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Extremely preterm infants are prone to hyperglycemia which is associated with increased mortality and morbidity. Insulin sensitivity is variable in extreme prematurity, and its monitoring, prevention, and treatment are a significant challenge in the NICU. Frequent changes in fluid composition and volumes, as well as large growth and adaptational nutrient requirements are limited by difficult vascular access and blood sampling and risk of drug incompatibilities. Insulin treatment requires specific access and significantly increases fluid intake and sampling. Clinicians, therefore, often compromise by reducing glucose intake and accepting higher glycemia. We report a case series of 11 extremely low birth weight (ELBW) preterms, born between 23 5/7 and 27 6/7 weeks of gestation, treated for transient hyperglycemia during the first 2 weeks of life by continuous subcutaneous insulin infusion (CSII). Insulin concentration was 10 IU/ml, administered via 13 mm Accu-Chek® Tenderlink catheters and a commercial insulin pump (Accu-Chek® Combo, Roche Diabetes Care). Insulin treatment was initiated when glycemia was > 252 mg/dL (14 mmol/l) in two consecutive blood glucose determinations, except for one case when glycemia was 234 mg/dL (13 mmol/l), despite a previous decrease in glucose infusion rate. The starting dose for the CSII was between 0.01 and 0.08 IU/kg/h. The average duration of the CSII was 5 days (1–16 days). CSII in extreme preterm neonates with hyperglycemia was clinically feasible and practical by sparing IV lines and volume and appeared as more rapidly effective than continuous IV administration. No adverse events like hypoglycemia or skin infection were recorded.

Unrestrained ketogenesis leads to life-threatening ketoacidosis whose incidence is high in patients with diabetes. While insulin therapy reduces ketogenesis this approach is sub-optimal. Here, we report an insulin-independent pathway able to normalize diabetic ketogenesis. By generating insulin deficient male mice lacking or re-expressing Toll-Like Receptor 4 (TLR4) only in liver or hepatocytes, we demonstrate that hepatic TLR4 in non-parenchymal cells mediates the ketogenesis-suppressing action of S100A9. Mechanistically, S100A9 acts extracellularly to activate the mechanistic target of rapamycin complex 1 (mTORC1) in a TLR4-dependent manner. Accordingly, hepatic-restricted but not hepatocyte-restricted loss of Tuberous Sclerosis Complex 1 (TSC1, an mTORC1 inhibitor) corrects insulin-deficiency-induced hyperketonemia. Therapeutically, recombinant S100A9 administration restrains ketogenesis and improves hyperglycemia without causing hypoglycemia in diabetic mice. Also, circulating S100A9 in patients with ketoacidosis is only marginally increased hence unveiling a window of opportunity to pharmacologically augment S100A9 for preventing unrestrained ketogenesis. In summary, our findings reveal the hepatic S100A9-TLR4-mTORC1 axis in non-parenchymal cells as a promising therapeutic target for restraining diabetic ketogenesis.

Background Mutations in the melanocortin-4 receptor (MC4R) represent the most common cause of monogenic obesity. Treatment options are limited but glucagon-like peptide-1 receptor agonists (GLP-1 RA) may be of use to induce weight loss. Methods Exome of the patient was captured using the Agilent SureSelect QXT Human All Exon V5 kit and sequenced on Illumina. Clinical findings and results We report obesity-associated diabetes and cirrhosis in a 13-year girl born from consanguineous parents of Afghan origin. Past medical history revealed mild mental retardation and excessive weight gain since infancy. Linear growth was normal. Her father was obese and no diabetes was found in the family. The girl was initially investigated for hoarseness and found to have pulmonary hypertension, later accepted to be secondary to cirrhosis and portal hypertension. Physical examination revealed obesity (BMI 34.9kg/m2) and acanthosis nigricans. Blood exams showed leucopenia and thrombocytopenia without anemia, compatible with portal hypertension. Chest CT revealed important dilatation of the pulmonary arteries, a nodular liver and splenomegaly. Liver biopsy confirmed cirrhosis. An extensive workup including whole exome sequencing identified a homozygous MC4R variant [NM_005912.2 (MC4R): c.63_64del, p.(Tyr21*)], classified as pathogenic according to the ACMG guidelines. Both parents were heterozygous for this variant. An endocrinological workup showed insulin resistance with a HOMA-IR index of 7.27 and diabetes with peak blood glucose of 11.5mmol/l. HbA1c was 5.1% (32mmol/mol). Thyroid tests, leptin, proinsulin levels (3.5pmol/l, n The mutation being homozygous with a predicted complete loss of function (https://www.mc4r.org.uk/), no treatment with a MC4R agonist was tried. At the age of 15 years (BMI 36.0kg/m2), the patient underwent liver transplantation because of progressive portal hypertension and to halt the progression of pulmonary hypertension. At the age of 16 years (BMI 33.2kg/m2, HbA1c 4.9% (30.0 mmol/mol), HOMA-IR 5.3) a treatment with GLP-1 RA (liraglutide) was started at a dosage of 0.6mg and progressively increased to 3mg, in an attempt to induce weight loss, avoid the accumulation of liver fat and to protect the graft. GLP-1 RA is supposed to exerts its effects on appetite independently of the MC4R pathway. 2 months after liraglutide introduction, no side effects, a weight loss of 4kg and a decrease of appetite were observed (BMI 31.6kg/m2, HbA1c 4.5% (26mmol/mol), HOMA-IR 3.14). Conclusion Obesity-associated MCR4 mutations, in homozygous state, may lead to diabetes, liver cirrhosis and porto-pulmonary hypertension. Treatment options are scarce, but GLP-1 RA seem to have a rapid, positive effect on weight and metabolic control. Would earlier treatment have prevented progression to end-stage-liver disease and need for liver transplantation?

