京都大学 / 0048 / 新制・課程博士 / 博士(人間・環境学) / 甲第19806号 / 人博第777号 / 新制||人||187(附属図書館) / 27||人博||777(吉田南総合図書館) / 32842 / 京都大学大学院人間・環境学研究科共生人間学専攻 / (主査)教授 林 達也, 教授 森谷 敏夫, 教授 石原 昭彦 / 学位規則第4条第1項該当 / Doctor of Human and Environmental Studies / Kyoto University / DGAM

Par l'entremise d'un modèle de souris transgénique exprimant une forme mutée et inactive d'AMPKa2 (KD), cette étude avait comme principal objectif de tester le rôle de l'AMPK dans le transport de glucose stimulé par la contraction musculaire. Un protocole de stimulation électrique a été défini pour assurer une génération de force égale entre l'extenseur digitorum longus (EDL) de souris KD et son contrôle sauvage (SA). Nous avons observé que le transport de glucose est réduit de 70% dans l'EDL de souris KD. Une cible protéique a aussi été identifiée comme étant modulée par l'AMPK lors de la contraction musculaire, soit la p38 MAPK. L'activité de p38 MAPK n'est pas modulée lors de la contraction musculaire chez la souris KD, contrairement à la souris SA. Le niveau d'ARNm de l'hexokinase II (HKII) est diminué chez la souris KD. Il est donc postulé qu'AMPK est un activateur essentiel de la p38 MAPK, ce qui pourrait contribuer à l'augmentation du transport de glucose par la contraction et à la modulation du niveau d'ARNm d'HKII cellulaire. On suggère que p38 MAPK pourrait induire l'ARNm d'HKII par l'entremise de CREB, un facteur reconnu pour être impliqué dans la transcription d'HKII.

The intestinal epithelium is able to adapt to varying blood flow and, thus, oxygen availability. Still, the adaptation fails under pathologic situations. A better understanding of the mechanisms underlying the epithelial adaptation to hypoxia could help to improve the therapeutic approach. We hypothesized that the short-term adaptation to hypoxia is mediated via AMP-activated protein kinase (AMPK) and that it is coupled to the long-term adaptation by a common regulation mechanism, the HIF-hydroxylase enzymes. Further, we hypothesized the transepithelial transport of glucose to be part of this short-term adaptation. We conducted Ussing chamber studies using isolated lagomorph jejunum epithelium and cell culture experiments with CaCo-2 cells. The epithelia and cells were incubated under 100% and 21% O2, respectively, with the panhydroxylase inhibitor dimethyloxalylglycine (DMOG) or under 1% O2. We showed an activation of AMPK under hypoxia and after incubation with DMOG by Western blot. This could be related to functional effects like an impairment of Na+-coupled glucose transport. Inhibitor studies revealed a recruitment of glucose transporter 1 under hypoxia, but not after incubation with DMOG. Summing up, we showed an influence of hydroxylase enzymes on AMPK activity and similarities between hypoxia and the effects of hydroxylase inhibition on functional changes.

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The glucose transport protein, GLUT1, is highly expressed in rapidly proliferating cells, including cancer cells, while decreased GLUT1 levels are found in diseases such as GLUT1 deficiency syndrome and Alzheimer’s. There is increased interest in developing GLUT1 inhibitors as novel anticancer therapeutics, and the discovery of compounds that directly stimulate GLUT1 function. This work investigates how small molecules stimulate and/or inhibit GLUT1-mediated glucose transport, either directly or through the AMPK pathway. Using sugar transport assays and docking analyses to explore Ligand–GLUT1 interactions and specificity of binding, we show that: 1) Ligands inhibit GLUT1 by competing with glucose for binding to the exofacial or endofacial sugar binding sites; 2) Subsaturating inhibitor concentrations stimulate sugar uptake; 3) Ligands inhibit GLUT1–, GLUT3– and GLUT4–mediated sugar uptake in HEK293 cells; and 4) Inclusion of a benzonitrile head group on endofacial GLUT1 inhibitors confers greater inhibitory potency. Furthermore, we investigated AMPK-regulated GLUT1 trafficking in cultured blood-brain barrier endothelial cells, and show that inhibition of GLUT1 internalization is not responsible for increased cell surface levels of GLUT1 observed with AMPK activation in these cells. This study provides a framework for screening candidate GLUT1 inhibitors for specificity, and for optimizing drug design and delivery. Our data on transport stimulation at low inhibitor concentrations support the idea that GLUT1 functions as a cooperative oligomer of allosteric alternating access subunits.

