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1.
Reprod Biol ; 24(1): 100850, 2024 Mar.
Article in English | MEDLINE | ID: mdl-38262267

ABSTRACT

Gestational diabetes mellitus (GDM) is a prevalent metabolic disturbance in pregnancy. This article investigated the correlations between serum IGF1R and ATG7 with insulin resistance (IR) in GDM patients. Firstly, 100 GDM patients and 100 healthy pregnant women were selected as study subjects. The levels of serum IGF1, IGF1R, and ATG7 and their correlations with the insulin resistance index homeostasis model assessment of insulin resistance (HOMA-IR) were measured and analyzed by ELISA and Pearson. Additionally, in mouse pancreatic ß cells, IGF1R, ATG7, Beclin-1, and LC3-II/LC3-I levels, cell viability/apoptosis, and insulin level were assessed by western blot, CCK-8, flow cytometry, and ELISA. The GDM group exhibited obviously raised serum IGF1 level and diminished serum IGF1R/ATG7 levels. The IGF1 level was positively correlated with HOMA-IR, while IGF1R/ATG7 levels were negatively correlated with HOMA-IR in GDM patients. Collectively, IGF1R stimulated cell viability, suppressed apoptosis, amplified insulin secretion, and increased ATG7 expression to induce cell autophagy, which could be partially averted by ATG7 silencing.


Subject(s)
Diabetes, Gestational , Insulin Resistance , Insulin-Secreting Cells , Animals , Mice , Pregnancy , Humans , Female , Diabetes, Gestational/metabolism , Insulin Secretion , Insulin-Secreting Cells/chemistry , Insulin-Secreting Cells/metabolism , Blood Glucose/analysis , Blood Glucose/metabolism , Insulin , Receptor, IGF Type 1/metabolism
2.
Proc Natl Acad Sci U S A ; 119(31): e2204407119, 2022 08 02.
Article in English | MEDLINE | ID: mdl-35881794

ABSTRACT

Cellular metabolism is regulated over space and time to ensure that energy production is efficiently matched with consumption. Fluorescent biosensors are useful tools for studying metabolism as they enable real-time detection of metabolite abundance with single-cell resolution. For monitoring glycolysis, the intermediate fructose 1,6-bisphosphate (FBP) is a particularly informative signal as its concentration is strongly correlated with flux through the whole pathway. Using GFP insertion into the ligand-binding domain of the Bacillus subtilis transcriptional regulator CggR, we developed a fluorescent biosensor for FBP termed HYlight. We demonstrate that HYlight can reliably report the real-time dynamics of glycolysis in living cells and tissues, driven by various metabolic or pharmacological perturbations, alone or in combination with other physiologically relevant signals. Using this sensor, we uncovered previously unknown aspects of ß-cell glycolytic heterogeneity and dynamics.


Subject(s)
Biosensing Techniques , Fructose , Glycolysis , Single-Cell Analysis , Fluorescence , Fructose/analysis , Fructosediphosphates/analysis , Humans , Insulin-Secreting Cells/chemistry , Insulin-Secreting Cells/metabolism , Repressor Proteins/chemistry , Repressor Proteins/genetics , Single-Cell Analysis/methods
3.
Diabetes ; 71(3): 394-411, 2022 03 01.
Article in English | MEDLINE | ID: mdl-35029277

ABSTRACT

Pancreatic ß-cells adapt to compensate for increased metabolic demand during obesity. Although the miRNA pathway has an essential role in ß-cell expansion, whether it is involved in adaptive proliferation is largely unknown. First, we report that EGR2 binding to the miR-455 promoter induced miR-455 upregulation in the pancreatic islets of obesity mouse models. Then, in vitro gain- or loss-of-function studies showed that miR-455 overexpression facilitated ß-cell proliferation. Knockdown of miR-455 in ob/ob mice via pancreatic intraductal infusion prevented compensatory ß-cell expansion. Mechanistically, our results revealed that increased miR-455 expression inhibits the expression of its target cytoplasmic polyadenylation element binding protein 1 (CPEB1), an mRNA binding protein that plays an important role in regulating insulin resistance and cell proliferation. Decreased CPEB1 expression inhibits elongation of the poly(A) tail and the subsequent translation of Cdkn1b mRNA, reducing the CDKN1B expression level and finally promoting ß-cell proliferation. Taken together, our results show that the miR-455/CPEB1/CDKN1B pathway contributes to adaptive proliferation of ß-cells to meet metabolic demand during obesity.


