bluuebunny/crossref_metadata_2025_split huggingface dataset:
Hyperglycemia Promotes Muscle Atrophy through the WWP1/KLF15 Pathway
Authors: HIRATA YU , NOMURA KAZUHIRO , SENGA YOKO , IMAMURA MICHIHIRO , TAKEDA SHIN’ICHI , OKADA YUKO , BURDEN STEVEN J. , HOSOOKA TETSUYA , OGAWA WATARU 
Published: June 2018

Background: Evidence suggests that diabetes is a promoting factor of sarcopenia. Mechanism how the condition accelerates the development of sarcopenia remains ambiguous.
Results: In streptozotocin (STZ)-induced diabetic mice, skeletal muscle mass was decreased by ∼15 % within 21 days after the STZ treatment. The protein abundance of transcription factor KLF15 as well as the mRNA abundance of proteins related to muscle atrophy (Foxo3a, Atrogin1 and Murf1) were elevated whereas the mRNA of KLF15 was unaltered in skeletal muscle of STZ-diabetic mice. Decrease in skeletal muscle mass and increase in the mRNA abundance of muscle atrophy-related proteins triggered by STZ-induced diabetes were prevented in muscle-specific KLF15 deficient mice suggesting that KLF15 plays a key role in diabetes-induced muscle atrophy. Treatment of C2C12 cells with high concentration of glucose (25 mmol/l) decreased the ubiquitination of and increased the protein abundance of KLF15. The E3 ubiquitin ligase WWP1 was found to be downregulated in skeletal muscle of STZ- diabetic mice and in C2C12 cells treated with glucose. Overexpression and knockdown of WWP1 in C2C12 cells resulted in the decrease and the increase, respectively, of KLF15 protein without affecting its mRNA expression. The mRNA abundance of WWP1 in skeletal muscle was downregulated and the mass of skeletal muscle was reduced in Akita mice, which develop diabetes due to beta-cell dysfunction. Administration of the SGLT2 inhibitor empagliflozin, which lowers glycemia without affecting insulin levels, to Akita mice upregulated the expression of WWP1 in skeletal muscle and increased the skeletal muscle mass of these mice.
Conclusion: Our results suggest that hyperglycemia upregulates the protein abundance of KLF15 via the downregulation of WWP1, which catalyzes the ubiquitination of KLF15. Hyperglycemia-induced upregulation of KLF15 leads to the induction of genes for muscle atrophy-related proteins, which in turn promotes the atrophy of skeletal muscle.

Disclosure
Y. Hirata: Research Support; Self; Boehringer Ingelheim Pharmaceuticals, Inc. K. Nomura: Research Support; Self; Boehringer Ingelheim Pharmaceuticals, Inc. Y. Senga: Research Support; Self; Boehringer Ingelheim Pharmaceuticals, Inc.. M. Imamura: None. S. Takeda: None. Y. Okada: Research Support; Self; Boehringer Ingelheim Pharmaceuticals, Inc.. S.J. Burden: None. T. Hosooka: Research Support; Self; Boehringer Ingelheim Pharmaceuticals, Inc. W. Ogawa: Research Support; Self; Boehringer Ingelheim Pharmaceuticals, Inc., Abbott.
Mitochondrial Adaptation in Insulin Resistant Human Skeletal Muscle
Authors: AXELROD CHRISTOPHER L. , FEALY CIARAN E. , MULYA ANNY , HUANG EMILY , FUJIOKA HISASHI , BURGUERA BARTOLOME , HOPPEL CHARLES L. , KIRWAN JOHN P. 
Published: June 2018