Globally it is estimated that over 1 million children and adolescents have Type 1 diabetes with large variations in incidence between different contexts. Health systems need to provide a variety of elements to ensure appropriate diabetes care, such as service delivery; healthcare workforce; information; medical products and technologies; financing and leadership and governance. Describing these elements between Geneva, Switzerland, a high-income country with high spending on healthcare and a large density of doctors, and low- and middle-income countries this article aims to highlight the global inequality of diabetes care. Type 1 diabetes can serve as a litmus as we move towards the centenary of the discovery of insulin and beyond as there is a need for a global movement to ensure that innovation in the management of diabetes benefits the whole diabetes community and not just a select few.

Identifying gene variants causing monogenic diabetes (MD) increases understanding of disease etiology and allows for implementation of precision therapy to improve metabolic control and quality of life. Here, we aimed to assess the prevalence of MD in youth with diabetes in Lithuania, uncover potential diabetes-related gene variants, and prospectively introduce precision treatment. First, we assessed all pediatric and most young-adult patients with diabetes in Lithuania (n = 1,209) for diabetes-related autoimmune antibodies. We then screened all antibody-negative patients (n = 153) using targeted high-throughput sequencing of >300 potential candidate genes. In this group, 40.7% had MD, with the highest percentage (100%) in infants (diagnosis at ages 0–12 months), followed by those diagnosed at ages >1–18 years (40.3%) and >18–25 years (22.2%). The overall prevalence of MD in youth with diabetes in Lithuania was 3.5% (1.9% for GCK diabetes, 0.7% for HNF1A, 0.2% for HNF4A and ABCC8, 0.3% for KCNJ11, and 0.1% for INS). Furthermore, we identified likely pathogenic variants in 11 additional genes. Microvascular complications were present in 26% of those with MD. Prospective treatment change was successful in >50% of eligible candidates, with C-peptide >252 pmol/L emerging as the best prognostic factor.

Prevention of type 1 diabetes mellitus (T1DM)-related complications is dependent on metabolic control. The recommended glycated hemoglobin (HbA1c) values7.5% (58.5 mmol/mol) are met only by a minority of diabetic children and especially adolescents. The aim of this study was to evaluate the impact of an intervention comprising the use of Webdia, a patient-designed app for smartphones, on metabolic control of T1DM in children.Fifty-five patients with T1DM, 10-18 years of age, were included in this single-center, randomized double-crossover study. We tested an intervention consisting of using Webdia for 3 months with monthly feedback and adaptation of the treatment. Main outcome was modification of HbA1c. Secondary outcomes were the prevalence of hypoglycemia and quality of life (QoL).Of the 55 included patients, 33 completed the study, 9 dropped out, and 13 were excluded due to insufficient use of the app. The app was well accepted by the users who completed the study (46.4% rated the program as good and 39.3% as excellent). The intervention led to a reduction of HbA1c by 0.33%, compared to the control group in which HbA1c rose by 0.21% (P = 0.048) in patients with HbA1c values8.0% (63.9 mmol/mol) at inclusion, without increasing the prevalence of hypoglycemia (8.52 ± 9.45 hypoglycemic events during last 2 weeks of intervention vs. 7.62 ± 6.37 observation, P = 0.680). QoL scores were not modified.The intervention resulted in a significant decrease in HbA1c, without increasing the prevalence of hypoglycemia in patients with initial HbA1c8.0% (63.9 mmol/mol).

