Project description:To evaluate functional consequences of insulin-deficient diabetes mellitus for the liver, we used a genetically engineered pig model of mutant INS gene induced diabetes of youth (MIDY). Liver samples of MIDY pigs and wild-type (WT) littermate controls were analyzed by label-free proteomics to reveal pathways and key drivers significantly affected by chronic insulin deficiency and hyperglycemia.
Project description:To evaluate functional consequences of insulin-deficient diabetes mellitus for adipose tissue, we used a genetically engineered pig model of mutant INS gene induced diabetes of youth (MIDY). Adipose tissue samples of MIDY pigs and wild-type (WT) littermate controls were analyzed by label-free proteomics to reveal pathways and key drivers significantly affected by chronic insulin deficiency and hyperglycemia.
Project description:Physiologically the liver is exposed to higher insulin concentrations than other organs. To evaluate functional consequences of insulin-deficient diabetes mellitus for the liver, we used a genetically engineered pig model of mutant INS gene induced diabetes of youth (MIDY). Liver samples of MIDY pigs and wild-type (WT) littermate controls were analyzed by RNA sequencing, label-free proteomics and targeted metabolomics/lipidomics to reveal pathways and key drivers significantly affected by chronic insulin deficiency and hyperglycemia. Gene set enrichment analysis of the ~500 transcripts that were differently abundant between MIDY and WT samples revealed pathways related to amino acid metabolism, beta-oxidation of fatty acids, gluconeogenesis and ketogenesis to be enriched in MIDY samples, whereas pathways related to extra cellular matrix and inflammation/pathogen defense response were enriched in the WT samples. Reduced insulin receptor activation and phosphorylation of protein kinase B (PKB, AKT) was associated with markedly increased levels of retinol dehydrogenase 16 (RDH16) and 3-hydroxy-3-methylglutaryl-CoA synthase (HMGCS2), the apparent key drivers of stimulated gluconeogenesis and ketogenesis in MIDY pigs. Profiling of acylcarnitines provided evidence for increased activity of carnitine palmitoyltransferase 1 (CPT1) shuttling fatty acids into the mitochondrial matrix for beta-oxidation and for increased omega-oxidation. In addition, several enzymes involved in amino acid degradation and enzymes of the urea cycle were increased in abundance, consistent with an increased use of amino acids for gluconeogenesis. Transcripts and proteins related to extracellular matrix, such as collagens, and inflammatory/immune mechanisms, such as C-reactive protein, proteins involved in or regulated by Toll-like receptor signaling and components of major histocompatibility complexes, were less abundant in MIDY vs. WT liver samples. Our study provides the first multi-omics analysis of liver in a clinically relevant large animal model for insulin-deficient diabetes mellitus. Overall design: Hepatic mRNA profiles of 2-year old wild type (WT; N=5) and C94Y transgenic (MIDY; N=4) pigs.
Project description:BACKGROUND:Identification of islet ? cell death prior to the onset of type 1 diabetes (T1D) or type 2 diabetes (T2D) might allow for interventions to protect ? cells and reduce diabetes risk. Circulating unmethylated DNA fragments arising from the human INS gene have been proposed as biomarkers of ? cell death, but this gene alone may not be sufficiently specific to report ? cell death. RESULTS:To identify new candidate genes whose CpG sites may show greater specificity for ? cells, we performed unbiased DNA methylation analysis using the Infinium HumanMethylation 450 array on 64 human islet preparations and 27 non-islet human tissues. For verification of array results, bisulfite DNA sequencing of human ? cells and 11 non-? cell tissues was performed on 5 of the top 10 CpG sites that were found to be differentially methylated. We identified the CHTOP gene as a candidate whose CpGs show a greater frequency of unmethylation in human islets. A digital PCR strategy was used to determine the methylation pattern of CHTOP and INS CpG sites in primary human tissues. Although both INS and CHTOP contained unmethylated CpG sites in non-islet tissues, they occurred in a non-overlapping pattern. Based on Naïve Bayes classifier analysis, the two genes together report 100% specificity for islet damage. Digital PCR was then performed on cell-free DNA from serum from human subjects. Compared to healthy controls (N = 10), differentially methylated CHTOP and INS levels were higher in youth with new onset T1D (N = 43) and, unexpectedly, in healthy autoantibody-negative youth who have first-degree relatives with T1D (N = 23). When tested in lean (N = 32) and obese (N = 118) youth, increased levels of unmethylated INS and CHTOP were observed in obese individuals. CONCLUSION:Our data suggest that concurrent measurement of circulating unmethylated INS and CHTOP has the potential to detect islet death in youth at risk for both T1D and T2D. Our data also support the use of multiple parameters to increase the confidence of detecting islet damage in individuals at risk for developing diabetes.
