Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: EC:3.2.1.31 (beta-glucuronidase)
 7,680 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The purpose of this study was to adduce further evidence for a paracrine role for human decidual relaxin (Rlx) in the remodelling of collagen in the fetal membranes in the peripartal period. The binding of [125I]porcine Rlx to membrane-enriched fractions from fetal membranes as well as from dispersed cells from the fetal membranes was used to demonstrate the presence of specific Rlx receptors. Rlx added in vitro to cultured amnion/chorion cells increased the release of plasminogen activator and collagenase into the medium. Rlx had no effect on the release of beta-glucuronidase. An in vivo correlate of these in vitro results was obtained, the detection of plasminogen activator and collagenase in amniotic fluids. The active fraction of collagenase was increased in amniotic fluids collected after spontaneous rupture of the membranes. PRL, hCG, estrogen, and progesterone added in equimolar amounts to cultured amnion/chorion cells from elective cesarean sections and normal term deliveries also effected the release of plasminogen activator and collagenase. The greatest effects were found in cells from cesarean section tissue, in terms of the stimulation of plasminogen activator release by Rlx and PRL and of collagenase release by prostaglandin F2 alpha and, to a lesser extent, by Rlx, PRL, and hCG. We conclude that human fetal membranes are targets for a number of hormones, including the decidual paracrine hormones Rlx, PRL, and prostaglandin F2 alpha as well as estrogen, progesterone, and hCG. These hormones act to release or inhibit the enzymes involved in collagen breakdown before rupture of the fetal membranes.
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PMID:The human fetal membranes: a target tissue for relaxin. 300 43

Effects of the dopamine agonist 2-bromo-alpha-ergocryptine (bromocriptine) on plasma and pituitary PRL and enzyme activities in lactating and postlactating rats have been investigated. Lactating rats which had been suckling their young for 3 days were given a single sc injection of bromocriptine or solvent. The treated and control animals were divided into 2 further groups. One group (lactating rats) was permitted to suckle their pups for a further 12 or 24 h; the young were removed from the other group (postlactating rats). Homogenates were prepared from the anterior pituitaries and assayed for organelle marker enzyme activities. When 0.5-500 micrograms bromocriptine were administered to lactating rats for 24 h, pituitary PRL was increased by all doses, but only the 500-micrograms dose significantly reduced plasma PRL. Total protein was unchanged, lysosomal acid PRL proteolytic activity increased 8-fold, N-acetyl-beta-glucosaminidase and beta-glucuronidase (lysosomes) were unchanged, acid phosphatase (lysosomes and endoplasmic reticulum) was increased by three of four doses, 5'-nucleotidase and alkaline phosphatase (plasma membrane) were increased 4-fold, neutral-alpha-glucosidase (endoplasmic reticulum) and malate dehydrogenase (mitochondria) were unchanged, and catalase (peroxisomes) was significantly increased. Bromocriptine (500 micrograms) administration to lactating and postlactating rats for 12 and 24 h significantly decreased the pituitary DNA but not the total protein content of the pituitaries in all animals. The lysosomal acid PRL proteolytic activity and the lysosomal enzyme activities, N-acetyl-beta-glucosaminidase and beta-glucuronidase, were increased by suckling withdrawal alone. Acid PRL proteolytic activity was further increased (to 18-fold) by coadministration of bromocriptine, whereas the increase in the activities of the other lysosomal marker enzymes was blocked. Malate dehydrogenase activity (mitochondria) was also increased by litter removal and blocked by bromocriptine. The activity of the plasma membrane markers 5'-nucleotidase and alkaline phosphatase were increased by litter removal, and bromocriptine further increased both enzyme activities. The activity of neutral-alpha-glucosidase (endoplasmic reticulum) was unchanged by any treatment. The results demonstrate that bromocriptine produces significant changes in the activities of lysosomal marker enzymes, particularly acid PRL proteolytic activity, as well as marker enzymes of plasma membranes and other organelles in pituitaries of lactating and postlactating rats.
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PMID:Effects of bromocriptine on pituitary organelle marker enzyme activities in lactating and postlactating rats: selective activation of lysosomal prolactin proteolytic activity. 608 93

