Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: EC:4.6.1.2 (guanylate cyclase)
 8,497 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Streptozotocin (STZ) is selectively toxic to insulin-secreting beta-cells of pancreatic islets and induces impairment of islet glucose oxidation and of glucose-induced insulin secretion. Similar effects are induced by Interleukin-1 (IL-1), and the deleterious effects of IL-1 on islets appear to be mediated by nitric oxide (NO). STZ contains a nitroso moiety and may liberate NO by processes analogous to those for the NO-releasing drug nitroprusside. NO is rapidly transformed to nitrite in aqueous solution, and NO activates heme-containing enzymes such as guanylyl cyclase and inhibits iron-sulfur enzymes such as mitochondrial aconitase. Data presented here indicate that incubation of rat islets with STZ at concentrations that impair insulin secretion results in generation of nitrite, stimulation of islet guanylyl cyclase and accumulation of cGMP, and inhibition of islet mitochondrial aconitase activity to a degree similar to that achieved by IL-1. Effects of STZ on beta-cells may be mediated by local liberation of NO from STZ within islets.
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PMID:Biochemical evidence for nitric oxide formation from streptozotocin in isolated pancreatic islets. 790 59

Treatment of streptozotocin (ST), tumor necrosis factor-alpha (TNF-alpha), and interleukin-1beta (IL-1beta) resulted in destroying insulin-secreting beta-cells of pancreatic islets and impairment of islet glucose oxidation and glucose-induced insulin secretion. IL-1beta and TNF-alpha inhibited insulin release and glucose utilization and oxidation. It was shown that the inhibitory effects of ST, IL-1beta, and TNF-alpha were due to impaired glucokinase activity. Glucokinase activity was severely impaired by ST, IL-1beta, and TNF-alpha treatments, as confirmed by assaying enzymes and nucleotides associated with glycolysis and glucose oxidation. On the other hand, nitric oxide was a factor of the deleterious effects of IL-1beta, TNF-alpha, and ST on pancreatic islets. Incubation of mouse pancreatic islets with ST at various concentrations of impairing insulin secretion resulted in generation of nitrite, stimulation of islet guanylyl cyclase and accumulation of cGMP, and inhibition of pancreatic islet mitochondrial aconitase activity to degree similar to those raised by IL-1beta and TNF-alpha. When the effects of IL-1beta and TNF-alpha on the gene expression of pancreatic GLUT2 and glucokinase were examined, the level of GLUT2 and glucokinase mRNA in pancreatic islets was significantly decreased. This suggested that IL-1beta and TNF-alpha downregulate gene expression of GLUT2 and glucokinase in pancreatic beta-cells.
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PMID:Inhibitory effects of streptozotocin, tumor necrosis factor-alpha, and interleukin-1beta on glucokinase activity in pancreatic islets and gene expression of GLUT2 and glucokinase. 998 30

Treatment of rat islets with the cytokine IL-1 results in the inhibition of mitochondrial function and insulin secretion, events that are mediated by beta-cell expression of iNOS [inducible nitric oxide (NO) synthase] and production of NO. beta-Cells recover from the inhibitory actions of NO, produced following 24 h incubation with IL-1, on islet oxidative metabolism and insulin secretion if iNOS enzymatic activity is inhibited and the islets are cultured (in the presence of IL-1 and iNOS inhibitors) for a brief period of 8 h. Islet recovery from cytokine- and NO-mediated damage is an active process that requires new gene expression, and NO itself is one activator of this recovery process. In this study, the mechanism by which NO stimulates islet recovery has been examined. Incubation of rat islets or RINm5F cells with the NO donor compound, sodium (Z)-1(N,N-diethylamino) diazen-1-ium-1,2-diolate (DEA-NO) for 1 h results in a 60% inhibition of mitochondrial aconitase activity. beta-Cells completely recover aconitase activity if the cells are washed to remove the NO donor compound and incubated for an additional 5 h in the absence of DEA-NO. The recovery of mitochondrial aconitase activity correlates with a 4-fold increase in cyclic GMP accumulation and is prevented by the inhibition of guanylate cyclase. The recovery of aconitase activity also correlates with the activation of members of the MAPKs, p38, c-Jun N-terminal kinase (JNK) and ERK, and the activation p38 and JNK is attenuated by inhibition of guanylate cyclase. ERK and p38 do not appear to participate in the recovery process as selective inhibition of these kinases fails to prevent recovery of aconitase activity; however, transduction of beta-cells with a dominant negative mutant JNK prevents beta-cell recovery from NO-mediated damage. These findings support a role for guanylate cyclase and JNK in the recovery of beta-cells from NO-mediated damage.
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PMID:Role for c-Jun N-terminal kinase in beta-cell recovery from nitric oxide-mediated damage. 1286 20