Le pancréas est impliqué dans la digestion alimentaire et le contrôle glycémique. Cette diversité fonctionnelle repose sur des facteurs transcriptionnels et épigénétiques qui assurent une régulation coordonnée de l’identité et de la fonction des cellules. Ma thèse vise à caractériser le rôle de certains de ces facteurs. Nous avons précédemment montré le rôle de Hnf1b dans le développement du pancréas. Nous montrons que son inactivation post-natale chez la souris induit de graves défauts canalaires ainsi qu’une pancréatite associée à des néoplasies intra-épithéliales. La pathologie MODY5 est liée à des mutations de HNF1B. Nous avons analysé un modèle murin du MODY5 généré par insertion d’une mutation humaine chez la souris. Notre étude montre que ces souris constituent un bon modèle de la maladie. Elles sont intolérantes au glucose et présentent une réduction du volume total des gros ilots et des cellules bêta. Sur le plan exocrine, elles développent une pancréatite. Nos analyses suggèrent une étiologie embryonnaire. Antérieurement, notre équipe a montré le rôle des HDACs dans le développement du pancréas. Basés sur l’analogie des voies qui régulent développement et régénération du pancréas, nous avons étudié le rôle des HDACs dans la régénération pancréatique. Nous montrons que l’inactivation de HDAC3 sensibilise le tissu acinaire à l’inflammation et abroge sa régénération. Nos études dévoilent l’implication de nouveaux mécanismes moléculaires dans la survenue de la pancréatite, du cancer du pancréas et du diabète. Ces données pourront contribuer à l’identification de nouvelles cibles thérapeutiques pour le traitement ou la prévention des pathologies du pancréas. / The pancreas is crucial for food digestion and glycemic control. Its functional diversity is based on transcriptional and epigenetic factors which ensure the regulation of cellular identity and function. My thesis aims to characterize the role of some of these factors. We previously showed that Hnf1b is required for pancreas development. We show here that Hnf1b post-natal inactivation in mouse leads to strong ductal defects and pancreatitis associated with intraepithelial neoplasia. In human, HNF1B heterozygous mutations cause the MODY5 pathology. We analyzed a unique MODY5 mouse model generated by insertion of human mutation in mouse. We show that these mice constitute a valuable model of the disease. They are glucose intolerant and display reduced total volume of large islets and beta-cells. The exocrine compartment is also altered as mice develop a pancreatitis phenotype. Our analyses suggest an embryonic etiology. Previously, our team revealed HDAC roles in pancreas development. Pancreas regeneration and pancreas development sharing common molecular pathways, we investigated the role of HDACs in pancreas regeneration. We found that HDAC3 inactivation sensitizes acinar tissue to inflammation and prevents its regeneration. Our studies reveal new molecular mechanisms implied in the development of pancreatitis, pancreatic cancer and diabetes. These data could contribute to the identification of new therapeutic targets for the treatment of pancreatic pathologies.

Heterozygous mutations in the transcription factor, hepatocyte nuclear factor 1B (HNF1B), result in multisystem disease including diabetes due to beta-cell dysfunction and pancreatic hypoplasia. However, the mechanisms that underlie development of diabetes in HNF1B mutation carriers are still not fully understood due to lack of an appropriate model system. Human induced pluripotent stem cells (hiPSCs), which are capable of self-renewal and can differentiate into any cell type, provide an advantageous alternative to model human developmental diseases. The aim of this project was to develop a hiPSC based model system to determine the molecular mechanisms by which HNF1B mutations cause pancreatic hypoplasia and diabetes. HNF1B mutant hiPSC lines were produced using CRISPR-Cas9 genome editing. Isogenic HNF1B wild-type, homozygous and heterozygous mutant hiPSC lines were directed to differentiate along the pancreatic lineage and cells were phenotyped at each stage of the differentiation process to check for appropriate expression of lineage markers. The normal expression pattern of HNF1B in human pancreas development was analysed and showed up-regulation of HNF1B at the foregut stage, and during pancreas specification. Homozygous knockout of HNF1B resulted in failure of foregut and pancreatic progenitor development, while heterozygous knockout of HNF1B resulted in impairment of pancreatic progenitor and endocrine cell differentiation as well as impaired insulin secretion upon glucose stimulation. Cell proliferation analyses showed a significant decrease in the proliferation rate in HNF1B heterozygous and homozygous mutant cells compared with wild-type cells at the foregut stage while no change in the apoptosis rate could be detected. RNA-sequencing and ATAC-sequencing, were used to further define the molecular mechanisms controlled by HNF1B and the effect HNF1B on modulation of chromatin accessibility during pancreas development. These results provide further insights into the molecular mechanisms by which HNF1B regulates human pancreas development and function, revealing that HNF1B haploinsufficiency impairs the expansion and maintenance of pancreatic progenitor cells in vitro. In vivo, this would likely result in reduced beta cell numbers at birth and diabetes later in life in patients with HNF1B-associated disease. These mechanisms suggest that the capacity to produce pancreatic progenitor cells during embryonic life could determine individual susceptibility to diabetes.