Chloroquine is widely used as a lysosomal enzyme inhibitor, and while effects on DNA repair and membrane recycling have also been reported, there has been no investigation of effects on the processing of secretory products. To determine whether chloroquine had any effect on secretion and secretory organelles, we monitored the effects of low concentrations (10(-6) M) of chloroquine on a cell population which normally secretes copious amounts of a simple polypeptide (PRL) in vitro and in which there exists a subpopulation of cells which releases PRL very rapidly after synthesis. Cultured anterior pituitary cells were exposed to 10(-6) M chloroquine for 6, 12, 24, or 48 h. At these times, the culture medium was used for determination of PRL content and beta-glucuronidase activity, and the cells were used for determination of DNA content and level of beta-glucuronidase activity or for electron microscopy. Treatment with 10(-6) M chloroquine resulted in 20-40% inhibition of PRL release (maximum inhibition at any dose), no change in the total amount of beta-glucuronidase activity, and a number of ultrastructural changes in the Golgi region consistent with an accumulation of chloroquine within the cisternae and immature granules. The effects of chloroquine on Golgi morphology were unaltered by cotreatment with 50 micrograms/ml cycloheximide, and chloroquine had no affect on PRL synthesis. These results are consistent with an adverse effect of chloroquine on packaging of PRL into immature granules in the Golgi apparatus, without any effect on the release of mature secretory granules.
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PMID:Chloroquine affects prolactin secretion and Golgi morphology in the mammotroph. 669 60

The content of dopamine (DA) and the activity of beta-glucuronidase (a marker for lysosomal enzymes) in the anterior pituitary and the concentration of PRL in serum were determined in male rats that were treated with a variety of drugs that influence the release, storage, or actions of DA. Drugs that increase DA in hypophysial portal blood (amphetamine, methylphenidate and L-dopa) increased DA content, decreased PRL secretion, and had no effect on lysosomal enzyme activity. Drugs that activate DA receptors in the anterior pituitary (apomorphine and bromocriptine) decreased serum PRL but had no effect on DA content or lysosomal enzyme activity. Drugs that decrease DA in the hypophysial portal blood (alpha-methyltyrosine, gamma-butyrolactone, and reserpine) or block DA receptors (haloperidol) increased PRL secretion and decreased DA content and lysosomal enzyme activity. These results suggest that there is no obvious relationship between anterior pituitary DA content and PRL secretion. In addition, lysosomal enzyme activity is not stimulated by increasing the concentration of DA or activating DA receptors in the anterior pituitary, but lysosomal enzyme activity does appear to be tonically stimulated by DA in the control animals since decreasing DA concentrations or receptor activation in the anterior pituitary decreases beta-glucuronidase activity. This latter proposal was confirmed by the demonstration that apomorphine reduced the alpha-methyltyrosine-induced increase in serum PRL and prevented the decrease in anterior pituitary DA content and beta-glucuronidase activity. Furthermore, pretreatment with bromocriptine and L-dopa blocked both the increase in serum PRL concentration and the decrease in anterior pituitary DA content induced by alpha-methyltyrosine and gamma-butyrolactone. On the other hand, bromocriptine and L-dopa blocked the increase in serum PRL concentration but not the reduction in anterior pituitary DA content caused by reserpine, indicating that reserpine has a direct action on DA storage mechanisms in the anterior pituitary. These data suggest that the ability of DA to inhibit PRL secretion and the incorporation of DA into the anterior pituitary are not causally related.
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PMID:Pharmacological manipulation of anterior pituitary dopamine content in the male rat: relationship to serum prolactin concentration and lysosomal enzyme activity. 674 64

