Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: EC:3.4.24.3 (collagenase)
 18,340 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

This investigation was initiated to characterize the stimulation of insulin secretion by phenazine methosulfate (PMS). Islets of Langerhans, isolated by the collagenase method from normal rats and rats pre-injected with either streptozotocin or 6-aminonicotinamide, were exposed to PMS under various experimental conditions and insulin secretion in response to PMS, glucose and pyridine nucleotides was determined. Insulin releasing action of PMS was dose-, time- and temperature-related, occurred in the absence of glucose, and was inhibited by epinephrine, but not by mannoheptulose. In the perifusion system, the pattern of response induced by PMS was spike-like release reaching a maximum in 5 min and declining rapidly to half-maximal value in 10 min. After exposure of islets to beta-cytotoxin either in vivo or in vitro, complete reversal of the cytotoxic effect was obtained with PMS which induced release of insulin in both normal and beta-cytotoxin islets pre-treated. It is concluded that islets depleted of coenzymes could still secrete insulin in response to a reactive proton donor, which might act by substituting for coenzymes and that the immediate action of beta-cytotoxins does not completely arrest the secretory mechanisms in islets of Langerhans.
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PMID:The characterization of phenazine methosulfate stimulated insulin secretion. 295 17

The metabolism of labeled glucose by collagenase-dispersed bovine parathyroid cells was examined. When the medium calcium ion concentration was increased to 2.0 mM, the rate of 14CO2 release from [1-14C]glucose was increased 169 +/- 45% compared with the rate of 0.5 mM calcium. There was no significant change in the rate of 14CO2 release from [6-14C]glucose by this maneuver. The greatest increase in 14CO2 release and decrease in parathyroid hormone secretion occurred between medium calcium ion concentrations of 0.5-1.5 mM. This difference in the metabolism of glucose represents a true increase in hexose shunt activity because the incorporation of label from either [1-14C]- or [6-14C]glucose into parathyroid tissue lipids was equal. This suggests equilibration of label at the level of triose-phosphates. The increase in hexose shunt activity was not due to a calcium-mediated increase in glucose uptake because calcium changes did not affect 2-[3H]deoxyglucose transport by the cells. Phenazine methosulfate added to cells incubated at 0.5 mM calcium selectively increased hexose shunt activity in a dose-dependent manner (91 +/- 33% overall) and concomitantly inhibited parathyroid hormone secretion 65% overall at 0.5 mM calcium. The compound 6-aminonicotinamide inhibited hexose shunt activity but could not overcome the inhibition of hormone secretion at 2.0 mM calcium. A decrease in protein biosynthesis cannot fully explain the inhibition of hormone secretion by calcium or phenazine methosulfate because [3H]-leucine incorporation into total cell protein was not as affected as secretion.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:Role of hexose monophosphate shunt in parathyroid hormone secretion. 641 80

