The role of the microRNAs in the age-associated oancreatic β-cell dysfunction

Le corps humain emploie le glucose comme source principale d'énergie. L'insuline, sécrétée par les cellules ß-pancreatiques situées dans les îlots de Langerhans, est l'hormone principale assurant un maintien constant du taux de glucose sanguin (glycémie). Les prédispositions génétiques, le manque d'activité physique et un régime déséquilibré peuvent entraîner une perte de sensibilité à l'insuline et des taux de glucose dans le sang élevé (hyperglycémie), une condition nommée diabète de type 2. Cette maladie est initiée par une sensibilité diminuée à l'insuline dans les tissus périphériques, entraînant une demande accrue en insuline. Cette pression continue finie par épuiser les cellules ß-pancreatiques, qui sécrètent alors des niveaux d'insuline insuffisant en trainant l'apparition du diabète. Le vieillissement est un facteur de risque important pour les maladies métaboliques dont le diabète de type 2 faits partis. En effet la majeure partie des diabétiques de type 2 ont plus de 45 ans. Il est connu que le vieillissement entraine une perte de sensibilité à l'insuline, une sécrétion altérée d'insuline, une baisse de réplication et une plus grande mort des ß-cellules pancréatiques. Le but de ma thèse était de mieux comprendre les mécanismes contribuante au dysfonctionnement des cellules ß- pancréatiques lors du vieillissement. Les travaux du « Human Genome Project » ont révélés que seulement 2% de notre génome code pour des protéines. Le reste non-codant fut alors désigné sous le nom de « ADN déchets ». Cependant, l'étude approfondie de cet ADN non-codant ces dernières deux décennies a démontré qu'une grande partie code pour des «MicroARNs », des ARNs courts (20-22 nucleotides) découverts en 1997 chez le vers C.elegans. Depuis lors ces molécules ont été intensivement étudiées, révélant un rôle crucial de ces molécules dans la fonction et la survie des cellules en conditions normales et pathologiques. Le but de cette thèse était d'étudier le rôle des microARNs dans le dysfonctionnement des cellules ß lors du vieillissement. Nos données suggèrent qu'ils peuvent jouer un rôle tantôt salutaire, tantôt nocif sur les cellules ß. Par exemple, certains microARNs réduisent la capacité des cellules ß à se multiplier ou réduisent leur survie, alors que d'autres protègent ces cellules contre la mort. Pour conclure, nous avons démontré les microARNs jouent un rôle important dans le dysfonctionnement des cellules ß lors du vieillissement. Ces nouvelles découvertes préparent le terrain pour la conception de futures stratégies visant à améliorer la résistance des cellules ß pancréatiques afin de trouver de nouveaux traitements du diabète de type 2. -- Le diabète de type 2 est une maladie métabolique due à la résistance à l'action de l'insuline des tissus cibles combinée à l'incapacité des cellules ß pancréatiques à sécréter les niveaux adéquats d'insuline. Le vieillissement est associé à un déclin global des fonctions de l'organisme incluant une diminution de la fonction et du renouvellement des cellules ß pancréatiques. Il constitue ainsi un risque majeur de développement des maladies métaboliques dont le diabète de type 2. Le but de cette thèse était d'étudier le rôle des microARNs (une classe d'ARN non- codants) dans le dysfonctionnement lié au vieillissement des cellules ß. L'analyse par microarray des niveaux d'expression des microARN dans les îlots pancréatiques de rats Wistar mâles âgés de 3 et 12 mois nous a permis d'identifier de nombreux changements d'expression de microARNs associés au vieillissement. Afin d'étudier les liens entre ces modifications et le déclin des cellules ß, les changements observés lors du vieillissement ont été reproduits spécifiquement dans une lignée cellulaire, dans des cellules ß primaires de jeune