bluuebunny/crossref_metadata_2025 huggingface dataset:
Iron Overload Plays an Important Role in ER Stress-Induced Insulin Resistance in Human Skeletal Muscle Cells
Authors: LEE KWANWOO , CUI RIHUA , KIM DAE JUNG , CHOI SUNGE , LEE WHA JOUNG , KANG YUP , KIM TAE HO , MOON HYUN UK , JEON JA YOUNG , HAN SEUNG JIN , KIM HAE JIN
Published: June 2018

Aim: In this study, we investigated the relationship and molecular mechanisms between iron-overload and ER-stress-induced insulin resistance in human skeletal muscle cells.

Methods: Intracellular iron was measured using calcein AM. Iron metabolism-related genes were analyzed by immunoblotting and PCR. The study was conducted using iron supplementation, which was achieved by palmitate, FeSO4 and FeCl3 administration, and iron reduction, which occurred by DFO, DS and Bapta AM administration, and knockdown of tfR1 or IRP2 genes, to investigate the effects of iron metabolism on insulin sensitivity in HSMMs. Intracellular calcium was detected using Fluo-3/AM staining. TfR1 internalization regulated by calcium was detected by GFP-labelled transferrin.

Results: Endoplasmic reticulum stress by tunicamycin, thapsigargin, or palmitate evoked insulin resistance and simultaneously increased intracellular iron. Iron chelator, DFO, dramatically prevented ER-stress inducer-induced insulin resistance and iron donor impaired insulin sensitivity in vitro and in vivo through activation of JNK. Among several iron metabolism-related genes, tfR1 plays a predominant role for maintaining iron homeostasis in HSMMs. Treatment of ER-stress inducer positively regulated translocation of tfR1 by intracellular calcium, but protein levels of tfR1 did not change. Iron reduction, by adding iron chelator, calcium chelator, or knockdown of tfR1 or IRP2, dramatically prevented ER-stress-induced insulin resistance through the reduction of iron-overload.

Conclusions/Interpretation: The current study shows ER-stress inducer evoked insulin resistance through iron overload. Reduction of intracellular iron, by iron chelator, significantly prevents insulin resistance. Therefore, attempts to block iron overload might be a strategy for preventing insulin resistance and diabetes.

Disclosure

K. Lee: None. R. Cui: None. D. Kim: None. S. Choi: None. W. Lee: None. Y. Kang: None. T. Kim: None. H. Moon: None. J. Jeon: None. S. Han: None. H. Kim: None.
The Mediterranean Diet and Two-Year Changes in Cognitive Function in Puerto Rican Adults With vs. Without Type 2 Diabetes
Authors: MATTEI JOSIEMER , BIGORNIA SHERMAN J. , SOTOS-PRIETO MERCEDES , SCOTT TAMMY , GAO XIANG , TUCKER KATHERINE L.
Published: June 2018

People with type 2 diabetes (T2D), especially uncontrolled T2D, have high risk of cognitive decline. The role of a Mediterranean diet on cognitive function has not been assessed for adults with vs. without T2D within the same population. We aimed to determine associations of a Mediterranean diet score (MeDS) with 2 year changes in cognitive function by T2D status and by glycemic control status. We used data from the Boston Puerto Rican Health Study (mean (SD) age= 57.2 (7.6) y; n=711 without T2D; n=465 with T2D defined as fasting plasma glucose ≥ 126 mg/dL or medication use). Glycemic control at baseline was categorized as uncontrolled (hemoglobin A1c ≥7%; 74% of T2D sample)) vs. controlled (26%). Two-y changes in glycemic control were defined as stable/improved (32%) vs. poor/declined (68%). Baseline MeDS ranged from 0-9 by scoring participants within the sex-specific healthy median intake of 9 foods and nutrients. The primary outcome was 2 year change in global cognitive function z-score, which included 7 cognitive tests. Adjusting for baseline sociodemographic and lifestyle factors, comorbidities, and baseline measure, MeDS was positively associated with 2 year change in global cognitive function in adults with T2D (β ± SE=0.027 ± 0.011; p=0.016) but not without T2D (-0.002 ± 0.008; p=0.80). Similar results were noted for single cognitive tests (i.e., mini-mental state examination, word recognition, digit span, clock drawing). Better global cognitive function over 2 years with higher MeDS was noted with glycemic control at baseline (0.062 ± 0.020; p=0.004) or stable/improved over 2 years (0.053 ± 0.019; p=0.007), but not for uncontrolled or poor/declined glycemic control. Adhering to a Mediterranean diet is associated with positive 2 year changes in cognitive function among adults with T2D. Glycemic control further sustains these benefits, suggesting that both a healthy Mediterranean diet and effective clinical management may help preserve optimal cognitive function in adults with T2D.

Disclosure

J. Mattei: None. S.J. Bigornia: None. M. Sotos-Prieto: None. T. Scott: None. X. Gao: None. K.L. Tucker: None.
Effects of Hyperglycemia on Skeletal Muscle Glucose Metabolism in Healthy Subjects
Authors: SHANNON CHRIS , MEROVCI AURORA , TRIPATHY DEVJIT , ABDUL-GHANI MUHAMMAD , NORTON LUKE , DEFRONZO RALPH A.
Published: June 2018

Background: Physiological hyperglycemia can induce skeletal muscle insulin resistance and alterations in metabolic glucose partitioning. We investigated the mechanisms driving this muscle glucotoxicity in response to a three day elevation of plasma glucose concentrations.

Methods: Twenty-five lean, glucose tolerant subjects (mean ± SD age 46 ± 4 years; BMI 25 ± 1 kg/m2) underwent a euglycemic insulin clamp (80 mU/m2·min) at baseline and following three days of saline (n=5) or glucose (n=20) infusion to raise plasma glucose by 45 mg/dL. Oxidative (GOX), non-oxidative (NOGD) and total (TGD) glucose disposal were calculated from indirect calorimetry and glucose infusion rate. Skeletal muscle biopsies were obtained prior to and after each clamp for the determination of metabolite concentrations, protein phosphorylation and pyruvate dehydrogenase (PDH) activation status (PDHa). Data are presented as mean ± SE and were analyzed using two-way ANOVA.

