Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UNIPROT:P01275 (glucagon)
 26,492 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The acidic glucagon-degrading activity of hepatic endosomes has been attributed to membrane-bound forms of cathepsins B and D. Endosomal lysates processed full-length nonradiolabeled glucagon to 32 different peptides that were identified by amino acid analysis and full-length sequencing. These indicated C-terminal carboxypeptidase, endopeptidase as well as N-terminal tripeptidyl-aminopeptidase activities in endosomes. Glucagon proteolysis was inhibited 95% by E-64 and pepstatin A, inhibitors of cathepsins B and D, respectively. This was confirmed by the pH 6-dependent chemical cross-linking of [125I]iodoglucagon to a polypeptide of 30 kDa, which was immunodepleted by polyclonal anti-cathepsin B antibody, and the removal of greater than 80% of glucagon-degrading activity by polyclonal antibodies to cathepsins B and D. By similar criteria, insulin-degrading enzyme was ruled out as a candidate enzyme for endosomal proteolysis of glucagon. Lysosomal contamination was unlikely since all forms of cathepsin B in endosomes, i.e. the major 45-kDa inactive precursor as well as the lesser amounts of the 32- and 28-kDa active forms, were tightly bound to endosomal membranes. Furthermore the mature 29-kDa single-chain and 22-kDa heavy-chain forms of cathepsin L were undetectable in endosomes, although high levels of the 37-kDa proform were observed. Membrane association of the cathepsins B and D was not to the mannose 6-phosphate receptor since association was unaffected by mannose 6-phosphate and/or EDTA, thereby indicating a distinct endosomal receptor. Hence, a pool of active cathepsins B and D as well as a poorly defined tripeptidyl aminopeptidase is maintained in endosomes by selective membrane retention. These hydrolases degrade glucagon internalized into liver parenchyma early in endocytosis.
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PMID:Proteolysis of glucagon within hepatic endosomes by membrane-associated cathepsins B and D. 779 82

The activities of cathepsin B, L, J and H in rat liver were significantly increased by starvation if compared with normal diet rats. Furthermore, the activity of cathepsin L increased with glucagon treatment, and the activities of cathepsin L and H decreased significantly with insulin treatment. The changes in cathepsin B and J activities showed the same tendencies as those of cathepsin L and H, but the differences were not statistically significant. The changes in the activities of cathepsin B and L on starvation corresponded with the changes of enzyme protein amounts judged from Western blotting analysis. The levels of the lysosomal cysteine proteinases and amino acid deaminases in the liver changed in parallel with the hormonal and dietary conditions. The increases of alanine amino transferase activity (AAT) started from a much earlier stage than those of cathepsins under the starvation condition. Although administration of prednisolone caused marked induction of the deamination enzymes such as AAT, the levels of cathepsins in the liver were not changed.
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PMID:Hormonal and dietary regulation of lysosomal cysteine proteinases in liver under gluconeogenesis conditions. 892 90

The protective effects of glucagon on the exocrine pancreas were investigated in rats with a closed duodenal loop (CDL). A CDL in rats caused marked hyperamylasemia, pancreatic edema and pancreatic histological damage such as acinar cell vacuolization and interstitial edema. A CDL also caused redistribution of the lysosomal enzyme, cathepsin B, from the lysosomal fraction to the zymogen fraction as well as the activation of trypsinogen in pancreatic tissue. Moreover, a CDL caused a marked motality rate (40% at 48 h). However, treatment with glucagon at a dose of 1.0 mg/kg (subcutaneous injection) every 8 h (3 times) significantly inhibited these pancreatic injuries, improving the survival rate (95% at 48 h). These results indicate the important role of lysosomal enzymes in the pathogenesis of severe acute pancreatitis, and also suggest the possible usefulness of glucagon in the treatment of clinical pancreatitis.
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PMID:Glucagon ameliorates pancreatic subcellular redistribution of lysosomal enzyme in rats with acute pancreatitis of closed duodenal loop. 994 62