rats ou de donneurs humains sains. La diminution du miR-181a réduit la prolifération des cellules ß, tandis que la diminution du miR-130b ou l'augmentation du miR-383 protège contre l'apoptose induite par les cytokines. L'augmentation du miR-34a induit l'apoptose et inhibe la prolifération des cellules ß en réponse aux hormones Exendin-4 et prolactine et au facteur de croissance PDGF-AA. Cette perte de capacité réplicative est similaire à celle observée dans des cellules ß de rats âgés de 12 mois. Dans la littérature, la perte du récepteur au PDGF-r-a est associée à la diminution de la capacité proliférative des cellules ß observée lors du vieillissement. Nous avons pu démontrer que PDGF-r-a est une cible directe de miR- 34a, suggérant que l'effet néfaste de miR-34a sur la prolifération des cellules ß est, du moins en partie, lié à l'inhibition de l'expression de PDGF-r-a. L'expression de ce miR est aussi plus élevée dans le foie et le cerveau des animaux de 1 an et augmente avec l'âge dans les ilôts de donneurs non-diabétiques. Ces résultats suggèrent que miR-34a pourrait être non seulement impliqué dans l'affaiblissement des fonctions pancréatiques associé à l'âge, mais également jouer un rôle dans les tissus cibles de l'insuline et ainsi contribuer au vieillissement de l'organisme en général. Pour conclure, les travaux obtenus durant cette thèse suggèrent que des microARNs sont impliqués dans le dysfonctionnement des cellules ß pancréatiques durant le vieillissement. -- Type 2 diabetes is a metabolic disease characterized by impaired glucose tolerance, of the insulin sensitive tissues and insufficient insulin secretion from the pancreatic ß-cells to sustain the organism demand. Aging is a risk factor for the majority of the metabolic diseases including type 2 diabetes. With aging is observed a decline in all body function, due to decrease both in cell efficiency and renewal. The aim of this thesis was to investigate the potential role of microRNAs (short non- coding RNAs) in the pancreatic ß-cell dysfunction associated with aging. Microarray analysis of microRNA expression profile in pancreatic islets from 3 and 12 month old Wistar male rats revealed important changes in several microRNAs. To further study the link between those alterations and the decline of ß-cells, the changes observed in old rats were mimicked in immortalized ß-cell lines, primary young rat and human islets. Downregulation of miR-181a inhibited pancreatic ß-cell proliferation in response to proliferative drugs, whereas downregulation of miR-130b and upregulation of miR-383 protected pancreatic ß-cells from cytokine stimulated apoptosis. Interestingly, miR-34a augmented pancreatic ß-cell apoptosis and inhibited ß-cell proliferation in response to the proliferative chemicals Exendin-4, prolactin and PDGF-AA. This loss of replicative capacity is reminiscent of what we observed in pancreatic ß-cells isolated from 12 month old rats. We further observed a correlation between the inhibitory effect of miR-34a on pancreatic ß-cell proliferation and its direct interfering effect of this microRNA on PDGF-r-a, which was previously reported to be involved in the age-associated decline of pancreatic ß-cell proliferation. Interestingly miR-34a was upregulated in the liver and brain of 1 year old animals and positively correlated with age in pancreatic islets of normoglycemic human donors. These results suggest that miR-34a might be not only involved in the age-associated impairment of the pancreatic ß-cell functions, but also play a role in insulin target tissues and contribute to the aging phenotype on the organism level. To conclude, we have demonstrated that microRNAs are indeed involved in the age-associated pancreatic ß-cell dysfunction and they can play both beneficial and harmful roles in the context of pancreatic ß-cell aging.

