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S Omori,
Y Tanaka,
M Horikoshi,
A Takahashi, K Hara,
H Hirose,
A Kashiwagi,
K Kaku,
R Kawamori,
T Kadowaki,
Y Nakamura,
S Maeda
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ABSTRACT: Additional susceptibility loci for type 2 diabetes have been identified by a meta-analysis of genome-wide association studies (GWASs) in European populations. To examine further the roles of these new loci, we performed a replication study for the association of these single-nucleotide polymorphism (SNP) loci with the disease in three independent Japanese populations.
We genotyped seven of the 11 SNPs that emerged in stage 2 of the meta-analysis for European GWASs (rs864745 in JAZF1, rs12779790 near CDC123/CAMK1D, rs7961581 near TSPAN8/LGR5, rs4607103 near ADAMTS9, rs10923931 in NOTCH2, rs1153188 near DCD and rs9472138 near VEGFA) for three independent Japanese populations (first set, 1,630 type 2 diabetes patients vs 1,064 controls; second set, 1,272 type 2 diabetes patients vs 856 controls; third set, 486 type 2 diabetes patients vs 936 controls) using a TaqMan assay. The association of the SNP loci in each population was analysed using a logistic regression analysis, adjusting for age, sex and BMI, and the data were evaluated by a meta-analysis.
A meta-analysis for the three case-control studies identified a nominal association of rs864745 in JAZF1 with type 2 diabetes (OR 1.148, 95% CI 1.034-1.275, p = 0.0098, corrected p = 0.069). The association of other loci did not reach statistically significant levels (nominal p > 0.05).
From these results the contribution of these seven loci in conferring susceptibility to type 2 diabetes is considered minor in the Japanese population, if they are present.
Diabetologia 06/2009; 52(8):1554-60. · 6.81 Impact Factor
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ABSTRACT: Recently, several groups have carried out whole-genome association studies in European and European-origin populations and found novel type 2 diabetes-susceptibility genes, fat mass and obesity associated (FTO), solute carrier family 30 (zinc transporter), member 8 (SLC30A8), haematopoietically expressed homeobox (HHEX), exostoses (multiple) 2 (EXT2), CDK5 regulatory subunit associated protein 1-like 1 (CDKAL1), cyclin-dependent kinase inhibitor 2B (p15, inhibits CDK4) (CDKN2B) and insulin-like growth factor 2 mRNA binding protein 2 (IGF2BP2), which had not been in the list of functional candidates. The aim of this study was to determine the association between single nucleotide polymorphisms (SNPs) in these genes and type 2 diabetes in participants from the Japanese population.
Sixteen previously reported SNPs were genotyped in 864 Japanese type 2 diabetes individuals (535 men and 329 women; age 63.1 +/- 9.5 years (mean+/-SD), BMI 24.3 +/- 3.9 kg/m(2)) and 864 Japanese control individuals (386 men and 478 women; age 69.5 +/- 6.8 years, BMI 23.8 +/- 3.7 kg/m(2)).
The SNPs rs5015480 [odds ratio (OR) = 1.46 (95% CI 1.20-1.77), p = 2.0 x 10(-4)], rs7923837 [OR = 1.40 (95% CI 1.17-1.68), p = 2.0 x 10(-4)] and rs1111875 [OR = 1.30 (95% CI 1.11-1.52), p = 0.0013] in HHEX were significantly associated with type 2 diabetes with the same direction as previously reported. SNP rs8050136 in FTO was nominally associated with type 2 diabetes [OR = 1.22 (95% CI 1.03-1.46), p = 0.025]. SNPs in other genes such as rs7756992 in CDKAL1, rs10811661 in CDKN2B and rs13266634 in SLC30A8 showed nominal association with type 2 diabetes. rs7756992 in CDKAL1 and rs10811661 in CDKN2B were correlated with impaired pancreatic beta cell function as estimated by the homeostasis model assessment beta index (p = 0.023, p = 0.0083, respectively).
HHEX is a common type 2 diabetes-susceptibility gene across different ethnic groups.