Introduction: The integrity, morphology, structure and functionality of skeletal muscle mitochondria in patients with type 2 diabetes (T2D) is heavily disputed. Thus, the purpose of this investigation was to characterize mitochondrial phenotypes across the insulin resistance spectrum.
Methods: 30 sedentary adults aged 18-55 were grouped as lean (BMI 21±0.6, N=13), obese (BMI 32±0.9, N=12), or T2D (BMI 33±2.5, N=5) based on oral glucose tolerance tests and body mass index (BMI). All subjects completed a 3-day, inpatient stay consisting of cardio-metabolic testing, body composition analysis and a hyperinsulinemic-euglycemic clamp study. On the day of the clamp, muscle specimens were obtained basally and under insulin-stimulated conditions. Mitochondrial membrane potential (δψm) was measured by confocal microscopy using the cationic fluorophore TMRM. Oxidative phosphorylation (OXPHOS) was assessed in permeabilized fibers via high resolution respirometry (Oroboros Oxygraph-2k). Muscle mitochondrial ultrastructure and content were determined by transmission electron microscopy (TEM) of fixed muscle sections.
Results: There was a significant, step-wise decrease in insulin-stimulated glucose uptake across the metabolic spectrum (P&lt;0.001). No differences in resting δψm were observed, however, insulin stimulation depolarized δψm in all groups (P&lt;0.05). Those with T2D exhibited increased basal complex III (P&lt;0.05) and IV (P&lt;0.05) activity vs. lean and obese controls. Furthermore, obese controls and T2D displayed augmented complex IV responsiveness to insulin stimulation (P&lt;0.01). Threshold analysis of muscle sections revealed a progressive loss of mitochondrial content, as well as accumulation of lipid droplets across the metabolic spectrum (P&lt;0.05).
Conclusion: Collectively, these findings provide direct evidence of mitochondrial adaptation in insulin resistant and diabetic skeletal muscle.

Disclosure
C.L. Axelrod: None. C.E. Fealy: None. A. Mulya: None. E. Huang: None. H. Fujioka: None. B. Burguera: None. C.L. Hoppel: None. J.P. Kirwan: None.
Age-Related Attenuation of Aerobic Exercise Training Adaptation in 24-Week Old Rats
Authors: SCALZO REBECCA L. , EVANS GRAHAME F. , HULL SARA E. , KNAUB LESLIE , WALKER LORI A. , REUSCH JANE E. 
Published: June 2018

Studies of age related declines in health and function often focus on the end of the lifespan. However, chronic diseases such as type 2 diabetes (T2D) develop in middle age. The purpose of this study was to determine the effect of aerobic exercise training on vascular and skeletal muscle responses in mature rats. We hypothesized that mature rats would have attenuated adaptations to exercise training. Young (Y; 12-week old; n = 8) and mature (M; 24 week-old; n = 8) male Wistar rats performed 3-weeks of treadmill running (Ex) or remained sedentary (S). After this time period, insulin and glucose were greater in mature compared with young rats (P &lt; 0.03) and were not different with Ex. Mature rats had lower exercise capacity measured by run to fatigue distance (Y-S: 675 ± 172 vs. M-S: 585 ± 22 m; P &lt; 0.001) and a significantly reduced change in exercise capacity in response to exercise training (Y-Ex: 2387 ± 177 vs. M-Ex: 1341 ± 161 m; P &lt; 0.01). Ex vivo aortic function in response to phenylephrine was impaired and aortic mitochondrial respiration was elevated in mature animals (P &lt; 0.01) and neither endpoint responded to exercise training in the mature rats. Skeletal muscle AMPK activation was 81% greater in the Y-Ex compared with Y-S and this response was attenuated (8% greater) in the M-Ex compared with M-S (P = 0.05). Similarly, muscle PGC1α was greater with exercise training in the young rats and this response was abrogated in the mature rats (P = 0.05).
In summary, mature rats develop insulin resistance and have lower exercise capacity and training adaptation. Vasomotion is impaired and skeletal muscle bioenergetic adaptation to Ex is blunted. As exercise is a cornerstone of therapy for T2D, it is crucial to define the interaction between age and exercise adaptation, and to determine whether T2D modulates or accelerates the impact of age. Future studies will focus on understanding the mechanisms of this age related impairment of exercise adaptation for identification of optimal exercise training and/or pharmacological interventions.

