Insulin Biosynthesis Research Articles

Transcriptome analysis to identify candidate genes related to mammary gland development of Bactrian camel (Camelus bactrianus).

The demand for camel milk, which has unique therapeutic properties, is increasing. The mammary gland is the organ in mammals responsible for the production and quality of milk. However, few studies have investigated the genes or pathways related to mammary gland growth and development in Bactrian camels. This study aimed to compare the morphological changes in mammary gland tissue and transcriptome expression profiles between young and adult female Bactrian camels and to explore the potential candidate genes and signaling pathways related to mammary gland development. Three 2 years-old female camels and three 5 years-old adult female camels were maintained in the same environment. The parenchyma of the mammary gland tissue was sampled from the camels using percutaneous needle biopsy. Morphological changes were observed using hematoxylin-eosin staining. High-throughput RNA sequencing was performed using the Illumina HiSeq platform to analyze changes in the transcriptome between young and adult camels. Functional enrichment, pathway enrichment, and protein-protein interaction networks were also analyzed. Gene expression was verified using quantitative real-time polymerase chain reaction (qRT-PCR). Histomorphological analysis showed that the mammary ducts and mammary epithelial cells in adult female camels were greatly developed and differentiated from those in young camels. Transcriptome analysis showed that 2,851 differentially expressed genes were obtained in the adult camel group compared to the young camel group, of which 1,420 were upregulated, 1,431 were downregulated, and 2,419 encoded proteins. Functional enrichment analysis revealed that the upregulated genes were significantly enriched for 24 pathways, including the Hedgehog signaling pathway which is closely related to mammary gland development. The downregulated genes were significantly enriched for seven pathways, among these the Wnt signaling pathway was significantly related to mammary gland development. The protein-protein interaction network sorted the nodes according to the degree of gene interaction and identified nine candidate genes: PRKAB2, PRKAG3, PLCB4, BTRC, GLI1, WIF1, DKK2, FZD3, and WNT4. The expression of fifteen genes randomly detected by qRT-PCR showed results consistent with those of the transcriptome analysis. Preliminary findings indicate that the Hedgehog, Wnt, oxytocin, insulin, and steroid biosynthesis signaling pathways have important effects on mammary gland development in dairy camels. Given the importance of these pathways and the interconnections of the involved genes, the genes in these pathways should be considered potential candidate genes. This study provides a theoretical basis for elucidating the molecular mechanisms associated with mammary gland development and milk production in Bactrian camels.

Liposome-Encapsulated Berberine Alleviates Liver Injury in Type 2 Diabetes via Promoting AMPK/mTOR-Mediated Autophagy and Reducing ER Stress: Morphometric and Immunohistochemical Scoring.

In the advanced stages of type 2 diabetes mellitus (T2DM), diabetic liver damage is a common complication that can devastate a patient's quality of life. The present study investigated the ability of liposomal berberine (Lip-BBR) to aid in ameliorating hepatic damage and steatosis, insulin homeostasis, and regulating lipid metabolism in type 2 diabetes (T2DM) and the possible pathways by which it does so. Liver tissue microarchitectures and immunohistochemical staining were applied during the study. The rats were divided into a control non-diabetic group and four diabetic groups, which are the T2DM, T2DM-Lip-BBR (10 mg/kg b.wt), T2DM-Vildagliptin (Vild) (10 mg/kg b.wt), and T2DM-BBR-Vild (10 mg/kg b.wt + Vild (5 mg/kg b.wt) groups. The findings demonstrated that Lip-BBR treatment could restore liver tissue microarchitectures, reduce steatosis and liver function, and regulate lipid metabolism. Moreover, Lip-BBR treatment promoted autophagy via the activation of LC3-II and Bclin-1 proteins and activated the AMPK/mTOR pathway in the liver tissue of T2DM rats. Lip-BBR also activated the GLP-1 expression, which stimulated insulin biosynthesis. It decreased the endoplasmic reticulum stress by limiting the CHOP, JNK expression, oxidative stress, and inflammation. Collectively, Lip-BBR ameliorated diabetic liver injury in a T2DM rat model with its promotion activity of AMPK/mTOR-mediated autophagy and limiting ER stress.

