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Neurog3-Independent Methylation Is the Earliest Detectable Mark Distinguishing Pancreatic Progenitor Identity.
Liu J, Banerjee A, Herring CA, Attalla J, Hu R, Xu Y, Shao Q, Simmons AJ, Dadi PK, Wang S, Jacobson DA, Liu B, Hodges E, Lau KS, Gu G
(2019) Dev Cell 48: 49-63.e7
MeSH Terms: Animals, Basic Helix-Loop-Helix Transcription Factors, Cell Differentiation, Cell Lineage, Endocrine Cells, Homeodomain Proteins, Insulin-Secreting Cells, Islets of Langerhans, Mice, Nerve Tissue Proteins, Organogenesis, Pancreas, Transcription Factors
Show Abstract · Added February 6, 2019
In the developing pancreas, transient Neurog3-expressing progenitors give rise to four major islet cell types: α, β, δ, and γ; when and how the Neurog3 cells choose cell fate is unknown. Using single-cell RNA-seq, trajectory analysis, and combinatorial lineage tracing, we showed here that the Neurog3 cells co-expressing Myt1 (i.e., Myt1Neurog3) were biased toward β cell fate, while those not simultaneously expressing Myt1 (Myt1Neurog3) favored α fate. Myt1 manipulation only marginally affected α versus β cell specification, suggesting Myt1 as a marker but not determinant for islet-cell-type specification. The Myt1Neurog3 cells displayed higher Dnmt1 expression and enhancer methylation at Arx, an α-fate-promoting gene. Inhibiting Dnmts in pancreatic progenitors promoted α cell specification, while Dnmt1 overexpression or Arx enhancer hypermethylation favored β cell production. Moreover, the pancreatic progenitors contained distinct Arx enhancer methylation states without transcriptionally definable sub-populations, a phenotype independent of Neurog3 activity. These data suggest that Neurog3-independent methylation on fate-determining gene enhancers specifies distinct endocrine-cell programs.
Published by Elsevier Inc.
1 Communities
1 Members
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13 MeSH Terms
SIRT2 knockout exacerbates insulin resistance in high fat-fed mice.
Lantier L, Williams AS, Hughey CC, Bracy DP, James FD, Ansari MA, Gius D, Wasserman DH
(2018) PLoS One 13: e0208634
MeSH Terms: Acetylation, Animals, Diet, High-Fat, Energy Metabolism, Insulin, Insulin Resistance, Liver, Male, Mice, Mice, Inbred C57BL, Mice, Knockout, Mitochondria, Muscle, Skeletal, Phosphorylation, Proto-Oncogene Proteins c-akt, Sirtuin 2
Show Abstract · Added January 8, 2019
The NAD+-dependent deacetylase SIRT2 is unique amongst sirtuins as it is effective in the cytosol, as well as the mitochondria. Defining the role of cytosolic acetylation state in specific tissues is difficult since even physiological effects at the whole body level are unknown. We hypothesized that genetic SIRT2 knockout (KO) would lead to impaired insulin action, and that this impairment would be worsened in HF fed mice. Insulin sensitivity was tested using the hyperinsulinemic-euglycemic clamp in SIRT2 KO mice and WT littermates. SIRT2 KO mice exhibited reduced skeletal muscle insulin-induced glucose uptake compared to lean WT mice, and this impairment was exacerbated in HF SIRT2 KO mice. Liver insulin sensitivity was unaffected in lean SIRT2 KO mice. However, the insulin resistance that accompanies HF-feeding was worsened in SIRT2 KO mice. It was notable that the effects of SIRT2 KO were largely disassociated from cytosolic acetylation state, but were closely linked to acetylation state in the mitochondria. SIRT2 KO led to an increase in body weight that was due to increased food intake in HF fed mice. In summary, SIRT2 deletion in vivo reduces muscle insulin sensitivity and contributes to liver insulin resistance by a mechanism that is unrelated to cytosolic acetylation state. Mitochondrial acetylation state and changes in feeding behavior that result in increased body weight correspond to the deleterious effects of SIRT2 KO on insulin action.
2 Communities
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16 MeSH Terms
Role of Bile Acids and GLP-1 in Mediating the Metabolic Improvements of Bariatric Surgery.