Markers of iron metabolism and metabolic syndrome in Swiss adults

Plusieurs études populationnelles ont montré l'existence d'une association entre des taux sanguins élevés de transferrine et le syndrome métabolique (SM). Bien que cette association soit bien établie, restent encore à être décrites les associations entre le SM et les autres marqueurs sanguins du métabolisme du fer, tels que le fer, la transferrine (Tsf), la capacité totale de fixation de la transferrine (CTF) ou la saturation de la transferrine (SaTsf) sanguins. Le but de notre étude a été d'identifier les associations entre les différents marqueurs du métabolisme du fer (fer, ferritine, Tsf, CTF et SaTsf) et le SM. Les données de l'étude CoLaus, récoltées entre 2003 et 2006, ont été utilisées. Le SM était défini selon les critères du National Cholesterol Education Program Adult Panel III. L'analyse statistique a été faite en stratifiant selon le genre ainsi que le status ménopausal chez les femmes. Des 6733 participants, 1235 (18%) ont été exclus de fait d'absence de données concernant les variables qui nous intéressaient, ou chez qui nous avons soupçonné une possible hémochromatose non diagnostiquée (SaTsf> 50%). Des 5498 participants restant (âge moyen ± écart-type: 53 ± 11 ans), 2596 étaient des hommes, 1285 des femmes pré- et 1617 des femmes postménopausées. La prévalence du SM était de 29,4% chez les hommes, 8,3% et 25,5% chez les femmes pré- et postménopausées, respectivement. Dans les trois groupes, la prévalence du SM était la plus haute dans les quartiles les plus élevés de ferritine, Tsf et CTF, ainsi que dans le quartile le plus bas de SaTsf. Après ajustement sur l'âge, l'indice de masse corporelle, la protéine C réactive, la consommation de tabac et/ou d'alcool, la prise de suppléments en fer et les marqueurs hépatiques, l'appartenance au quartile le plus élevé de ferritine, Tsf ou CTF était associée à un risque plus important de SM chez les hommes et les femmes postménopausées : Odds ratio (OR) et [intervalle de confiance à 95%] pour la ferritine 1.44 [1.07-1.94] et 1.47 [0.99-2.17]; pour la Tsf et la CTF, OR=1.43 [1.06-1.91] et 2.13 [1.44-3.15] pour les hommes et les femmes postménopausées, respectivement. Au contraire, l'appartenance au quartile le plus élevé de la SaTsf était associé à un risque moins important de SM: OR=0.77 [0.57-1.05] et 0.59 [0.39-0.90] pour les hommes et les femmes postménopausées, respectivement. Il n'y avait aucune association entre les marqueurs sanguins du métabolisme du fer et le SM chez les femmes préménopausées, ni entre le fer sanguin et le SM chez les trois groupes. En conclusion, la majorité des marqueurs sanguins du métabolisme du fer, mais pas le fer lui-même, sont associés de manière indépendante au SM chez les hommes et les femmes postménopausées. -- Context: Excessive iron storage has been associated with metabolic syndrome (MS). Objective: To assess the association between markers of iron metabolism and MS in a healthy population. Design: Cross-sectional study conducted between 2003 and 2006. Setting: Population-based study in Lausanne, Switzerland. Patients: 5,498 participants aged 35-75 years, stratified by sex and menopausal status. Participants with transferrin saturation (TSAT) >50% were excluded. Intervention: None. Main Outcome Measures: serum iron, ferritin, transferrin, total iron binding capacity (TIBC) and TSAT. MS was defined according to ATP-III criteria. Results: Prevalence of MS was 29.4% in men, 8.3% in premenopausal and 25.5% in postmenopausal women. On bivariate analysis, the highest prevalence of MS occurred in the highest quartiles of serum ferritin, transferrin and TIBC, and in the lowest quartile of TSAT. After multivariate adjustment for age, body mass index, C-reactive protein, smoking, alcohol, liver markers and iron supplementation, men and postmenopausal women in the highest quartile of serum ferritin, transferrin and TIBC had a higher risk of presenting with MS: for ferritin, Odds ratio and [95% CI]=1.44 [1.07-1.94] for men and 1.47 [0.99-2.17] for postmenopausal women; for transferrin and TIBC, OR=1.43 [1.06-1.91] and 2.13 [1.44-3.15], Participants in the highest quartile of TSAT had a lower risk of MS: OR=0.77 [0.57-1.05] for men and 0.59 [0.39-0.90] for postmenopausal women. No association was found between iron and MS and between markers of iron metabolism and MS in premenopausal women. Conclusion: Ferritin, transferrin, TIBC are positively and TSAT is negatively associated with MS in men and postmenopausal women.

Metabolic syndrome and nonalcoholic fatty liver disease: Is insulin resistance the link?