Nutrient-dependent regulation of β-cell proinsulin content

Insulin is made from proinsulin, but the extent to which fasting/feeding controls the homeostatically regulated proinsulin pool in pancreatic β-cells remains largely unknown. Here, we first examined β-cell lines (INS1E and Min6, which proliferate slowly and are routinely fed fresh medium every 2-3days) and found that the proinsulin pool size responds to each feeding within 1 to 2h, affected both by the quantity of fresh nutrients and the frequency with which they are provided. We observed no effect of nutrient feeding on the overall rate of proinsulin turnover as quantified from cycloheximide-chase experiments. We show that nutrient feeding is primarily linked to rapid dephosphorylation of translation initiation factor eIF2α, presaging increased proinsulin levels (and thereafter, insulin levels), followed by its rephosphorylation during the ensuing hours that correspond to a fall in proinsulin levels. The decline of proinsulin levels is blunted by the integrated stress response inhibitor, ISRIB, or by inhibition of eIF2α rephosphorylation with a general control nonderepressible 2 (not PERK) kinase inhibitor. In addition, we demonstrate that amino acids contribute importantly to the proinsulin pool; mass spectrometry shows that β-cells avidly consume extracellular glutamine, serine, and cysteine. Finally, we show that in both rodent and human pancreatic islets, fresh nutrient availability dynamically increases preproinsulin, which can be quantified without pulse-labeling. Thus, the proinsulin available for insulin biosynthesis is rhythmically controlled by fasting/feeding cycles.

Endocrine disruptors in plastics alter β-cell physiology and increase the risk of diabetes mellitus.

Plastic pollution breaks a planetary boundary threatening wildlife and humans through its physical and chemical effects. Of the latter, the release of endocrine disrupting chemicals (EDCs) has consequences on the prevalence of human diseases related to the endocrine system. Bisphenols (BPs) and phthalates are two groups of EDCs commonly found in plastics that migrate into the environment and make low-dose human exposure ubiquitous. Here we review epidemiological, animal, and cellular studies linking exposure to BPs and phthalates to altered glucose regulation, with emphasis on the role of pancreatic β-cells. Epidemiological studies indicate that exposure to BPs and phthalates is associated with diabetes mellitus. Studies in animal models indicate that treatment with doses within the range of human exposure decreases insulin sensitivity and glucose tolerance, induces dyslipidemia, and modifies functional β-cell mass and serum levels of insulin, leptin, and adiponectin. These studies reveal that disruption of β-cell physiology by EDCs plays a key role in impairing glucose homeostasis by altering the mechanisms used by β-cells to adapt to metabolic stress such as chronic nutrient excess. Studies at the cellular level demonstrate that BPs and phthalates modify the same biochemical pathways involved in adaptation to chronic excess fuel. These include changes in insulin biosynthesis and secretion, electrical activity, expression of key genes, and mitochondrial function. The data summarized here indicate that BPs and phthalates are important risk factors for diabetes mellitus and support a global effort to decrease plastic pollution and human exposure to EDCs.

Correlation of epicardial adipocytes hypertrophy with adipokines, inflammation and glucose and lipid metabolism