Albaugh VL, Banan B, Antoun J, Xiong Y, Guo Y, Ping J, Alikhan M, Clements BA, Abumrad NN, Flynn CR
(2019) Gastroenterology 156: 1041-1051.e4
MeSH Terms: Anastomosis, Surgical, Animals, Anticholesteremic Agents, Bariatric Surgery, Bile Acids and Salts, Blood Glucose, Cholestyramine Resin, Diet, High-Fat, Gallbladder, Glucagon-Like Peptide 1, Glucagon-Like Peptide-1 Receptor, Glucose Tolerance Test, Ileum, Insulin Resistance, Intestines, Lymph, Male, Mice, Mice, Inbred C57BL, Mice, Knockout, Receptors, Cytoplasmic and Nuclear, Receptors, G-Protein-Coupled, Signal Transduction, Verrucomicrobia, Weight Loss
Show Abstract · Added January 4, 2019
BACKGROUND & AIMS - Bile diversion to the ileum (GB-IL) has strikingly similar metabolic and satiating effects to Roux-en-Y gastric bypass (RYGB) in rodent obesity models. The metabolic benefits of these procedures are thought to be mediated by increased bile acids, although parallel changes in body weight and other confounding variables limit this interpretation.
METHODS - Global G protein-coupled bile acid receptor-1 null (Tgr5) and intestinal-specific farnesoid X receptor null (Fxr) mice on high-fat diet as well as wild-type C57BL/6 and glucagon-like polypeptide 1 receptor deficient (Glp-1r) mice on chow diet were characterized following GB-IL.
RESULTS - GB-IL induced weight loss and improved oral glucose tolerance in Tgr5, but not Fxr mice fed a high-fat diet, suggesting a role for intestinal Fxr. GB-IL in wild-type, chow-fed mice prompted weight-independent improvements in glycemia and glucose tolerance secondary to augmented insulin responsiveness. Improvements were concomitant with increased levels of lymphatic GLP-1 in the fasted state and increased levels of intestinal Akkermansia muciniphila. Improvements in fasting glycemia after GB-IL were mitigated with exendin-9, a GLP-1 receptor antagonist, or cholestyramine, a bile acid sequestrant. The glucoregulatory effects of GB-IL were lost in whole-body Glp-1r mice.
CONCLUSIONS - Bile diversion to the ileum improves glucose homeostasis via an intestinal Fxr-Glp-1 axis. Altered intestinal bile acid availability, independent of weight loss, and intestinal Akkermansia muciniphila appear to mediate the metabolic changes observed after bariatric surgery and might be manipulated for treatment of obesity and diabetes.
Copyright © 2019 AGA Institute. Published by Elsevier Inc. All rights reserved.
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25 MeSH Terms
Examining How the MAFB Transcription Factor Affects Islet β-Cell Function Postnatally.
Cyphert HA, Walker EM, Hang Y, Dhawan S, Haliyur R, Bonatakis L, Avrahami D, Brissova M, Kaestner KH, Bhushan A, Powers AC, Stein R
(2019) Diabetes 68: 337-348
MeSH Terms: Animals, Cells, Cultured, Chromatin Immunoprecipitation, Chromosomes, Artificial, Bacterial, DNA Methylation, Female, Humans, In Vitro Techniques, Insulin-Secreting Cells, Maf Transcription Factors, Large, MafB Transcription Factor, Mice, Mice, Transgenic, Pregnancy, Tryptophan Hydroxylase
Show Abstract · Added January 8, 2019
The sustained expression of the MAFB transcription factor in human islet β-cells represents a distinct difference in mice. Moreover, mRNA expression of closely related and islet β-cell-enriched MAFA does not peak in humans until after 9 years of age. We show that the MAFA protein also is weakly produced within the juvenile human islet β-cell population and that expression is postnatally restricted in mouse β-cells by de novo DNA methylation. To gain insight into how MAFB affects human β-cells, we developed a mouse model to ectopically express in adult mouse β-cells using transcriptional control sequences. Coexpression of MafB with MafA had no overt impact on mouse β-cells, suggesting that the human adult β-cell MAFA/MAFB heterodimer is functionally equivalent to the mouse MafA homodimer. However, MafB alone was unable to rescue the islet β-cell defects in a mouse mutant lacking MafA in β-cells. Of note, transgenic production of MafB in β-cells elevated tryptophan hydroxylase 1 mRNA production during pregnancy, which drives the serotonin biosynthesis critical for adaptive maternal β-cell responses. Together, these studies provide novel insight into the role of MAFB in human islet β-cells.
© 2018 by the American Diabetes Association.
1 Communities
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15 MeSH Terms
Pancreatic islet-autonomous insulin and smoothened-mediated signalling modulate identity changes of glucagon α-cells.