Disclosure
R.L. Scalzo: None. G.F. Evans: None. S.E. Hull: None. L. Knaub: None. L.A. Walker: None. J.E. Reusch: Research Support; Self; Merck & Co., Inc.. Board Member; Self; American Diabetes Association. Research Support; Self; AstraZeneca. Other Relationship; Self; Sanofi-Aventis.
Natriuretic Peptide Deficiency Causes Skeletal Muscle Insulin Resistance in Mice
Authors: MORO CEDRIC 
Published: June 2018

Cardiac natriuretic peptides (NP) have been shown to control energy homeostasis. Epidemiological studies have shown that low level of plasma NP predict future development of type 2 diabetes (T2D). We have also observed a reduced expression of the biologically active NP receptor GCA of about 50% in metabolic tissues of obese humans and mice. The purpose of this study was to demonstrate that NP deficiency causes T2D in mice. GCA+/- and atrial NP-/- (ANP) mice and their wild type (WT) littermates were studied under normal chow and high fat diet for 12 weeks. GCA+/- and ANP-/- mice exhibit signs of systemic insulin resistance and glucose intolerance when compared to their WT littermates. This metabolic phenotype is accompanied by skeletal muscle insulin resistance and reduced lipid oxidative capacity, without noticeable changes in inflammatory profile of liver and adipose tissues. Interestingly, we observed elevated levels of lipotoxic lipids in skeletal muscle along with reduced mitochondrial mass and respiratory chain complexes. Collectively, these data indicate that ANP/GCA deficiency causes T2D and that ANP contributes to long-term maintenance of insulin sensitivity.

Disclosure
C. Moro: None.
Multiyear Reproducibility of Clamp-Derived Insulin Sensitivity in Free-Living Humans—Association with Incident Prediabetes in the POP-ABC Study
Authors: UMEKWE NKIRU A. , JAMES DEIRDRE J. , DAGOGO-JACK SAMUEL 
Published: June 2018

Background: The hyperinsulinemic euglycemic clamp (HEC) is the gold standard measure for insulin sensitivity (Si-clamp). Here, we determined its reproducibility and metabolic implications.
Methods: POP-ABC is a follow-up study of healthy black and white offspring of parents with T2DM for the primary outcome of prediabetes. Assessments included clinical exam, OGTT, anthropometry, and HEC.
Results: 90 adults (44 AA, 46 EA; 62 women, 28 men) who underwent HEC-1 at baseline consented to HEC-2 after 2.3y (range 2-3.5 y) (Table 1). The mean (SD) baseline age was 47.5 ± 8.13y, BMI was 30.4 ± 9.16 kg/m2, FPG was 94.8 ± 7.92 mg/dl and 2-hrPG was 127.4 ± 26.8. HEC-1 and HEC-2 metrics did not differ significantly (Table 1). Si-clamp values from HEC-1 and HEC-2 were strongly correlated (r=0.81, P&lt;0.0001); the change in Si-clamp correlated with change in weight (r= 0.35, P=0.0009), but not age, gender, race, or FPG. After ∼5 y follow-up, 40 subjects progressed (P) to prediabetes and 50 were Nonprogressors (NP). Si-clamp was lower at baseline and 2.3 y later in P vs. NP (P=0.02). The mean change in Si-clamp (-2.5% in NP and -9.5% in P) predicted prediabetes risk (P=0.02).
Conclusion: Insulin sensitivity by HEC is reproducible over multiyear intervals in nondiabetic free-living subjects. Progressors to prediabetes showed ∼4% /y decline in Si-clamp vs. 1%/y in nonprogressors.

