• BMB Reports
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• v.45 no.8
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• pp.458-463
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• 2012

We investigated the mechanisms involved in KHG26377 regulation of glutamate dehydrogenase (GDH) activity, focusing on the roles of SIRT4 and SIRT3. Intraperitoneal injection of mice with KHG26377 reduced GDH activity with concomitant repression of glucose-induced insulin secretion. Consistent with their known functions, SIRT4 ribosylated GDH and reduced its activity, and SIRT3 deacetylated GDH, increasing its activity. However, KHG26377 did not affect SIRT4-mediated ADP-ribosylation/inhibition or SIRT3-mediated deacetylation/activation of GDH. KHG26377 had no effect on SIRT4 protein levels, and did not alter total GDH, acetylated GDH, or SIRT3 protein levels in pancreatic mitochondrial lysates. These results suggest that the mechanism by which KHG26377 inhibits GDH activity and insulin secretion does not involve ADP-ribosylation of GDH by SIRT4 or deacetylation of GDH by SIRT3.

• BMB Reports
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• v.43 no.4
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• pp.245-249
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• 2010

GDH has been known to be related with hyperinsulinism-hyperammonemia syndrome. We have screened new drugs with a view to developing effective drugs modulating GDH activity. In the present work, we investigated the effects of a new drug, KHG26377 on glutamate formation and GDH activity in cultured rat islets. When KHG26377 was added to the culture medium for 24 h prior to kinetic analysis, the $V_{max}$ of GDH was decreased by 59% whereas $K_m$ is not significantly changed. The concentration of glutamate decreased by 50% and perfusion of islets with KHG26377 reduced insulin release by up to 55%. Our results show that KHG26377 regulates insulin release by inhibiting GDH activity in primary cultured islets and support the previous studies for the connection between GDH activity and insulin release. Further studies are required to determine in vivo effects and pharmacokinetics of the drug.