Results: Three days of glucose infusion increased basal (1.2 ± 0.1 vs. 4.3 ± 0.3) and insulin-stimulated (2.3 ± 0.2 vs. 4.8 ± 0.3 mg/kg/min) GOX by 3.5 and 2.2-fold, respectively (P<0.001), whereas NOGD was 51% lower (9.2 ± 2.6 vs. 4.5 ± 2.1 mg/kg/min; P<0.001), resulting in a 16% reduction in TGD (10.3 ± 2.4 vs. 8.7 ± 2.1 mg/kg/min; P<0.01). Muscle glycogen content was doubled (343 ± 18 vs. 759 ± 47 mmol/kg dry weight; P<0.001) and glycogen synthase phosphorylation (Ser641) was increased by 46% (P=0.03), whilst GSK3β phosphorylation (Ser9) tended to be reduced (P=0.07). Glucose infusion also reduced insulin-stimulated PDHa by 20% (P=0.02) and Akt phosphorylation (Ser473) by 27% (P=0.03). No changes were observed in the saline group.

Conclusion: Hyperglycemia caused a robust increase in basal GOX, such that further insulin-stimulated activation of GOX (distal insulin signaling and PDH) was impaired. Deficits in NOGD, and subsequently, TGD likely occur as a consequence of perturbed glycogen synthase activation in the face of augmented muscle glycogen concentrations.

Disclosure

C. Shannon: None. A. Merovci: None. D. Tripathy: None. M. Abdul-Ghani: None. L. Norton: None. R.A. DeFronzo: Speaker's Bureau; Self; AstraZeneca, Novo Nordisk Inc.. Advisory Panel; Self; AstraZeneca, Novo Nordisk Inc., Janssen Pharmaceuticals, Inc., Boehringer Ingelheim Pharmaceuticals, Inc., Elcelyx Therapeutics, Inc., Intarcia Therapeutics, Inc.. Research Support; Self; AstraZeneca, Boehringer Ingelheim Pharmaceuticals, Inc., Janssen Pharmaceuticals, Inc., Takeda Pharmaceuticals U.S.A., Inc..
Prdx6 Prevents Diabetic Myopathy by Improving Skeletal Muscle Cell Differentiation
Authors: PACIFICI FRANCESCA , CAPUANI BARBARA , PIERMARINI FRANCESCA , PASTORE DONATELLA , ARRIGA ROBERTO , COPPOLA ANDREA , REA SILVIA , DONADEL GIULIA , BELLIA ALFONSO , DELLA-MORTE DAVID , LAURO DAVIDE
Published: June 2018

Diabetes mellitus is characterized by a state of hyperglycemia resulting from altered insulin secretion by pancreatic beta cell, insulin action or both. This pathological condition is frequently associated with muscle mass loss, a condition defined as sarcopenia, and diabetic myopathy, represented by an impairment of the regenerative power of muscle fiber and by an altered differentiation of progenitor cells. Oxidative stress has been identified as the main cause of muscular alterations typical of diabetic patients. We showed that Peroxiredoxin 6 (Prdx6), a relatively new antioxidant enzyme belonging from the Peroxiredoxin family, has a central role in glucose homeostasis by exerting a potent antioxidant role. Based on these results, in the present study we aimed to verify whether Prdx6 modulates the association between diabetes and the progression of myopathy and sarcopenia. Firstly, we evaluated the gene expression of the main factors involved in the differentiation of myogenic muscle cells such as MyoD and Myogenin in murine knockout models for Prdx6 (Prdx6-/-). We observed significant decreased levels of both genes in Prdx6-/- mice compared to controls, suggesting an impairment of the regenerative potential of muscle fibers. These data were, also, confirmed by using in vitro cell model of murine myoblasts (C2C7) knockdown for Prdx6. Moreover, in the murine models, the process of muscle atrophy was studied by evaluating the gene expression of MuRF1 and Atrogin-1 that finely regulate protein degradation at skeletal muscle level. According to our hypothesis, the expression levels of both enzymes were significantly increased confirming the presence of muscle atrophy. Our study, for the first time, highlights a fundamental role of Prdx6 in the preservation of muscle mass, suggesting how Prdx6 can be considered a potential therapeutic target for diabetic myopathy and sarcopenia. However, further studies are needed in order to understand the molecular mechanism underlying this phenomenon.

Disclosure

F. Pacifici: None. B. Capuani: None. F. Piermarini: None. D. Pastore: None. R. Arriga: None. A. Coppola: None. S. Rea: None. G. Donadel: None. A. Bellia: None. D. Della-Morte: None. D. Lauro: None.
Transient Activation of Skeletal Muscle Rac1 in Obesity-Related Insulin Resistance
Authors: STIERWALT HARRISON D. , BERGMAN BRYAN , EHRLICHER SARAH E. , ROBINSON MATTHEW M. , NEWSOM SEAN A.
Published: June 2018

Rac1 is required for normal insulin-stimulated glucose transport in skeletal muscle and may be negatively regulated by lipids. We investigated if insulin stimulation of Rac1 was impaired with the accumulation of lipids in skeletal muscle, serving as a mechanism of insulin resistance with obesity. Male C57BL/6J mice consumed a 60% high-fat diet (HFD) for 12 weeks to induce obesity compared with low-fat diet (LFD). Insulin sensitivity and signaling were assessed using hyperinsulinemic-euglycemic (INS) or saline (CON) clamps (n=7-10 per diet/clamp). Rac1 activation and other insulin signaling was measured in quadriceps muscle harvested following the clamp conditions. Muscle lipids were assessed via liquid chromatography, tandem mass spectrometry. Activation of Rac1 (via GTP binding) was not increased in INS compared with CON conditions (P = 0.60) in either LFD or HFD. Further, insulin-stimulated pAktSer473 was similar between groups (P = 0.90) despite HFD mice having greater fat mass (P < 0.01), lower glucose infusion rates during a 2-hour INS clamp (P < 0.02), and greater skeletal muscle lipid content, including total ceramide (P = 0.03) and numerous 1,2 diacylglycerols (P < 0.05). We considered if Rac1 activation is transient since Rac1 activity was not changed after the 2-hour INS condition. Time-course experiments in cultured L6 myotubes revealed that 2-min of insulin stimulation was sufficient to increase Rac1-GTP binding (P < 0.01 vs. basal) and activation returned to basal by 10-min (P = 0.23 vs. basal). Modeling insulin resistance using overnight fatty acid treatments did not alter insulin-stimulated Rac1-GTP binding compared with no fatty acid control cells (P = 0.44).