Subject(s)
Cyclin-Dependent Kinase Inhibitor p27/physiology , Insulin-Secreting Cells/pathology , MicroRNAs/physiology , Obesity/genetics , Signal Transduction/physiology , Transcription Factors/physiology , mRNA Cleavage and Polyadenylation Factors/physiology , Animals , Cell Proliferation/genetics , Cyclin-Dependent Kinase Inhibitor p27/genetics , Humans , Insulin-Secreting Cells/chemistry , Insulin-Secreting Cells/metabolism , Male , Mice , Mice, Inbred C57BL , Mice, Knockout , Mice, Obese , MicroRNAs/genetics , Obesity/pathology , RNA, Messenger/analysis , Transcription Factors/genetics , Up-Regulation , mRNA Cleavage and Polyadenylation Factors/genetics
4.
Molecules ; 26(5)2021 Mar 06.
Article in English | MEDLINE | ID: mdl-33800801

ABSTRACT

Diabetes remains one of the fastest growing chronic diseases and is a leading source of morbidity and accelerated mortality in the world. Loss of beta cell mass (BCM) and decreased sensitivity to insulin underlie diabetes pathogenesis. Yet, the ability to safely and directly assess BCM in individuals with diabetes does not exist. Measures such as blood glucose provide only a crude indirect picture of beta cell health. PET imaging could, in theory, allow for safe, direct, and precise characterization of BCM. However, identification of beta cell-specific radiolabeled tracers remains elusive. G-protein coupled receptor 44 (GPR44) is a transmembrane protein that was characterized in 2012 as highly beta cell-specific within the insulin-positive islets of Langerhans. Accordingly, radiolabeling of existing GPR44 antagonists could be a viable method to accelerate PET tracer development. The present study aims to evaluate and summarize published analogues of the GPR44 antagonist ramatroban to develop 18F-labeled PET tracers for BCM analysis. The 77 corresponding ramatroban analogues containing a fluorine nuclide were characterized for properties including binding affinity, selectivity, and pharmacokinetic and metabolic profile, and 32 compounds with favorable properties were identified. This review illustrates the potential of GPR44 analogues for the development of PET tracers.


Subject(s)
Carbazoles/chemistry , Fluorine Radioisotopes/metabolism , Insulin-Secreting Cells/metabolism , Positron-Emission Tomography/methods , Radioactive Tracers , Radiopharmaceuticals/metabolism , Receptors, Immunologic/metabolism , Receptors, Prostaglandin/metabolism , Sulfonamides/chemistry , Humans , Insulin-Secreting Cells/chemistry , Insulin-Secreting Cells/cytology , Platelet Aggregation Inhibitors/chemistry
5.
J Endocrinol ; 247(1): 87, 2020 10.
Article in English | MEDLINE | ID: mdl-32755994

ABSTRACT

Toll-like receptors (TLRs), particularly TLR4, may act as immune sensors for metabolic stress signals such as lipids and link tissue metabolic changes to innate immunity. TLR signalling is not only tissue-dependent but also cell-type dependent and recent studies suggest that TLRs are not restricted to innate immune cells alone. Pancreatic islets, a hub of metabolic hormones and cytokines, respond to TLR signalling. However, the source of TLR signalling within the islet remain poorly understood. Uncovering the specific cell source and its role in mediating TLR signalling, especially within type 2 diabetes (T2D) islet will yield new targets to tackle islet inflammation, hormone secretion dysregulation and ultimately diabetes. In the present study, we immuno-characterised TLRs linked to pancreatic islets in both healthy and obese diabetic mice. We found that while TLRs1-4 and TLR9 were expressed in mouse islets, these TLRs did not co-localise with insulin-producing ß-cells. ß-Cells from obese diabetic mice were also devoid of these TLRs. While TLR immunoreactivity in obese mice islets increased, this was driven mostly by increased islet endothelial cell and islet macrophage presence. Analysis of human islet single-cell RNA-seq databases revealed that macrophages were an important source of islet TLRs. However, only TLR4 and TLR8 showed variation and cell-type specificity in their expression patterns. Cell depletion experiments in isolated mouse islets showed that TLR4 signalled through macrophages to alter islet cytokine secretome. Together, these studies suggest that islet macrophages are a dominant source of TLR4-mediated signalling in both healthy and diabetic islets.


Subject(s)
Cytokines/metabolism , Diabetes Mellitus, Type 2/metabolism , Islets of Langerhans/pathology , Macrophages/metabolism , Signal Transduction/physiology , Toll-Like Receptor 4/metabolism , Animals , Endothelial Cells/chemistry , Humans , Insulin-Secreting Cells/chemistry , Islets of Langerhans/chemistry , Macrophages/chemistry , Male , Mice , Obesity/metabolism , RNA, Messenger/analysis , Toll-Like Receptor 4/analysis , Toll-Like Receptor 4/genetics
6.
Biomolecules ; 10(9)2020 08 19.
Article in English | MEDLINE | ID: mdl-32824918