The study aimed to assess accuracy, satisfaction and usability of a flash glucose monitoring system (FGM) in children and adolescents with type 1 diabetes mellitus (T1DM) attending a diabetes summer camp.Sixty-six children and adolescents with T1DM aged 6 to 17 years participating in a 7-day medically supervised summer camp were enrolled. Capillary blood glucose (BG) and flash glucose (FG) values were measured simultaneously at breakfast, lunch, and dinner and for any given FG value72 mg/dL (4.0 mmol/L) during daytime,108 mg/dL (6.0 mmol/L) at nighttime,270 mg/dL (15.0 mmol/L) or when patient symptoms were discordant with sensor readings. Sensor-related issues were documented and patients' and healthcare professionals' (HCPs) satisfaction was evaluated.FGM demonstrated satisfactory clinical accuracy compared to reference capillary BG values with 98.8% of values falling within the clinically acceptable zones (A and B) of the consensus error grid. Overall mean absolute relative difference (MARD) was 16.7% ± 16.1%. Specific calculations of mean absolute difference (MAD), mean relative difference (MRD), and mean difference (MD) demonstrated that FGM overestimated BG values across all glycemic ranges. Overall satisfaction with the FGM was high in 91.7% participants and 95.0% HCPs, although confidence in the system was low in 18.0% participants and 40.0% HCPs.The FGM exhibited satisfactory clinical accuracy. However, based on the present data, we conclude that no decision should be taken on the basis of a single, non-verified, FGM value alone. Our study highlights the need for revised therapeutic education for patients/families and further investigation on the integration of sensor readings in clinical decision-making.

Background: Cystic fibrosis-related diabetes (CFRD) is the most frequent extrapulmonary complication of cystic fibrosis (CF). Methods: We report the first combined pancreatic islet-lung-liver transplantation in a 14-year-old adolescent. CFTR was analyzed by Sanger sequencing. Further genes were analyzed by high-throughput sequencing. Results: The patient was diagnosed with CF at the age of 14 months. Nine years later, after diagnosis of CFRD, the patient’s BMI and lung function began to decline. Bilateral lung transplantation with simultaneous liver transplantation was performed at the age of 14.5 years. The first islet transplantation (IT) was carried out 10 days later. Six months later, C-peptide secretion after arginine stimulation showed peak values of 371 pmol/L (vs. 569 pmol/L before IT) and insulin doses had slightly increased (1.40 vs. 1.11 units/kg/day before IT). A second IT was performed at the age of 15 years, a third at 16 years. Two years after the first IT, arginine-stimulated C-peptide secretion increased to 2,956 pmol/L and insulin doses could be reduced to 0.82 units/kg/day. HbA1c decreased from 7.3% (57.4 mmol/mol) to 5.9% (41.0 mmol/mol). Conclusion: IT following lung and liver transplantation, with injection of islets into a transplanted organ, is feasible. It improves C-peptide secretion, decreases insulin needs, and lowers HbA1c.

Cell-to-cell communication mediated by gap junctions made of Connexin36 (Cx36) contributes to pancreatic β-cell function. We have recently demonstrated that Cx36 also supports β-cell survival by a still unclear mechanism. Using specific Cx36 siRNAs or adenoviral vectors, we now show that Cx36 downregulation promotes apoptosis in INS-1E cells exposed to the pro-inflammatory cytokines (IL-1β, TNF-α and IFN-γ) involved at the onset of type 1 diabetes, whereas Cx36 overexpression protects against this effect. Cx36 overexpression also protects INS-1E cells against endoplasmic reticulum (ER) stress-mediated apoptosis, and alleviates the cytokine-induced production of reactive oxygen species, the depletion of the ER Ca(2+) stores, the CHOP overexpression and the degradation of the anti-apoptotic protein Bcl-2 and Mcl-1. We further show that cytokines activate the AMP-dependent protein kinase (AMPK) in a NO-dependent and ER-stress-dependent manner and that AMPK inhibits Cx36 expression. Altogether, the data suggest that Cx36 is involved in Ca(2+) homeostasis within the ER and that Cx36 expression is downregulated following ER stress and subsequent AMPK activation. As a result, cytokine-induced Cx36 downregulation elicits a positive feedback loop that amplifies ER stress and AMPK activation, leading to further Cx36 downregulation. The data reveal that Cx36 plays a central role in the oxidative stress and ER stress induced by cytokines and the subsequent regulation of AMPK activity, which in turn controls Cx36 expression and mitochondria-dependent apoptosis of insulin-producing cells.