Cigliola V, Ghila L, Thorel F, van Gurp L, Baronnier D, Oropeza D, Gupta S, Miyatsuka T, Kaneto H, Magnuson MA, Osipovich AB, Sander M, Wright CEV, Thomas MK, Furuyama K, Chera S, Herrera PL
(2018) Nat Cell Biol 20: 1267-1277
MeSH Terms: Animals, Cell Differentiation, Cell Plasticity, Cell Proliferation, Female, Glucagon-Secreting Cells, Insulin, Insulin-Secreting Cells, Islets of Langerhans, Male, Mice, Inbred C57BL, Mice, Knockout, Mice, SCID, Mice, Transgenic, Signal Transduction, Smoothened Receptor
Show Abstract · Added November 6, 2018
The mechanisms that restrict regeneration and maintain cell identity following injury are poorly characterized in higher vertebrates. Following β-cell loss, 1-2% of the glucagon-producing α-cells spontaneously engage in insulin production in mice. Here we explore the mechanisms inhibiting α-cell plasticity. We show that adaptive α-cell identity changes are constrained by intra-islet insulin- and Smoothened-mediated signalling, among others. The combination of β-cell loss or insulin-signalling inhibition, with Smoothened inactivation in α- or δ-cells, stimulates insulin production in more α-cells. These findings suggest that the removal of constitutive 'brake signals' is crucial to neutralize the refractoriness to adaptive cell-fate changes. It appears that the maintenance of cell identity is an active process mediated by repressive signals, which are released by neighbouring cells and curb an intrinsic trend of differentiated cells to change.
2 Communities
2 Members
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16 MeSH Terms
High CD8 T-Cell Receptor Clonality and Altered CDR3 Properties Are Associated With Elevated Isolevuglandins in Adipose Tissue During Diet-Induced Obesity.
McDonnell WJ, Koethe JR, Mallal SA, Pilkinton MA, Kirabo A, Ameka MK, Cottam MA, Hasty AH, Kennedy AJ
(2018) Diabetes 67: 2361-2376
MeSH Terms: Adipose Tissue, Animals, CD8-Positive T-Lymphocytes, Complementarity Determining Regions, Diet, High-Fat, Glucose Tolerance Test, Insulin Resistance, Liver, Male, Mice, Obesity, Prostaglandins
Show Abstract · Added March 26, 2019
Adipose tissue (AT) CD4 and CD8 T cells contribute to obesity-associated insulin resistance. Prior studies identified conserved T-cell receptor (TCR) chain families in obese AT, but the presence and clonal expansion of specific TCR sequences in obesity has not been assessed. We characterized AT and liver CD8 and CD4 TCR repertoires of mice fed a low-fat diet (LFD) and high-fat diet (HFD) using deep sequencing of the TCRβ chain to quantify clonal expansion, gene usage, and CDR3 sequence. In AT CD8 T cells, HFD reduced TCR diversity, increased the prevalence of public TCR clonotypes, and selected for TCR CDR3 regions enriched in positively charged and less polarized amino acids. Although TCR repertoire alone could distinguish between LFD- and HFD-fed mice, these properties of the CDR3 region of AT CD8 T cells from HFD-fed mice led us to examine the role of negatively charged and nonpolar isolevuglandin (isoLG) adduct-containing antigen-presenting cells within AT. IsoLG-adducted protein species were significantly higher in AT macrophages of HFD-fed mice; isoLGs were elevated in M2-polarized macrophages, promoting CD8 T-cell activation. Our findings demonstrate that clonal TCR expansion that favors positively charged CDR3s accompanies HFD-induced obesity, which may be an antigen-driven response to isoLG accumulation in macrophages.
© 2018 by the American Diabetes Association.
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MeSH Terms
Molecular and epidemiologic characterization of Wilms tumor from Baghdad, Iraq.
Phelps HM, Al-Jadiry MF, Corbitt NM, Pierce JM, Li B, Wei Q, Flores RR, Correa H, Uccini S, Frangoul H, Alsaadawi AR, Al-Badri SAF, Al-Darraji AF, Al-Saeed RM, Al-Hadad SA, Lovvorn Iii HN
(2018) World J Pediatr 14: 585-593
MeSH Terms: Adaptor Proteins, Signal Transducing, Child, Preschool, DNA Topoisomerases, Type II, Female, Homeodomain Proteins, Humans, Immunohistochemistry, Infant, Insulin-Like Growth Factor II, Iraq, Kidney Neoplasms, Male, Multiplex Polymerase Chain Reaction, Mutation, N-Myc Proto-Oncogene Protein, Nerve Tissue Proteins, Neural Cell Adhesion Molecules, Nuclear Proteins, Poly-ADP-Ribose Binding Proteins, Receptors, Retinoic Acid, Sequence Analysis, DNA, Transcription Factors, Tumor Suppressor Protein p53, Tumor Suppressor Proteins, WT1 Proteins, Wilms Tumor, beta Catenin
Show Abstract · Added January 28, 2019
BACKGROUND - Wilms tumor (WT) is the most common childhood kidney cancer worldwide, yet its incidence and clinical behavior vary according to race and access to adequate healthcare resources. To guide and streamline therapy in the war-torn and resource-constrained city of Baghdad, Iraq, we conducted a first-ever molecular analysis of 20 WT specimens to characterize the biological features of this lethal disease within this challenged population.