ABSTRACT

Human islet amyloid polypeptide (hIAPP) corresponds to a 37-residue hormone present in insulin granules that maintains a high propensity to form ß-sheet structures during co-secretion with insulin. Previously, employing a biomimetic approach, we proposed a panel of optimized IAPP sequences with only one residue substitution that shows the capability to reduce amyloidogenesis. Taking into account that specific membrane lipids have been considered as a key factor in the induction of cytotoxicity, in this study, following the same design strategy, we characterize the effect of a series of lipids upon several polypeptide domains that show the highest aggregation propensity. The characterization of the C-native segment of hIAPP (residues F23-Y37), together with novel variants F23R and I26A allowed us to demonstrate an effect upon the formation of ß-sheet structures. Our results suggest that zwitterionic phospholipids promote adsorption of the C-native segments at the lipid-interface and ß-sheet formation with the exception of the F23R variant. Moreover, the presence of cholesterol did not modify this behavior, and the ß-sheet structural transitions were not registered when the N-terminal domain of hIAPP (K1-S20) was characterized. Considering that insulin granules are enriched in phosphatidylserine (PS), the property of lipid vesicles containing negatively charged lipids was also evaluated. We found that these types of lipids promote ß-sheet conformational transitions in both the C-native segment and the new variants. Furthermore, these PS/peptides arrangements are internalized in Langerhans islet ß-cells, localized in the endoplasmic reticulum, and trigger critical pathways such as unfolded protein response (UPR), affecting insulin secretion. Since this phenomenon was associated with the presence of cytotoxicity on Langerhans islet ß-cells, it can be concluded that the anionic lipid environment and degree of solvation are critical conditions for the stability of segments with the propensity to form ß-sheet structures, a situation that will eventually affect the structural characteristics and stability of IAPP within insulin granules, thus modifying the insulin secretion.


Subject(s)
Homeostasis , Insulin-Secreting Cells/metabolism , Islet Amyloid Polypeptide/metabolism , Lipids/chemistry , Humans , Insulin-Secreting Cells/chemistry , Islet Amyloid Polypeptide/chemistry , Protein Conformation, beta-Strand
7.
EBioMedicine ; 58: 102895, 2020 Aug.
Article in English | MEDLINE | ID: mdl-32739864

ABSTRACT

BACKGROUND: Bariatric surgery is an effective treatment for type 2 diabetes. Early post-surgical enhancement of insulin secretion is key for diabetes remission. The full complement of mechanisms responsible for improved pancreatic beta cell functionality after bariatric surgery is still unclear. Our aim was to identify pathways, evident in the islet transcriptome, that characterize the adaptive response to bariatric surgery independently of body weight changes. METHODS: We performed entero-gastro-anastomosis (EGA) with pyloric ligature in leptin-deficient ob/ob mice as a surrogate of Roux-en-Y gastric bypass (RYGB) in humans. Multiple approaches such as determination of glucose tolerance, GLP-1 and insulin secretion, whole body insulin sensitivity, ex vivo glucose-stimulated insulin secretion (GSIS) and functional multicellular Ca2+-imaging, profiling of mRNA and of miRNA expression were utilized to identify significant biological processes involved in pancreatic islet recovery. FINDINGS: EGA resolved diabetes, increased pancreatic insulin content and GSIS despite a persistent increase in fat mass, systemic and intra-islet inflammation, and lipotoxicity. Surgery differentially regulated 193 genes in the islet, most of which were involved in the regulation of glucose metabolism, insulin secretion, calcium signaling or beta cell viability, and these were normalized alongside changes in glucose metabolism, intracellular Ca2+ dynamics and the threshold for GSIS. Furthermore, 27 islet miRNAs were differentially regulated, four of them hubs in a miRNA-gene interaction network and four others part of a blood signature of diabetes resolution in ob/ob mice and in humans. INTERPRETATION: Taken together, our data highlight novel miRNA-gene interactions in the pancreatic islet during the resolution of diabetes after bariatric surgery that form part of a blood signature of diabetes reversal. FUNDING: European Union's Horizon 2020 research and innovation programme via the Innovative Medicines Initiative 2 Joint Undertaking (RHAPSODY), INSERM, Société Francophone du Diabète, Institut Benjamin Delessert, Wellcome Trust Investigator Award (212625/Z/18/Z), MRC Programme grants (MR/R022259/1, MR/J0003042/1, MR/L020149/1), Diabetes UK (BDA/11/0004210, BDA/15/0005275, BDA 16/0005485) project grants, National Science Foundation (310030-188447), Fondation de l'Avenir.


Subject(s)
Diabetes Mellitus, Type 2/surgery , Gene Regulatory Networks , Insulin-Secreting Cells/chemistry , MicroRNAs/genetics , Obesity/surgery , Animals , Diabetes Mellitus, Type 2/genetics , Diabetes Mellitus, Type 2/metabolism , Disease Models, Animal , Gastric Bypass , Gene Expression Profiling , Gene Expression Regulation , Glucagon-Like Peptide 1/metabolism , Glucose Tolerance Test , Humans , Insulin/metabolism , Male , Mice , Mice, Obese , Obesity/genetics , Obesity/metabolism
8.
Methods Mol Biol ; 2128: 25-54, 2020.
Article in English | MEDLINE | ID: mdl-32180184

ABSTRACT

The polygenic background of selectively bred diabetes models mimics the etiology of type 2 diabetes. So far, three different rodent models (Goto-Kakizaki rats, Nagoya-Shibata-Yasuda mice, and Oikawa-Nagao mice) have been established in the diabetes research field by continuous selective breeding for glucose tolerance from outbred rodent stocks. The origin of hyperglycemia in these rodents is mainly insulin secretion deficiency from the pancreatic ß-cells and mild insulin resistance in insulin target organs. In this chapter, we summarize backgrounds and phenotypes of these rodent models to highlight their importance in diabetes research. Then, we introduce experimental methodologies to evaluate ß-cell exocytosis as a putative common defect observed in these rodent models.