Background: SRY, located on the Y chromosome, is one of the key genes involved in human sex determination. SRY mutations are responsible for 10–15% of all cases of 46,XY gonadal dysgenesis (GD) but are rarely implicated in the pathogenesis of mixed GD. Methods: SRY was analyzed by sequence analysis of DNA extracted from blood leukocytes. SRY activity was evaluated by SOX9 immunostaining, one of the targets of SRY. Results: We report a case of mixed GD due to a novel SRY point mutation in a patient with a 46,XY karyotype, without mosaicism or submicroscopic genomic imbalances. Hormonal studies showed low anti-müllerian hormone and histological examination of the gonads showed a streak gonad on the right side and a left dysgenetic testis, thus permitting the diagnosis of mixed GD. Immunostaining for SOX9, a target of SRY, was positive in nuclei of Sertoli and epididymal cells in the left gonad and negative on the right, thus indicating asymmetric activation of SRY. Conclusion: Mixed GD can result from SRY mutations without mosaicism, neither in peripheral blood, nor within the gonads. The asymmetric effect of the point mutation implies the presence of local factors modulating SRY expression or action.

Type 1 diabetes develops when most insulin-producing β cells of the pancreas are killed by an autoimmune attack. The in vivo conditions modulating the sensitivity and resistance of β cells to this attack remain largely obscure. Here, we show that connexin 36 (Cx36), a trans-membrane protein that forms gap junctions between β cells in the pancreatic islets, protects mouse β cells against both cytotoxic drugs and cytokines that prevail in the islet environment at the onset of type 1 diabetes. We documented that this protection was at least partially dependent on intercellular communication, which Cx36 and other types of connexin channels establish within pancreatic islets. We further found that proinflammatory cytokines decreased expression of Cx36 and that experimental reduction or augmentation of Cx36 levels increased or decreased β cell apoptosis, respectively. Thus, we conclude that Cx36 is central to β cell protection from toxic insults.

Diabetes develops when the insulin needs of peripheral cells exceed the availability or action of the hormone. This situation results from the death of most beta-cells in type 1 diabetes, and from an inability of the beta-cell mass to adapt to increasing insulin needs in type 2 and gestational diabetes. We analyzed several lines of transgenic mice and showed that connexins (Cxs), the transmembrane proteins that form gap junctions, are implicated in the modulation of the beta-cell mass. Specifically, we found that the native Cx36 does not alter islet size or insulin content, whereas the Cx43 isoform increases both parameters, and Cx32 has a similar effect only when combined with GH. These findings open interesting perspectives for the in vitro and in vivo regulation of the beta-cell mass.

Type 1 diabetes (T1DM) results from destruction of most insulin-secreting pancreatic β-cells. The persistence of β-cells decades after the onset of the disease indicates that the resistance of individual cells to the autoimmune insult is heterogeneous and might depend on the metabolic status of a cell at a given moment. The aim of this study is to investigate whether activation of nicotinic acetylcholine receptors (nACh-Rs) could increase β-cell resistance against the adverse environment prevailing at the onset of T1DM. Here, we show that nACh-R activation by nicotine and choline, 2 agonists of the receptor, decreases murine and human β-cell apoptosis induced by proinflammatory cytokines known to be present in the islet environment at the onset of T1DM. The protective mechanism activated by nicotine and choline involves attenuation of mitochondrial outer membrane permeabilization via modulation of endoplasmic reticulum stress, of the activity of B-cell lymphoma 2 family proteins and cytoplasmic calcium levels. Local inflammation and endoplasmic reticulum stress being key determinants of β-cell death in T1DM, we conclude that pharmacological activation of nACh-R could represent a valuable therapeutic option in the modulation of β-cell death in T1DM.