The degree of endocrine activity by rat pituitary lactotrophs was manipulated and the lysosomal involvement in the release and intracellular degradation of PRL was monitored by concomitant assays of acid phosphatase, beta-glucuronidase, dipeptidyl peptidases I and II, and nonspecific esterases in the anterior lobe. The in vitro release of PRL by cell cultures was inhibited by 0.5 or 1.5 microM bromocriptine during 24 or 72 h of incubation and by 0.75 microM for 4 h. Long term treatment caused a 40% reduction in the total PRL content of cells and media; however, after 4 h of bromocriptine treatment, no reduction in PRL content was found. TRH (10 ng/ml) in medium for 4 h increased PRL release, whereas it produced intracellular hormone depletion. In vitro treatment of anterior lobes of diestrous rats with 1 microM dopamine decreased PRL release by 50%. No changes in lysosomal enzyme activities were observed after the inhibition of release or stimulation of the in vitro secretion of PRL. Haloperidol (2.5 mg/kg BW) caused a 90% increase in serum PRL concentrations in diestrous rats 1 h after sc injection. alpha-Methyl-p-tyrosine (200 mg/kg BW, ip) stimulated in vivo PRL secretion, monitored 1, 4, and 24 h after drug administration. The administration of 100 micrograms/rat bromocriptine for 3 consecutive days, a single dose of 100 micrograms/rat polyestradiol phosphate, and their combination resulted in the expected changes in PRL production in female rats. These in vivo treatments failed to alter lysosomal enzyme activities in the anterior pituitary. These findings suggest that the release, intracellular accumulation, or depletion of PRL occurred without concomitant changes in lysosomal enzyme activity in the anterior pituitary. We suggest that the system of lysosome-dependent hormone degradation may involve more specific enzymes than those monitored to date.
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PMID:Is there a direct correlation between the activities of various lysosomal enzymes and prolactin secretion in the rat anterior pituitary? 684 58

The effects of dopamine on PRL secretion and lysosomal enzyme activity in anterior pituitary tissue from rats selected during various stages of the estrous cycle were examined under in vitro conditions. During the estrous cycle, there was a marked variation in the capacity of dopamine to stimulate the activity of the lysosomal enzyme beta-glucuronidase in the anterior pituitary gland. Moreover, this variation in the responsiveness of pituitary tissue to the stimulatory action of dopamine on beta-glucuronidase activity was accompanied by a similar variation in the responsiveness of the tissue to the inhibitory action of dopamine on PRL release. Anterior pituitary glands from diestrous rats were the most sensitive to the actions of dopamine on beta-glucuronidase activity and PRL release, whereas glands from estrous animals were the least sensitive. Ovariectomy on the day of diestrus prevented the decline in the responsiveness of the anterior lobe to the actions of dopamine normally seen 2 days later (on the presumptive day of estrus). On the other hand, when animals were treated with estradiol benzoate during the 2 days after ovariectomy, the responsiveness of the pituitary tissue to dopamine was markedly suppressed and was similar to that of tissue from estrous rats. When rats were treated with progesterone during the 2 days after ovariectomy, the responsiveness of the anterior lobe to dopamine was similar to that in ovariectomized controls. It is suggested that the decrease in the responsiveness of the anterior pituitary gland to the actions of dopamine on lysosomal enzyme activity and PRL release that occurs between diestrus and estrus is estrogen mediated. It is also suggested that the ability of estrogen to antagonize the inhibitory effect of dopamine on PRL release may be mediated through an estrogen-induced reduction in the capacity of dopamine to stimulate lysosomal enzyme activity in the anterior pituitary gland.
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PMID:Estrogen alters the responsiveness of the anterior pituitary gland to the actions of dopamine on lysosomal enzyme activity and prolactin release. 746 Aug 50

Malate synthase is a glyoxysome-specific enzyme. The carboxy-terminal tripeptide of the enzyme is Ser-Arg-Leu (SRL), which is known to function as a peroxisomal targeting signal in mammalian cells. To analyze the function of the carboxy-terminal amino acids of pumpkin malate synthase in plant cells, a chimeric gene was constructed that encoded a fusion protein which consisted of beta-glucuronidase and the carboxyl terminus of the enzyme. The fusion protein was expressed and accumulated in transgenic Arabidopsis that had been transformed with the chimeric gene. Immunocytochemical analysis of the transgenic plants revealed that the carboxy-terminal five amino acids of pumpkin malate synthase were sufficient for transport of the fusion protein into glyoxysomes in etiolated cotyledons, into leaf peroxisomes in green cotyledons and in mature leaves, and into unspecialized microbodies in roots, although the fusion protein was no longer transported into microbodies when SRL at the carboxyl terminus was deleted. Transport of proteins into glyoxysomes and leaf peroxisomes was also observed when the carboxy-terminal amino acids of the fusion protein were changed from SRL to SKL, SRM, ARL or PRL. The results suggest that tripeptides with S, A or P at the -3 position, K or R at the -2 position, and L or M at the carboxyl terminal position can function as a targeting signal for three kinds of plant microbody.
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PMID:Transport of chimeric proteins that contain a carboxy-terminal targeting signal into plant microbodies. 877 80