In summary, skeletal muscle Rac1 activation by insulin is transient, but may be a key determinant of impaired glucose uptake with obesity in mice given the lack of impairment in Akt activation. In contrast, overnight fatty acid incubation was not sufficient to inhibit activation of Rac1 by insulin in L6 myotubes.

Disclosure

H.D. Stierwalt: None. B. Bergman: Research Support; Self; Eli Lilly and Company. Advisory Panel; Spouse/Partner; Novo Nordisk Inc., Merck & Co., Inc., AstraZeneca, Boehringer Ingelheim Pharmaceuticals, Inc., Eli Lilly and Company. S.E. Ehrlicher: None. M.M. Robinson: None. S.A. Newsom: None.
Skeletal Muscle Mitochondrial Fission Is Increased after an Overnight Lipid Infusion in Healthy Humans
Authors: FEALY CIARAN E. , AXELROD CHRISTOPHER L. , ERICKSON MELISSA L. , HUANG EMILY , HARI ADITHYA , MULYA ANNY , FUJIOKA HISASHI , HOPPEL CHARLES L. , KIRWAN JOHN P.
Published: June 2018

The role of mitochondria in insulin resistance and type 2 diabetes (T2D) is the subject of much debate. Recent evidence has suggested the presence of altered skeletal muscle mitochondrial dynamics, both increased fission and reduced fusion, in the etiology of insulin resistance and T2D, however, it is unclear what role, if any, changes in mitochondrial dynamics play in the induction of insulin resistance. We have proposed that increased mitochondrial fission may represent an early mechanistic link between the mitochondria and the onset of skeletal muscle insulin resistance. To test this hypothesis we recruited healthy humans to receive, in a randomized crossover design, an overnight saline (control) or lipid infusion (20% Intralipid) at 0.55 ml/kg/h, followed by a 2h, 90 mg/dL, 40 mU/m2 hyperinsulinemic-euglycemic clamp to assess insulin sensitivity. Changes to mitochondrial dynamics protein expression were assessed by western blot, ex vivo mitochondrial membrane potential (TMRM staining) by confocal microscopy, oxidative capacity by respirometry (Oroboros O2k), and mitochondrial morphology by transmission electron microscopy, in skeletal muscle biopsy samples following the overnight infusions. Preliminary data (n=8; 5M, 3F; Age: 26±1 years; BMI: 22.6±0.7; VO2max: 44.0±2.5) indicate that lipid infusion results in a tendency for reduced insulin sensitivity (P=0.08) and mitochondrial membrane potential (P=0.09), and an increase in Complex I state 3 respiration (P<0.05). Dynamin related protein 1 (Drp1) activation (P<0.05) by phosphorylation at serine 616—a key step in mitochondrial fission, and the Drp1 adaptor protein MiD49 (P=0.10) were increased after lipid infusion. No changes to mitochondrial fusion (Mfn1, Mfn2, OPA1), or mitophagy (Pink1, Parkin) proteins were observed following the lipid infusion. These data support our hypothesis that increased mitochondrial fission is an early adaptation to lipid induced insulin resistance in healthy humans.

Disclosure

C.E. Fealy: None. C.L. Axelrod: None. M.L. Erickson: None. E. Huang: None. A. Hari: None. A. Mulya: None. H. Fujioka: None. C.L. Hoppel: None. J.P. Kirwan: None.
Circulating Pigment Epithelium-Derived–Factor Levels—Hyperglycemia vs. Insulin Resistance
Authors: MASER RAELENE E. , LENHARD JAMES , POHLIG RYAN , BABU BALAGOPAL P.
Published: June 2018

Serum pigment epithelium-derived factor (PEDF) levels are correlated with adiposity, dyslipidemia, and renal dysfunction in type 2 diabetes (T2D) men. Major sources of circulating PEDF include the liver and adipose tissue. Cross-sectional studies have reported higher serum PEDF levels in T2D vs. controls. Although studies have suggested PEDF’s role in mediating insulin resistance, its potential role with regard to glycemic control remains unclear. We examined the association of serum PEDF and glycemic control in individuals with T2D (n=50; 21 men/29 women; age=63±10 years; CKD1.8; n=23; p<0.05). Spearman rank correlations of PEDF included: HbA1c≥7% (r=0.27, p=0.059), HOMA-IR>1.8 (r=0.30, p=0.037), triglycerides (r=0.53, p<0.001), creatinine (r=0.51, p<0.001), and AST (r=0.33, p=0.02). Linear regression, with PEDF as the dependent variable, revealed that AST (p=0.003), creatinine (p=0.001), triglycerides (p<0.001), and poor glycemic control (HbA1c≥7%) (p=0.009) were significant correlates (model R2=0.63, p<0.001); whereas insulin resistance (HOMA-IR>1.8) was not (p=0.70). There was also a significant interaction of AST x creatinine (p=0.02). While some suggest that elevated PEDF levels are associated with insulin resistance, the lack of an association in our data is intriguing. It is possible that gluconeogenesis by the liver and kidney is associated with elevation in circulating PEDF and PEDF may be part of an incomplete self-defensive regulatory mechanism to limit hyperglycemia. The significant interaction suggests that the relationship between creatinine and PEDF depends on AST. Taken together, the association between PEDF and poor glycemic control in persons with T2D may suggest a preferentially protective compensatory response of PEDF against hyperglycemia but not insulin resistance.