The intranephron distribution of two major cysteine S-conjugate beta-lyases was determined in order to clarify the role of these enzymes in promoting the nephrotoxicity associated with certain halogenated xenobiotics. Various nephron segments [i.e., glomerulus, early, middle, and terminal portions of the proximal tubule (S1, S2, and S3 respectively), the thick ascending limb, the distal tubule, and the collecting tubule] were isolated by microdissection from collagenase-treated rat kidneys. Each segment was dissected in Hanks' solution, solubilized with Triton X-100, and applied to a micropolyacrylamide gel constructed with a continuous gradient. The gels were subjected to electrophoresis and then incubated in the dark in a solution containing S-(1,2 dichlorovinyl)-L-cysteine (DCVC), a sodium alpha-keto-gamma-methiolbutyrate, phenazine methosulfate, and nitro-blue tetrazolium. The position of cysteine S-conjugate beta-lyase- and L-amino acid oxidase activities in the gels was revealed by the presence of blue formazen dye bands. The relative intensities of the bands were determined by optical scanning with a microdensitometer. Three bands were detected: band I (M(r) approximately 330,000) corresponds to a recently described high M(r) cysteine S-conjugate beta-lyase whereas band III (M(r) approximately 90,000) corresponds to a lower M(r) cysteine S-conjugate beta-lyase (identical to cytosolic glutamine transaminase K). Band II (M(r) approximately 240,000) corresponds to L-amino acid oxidase (a unique activity of the B isoform of rat kidney L-hydroxy acid oxidase). beta-lyase activity with DCVC as substrates was detected in the S1, S2, and S3 segments of the nephron but not in other regions of the kidney. The activity was in the order: S2 = S3 > S1. In another series of experiments, rats were killed 24 h after treatment with hexachloro- 1,3-butadiene (HCBD). In whole kidney homogenates the relative intensity of band III (per 22.2 micrograms tissue wet weight) after a 30 min incubation was induced significantly (by 50%), but the relative intensities of the other two bands were unchanged. On the other hand, in proximal tubules isolated from HCBD-treated rats the relative intensities (per 5 mm of nephron) of peak I of S2, peak II of S3, and peak III of S3 were significantly reduced by 28, 33, and 72%, respectively. These findings suggest that the low M(r) beta-lyase is induced by HCBD and that impaired cell function in the segments (especially S3) results in proteins leaking out of the target cells. To examine the relationship between the nephrotoxic effect of HCBD and cysteine S-conjugate beta-lyase activity, the intracellular ATP:protein ratio was quantitated in each nephron segment and in whole kidney homogenates. In HCBD-treated rats the ATP:protein ratio of the S1, S2, and S3 segments was unchanged, decreased by approximately 50%, and increased by approximately 30% respectively. In the kidney homogenates of HCBD-treated rats the ATP content was decreased by 32%. However, the loss of ATP was significantly less when the rats were pretreated with aminooxyacetate (a general inhibitor of pyridoxal 5'-phosphate-dependent enzymes, including beta-lyase) 1 h before HCBD administration. The results strongly suggest that HCBD is converted to toxic metabolites within the kidney and that this process leads to metabolic derangement and reduction of ATP in susceptible kidney cells.
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PMID:Intranephron distribution of cysteine S-conjugate beta-lyase activity and its implication for hexachloro-1,3-butadiene-induced nephrotoxicity in rats. 904 49

A rate-limiting step of tumor cell metastasis is matrix degradation by active matrix metalloproteinases (MMPs). It is known that reactive oxygen species are involved in tumor metastasis. Sustained production of H(2)O(2) by phenazine methosulfate (PMS) induced activation of pro-MMP-2 through the induction of membrane type 1-MMP (MT1-MMP) expression in HT1080 cells. MMP-2, MMP-9, and tissue inhibitor of metalloproteinase-1 and -2 levels were changed negligibly by PMS. A one time treatment with H(2)O(2) did not induce activation of MMPs. It was also demonstrated that superoxide anions and hydroxyl radicals were not related to PMS action. PMS-induced pro-MMP-2 activation was regulated by the receptor tyrosine kinases, especially the receptors of platelet-derived growth factor and vascular endothelial growth factor, and downstream on the phosphatidylinositol 3-kinase/NF-kappa B pathway but not Ras, cAMP-dependent protein kinase, protein kinase C, and mitogen-activated protein kinases. PMS did not induce pro-MMP-2 activation in T98G and NIH3T3 cells. This may be related to a low level of MT1-MMP, indicating a threshold level of MT1-MMP is important for pro-MMP-2 activation. Furthermore, PMS increased cell motility and invasion but decreased cell-cell interaction. Cell-matrix interaction was not affected by PMS.
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PMID:Sustained production of H(2)O(2) activates pro-matrix metalloproteinase-2 through receptor tyrosine kinases/phosphatidylinositol 3-kinase/NF-kappa B pathway. 1205 32