Metabolic syndrome (MetS) is a disease composed of different risk factors such as obesity, type 2 diabetes or dyslipidemia. The prevalence of this syndrome is increasing worldwide in parallel with the rise in obesity. Nonalcoholic fatty liver disease (NAFLD) is now the most frequent chronic liver disease in western countries, affecting more than 30% of the general population. NAFLD encompasses a spectrum of liver manifestations ranging from simple steatosis to nonalcoholic steatohepatitis (NASH), fibrosis and cirrhosis, which may ultimately progress to hepatocellular carcinoma. There is accumulating evidence supporting an association between NAFLD and MetS. Indeed, NAFLD is recognized as the liver manifestation of MetS. Insulin resistance is increasingly recognized as a key factor linking MetS and NAFLD. Insulin resistance is associated with excessive fat accumulation in ectopic tissues, such as the liver, and increased circulating free fatty acids, which can further promote inflammation and endoplasmic reticulum stress. This in turn aggravates and maintains the insulin resistant state, constituting a vicious cycle. Importantly, evidence shows that most of the patients developing NAFLD present at least one of the MetS traits. This review will define MetS and NAFLD, provide an overview of the common pathophysiological mechanisms linking MetS and NAFLD, and give a perspective regarding treatment of these ever growing metabolic diseases.

Nrf2 Activation Promotes Keratinocyte Survival during Early Skin Carcinogenesis via Metabolic Alterations.

Pharmacologic activation of the transcription factor NRF2 has been suggested to offer a strategy for cancer prevention. In this study, we present evidence from murine tumorigenesis experiments suggesting there may be limitations to this possibility, based on tumorigenic effects of Nrf2 in murine keratinocytes that have not been described previously. In this setting, Nrf2 expression conferred metabolic alterations in keratinocytes that were protumorigenic in nature, affecting enzymes involved in glutathione biosynthesis or in the oxidative pentose phosphate pathway and other NADPH-producing enzymes. Under stress conditions, coordinate increases in NADPH, purine, and glutathione levels promoted the survival of keratinocytes harboring oncogenic mutations, thereby promoting tumor development. The protumorigenic activity of Nrf2 in keratinocytes was particularly significant in a mouse model of skin tumorigenesis that did not rely upon chemical carcinogenesis. In exploring the clinical relevance of our findings, we confirm that NRF2 and protumorigenic NRF2 target genes were activated in some actinic keratoses, the major precancerous lesion in human skin. Overall, our results reveal an unexpected tumor-promoting activity of activated NRF2 during early phases of skin tumorigenesis. Cancer Res; 75(22); 4817-29. ©2015 AACR.

Metabolic and nutritional support of critically ill patients: consensus and controversies.

The results of recent large-scale clinical trials have led us to review our understanding of the metabolic response to stress and the most appropriate means of managing nutrition in critically ill patients. This review presents an update in this field, identifying and discussing a number of areas for which consensus has been reached and others where controversy remains and presenting areas for future research. We discuss optimal calorie and protein intake, the incidence and management of re-feeding syndrome, the role of gastric residual volume monitoring, the place of supplemental parenteral nutrition when enteral feeding is deemed insufficient, the role of indirect calorimetry, and potential indications for several pharmaconutrients.

An unusual cause of high anion gap metabolic acidosis: pyroglutamic acidemia. A case report.

Pyroglutamic acidemia is an uncommon metabolic disorder, which is usually diagnosed at early ages. The mechanism of action is thought to be glutathione depletion, and its clinical manifestations consist of hemolytic anemia, mental retardation, ataxia, and chronic metabolic acidosis. However, an acquired form has been described in adult patients, who usually present with confusion, respiratory distress, and high anion gap metabolic acidosis (HAGMA). It is also associated with many conditions, including chronic acetaminophen consumption. A 68-year-old white male, with chronic acetaminophen use presented to our service on multiple occasions with severe HAGMA. The patient was admitted to the intensive care unit and required mechanical ventilation and aggressive supportive measures. After ruling out the most frequent etiologies for his acid-base disorder and considering the long history of Tylenol ingestion, his 5-oxiproline (pyroglutamic acid) levels were sent to diagnose pyroglutamic acidemia. Clinicians need to be aware of this cause for metabolic acidosis since it might be a more common metabolic disturbance in compromised patients than would be expected. Subjects with HAGMA that cannot be explained by common causes should be tested for the presence of 5-oxoproline. Discontinuation of the offending drug is therapeutic.

Evidence for hypothalamic ketone body sensing: impact on food intake and peripheral metabolic responses in mice.