Disclosure

R.E. Maser: None. J. Lenhard: Speaker's Bureau; Self; Eli Lilly and Company, Janssen Pharmaceuticals, Inc., Sanofi. R. Pohlig: None. P. Balagopal: None.
Comparative Study on Glucose Metabolism Before and After Surgery in Patients with Adrenal Cushing's Syndrome
Authors: MIYOSHI KENGO , TSURUTANI YUYA , SUZUKI AKIHIKO , TAKIGUCHI TOMOKO , SUGISAWA CHIHO , SAITO JUN , NISHIKAWA TETSUO
Published: June 2018

Adrenal Cushing’s syndrome (CS) is caused by cortisol-producing adrenal adenoma (CPA) and is frequently accompanied with impaired glucose tolerance (IGT) or diabetes mellitus (DM). Previous cross-sectional studies showed that glucose metabolism disorders in CS are characterized by insulin resistance and insufficient β-cell compensation. However, because of the rarity of CS, there are few studies that assessed whether glucose metabolism disorders could be ameliorated by surgical treatment. We evaluated the changes in glucose metabolism before and after surgery for CPA. The participants were 11 (10 female and 1 male) patients with overt adrenal CS, treated with unilateral adrenalectomy for CPA between 20and 2017. Patients with pre-diagnosed DM were excluded. A 75 g oral glucose tolerance test (OGTT) was performed before and after surgery. Using the data from OGTT, insulin resistance and insulin secretion indices were calculated. After surgery, cortisol secretion and body mass index decreased significantly (24 h urinary free cortisol: 582 [321-743] to 31.3 [23.6-40.6] μg/day, p = 0.001, and 25.8 [20.6-26.2] to 21.4 [19.6-24.2], p = 0.0077, respectively). The type of OGTT was largely improved (normal glucose tolerance/IGT/DM: 2/8/1 to 8/3/0). The immunoreactive insulin and glucose levels during the OGTT decreased significantly. The homeostatic model assessment of insulin resistance decreased significantly (2.4 [1.4-2.8] to 1.0 [0.6-1.1], p = 0.002), and the Matsuda index increased significantly (3.0 [2.3-4.5] to 8.2 [6.3-11.4], p < 0.001). In addition, the insulinogenic and disposition indices increased significantly (0.70 [0.22-1.51] to 1.22 [0.78-1.64], p = 0.04, and 609.1 [237.8-1095.2] to 1286.0 [1034.6-1857.6], p = 0.001, respectively).

In conclusion, our study showed that insulin resistance and insulin secretion were largely ameliorated after surgery for CPA, indicating that β cell dysfunction caused by cortisol overproduction is reversible.

Disclosure

K. Miyoshi: None. Y. Tsurutani: Research Support; Self; Astellas Pharma US, Inc.. Speaker's Bureau; Self; Astellas Pharma US, Inc., Amgen Inc., AstraZeneca, Boehringer Ingelheim Pharmaceuticals, Inc., Daiichi Sankyo Company, Limited, Eli Lilly and Company, Merck Sharp & Dohme Corp., Kissei Pharmaceutical Co., Ltd., Kowa Pharmaceuticals America, Inc., Kyowa Hakko Kirin Co., Ltd., Mitsubishi Tanabe Pharma Corporation, Mochida Pharmaceutical Co., Ltd., Novartis Pharmaceuticals Corporation, Novo Nordisk Inc., Ono Pharmaceutical Co., Ltd., Sanofi, Sumitomo Dainippon Pharma Co., Ltd., Takeda. A. Suzuki: None. T. Takiguchi: None. C. Sugisawa: None. J. Saito: None. T. Nishikawa: None.
The Influence of Metabolic Surgery and Endoscopy on Serum Proteome in Subjects with Obesity and Type 2 Diabetes Mellitus
Authors: MRAZ MILOS , HARANT KAREL , KRATOCHVILOVA HELENA , CINKAJZLOVA ANNA , KLOUCKOVA JANA , KAVÁLKOVÁ PETRA , LACINOVÁ ZDENA , BENES MAREK , VLASAKOVA ZUZANA , DOLEZALOVA KARIN , FRIED MARTIN , PELIKANOVA TEREZIE , HALUZIK MARTIN
Published: June 2018

Metabolic surgery and endoscopy are associated with long-term reduction in body weight and amelioration of glucose control; however, exact mechanisms responsible for these effects remain unclear. We performed a complex serum proteomic analysis in obese subjects with type 2 diabetes mellitus undergoing endoscopic duodenal-jejunal by-pass liner implantation (DJBL) or gastric plication (GP) to identify potential factors involved in postprocedural metabolic improvements. Thirty-one obese diabetic subject - 20 undergoing DJBL implantation and 11 GP - were examined at baseline and 10 months after DJBL or 6 months after GP, respectively. Serum proteomic analysis was performed using LC-MS (liquid chromatography-mass spectrometry) and the results were compared with human Uniprot reference database. Both procedures resulted in reduction in body weight (BMI 41.5 ± 1.0 vs. 37.6 ± 1.0 kg/m2, p=0.01 for DJBL and 41.6 ± 1.1 vs. 35.4 ± 1.2 kg/m2, p<0.001 for GP) and HbA1C (72.5 ± 4.3 vs. 53.9 ± 3.3 mmol/mol, p=0.002 for DJBL and 55.4 ± 4.1 vs. 45.3 ± 2.3 mmol/mol, p=0.046 for GP). Proteomic analysis involving 600+ proteins revealed a significant change in 27 proteins after DJBL, including increase in IGFBP2, lyzosyme C and the islet cells regeneration factor lithostatine-1-α and decrease in C1q and serum amyloid A4. GP was associated with a change in 13 proteins including elevation of paraoxonase 1 and reduction of matrix metalloproteinase 2. To conclude, despite better weight-reducing efficacy of GP DJBL had a more profound effect on serum proteome, which might at least partially explain the stronger reduction in HbA1C observed in DJBL.

Disclosure

M. Mraz: None. K. Harant: None. H. Kratochvilova: None. A. Cinkajzlova: None. J. Klouckova: None. P. Kaválková: None. Z. Lacinová: None. M. Benes: None. Z. Vlasakova: None. K. Dolezalova: None. M. Fried: None. T. Pelikanova: None. M. Haluzik: None.
The Preprohormone Expression Profile of Enteroendocrine Cells following Roux-en-Y Gastric Bypass in Rats
Authors: RUDKJAER LISE BIEHL , ZHANG CHEN , RIGBOLT KRISTOFFER , PEDERSEN SØREN L. , FALKENHAHN MECHTHILDE , HÜBSCHLE THOMAS , SCHMIDT THORSTEN , VRANG NIELS , JELSING JACOB
Published: June 2018

It is well-known that Roux-en-Y gastric bypass (RYGB) leads to a rapid remission of type 2 diabetes and a marked and long-term body weight loss, but the molecular mechanisms driving these desirable effects are not fully understood. RYGB results in increased plasma levels of several gut peptidergic hormones with either anorexigenic and/or antidiabetic effects. However, the potent effects of RYGB cannot solely be ascribed to these, and it is therefore likely that additional factors play a role.