Heterozygous mutations and deletions of the gene that encodes the transcription factor hepatocyte nuclear factor 1β (HNF1B) are the commonest known monogenic cause of developmental kidney disease. However, diagnosis remains challenging due to phenotypic variability and frequent absence of a family history. There is also no consensus as to when HNF1B genetic testing should be performed. This thesis includes work looking at the identification of HNF1B-associated disease. An HNF1B score was developed in 2014 to help select appropriate patients for genetic testing. The aim in chapter 2 was to test the clinical utility of this score in a large number of referrals for HNF1B genetic testing to the UK diagnostic testing service for the HNF1B gene. An HNF1B score was assigned for 686 referrals using clinical information available at the time of testing; performance of the score was evaluated by receiver-operating characteristic curve analysis. Although the HNF1B score discriminated between patients with and without a mutation/deletion reasonably well, the negative predictive value of 85% reduces its clinical utility. HNF1B-associated disease is due to an approximate 1.3 Mb deletion of chromosome 17q12 in about 50% of individuals. This deletion includes HNF1B plus 14 additional genes and has been linked to an increased risk of neurodevelopmental disorders, such as autism. The aim in chapter 3 was to compare the neurodevelopmental phenotype of patients with either an HNF1B intragenic mutation or 17q12 deletion to determine whether haploinsufficiency of the HNF1B gene is responsible for this aspect of the phenotype. Brief behavioural screening showed high levels of psychopathology and impact in children with a deletion. 8/20 (40%) patients with a deletion had a clinical diagnosis of a neurodevelopmental disorder compared to 0/18 with a mutation, P=0.004. 17q12 deletions were also associated with more autistic traits. Two independent clinical geneticists were able to predict the presence of a deletion with a sensitivity of 83% and specificity of 79% when assessing facial dysmorphic features as a whole. These results demonstrate that the 17q12 deletion but not HNF1B intragenic mutations are associated with neurodevelopmental disorders; we conclude that the HNF1B gene is not involved in the neurodevelopmental phenotype of these patients. Extra-renal phenotypes frequently occur in HNF1B-associated disease, including diabetes mellitus and pancreatic hypoplasia. Faecal elastase-1 levels have only been reported in a small number of individuals, the majority of which have diabetes. In chapter 4 we measured faecal elastase-1 in patients with an HNF1B mutation or deletion regardless of diabetes status and assessed the degree of symptoms associated with pancreatic exocrine deficiency. We found that faecal elastase-1 deficiency is a common feature of HNF1B-associated renal disease even when diabetes is not present and pancreatic exocrine deficiency may be more symptomatic than previously suggested. Faecal elastase-1 should be measured in all patients with a known HNF1B molecular abnormality complaining of chronic abdominal pain, loose stools or unintentional weight loss. Hypomagnesaemia is a common feature of HNF1B-associated disease and is due to renal magnesium wasting. The aim in chapter 5 was to measure both serum and urine magnesium and calcium levels in individuals with an HNF1B molecular defect and compare to a cohort of patients followed up in a general nephrology clinic in order to assess their potential as biomarkers for HNF1B-associated disease. The results of this pilot study show that using a cut-off for serum magnesium of ≤0.75 mmol/L was 100% sensitive and 87.5% specific for the presence of an HNF1B mutation/deletion. All individuals in the HNF1B cohort had hypermagnesuria with fractional excretion of magnesium >4%; a cut-off of ≥4.1% was 100% sensitive and 71% specific. This suggests serum magnesium levels and fractional excretion of magnesium are highly sensitive biomarkers for HNF1B-associated renal disease; if these results are confirmed in a larger study of patients with congenital anomalies of the kidneys or urinary tract they could be implemented as cheap screening tests for HNF1B genetic testing in routine clinical care.

