1975

Surface modifications evoked by antidiuretic hormone in isolated epithelial cells: evidence from lectin probes.

Epithelial cells (80-90% "granular" type) were isolated from urinary bladders of Bufo marinus and Rana catesbiana. The inhibitory effect of alpha-methyl-D-mannoside on fluorescein-labeled concanavalin A (Con A) binding to these cells indicates that they possess specific binding sites for Con A. The lectin also mediates adsorption of erythrocytes to these cells. Both Con A binding and Con A-mediated hemadsorption to epithelial cells are depressed at 4 degrees C, as compared with cells maintained at 22 degrees C. Elevation of temperature to 37 degrees C, however, enhances hemadsorption independently of alterations in lectin binding. Treatment of cells with antidiuretic hormone (ADH) at 22 degrees C followed by 15 min of incubation at 22 degrees or 37 degrees C before exposure of cells to Con A promotes increments in Con A-mediated hemadsorption, but not in lectin binding, at 22 degrees or 37 degrees C. These hormonal effects are not significant when hemadsorption is assayed at 4 degrees C. Treatment of cells with another octapeptide, angiotensin, elicits a small, but significant, increment in hemadsorption to epithelial cells which is likewise uninfluenced by quantitative changes in lectin binding. Collectively, these data and other independent observations suggest that treatment with octapeptide hormones acts to enhance the redistribution and aggregation of lectin-binding proteins in the membranes of granular epithelial cells from amphibian urinary bladder. Such changes, in turn, may contribute to the alterations in membrane transport properties which characterize the hormonal response.

Angiotensin II↗
PubMed1975

Steroid hormone-responsive, isolated endometrial cells.

Addition of estradiol-17beta in vitro to suspensions of isolated endometrial cells resulted in significant effects on glucose, water and electrolyte metabolism. Cells were prepared from uterine tissues of ovariectomized rats. In part, the procedures involved incubation with collagenase in Ca2+-, Mg2+-free, phosphate-buffered mammalian Ringer's solution, followed by restoration of divalent cations before gentle scraping of the endometrium from the underlying smoothmuscle. Cells were then disaggregated, washed, separated from coarse and fine debris, and incubated in an enriched medium for 2 h before the start of all experiments. Cellular integrity was established by measurement of electrolyte contents and by dye exclusion methods. Substantial production of 14CO2 from glucose-U-14C by the cell suspensions provided further evidence of cell viability. Estradiol-17beta, 10-9M, elicited significant increments in sodium and water contents within 2 h. Addition of estradiol-17beta, but not the alpha-epimer, also resulted in a significant increase in the yield of 14CO2 as early as 1.5 h, peaking at 2 h. The responses were dose-dependent between 10-10M through 10-8M. The stimulatory effect of estradiol-17beta at 10-9M was abolished in the presence of 3 times 10-6M cortisol or by cellular homogenization. Epithelial cells isolated from rat urinary bladder responded significantly to 6 times 10-9M aldosterone but not to estradiol-17beta, demonstrating specificity of the target site. These data lend further support to the suggestion that a primary action of estrogen in its target cell involves specific changes in the ionic and biochemical profile of the cytoplasm which may ultimately be communicated to the nucleus.

Aldosterone↗
PubMed1975

Surface modifications evoked by estradiol and diethylstilbestrol in isolated endometrial cells: evidence from lectin probes and extracellular release of lysosomal protease.

Endometrial cells were isolated from the uteri of ovariectomized rats. The inhibitory effect of alpha-methyl-D-mannoside on fluorescein-labeled concanavalin A (Con A) binding to these cells indicates that they possess specific binding sites for Con A. The lectin also mediates adsorption of homologous erythrocytes to these cells. Both Con A binding and Con A-mediated hemadsorption to endometrial cells are depressed at 4 C compared with these functions in cells maintained at 22 C. Gross elevations in lectin-mediated hemadsorption to endometrial cells are evident following prior exposure to 1 X 10(-9)M concentrations of diethylstilbestrol (DES) or estradiol-17beta, but not to the physiologically inactive 17 alpha-epimer, at 22 C. The enhancement of hemagglutinability cannot be attributed to a corresponding increase in lectin binding at 22 C. Although estrogen treatment elicited significant increments in Con A binding as early as 5 min after addition of estrogen to cell suspensions, the increment in agglutination attributable to hormone treatment consistently ranged from 1.5-3 times greater than the increase in lectin binding. These estrogenic effects were reduced by incubation of the endometrial cells at 4 C or when cortisol, 3 X 10(-6)M, was present with estradiol-17beta. In parallel experiments, treatment with DES and estradiol-17beta, but not estradiol-17 alpha, also enhanced the release of cathepsin B 1 and acid phosphatase from uterine segments into the particle-free extracellular media in which the tissues had been incubated for 30-60 min. The marked increment in the extracellular activity of the lysosomal hydrolases induced by estrogen treatment was suppressed in cells incubated at 4 C or when cortisol was present concomitantly. These and related data suggest the hypothesis that acute increments in lysosomal hydrolase activity may contribute to cell surface alterations which have been described in both normal and aberrant processes of cell growth.

Acid Phosphatase↗