METHODS - Next-generation sequencing of ten target genes associated with WT development and treatment resistance (WT1, CTNNB1, WTX, IGF2, CITED1, SIX2, p53, N-MYC, CRABP2, and TOP2A) was completed. Immunohistochemistry was performed for 6 marker proteins of WT (WT1, CTNNB1, NCAM, CITED1, SIX2, and p53). Patient outcomes were compiled.
RESULTS - Mutations were detected in previously described WT "hot spots" (e.g., WT1 and CTNNB1) as well as novel loci that may be unique to the Iraqi population. Immunohistochemistry showed expression domains most typical of blastemal-predominant WT. Remarkably, despite the challenges facing families and care providers, only one child, with combined WT1 and CTNNB1 mutations, was confirmed dead from disease. Median clinical follow-up was 40.5 months (range 6-78 months).
CONCLUSIONS - These data suggest that WT biology within a population of Iraqi children manifests features both similar to and unique from disease variants in other regions of the world. These observations will help to risk stratify WT patients living in this difficult environment to more or less intensive therapies and to focus treatment on cell-specific targets.
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27 MeSH Terms
Identical and Nonidentical Twins: Risk and Factors Involved in Development of Islet Autoimmunity and Type 1 Diabetes.
Triolo TM, Fouts A, Pyle L, Yu L, Gottlieb PA, Steck AK, Type 1 Diabetes TrialNet Study Group
(2019) Diabetes Care 42: 192-199
MeSH Terms: Adolescent, Adult, Autoantibodies, Autoimmunity, Child, Child, Preschool, Diabetes Mellitus, Type 1, Disease Progression, Diseases in Twins, Environment, Female, Genetic Predisposition to Disease, Glutamate Decarboxylase, Humans, Insulin, Islets of Langerhans, Male, Mass Screening, Risk Factors, Seroepidemiologic Studies, Siblings, Twins, Twins, Dizygotic, Twins, Monozygotic, Young Adult
Show Abstract · Added August 15, 2018
OBJECTIVE - There are variable reports of risk of concordance for progression to islet autoantibodies and type 1 diabetes in identical twins after one twin is diagnosed. We examined development of positive autoantibodies and type 1 diabetes and the effects of genetic factors and common environment on autoantibody positivity in identical twins, nonidentical twins, and full siblings.
RESEARCH DESIGN AND METHODS - Subjects from the TrialNet Pathway to Prevention Study ( = 48,026) were screened from 2004 to 2015 for islet autoantibodies (GAD antibody [GADA], insulinoma-associated antigen 2 [IA-2A], and autoantibodies against insulin [IAA]). Of these subjects, 17,226 (157 identical twins, 283 nonidentical twins, and 16,786 full siblings) were followed for autoantibody positivity or type 1 diabetes for a median of 2.1 years.
RESULTS - At screening, identical twins were more likely to have positive GADA, IA-2A, and IAA than nonidentical twins or full siblings (all < 0.0001). Younger age, male sex, and genetic factors were significant factors for expression of IA-2A, IAA, one or more positive autoantibodies, and two or more positive autoantibodies (all ≤ 0.03). Initially autoantibody-positive identical twins had a 69% risk of diabetes by 3 years compared with 1.5% for initially autoantibody-negative identical twins. In nonidentical twins, type 1 diabetes risk by 3 years was 72% for initially multiple autoantibody-positive, 13% for single autoantibody-positive, and 0% for initially autoantibody-negative nonidentical twins. Full siblings had a 3-year type 1 diabetes risk of 47% for multiple autoantibody-positive, 12% for single autoantibody-positive, and 0.5% for initially autoantibody-negative subjects.
CONCLUSIONS - Risk of type 1 diabetes at 3 years is high for initially multiple and single autoantibody-positive identical twins and multiple autoantibody-positive nonidentical twins. Genetic predisposition, age, and male sex are significant risk factors for development of positive autoantibodies in twins.
© 2018 by the American Diabetes Association.
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25 MeSH Terms
Low-Dose Anti-Thymocyte Globulin (ATG) Preserves β-Cell Function and Improves HbA in New-Onset Type 1 Diabetes.
