Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: UMLS:C0011849 (diabetes)
 277,896 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The disappearance rate of intravenously injected insulin was investigated in the serum of 30 women during the third trimester of pregnancy and 6 to 8 weeks post partum, in order to determine whether pregnancy has an influence on insulin kinetics in human subjects. Both women with unimpaired glucose tolerance and those with latent diabetes were included in this study. The disappearance rate of exogenous serum insulin in pregnancy was characterized by a two-compartment model. Multivariate analyses of variance were used to determine whether the estimated parameters of this model during pregnancy differ from those obtained after the puerperium and whether the insulin kinetics are altered when carbohydrate metabolism is disturbed. The kinetics of insulin during pregnancy did not differ from those after pregnancy. Thus, hyperinsulinemia observed in pregnancy cannot be explained by a change in the insulin kinetics. It appears improbable that the insulin-degrading enzyme activities of the placenta participate in degradation of insulin circulating in the maternal blood. A connection between the decline of glucose tolerance during pregnancy and the kinetics of exogenous insulin could not be found.
 ...
PMID:Influence of pregnancy on the kinetics of insulin. 114 34

The degradation of native and 125I-labeled human insulin (HI) was examined in the cytosolic fraction of human, monkey, and rat liver. The purpose of these studies was to provide a species comparison of the interaction of insulin-degrading enzyme (IDE) and protein disulfide isomerase (PDI) in the degradation of HI. Western-blot analysis with monoclonal antibodies indicated the presence of both IDE and PDI in the cytosolic fraction of human and monkey liver. In contrast, rat liver cytosol contained, detectable levels of IDE only. A species comparison of metabolic profiles was performed by fractionating peptide products with reversed-phase high-performance liquid chromatography. After a 60-min incubation, human liver cytosol degraded unlabeled HI into three major products. Two of these peptides coeluted with the products of the incubation of HI with purified rat liver PDI. The three peptides were isolated and determined by NH2-terminal sequence analysis to be intact A chain, B chain, and des(Phe1)-B chain. Human liver cytosol also formed 125I-A chain and 125I-B chain as major products when specifically labeled 125I-HI isomers were used as substrate. Significant proteolytic degradation was observed only when reactions with human liver cytosol were supplemented with Mn2+. In contrast, monkey and rat liver cytosol proteolytically degraded 125I-HI isomers to small peptide fragments. The rat and monkey metabolic profiles were similar to each other and to that observed with Mn(2+)-supplemented human liver cytosol. Proteolysis in monkey and rat was sensitive to inhibition by EDTA.(ABSTRACT TRUNCATED AT 250 WORDS)
Diabetes 1992 Apr
PMID:Mechanisms involved in degradation of human insulin by cytosolic fractions of human, monkey, and rat liver. 160 78

The nature of insulin degradation within endosomes was studied in vitro. Radiolabeled insulin was perfused into rat liver via the portal vein, and insulin-containing endosomes were prepared by differential centrifugation. The endosomes were incubated in various buffers, and hormone degradation was monitored by Sephadex G-50 chromatography and high-performance liquid chromatography (HPLC). Endosomes incubated in simple imidazole or HEPES (pH 7.4) buffers rapidly degraded insulin to intermediate- and then to low-molecular-weight products that were lost from the vesicles. HPLC analysis of insulin-sized material showed the products to be the same as those produced by intact cells. The endosomes did not acidify in these buffers (as assessed by the acridine orange method), and ATP had no effects. When the endosomes were incubated in a chloride-containing buffer, degradation was greatly inhibited, and acidification did not occur. Both insulin degradation and acidification were activated when Mg-ATP was added to this buffer system. HPLC analysis of the products generated in this system revealed not only typical cellular products but additional less hydrophobic products. Western-blot analysis of endosomal protein with anti-insulin-degrading enzyme antibody showed this enzyme to be present. In conclusion, isolated endosomes rapidly and completely degrade insulin through products that are typical of cellular degradation without requiring acidification. Chloride-containing buffers inhibit endosomal degradation, which is reversed by Mg-ATP, but this system does not mimic cellular degradation. At least one of the enzymes responsible for insulin degradation is insulin-degrading enzyme.
Diabetes 1991 Apr
PMID:Degradation of intraendosomal insulin by insulin-degrading enzyme without acidification. 201 43