Monocarboxylates have been implicated in the control of energy homeostasis. Among them, the putative role of ketone bodies produced notably during high-fat diet (HFD) has not been thoroughly explored. In this study, we aimed to determine the impact of a specific rise in cerebral ketone bodies on food intake and energy homeostasis regulation. A carotid infusion of ketone bodies was performed on mice to stimulate sensitive brain areas for 6 or 12 h. At each time point, food intake and different markers of energy homeostasis were analyzed to reveal the consequences of cerebral increase in ketone body level detection. First, an increase in food intake appeared over a 12-h period of brain ketone body perfusion. This stimulated food intake was associated with an increased expression of the hypothalamic neuropeptides NPY and AgRP as well as phosphorylated AMPK and is due to ketone bodies sensed by the brain, as blood ketone body levels did not change at that time. In parallel, gluconeogenesis and insulin sensitivity were transiently altered. Indeed, a dysregulation of glucose production and insulin secretion was observed after 6 h of ketone body perfusion, which reversed to normal at 12 h of perfusion. Altogether, these results suggest that an increase in brain ketone body concentration leads to hyperphagia and a transient perturbation of peripheral metabolic homeostasis.

MetaNetX/MNXref - reconciliation of metabolites and biochemical reactions to bring together genome-scale metabolic networks.

MetaNetX is a repository of genome-scale metabolic networks (GSMNs) and biochemical pathways from a number of major resources imported into a common namespace of chemical compounds, reactions, cellular compartments-namely MNXref-and proteins. The MetaNetX.org website (http://www.metanetx.org/) provides access to these integrated data as well as a variety of tools that allow users to import their own GSMNs, map them to the MNXref reconciliation, and manipulate, compare, analyze, simulate (using flux balance analysis) and export the resulting GSMNs. MNXref and MetaNetX are regularly updated and freely available.

Constrained Total Energy Expenditure and Metabolic Adaptation to Physical Activity in Adult Humans.

Current obesity prevention strategies recommend increasing daily physical activity, assuming that increased activity will lead to corresponding increases in total energy expenditure and prevent or reverse energy imbalance and weight gain [1-3]. Such Additive total energy expenditure models are supported by exercise intervention and accelerometry studies reporting positive correlations between physical activity and total energy expenditure [4] but are challenged by ecological studies in humans and other species showing that more active populations do not have higher total energy expenditure [5-8]. Here we tested a Constrained total energy expenditure model, in which total energy expenditure increases with physical activity at low activity levels but plateaus at higher activity levels as the body adapts to maintain total energy expenditure within a narrow range. We compared total energy expenditure, measured using doubly labeled water, against physical activity, measured using accelerometry, for a large (n = 332) sample of adults living in five populations [9]. After adjusting for body size and composition, total energy expenditure was positively correlated with physical activity, but the relationship was markedly stronger over the lower range of physical activity. For subjects in the upper range of physical activity, total energy expenditure plateaued, supporting a Constrained total energy expenditure model. Body fat percentage and activity intensity appear to modulate the metabolic response to physical activity. Models of energy balance employed in public health [1-3] should be revised to better reflect the constrained nature of total energy expenditure and the complex effects of physical activity on metabolic physiology.

Fast and sensitive supercritical fluid chromatography - tandem mass spectrometry multi-class screening method for the determination of doping agents in urine.

This study shows the possibility offered by modern ultra-high performance supercritical fluid chromatography combined with tandem mass spectrometry in doping control analysis. A high throughput screening method was developed for 100 substances belonging to the challenging classes of anabolic agents, hormones and metabolic modulators, synthetic cannabinoids and glucocorticoids, which should be detected at low concentrations in urine. To selectively extract these doping agents from urine, a supported liquid extraction procedure was implemented in a 48-well plate format. At the tested concentration levels ranging from 0.5 to 5 ng/mL, the recoveries were better than 70% for 48-68% of the compounds and higher than 50% for 83-87% of the tested substances. Due to the numerous interferences related to isomers of steroids and ions produced by the loss of water in the electrospray source, the choice of SFC separation conditions was very challenging. After careful optimization, a Diol stationary phase was employed. The total analysis time for the screening assay was only 8 min, and interferences as well as susceptibility to matrix effect (ME) were minimized. With the developed method, about 70% of the compounds had relative ME within the range ±20%, at a concentration of 1 and 5 ng/mL. Finally, limits of detection achieved with the above-described strategy including 5-fold preconcentration were below 0.1 ng/mL for the majority of the tested compounds. Therefore, LODs were systematically better than the minimum required performance levels established by the World anti-doping agency, except for very few metabolites.

