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Increased nicotinamide nucleotide transhydrogenase levels predispose to insulin hypersecretion in a mouse strain susceptible to diabetes
journal contribution
posted on 2007-01-01, 00:00 authored by Kathryn Aston-MourneyKathryn Aston-Mourney, N Wong, M Kebede, S Zraika, L Balmer, J McMahon, B Fam, J Favaloro, J Proietto, G Morahan, S AndrikopoulosAims/hypothesis Insulin hypersecretion may be an independent predictor of progression to type 2 diabetes. Identifying genes affecting insulin hypersecretion are important in understanding disease progression. We have previously shown that diabetes-susceptible DBA/2 mice congenitally display high insulin secretion. We studied this model to map and identify the gene(s) responsible for this trait.
Methods Intravenous glucose tolerance tests followed by a genome-wide scan were performed on 171 (C57BL/6 × DBA/2) × C57BL/6 backcross mice.
Results A quantitative trait locus, designated hyperinsulin production-1 (Hip1), was mapped with a logarithm of odds score of 7.7 to a region on chromosome 13. Production of congenic mice confirmed that Hip1 influenced the insulin hypersecretion trait. By studying appropriate recombinant inbred mouse strains, the Hip1 locus was further localised to a 2 Mb interval, which contained only nine genes. Expression analysis showed that the only gene differentially expressed in islets isolated from the parental strains was Nnt, which encodes the mitochondrial proton pump, nicotinamide nucleotide transhydrogenase (NNT). We also found in five mouse strains a positive correlation (r 2 = 0.90, p < 0.01) between NNT activity and first-phase insulin secretion, emphasising the importance of this enzyme in beta cell function. Furthermore, of these five strains, only those with high NNT activity are known to exhibit severe diabetes after becoming obese.
Conclusions/interpretation Insulin hypersecretion is associated with increased Nnt expression. We suggest that NNT must play an important role in beta cell function and that its effect on the high insulin secretory capacity of the DBA/2 mouse may predispose beta cells of these mice to failure.
Methods Intravenous glucose tolerance tests followed by a genome-wide scan were performed on 171 (C57BL/6 × DBA/2) × C57BL/6 backcross mice.
Results A quantitative trait locus, designated hyperinsulin production-1 (Hip1), was mapped with a logarithm of odds score of 7.7 to a region on chromosome 13. Production of congenic mice confirmed that Hip1 influenced the insulin hypersecretion trait. By studying appropriate recombinant inbred mouse strains, the Hip1 locus was further localised to a 2 Mb interval, which contained only nine genes. Expression analysis showed that the only gene differentially expressed in islets isolated from the parental strains was Nnt, which encodes the mitochondrial proton pump, nicotinamide nucleotide transhydrogenase (NNT). We also found in five mouse strains a positive correlation (r 2 = 0.90, p < 0.01) between NNT activity and first-phase insulin secretion, emphasising the importance of this enzyme in beta cell function. Furthermore, of these five strains, only those with high NNT activity are known to exhibit severe diabetes after becoming obese.
Conclusions/interpretation Insulin hypersecretion is associated with increased Nnt expression. We suggest that NNT must play an important role in beta cell function and that its effect on the high insulin secretory capacity of the DBA/2 mouse may predispose beta cells of these mice to failure.
History
Journal
DiabetologiaVolume
50Issue
12Pagination
2476 - 2485Publisher
SpringerLocation
Heidelberg, GermanyPublisher DOI
Link to full text
ISSN
0012-186XeISSN
1432-0428Language
engPublication classification
C1.1 Refereed article in a scholarly journalCopyright notice
2007, Springer-VerlagUsage metrics
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genetic predispositioninsulin secretionintravenous glucose tolerance testIslet beta cell functionquantitative trait locusScience & TechnologyLife Sciences & BiomedicineEndocrinology & MetabolismGLUCOSE-HOMEOSTASISSECRETORY FUNCTIONINDUCED IMPAIRMENTRECEPTOR-1 GENERESISTANCEC57BL\/6JMICELOCUSIDENTIFICATIONPOLYMORPHISM
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