The human forkhead box O1A (FOXO1A) gene on chromosome 13q14.1 is a key transcription factor in insulin signaling in liver and adipose tissue and plays a central role in the regulation of key pancreatic β-cell genes including IPF1. We hypothesized that sequence variants of FOXO1A contribute to the observed defects in hepatic and peripheral insulin action and altered β-cell compensation that characterize type 2 diabetes (T2DM). To test this hypothesis, we screened the three exons, 3′ untranslated region, and 5′ flanking region for sequence variants in Caucasian and African-American individuals with early onset (<45 years) T2DM. We identified only six variants; none altered the coding sequence, and except for one variant in the 3′ untranslated region, they were rare or absent in Caucasians. To increase coverage of the gene, we selected seven additional variants in the large first intron and 5′ flanking region, thus providing 13 variants that spanned 116.4 kb. Based on frequency and linkage disequilibrium patterns in a subset of individuals, we selected eight SNPs to type in a Caucasian population comprising 192 unrelated nondiabetic control individuals and 192 individuals with T2DM, and 10 SNPs to type in 182 controls and 352 diabetic individuals of African-American ancestry. No variant was associated with T2DM (African-Americans, p > 0.08; Caucasians, p > 0.09). Of the 8 Caucasian SNPs, six comprised a single haplotype block spanning over 100 kb and including most of the large first intron. In contrast, no block was observed among SNPs typed in African-Americans. No haplotype was associated with T2DM. FOXO1A variation is rare and is unlikely to contribute to T2DM in either Caucasian or African-American populations.

京都大学 / 0048 / 新制・課程博士 / 博士(医学) / 甲第20616号 / 医博第4265号 / 新制||医||1023(附属図書館) / 京都大学大学院医学研究科医学専攻 / (主査)教授 長船 健二, 教授 渡邊 直樹, 教授 岩田 想 / 学位規則第4条第1項該当 / Doctor of Medical Science / Kyoto University / DFAM

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O hiperinsulinismo congênito (CHI) é um distúrbio do pâncreas endócrino, mais freqüentemente causado por alterações dos canais de membrana KATP das células , resultando em secreção inapropriada de insulina e hipoglicemia severa e persistente nos recém-nascidos, que leva ao óbito ou a seqüelas neurológicas graves, se não diagnosticado a tempo. O diagnóstico depende da análise dos dados clínicos, laboratoriais, morfológicos e genético-moleculares (50% apresentam mutações dos canais KATP). As duas formas histopatológicas descritas requerem cirurgias radicalmente opostas: pancreatectomia quase-total (95-98%) na forma difusa que acomete todo o pâncreas, ou apenas exerese do foco adenomatoso de células , medindo em média 4,5 mm, na forma focal, e portanto a sua distinção é essencial durante o exame intra-operatório de congelação ou através de [18F]-L-Dopa PET-CT. Dez pacientes com CHI difuso e um com CHI focal, submetidos a pancreatectomia, foram analisados em relação a parâmetros clínicos, histopatológicos, de proliferação das células (IHQ de dupla marcação Ki-67 / insulina) e quanto à presença de mutações nos genes das únicas duas proteínas (SUR 1 e Kir 6.2) que formam os canais KATP, e comparados a 19 pâncreas controles normais da mesma faixa etária. Pacientes e controles foram estratificados em 3 meses e > 3 meses de idade. Nucleomegalia, ausente nos controles, foi observada apenas na forma difusa. Os critérios histológicos de maturação normalmente mais freqüentes nos controles 3 meses, foram freqüentemente observados nos recém-nascidos com CHI difuso > 3 meses, sugerindo um retardo na maturação do pâncreas endócrino destes pacientes. O índice de proliferação das células (Ki-67- LI), muito elevado nos focos adenomatosos da forma focal, foi útil na distinção destes focos dos agregados frouxos de ilhotas, histologicamente muito semelhantes, observados em dois casos difusos e um controle, que apresentam níveis de Ki-67-LI cerca de 10 vezes menor. Na forma difusa o Ki-67-LI também foi estatisticamente mais alto do que nos controles. Este é o primeiro estudo de pacientes com CHI no Brasil, e embora existam diferenças epidemiológicas entre os países relacionadas à determinação genética do CHI, não foram constatadas mutações ou novos polimorfismos nos exons 33-37 do gene ABCC8 (SUR 1) de 10/10 pacientes ou no único exon do gene KCNJ11 (Kir 6.2) de 4/10 pacientes / Congenital hyperinsulinism (CHI) is a rare pancreatic endocrine cell disease which most severe cases are found to be, at least in half of patients, associated with genetic defects in the -cell KATP channels. The aim of this study was to evaluate eleven Brazilian patients diagnosed, by standard criteria, as CHI non responsive to clinical therapy, and submitted to pancreatectomy, regarding: histology, -cell proliferation (IHC Ki-67 / insulin) and -cell KATP channels genes mutations in blood samples. For comparison of histology and -cell proliferation, 19 pancreatic control samples were included. According histology, ten patients were classified as diffuse and one as focal form. Nucleomegaly and -cells with abundant cytoplasm were absent in controls, and observed only in the group of diffuse CHI patients. Ki- 67-LI was useful to differentiate the adenomatous areas of the focal form CHI neonate from loose clusters of islets found in two diffuse form and one control samples. Proliferation was much higher in the focal CHI adenomatous areas, but diffuse CHI patients also have statistically higher Ki-67-LI than controls. This is the first genetic study of CHI patients in Brazil, and no mutations or new polymorphisms were found in the ABCC8 gene (SUR 1) (exons 33-37) or in the only exon of KCNJ11 gene (Kir 6.2) in 4/4 patients evaluated. On the other hand, enhanced -cell proliferation seems to be a constant feature in these patients both in diffuse and focal forms

Submitted by Rosivalda Pereira (mrs.pereira@ufma.br) on 2017-06-14T17:35:19Z No. of bitstreams: 1 DanyloMelo.pdf: 745489 bytes, checksum: c5ad51adb0decdb7d8050bcf5074660b (MD5) / Made available in DSpace on 2017-06-14T17:35:19Z (GMT). No. of bitstreams: 1 DanyloMelo.pdf: 745489 bytes, checksum: c5ad51adb0decdb7d8050bcf5074660b (MD5) Previous issue date: 2016-09-29 / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES) / Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPQ) / Fundação de Amparo à Pesquisa e ao Desenvolvimento Científico e Tecnológico do Maranhão (FAPEMA) / Synthetic glucocorticoids (GCs) induce several adverse effects when administered in high doses and/or prolonged, as peripheral insulin resistance, glucose intolerance, and alterations in lipid metabolism, especially hypertriglyceridemia. There are few studies on the metabolic impact caused by long-term treatments with different synthetic GCs, especially with prednisone, GC of intermediate action and first choice in its pharmacologic class. Therefore, we seek to verify the metabolic alterations caused by sub chronic treatment with prednisone in rats and compare them with existing and in acute model of insulin resistance induced by dexamethasone effects. For this, Wistar rats with of 90 days were treated with dexamethasone (D5) (1 mg/kg, i.p.) for 5 consecutive days and, its controls (C5) with saline, and Wistar rats of 60 days old were treated with prednisone (80 mg/kg, orally) for 15 days (P15) and 30 days (P30) consecutive and their respective controls (C15 and C30), received vehicle solution. The D5 results a decreased body weight (12.3%) and lower weight of retroperitoneal fat (38%), increased serum fasting glucose (12%) and fed (30%), insulin (80%) and triglycerides (339%) (p <0.05). Total fat and triglycerides liver were 29% and 52% higher in rats D5, compared to the C5 rats (p <0.05). The P15 rats had increased weight 61% less, reduction of retroperitoneal fat (29%) and increased plasma triglyceride concentrations (60%) compared to the C15 rats (p <0.05). As long as P30 rats had increased weight 44% less, reduction of retroperitoneal fat (25%) and increased serum triglycerides (78%) and liver total fat (26%) compared to the C30 rats (p <0,05). In vivo tests revealed the presence of impaired glucose tolerance (oGTT) in rats D5 and P30, and reduced insulin sensitivity (ipITT, HOMA, TYG) in D5 animals (p <0.05). Ex vivo test showed greater sensitivity in the pancreatic islets front glucose only in D5 rats. In conclusion, the sub chronic administration of prednisone promoted finer metabolic changes in glucose homeostasis, compared to acute administration of dexamethasone, suggesting the preferential use of prednisone