Subject(s)
Diabetes Mellitus, Experimental/genetics , Selective Breeding/genetics , Animals , Diabetes Mellitus, Experimental/etiology , Diabetes Mellitus, Experimental/metabolism , Diabetes Mellitus, Type 1/etiology , Diabetes Mellitus, Type 1/genetics , Diabetes Mellitus, Type 1/metabolism , Diabetes Mellitus, Type 2/etiology , Diabetes Mellitus, Type 2/genetics , Diabetes Mellitus, Type 2/metabolism , Exocytosis , Gene Expression Profiling/methods , Glucose Intolerance , Insulin Resistance/physiology , Insulin Secretion/physiology , Insulin-Secreting Cells/chemistry , Insulin-Secreting Cells/cytology , Insulin-Secreting Cells/metabolism , Insulin-Secreting Cells/physiology , Mice , Mice, Inbred C3H , Patch-Clamp Techniques/methods , Phenotype , Rats , Rats, Wistar
9.
Methods Mol Biol ; 2128: 159-179, 2020.
Article in English | MEDLINE | ID: mdl-32180193

ABSTRACT

During embryogenesis, beta-cells arise from the dorsal and ventral bud originating in the endoderm germ layer. As the animal develops to adulthood, the beta-cell mass dramatically increases. The expansion of the beta-cell population is driven by cell division among the embryonic beta-cells and supplanted by neogenesis from post-embryonic progenitors. Here, we describe a protocol for multicolor clonal analysis in zebrafish to define the contribution of individual embryonic beta-cells to the increase in cell numbers. This technique provides insights into the proliferative history of individual beta-cells in an islet. This insight helps in defining the replicative heterogeneity among individual beta-cells during development. Additionally, the ability to discriminate individual cells based on unique color signatures helps quantify the volume occupied by beta-cells and define the contribution of cellular size to the beta-cell mass.


Subject(s)
Cell Proliferation , Cell Tracking/methods , Image Processing, Computer-Assisted/methods , Insulin-Secreting Cells/cytology , Microscopy, Confocal/methods , Staining and Labeling/methods , Animals , Animals, Genetically Modified , Cell Lineage , Cloning, Molecular/methods , Color , Genes, Reporter , Insulin-Secreting Cells/chemistry , Integrases , Luminescent Proteins/genetics , Luminescent Proteins/metabolism , Models, Animal , Zebrafish
10.
Curr Drug Targets ; 21(7): 722-734, 2020.
Article in English | MEDLINE | ID: mdl-31886749

ABSTRACT

micro (mi)-RNAs are vital regulators of multiple processes including insulin signaling pathways and glucose metabolism. Pancreatic ß-cells function is dependent on some miRNAs and their target mRNA, which together form a complex regulative network. Several miRNAs are known to be directly involved in ß-cells functions such as insulin expression and secretion. These small RNAs may also play significant roles in the fate of ß-cells such as proliferation, differentiation, survival and apoptosis. Among the miRNAs, miR-7, miR-9, miR-375, miR-130 and miR-124 are of particular interest due to being highly expressed in these cells. Under diabetic conditions, although no specific miRNA profile has been noticed, the expression of some miRNAs and their target mRNAs are altered by posttranscriptional mechanisms, exerting diverse signs in the pathobiology of various diabetic complications. The aim of this review article is to discuss miRNAs involved in the process of stem cells differentiation into ß-cells, resulting in enhanced ß-cell functions with respect to diabetic disorders. This paper will also look into the impact of miRNA expression patterns on in vitro proliferation and differentiation of ß-cells. The efficacy of the computational genomics and biochemical analysis to link the changes in miRNA expression profiles of stem cell-derived ß-cells to therapeutically relevant outputs will be discussed as well.