To gain further insight we have characterized the mRNA expression profile in enteroendocrine cells in the gut at day 9, 22 and 60 following surgery in a RYGB rat model. The enteroendocrine cells were identified by chromogranin-A immunohistochemistry staining, and isolated by laser capture microdissection from five locations covering the full rostrocaudal extent of the gastrointestinal tract. The mRNA expression profiles were analyzed by RNAseq, and bioinformatic analyses were applied to identify known and predicted preprohormones differentially regulated following RYGB. In total 64 putative preprohormones were identified in the secretome of rat enteroendocrine cells, of which 40 were shown to be differentially regulated at one or more time-points post surgery, including several well-known preprohormone genes (GCG, CCK, GHRL, GIP, NMU, SCT, NPY, and VIP). Only six preprohormones were differentially regulated at all time-points (NMU, TAC3, FAM3D, SCT1, SCT and ADM).

We present the full mRNA expression profile of the secretome of chromogranin A positive enteroendocrine cells following RYGB surgery in rats. The data provides a region-specific characterization of all preprohormone encoding genes in the rat gut, including 23 not hitherto known. This comprehensive catalogue of gut peptide hormone expression might help our understanding of hormone mediated effects of RYGB on diabetes remission and body weight lowering.

Disclosure

L. Biehl Rudkjaer: Employee; Self; Gubra. C. Zhang: Employee; Self; Gubra. Stock/Shareholder; Self; Gubra. K. Rigbolt: Employee; Self; Gubra. Stock/Shareholder; Self; Gubra. S.L. Pedersen: None. M. Falkenhahn: None. T. Hübschle: Employee; Self; Sanofi-Aventis Deutschland GmbH. T. Schmidt: None. N. Vrang: Board Member; Self; Gubra. Employee; Self; Gubra. Stock/Shareholder; Self; Gubra. J. Jelsing: Stock/Shareholder; Self; Gubra. Research Support; Self; Sanofi.
Discover and Track Obesity Relevant Research Resources Using dkNET (NIDDK Information Network)
Authors: LIN KO-WEI , BANDROWSKI ANITA , GO JAMES , OZYURT IBRAHIM BURAK , GILLESPIE TOM , GRETHE JEFFREY S. , MARTONE MARYANN E.
Published: June 2018

The NIDDK Information Network (dknet.org) is a portal for basic and clinical investigators that makes it easier to discover, obtain, and reuse scientific research resources. Here we demonstrate how dkNET can connect researchers to resources for obesity research. A search for “obesity” returns 264,498 results (Table 1), including physical resources (i.e., antibodies, cell lines, model organisms), digital resources, data, models, funding, and knowledge bases. dkNET facilitates discovery not only within well known databases like GEO, Mouse Phenome Database, or model organism databases such as MMRRC, but also many unique but less well known databases, such as Animal Quantitative Trait Loci or Aging Gene/Interventions databases. dkNET provides some basic analytic tools, e.g., word clouds, category graphs, to aid exploration. dkNET provides in depth information on how resources are used through Research Resource Identifier (RRID), a unique ID allowing dkNET to aggregate and provide information, e.g., about known problems with antibodies or cell lines. To assist researchers in complying with NIH guidelines on rigor and transparency, dkNET provides a tool to suggest authentication plans for key research resources. dkNET also provides reports to track resource utilization. These new services aim to not only enhance transparency of research but also ensure that resource creators are appropriately credited.

Disclosure

K. Lin: None. A. Bandrowski: None. J. Go: None. I. Ozyurt: None. T. Gillespie: None. J.S. Grethe: None. M.E. Martone: None.
Loss of Adipocyte MDM2 Causes Lipodystrophy by Inducing P53-Dependent Apoptosis and Senescence
Authors: LIU ZHUOHAO , JIN LEIGANG , WANG BAILE , CHENG KENNETH K.Y. , XU AIMIN
Published: June 2018

Adipose tissue is crucial for the maintenance of metabolic health. Activation of tumor suppressor p53 is known to induce adipose tissue dysfunction and its related metabolic diseases in obesity and aging. Here we show that murine double minute 2 (MDM2) acts as a gatekeeper of adipose health by restraining p53-mediated apoptosis and senescence. Adipocyte-specific deletion of MDM2 induces chronic and unrestrained activation of p53, which in turn triggers progressive loss of adipose tissues. Similar to other mouse models with lipodystrophy, mice lacking of adipocyte MDM2 develop hyperglycemia, hyperinsulinemia, hyperlipidemia and massive nonalcoholic fatty liver. Adiponectin-Cre-mediated deletion of MDM2 has no obvious effect on adipogenesis in cell-autonomous manner but induces apoptotic and senescent program in white and brown adipocytes. To ascertain whether the activation of p53 is responsible for the MDM2-null phenotypes, we generated an adipocyte specific MDM2-p53 double knockout mouse model. As expected, lipodystrophy and its associated metabolic disorders are not observed in adipocyte-MDM2-p53 double knockout mice. In addition, transplantation of subcutaneous white adipose tissue largely reverses diabetes, dyslipidemia and nonalcoholic fatty liver in adipocyte-specific MDM2 knockout mice. Together, our data suggest that the balance of MDM2-p53 signaling axis is crucial for proper functions and turnover of adipose tissues.