The changes of epicardial adipose tissue’s (EAT) morphofunctional characteristics represent an important factor of cardiometabolic impairments development. However, factor data determining the severity of EAT adipocytes’ hypertrophy in patients with coronary atherosclerosis are absent in literature.Aim: To compare the size of the EAT adipocyte and the percentage of hypertrophied adipocytes with the parameters of glucose/insulin metabolism, blood lipid transport function, adipokines’ profile and serum levels of high sensitive C-reactive protein (hsCRP) in patients with chronic coronary artery disease (CAD) undergoing coronary artery bypass grafting (CABG); to establish statistically significant determinants of a pronou ced degree of EAT adipocytes’ hypertrophy.Material and Methods. The study included 42 patients (m/f 28/14) aged 53–72 y.o. with CAD, who underwent CABG. The material for the study was EAT adipocytes obtained by the enzymatic method from intraoperative explants. The basal blood levels of glycemia, insulinemia, C-peptide, blood lipid transport function, adipokines and hsCRP were determined. The median indicators of the size of EAT adipocytes and the proportion of EAT adipocytes over 100 μm were 87.32 μm and 14.64%, respectively. The total sample of patients was divided into two groups: gr. 1 with an average size of EAT adipocytes less than or equal to 87.32 μm and gr. 2 with an average size of EAT adipocytes more than 87.32 μm. Gr. 2 had higher body mass index, waist and hip circumferences, triglycerides, hsCRP, and lower adiponectin levels, while the median proportion of hypertrophied adipocytes was three times higher than in group 1. A model of multiple logistic regression was constructed, according to which statistically significant determinants of the pronounced EAT adipocytes’ hypertrophy are represented by the decreased level of adiponectin, and increased concentrations of hsCRP and C-peptide, which reflects the biosynthesis and secretion of insulin. The predictive accuracy of the model was 82%, sensitivity 85%, specificity 79%, AUC = 0.89.Conclusion. Our results indicate a close correlation between the development of EAT adipocytes hypertrophy, impaired production of adiponectin, insulin, and inflammation processes. Concentrations of adiponectin, hsCRP, and basal C-peptide in the blood are biomarkers that accurately determine the presence of EAT adipocyte hypertrophy.

A Review of the Biosynthesis and Structural Implications of Insulin Gene Mutations Linked to Human Disease

The discovery of the insulin hormone over 100 years ago, and its subsequent therapeutic application, marked a key landmark in the history of medicine and medical research. The many roles insulin plays in cell metabolism and growth have been revealed by extensive investigations into the structure and function of insulin, the insulin tyrosine kinase receptor (IR), as well as the signalling cascades, which occur upon insulin binding to the IR. In this review, the insulin gene mutations identified as causing disease and the structural implications of these mutations will be discussed. Over 100 studies were evaluated by one reviewing author, and over 70 insulin gene mutations were identified. Mutations may impair insulin gene transcription and translation, preproinsulin trafficking and proinsulin sorting, or insulin-IR interactions. A better understanding of insulin gene mutations and the resultant pathophysiology can give essential insight into the molecular mechanisms underlying impaired insulin biosynthesis and insulin-IR interaction.

Role of selenium in type 2 diabetes, insulin resistance and insulin secretion.

Selenium is a trace mineral essential for life that acts physiologically through selenoproteins. Among other actions, the endogenous antioxidant selenoprotein glutathione peroxidase and the selenium transporter in blood, selenoprotein P, seem to play an important role in type 2 diabetes mellitus and insulin resistance by weakening the insulin signaling cascade through different mechanisms. Recent findings also suggest that selenoproteins also affect insulin biosynthesis and insulin secretion. This review discussed the role of selenium in type 2 diabetes and the complex interplay between selenoproteins and insulin pathways.

Methylation of histone H3 lysine 4 is required for maintenance of beta cell function in adult mice

Aims/hypothesisBeta cells control glucose homeostasis via regulated production and secretion of insulin. This function arises from a highly specialised gene expression programme that is established during development and then sustained, with limited flexibility, in terminally differentiated cells. Dysregulation of this programme is seen in type 2 diabetes but mechanisms that preserve gene expression or underlie its dysregulation in mature cells are not well resolved. This study investigated whether methylation of histone H3 lysine 4 (H3K4), a marker of gene promoters with unresolved functional importance, is necessary for the maintenance of mature beta cell function.MethodsBeta cell function, gene expression and chromatin modifications were analysed in conditional Dpy30 knockout mice, in which H3K4 methyltransferase activity is impaired, and in a mouse model of diabetes.ResultsH3K4 methylation maintains expression of genes that are important for insulin biosynthesis and glucose responsiveness. Deficient methylation of H3K4 leads to a less active and more repressed epigenome profile that locally correlates with gene expression deficits but does not globally reduce gene expression. Instead, developmentally regulated genes and genes in weakly active or suppressed states particularly rely on H3K4 methylation. We further show that H3K4 trimethylation (H3K4me3) is reorganised in islets from the Leprdb/db mouse model of diabetes in favour of weakly active and disallowed genes at the expense of terminal beta cell markers with broad H3K4me3 peaks.Conclusions/interpretationSustained methylation of H3K4 is critical for the maintenance of beta cell function. Redistribution of H3K4me3 is linked to gene expression changes that are implicated in diabetes pathology.Graphical abstract

Glucose Homeostasis and Pancreatic Islet Size Are Regulated by the Transcription Factors Elk-1 and Egr-1 and the Protein Phosphatase Calcineurin.