Subject(s)
Diabetes Mellitus/therapy , Insulin-Secreting Cells/chemistry , Insulin-Secreting Cells/metabolism , Insulin/biosynthesis , MicroRNAs/biosynthesis , MicroRNAs/therapeutic use , Animals , Cell Differentiation , Diabetes Complications/genetics , Diabetes Mellitus/genetics , Humans , Insulin-Secreting Cells/cytology , Insulin-Secreting Cells/drug effects
11.
Biometals ; 32(6): 951-964, 2019 12.
Article in English | MEDLINE | ID: mdl-31754889

ABSTRACT

The understanding of cellular Cd2+ accumulation and toxicity is hampered by a lack of fluorescent indicators selective for intracellular free Cd2+ ([Cd2+]i). In this study, we used depolarized MIN6 mouse pancreatic beta cells as a model for evaluating [Cd2+]i detection with commercially available fluorescent probes, most of which have been traditionally used to visualize [Ca2+]i and [Zn2+]i. We trialed a panel of 12 probes including fura-2, FluoZin-3, Leadmium Green, Rhod-5N, indo-1, Fluo-5N, and others. We found that the [Zn2+]i probe FluoZin-3 and the traditional [Ca2+]i probe fura-2 responded most consistently and robustly to [Cd2+]i accumulation mediated by voltage-gated calcium channels. While selective detection of [Cd2+]i by fura-2 required the omission of Ca2+ from extracellular buffers, FluoZin-3 responded to [Cd2+]i similarly in the presence or absence of extracellular Ca2+. Furthermore, we showed that FluoZin-3 and fura-2 can be used together for simultaneous monitoring of [Ca2+]i and [Cd2+]i in the same cells. None of the other fluorophores tested were effective [Cd2+]i detectors in this model.


Subject(s)
Cadmium/analysis , Fluorescent Dyes/analysis , Fura-2/analysis , Insulin-Secreting Cells/chemistry , Insulin-Secreting Cells/metabolism , Polycyclic Compounds/analysis , Animals , Cadmium/metabolism , Cell Line , Fluorescent Dyes/chemistry , Fura-2/chemistry , Mass Spectrometry , Mice , Microscopy, Fluorescence , Polycyclic Compounds/chemistry
12.
Molecules ; 24(20)2019 Oct 17.
Article in English | MEDLINE | ID: mdl-31627330

ABSTRACT

Modern omics techniques reveal molecular structures and cellular networks of tissues and cells in unprecedented detail. Recent advances in single cell analysis have further revolutionized all disciplines in cellular and molecular biology. These methods have also been employed in current investigations on the structure and function of insulin secreting beta cells under normal and pathological conditions that lead to an impaired glucose tolerance and type 2 diabetes. Proteomic and transcriptomic analyses have pointed to significant alterations in protein expression and function in beta cells exposed to diabetes like conditions (e.g., high glucose and/or saturated fatty acids levels). These nutritional overload stressful conditions are often defined as glucolipotoxic due to the progressive damage they cause to the cells. Our recent studies on the rat insulinoma-derived INS-1E beta cell line point to differential effects of such conditions in the phospholipid bilayers in beta cells. This review focuses on confocal microscopy-based detection of these profound alterations in the plasma membrane and membranes of insulin granules and lipid droplets in single beta cells under such nutritional load conditions.


Subject(s)
Diabetes Mellitus, Type 2/metabolism , Fatty Acids/metabolism , Glucose Intolerance/metabolism , Glucose/metabolism , Insulin-Secreting Cells/metabolism , Insulin/metabolism , Animals , Cell Line, Tumor , Cell Membrane/chemistry , Cell Membrane/metabolism , Cytoplasmic Granules/metabolism , Cytoplasmic Granules/pathology , Diabetes Mellitus, Type 2/physiopathology , Glucose/pharmacology , Glucose Intolerance/physiopathology , Humans , Insulin-Secreting Cells/chemistry , Insulin-Secreting Cells/pathology , Lipid Droplets/metabolism , Lipid Droplets/pathology , Lipid Metabolism , Lipidomics/methods , Phospholipids/metabolism , Rats , Single-Cell Analysis
13.
Magn Reson Med ; 82(2): 763-774, 2019 08.
Article in English | MEDLINE | ID: mdl-30957300

ABSTRACT

PURPOSE: The purpose of this study was to investigate the feasibility of in vivo imaging of human pancreatic ductal cells by OATP1B3 reporter gene under MRI. METHODS: A human cell line (PANC-1) derived from the pancreatic ductal epithelium was used in this study. After transduction of OATP1B3, the cellular physiological functions and the ability of intracellular uptake of the MRI contrast medium (Gd-EOB-DTPA) were examined. Induced differentiation of the PANC-1 cells into hormone-secreting cells were performed to simulate pancreatic ß-like cells. The hormone-secreting cells were implanted into rats and in vivo MRI was evaluated. RESULTS: The mRNA and proteins of OATP1B3 were highly expressed. No significant change of cellular physiological functions was found after the expression. After induced differentiation, the hormone secretion capacities of the OATP1B3-expressing PANC-1 cells were confirmed. Intra-cellular uptake of Gd-EOB-DTPA was determined in vitro by inductively coupled plasma mass spectrometry and MRI. In vivo MRI of the OATP1B3-expressing xenograft revealed an increased signal intensity after contrast enhancement. CONCLUSION: OATP1B3 can be used as a safe and feasible in vivo MRI gene reporter for human pancreatic ductal cells.