Five monoclonal antibodies specific for glutathione-insulin transhydrogenase were characterized. None of the monoclonal antibodies cross-reacted with another insulin-degrading enzyme, neutral thiopeptidase. The isotype of four antibodies was IgG1 and of the fifth IgG2b. Affinity studies, competitive binding studies and immunoblot analysis of CNBr and trypsin cleavage products of glutathione-insulin transhydrogenase demonstrated that the four IgG1 antibodies were directed to an epitope of the enzyme which was distinct from the epitope recognized by the IgG2b antibody. Inhibition studies indicated that each monoclonal antibody, when added singly to glutathione-insulin transhydrogenase, was unable to inhibit the insulin-degrading activity of the enzyme. However, when monoclonal antibodies directed against separate epitopes of glutathione-insulin transhydrogenase were presented together (i.e., the IgG2b with any one of the four IgG1 antibodies), a loss in enzymatic activity was noted. Immunoblot analysis of rat organ extracts with the IgG1 antibodies demonstrated one immunoreactive protein band of Mr 56,000 in all tissues examined (liver, fat, pancreas and kidney) except the spleen, which demonstrated two immunoreactive protein bands of Mr 56,000 and 51,000. The same immunoblots, when probed with the IgG2b antibody, demonstrated the same immunoreactive protein banding pattern as above plus an additional immunoreactive protein band of Mr 67,000 in all tissues. Studies with spleen extracts from steptozotocin-induced diabetic rats demonstrated that there was a loss of the 51,000 immunoreactive band in diabetes. This 51,000 protein was restored upon insulin treatment of the diabetic rats and nullified upon concomitant administration of cycloheximide or actinomycin D with insulin. Immunoblots of human liver, adipose and skeletal muscle extracts indicated that each monoclonal antibody cross-reacted with the human form of the enzyme which had a molecular weight of Mr 63,000; a second minor immunoreactive band of 67,000 was detected with the IgG2b antibody. The physiological significance of additional molecular forms of the enzyme (i.e., 67,000 and 51,000) remains to be determined.
 ...
PMID:Characterization and application of monoclonal antibodies directed to separate epitopes of glutathione-insulin transhydrogenase. 243 25

An insulin-degrading enzyme has been purified from human erythrocytes. This enzyme degraded 125I-labeled insulin-like growth factor I (IGF-I) more slowly than 125I-IGF-II and degraded IGF-II more slowly than 125I-insulin. The time course of 125I-insulin degradation suggested the presence of intermediates, each of which was itself shown to be a substrate for the enzyme. One of these intermediates appeared to be made up entirely of B-chain residues and had HisB10 as its NH2-terminal. The final major radiolabeled degradation product of A14-[125I]monoiodoinsulin was a peptide with TyrA14 at the A-chain NH2 terminal. This peptide could be reduced with dithiothreitol, suggesting that it contained amino acid residues from both A- and B-chains. It was partially precipitated by trichloroacetic acid and anti-insulin antibody but bound poorly to IM-9 lymphocytes. The final major degradation product of B26-[125I]monoiodoinsulin was a peptide whose NH2-terminal was TyrB26 and could not be reduced by dithiothreitol. It was partially precipitated by anti-insulin antibody but was precipitated poorly, if at all, by trichloroacetic acid and bound poorly to IM-9 lymphocytes. The results show that this enzyme degraded insulin by sequential cleavage of peptide bonds on both A- and B-chains. We identified LeuA13-TyrA14, SerB9-HisB10, and PheB25-TyrB26 as three of the bonds that are cleaved.
Diabetes 1989 Feb
PMID:Degradation of insulin and insulin-like growth factors by enzyme purified from human erythrocytes. Comparison of degradation products observed with A14- and B26-[125I]monoiodoinsulin. 264 37