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Le DT2 est caractérise par un défaut combiné de la sécrétion et de l’action de l’insuline. Depuis près d’un demi siècle la chirurgie bariatrique et notamment le Roux-en-Y Gastric Bypass (RYGB) ont montré des effets spectaculaires sur le contrôle glycémique remettant en question le paradigme de la prise en charge médicale du DT2. L’exclusion gastro duodénale induite par le RYGB améliore le métabolisme glucidique indépendemment de la perte de poids. Ainsi les modifications du flux biliaire semblent jouer un rôle, cependant les mécanismes sous-jacents ne sont pas clairs. Nous avons réalisés des RYGB chez le miniporc et nous avons montré que l'absorption intestinale du glucose est diminuée dans l’anse alimentaire (AL) dépourvue de bile. L'absorption du glucose dans l’AL était restaurée par l'ajout de la bile, et cet effet était inhibé lorsque le co transport actif sodium glucose 1 (SGLT1) était bloquée par la phlorizine. SGLT1 restait exprimée dans la AL, cependant la teneur dans la lumière de l’intestin en sodium était nettement diminuée. L’ajout de sodium dans l'AL provoquait le même effet que la bile sur l'absorption du glucose et augmentait également l’excursion glycémique post prandiale chez le miniporc au cours d’un repas test vigil. La diminution de l'absorption intestinale du glucose après RYGB a ensuite été confirmée chez l'homme. Nos résultats démontrent que la l’exclusion biliaire affecte le métabolisme post prandiale du glucose par modulation des co transporteurs intestinaux sodium-glucose. / Type 2 diabetes (T2D) is characterized primarily as a combined defect of insulin secretion and insulin action. For nearly a decade, the somewhat mysterious but spectacular benefit of metabolic surgery, and more specifically of Roux-en-Y gastric bypass (RYGB), on glucose control has been caused a questioning the current paradigm of T2D management. Gastro-intestinal exclusion by RYGB improves glucose metabolism, independent of weight loss. Although changes in intestinal bile trafficking have been shown to play a role, the underlying mechanisms are unclear. We performed RYGB in minipigs and showed that the intestinal uptake of ingested glucose is blunted in the bile deprived alimentary limb (AL). Glucose uptake in the AL was restored by the addition of bile, and this effect was abolished when active glucose intestinal transport was blocked with phlorizin. Sodium-glucose cotransporter 1 remained expressed in the AL, while intraluminal sodium content was markedly decreased. Adding sodium to the AL had the same effect as bile on glucose uptake. It also increased postprandial blood glucose response in conscious minipigs following RYGB. The decrease in intestinal uptake of glucose after RYGB was confirmed in humans. Our results demonstrate that bile diversion affects postprandial glucose metabolism by modulating sodium-glucose intestinal cotransport.