Subject(s)
Genes, Reporter/genetics , Insulin-Secreting Cells/metabolism , Insulin/metabolism , Magnetic Resonance Imaging/methods , Animals , Cell Line , Contrast Media , Feasibility Studies , Female , Gadolinium DTPA , Heterografts/chemistry , Heterografts/diagnostic imaging , Heterografts/metabolism , Humans , Insulin-Secreting Cells/chemistry , Mice , Mice, SCID , Molecular Imaging , Rats , Solute Carrier Organic Anion Transporter Family Member 1B3/chemistry , Solute Carrier Organic Anion Transporter Family Member 1B3/genetics , Solute Carrier Organic Anion Transporter Family Member 1B3/metabolism
14.
Cell Metab ; 29(6): 1422-1432.e3, 2019 06 04.
Article in English | MEDLINE | ID: mdl-30879985

ABSTRACT

Progressive decline of pancreatic beta cell function is central to the pathogenesis of type 2 diabetes. Protein phosphorylation regulates glucose-stimulated insulin secretion from beta cells, but how signaling networks are remodeled in diabetic islets in vivo remains unknown. Using high-sensitivity mass spectrometry-based proteomics, we quantified 6,500 proteins and 13,000 phosphopeptides in islets of obese diabetic mice and matched controls, revealing drastic remodeling of key kinase hubs and signaling pathways. Integration with a literature-derived signaling network implicated GSK3 kinase in the control of the beta cell-specific transcription factor PDX1. Deep phosphoproteomic analysis of human islets chronically treated with high glucose demonstrated a conserved glucotoxicity-dependent role of GSK3 kinase in regulating insulin secretion. Remarkably, the ability of beta cells to secrete insulin in response to glucose was rescued almost completely by pharmacological inhibition of GSK3. Thus, our resource enables investigation of mechanisms and drug targets in type 2 diabetes.


Subject(s)
Diabetes Mellitus, Experimental/metabolism , Glycogen Synthase Kinase 3/metabolism , Homeodomain Proteins/metabolism , Insulin-Secreting Cells/metabolism , Islets of Langerhans/metabolism , Trans-Activators/metabolism , Animals , Cells, Cultured , Diabetes Mellitus, Experimental/genetics , Diabetes Mellitus, Experimental/pathology , Diabetes Mellitus, Type 2/genetics , Diabetes Mellitus, Type 2/metabolism , Diabetes Mellitus, Type 2/pathology , Glycogen Synthase Kinase 3/genetics , Homeodomain Proteins/genetics , Humans , Insulin Secretion/genetics , Insulin-Secreting Cells/chemistry , Insulin-Secreting Cells/pathology , Islets of Langerhans/chemistry , Islets of Langerhans/pathology , Mice , Mice, Inbred C57BL , Mice, Transgenic , Phosphoproteins/analysis , Phosphoproteins/metabolism , Phosphorylation , Protein Processing, Post-Translational , Proteomics/methods , Receptors, Leptin/genetics , Signal Transduction , Trans-Activators/genetics
15.
Elife ; 72018 11 09.
Article in English | MEDLINE | ID: mdl-30412052

ABSTRACT

Insulin gene mutations are a leading cause of neonatal diabetes. They can lead to proinsulin misfolding and its retention in endoplasmic reticulum (ER). This results in increased ER-stress suggested to trigger beta-cell apoptosis. In humans, the mechanisms underlying beta-cell failure remain unclear. Here we show that misfolded proinsulin impairs developing beta-cell proliferation without increasing apoptosis. We generated induced pluripotent stem cells (iPSCs) from people carrying insulin (INS) mutations, engineered isogenic CRISPR-Cas9 mutation-corrected lines and differentiated them to beta-like cells. Single-cell RNA-sequencing analysis showed increased ER-stress and reduced proliferation in INS-mutant beta-like cells compared with corrected controls. Upon transplantation into mice, INS-mutant grafts presented reduced insulin secretion and aggravated ER-stress. Cell size, mTORC1 signaling, and respiratory chain subunits expression were all reduced in INS-mutant beta-like cells, yet apoptosis was not increased at any stage. Our results demonstrate that neonatal diabetes-associated INS-mutations lead to defective beta-cell mass expansion, contributing to diabetes development.