An insulin-degrading enzyme (IDE) was purified from the cytosol of human erythrocytes via the use of ammonium sulfate precipitation and chromatography on columns composed of DEAE-Sephadex, pentylagarose, hydroxylapatite, chromatofocusing resins, and Ultrogel AcA-34. The final preparation was purified greater than 50,000-fold and exhibited a single protein band of Mr = 110,000 on reduced sodium dodecyl sulfate (SDS)-polyacrylamide gel electrophoresis. Cross-linking of 125I-labeled insulin to the enzyme preparation labeled a protein of the same molecular weight, indicating that this band was in fact the enzyme. Intact insulin, insulin B chain, and glucagon inhibited this cross-linking half-maximally at concentrations of 0.1, 1, and 1.5 microM, respectively. Under nondenaturing conditions, the enzyme had an Mr = 300,000, suggesting that the enzyme may exist under physiological conditions as a dimer or timer. The purified enzyme was inhibited by both sulfhydrylmodifying reagents and chelating agents, indicating that a free thiol and metal were both required for the activity of the enzyme. The purified enzyme was found to degrade physiological concentrations of intact insulin more rapidly than insulin B chain, although at high substrate concentrations (greater than 1 microM) the enzyme degraded B chain to a greater extent. Additional characteristics of the enzyme were a pl of 5.2 and a pH optimum of 7.0. These properties of the red blood cell (RBC) enzyme were very similar to those reported for IDEs from other tissues. Moreover, a polyclonal antiserum to the IDE from skeletal muscle was found to recognize the RBC enzyme.
Diabetes 1986 Jun
PMID:Purification and characterization of insulin-degrading enzyme from human erythrocytes. 351 22

The activity of the insulin-degrading enzyme neutral cysteine proteinase (EC 3.4.22.11, insulinase) was studied in adipose tissue and in liver of nondiabetic, streptozotocin-diabetic, and insulin-treated diabetic rats. Proteinase activity was found to be significantly decreased during diabetes and was restored to near normal levels in both tissues following insulin treatment. The insulin-mediated increase of proteinase activity in both tissues was partially or completely blocked by actinomycin D (an inhibitor of RNA synthesis) and by cyclohexamide (an inhibitor of protein synthesis). Kinetic analysis showed that the changes in proteinase activity of both liver and adipose tissues were accompanied by a change in Vmax (i.e., maximal enzyme activity) without a change in Km (i.e., substrate affinity). These data indicate that insulin functions as an inducer for neutral cysteine proteinase in both tissues. These alterations in the proteinase activity paralleled the alterations in the activity of a second insulin-degrading enzyme, glutathione-insulin transhydrogenase in adipose tissue (this paper) and in liver (previously published papers) under the same physiological conditions.
 ...
PMID:Insulin-degrading neutral cysteine proteinase activity of adipose tissue and liver of nondiabetic, streptozotocin-diabetic, and insulin-treated diabetic rats. 355 42

Insulin-degrading enzyme (IDE), which proteolytically degraded insulin with a high degree of specificity, was purified from pig skeletal muscle by ammonium sulfate precipitation, chromatography on Bio-Gel P-200 and DEAE-cellulose, and finally rechromatography on Sephadex G-200 (rechromatography fraction). The enzyme was also purified by affinity chromatography (affinity fraction). Both fractions migrated as a single component at the same position on polyacrylamidegel disc electrophoresis. Antiserum against pig muscle IDE was obtained by immunization of rabbits using the rechromatography fraction. By means of antiserum, it was shown that pig muscle IDE (affinity fraction), rat muscle cytosol-, and membrane-IDE gave a precipitin band of identity in Ouchterlony double-immunodiffusion systems. Quantitative immunoprecipitin data demonstrated that the antiserum inhibited the activities of the above three IDEs compared with normal rabbit serum. These data suggest that the insulin-degrading enzyme from porcine muscle and that from rat muscle have similar immunologic properties. The antiserum described here should be a useful tool for the examination of subcellular distribution and the quantitative analysis of insulin-degrading enzyme. It may also be helpful in determining the physiologic significance of IDE.
Diabetes 1980 Oct
PMID:Immunochemical studies on the insulin-degrading enzyme from pig and rat skeletal muscle. 677 21