Project description:Recently, a syndrome of Mutant INS-gene-induced Diabetes of Youth (MIDY, derived from one of 26 distinct mutations) has been identified as a cause of insulin-deficient diabetes, resulting from expression of a misfolded mutant proinsulin protein in the endoplasmic reticulum (ER) of insulin-producing pancreatic beta cells. Genetic deletion of one, two, or even three alleles encoding insulin in mice does not necessarily lead to diabetes. Yet MIDY patients are INS-gene heterozygotes; inheritance of even one MIDY allele, causes diabetes. Although a favored explanation for the onset of diabetes is that insurmountable ER stress and ER stress response from the mutant proinsulin causes a net loss of beta cells, in this report we present three surprising and interlinked discoveries. First, in the presence of MIDY mutants, an increased fraction of wild-type proinsulin becomes recruited into nonnative disulfide-linked protein complexes. Second, regardless of whether MIDY mutations result in the loss, or creation, of an extra unpaired cysteine within proinsulin, Cys residues in the mutant protein are nevertheless essential in causing intracellular entrapment of co-expressed wild-type proinsulin, blocking insulin production. Third, while each of the MIDY mutants induces ER stress and ER stress response; ER stress and ER stress response alone appear insufficient to account for blockade of wild-type proinsulin. While there is general agreement that ultimately, as diabetes progresses, a significant loss of beta cell mass occurs, the early events described herein precede cell death and loss of beta cell mass. We conclude that the molecular pathogenesis of MIDY is initiated by perturbation of the disulfide-coupled folding pathway of wild-type proinsulin.
Project description:A novel Ins(1,3,4,5)P4-binding protein has been purified to apparent homogeneity from solubilized membranes derived from pig platelets. It has a high affinity for Ins(1,3,4,5)P4 (Kd 6.3 +/- 0.4 nM), a Bmax of 2.5-6.0 nmol/mg of protein, and a high specificity for Ins(1,3,4,5)P4 [Kd values for Ins(1,3,4,5,6)P5, InsP6, GroPtdIns(3,4,5)P3, Ins(1,4,5)P3, Ins(3,4,5,6)P4 and L-Ins(1,3,4,5)P4 of 85.0 +/- 4.1 nM, 800.0 +/- 20.2 nM, 65.6 +/- 2.6 nM, > 10 microM, 793.3 +/- 55.6 nM and 81.0 +/- 5.9 nM respectively]. The protein has an apparent molecular mass of 104 kDa, suggesting that this peripheral tissue protein may be different from Ins(1,3,4,5)P4 binding proteins previously isolated from neuronal tissues.
Project description:The prevalence of diabetes mellitus and associated complications is steadily increasing. As a resource for studying systemic consequences of chronic insulin insufficiency and hyperglycemia, we established a comprehensive biobank of long-term diabetic INSC94Y transgenic pigs, a model of mutant INS gene-induced diabetes of youth (MIDY), and of wild-type (WT) littermates.Female MIDY pigs (n = 4) were maintained with suboptimal insulin treatment for 2 years, together with female WT littermates (n = 5). Plasma insulin, C-peptide and glucagon levels were regularly determined using specific immunoassays. In addition, clinical chemical, targeted metabolomics, and lipidomics analyses were performed. At age 2 years, all pigs were euthanized, necropsied, and a broad spectrum of tissues was taken by systematic uniform random sampling procedures. Total beta cell volume was determined by stereological methods. A pilot proteome analysis of pancreas, liver, and kidney cortex was performed by label free proteomics.MIDY pigs had elevated fasting plasma glucose and fructosamine concentrations, C-peptide levels that decreased with age and were undetectable at 2 years, and an 82% reduced total beta cell volume compared to WT. Plasma glucagon and beta hydroxybutyrate levels of MIDY pigs were chronically elevated, reflecting hallmarks of poorly controlled diabetes in humans. In total, ?1900 samples of different body fluids (blood, serum, plasma, urine, cerebrospinal fluid, and synovial fluid) as well as ?17,000 samples from ?50 different tissues and organs were preserved to facilitate a plethora of morphological and molecular analyses. Principal component analyses of plasma targeted metabolomics and lipidomics data and of proteome profiles from pancreas, liver, and kidney cortex clearly separated MIDY and WT samples.The broad spectrum of well-defined biosamples in the Munich MIDY Pig Biobank that will be available to the scientific community provides a unique resource for systematic studies of organ crosstalk in diabetes in a multi-organ, multi-omics dimension.