Diabetologia 01/2008; 50(12):2461-6. · 6.81 Impact Factor
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ABSTRACT: It has been suggested that transcription factor 7-like 2 protein (TCF7L2) plays an important role in glucose metabolism by regulating the production level of glucagon-like peptide-1, a hormone which modifies glucose-dependent insulin secretion. Recently, variants of TCF7L2 gene were reported to confer an increased risk of type 2 diabetes in three different samples from European and European-origin populations. We studied whether the single nucleotide polymorphisms (SNPs) in TCF7L2 were associated with type 2 diabetes in samples from a Japanese population.
Five SNPs were genotyped in three different sample sets. Association with type 2 diabetes was investigated in each, as well as in combined sample sets.
The SNP rs7903146 was nominally associated with type 2 diabetes in the initial (p = 0.08) and two replication sample sets (p = 0.05 and 0.06). For the combined sample set, in which we successfully genotyped 1,174 type 2 diabetes patients and 823 control subjects, rs7903146 showed a significant association with type 2 diabetes (odds ratio = 1.69 [95% CI 1.21-2.36], p = 0.002) with the same direction as the previous reports in samples from European and European-origin populations. SNPs rs7903146 and rs7901695 were in complete linkage disequilibrium. The rest of the five SNPs (rs7895340, rs11196205 and rs12255372) did not show any significant associations with type 2 diabetes.
The consistent association between rs7903146 in TCF7L2 and type 2 diabetes in different ethnic groups, including the Japanese population, suggests that TCF7L2 is a common susceptibility gene for type 2 diabetes.
Diabetologia 05/2007; 50(4):747-51. · 6.81 Impact Factor
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K Hara,
M Horikoshi,
H Kitazato,
T Yamauchi,
C Ito,
M Noda,
J Ohashi,
P Froguel,
K Tokunaga,
R Nagai,
T Kadowaki
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ABSTRACT: Secreted by adipocytes, adiponectin is a hormone that acts as an antidiabetic and anti-atherogenic adipokine. We recently cloned the genes encoding two adiponectin receptors (ADIPOR1 and ADIPOR2). The aim of this study was to examine whether ADIPOR1 and/or ADIPOR2 play a major role in genetic susceptibility to insulin resistance or type 2 diabetes in the Japanese population.
By direct sequencing and a search of public databases, we identified single nucleotide polymorphisms (SNPs) in ADIPOR1 and ADIPOR2, and investigated whether these SNPs are associated with insulin resistance and type 2 diabetes in the Japanese population.
The linkage disequilibrium (LD) in the chromosomal region of ADIPOR1 was almost completely preserved, whereas the LD in ADIPOR2 was less well preserved. None of the SNPs in ADIPOR1 or ADIPOR2 were significantly associated with insulin resistance or type 2 diabetes. No differences in ADIPOR1 or ADIPOR2 haplotype frequencies were observed between type 2 diabetic and non-diabetic subjects.
Genetic variations in ADIPOR1 or ADIPOR2 are unlikely to lead to a common genetic predisposition to insulin resistance or type 2 diabetes in the Japanese population.
Diabetologia 08/2005; 48(7):1307-14. · 6.81 Impact Factor
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ABSTRACT: Peroxisome proliferator activated receptor gamma coactivator-1 (PGC-1), a transcriptional coactivator of the nuclear receptor PPARgamma, plays a role in adaptive thermogenesis and insulin sensitivity. Plasma fasting insulin has been linked to the chromosomal region where the PGC-1 gene is located. Thus, PGC-1 can be viewed as a functional and positional candidate for the susceptibility gene for Type II (non-insulin-dependent) diabetes mellitus.
After screening the PGC-1 gene for single nucleotide polymorphisms (SNPs), we performed an association study using the newly detected SNPs in 537 Type II diabetic patients and 417 non-diabetic subjects.
We found three relatively frequent SNPs in the PGC-1 gene (IVS4-11T > C, Thr394Thr and Gly482Ser). There were significant differences in fasting insulin (Gly/Gly; 37.7 +/- 1.43, Gly/Ser; 40.2 +/- 1.21, Ser/Ser; 44.3 +/- 1.82 pmol/l, p = 0.018) and insulin resistance index (Gly/Gly; 1.48 +/- 0.06, Gly/Ser; 1.56 +/- 0.05, Ser/Ser; 1.75 +/- 0.08, p = 0.027) according to the genotype of the Gly482Ser polymorphism. The Thr394Thr - Gly482Ser haplotype was associated with Type II diabetes (p = 0.00003). CONCLUSION/INTERPRETATION. The results of this study suggested that the PGC-1 gene might be implicated in the pathogenesis of Type II diabetes.