[(18)F]FDG-PET/CT metabolic parameters as useful prognostic factors in cervical cancer patients treated with chemo-radiotherapy.

BACKGROUND: To compare the prognostic value of different anatomical and functional metabolic parameters determined using [(18)F]FDG-PET/CT with other clinical and pathological prognostic parameters in cervical cancer (CC). METHODS: Thirty-eight patients treated with standard curative doses of chemo-radiotherapy (CRT) underwent pre- and post-therapy [(18)F]FDG-PET/CT. [(18)F]FDG-PET/CT parameters including mean tumor standardized uptake values (SUV), metabolic tumor volume (MTV) and tumor glycolytic volume (TGV) were measured before the start of CRT. The post-treatment tumor metabolic response was evaluated. These parameters were compared to other clinical prognostic factors. Survival curves were estimated by using the Kaplan-Meier method. Cox regression analysis was performed to determine the independent contribution of each prognostic factor. RESULTS: After 37 months of median follow-up (range, 12-106), overall survival (OS) was 71 % [95 % confidence interval (CI), 54-88], disease-free survival (DFS) 61 % [95 % CI, 44-78] and loco-regional control (LRC) 76 % [95 % CI, 62-90]. In univariate analyses the [(18)F]FDG-PET/CT parameters unfavorably influencing OS, DFS and LRC were pre-treatment TGV-cutoff ≥562 (37 vs. 76 %, p = 0.01; 33 vs. 70 %, p = 0.002; and 55 vs. 83 %, p = 0.005, respectively), mean pre-treatment tumor SUV cutoff ≥5 (57 vs. 86 %, p = 0.03; 36 vs. 88 %, p = 0.004; 65 vs. 88 %, p = 0.04, respectively) and a partial tumor metabolic response after treatment (9 vs. 29 %, p = 0.0008; 0 vs. 83 %, p < 0.0001; 22 vs. 96 %, p < 0.0001, respectively). After multivariate analyses a partial tumor metabolic response after treatment remained as an independent prognostic factor unfavorably influencing DFS and LRC (RR 1:7.7, p < 0.0001, and RR 1:22.6, p = 0.0003, respectively) while the pre-treatment TGV-cutoff ≥562 negatively influenced OS and DFS (RR 1:2, p = 0.03, and RR 1:2.75, p = 0.05). CONCLUSIONS: Parameters capturing the pre-treatment glycolytic volume and metabolic activity of [(18)F]FDG-positive disease provide important prognostic information in patients with CC treated with CRT. The post-therapy [(18)F]FDG-PET/CT uptake (partial tumor metabolic response) is predictive of disease outcome.

Prognostic value of baseline total metabolic tumor volume (TMTV0) measured on FDG-PET/CT in patients with peripheral T-cell lymphoma (PTCL).

BACKGROUND: Most peripheral T-cell lymphoma (PTCL) patients have a poor outcome and the identification of prognostic factors at diagnosis is needed. PATIENTS AND METHODS: The prognostic impact of total metabolic tumor volume (TMTV0), measured on baseline [(18)F]2-fluoro-2-deoxy-d-glucose positron emission tomography/computed tomography, was evaluated in a retrospective study including 108 PTCL patients (27 PTCL not otherwise specified, 43 angioimmunoblastic T-cell lymphomas and 38 anaplastic large-cell lymphomas). All received anthracycline-based chemotherapy. TMTV0 was computed with the 41% maximum standardized uptake value threshold method and an optimal cut-off point for binary outcomes was determined and compared with others prognostic factors. RESULTS: With a median follow-up of 23 months, 2-year progression-free survival (PFS) was 49% and 2-year overall survival (OS) was 67%. High TMTV0 was significantly associated with a worse prognosis. At 2 years, PFS was 26% in patients with a high TMTV0 (>230 cm(3), n = 53) versus 71% for those with a low TMTV0, [P < 0.0001, hazard ratio (HR) = 4], whereas OS was 50% versus 80%, respectively, (P = 0.0005, HR = 3.1). In multivariate analysis, TMTV0 was the only significant independent parameter for both PFS and OS. TMTV0, combined with PIT, discriminated even better than TMTV0 alone, patients with an adverse outcome (TMTV0 >230 cm(3) and PIT >1, n = 33,) from those with good prognosis (TMTV0 ≤230 cm(3) and PIT ≤1, n = 40): 19% versus 73% 2-year PFS (P < 0.0001) and 43% versus 81% 2-year OS, respectively (P = 0.0002). Thirty-one patients (other TMTV0-PIT combinations) had an intermediate outcome, 50% 2-year PFS and 68% 2-year OS. CONCLUSION: TMTV0 appears as an independent predictor of PTCL outcome. Combined with PIT, it could identify different risk categories at diagnosis and warrants further validation as a prognostic marker.