Disclosure

Z. Liu: None. L. Jin: None. B. Wang: None. K.K.Y. Cheng: None. A. Xu: None.
Stimulation of the ß3-Adrenergic Receptor via Mirabegron Induces Lipolysis and Thermogenesis in Human Adipocytes
Authors: CERO CHERYL , O'MARA ALANA , JOHNSON JAMES W. , BASKIN ALISON S. , LINDERMAN JOYCE D. , CYPESS AARON
Published: June 2018

In rodent models, the β3-adrenergic receptor (AR) is responsible for thermogenesis in brown adipose tissue (BAT) and lipolysis in white adipose tissue (WAT). In contrast, the contribution of β3-AR in human adipocytes is controversial due to the low expression of the β3-AR in WAT and access only to partial β3-AR agonists. Mirabegron, an FDA-approved drug for overreactive bladder, is a selective human β3-AR agonist. In a recent clinical trial, mirabegron activated human BAT thermogenesis and WAT lipolysis. Therefore, we investigated the distribution and relative contribution of β1/2/3-AR in (i) whole white (hWAT) and brown (hBAT) adipose tissue from human autopsies and (ii) immortalized human white (hWA) and brown (hBA) adipocytes. Among the three β-ARs, β1-AR and β2-AR are similarly expressed in brown and white adipose tissue, whereas β3-AR has the highest expression in hBAT. In immortalized differentiated cells, hBA have a significantly higher expression of β3-AR compared to hWA. To assess the functionally of these receptors in adipocytes, dose-response curves of agonist-stimulated lipolysis were investigated in differentiated human and mouse adipocytes. We observed that stimulation of any one of the three β-ARs in human adipocytes induces a significant increase in glycerol release, a lipolytic byproduct. However, the effective dose of mirabegron to activate β3-AR-mediated lipolysis in white and brown adipocytes via mirabegron was significantly lower (hWA: EC50 2.55E-09; hBA: EC50 6.31E-09) compared to specific activators of β1-AR or β2-AR.

In summary, we identify a major role played by the β3-AR in the regulation of human BAT thermogenesis and WAT lipolysis, both in vivo and in vitro. Due to the comparatively minimal effects of mirabegron treatment on the cardiovascular system, selective β3-AR agonists may be the optimal choice for targeted stimulation of human WAT and BAT.

Disclosure

C. Cero: None. A. O'Mara: None. J.W. Johnson: None. A.S. Baskin: None. J.D. Linderman: None. A. Cypess: None.
Significant Bone Loss in Obese Patients with Acanthosis Nigricans after LSG—One-Year Follow-Up Study
Authors: ZHANG YOUYANG , ZHANG ZHIYIN , ZHU CUILING , SUN SIQI , YIN YING , CUI RAN , SHENG HUI , QU SHEN
Published: June 2018

The aim of the study was to investigate the longitudinal bone mineral density(BMD) and bone metabolic related markers changes in obese patients with acanthosis nigricans (AN) and without AN(OB) after Laroscopic Sleeve Gastrectomy (LSG). 41 obese patients (AN group:n=29,OB group:n=12) were recruited in this study. Areal BMD (aBMD) and lumbar spine volumetric BMD (vBMD)were measured by dual-energy X-ray absorptiometry (DXA) and quantitative computed tomography (QCT). Insulin and markers of bone metabolism including 25-OHD, calcium, intact parathyroid hormone (iPTH), osteocalcin (OC), and type I collagen cross-linked C-terminal telopeptide (CTX) ] were assessed; Insulin area under the curve(AUCins) and HOMA-IR were computed. Results showed that the AN group had a higher fasting serum insulin (42.80±28.52 vs. 22.55±8.94mU/L,p=0.006), AUCins (522.42±280.32 vs. 263.87±195.75mU/L,p=0.008)and BMI(40.6±5.1 vs. 36.7±4.1kg/m2,p=0.024) compared to the OB group at baseline. The both groups did a obvious decrease in HOMA-IR after LSG; In AN group, there was a significant decrease in Lumbar vBMD(-4.4%,p=0.011), pelvic aBMD (-6.48%,p<0.001) and femoral neck aBMD (-6.7%,p=0.045) after LSG compared with baseline, whereas no detectable BMD changes in the OB group. CTX and OC increased in both AN (97.69%,79.65%,respectively)and OB(115.21%,62.28%,respectively) groups; No significant alteration of 25-OHD, serum calcium, or iPTH was observed.

In conclusion, Insulin resistance was improved, and bone turnover was activated one year after LSG in both groups, but the bone loss was more likely to occur in the obese patients with acanthosis nigricans.

Disclosure

Y. Zhang: None. Z. Zhang: None. C. Zhu: None. S. Sun: None. Y. Yin: None. R. Cui: None. H. Sheng: None. S. Qu: None.
Increased Bile Acids and FGF-19 after Sleeve Gastrectomy and Roux-en-Y Gastric Bypass Correlate with Improvement in Type 2 Diabetes in a Randomized Trial
Authors: MURPHY RINKI , NEMATI REZA , DOKPUANG DECH , LU JUN
Published: June 2018

Background: Sleeve gastrectomy (SG) and Roux-en-Y gastric bypass (RYGB), are both effective bariatric procedures to treat type 2 diabetes (T2DM) and obesity. The contribution of changes in bile acids (BAs) and fibroblast growth factor19 (FGF-19) to such metabolic improvements is unclear.

Methods: We examined associations between changes in BAs, FGF-19 (fasting and prandial), with changes in body weight, glycemia and other metabolic variables in 61 obese patients with T2DM before and one year after randomisation to SG or RYGB.

Results: Weight loss and diabetes remission (defined by HbA1c <39mmol/mol [<5.7%] in absence of glucose lowering therapy) after RYGB and SG was similar (mean weight loss -29kg vs. -31kg, p=0.50; diabetes remission proportion 37.5% vs. 34%, p=1.0). Greater increments in fasting and prandial levels of total, secondary and unconjugated BAs were seen after RYGB than SG. Fasting and prandial increases in total (r=-0.3, p=0.01; r=-0.2, p=0.04), secondary (r=-0.3, p=0.01; r=-0.4, p=0.01) and unconjugated BA (r=-0.3, p=0.01; r=0.4, p<0.01) correlated with decreases in HbA1c, but not weight. Changes in 12α-OH/non 12α-OH were positively associated with prandial glucose increments (r=0.2, p=0.03), HbA1c (r=0.3, p=0.01) and negatively associated with changes in insulinogenc index (r=-0.3, p=0.01). Only changes in prandial FGF-19 were negatively associated with HbA1c (r=-0.4, p<0.01) and visceral fat (r=-0.3, p=0.04).

Conclusions/Interpretation: The modest association between increases in secondary, unconjugated BAs and improvements in HBA1c, (but not weight) achieved after both RYGB and SG suggest augmentation of BA signalling as one potential strategy for controlling T2DM through weight independent means.