Disclosure
N.A. Umekwe: None. D.J. James: None. S. Dagogo-Jack: None.
Febuxostat Improves Insulin Resistance in the Skeletal Muscle In Vitro and In Vivo
Authors: MORIYA CHIHIRO T. , SATOH HIROAKI , WATADA HIROTAKA 
Published: June 2018

Hyperuricemia is closely associated with various metabolic disorders such as diabetes, hypertension, dyslipidemia, and cardiovascular diseases. Xanthine oxidoreductase (XOR) is a key enzyme known to catalyze purines to uric acid. Febuxostat is an orally-active, potent, non-purine, selective XOR inhibitor. However, the effect of febuxostat on glucose and insulin metabolism has not been fully elucidated. Therefore, we investigated the effect of febuxostat on insulin sensitivity in male Wistar rats. Insulin sensitivity was evaluated by the hyperinsulinemic-euglycemic glucose clamp studies (at 25 mU/kg/min insulin infusion rate) after an 8-hour fast. Male Wistar rats were 60% high fat diet containing with either febuxostat (∼4 mg/kg/day) or not, for 4 weeks. The glucose infusion rate and insulin-stimulated glucose disposal rate were significantly increased by 12% and 17%, respectively. But hepatic glucose output was no significant change between two groups. Consistent with the clamp data, the insulin-stimulated phosphorylation of Akt and AMPK were significantly increased by 90% and 53%, respectively, only in skeletal muscle of febuxostat treated rats. Next, to investigate whether this effect is direct or indirect, we examined the effect of febuxostat in the differentiated C2C12 cells. The treatment of 10 μM febuxostat for 48 hours significantly increased the phosphorylation of Akt and AMPK by 65% (P=0.017) and 43% (P=0.028) in the differentiated C2C12 cells, respectively. These results suggest that this effect of febuxostat is direct.
In conclusion, these findings indicate the possibility that febuxostat acts directly on the skeletal muscle and improves insulin resistance.

Disclosure
C.T. Moriya: None. H. Satoh: None. H. Watada: Advisory Panel; Self; AstraZeneca. Consultant; Self; Astellas Pharma US, Inc., AstraZeneca, Boehringer Ingelheim GmbH, Daiichi Sankyo Company, Limited, Sumitomo Dainippon Pharma Co., Ltd., Eli Lilly and Company, Kissei Pharmaceutical Co., Ltd., Kowa Pharmaceuticals America, Inc., Kyowa Hakko Kirin Co., Ltd., Merck Sharp & Dohme Corp., Mitsubishi Tanabe Pharma Corporation, Novo Nordisk A/S, Novartis AG, Ono Pharmaceutical Co., Ltd., Sanofi, Sanwa Kagaku Kenkyusho Co., Ltd., Takeda Development Center Asia, Pte. Ltd.. Research Support; Self; Abbott, Astellas Pharma US, Inc., AstraZeneca, Bayer AG, Benefit One Health Care Co., Ltd., Boehringer Ingelheim GmbH, Bristol-Myers Squibb Company, Daiichi Sankyo Company, Limited, Sumitomo Dainippon Pharma Co., Ltd., Eli Lilly and Company, Kissei Pharmaceutical Co., Ltd., Kowa Pharmaceuticals America, Inc., Kyowa Hakko Kirin Co., Ltd., Johnson & Johnson Diabetes Institute, LLC., Merck Sharp & Dohme Corp., Mitsubishi Tanabe Pharma Corporation, Mochida Pharmaceutical Co., Ltd., Nitto Boseki Co., Ltd., Novartis AG, Novo Nordisk A/S, Ono Pharmaceutical Co., Ltd., Pfizer Inc., Sanofi, Sanwa Kagaku Kenkyusho Co., Ltd., Taisho Pharmaceutical Co., Ltd., Takeda Development Center Asia, Pte. Ltd., Terumo Medical Corporation.
Deoxysphingolipids—Novel Skeletal Muscle Lipids Related to Insulin Resistance in Humans That Decrease Insulin Sensitivity In Vitro
Authors: ZARINI SIMONA , PERREAULT LEIGH , NEWSOM SEAN A. , KAHN DARCY E. , KEREGE ANNA , HARRISON KATHLEEN A. , BERGMAN BRYAN 
Published: June 2018