Diabetic striatopathy is a well-known complication of diabetes in adults. To our knowledge, only 2 cases have been reported in children. We here report the case of a teenager in whom diabetic striatopathy was revealed by the subacute appearance of hemichorea–hemiballism in the context of weight loss, polyuria, and polydipsia. Glycemia control allowed rapid clinical recovery despite established striatal lesions documented on MRI. We also discuss current hypotheses about pathophysiological processes underlying this entity.

Most cell types are functionally coupled by connexin (Cx) channels, i.e. exchange cytoplasmic ions and small metabolites through gap junction domains of their membrane. This form of direct cell-to-cell communication occurs in all existing animals, whatever their position in the phylogenetic scale, and up to humans. Pancreatic beta-cells are no exception, and normally cross-talk with their neighbors via channels made of Cx36. These exchanges importantly contribute to coordinate and synchronize the function of individual cells within pancreatic islets, particularly in the context of glucose-induced insulin secretion. Compelling evidence now indicates that Cx36-mediated coupling, and/or the Cx36 protein per se, play significant regulatory roles in various beta-cell functions, ranging from the biosynthesis, storage and release of insulin. Recent preliminary data further suggest that the protein may also be implicated in the balance of beta-cell growth versus necrosis and apoptosis, and in the regulated expression of specific genes. Here, we review this evidence, discuss the possible involvement of Cx36 in the pathophysiology of diabetes, and evaluate the relevance of this connexin in the therapeutic approaches to the disease.

Background: Transient and permanent neonatal diabetes mellitus (NDM), usually defined as diabetes diagnosed within the first 6 months of life, are rare conditions occurring in 1:90,000-260,000 live births. The origin of NDM is rarely related to type 1 diabetes, but rather to single gene defects. Methods: Genetic analysis was performed using targeted parallel sequencing including 323 diabetes genes. Data were filtered by a locally developed program. Results: A very low birth weight neonate born at 28 weeks postmenstrual age developed diabetes 13 days after birth. The patient was treated with continuous subcutaneous insulin infusion. After 1 month, insulin treatment could be stopped. At 18 months of age, the child was normoglycemic and developing normally. Genetic analysis revealed a novel variant (p.Pro190Leu) in HNF4A, which is located in the ligand binding domain of the transcription factor, and the p.Glu23Lys variant in KCNJ11, which is associated with type 2 diabetes. Conclusion: Here, we describe a novel HNF4A variant associated with transient NDM in a premature infant. We hypothesize that the neonatal phenotype previously described in carriers of HNF4A mutations was modified by the additional variant in KCNJ11 and prematurity.

Aim ATP-sensitive potassium channels are important regulators of insulin secretion. They consist of four sulphonylurea receptor (encoded by ABCC8 ) and four inwardly rectifying protein (encoded by KCNJ11 ) subunits. Activating ABCC8 mutations lead to decreased insulin secretion and to diabetes. Wide phenotype variability is associated with single ABCC8 mutations, ranging from transient or permanent neonatal diabetes (ND) with or without developmental delay (DEND syndrome) to very mild phenotypes. This report describes the case of a Caucasian infant diagnosed with ND at the age of 2months due to a novel ABCC8 missense mutation. Methods ABCC8 was analyzed by sequence analysis. The mutation was present in the patient and her family and was found to be associated with phenotypes ranging from ND to asymptomatic impaired fasting glucose (IFG). Results A novel His863Tyr ABCC8 mutation was identified in a 2-month-old girl diagnosed with ND. After an initial insulin treatment, treatment with glibenclamide was initiated and the treatment with insulin discontinued. The same mutation was found in her father, who had been fortuitously diagnosed with diabetes and had an HbA 1c level of 9% (74.8mmol/mol). The patient's brother and mother both had normal fasting glucose, and were not found to be carriers of the mutation. However, the same mutation was found in her grandmother, who had been asymptomatic and discovered IFG (6.9mmol/L) with an HbA 1c of 6.8% (50.8mmol/mol). Conclusion This case describes a novel ABCC8 mutation and offers a further illustration of the highly variable phenotypes associated with an identical mutation present across three generations.

Fetal adverse environment, such as insufficient maternal nutrition, placental insufficiency and stress, alters organ development and leads to poor fetal growth, also called intrauterine growth retardation (IUGR). IUGR is associated with an increased risk of perinatal mortality and morbidity as well as late-onset metabolic diseases, such as obesity, diabetes and hypertension in adulthood. In the rodent model, IUGR can be induced by fetal caloric restriction, fetal protein restriction, by exposure to high levels of glucocorticoids or by restricted placental blood supply. Such experimental IUGR models show a decreased beta cell mass and lower pancreatic insulin content. Recent research has provided an insight into the mechanisms responsible for the loss of beta cells. Here we review models that give further details about the molecular determinants of fetal and postnatal pancreatic islet development that are required to understand the consequences of fetal insults.