Diabetologia 05/2002; 45(5):740-3. · 6.81 Impact Factor
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T Yamauchi,
J Kamon,
H Waki,
Y Terauchi,
N Kubota, K Hara,
Y Mori,
T Ide,
K Murakami,
N Tsuboyama-Kasaoka, [......],
H Kagechika,
K Shudo,
M Yoda,
Y Nakano,
K Tobe,
R Nagai,
S Kimura,
M Tomita,
P Froguel,
T Kadowaki
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ABSTRACT: Adiponectin is an adipocyte-derived hormone. Recent genome-wide scans have mapped a susceptibility locus for type 2 diabetes and metabolic syndrome to chromosome 3q27, where the gene encoding adiponectin is located. Here we show that decreased expression of adiponectin correlates with insulin resistance in mouse models of altered insulin sensitivity. Adiponectin decreases insulin resistance by decreasing triglyceride content in muscle and liver in obese mice. This effect results from increased expression of molecules involved in both fatty-acid combustion and energy dissipation in muscle. Moreover, insulin resistance in lipoatrophic mice was completely reversed by the combination of physiological doses of adiponectin and leptin, but only partially by either adiponectin or leptin alone. We conclude that decreased adiponectin is implicated in the development of insulin resistance in mouse models of both obesity and lipoatrophy. These data also indicate that the replenishment of adiponectin might provide a novel treatment modality for insulin resistance and type 2 diabetes.
Nature Medicine 09/2001; 7(8):941-6. · 22.46 Impact Factor
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Nippon rinsho. Japanese journal of clinical medicine 03/2001; 59 Suppl 2:489-97.
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ABSTRACT: Neurogenin 3 (ngn3) is a transcription factor expressed in the endocrine precursor cells of the pancreas. It has recently been reported that ngn3-deficient mice show absence of pancreatic endocrine cells and die of postnatal diabetes. The purpose of this investigation was to screen for polymorphisms of the ngn3 gene and to test whether these polymorphisms are associated with Type II (non-insulin-dependent) diabetes mellitus in the Japanese subjects.
We screened ngn3 gene and upstream region by direct sequencing and estimated the prevalence of polymorphisms in 197 patients with Type II (non-insulin-dependent) diabetes mellitus and 216 control subjects.
We identified four novel polymorphisms, Ser199Phe (596C/T), -43insCA, -983C/T and -1822G/A. In an association study the allelic frequencies of the major allele of these four polymorphisms were 0.721, 0.914, 0.912 and 0.530 in diabetic patients, respectively, and 0.694, 0.905, 0.917 and 0.537 in control subjects, respectively.
Mutations and polymorphisms of ngn3 gene are not significantly associated with Type II (non-insulin-dependent) diabetes mellitus in the Japanese subjects.
Diabetologia 03/2001; 44(2):241-4. · 6.81 Impact Factor
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K Hara,
N Kubota,
K Tobe,
Y Terauchi,
H Miki,
K Komeda,
H Tamemoto,
T Yamauchi,
R Hagura,
C Ito,
Y Akanuma,
T Kadowaki
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ABSTRACT: The biological role of peroxisome proliferator-activated receptor gamma (PPARgamma) was investigated by gene targeting and case-control study of the Pro12Ala PPARgamma2 polymorphism. Homozygous PPARgamma-deficient embryos died at 10.5-11.5 days post conception (dpc) due to placental dysfunction. Heterozygous PPARgamma-deficient mice were protected from the development of insulin resistance due to adipocyte hypertrophy under a high-fat diet, whose phenotypes were abrogated by PPARgamma agonist treatment. Heterozygous PPARgamma-deficient mice showed overexpression and hypersecretion of leptin despite the smaller size of adipocytes and decreased fat mass, which may explain these phenotypes at least in part. This study reveals a hitherto unpredicted role for PPARgamma in high-fat diet-induced obesity due to adipocyte hypertrophy and insulin resistance, which requires both alleles of PPARgamma. A Pro12Ala polymorphism has been detected in the human PPARgamma2 gene. Since this amino acid substitution may cause a reduction in the transcriptional activity of PPARgamma, this polymorphism may be associated with decreased insulin resistance and decreased risk of type 2 diabetes. To investigate this hypothesis, we performed a case-control study of the Pro12Ala PPARgamma2 polymorphism. In an obese group, subjects with Ala12 were more insulin sensitive than those without. The frequency of Ala12 was significantly lower in the diabetic group, suggesting that this polymorphism protects against type 2 diabetes. These results revealed that in both mice and humans, PPARgamma is a thrifty gene mediating type 2 diabetes.