when it is intended to minimize the adverse metabolic effects associated with the use of GCs. / Os glicocorticoides (GCs) sintéticos podem induzir diversos efeitos adversos, quando administrados em doses elevadas e/ou por tempo prolongado, como resistência insulínica periférica, intolerância à glicose, e alterações no metabolismo lipídico, especialmente hipertrigliceridemia. Porém existem poucos estudos sobre o impacto metabólico promovido por tratamentos prolongados com diferentes GCs sintéticos, especialmente com a prednisona, GC de ação intermediária e de primeira escolha em sua classe farmacológica. Diante disso, buscou-se verificar as alterações metabólicas ocasionadas pelo tratamento subcrônico com prednisona em ratos e compará-las aos efeitos presentes e conhecidos em modelo agudo de indução de resistência insulínica pela dexametasona. Para tal, ratos Wistar com noventa dias de vida foram tratados com dexametasona (D5) (1 mg/Kg, i.p.) durante 5 dias consecutivos e, os seus controles (C5) com salina, e ratos Wistar com 60 dias de vida foram tratados com prednisona (80 mg/Kg, v.o.) durante 15 dias (P15) e 30 dias (P30) consecutivos e, os seus respectivos controles (C15 e C30), receberam veículo. Os ratos D5 apresentaram redução do peso corpóreo (12,3%) e menor peso da gordura retroperitoneal (38%), aumento das concentrações séricas de glicose em jejum (12%) e alimentado (30%), insulina (80%) e triglicerídeos (339%) (p<0,05). O conteúdo de gordura total hepático, bem como triglicerídeos foram 29% e 52% maiores nos ratos D5, em relação aos ratos C5 (p<0,05). Os ratos P15 apresentaram um ganho de peso 61% menor, redução da gordura retroperitoneal (29%) e aumento nas concentrações plasmáticas de triglicerídeos (60%), em relação aos ratos C15 (p<0,05). Enquanto os ratos P30 apresentaram um ganho de peso 44% menor, redução da gordura retroperitoneal (25%) e aumento nas concentrações séricas de triglicerídeos (78%) e gordura total hepática (26%), em relação aos ratos C30 (p<0,05). Os testes in vivo revelaram a presença de intolerância à glicose (GTT) nos ratos D5 e P30 e redução da sensibilidade à insulina (ITT, HOMA, TyG) nos animais D5 (p<0,05). O teste ex vivo revelou maior sensibilidade nas ilhotas pancreáticas frente à glicose somente nos ratos D5. Em conclusão, a administração subcrônica de prednisona promoveu alterações metabólicas mais sutis na homeostasia da glicose, quando comparada à administração aguda de dexametasona, sugerindo assim, o uso preferencial da prednisona quando se pretende minimização dos efeitos adversos metabólicos associados ao uso de GCs.

Ho Sin Ka Janice. / Thesis (M.Phil.)--Chinese University of Hong Kong, 2008. / Includes bibliographical references (leaves 105-119). / Abstracts in English and Chinese. / Chapter CHAPTER 1. --- Introduction / Chapter 1.1. --- Epidemiology of Type 2 Diabetes --- p.1 / Chapter 1.2. --- Risk factors contributing to Type 2 Diabetes --- p.3 / Chapter 1.2.1. --- Environmental and physiological factors --- p.3 / Chapter 1.2.2. --- Genetic factors --- p.3 / Chapter 1.3. --- Disruption of energy homeostasis in the pathogenesis of type 2 diabetes --- p.6 / Chapter 1.3.1. --- Clinical spectrum of diabetes --- p.6 / Chapter 1.3.2. --- Insulin as a key regulator of energy homeostasis --- p.7 / Chapter 1.3.3. --- Insulin secretion and glucose metabolism --- p.8 / Chapter 1.3.4. --- Insulin action and lipid metabolism --- p.9 / Chapter 1.3.5. --- Lipotoxicity and glucotoxicity --- p.12 / Chapter 1.3.6. --- Role of transcription factors as metabolic switch --- p.13 / Chapter 1.4. --- Candidate genes implicated in type 2 diabetes susceptibility --- p.15 / Chapter 1.4.1. --- Candidate genes involved in insulin secretion pathway --- p.15 / Chapter 1.4.1.1. --- HNF4A --- p.15 / Chapter 1.4.1.2. --- HNF1A --- p.16 / Chapter 1.4.1.3. --- PDX1/PBX1 --- p.17 / Chapter 1.4.1.4. --- NEUROD1 --- p.17 / Chapter 1.4.1.5. --- GCK --- p.17 / Chapter 1.4.1.6. --- KCNJ11/ABCC8 --- p.18 / Chapter 1.4.2 --- Candidate genes involved in insulin action pathway --- p.19 / Chapter 1.4.2.1. --- PPARG --- p.19 / Chapter 1.4.2.2. --- PPARA --- p.20 / Chapter 1.4.2.3. --- PPARGC1A --- p.20 / Chapter 1.4.2.4. --- ADIP0Q --- p.21 / Chapter 1.4.2.5. --- LPL --- p.21 / Chapter 1.4.2.6. --- UPC --- p.22 / Chapter 1.5. --- Hypothesis and objectives of the study --- p.23 / Chapter CHAPTER 2. --- Materials and methods / Chapter 2.1. --- Study design --- p.25 / Chapter 2.1.1. --- Two-stage candidate gene association design --- p.25 / Chapter 2.1.2. --- Power calculation --- p.27 / Chapter 2.2. --- Study cohort --- p.29 / Chapter 2.2.1. --- Subject recruitment --- p.29 / Chapter 2.2.2. --- Clinical and biochemical measurements --- p.30 / Chapter 2.2.3. --- Clinical definitions --- p.31 / Chapter 2.3. --- Genetic study --- p.32 / Chapter 2.3.1. --- Candidate gene selection --- p.32 / Chapter 2.3.2. --- SNP selection --- p.32 / Chapter 2.3.3. --- DNA sample preparation --- p.35 / Chapter 2.3.4. --- Genotyping methods --- p.36 / Chapter 2.3.4.1. --- Allele specific Tm shift assay --- p.36 / Chapter 2.3.4.2. --- Mass spectrometry assay --- p.40 / Chapter 2.4. --- Data quality control --- p.42 / Chapter 2.4.1. --- Stage 1 --- p.42 / Chapter 2.4.2. --- Stage 2 --- p.42 / Chapter 2.5. --- Statistical analysis --- p.45 / Chapter 2.5.1. --- Stage 1 analysis --- p.45 / Chapter 2.5.2. --- Stage 2 analysis --- p.45 / Chapter 2.5.3. --- Stage 1 and 2 combined analysis --- p.46 / Chapter CHAPTER 3. --- Results / Chapter 3.1. --- Clinical characteristics of subjects in stages 1 and 2 studies --- p.48 / Chapter 3.2. --- Case-control associations in stage 1 --- p.51 / Chapter 3.2.1. --- Association with T2D --- p.51 / Chapter 3.2.2. --- Association with T2D subset by metabolic syndrome --- p.54 / Chapter 3.3. --- Case-control associations in stage 2 --- p.60 / Chapter 3.3.1. --- SNP selection for genotyping --- p.60 / Chapter 3.3.2. --- Association with T2D --- p.63 / Chapter 3.3.3. --- Association with T2D subset by metabolic syndrome --- p.64 / Chapter 3.4. --- Case-control associations in combined stages 1 and 2 --- p.66 / Chapter 3.4.1. --- Association with T2D --- p.66 / Chapter 3.4.2. --- Association with T2D subset by metabolic syndrome --- p.70 / Chapter 3.4.3. --- Association with T2D subset by age at diagnosis --- p.74 / Chapter 3.4.4. --- Association with T2D subset by gender --- p.76 / Chapter 3.4.5. --- Genetic epistasis for T2D association --- p.79 / Chapter 3.5. --- Metabolic traits associations in control subjects in combined stages 1 and 2 studies --- p.83 / Chapter CHAPTER 4. --- Discussion --- p.86 / Chapter 4.1. --- Role of insulin secretion genes in type 2 diabetes --- p.87 / Chapter 4.2. --- Role of insulin action genes in type 2 diabetes --- p.92 / Chapter 4.3. --- Combined genetic effects on risk for type 2 diabetes --- p.97 / Chapter 4.4. --- Summary --- p.98 / Chapter 4.5. --- Limitation of this study and future direction --- p.101 / REFERENCES --- p.104 / APPENDICES --- p.119 / Chapter Appendix 1: --- Gene structure and linkage disequilibrium of genotyped SNPs of candidate genes --- p.119 / Chapter Appendix 2: --- Information of SNPs genotyped in stage 1 --- p.130 / Chapter Appendix 3: --- T2D association results (additive model) of 152 SNPs for stage 1 case- control samples --- p.137 / Chapter Appendix 4: --- T2D association results (additive model) of 152 SNPs for stage 1 case- control samples subset by metabolic syndrome status in cases --- p.144 / Chapter Appendix 5: --- T2D association results (additive model) of 22 SNPs for stage 2 case- control samples --- p.151 / Chapter Appendix 6: --- T2D association results (additive model) of 22 SNPs for stage 2 case- control samples subset by metabolic syndrome status in cases --- p.153

The development of type 2 diabetes over time involves defects in insulin action and insulin secretion. Defects in insulin action alone can be compensated with appropriate hyperinsulinemia. However, the progressive loss of pancreatic beta-cell function leads eventually to the development of persistent hyperglycemia that characterizes type 2 diabetes. Insulin secretion patterns reflect two phases when beta-cells are exposed to acute and sustained glucose stimulation. Through the study and understanding of the roles of these two phases in the regulation of glucose homeostasis, it is clear that insulin must not only be secreted in sufficient amounts, but also at the right time. In type 2 diabetes, the timing and magnitude of insulin secretion are altered, and an abnormal first-phase release