Pancreatic β-cells synthesize and secrete insulin. A key feature of diabetes mellitus is the loss of these cells. A decrease in the number of β-cells results in decreased biosynthesis of insulin. Increasing the number of β-cells should restore adequate insulin biosynthesis leading to adequate insulin secretion. Therefore, identifying proteins that regulate the number of β-cells is a high priority in diabetes research. In this review article, we summerize the results of three sophisticated transgenic mouse models showing that the transcription factors Elk-1 and Egr-1 and the Ca2+/calmodulin-regulated protein phosphatase calcineurin control the formation of sufficiently large pancreatic islets. Impairment of the biological activity of Egr-1 and Elk-1 in pancreatic β-cells leads to glucose intolerance and dysregulation of glucose homeostasis, the process that maintains glucose concentration in the blood within a narrow range. Transgenic mice expressing an activated calcineurin mutant also had smaller islets and showed hyperglycemia. Calcineurin induces dephosphorylation of Elk-1 which subsequently impairs Egr-1 biosynthesis and the biological functions of Elk-1 and Egr-1 to regulate islet size and glucose homeostasis.

Diabetes and diabesity in the view of proteomics, drug, and plant-derived remedies.

Diabetes and obesity are highly prevalent in the world. Proteomics is a promising approach to better understanding enzymes, proteins, and signaling molecules involved in diabetes processes which help recognize the basis of the disease better and find suitable new treatments. This study aimed to summarize the molecular mechanisms from the beginning of insulin secretion in response to stimuli to the pathology of the insulin signaling pathway and, finally, the mechanisms of drugs/chemicals remedies that affect this process. The titles and subtitles of this process were determined, and then for each of them, the articles searched in PubMed and ScienceDirect were used. This review article starts the discussion with the molecular basis of insulin biosynthesis, secretion, insulin's mechanism of action, and molecular aspect of diabetes and diabesity (a new term showing the relation between diabetes and obesity) and ends with the drug and plant-derived intervention for hyperglycemia.

PanCircBase: An online resource for the exploration of circular RNAs in pancreatic islets.

Circular RNAs (circRNAs) are a novel class of covalently closed RNA molecules that recently emerged as a critical regulator of gene expression in development and diseases. Recent research has highlighted the importance of novel circRNAs in the biosynthesis and secretion of insulin from β-cells of pancreatic islets. However, all circRNAs expressed in pancreatic islets or β-cells are not readily available in the database. In this study, we analyzed publicly available RNA-sequencing datasets of the pancreatic islets to catalog all circRNAs expressed in pancreatic islets to construct the PanCircBase (https://www.pancircbase.net/) database that provides the following resources: 1) pancreatic islet circRNA annotation details (genomic position, host gene, exon information, splice length, sequence, other database IDs, cross-species conservation), 2) divergent primers for PCR analysis of circRNAs, 3) siRNAs for silencing of target circRNAs, 4) miRNAs associated with circRNAs, 5) possible protein-coding circRNAs and their polypeptides. In summary, this is a comprehensive online resource for exploring circRNA expression and its possible function in pancreatic β-cells.

Glucocorticoids and glucolipotoxicity alter the DNA methylome and function of human EndoC-βH1 cells