Le diabète de type 2 et l'obésité sont des problèmes de santé majeurs et les peuples autochtones sont particulièrement à risque. Pour remédier à ce problème largement répandu dans les populations autochtones canadiennes pour qui la médication moderne n’est pas culturellement adaptée, notre équipe s’est donné comme objectif d’étudier les activités potentielles antidiabétique et anti-obésité de la pharmacopée traditionnelle des Cris de la Baie James. Le but de cette étude est de tester l’hypothèse selon laquelle certaines plantes médicinales pourraient inhiber l'absorption intestinale du glucose, une activité anti-hyperglycémique qui, par la même occasion, contribuerait à combattre l’obésité. Les extraits éthanoliques de dix-sept plantes médicinales de la forêt boréale ont été testés dans des cellules intestinales Caco-2 et comparés à l’effet d’inhibiteurs compétitifs connus, tels que la phlorizine et la phlorétine. Ces inhibiteurs sont des composés polyphénoliques qui partagent de nombreuses caractéristiques structurelles avec des constituants moléculaires de plusieurs plantes Cri. Les résultats démontrent que treize des dix-sept extraits de plantes ont inhibé de façon significative l'absorption intestinale du 3H-D-glucose. Pour valider ces effets in vivo, quatre extraits ont été administrés à des rats Wistar par gavage intragastrique (250 mg/kg) en même temps qu’un bolus de glucose (3 g/kg). Suite à ce gavage, deux de ces extraits ont restreint l’augmentation de la glycémie d'environ 40% par rapport à un contrôle sans extrait. Ces résultats indiquent qu’une inhibition compétitive de l'absorption intestinale du glucose peut être atteinte par des extraits bruts de plantes médicinales. La prise de ces plantes durant les repas aiderait à un meilleur contrôle post-prandial de la glycémie, particulièrement chez les personnes à risque. / Type II diabetes and obesity are major health problems worldwide and aboriginal peoples are particularly at risk. To address this problem in Canadian native populations for whom modern pharmaceuticals are culturally misadapted, our team is testing the traditional pharmacopeia of the James Bay Cree for anti-diabetic and anti-obesity activities. More specifically, the aim of the present study was to define the effects of traditional plants on intestinal glucose absorption, an under-appreciated anti-hyperglycaemic and anti-obesity activity. Crude ethanol extracts of seventeen Boreal forest medicinal plants were examined in the Caco-2 human enterocytic cell line and compared to the competitive classical inhibitors phlorizin and phloretin. It is worth noting that the latter compounds are polyphenols that share many structural characteristics with components of several Cree plants. Thirteen of seventeen extracts were observed to significantly inhibit uptake when administered simultaneously with 3H-deoxyglucose. Inhibition was dose-dependent and, in a few cases, even surpassed that induced by a combination of the positive controls. To validate these effects in-vivo, four plant extracts were administered by intragastric gavage at 250 mg/kg to normal rats simultaneously with a 3 g/kg bolus of glucose. This resulted in a decrease in peak glycaemia by approximately 40% for two of them. These findings indicate that competitive inhibition of facilitative intestinal glucose uptake can be achieved by crude extracts of medicinal plants. Intake of the latter with meals may help control post-prandial glycaemia and reduce caloric intake in high risk populations.

O diabetes melito gestacional (DMG) está relacionado ao crescimento fetal exagerado. Entender a influência de fatores relacionados ao crescimento fetal auxilia na identificação dos fetos com maior risco de desvios da normalidade. Objetivo: comparar fatores clínicos, laboratoriais e a expressão placentária de transportadores de glicose segundo o crescimento fetal em pacientes com DMG. Método: Para análise dos fatores clínicos e laboratoriais foi realizado um estudo retrospectivo com 425 gestantes com DMG do Setor de Endocrinopatias da Divisão de Clínica Obstétrica do Hospital das Clínicas da Faculdade de Medicina da Universidade de São Paulo (HC FM-USP) no período de janeiro de 2003 a novembro de 2009. Para a análise da expressão placentária dos transportadores de glicose dos tipos 1 (GLUT1), 3 (GLUT3) e 4 (GLUT4) foram selecionados todos os casos de recém-nascidos grandes para idade gestacional (RNGIG) pareados com um caso controle de recém-nascido adequado para idade gestacional (RNAIG). Foram incluídas apenas gestações únicas e com DMG diagnosticado pelo teste de tolerância à glicose oral de 100 gramas, sem malformações fetais e com idade gestacional definida e confiável. Todas as gestantes realizaram dieta para diabetes, controle glicêmico diário e uso de insulina quando necessário. Os critérios de seguimento e tratamento seguiram rigorosamente as normas do Protocolo de Condutas do Setor de Endocrinopatias da Divisão de Clínica Obstétrica do