Subject(s)
Diabetes Mellitus/genetics , Endoplasmic Reticulum Stress/genetics , Induced Pluripotent Stem Cells/chemistry , Proinsulin/genetics , Animals , Apoptosis/genetics , CRISPR-Cas Systems/genetics , Cell Differentiation/genetics , Cell Proliferation/genetics , Diabetes Mellitus/pathology , Endoplasmic Reticulum/genetics , Female , Humans , Induced Pluripotent Stem Cells/metabolism , Infant, Newborn , Insulin-Secreting Cells/chemistry , Insulin-Secreting Cells/metabolism , Male , Mice , Mutation , Proinsulin/chemistry , Protein Folding , Sequence Analysis, RNA , Signal Transduction , Single-Cell Analysis
16.
Int J Mol Sci ; 19(4)2018 Apr 12.
Article in English | MEDLINE | ID: mdl-29649109

ABSTRACT

ß-cell dedifferentiation has been recently suggested as an additional mechanism contributing to type-1 and to type-2 diabetes pathogenesis. Moreover, several studies demonstrated that in vitro culture of native human pancreatic islets derived from non-diabetic donors resulted in the generation of an undifferentiated cell population. Additional evidence from in vitro human ß-cell lineage tracing experiments, demonstrated that dedifferentiated cells derive from ß-cells, thus representing a potential in vitro model of ß-cell dedifferentiation. Here, we report the microRNA expression profiles analysis of in vitro dedifferentiated islet cells in comparison to mature human native pancreatic islets. We identified 13 microRNAs upregulated and 110 downregulated in islet cells upon in vitro dedifferentiation. Interestingly, among upregulated microRNAs, we observed the activation of microRNA miR-302s cluster, previously defined as pluripotency-associated. Bioinformatic analysis indicated that miR-302s are predicted to target several genes involved in the control of ß-cell/epithelial phenotype maintenance; accordingly, such genes were downregulated upon human islet in vitro dedifferentiation. Moreover, we uncovered that cell-cell contacts are needed to maintain low/null expression levels of miR-302. In conclusion, we showed that miR-302 microRNA cluster genes are involved in in vitro dedifferentiation of human pancreatic islet cells and inhibits the expression of multiple genes involved in the maintenance of ß-cell mature phenotype.


Subject(s)
Gene Expression Profiling/methods , Insulin-Secreting Cells/cytology , Islets of Langerhans/cytology , MicroRNAs/genetics , Up-Regulation , Adult , Aged , Aged, 80 and over , Cell Dedifferentiation , Cell Differentiation , Cells, Cultured , Humans , Insulin-Secreting Cells/chemistry , Islets of Langerhans/chemistry , Middle Aged
17.
Trends Biotechnol ; 36(4): 445-456, 2018 04.
Article in English | MEDLINE | ID: mdl-29455936

ABSTRACT

Encapsulating, or immunoisolating, insulin-secreting cells within implantable, semipermeable membranes is an emerging treatment for type 1 diabetes. This approach can eliminate the need for immunosuppressive drug treatments to prevent transplant rejection and overcome the shortage of donor tissues by utilizing cells derived from allogeneic or xenogeneic sources. Encapsulation device designs are being optimized alongside the development of clinically viable, replenishable, insulin-producing stem cells, for the first time creating the possibility of widespread therapeutic use of this technology. Here, we highlight the status of the most advanced and widely explored implementations of cell encapsulation with an eye toward translating the potential of this technological approach to medical reality.


Subject(s)
Bioartificial Organs , Diabetes Mellitus, Experimental/therapy , Diabetes Mellitus, Type 1/therapy , Pancreas, Artificial , Tissue Engineering , Animals , Clinical Trials as Topic , Humans , Insulin-Secreting Cells/chemistry , Insulin-Secreting Cells/transplantation , Materials Testing , Membranes, Artificial , Models, Animal
18.
Sci Rep ; 8(1): 1499, 2018 01 24.
Article in English | MEDLINE | ID: mdl-29367680

ABSTRACT

Olfactory receptors (ORs) mediate olfactory chemo-sensation in OR neurons. Herein, we have demonstrated that the OR chemo-sensing machinery functions in pancreatic ß-cells and modulates insulin secretion. First, we found several OR isoforms, including OLFR15 and OLFR821, to be expressed in pancreatic islets and a ß-cell line, MIN6. Immunostaining revealed OLFR15 and OLFR821 to be uniformly expressed in pancreatic ß-cells. In addition, mRNAs of Olfr15 and Olfr821 were detected in single MIN6 cells. These results indicate that multiple ORs are simultaneously expressed in individual ß-cells. Octanoic acid, which is a medium-chain fatty acid contained in food and reportedly interacts with OLFR15, potentiated glucose-stimulated insulin secretion (GSIS), thereby improving glucose tolerance in vivo. GSIS potentiation by octanoic acid was confirmed in isolated pancreatic islets and MIN6 cells and was blocked by OLFR15 knockdown. While Gα olf expression was not detectable in ß-cells, experiments using inhibitors and siRNA revealed that the pathway dependent on phospholipase C-inositol triphosphate, rather than cAMP-protein kinase A, mediates GSIS potentiation via OLFR15. These findings suggest that the OR system in pancreatic ß-cells has a chemo-sensor function allowing recognition of environmental substances obtained from food, and potentiates insulin secretion in a cell-autonomous manner, thereby modulating systemic glucose metabolism.