AimsSynthetic glucocorticoids, including dexamethasone (DEX), are clinically prescribed due to their immunoregulatory properties. In excess they can perturb glucose homeostasis, with individuals predisposed to glucose intolerance more sensitive to these negative effects. While DEX is known to negatively impact β-cell function, it is unclear how. Hence, our aim was to investigate the effect of DEX on β-cell function, both alone and in combination with a diabetogenic milieu in the form of elevated glucose and palmitate. Main methodsHuman pancreatic EndoC-βH1 cells were cultured in the presence of high glucose and palmitate (glucolipotoxicity) and/or a pharmacological concentration of DEX, before functional and molecular analyses. Key findingsEither treatment alone resulted in reduced insulin content and secretion, while the combination of DEX and glucolipotoxicity promoted a strong synergistic effect. These effects were associated with reduced insulin biosynthesis, likely due to downregulation of PDX1, MAFA, and the proinsulin converting enzymes, as well as reduced ATP response upon glucose stimulation. Genome-wide DNA methylation analysis found changes on PDE4D, MBNL1 and TMEM178B, all implicated in β-cell function, after all three treatments. DEX alone caused very strong demethylation of the glucocorticoid-regulated gene ZBTB16, also known to influence the β-cell, while the combined treatment caused altered methylation of many known β-cell regulators and diabetes candidate genes. SignificanceDEX treatment and glucolipotoxic conditions separately alter the β-cell epigenome and function. The combination of both treatments exacerbates these changes, showing that caution is needed when prescribing potent glucocorticoids in patients with dysregulated metabolism.

An Investigation of Insulinotropic Potential of Herbal Plants for Management of Diabetes

The Insulinotropic hormone glucagon-like peptide-1, which has been proposed as a modern treatment for management of diabetes, is metabolized extremely with the aid of dipeptidyl peptidase-IV. Inhibitors on dipeptidyl peptidase-IV enhance the level of glucagon-like peptide-1, as have elevated glucose tolerance and improved insulin secretion. Recently, incretin-based treatments have end up a beneficial tool to treat diabetic patients, and distinctive research have focused on the identification of glucagon-like peptide-1 receptor agonists, which includes these of herbal origin.
 Aims: This study was aimed to explorations the effect of methanolic extract of plants to inhibit dipeptidyl peptidase-IV and comparing its inhibitory activities with Diprotin, as a reference standard additionally, this study focuses to the influences of glucagon-like peptide-1secretions which accelerated glucose tolerance and provocation of insulin biosynthesis and secretion on STC-1 cell line.
 Study Design: In-vitro model.
 Place and Duration of Study: Department of pharmacology, Karnataka College of pharmacy, Bangalore, India, between Jan 2022 to April 2022.
 Methodology: The test drug undertaking of different medicinal plants extract of management over diabetes right here we were the methanolic extraction of three plants; “Aegle marmelos, Moringa oleifera, then Syzygium cumini” have been tested in-vitro for dipeptidyl peptidase-IV inhibitory activity and have an impact on of incretin system like glucagon-like peptide-1. An in-vitro assay to measure glucagon-like peptide-1release from cultured murine EEC’s under fatty acid stimulation. dipeptidyl peptidase-IV is involved in the inactivation over glucagon-like peptide-1, a potent Insulinotropic peptide.
 Results: The current study underlines up to expectation the extracts inhibits the dipeptidyl peptidase-IV and enhances the glucagon-like peptide-1for diabetes. Results established so the extracts on Aegle marmelos, Moringa oleifera, and Syzygium cumini had dipeptidyl peptidase-IV inhibitory activity on 42.57μg/mL, 42.38/mL, and then 41.48μg/mL respectively. Diprotin A confirmed an IC50 virtue on 29.83μg/mL, as is used as positive controls. Similarly, the study additionally demonstrates that on a cellular level of Aegle marmelos, Syzygium cumini potentially stimulate glucagon-like peptide-1secretion, however Moringa oleifera indicate decent rises into glucagon-like peptide-1secretion.
 Conclusion: The outcomes assure the inhibitory impact about plants regarding dipeptidyl peptidase-IV, glucagon-like peptide-1secretion, and the main in conformity with stand a novel, efficient and fair strategy for the management on diabetes.

Perfluorooctanoic acid promotes pancreatic β cell dysfunction and apoptosis through ER stress and the ATF4/CHOP/TRIB3 pathway.