initiates before the onset of the disease. Only a few pharmacokinetic/pharmacodynamic (PK/PD) models have considered the biphasic nature of insulin secretion. This study is aimed at describing the biphasic dynamics of insulin secretion through developing a PK/PD model based on current knowledge of the cellular mechanism of biphasic insulin secretion. The objectives of this work are to 1) evaluate the insulin-glucose kinetics using nonparametric analysis, 2) develop a physiologically based mechanistic PK/PD model to dynamically describe the biphasic insulin secretion, 3) evaluate the impact of ethnicity on insulin secretion kinetics following an intravenous glucose administration using population analysis and 4) extend the proposed model to oral glucose administration and utilize the co-secretion kinetics of insulin and C-peptide in a population PK/PD analysis of the prehepatic insulin secretion. Population analysis was done using a nonlinear mixed-effects model combined with the proposed PK/PD model to estimate population parameters and their variations between- and within-subjects and the covariates' effects on model parameters. The proposed model describes biphasic insulin behavior, accounts for first-phase insulin secretion, and also applies to oral glucose administration for estimating prehepatic insulin secretion in vivo and in liver extraction. This is done by an analysis that simultaneously uses plasma insulin and C-peptide concentrations. A significant higher first-phase insulin secretion was identified in healthy youths of African-American compared to Caucasians. The analysis showed no significant differences in the clearance of insulin from the plasma and the liver extraction of insulin between subjects with various levels of glucose tolerance. Obesity leads to a higher insulin production rate and lower elimination rate from the plasma than normal weight subjects. Also, type 2 diabetes and impaired glucose tolerance were found to reduce insulin production rate and resulted in a delayed insulin secretion from the beta-cells.

cAMP and Ca2+ are key regulators of exocytosis in many cells, including insulin-secreting pancreatic β-cells. Glucose-stimulated insulin secretion from β-cells is pulsatile and driven by oscillations of the cytoplasmic Ca2+ concentration ([Ca2+]i), but little is known about the kinetics of cAMP signaling and the mechanisms of cAMP action. Evanescent wave microscopy and fluorescent translocation biosensors were used to monitor plasma membrane-related signaling events in single MIN6-cells and primary mouse β-cells. Glucose stimulation of insulin secretion resulted in pronounced oscillations of the membrane phospholipid PIP3 caused by autocrine activation of insulin receptors. Glucose also triggered oscillations of the sub-plasma membrane cAMP concentration ([cAMP]pm). These oscillations were preceded and enhanced by elevations of [Ca2+]i, but conditions raising cytoplasmic ATP triggered [cAMP]pm elevations without accompanying changes in [Ca2+]i. The [cAMP]pm oscillations were also synchronized with PIP3 oscillations and both signals were suppressed after inhibition of adenylyl cyclases. Protein kinase A (PKA) was important for promoting concomitant initial elevations of [cAMP]pm and [Ca2+]i, and PKA inhibitors diminished the PIP3 response when applied before glucose stimulation, but did not affect already manifested PIP3 oscillations. The glucose-induced PIP3 oscillations were markedly suppressed in cells treated with siRNA against the cAMP-dependent guanine nucleotide exchange factor Epac2. Pharmacological activation of Epac restored PIP3 responses after adenylyl cyclase or PKA inhibition. Glucose and other cAMP-elevating stimuli induced redistribution of fluorescence-tagged Epac2 from the cytoplasm to the plasma membrane. This translocation was modulated by [Ca2+]i and depended on intact cyclic nucleotide-binding and Ras-association domains. In conclusion, glucose generates cAMP oscillations in β-cells via a concerted action of Ca2+ and metabolically generated ATP. The oscillations are important for the magnitude and kinetics of insulin secretion. While both protein kinase A and Epac is required for initiation of insulin secretion the cAMP-dependence of established pulsatility is mediated by Epac2.