Accumulation of sphingolipids are thought to promote skeletal muscle insulin resistance. Deoxysphingolipids (dSL) are a novel type of sphingolipid made by condensing palmitate with alanine (deoxydihydroceramide - dDHCer) or glycine (deoxymethylceramide - dMeCer) instead of serine. In plasma, dSL are increased in individuals with type 2 diabetes and cause beta cell dysfunction in vitro. However, their role in skeletal muscle is unknown. We evaluated skeletal muscle dSL content in endurance trained athletes (n=13), lean (n=14), obese (n=12), and type 2 diabetic (n=10) men and women. Muscle dSL content was measured from biopsies using LC/MS/MS, and insulin sensitivity using a hyperinsulinemic-euglycemic clamp. After adjusting for repeated measures, total and C18:0 muscle dDHCer were inversely related to insulin sensitivity (p=0.0008, and p=0.0003, respectively), while dMeCer were below the limit of detection. Total and C18:0 dDHCer were significantly greater in obese and T2D compared to athletes and lean (p&lt;0.004). In primary myotubes, dSL content was increased to determine effects on insulin sensitivity by altering media amino acid content with 5x alanine/glycine (no serine) or 1x alanine/glycine/serine as a control, and replaced every 24 hours for 2 days. Alanine and glycine supplementation increased myotube dDHCer content by 3.6 fold, dMeCer content by 21 fold, and decreased ceramide content by 30% relative to control. Fluorescence lifetime imaging revealed decreased oxidative flux in enhanced dSL conditions. Insulin sensitivity, measured using the percent increase in insulin stimulated glycogen synthesis, decreased from 55±9.1% in control to 4±9% in enhanced dSL conditions. Combined, these data reveal that dSL accumulate in insulin resistant human muscle, and appear to cause insulin resistance in vitro. These data suggest decreasing skeletal muscle deoxysphingolipid content may prevent or treat skeletal muscle insulin resistance.

Disclosure
S. Zarini: None. L. Perreault: Advisory Panel; Self; Novo Nordisk A/S. Speaker's Bureau; Self; Novo Nordisk A/S. Advisory Panel; Self; Merck & Co., Inc.. Speaker's Bureau; Self; Merck & Co., Inc., AstraZeneca, Janssen Pharmaceuticals, Inc., Boehringer Ingelheim Pharmaceuticals, Inc.. Consultant; Self; Boehringer Ingelheim Pharmaceuticals, Inc.. Advisory Panel; Self; Sanofi. Speaker's Bureau; Self; Sanofi. S.A. Newsom: None. D.E. Kahn: None. A. Kerege: None. K.A. Harrison: 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.
Weight Loss and Exercise Decrease Saturation of Intramyocellular Lipid Species in Association with Improvements in Insulin Sensitivity
Authors: STANDLEY ROBERT , COEN PAUL M. , GOODPASTER BRET H. 
Published: June 2018

