Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: EC:3.2.1.36 (hyaluronidase)
 4,606 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The properties of gonadotropin-releasing hormone (GnRH) receptors were analyzed in isolated pituitary cells prepared by enzymatic dispersion with trypsin or collagenase-hyaluronidase. The initial impairment of LH responses to GnRH in isolated cells prepared by both methods was reversed during culture for 2 days in multiwell vessels. However, specific binding sites for GnRH, assayed by equilibration with [125I]iodi0[D-Ser(t-BU)6]des-Gly10-GnRH N-ethylamide (GnRH-A) were demonstrable in collagenase-dispersed cells, both initially and after 2 days in culture. Cellular uptake of GnRH-A was temperature dependent, with rapid and saturable binding to a limited number of specific receptor sites with high affinity for the labeled analog (Ka = 4.0 +/- 0.8 X 10(9) M-1). These sites showed common binding specificity for GnRH-A and the native GnRH peptide, with significantly lower affinity for the natural peptide (Ka = 2.3 X 10(7) M-1). Other protein and peptide hormones, including ovine LH, ovine PRL, hCG, TRH, somatostatin, and angiotensin II (up to 10(-6) M) did not inhibit binding of GnRH-A to its receptors. Cellular binding of GnRH-A was followed by increased cGMP production and LH release within 10 min. The analog was 50 times more potent than native GnRH in stimulating LH release. The Kact values derived for GnRH and GnRH-A were 0.5 and 0.01 nM, respectively, considerably lower than the Kd values of 50 and 0.25 nM derived from receptor binding analysis. These results indicate that GnRH receptors can be identified in isolated pituitary cells, in which peptide binding is followed by increased cGMP production and LH release. The impaired LH responses in acutely dispersed pituitary cells are not due to the loss of receptor sites but to a reversible postreceptor defect. Occupancy of about 20% of the GnRH-binding sites elicits a near-maximal LH response, indicating the nonlinearity of GnRH-receptor coupling to secretory responses in the cultured gonadotroph.
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PMID:Characterization of gonadotropin-releasing hormone receptors in cultured rat pituitary cells. 625 Jul 93

Monocellular suspensions of epithelial cells from mammary glands of rabbits at 20-22 days of pregnancy were prepared by sequential dissociation with collagenase-hyaluronidase followed by Pronase. Maintenance in D-valine-substituted minimum essential medium (D-valine-MEM) supplemented with 10% dialyzed calf serum yielded monolayers enriched for rabbit mammary epithelial cells (RMEC). RMEC specifically and reversibly bound bovine PRL with Ka = 1.41-1.85 x 10(9)M-1. Association of lactogen with RMEC receptor followed bimolecular reaction kinetics with rate of 5.17 (+/- 0.75) x 10(5)M-1 sec-1 at 24 C, and 1.03 (+/- 0.11) x 10(6)M-1 sec-1 at 37 C. Dissociation was first order (K-1 = 5.97 (+/- 0.70) x 10(-5) sec-1) and was unaffected by the presence of lactogen. Specific binding determined with an excess of unlabelled bPRL was 66-77% of the total binding, and was optimal at pH 7.4. The binding reaction reached equilibrium in 2 h at 37 C, in 3 h at 24 C, and after 24 h at 4 C. Studies of binding capacity revealed the presence of 4.6-6.3 x 10(3) sites per cell, competition for which was limited to hormones demonstrating lactogenic activity. Recovered lactogen was not degraded by incubation with or dissociation from RMEC. Approximately 25% of the radioactivity remained associated with the cells even upon prolonged incubation. These studies demonstrated several advantages of RMEC for the investigation of hormone-receptor interaction and receptor regulation.
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PMID:Kinetic characterization of [125I] iodo-prolactin in binding to primary monolayer cultures of rabbit mammary epithelium. 628 30

An enriched fraction of human decidual cells that synthesizes and releases human PRL (hPRL) was obtained by isopycnic centrifugation of collagenase- and hyaluronidase-dispersed cells through Percoll. The cells that synthesized and released hPRL banded at a density of 1.017-1.045 g/ml, an area of the gradient comprising only a small percentage of the total decidual DNA. The enriched cells formed distinct colonies in culture and contained hPRL, as evidenced by indirect immunofluorescent staining with anti-PRL serum. Plated at a density of 5.0 x 10(5) cells/well, the cells produced hPRL at a mean rate of 8.1 +/- 1.1 ng/microgram DNA . 24 h (mean +/- SD) for 8 days. Like decidual explants, the enriched cells responded to phospholipase A2 (0.1 U/ml) with a 54% decrease in hPRL release and to placental conditioned medium (0.5 mg protein/ml medium) with a 62% increase. Insulin (8.3 x 10(-7) M), progesterone (10(-5) - 10(-12) M), and estradiol (10(-5) - 10(-12) M) did not affect hPRL release over 6 days. These results indicate that enriched PRL-releasing cells, obtained by the isopycnic centrifugation of collagenase- and hyaluronidase-dispersed cells, are a useful model for the study of the synthesis and release of PRL.
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PMID:Characterization of the synthesis and release of prolactin by an enriched fraction of human decidual cells. 630 Jan 79

Human decidua contains resident decidual cells alongside a population of bone marrow-derived cells, among which macrophages and large granular lymphocytes are most abundant. We hypothesized that soluble effectors produced by bone marrow-derived cells may modulate the function of the decidual cells. To investigate this, a cell purification protocol was devised that involved digestion of first-trimester decidua with collagenase and hyaluronidase to produce a mixed stromal cell suspension from which the bone marrow-derived cells were removed using immunomagnetic beads coated with anti-CD45. The resulting stromal cells were maintained in culture in the presence of progesterone and were found to produce PRL. The effect of a panel of cytokines on PRL production was examined. Tumor necrosis factors-alpha and -beta had a dose-dependent inhibitory effect, and tumor necrosis factor receptors were identified on the cells. Interleukin 1 alpha and 1 beta, platelet-derived growth factor, and transforming growth factor-beta 1 were also found to inhibit PRL production, and platelet-derived growth factor and transforming growth factor-beta 1 stimulated cell proliferation. These findings suggest an interaction between the immune and endocrine systems in regulating the maternal environment of early pregnancy.
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PMID:Comment: effect of cytokines on prolactin production by human decidual stromal cells in culture: studies using cells freed of bone marrow-derived contaminants. 798 96