Plant cathepsin B-like cysteine protease (CBCP) plays a role in disease resistance and in protein remobilization during germination. The ability of animal cathepsin B to function as a dipeptidyl carboxypeptidase has been attributed to the presence of a dihistidine (His110-His111) motif in the occluding loop, which represents a unique structure of cathepsin B. However, a dihistidine motif is not present in the predicted sequence of the occluding loop of plant CBCP, as determined from cDNA sequence analysis, and the loop is shorter. In an effort to investigate the enzymatic properties of plant CBCP, which possesses the unusual occluding loop, we have purified CBCP from the cotyledons of daikon radish (Raphanus sativus) by chromatography through Sephacryl S-200, DEAE-cellulose, hydroxyapatite and organomercurial-Sepharose. The molecular mass of the enzyme was estimated to be 28 kDa by SDS/PAGE under reducing conditions. The best synthetic substrate for CBCP was t-butyloxycarbonyl Leu-Arg-Arg-4-methylcoumaryl 7-amide, as is the case with human cathepsin B. However, the endopeptidase activity of CBCP towards glucagon and adrenocorticotropic hormone showed broad cleavage specificity. Human cathepsin B preferentially cleaves model peptides via its dipeptidyl carboxypeptidase activity, whereas daikon CBCP displays both endopeptidase and exopeptidase activities. In addition, CBCP was found to display carboxymonopeptidase activity against the substrate o-aminobenzoyl-Phe-Arg-Phe(4-NO(2)). Daikon CBCP is less sensitive (1/7000) to CA-074 than human cathepsin B. Expression analysis of CBCP at the protein and RNA levels indicated that daikon CBCP activity in cotyledons is regulated by post-transcriptional events during germination.
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PMID:Purification and characterization of cathepsin B-like cysteine protease from cotyledons of daikon radish, Raphanus sativus. 1895 67

The molecular pathogenesis of gastroenteropancreatic neuroendocrine tumors is largely unknown. We hypothesize that gastroenteropancreatic neuroendocrine tumors are heterogeneous with regard to these signaling pathways and these differences could have a significant impact on the outcome of clinical trials. We selected 120 well-differentiated neuroendocrine tumors including tumors originating in pancreas (n=74), ileum (n=31), and rectum (n=15). Immunohistochemistry was performed on tissue microarrays using the following antibodies: NOTCH1, HES1, HEY1, pIGF1R, and FGF2. Gene profiling study was performed by using human genome U133A 2.0 array and data were analyzed. The gene profiling results were selectively confirmed by using quantitative reverse-transcription PCR. Initial immunohistochemical analysis showed NOTCH1 was uniformly expressed in rectal neuroendocrine tumors (100%), a subset of pancreatic neuroendocrine tumors (34%), and negative in ileal neuroendocrine tumors. Similarly, a downstream target of NOTCH1, HES1 was preferentially expressed in rectal neuroendocrine tumors (64%), a subset of pancreatic neuroendocrine tumors (10%), and uniformly negative in ileal neuroendocrine tumors. Messenger RNAs for NOTCH1, HES1, and HEY1 were 2.32-, 2.44-, and 2.39-folds, respectively, higher in rectal neuroendocrine tumors as compared with ileal neuroendocrine tumors. Global gene expression profiling showed 95 genes were differentially expressed in small intestinal vs rectal neuroendocrine tumors, with changes as high as 50-fold. These genes were concentrated in several signal transduction pathways including cancer endocrine pathway and cell growth/proliferation pathway. The differential expression of selected genes including ISL LIM homeobox 1, cathepsin B, glucagon, and tryptophan hydroxylase 1 were confirmed by qPCR and immunohistochemistry. Our results confirm the heterogeneity in signaling pathways of gastroenteropancreatic neuroendocrine tumors. NOTCH1 inhibitors are unlikely to provide benefit in ileal neuroendocrine tumors; conversely, their efficacy in rectal neuroendocrine tumors needs further study. Further analysis of signaling pathways is critical for designing clinical trials in gastroenteropancreatic neuroendocrine tumors.
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PMID:Heterogeneity in signaling pathways of gastroenteropancreatic neuroendocrine tumors: a critical look at notch signaling pathway. 2291 66


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