Les mutations hétérozygotes du gène codant pour le facteur de transcription HNF1B sont à l'origine d'un syndrome multisystémique complexe connu sous le nom de « Renal Cysts and Diabetes » (RCAD). Un modèle de souris généré dans notre laboratoire s'est avéré reproduire plusieurs caractéristiques de la maladie humaine. Nous avons réalisé un séquençage ARNm-microARN à différents stades de développement (E14,5 ; E15,5 ; E17,5) de ce modèle. Nous avons montré que les gènes les plus dérégulés étaient impliqués dans les processus métaboliques de transport, de lipides et d’acides organiques et étaient exprimés dans les tubules proximaux et, dans une moindre mesure, dans l’anse de Henlé et les canaux collecteurs. Nous avons sélectionné quatre microARN (miR-802, 194-2, 192 et -30a), régulés à la baisse et potentiellement contrôlés par HNF1B. Des expériences de transactivation de gène rapporteur dans des cellules HEK-293 ont montré que HNF1B était capable de transactiver la transcription de ces microARN via des sites de liaison présents dans les séquences régulatrices de ces gènes. En utilisant des microARN MIMICS nous avons par la suite montré que mir-802, mir-194-2 et mir-192 étaient capables d'inhiber l’expression d’un gène rapporteur contenant la région 3'UTR de HNF1B. L'analyse d'échantillons d'urine de 22 patients RCAD et de 22 contrôles sains a permis d'identifier 146 peptides excrétés de manière différentielle et associés au syndrome. En utilisant ces résultats dans un modèle mathématique, classificateur prédit efficacement le syndrome RCAD avec une sensibilité de 91.7% et une spécificité de 91.1% sur une large population de patients. / Heterozygous mutations in the gene encoding the transcription factor HNF1B are the cause of a complex multisystem syndrome known as Renal Cysts And Diabetes (RCAD). A mouse model generated in our laboratory was shown to reproduce several features of the human disease. We performed high-throughput mRNA-microRNA sequencing at different developmental stages (E14.5, E15.5, E17.5). We showed that the most down-regulated genes were involved in transport, lipid and organic acid metabolic processes and expressed in proximal tubules and to a lesser extent in the loop of Henle and collecting ducts. We then selected four microRNAs (mir-802, 194-2, 192 and -30a), which were down-regulated and potentially controlled by HNF1B. Luciferase assays in HEK-293 cells showed that HNF1B was able to specifically transactivate in a dose response mode these microRNAs through binding HNF1B-binding sites in their regulatory promoter/enhancer upstream sequences. We subsequently showed by luciferase assays using miRNA MIMICS that mir-802, mir-194-2 and mir-192 were able to inhibit luciferase vectors containing the 3’UTR of Hnf1b. Analysis of urine samples from 22 RCAD patients and 22 healthy controls led to the identification of 146 peptides differentially excreted and associated with RCAD including a similarity regarding collagen and uromodulin fragments with the RCAD mouse model. Combining the peptides into a mathematical model we used independent cohorts of patients to validate the prediction of the RCAD syndrome. Our classifier efficiently predicted RCAD syndrome with 91.7% sensitivity and 91.1% specificity on a wide population.

Oncogenes drive cancer by hijacking normal cellular functions involved in proliferation and survival. Suppression of the driving oncogene is highly effective for promoting tumor regression, a phenomenon termed "oncogenic addiction." By using unbiased genetic tools to functionally probe oncogenic addiction, we can identify cancer dependencies and characterize aspects of oncogenic signaling.

Introduction HNF1B is a tissue-specific transcription factor, which plays a crucial role in the embryological development of a number of organs, especially kidneys, gastrointestinal system, pancreas and billiary system. While the significance of HNF1B in the development of urinary tract malformations has already been well described, its role in the pathogenesis of solid tumors has not yet been elucidated. Based on the current data it seems that depending on the type of individual tumor HNF1B can either act as an oncogene or a tumor suppressor. However, the precise mechanism of how it exerts its influence is still unclear. Aims: The thesis focuses on expanding the knowledge of the significance of HNF1B changes in selected solid tumors and non-neoplastic lesions. The individual goals include: 1) determining the role which HNF1B plays in the pathogenesis of these lesions, 2) evaluating the significance of HNF1B for differential diagnosis, 3) analysis of the prognostic and predictive meaning of HNF1B, 4) mutation analysis of the HNF1B gene in all the tumor and non-tumor tissues with the aim to identify novel pathogenic mutations, 5) methylation analysis of the HNF1B promoter. Material and methods: Immunohistochemical examination with the antibody against HNF1B was performed on 516 samples of tumor and...