British Journal Of Nutrition 01/2001; 84 Suppl 2:S235-9. · 3.01 Impact Factor
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K Hara,
T Okada,
K Tobe,
K Yasuda,
Y Mori,
H Kadowaki,
R Hagura,
Y Akanuma,
S Kimura,
C Ito,
T Kadowaki
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ABSTRACT: Peroxisome proliferator-activated receptor gamma (PPARgamma) has been implicated in adipocyte differentiation. Recently it was reported that heterozygous deficiency of PPARgamma led to the protection from high-fat diet-induced insulin resistance in an animal model. A Pro12Ala polymorphism has been detected in the human PPARgamma2 gene. Since this amino acid substitution may cause a reduction in the transcriptional activity of PPARgamma, this polymorphism may be associated with decreased insulin resistance and decreased risk of type 2 diabetes. To investigate this hypothesis, we performed a case-control study of the Pro12Ala PPARgamma2 polymorphism in Japanese diabetic and non-diabetic subjects. The frequency of Ala12 was significantly lower in the diabetic group. In an overweight or obese group, subjects with Ala12 were more insulin sensitive than those without. These results suggest that the PPARgamma is a thrifty gene and that the Pro12Ala PPARgamma2 polymorphism protects against type 2 diabetes in the Japanese.
Biochemical and Biophysical Research Communications 05/2000; 271(1):212-6. · 2.48 Impact Factor
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ABSTRACT: A 45-year-old Japanese man was referred to our hospital because of hyperglycemia despite the administration of as much as 120 U/day of human insulin. He had no history of injecting animal insulin. Free insulin was below 5 microU/ml, but a high titer of total insulin (about 3,000 microU/ml) was observed, suggesting the presence of antibodies against human insulin. Scatchard analysis showed an increased insulin binding capacity in the plasma characterized by a higher affinity for insulin. He was successfully treated by cessation of insulin administration. A Scatchard analysis series showed that a reduction in the insulin binding capacity of antibodies paralleled the improvement in glycemic control.
Internal Medicine 03/2000; 39(2):143-5. · 0.94 Impact Factor
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ABSTRACT: An insulin-stimulated phosphorylation cascade was examined in rat liver after insulin injection via a portal vein by the use of immune complex kinase assays specific to the mitogen-activated protein (MAP) kinase and S6 kinase II homologue (rsk) kinase. We have prepared an antibody against the peptide consisting of a carboxyl-terminal portion of the extracellular signal-regulated kinase 1 (alpha C92), one of the MAP kinases, and an antibody against the peptide consisting of the carboxyl terminus of the mouse S6 kinase II homologue (alpha rsk(m)C). In alpha C92 immune complex assay, maximal activation of rat liver MAP kinases (approximately 4.3-fold) were observed 4.5 min after insulin injection. We also observed an insulin-stimulated MAP kinase activity (approximately 3-fold) in liver extracts from insulin-treated rat in fractions eluted from phenyl-Sepharose with 30-50% ethylene glycol. Kinase assay in myelin basic protein (MBP)-containing gel after sodium dodecyl sulfate-polyacrylamide gel electrophoresis followed by denaturation with 6 M guanidine HCl, and renaturation revealed that insulin injection stimulated the kinase activity of the 42- and 44-kDa proteins, which corresponded to the two distinct MAP kinases. In alpha rsk(m)C immune complex assay, maximal stimulation (approximately 5-fold) of the S6 peptide (Arg-Arg-Leu-Ser-Ser-Leu-Arg-Ala) kinase activity was observed 7.5 min after insulin injection. In addition, MAP kinases purified from insulin-treated rat liver were able to activate S6 peptide kinase activity in vitro in alpha rsk(m)C immunoprecipitates from untreated rat liver, accompanied by the appearance of several phosphorylated bands including a major band at 88 kDa. We also examined whether insulin injection stimulates the MAP kinase activator (Ahn, N. G., Seger, R., Bratlien, R. L., Diltz, C. D., Tonks, N. K., and Krebs, E. G. (1991) J. Biol. Chem. 266, 4220-4227) in rat liver. Using recombinant Xenopus MAP kinase, fractions of Q-Sepharose eluted early in the NaCl gradient were found to have MAP kinase activator activity accompanied by the phosphorylation of 42-kDa recombinant Xenopus MAP kinase. From these data, we demonstrate three tiers of a cascade composed of the MAP kinase activator, MAP kinases, and an S6 peptide kinase activity in rat liver under physiological conditions in the intact animal.