Perfluorooctanoic acid (PFOA), a widely used chemical substance, causes an increased risk of human type 2 diabetes (T2D), but its underlying mechanism is not well elucidated. The aim of the present study was to investigate whether PFOA regulates the functions of pancreatic β cells, which are specialized for the biosynthesis and secretion of insulin. The treatment of the mouse pancreatic β cell line (MIN6 cells) with PFOA caused a time- and dose-dependent inhibition of cell viability in CCK-8 assays. Annexin V/PI and TUNEL staining results confirmed that exposure to a high PFOA dose (500μM) promoted apoptosis of β cells, while a low dose (300μM) had no effects on β cell survival. PFOA treatment, even at a low dose, diminished glucose-stimulated insulin secretion (GSIS) in both primary islet perfusion and MIN6 cell experiments. RNA-sequencing data showed significantly increased expression of endoplasmic reticulum (ER) stress-associated genes, with tribbles homolog 3 (Trib3) ranking first among the altered genes. The activation of ER stress pathways was verified by qRT-PCR assays, and the ATF4/CHOP/TRIB3 pathway contributed to PFOA-induced β cell damage. The inhibition of TRIB3 expression significantly protected MIN6 cells from PFOA-induced GSIS defects and apoptosis by ameliorating ER stress. These findings reveal a link between ER stress and PFOA-induced β cell defects, opening up a new set of questions about the pathogenesis of T2D due to environmental chemicals.

1375-P: Effects of Irisin Administration on Pancreatic Islets of Diabetic Mice

Irisin is a hormone secreted by skeletal muscle following exercise or excess of saturated fatty acids (SFAs) , able to improve metabolic homeostasis and promote energy expenditure. Serum irisin levels are reduced in type 2 diabetes (T2D) , while exogenous irisin administration improves glycemic control in diabetic mice. We have previously demonstrated that irisin protects human and rodent β-cells and pancreatic islets from SFAs-induced apoptosis, increases insulin biosynthesis and glucose-stimulated insulin secretion (GSIS) , and promotes β-cell proliferation, both in vitro and in vivo in healthy wild-type mice. Irisin may also restore the defective GSIS and reduce the high rate of apoptosis that are characteristic of islets from T2D patients. However, the β-cellular effects of irisin administration to diabetic mice are still unknown. 6 weeks-old C57Bl/6 mice (n = 8) were fed a high-fat diet (HFD, 60% of energy deriving from fat) for weeks and then intraperitoneally injected with streptozotocin (STZ, 100 mg/Kg) to induce diabetes. 4 standard diet (SD) -fed mice were used as control. HFD/STZ mice were then treated with 0.5 μg/g irisin (n = 4) or vehicle (n = 4) for 14 days. Glucose tolerance, glycemia, insulinemia, body weight, pancreatic islet architecture and function were assessed throughout the study. As expected, compared to SD mice, HFD/STZ mice showed higher glycemia and body weight, glucose intolerance, and reduced GSIS; in addition, HFD/STZ mice showed reduced islet volume (-78%) , β-cell area (-35%) , and insulin content (-60%) , while increased α-cell area (+54%) . Irisin administration significantly restored glycemia (-31%) , body weight (-13%) , glucose tolerance (-27%, AUC) , GSIS (+23%, AUC) , islet volume (+61%) , β-cell (+34%) and α-cell (-49%) areas, and insulin content (+36%) . Of note, irisin treatment induced a 9-fold increase in β-cell proliferation rate. These results show for the first time that irisin can restore β-cell functional mass when administered in vivo to diabetic mice. Disclosure N.Marrano: None. G.Biondi: None. A.Borrelli: None. L.Roberto: None. A.Cignarelli: None. S.Perrini: None. L.Laviola: Advisory Panel; Lilly Diabetes, Novo Nordisk, Roche Diabetes Care, Sanofi, Speaker's Bureau; A. Menarini Diagnostics, Abbott Diabetes, Medtronic, Terumo Corporation. F.Giorgino: Advisory Panel; AstraZeneca, Boehringer Ingelheim International GmbH, Novo Nordisk, Consultant; Lilly Diabetes, Sanofi, Research Support; Lilly Diabetes, Roche Diabetes Care, Takeda Pharmaceutical Company Limited. A.Natalicchio: Consultant; Novo Nordisk, Other Relationship; AstraZeneca, Lilly Diabetes, Sanofi. Funding EU – ESF PON R&I 2014-20, AIM

1277-P: Spatial Whole Transcriptome Profiling of the Human Pancreas Uncovers Unique Insights into Histological Structures

