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PMID:16959573

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Citation

Haigis, MC, Mostoslavsky, R, Haigis, KM, Fahie, K, Christodoulou, DC, Murphy, AJ, Valenzuela, DM, Yancopoulos, GD, Karow, M, Blander, G, Wolberger, C, Prolla, TA, Weindruch, R, Alt, FW and Guarente, L (2006) SIRT4 inhibits glutamate dehydrogenase and opposes the effects of calorie restriction in pancreatic beta cells. Cell 126:941-54

Abstract

Sir2 is an NAD-dependent deacetylase that connects metabolism with longevity in yeast, flies, and worms. Mammals have seven Sir2 homologs (SIRT1-7). We show that SIRT4 is a mitochondrial enzyme that uses NAD to ADP-ribosylate and downregulate glutamate dehydrogenase (GDH) activity. GDH is known to promote the metabolism of glutamate and glutamine, generating ATP, which promotes insulin secretion. Loss of SIRT4 in insulinoma cells activates GDH, thereby upregulating amino acid-stimulated insulin secretion. A similar effect is observed in pancreatic beta cells from mice deficient in SIRT4 or on the dietary regimen of calorie restriction (CR). Furthermore, GDH from SIRT4-deficient or CR mice is insensitive to phosphodiesterase, an enzyme that cleaves ADP-ribose, suggesting the absence of ADP-ribosylation. These results indicate that SIRT4 functions in beta cell mitochondria to repress the activity of GDH by ADP-ribosylation, thereby downregulating insulin secretion in response to amino acids, effects that are alleviated during CR.

Links

PubMed Online version:10.1016/j.cell.2006.06.057

Keywords

Adenosine Diphosphate Ribose/metabolism; Amino Acids/pharmacology; Animals; Caloric Restriction; Cell Line, Tumor; Down-Regulation; Glucose/pharmacology; Glutamate Dehydrogenase/genetics; Glutamate Dehydrogenase/metabolism; Glutamine/pharmacology; Humans; Insulin/metabolism; Insulin-Secreting Cells/drug effects; Insulin-Secreting Cells/enzymology; Islets of Langerhans/drug effects; Islets of Langerhans/enzymology; Mice; Mice, Knockout; Mitochondria/enzymology; NAD/metabolism; Protein Processing, Post-Translational; RNA, Small Interfering/genetics; RNA, Small Interfering/metabolism; Sirtuin 1; Sirtuins/genetics; Sirtuins/metabolism; Transfection

Significance

Annotations

Gene product Qualifier GO ID GO term name Evidence Code with/from Aspect Notes Status


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References

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