Journal of Biological Chemistry 11/1992; 267(29):21089-97. · 4.77 Impact Factor
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ABSTRACT: Two site-specific antibodies have been prepared by immunizing rabbits with chemically synthesized peptides derived from the partial cDNA-predicted amino acid sequence of extracellular signal-regulated kinase 1 (ERK1), which has been proposed to encode the microtubule-associated protein 2 (MAP2) kinase (Boulton, T. G., Yancopoulos, G. D., Gregory, J. S., Slauer, C., Moomaw, C., Hsu, J., and Cobb, M. H. (1990) Science 249, 64-67). With immunoprecipitation in the presence of sodium dodecyl sulfate (SDS) and Western blotting, an antibody to the peptide containing triple tyrosine residues (alpha Y91) resembling one of the insulin receptor autophosphorylation sites specifically recognized 42- and 44-kDa proteins. On the other hand, an antibody to the peptide corresponding to the COOH terminus portions (alpha C92) of the ERK1 cDNA gene product recognized the 44-kDa protein much more efficiently than the 42-kDa protein. With immunoprecipitation in the absence of SDS, alpha Y91 could barely recognize these two proteins and alpha C92 recognized the 44-kDa protein but failed to recognize the 42-kDa protein. Kinase assays in myelin basic protein (MBP)-containing gel, after SDS-polyacrylamide gel electrophoresis, revealed that insulin or 12-O-tetradecanoylphorbol-13-acetate (TPA)-stimulated MBP kinase activity in alpha Y91 immunoprecipitates comigrated at molecular mass 42 and 44 kDa. On the other hand, the stimulated MBP kinase activity in alpha C92 immunoprecipitates comigrated only at molecular mass 44 kDa. Insulin stimulated the MBP kinase activity in gels and phosphorylation of these two proteins by greater than 10-fold with a maximal level at 5 min. Insulin and TPA rapidly stimulate the phosphorylation of the 42- and 44-kDa proteins via de novo threonine and tyrosine phosphorylation. Tryptic phosphopeptide mapping analysis of the 42- and 44-kDa proteins, respectively, revealed a single major phosphopeptide containing phosphothreonine and phosphotyrosine, which was common to both insulin- and TPA-stimulated phosphoproteins. Protein phosphatase 2A treatment of these two phosphoproteins caused a complete loss of kinase activity with selective dephosphorylation of phosphothreonine. These data strongly suggest that these two proteins are highly related to the mitogen-activated protein (MAP) kinase with an apparent molecular mass of 42 kDa (Ray, L. B., and Sturgill, T. W. (1988) Proc. Natl. Acad. Sci. U.S.A. 85, 3753-3757) and that these two immunologically similar but distinct MBP/MAP2 kinases may represent isozymic forms of MBP/MAP2 kinases. These data also demonstrate that insulin and TPA activate MBP/MAP2 kinase activity by de novo phosphorylation of threonine and tyrosine residues via a very similar pathway.
Journal of Biological Chemistry 01/1992; 266(36):24793-803. · 4.77 Impact Factor