Understanding the physiology of the pancreas and pathology that occurs during diabetes requires knowing transcriptional patterns driving biological activity within the functional structures of the tissue. Previous technologies have not enabled spatially resolved high plex profiling to elucidate these biological pathways. Using the unique ability of GeoMx® Digital Spatial Profiler to resolve functional units within FFPE tissue in situ, we provide whole transcriptome expression data from islets, acini, and ducts from four pancreata of nondiabetes patients. On average, 6000-8000 genes were detected from functional groups within each histological structure. Data were validated against the independent Human Protein Atlas, with ∼90% concordance between RNA expression and known protein localization. Deconvolution based on single-cell RNASeq enabled calculation of the proportion of distinct cell types within each structure, confirming cell composition. For example, while ductal components consist of small islands punctuating the acini, over 3000 genes were identified to be highly specific to each structure (FDR < 0.05) , and enriched for pathways related to focal adhesion, ECM structure, and diabetic disease processes. Within islets, we identified >300 genes with differences between α- and β-cells (FDR < 0.2) . Functional characterization confirmed enrichment of insulin biosynthesis and secretion pathways, with genes such as insulin, glucagon, and IAPP expression captured accurately with a single assay. Determination of expression in four individual pancreas samples identified variation between tissues, which may be central to health and disease processes. In conclusion, whole transcriptome data for spatial gene expression profiles of structures of the non-diseased pancreas are publicly available and can be used as standards to inform future profiling studies in normal and diseased tissue. FOR RESEARCH USE ONLY. Not for use in diagnostic procedures. Disclosure W.Yang: None. M.F.Hogan: Employee; NanoString. Y.Liang: None. J.M.Beechem: None.

Autonomous regulation of retinal insulin biosynthesis in diabetes

Diabetic retinopathy (DR) is a neurodegenerative disease that results as a complication of dysregulated glucose metabolism, or diabetes. The signaling of insulin is lost or dampened in diabetes, but this hormone has also been shown to be an important neurotrophic factor which supports neurons of the brain. The role of local insulin synthesis and secretion in the retina, however, is unclear. We have investigated whether changes in local insulin synthesis occur in the diabetic retina and in response to stressors known to initiate retinal neurodegenerative processes. The expression of insulin and its cleavage product, c-peptide, were examined in retinas of a Type I diabetes animal model and human postmortem donors with DR. We detected mRNAs for insulin I (Ins1), insulin II (Ins2) and human insulin (Ins) by quantitative real-time polymerase chain reaction (qRT-PCR) and in situ hybridization. Using an ex-vivo system, isolated neuroretinas and retinal pigmented epithelium (RPE) layers were exposed to glycemic, oxidative and inflammatory environments to measure insulin gene transcripts produced de novo in the retina under disease-relevant conditions. The expression of insulin in the retina was altered with the progression of diabetes in STZ mice and donors with DR. Transcription factors for insulin, were simultaneously expressed in a pattern matching insulin genes. Furthermore, de novo insulin mRNA in isolated retinas was induced by acute stress. RPE explants displayed the most pronounced changes in Ins1 and Ins2. This data reveals that the retina, like the brain, is an organ capable of producing local insulin and this synthesis is altered in diabetes.

Pancreatic Interleukin-22 Receptor Signaling is Critical in Maintaining Beta-Cell Insulin Production and is Hepatoprotective