Subject(s)
Glucose/metabolism , Insulin-Secreting Cells/chemistry , Insulin-Secreting Cells/drug effects , Insulin/metabolism , Receptors, Odorant/analysis , Animals , Cell Line , Gene Expression Profiling , Immunohistochemistry , Mice , Mice, Inbred C57BL , RNA, Messenger/analysis , Receptors, Odorant/genetics
19.
Diabetes Res Clin Pract ; 131: 1-11, 2017 Sep.
Article in English | MEDLINE | ID: mdl-28666105

ABSTRACT

Type 2 diabetes manifests beta cell deficiencies and alpha cell expansion which is consistent with relative insulin deficiency and glucagon oversecretion. The effects of hyperglycemia on alpha cells are not as understood in comparison to beta cells. Hyperglycemia increases oxidative stress, which induces Akt activation or FoxO activation, depending on cell type. Several studies independently reported that FoxO1 translocations in alpha cells and beta cells were opposite. We compared the responses of pancreatic alpha cells and beta cells against hyperglycemia. Alpha TC-1 cells and Beta TC-6 cells were incubated with control (5mM Glucose) or high glucose (33mM Glucose) with or without PI3K inhibitor or FoxO1 inhibitor. We assessed PI3K, pAkt and phosphorylated FoxO1 (pFoxO1) in both cell lines. Immunostaining of BrdU and FoxO1 was detected by green fluorescence microscopy and confocal microscopy. Hyperglycemia and H2O2 decreased PI3K and pAKT in beta cells, but increased them in alpha cells. FoxO1 localizations and pFoxO1 expressions between alpha cells and beta cells were opposite. Proliferation of beta cells was decreased, but alpha cell proliferation was increased under hyperglycemia. Antioxidant enzymes including superoxide dismutase (SOD) and catalase were increased in beta cells and they were reversed with FoxO1 inhibitor treatment. Increased proliferation in alpha cells under hyperglycemia was attenuated with PI3K inhibitor. In conclusion, hyperglycemia increased alpha cell proliferation and glucagon contents which are opposite to beta cells. These differences may be related to contrasting PI3K/pAkt changes in both cells and subsequent FoxO1 modulation.


Subject(s)
Diabetes Mellitus, Type 2/metabolism , Forkhead Box Protein O1/analysis , Glucagon-Secreting Cells/metabolism , Hyperglycemia/metabolism , Insulin-Secreting Cells/metabolism , Proto-Oncogene Proteins c-akt/analysis , Adenoma , Animals , Cell Line, Tumor , Cell Proliferation/drug effects , Forkhead Box Protein O1/antagonists & inhibitors , Glucagon/analysis , Glucagon-Secreting Cells/chemistry , Glucose/administration & dosage , Glucose/metabolism , Hydrogen Peroxide/pharmacology , Insulin/metabolism , Insulin Secretion , Insulin-Secreting Cells/chemistry , Insulinoma , Mice , Pancreatic Neoplasms , Phosphatidylinositol 3-Kinases/analysis , Phosphoinositide-3 Kinase Inhibitors , Phosphorylation
20.
Sci Rep ; 7(1): 5024, 2017 07 10.
Article in English | MEDLINE | ID: mdl-28694456

ABSTRACT

Single-cell RNA-seq (scRNA-seq) of pancreatic islets have reported on α- and ß-cell gene expression in mice and subjects of predominantly European ancestry. We aimed to assess these findings in East-Asian islet-cells. 448 islet-cells were captured from three East-Asian non-diabetic subjects for scRNA-seq. Hierarchical clustering using pancreatic cell lineage genes was used to assign cells into cell-types. Differentially expressed transcripts between α- and ß-cells were detected using ANOVA and in silico replications of mouse and human islet cell genes were performed. We identified 118 α, 105 ß, 6 δ endocrine cells and 47 exocrine cells. Besides INS and GCG, 26 genes showed differential expression between α- and ß-cells. 10 genes showed concordant expression as reported in rodents, while FAM46A was significantly discordant. Comparing our East-Asian data with data from primarily European subjects, we replicated several genes implicated in nuclear receptor activations, acute phase response pathway, glutaryl-CoA/tryptophan degradations and EIF2/AMPK/mTOR signaling. Additionally, we identified protein ubiquitination to be associated among East-Asian ß-cells. We report on East-Asian α- and ß-cell gene signatures and substantiate several genes/pathways. We identify expression signatures in East-Asian ß-cells that perhaps reflects increased susceptibility to cell-death and warrants future validations to fully appreciate their role in East-Asian diabetes pathogenesis.


Subject(s)
Asian People/genetics , Gene Expression Profiling/methods , Islets of Langerhans/chemistry , Sequence Analysis, RNA/methods , Single-Cell Analysis/methods , Europe , Asia, Eastern , Gene Expression Regulation , Gene Regulatory Networks , Glucagon-Secreting Cells/chemistry , Humans , Insulin-Secreting Cells/chemistry , Male , Organ Specificity , Ubiquitination
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