Disclosure

R. Murphy: None. R. Nemati: None. D. Dokpuang: None. J. Lu: None.
Lactational Programming of Offspring Glucose Homeostasis and Body Composition by Early Postnatal Metformin Exposure
Authors: GREGG BRIGID
Published: June 2018

Background: The early postnatal period is a critical window for programming of long-term metabolic health. Our previous studies have shown that gestational metformin exposure increases pancreatic beta-cell fraction at birth and improves glucose homeostasis in adulthood.

Hypothesis: We hypothesized that metformin administration to dams during the critical window of lactation would alter neonatal nutrient exposure and the acquisition of the gut microbiome from the mother leading to a permanent change in offspring metabolic tissues.

Methods: We used C57BL/6J mice for the developmental programming studies in this experiment. Metformin was delivered in drinking water to dams from postnatal day 1 (P1) and continued through the lactation period to P21 (Met PN group). Offspring were examined during lactation and as adults. Dams were examined during lactation and upon weaning. Gut microbe composition was determined by 16s sequencing in dams and offspring.

Results: Dams on metformin showed improved glucose tolerance at weaning. Met PN pups had lower body weights that began during the first 3 weeks of life and persisted to 6 months. On intraperitoneal glucose tolerance testing male but not female offspring had improved glucose responses at 2 months and increased glucose stimulated insulin secretion. Met PN offspring had a lower body fat percentage at necropsy. Stool microbiome studies showed that Met PN pups had an altered intestinal colonization that persisted into adulthood with an increase in the bacteroidetes:firmicutes ratio at the time the lower weight trajectory was established. A lower bacteroidetes:firmicutes ratio has been associated with obesity.

Conclusions: These findings suggest that limited early postnatal exposure to a dam on metformin results in long-term programming of offspring weight, insulin secretion and intestinal microbiome.

Disclosure

B. Gregg: None.
Caveolin-1 Deficiency Inhibits Palmitate-Induced Intracellular Lipid Accumulation and Enhances Autophagy in Pancreatic ß Cells via AMPK/mTOR Pathway
Authors: ZENG WEN , LIU KUNYING , TANG JIANSONG , PENG HANGYA , LIN CHUWEN , LIN SHUO , LIN KEYI , JIANG YAN , ZENG LONGYI
Published: June 2018

Lipotoxicity induced intracellular lipid accumulation in pancreatic β cells, one of the strongest predictors for T2DM. The objective of this study is to explore the role of Cav-1 in intracellular lipid accumulation of β cells under lipotoxicity condition. Our data showed that Cav-1 silencing significantly reduced PA-induced intracellular triglyceride (TG) accumulation, enhanced autophagy and insulin secretion in NIT-1 cells and murine pancreatic islets. Further investigation found that Cav-1 depletion facilitated AMPK phosphorylation, decreased the expression of downstream lipogenic makers (SREBP-1c, FAS and ACC) and increased the expression of fatty acid oxidation maker (CPT-1), leading to the ultimate enhancement of lipid metabolism. Meanwhile, Cav-1 depletion also suppressed mTOR phosphorylation, decreased the expression of p62 protein and increased the expression of LC3-II proteins, resulting in the ultimate increase of autophagy. Subsequent inhibition of AMPK and mTOR pathways abolished Cav-1 depletion mediated autophagy enhancement and TG content reduction, leading to the reduction of insulin secretion. Our findings suggest the potential application of the Cav-1 molecule as a target for effective T2DM treatment through preservation of lipotoxicity-induced β-cell intracellular lipid accumulation and dysfunction.

Disclosure

W. Zeng: None. K. Liu: None. J. Tang: None. H. Peng: None. C. Lin: None. S. Lin: None. K. Lin: None. Y. Jiang: None. L. Zeng: None.
Liraglutide Inhibits Endoplasmic Reticulum Stress in Pancreatic Beta Cells via Regulation of the Homeodomain Transcription Factor Nkx6.1
Authors: LI YUKUN , DONG YANAN , SHILUN LI , XUE PENG
Published: June 2018

The GLP-1 mitigates the endoplasmic reticulum (ER) stress in β cells. Nkx6.1 plays an important role in the development and survival of β cells. This study aims to investigate the relation of Nkx6.1 and liraglutide in the protection effect of endoplasmic reticulum stress in INS-1-3 cells. INS-1-3 cells were divided into different groups for treatment: control group, thapsigargin (TG)-treated group, TG and GLP-1 co-treated group. Knockdown of Nkx6.1 was established by lentivirus infection. RT-PCR was used to verify the expression changes of target genes. MTT and flow cytometry analysis were used to detect cell viability and apoptosis rates. Glucose stimulates insulin secretion (GSIS) was used to measure β cell function. In TG-treated cells, liraglutide significantly increased cell viability and GSIS by 1.53 and 1.89 folds. These were associated with the suppression of the PERK, IRE1 and ATF-6 pathways. Knock down of Nkx6.1 partially diminished protective effect of liraglutide. The cell viability and GSIS were decreased by 24.7% and 54.0%. And both of the early and late apoptosis were increased by 1.55, 1.10 folds. Liraglutide protected INS-1-3 cells from TG-induced ER stress by suppressing the PERK, IRE1 and ATF-6 pathways. And its protective effects on ER stress was partially via transcription factor Nkx6.1.

Disclosure

Y. Li: None. Y. Dong: None. L. Shilun: None. P. Xue: None.
Effects of Extra Virgin Olive Oil Polyphenols on Pancreatic Beta-Cell Function and Survival
Authors: NATALICCHIO ANNALISA , SPAGNUOLO ROSARIA , MARRANO NICOLA , BIONDI GIUSEPPINA , DIPAOLA LUCIA , CIGNARELLI ANGELO , PERRINI SEBASTIO , LAVIOLA LUIGI , GIORGINO FRANCESCO
Published: June 2018

Extra virgin olive oil (EVOO) is one of the major components of the Mediterranean diet and is appreciated worldwide because of its nutritional benefits in metabolic diseases, including type 2 diabetes. In addition to high levels of fatty acids, EVOO contains significant amounts of micronutrients such as polyphenolic compounds that may positively influence the metabolic status. In this study, we have evaluated the effects of such EVOO polyphenolic compounds on beta-cell function and survival. INS-1E cells were exposed to different doses (10-50-100 microM) of the main polyphenols of EVOO for 24 h. Under these conditions, glucose-stimulated insulin secretion (GSIS), insulin content, proinsulin mRNA expression and cellular apoptosis were evaluated. At the concentration of 10 microM, which is closest to that in EVOO, hydroxytyrosol, tyrosol and apigenin augmented proinsulin mRNA levels and insulin content; moreover, apigenin and luteolin enhanced GSIS. On the other hand, vanillic acid and vanillin were pro-apoptotic for beta-cells, even if they increased GSIS. Finally, ferulic and sinapic acids significantly worsened GSIS. Furthermore, although most of the polyphenol compounds at the concentration of 50 microM did not induce apoptosis, some of them (e.g., caffeic, vanillic and ferulic acids) caused a marked reduction in proinsulin gene expression. At the concentration of 100 microM, most polyphenolic compounds caused a reduction in proinsulin mRNA levels and enhanced apoptosis.