Abstract We discovered that the cytokine interleukin-22 (IL-22) is an efficient natural inhibitor of cellular stress and exogenous IL-22 improved insulin quality in pancreatic β-cells in preclinical models of Type 2 diabetes. Importantly, IL-22 completely restored glucose tolerance, suppressed fasting hyperinsulinemia/hyperproinsulinemia, and restored insulin sensitivity in obese animals. Moreover, metabolic improvements were accompanied by significant improvements in circulating triglycerides, liver function (AST:ALT ratio) and a reduction in hepatic lipid accumulation. Whilst the IL-22 receptor, IL-22RA1 is highly expressed in the pancreas and liver, its endogenous role in these tissues remains elusive. To explore this, we generated tissue specific IL-22ra1 knockout mice lacking the receptor in pancreatic β-cells (Il-22ra1fl/fl x Ins2Cre: IL-22ra1β-cell−/−) and hepatocytes (Il-22ra1fl/fl x AlbCre: IL-22ra1Hep−/−). We assessed their metabolic phenotype including glycemic control, hepatic lipid accumulation, and hepatic markers of cellular stress, lipid, and glucose metabolism with age or with obesity. We discovered that IL-22ra1β-cell−/− animals developed hyperglycemia with age and had defective insulin secretion, which was exacerbated when on a high fat diet. Interestingly, they also had a significant increase in markers of hepatic inflammation and cellular stress. In conclusion we demonstrate, for the first time, that local endogenous IL-22 secretion in pancreatic β-cells maintains insulin biosynthesis. Moreover, our work highlights the importance of the pancreatic-β-cell-liver axis as the absence of pancreatic IL-22ra1 signaling leads to a marked increase in liver inflammation and cellular stress.

Effects of Zinc Deficiency in Male Mice on Glucose Metabolism of Male Offspring.

As an essential metal, zinc is central to insulin biosynthesis and energy metabolism. Zinc can not only maintain the activity of insulin, but also has insulin-like effect. When zinc is sufficient, the body needs less insulin. Zinc can correct abnormal glucose tolerance and even replace insulin to improve glucose metabolism disorder in diabetic rats. However, the effect of paternal zinc deficiency on glucose metabolism of offspring is still unclear. In the present study, sixteen 8-week-old male mice were randomly allocated into low-zinc group and control group (8 mice in each group), which were fed with low zinc and standard diet for 6 weeks, respectively. The mice were mated with female mice fed with standard diet to get the first generation of mice (F1) to explore the effect zinc deficiency on the glucose metabolism of offspring. Glucose tolerance, insulin sensitivity and insulin secretion in mice were determined by oral glucose tolerance test (OGTT), insulin tolerance test (ITT) and glucose stimulated insulin secretion test (GSIS), respectively. Compared with the control group, the fasting blood glucose levels of F1 generation male mice in the low zinc group increased at 15 and 30 min after glucose injection. The blood glucose of F1 generation male mice in the low zinc group of mice decreased at 60, 90, 120, 180, 240 min after insulin injection. Compared with the control group, serum insulin of F1 generation male mice in the low zinc group decreased at 15 min after glucose injection (all p values <0.05). However F1 female mice in the low zinc group did not show abnormal glucose metabolism. Marginal zinc deficiency in male mice can cause abnormal glucose homeostasis in male offspring, but not in female offspring.

Asprosin modulates testicular functions during ageing in mice

Ageing is a gradual and multi-factorial process with a significant impact on fertility. The mechanism of declined testicular functions with age remains elusive. Asprosin is a novel fasting-induced gluconeogenic adipokine that regulates glucose homeostasis. However, the expression and potential role of asprosin in testicular functions with age are largely unexplored. So, the current study was aimed to examine the variation in asprosin expression in the mice testis and its correlation with OLFR734 receptor, insulin receptor (IR), GLUT-8 and various steroidogenic markers at different stages of postnatal development. The result demonstrated the highest expression of asprosin in reproductively active mice, which decreased significantly in aged mice testis. Asprosin expression declined simultaneously with declining testosterone production, testicular glucose and expression of OLFR734, IR, GLUT-8 and AR in aged mice testis. This suggests that declining asprosin expression with advancing age may be a causative factor for regressive changes in the testis. Further, the present study also evaluated the in vitro effect of asprosin on testicular functions of aged mice testis. The results showed that asprosin treatment improves testicular functions by stimulating the expression of OLFR734, StAR, 3β-HSD,17β-HSD, IR, GLUT-8, MCT-2&4, PCNA, Bcl2 proteins alongwith increased testosterone, insulin and lactate biosynthesis. Collectively, these findings indicate that a marked decline in asprosin and its receptor OLFR734 expression may result in decreased insulin sensitivity and glucose transport, leading to regressive changes in aged mice testis. Treatment of asprosin can possibly restore the testicular functions of aged mice by augmenting the testosterone, insulin and glucose levels.