Haller MJ, Schatz DA, Skyler JS, Krischer JP, Bundy BN, Miller JL, Atkinson MA, Becker DJ, Baidal D, DiMeglio LA, Gitelman SE, Goland R, Gottlieb PA, Herold KC, Marks JB, Moran A, Rodriguez H, Russell W, Wilson DM, Greenbaum CJ, Type 1 Diabetes TrialNet ATG-GCSF Study Group
(2018) Diabetes Care 41: 1917-1925
MeSH Terms: Adolescent, Adult, Antilymphocyte Serum, C-Peptide, Child, Cytoprotection, Diabetes Mellitus, Type 1, Dose-Response Relationship, Drug, Double-Blind Method, Drug Therapy, Combination, Female, Glycated Hemoglobin A, Granulocyte Colony-Stimulating Factor, Humans, Insulin-Secreting Cells, Male, Pilot Projects, Polyethylene Glycols, Recombinant Proteins, Young Adult
Show Abstract · Added May 2, 2019
OBJECTIVE - A pilot study suggested that combination therapy with low-dose anti-thymocyte globulin (ATG) and pegylated granulocyte colony-stimulating factor (GCSF) preserves C-peptide in established type 1 diabetes (T1D) (duration 4 months to 2 years). We hypothesized that ) low-dose ATG/GCSF or ) low-dose ATG alone would slow the decline of β-cell function in patients with new-onset T1D (duration <100 days).
RESEARCH DESIGN AND METHODS - A three-arm, randomized, double-masked, placebo-controlled trial was performed by the Type 1 Diabetes TrialNet Study Group in 89 subjects: 29 subjects randomized to ATG (2.5 mg/kg intravenously) followed by pegylated GCSF (6 mg subcutaneously every 2 weeks for 6 doses), 29 to ATG alone (2.5 mg/kg), and 31 to placebo. The primary end point was mean area under the curve (AUC) C-peptide during a 2-h mixed-meal tolerance test 1 year after initiation of therapy. Significance was defined as one-sided value < 0.025.
RESULTS - The 1-year mean AUC C-peptide was significantly higher in subjects treated with ATG (0.646 nmol/L) versus placebo (0.406 nmol/L) ( = 0.0003) but not in those treated with ATG/GCSF (0.528 nmol/L) versus placebo ( = 0.031). HbA was significantly reduced at 1 year in subjects treated with ATG and ATG/GCSF, = 0.002 and 0.011, respectively.
CONCLUSIONS - Low-dose ATG slowed decline of C-peptide and reduced HbA in new-onset T1D. Addition of GCSF did not enhance C-peptide preservation afforded by low-dose ATG. Future studies should be considered to determine whether low-dose ATG alone or in combination with other agents may prevent or delay the onset of the disease.
© 2018 by the American Diabetes Association.
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MeSH Terms
Acute Nitric Oxide Synthase Inhibition Accelerates Transendothelial Insulin Efflux In Vivo.
Williams IM, McClatchey PM, Bracy DP, Valenzuela FA, Wasserman DH
(2018) Diabetes 67: 1962-1975
MeSH Terms: Animals, Biological Transport, Blood Pressure, Blotting, Western, Glucose, Insulin, Male, Mice, Inbred C57BL, NG-Nitroarginine Methyl Ester, Nitric Oxide, Nitric Oxide Synthase, Transendothelial and Transepithelial Migration
Show Abstract · Added March 26, 2019
Before insulin can stimulate glucose uptake in muscle, it must be delivered to skeletal muscle (SkM) through the microvasculature. Insulin delivery is determined by SkM perfusion and the rate of movement of insulin across the capillary endothelium. The endothelium therefore plays a central role in regulating insulin access to SkM. Nitric oxide (NO) is a key regulator of endothelial function and stimulates arterial vasodilation, which increases SkM perfusion and the capillary surface area available for insulin exchange. The effects of NO on transendothelial insulin efflux (TIE), however, are unknown. We hypothesized that acute reduction of endothelial NO would reduce TIE. However, intravital imaging of TIE in mice revealed that reduction of NO by l--nitro-l-arginine methyl ester (l-NAME) enhanced the rate of TIE by ∼30% and increased total extravascular insulin delivery. This accelerated TIE was associated with more rapid insulin-stimulated glucose lowering. Sodium nitroprusside, an NO donor, had no effect on TIE in mice. The effects of l-NAME on TIE were not due to changes in blood pressure alone, as a direct-acting vasoconstrictor (phenylephrine) did not affect TIE. These results demonstrate that acute NO synthase inhibition increases the permeability of capillaries to insulin, leading to an increase in delivery of insulin to SkM.
© 2018 by the American Diabetes Association.
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MeSH Terms