In conclusion, this study, comparing for the first time the effects of the main polyphenols contained in EVOO, shows that, at low concentrations, hydroxytyrosol, tyrosol, luteolin and apigenin exert positive effects on both the function and survival of beta-cells, suggesting that EVOO enriched with these compounds may improve insulin secretion and promote glycemic control in type 2 diabetic patients.

Disclosure

A. Natalicchio: None. R. Spagnuolo: None. N. Marrano: None. G. Biondi: None. L. Dipaola: None. A. Cignarelli: Advisory Panel; Self; Aegerion Pharmaceuticals. Consultant; Self; Roche Diagnostics Corporation, Eli Lilly and Company. S. Perrini: None. L. Laviola: Advisory Panel; Self; AstraZeneca, Animas Corporation. Speaker's Bureau; Self; A. Menarini Diagnostics. Advisory Panel; Self; Boehringer Ingelheim GmbH, Eli Lilly and Company. Speaker's Bureau; Self; Medtronic, Merck Sharp & Dohme Corp.. Advisory Panel; Self; Novo Nordisk Inc., Roche Diabetes Care Health and Digital Solutions, Sanofi-Aventis, Takeda Development Centre Europe Ltd. F. Giorgino: Consultant; Self; Abbott, AstraZeneca, Boehringer Ingelheim GmbH. Research Support; Self; Eli Lilly and Company, Johnson & Johnson Services, Inc.. Consultant; Self; MedImmune, Merck Sharp & Dohme Corp., Roche Diabetes Care Health and Digital Solutions, Sanofi. Research Support; Self; Takeda Development Centre Europe Ltd..
Discovery and Replication of HDL-Associated Loci in the Korean Population Using 35,000 Individuals
Authors: KIM BONG-JO , KIM YOUNG JIN , HWANG MI YEONG , MOON SANGHOON
Published: June 2018

Low levels of HDL are known to be associated with increased risk of type 2 diabetes. It has been suggested as a new therapeutic approach that increase HDL levels in plasma. Previously, to identify lipids traits associated loci, we performed large-scale genome-wide meta-analyses comprising 25,923 East Asian individuals from 11 studies from Korea, Japan, Philippines, China, Singapore, and Taiwan in the discovery stage. With subsequent replication study, we have revealed seven novel loci associated with HDL including loci at CD163-APOBEC1, NCOA2, and NID2-PTGDR. However, previous study was limited in sample size in the discovery stage and low association mapping resolution due to HapMap based imputation analysis. In this study, we performed genome-wide association analyses (GWAS) on HDL using about 35,000 Korean samples and imputed based on 1,000 Genomes project phase 3 and Korean Reference Genome. We focused on imputed (imputation quality score >0.4) and genotyped common variants with minor allele frequency >= 1%. In this discovery study, 17 known loci were replicated at the genome-wide significance level (P<5x10-8). However, no novel association meet the genome-wide significance. We further examined associated loci at suggestive statistical significance (P<5x10-6). As a result, 11 known loci were additionally replicated and 10 possible novel candidate loci were identified including a variant near GATA4. It is noteworthy that the variant near GATA4 was previously reported to be associated with triglyceride level.

In summary, we performed a GWAS on HDL using about 35,000 Korean samples. The GWAS confirmed 28 known loci and discovered 10 possible novel candidate loci responsible for variation of HDL level. However, a replication study in an independent cohort is warranted for validating the results. Taken together, the possible novel candidates discovered from this study may provide potential novel therapeutic targets for diseases associated with HDL.

Disclosure

B. Kim: None. Y. Kim: None. M. Hwang: None. S. Moon: None.
Exploring the Role of Calcium-Activated Potassium Channels in Alpha-Cell Function
Authors: DICKERSON MATTHEW , ALTMAN MOLLY K. , DADI PRASANNA , VIERRA NICHOLAS C. , JACOBSON DAVID
Published: June 2018

Calcium influx into pancreatic α-cells through voltage-dependent calcium channels (VDCCs) is required for glucagon (GCG) secretion and the mechanisms that mediate this process become defective during the pathogenesis of diabetes. Potassium channels are key regulators of membrane potential (Vm), and thus, modulate VDCC activity. However, the role of calcium-activated potassium (KCa) channels in α-cell calcium handling and GCG secretion have not been determined.

The aim of this study was to investigate the importance of KCa channels to α-cell electrical excitability, calcium handling, and GCG secretion. α-cells display a KCa current, which is partially inhibited by blocking small conductance KCa (SK) or big conductance KCa (BK) channels. Inhibition of P/Q-type VDCCs, sarco/endoplasmic reticulum (ER) calcium-ATPases (SERCAs), and KATP channels also partially inhibit this current. It is likely that calcium influx through VDCCs triggers calcium-induced calcium release (CICR) from ER calcium stores activating α-cell KCa channels. The inhibition of SK channels transiently increases calcium influx into α-cells at 1 mM glucose; however, over time intracellular calcium decreases. This may be due to voltage-dependent inactivation of α-cell VDCCs. Interestingly, SK channel inhibition reduces GCG secretion at 1 mM glucose while SST secretion is unaffected. Thus, it is likely that this is an intrinsic α-cell effect. These findings demonstrate that α-cells possess a KCa current and that its activation is important for α-cell electrical activity, Ca2+ handling, and GCG secretion.

Disclosure

M. Dickerson: None. M.K. Altman: None. P. Dadi: None. N.C. Vierra: None. D. Jacobson: None.