Insulin-degrading enzyme (IDE) is a component of a cytosolic complex that includes multicatalytic proteinase (MCP), the major cytoplasmic proteolytic activity. Insulin, the primary substrate for IDE, inhibits the proteolytic activity of the IDE-MCP complex but not of purified MCP. This provides a regulatory role for IDE in cellular proteolysis and a potential mechanism for intracellular insulin action. To examine the specificity and to explore the mechanisms for the IDE-MCP interaction, we studied the functional interaction of a variety of peptides with the complex. Atrial natriuretic peptide (ANP), relaxin, glucagon, proinsulin, and insulin-like growth factor II (IGF-II) bind to and are degraded by IDE. These peptides have significant inhibitory effects on the chymotrypsin-like and trypsin-like MCP catalytic activities but not the peptidyl-glutamyl hydrolyzing activity. A panel of peptides that are not ligands of IDE had no effect. To explore the potential mechanism for the IDE control of MCP activity, dose response curves for insulin-like growth factor I (IGF-I) and IGF-II effects on MCP chymotrypsin-like activity were determined. IGF-II, which (similar to insulin) is a good substrate for IDE, had a substantial inhibitory effect, whereas IGF-I, which is bound but poorly degraded, had little inhibitory activity on MCP. Proinsulin, another ligand of IDE that is tightly bound but poorly degraded, had a partial effect on MCP activity, but inhibited the full insulin effect. These data suggest a requirement for both the binding and degradation of IDE ligands for the full inhibition of MCP. Insulin-sized degradation products, substrates of IDE, also inhibited MCP activity. Further examination of the insulin effect on MCP included kinetic studies. Insulin produced a noncompetitive inhibition of both the chymotrypsin-like and trypsin-like activities of MCP. These data suggest that the insulin-IDE effect on MCP is due to conformational changes in the IDE-MCP complex and provide an intracellular mechanism of action for insulin.
Diabetes 1997 Feb
PMID:Characterization of the insulin inhibition of the peptidolytic activities of the insulin-degrading enzyme-proteasome complex. 900 Jun 94

The signal transduction of the formyl-Met-Leu-Phe (FMLP) receptor in polymorphonuclear leukocytes (PMNLs) from patients with non-insulin-dependent diabetes mellitus (NIDDM) was compared to that of PMNLs obtained from healthy volunteers. According to our previous studies in this group of patients neither the decrease in insulin binding capacity nor the enhanced insulin-degrading enzyme activity was involved. In control PMNLs, 10 nM FMLP induced a pertussis toxin-sensitive increase in phosphatidyl inositol (PI) cleavage and a subsequent Ca2+ signaling from the intracellular pools. On the other hand, the FMLP-induced protein kinase C (PKC) activation and translocation into the membrane could not be detected in these cells via the measurement of 32P incorporation into histone. In contrast, in PMNLs of this special group of patients suffering from NIDDM the FMLP stimulus produced a significantly low increase in PI cleavage and Ca2+ signaling from the intracellular pools. Moreover, in resting PMNLs of these patients with NIDDM, not only the [Ca2+]i but also the membrane-bound PKC activity was found to be significantly increased. In addition, PKC translocation into the cell membrane of diabetic PMNLs could be further triggered with FMLP as judged by the measurement of 32P incorporation into histone. Based on these results, it appears that the signaling of FMLP receptors in PMNLs of some NIDDM patients may have an alternative pathway through Ca2+ influx from extracellular medium, arachidonic acid cascade, and PKC activation.
 ...
PMID:Altered postreceptor signal transduction of formyl-Met-Leu-Phe receptors in polymorphonuclear leukocytes of patients with non-insulin-dependent diabetes mellitus. 943 1


1 2 3 4 5 6 7 8 9 10 Next >>