About 30 years ago, pancreatic beta cells were shown to be connected by gap junctions and to exhibit glucose-induced oscillatory electrical activity, two features that were hypothetically linked to insulin secretion. Since then, gap junctions have been shown to be an obligatory feature of beta cells in all species and all physiological conditions studied. They are composed of connexin proteins and allow for beta-cell to beta-cell exchanges of current-carrying ions and other small cytosolic metabolites which synchronize the electrical and metabolic activity of beta cells, and recruit these cells for insulin biosynthesis and release. Together, these effects account for the significant contribution of gap junction-dependent signaling to the control of insulin secretion. More recent data suggest that gap junctions, either via the expression of connexin proteins and/or of the intercellular communications that these proteins permit, also significantly influence beta-cell growth, apoptosis, and the resistance of islets to immune attack. The mechanism(s) whereby gap junction signaling exerts these multiple effects is still obscure. Understanding this mechanism is relevant both to our understanding of the physiology of pancreatic islets and to the pathophysiology of beta-cell dysfunction in both type 1 and type 2 diabetes. Furthermore, appropriate expression of gap junctions may be a prerequisite for the engineering of surrogate insulin-producing cells and their proper three-dimensional packaging, which may be important for using these cells as a cell-based therapy for the treatment of diabetic patients. Here, we review the current status of our knowledge in this field and its exciting perspectives.

The emergence of pancreatic islets has necessitated the development of a signalling system for the intra- and inter-islet coordination of beta cells. With evolution, this system has evolved into a complex regulatory network of partially cross-talking pathways, whereby individual cells sense the state of activity of their neighbours and, accordingly, regulate their own level of functioning. A consistent feature of this network in vertebrates is the expression of connexin (Cx)-36-made cell-to-cell channels, which cluster at gap junction domains of the cell membrane, and which adjacent beta cells use to share cytoplasmic ions and small metabolites within individual islets. This chapter reviews what is known about Cx36, and the mechanism whereby this beta-cell connexin significantly regulates insulin secretion. It further outlines other less established functions of the protein and evaluates its potential relevance for the development of novel therapeutic approaches to diabetes.

The emergence of multicellular organisms has necessitated the specialization of short- and long-range chemical signaling systems, including that provided by the endocrine system. Conversely, the existence of an endocrine system conceptually demands a multicellular organism, to which proper signaling usually also imposes a multicellular gland. Accordingly, the secretory cells of all endocrine glands have developed mechanisms for interacting with adjacent and distant cells. With evolution, such mechanisms have diversified and have been progressively integrated in a complex regulatory network, whereby individual endocrine cells sense the state of activity of their neighbors and regulate accordingly their own level of functioning. A consistent feature of this network is the expression of connexin-made channels between the hormone-producing cells of all glands so far investigated in vertebrates. In a few instances, these channels have also been documented between the endocrine cells and nearby target cells. Here, we have reviewed the distribution of connexins in the mammalian endocrine system, and have discussed the recent evidence pointing to the participation of these proteins in the functioning of endocrine cells, and on the action of hormones on specific target cells.

Glands were the first type of tissues in which the permissive role of gap junctions in the cell-to-cell transfer of membrane-impermeant molecules was shown. During the 40 years that have followed this seminal finding, gap junctions have been documented in all types of multicellular secretory systems, whether of the exocrine, endocrine or pheromonal nature. Also, compelling evidence now indicates that gap junction-mediated coupling, and/or the connexin proteins per se, play significant regulatory roles in various aspects of gland functions, ranging from the biosynthesis, storage and release of a variety of secretory products, to the control of the growth and differentiation of secretory cells, and to the regulation of gland morphogenesis. This review summarizes this evidence in the light of recent reports.