Profound hyperglycemia in knockout mutant mice identifies novel function for POU4F2/Brn-3b in regulating metabolic processes.

The POU4F2/Brn-3b transcription factor has been identified as a potentially novel regulator of key metabolic processes. Loss of this protein in Brn-3b knockout (KO) mice causes profound hyperglycemia and insulin resistance (IR), normally associated with type 2 diabetes (T2D), whereas Brn-3b is reduced in tissues taken from obese mice fed on high-fat diets (HFD), which also develop hyperglycemia and IR. Furthermore, studies in C2C12 myocytes show that Brn-3b mRNA and proteins are induced by glucose but inhibited by insulin, suggesting that this protein is itself highly regulated in responsive cells. Analysis of differential gene expression in skeletal muscle from Brn-3b KO mice showed changes in genes that are implicated in T2D such as increased glycogen synthase kinase-3β and reduced GLUT4 glucose transporter. The GLUT4 gene promoter contains multiple Brn-3b binding sites and is directly transactivated by this transcription factor in cotransfection assays, whereas chromatin immunoprecipitation assays confirm that Brn-3b binds to this promoter in vivo. In addition, correlation between GLUT4 and Brn-3b in KO tissues or in C2C12 cells strongly supports a close association between Brn-3b levels and GLUT4 expression. Since Brn-3b is regulated by metabolites and insulin, this may provide a mechanism for controlling key genes that are required for normal metabolic processes in insulin-responsive tissues and its loss may contribute to abnormal glucose uptake.

Reciprocal Effects on Neurocognitive and Metabolic Phenotypes in Mouse Models of 16p11.2 Deletion and Duplication Syndromes.

The 16p11.2 600 kb BP4-BP5 deletion and duplication syndromes have been associated with developmental delay; autism spectrum disorders; and reciprocal effects on the body mass index, head circumference and brain volumes. Here, we explored these relationships using novel engineered mouse models carrying a deletion (Del/+) or a duplication (Dup/+) of the Sult1a1-Spn region homologous to the human 16p11.2 BP4-BP5 locus. On a C57BL/6N inbred genetic background, Del/+ mice exhibited reduced weight and impaired adipogenesis, hyperactivity, repetitive behaviors, and recognition memory deficits. In contrast, Dup/+ mice showed largely opposite phenotypes. On a F1 C57BL/6N × C3B hybrid genetic background, we also observed alterations in social interaction in the Del/+ and the Dup/+ animals, with other robust phenotypes affecting recognition memory and weight. To explore the dosage effect of the 16p11.2 genes on metabolism, Del/+ and Dup/+ models were challenged with high fat and high sugar diet, which revealed opposite energy imbalance. Transcriptomic analysis revealed that the majority of the genes located in the Sult1a1-Spn region were sensitive to dosage with a major effect on several pathways associated with neurocognitive and metabolic phenotypes. Whereas the behavioral consequence of the 16p11 region genetic dosage was similar in mice and humans with activity and memory alterations, the metabolic defects were opposite: adult Del/+ mice are lean in comparison to the human obese phenotype and the Dup/+ mice are overweight in comparison to the human underweight phenotype. Together, these data indicate that the dosage imbalance at the 16p11.2 locus perturbs the expression of modifiers outside the CNV that can modulate the penetrance, expressivity and direction of effects in both humans and mice.