Background: Type 2 diabetes is thought to result from interactions between genetic and lifestyle factors, but few robust examples exist. The overarching aim of this thesis was to discover such interactions by studying cohorts of white youth and adults from northern Europe in which physical activity, genotypes, and diabetes-related traits or diabetes incidence had been ascertained.   Methods: The thesis includes four papers. In Paper I, we investigated associations and interactions between 35 common PPARGC1A polymorphisms and cardiovascular and metabolic disease traits in 2,101 Danish and Estonian children from the European Youth Heart Study (EYHS). Paper II used the same cohort to test associations and interactions on cardiometabolic traits for the diabetes-predisposing TCF7L2 polymorphism. In Paper III, we assessed associations for 17 type 2 diabetes gene polymorphisms on impaired glucose regulation (IGR) or incident type 2 diabetes, and tested whether these effects are modified by physical activity in a prospective cohort study of ~16,000 initially non-diabetic Swedish adults – the Malmö Preventive Project (MPP). Paper IV aimed to replicate main genetic effects and gene x physical activity interactions for an FTO polymorphism on obesity in 18,435 primarily non-diabetic Swedish (MPP) and Finnish (Prevalence, Prediction and Prevention of Diabetes in Botnia) adults. Results: In Paper I, nominally significant associations were observed for BMI (rs10018239, P=0.039), waist circumference (rs7656250, P=0.012; rs8192678 [Gly482Ser], P=0.015; rs3755863, P=0.02; rs10018239, P=0.043), systolic blood pressure (rs2970869, P=0.018) and fasting glucose concentrations (rs11724368, P=0.045). Stronger associations were observed for aerobic fitness (rs7656250, P=0.005; rs13117172, P=0.008) and fasting glucose concentrations (rs7657071, P=0.002). None remained significant after correcting for multiple statistical comparisons. We proceeded by testing for gene × physical activity interactions for the polymorphisms that showed statistical evidence of association (P<0.05) in the main effect models, but none was statistically significant. In Paper II, the minor T allele at the rs7903146 variant was associated with higher glucose levels in older (beta=–0.098 mmol/l per minor allele copy, P=0.029) but not in younger children (beta=–0.001 mmol/l per minor allele copy, P=0.972). A significant inverse association between the minor allele at rs7903146 and height was evident in boys (beta=–1.073 cm per minor allele copy, P=0.001), but not in girls. The test of interaction between the TCF7L2 rs7903146 variant and physical activity on HOMA-B was nominally statistically significant (beta=0.022, Pinteraction=0.015), whereby physical activity reduced the effect of the risk allele on estimated beta-cell function. In Paper III, tests of gene x physical activity interactions on IGR-risk for three polymorphisms were nominally statistically significant: CDKN2A/B rs10811661 (Pinteraction=0.015); HNF1B rs4430796 (Pinteraction=0.026); PPARG rs1801282 (Pinteraction=0.04). Consistent interactions were observed for the CDKN2A/B (Pinteraction=0.013) and HNF1B (Pinteraction=0.0009) variants on 2 hr glucose concentrations. Where type 2 diabetes was the outcome, only one statistically significant interaction effect was observed and this was for the HNF1B rs4430796 variant (Pinteraction=0.0004). The interaction effects for HNF1B on 2 hr glucose and incident diabetes remained significant after correction for multiple testing (Pinteraction=0.015 and 0.0068, respectively). In Paper IV, the minor A allele at rs9939609 was associated with higher BMI (P<0.0001). The tests of gene x physical activity interaction on BMI were not statistically significant in either cohort (Sweden: P=0.71, Finland: P=0.18). Conclusions: Variation at PPARGC1A is unlikely to have a major impact on cardiometabolic health in European children, but physical activity may modify the effect of the TFC7L2 variants on beta-cell function in this cohort. In Swedish adults, physical activity modifies the effects of common HNF1B and CDKN2A/B variants on risk of IGR and also modifies the effect of the HNF1B on type 2 diabetes risk. In Swedish and Finnish adults, we were unable to confirm previous reports of an interaction between FTO gene variation and physical activity on obesity predisposition.

Diss. (sammanfattning) Umeå : Umeå universitet, 2010. / Härtill 4 uppsatser. Även tryckt utgåva.

Autosomal recessive polycystic kidney disease (ARPKD) is a rare severe inherited disease manifested by cystic renal disease, congenital hepatic fibrosis and dilatatation of bile ducts. The spectrum of clinical manifestations is very wide and variable, depends on the age at which the disease was manifested. In severe forms of the disease, it is possible to detect the first symptoms prenatally around the 20th week of pregnancy due to increased echogenic kidneys and the presence of oligohydramnios. The causal gene of this disease is thePKHD1 gene with protein product fibrocystin that is most likely contributing on maintaining the intracellular concentration of Ca2+ cations. The exact phatophysiology mechanism of ARPKD remains unknown. Phenotypic manifestations of this disease may overlap with mutations associated with other genes. One of the genes mimicking the ARPKD phenotype is the HNF1B gene. Mutations associated with HNF1B gene are the most common monogenic cause of developmental kidney abnormalities. HNF1B is a tissue-specific transcription factor that regulates the expression of PKHD1. In experimental part I worked on genetic analysis of the HNF1B gene in 28 patients who have not been confirmed ARPKD diagnosis by detection of 2 PKHD1 mutations. For the purposes of mutational screening, I used...