HC-FMUSP. As gestantes foram divididas para análise dos dados em dois grupos: Fatores clínicos e laboratoriais com: 376 RNAIG e 49 RNGIG num total de 425 DMG. Expressão Placentária dos Transportadores de Glicose: 50 RNAIG e 44 RNGIG. Foram realizados testes de associação e médias das variáveis e relacionadas com os grupos de RNAIG e RNGIG. Resultados: Na análise univariada, dos fatores clínicos e laboratoriais, não houve diferenças entre os grupos quanto a: idade materna, antecedente familiar de diabetes, antecedente pessoal de hipertensão arterial, número de gestações, valores de glicemia de jejum e 1 hora no TTGO-100g, idade gestacional no parto, sexo do RN, tipo de parto e índice de Apgar no 1º e 5º minutos. Houve diferenças estatisticamente significativas entre os grupos quanto a: índice de massa corpórea pré-gestacional (p < 0,02); uso de insulina (p < 0,041); macrossomia anterior (p < 0,001); idade gestacional do diagnóstico do DMG (p < 0,001); glicemias de duas e três horas no TTGO-100g respectivamente com (p < 0,003) e (p < 0,026). Na análise de regressão logística foram considerados preditores independentes da ocorrência de RNGIG: o índice de massa corpórea pré - gestacional, a macrossomia anterior, aidade gestacional do diagnóstico do DMG e a glicemia de duas horas após sobrecarga de 100 gramas. Em relação a expressão dos transportadores de glicose não diferiram entre os grupos em relação a expressão de GLUT1 na decídua, GLUT3 na decídua e vilosidades e GLUT4 na decídua e vilosidades. Houve diferença entre os grupos quanto à: a expressão do GLUT1 nas vilosidades. Conclusões: O índice de massa corpórea pré - gestacional, a macrossomia anterior, a idade gestacional do diagnóstico do DMG e a glicemia de duas horas após sobrecarga de 100 gramas foram preditores da ocorrência de RNGIG. A expressão de GLUT1 nas vilosidades coriônicas teve relação com a ocorrência de RNGIG / Gestational diabetes mellitus (GDM) is related to excessive fetal growth. Knowing the influence of factors related to fetal growth assists in the identification of fetuses at high risk of deviations from normality. Objective: To compare clinical and laboratory tests and the placental expression of glucose transporters according to fetal growth in patients with GDM. Method: A retrospective study of clinical and laboratory factors related with large for gestational age newborns, included 425 pregnant women with GDM was carried out at Sector Endocrine Clinic of Obstetrics Hospital of the School of Medicine, University of São Paulo (HC-FMUSP), between January 2003 to November 2009. For the analysis of placental expression of glucose transporters types 1 (GLUT1), 3 (GLUT3) and 4 (GLUT4) were selected all cases of newborns large for gestational age (LGA) paired with a case control newly born appropriate for gestational age (AGA). We included only patients with singleton pregnancies and GDM diagnosed by OGTT-100g, with newborns without malformations and birth weight classified as adequate or large for gestational age. All pregnant women received diet for diabetes, daily glycemic control and insulin when necessary. The criteria for monitoring and treatment followed strictly the standards of Conduct Protocol Endocrine Obstetric Clinic of the Clinic Hospital, School of Medicine, University of São Paulo. The pregnancies were divided for analysis into two groups: 376 cases of newborns AGA and 49 cases of newborns LGA. Data were analyzed and considered the probability value p <0.05. Results: In the univariate analysis of clinical and laboratory factors, there were no differences between the groups regarding maternal age, family history of diabetes, personal history of hypertension, number of pregnancies, blood fasting glucose and 1 hour in- OGTT 100g, gestational age at delivery, gender of the newborn, type of delivery, Apgar score at 1st and 5th minutes. There were statistically significant differences between the groups regarding: body mass index before pregnancy (p <0.02), insulin (p <0.041), previous macrosomia (p <0.001), gestational age at diagnosis of GDM (p <0.001), blood glucose levels two and three hours at 100 g OGTT, respectively, with (p <0.003) (p <0.026). In logistic regression analysis were considered independent predictors of the occurrence of LGA: body mass index before pregnancy, previous macrosomia gestational age at diagnosis of GDM and two hours after glucose overload 100 grams. Regarding the expression of glucose transporters, the groups did not differ regarding the expression of GLUT1 in the decidua, GLUT3 in the decidua and villi and GLUT4 in the decidua and villi. There were differences between the groups regarding the expression of GLUT1 in the villi. Conclusions: The body mass index before pregnancy, previous macrosomia, gestational age of diagnosis of GDM and two hours after glucose overload 100 grams were predictors of the occurrence of LGA. The expression of GLUT1 in chorionic villi was related to the occurrence of LGA newborn