Introduction Le diabete de type 1 resulte d'une destruction auto-immune de la majorite des cellules beta pancreatiques. Nous avons teste si les connexines (Cxs), des proteines transmembranaires permettant le couplage intercellulaire via les jonctions gap, etaient impliquees dans la modulation de l'apoptose des cellules beta exposees a divers toxines in vivo et in vitro mimant l'environnement cellulaire en debut de diabete de type 1. Materiels et methodes Des souris RIP-Cx36 (qui surexpriment la Cx36 native), RIP-Cx43 et RIP-Cx32 (qui expriment les Cxs 43 ou 32 en plus de la Cx36) et KO-Cx36 (invalidees pour la Cx36) ont ete injectees avec 200mg/kg de streptozotocine (STZ) ou 70mg/kg d'alloxane (AX). Des ilots isoles de ces souris ont ete exposes in vitro a 4,4mm de STZ ou a un cocktail de 0,25ng/ml d'IL-1 beta + 0,1μg/ml d'IFN gamma + 9,1ng/ml de TNF alpha. Le couplage intercellulaire a ete quantifie par micro-injection de jaune de lucifer ou de bromure d'ethidium. Resultats L'injection de STZ ou d'AX a des souris controles presentant un niveau de couplage normal a immediatement resulte en une hyperglycemie. Les souris presentant un couplage intercellulaire augmente (les souris heterozygotes ou homozygotes des lignees RIP-Cx36, RIP-Cx32 et RIP-Cx43) sont restees normoglycemiques. Les souris presentant un couplage diminue ou aboli (les souris heterozygotes ou homozygotes de la lignee KO-Cx36) sont devenues plus diabetiques que les controles. L'exposition in vitro d'ilots isoles des souris RIP-Cx36 et KO-Cx36 a la STZ ou aux cytokines a montre que l'apoptose des cellules beta etait inversement proportionnelle aux niveaux de Cx36 et de couplage. Conclusion La resistance de cellules beta a la STZ, l'AX ou aux cytokines diabetogenes est proportionnelle au couplage intercellulaire confere par les connexines. Des strategies visant a augmenter pharmacologiquement le couplage intercellulaire pourraient representer une nouvelle option therapeutique.

The advent of multicellular organisms was accompanied by the development of short- and long-range chemical signalling systems, including those provided by the nervous and endocrine systems. In turn, the cells of these two systems have developed mechanisms for interacting with both adjacent and distant cells. With evolution, such mechanisms have diversified to become integrated in a complex regulatory network, whereby individual endocrine and neuro-endocrine cells sense the state of activity of their neighbors and, accordingly, regulate their own level of functioning. A consistent feature of this network is the expression of connexin-made channels between the (neuro)hormone-producing cells of all endocrine glands and secretory regions of the central nervous system so far investigated in vertebrates. This review summarizes the distribution of connexins in the mammalian (neuro)endocrine systems, and what we know about the participation of these proteins on hormone secretion, the life of the producing cells, and the action of (neuro)hormones on specific targets. The data gathered since the last reviews on the topic are summarized, with particular emphasis on the roles of Cx36 in the function of the insulin-producing beta cells of the endocrine pancreas, and of Cx40 in that of the renin-producing juxta-glomerular epithelioid cells of the kidney cortex. This article is part of a Special Issue entitled: The Communicating junctions, composition, structure and characteristics.

Poor fetal growth, also known as intrauterine growth restriction (IUGR), is a worldwide health concern. IUGR is commonly associated with both an increased risk in perinatal mortality and a higher prevalence of developing chronic metabolic diseases later in life. Obesity, type 2 diabetes or metabolic syndrome could result from noxious "metabolic programming." In order to better understand early alterations involved in metabolic programming, we modeled IUGR rat pups through either prenatal exposure to synthetic glucocorticoid (dams infused with dexamethasone 100 µg/kg/day, DEX) or prenatal undernutrition (dams feeding restricted to 30% of ad libitum intake, UN). Physiological (glucose and insulin tolerance), morphometric (automated tissue image analysis) and transcriptomic (quantitative PCR) approaches were combined during early life of these IUGR pups with a special focus on their endocrine pancreas and adipose tissue development. In the absence of catch-up growth before weaning, DEX and UN IUGR pups both presented basal hyperglycaemia, decreased glucose tolerance, and pancreatic islet atrophy. Other early metabolic defects were model-specific: DEX pups presented decreased insulin sensitivity whereas UN pups exhibited lowered glucose-induced insulin secretion and more marked alterations in gene expression of pancreatic islet and adipose tissue development regulators. In conclusion, these results show that before any catch-up growth, IUGR rats present early physiologic, morphologic and transcriptomic defects, which can be considered as initial mechanistic basis of metabolic programming.