Project description:3-Deoxyglucosone reductase activity in the extracts of rat, pig and human livers was potently inhibited by aldehyde reductase inhibitors. The major species of 3-deoxyglucosone reductase purified from human and pig livers were biochemically and immunochemically identical with aldehyde reductase. The two enzymes and rat liver aldehyde reductase exhibited higher catalytic efficiency for 3-deoxyglucosone than for D-glucuronate, a representative substrate of aldehyde reductase.
Project description:Ins(1,3,4,5)P4 was able to mobilize the entire Ins(1,4,5)P3-sensitive intracellular Ca2+ store in saponin-permeabilized SH-SY5Y human neuroblastoma cells in a concentration-dependent manner, yielding an EC50 value of 2.05 +/- 0.45 microM, compared with 0.14 +/- 0.03 microM for Ins(1,4,5)P3. However, L-Ins(1,3,4,5)P4 [= D-Ins(1,3,5,6)P4] failed to cause mobilization of intracellular Ca2+ at concentrations up to 100 microM. Binding studies using pig cerebellar membranes as a source of both Ins(1,4,5)P3/Ins(1,3,4,5)P4-specific binding sites have revealed a marked contrast in their stereospecificity requirements. Ins(1,4,5)P3-receptors from pig cerebella exhibited stringent stereospecificity, L-Ins(1,4,5)P3 and L-Ins(1,3,4,5)P4 were > 1000-fold weaker, whereas Ins(1,3,4,5)P4 (IC50 762 +/- 15 nM) was only about 40-fold weaker than D-Ins(1,4,5)P3 (IC50 20.7 +/- 9.7 nM) at displacing specific [3H]Ins(1,4,5)P3 binding from an apparently homogeneous Ins(1,4,5)P3 receptor population. In contrast, the Ins(1,3,4,5)P4-binding site exhibited poor stereoselectivity. Ins(1,3,4,5)P4 produced a biphasic displacement of specific [32P]Ins(1,3,4,5)P4 binding, with two-site analysis revealing KD values for high- and low-affinity sites of 2.1 +/- 0.5 nM and 918 +/- 161 nM respectively. L-Ins(1,3,4,5)P4 also produced a biphasic displacement of specific [32P]Ins(1,3,4,5)P4 binding which was less than 10-fold weaker than with D-Ins(1,3,4,5)P4 (IC50 values for the high- and low-affinity sites of 17.2 +/- 3.7 nM and 3010 +/- 542 nM respectively). Therefore, although L-Ins(1,3,4,5)P4 appears to be a high-affinity Ins(1,3,4,5)P4-binding-site ligand in pig cerebellum, it is a very weak agonist at the Ca(2+)-mobilizing receptors of permeabilized SH-SY5Y cells. We suggest that the ability of D-Ins(1,3,4,5)P4 to access intracellular Ca2+ stores may derive from specific interaction with the Ins(1,4,5)P3- and not the Ins(1,3,4,5)P4-receptor population.
Project description:Neonatal diabetes mellitus (NDM) is defined as diabetes with onset before 6?months of age. Nearly half of individuals with NDM are affected by permanent neonatal diabetes mellitus (PNDM). Mutations in KATP channel genes (KCNJ11, ABCC8) and the insulin gene (INS) are the most common causes of PNDM.To estimate the prevalence of PNDM among SEARCH for Diabetes in Youth (SEARCH) study participants (2001-2008) and to identify the genetic mutations causing PNDM.SEARCH is a multicenter population-based study of diabetes in youth <20?yr of age. Participants diagnosed with diabetes before 6?months of age were invited for genetic testing for mutations in the KCNJ11, ABCC8, and INS genes.Of the 15,829 SEARCH participants with diabetes, 39 were diagnosed before 6?months of age. Thirty-five of them had PNDM (0.22% of all diabetes cases in SEARCH), 3 had transient neonatal diabetes that had remitted by 18?months and 1 was unknown. The majority of them (66.7%) had a clinical diagnosis of type1 diabetes by their health care provider. Population prevalence of PNDM in youth <20?yr was estimated at 1 in 252?000. Seven participants underwent genetic testing; mutations causing PNDM were identified in five (71%), (two KCNJ11, three INS).We report the first population-based frequency of PNDM in the US based on the frequency of PNDM in SEARCH. Patients with NDM are often misclassified as having type1 diabetes. Widespread education is essential to encourage appropriate genetic testing and treatment of NDM.