Observational cross-sectional studies have described associations between the saturation status of both phospholipids and diacylglycerol (DAG) with insulin sensitivity (IS) of skeletal muscle. The purpose of this study was to test the hypothesis that diet-induced weight loss and exercise reduce intramyocellular lipid saturation and that this is associated with improved IS. We studied forty subjects who competed a randomized controlled trial (RCT) consisting of 6 months of either Health Education Control (CON: n=13 5M/8F), Diet-induced weight-loss only (DIWL: n=13 5M/8F), or Weight-loss and Exercise (WLEX: n=14 6M/9F). DIWL and WLEX subjects had a goal of 10% weight-loss through calorie restriction. Hyperinsulinemic euglycemic clamps were employed to measure IS, and muscle biopsies were obtained to quantify intramyocellular lipids by mass spectrometry. The DIWL and WLEX groups both lost a significant amount of weight compared to CON (DIWL: -6.4%, WLEX: -11.3%, CON: -2.5%, P&lt;0.05). IS measured as the glucose infusion rate required to maintain euglycemia during the clamp increased in the DIWL and WLEX groups compared to the control group (DIWL: 1.0, WLEX: 2.7, CON: 0.6 mg/FFMkg/min, P&lt;0.05). Total phosphatidylethanolamine (PE), phosphatidylcholine (PC), diacylglycerols (DAG) did not significantly change following intervention (P&gt;0.05). However, there were trends for unsaturated PE and PC species to increase in the WLEX only and saturated DAG and ceramide species to be reduced in both the DIWL and WLEX group. The increase in unsaturation of PE and PC were associated with improvements in IS (PE: P=0.047, r=0.35; PC: P=0.072, r=0.32) and the decrease in saturation of DAG was associated with improvements in IS (P=0.044, r=-0.36).
In conclusion, weight-loss and exercise increase unsaturated PE and PC species, and reduce saturated DAG species, which are related to improved IS within skeletal muscle.

Disclosure
R. Standley: None. P.M. Coen: None. B.H. Goodpaster: None.
Impact of Longitudinal Changes in Metabolic Syndrome Status Over Two Years on 10-Year Incident Type 2 Diabetes Mellitus
Authors: HUH JI HYE , LEE SUJIN 
Published: June 2018

Aim: Metabolic syndrome (MetS) is a known predictor of diabetes mellitus (DM), but whether longitudinal changes in MetS status modify the risk for DM remains unclear. We investigated whether temporal changes in MetS status over two years modify the 10-year risk of incident DM.
Methods: A prospective cohort study was conducted in 7,317 adults aged 40-70 years without DM at baseline. Subjects were categorized into four groups based on repeated longitudinal assessment of MetS status over two years: non-MetS, resolved MetS, incident MetS, and persistent MetS. The hazard ratio (HR) of new-onset DM during 10 years was calculated in each group using Cox models.
Results: During the 10-year follow-up, 1,099 (15.0%) developed DM. Compared to the non-MetS group, the fully adjusted hazard ratios for new-onset DM were 1.27 (1.01-1.61) in the resolved MetS group, 1.78 (1.43-2.22) in the incident MetS group, and 1.85 (1.52-2.26) in the persistent MetS group (P for trend &lt;0.001). The risk of DM in subjects with resolved MetS was attenuated compared to those with persistent MetS over two years (P&lt;0.001). The adjusted hazard ratio for 10-year developing DM gradually increased as the number of MetS components increased two years later (Figure 1).
Conclusion: We found that discrete longitudinal changes pattern in MetS status over two years associated with 10-year risk of DM. These findings suggest that monitoring change of MetS status and controlling it may be important for risk prediction of DM.

Disclosure
J. Huh: None. S. Lee: None.
Contribution of Pancreatic Alpha-Cell Function to Insulin Sensitivity and Glucose Variability in Type 1 Diabetes Patients
Authors: TAKAHASHI NOBUYUKI , CHUJO DAISUKE , KAJIO HIROSHI , UEKI KOHJIRO 
Published: June 2018

In type 1 diabetes (T1D) patients, relationships between pancreatic alpha cell function and glucose metabolism remain elusive. Therefore, we aimed to reveal the contribution of alpha cell function to insulin sensitivity, hepatic glucose uptake (HGU), and glucose variability, including the dawn phenomenon, in T1D patients. We recruited forty Japanese T1D patients with a median (interquartile range) BMI of 21.0 (19.3-22.7) kg/m2, diabetes duration of 2.6 (0.1-10.3) years, and HbA1c level of 8.2 (7.4-10.3) %. We measured the arginine-stimulated glucagon secretion using RIA and double-sandwich ELISA and subsequently assessed the dawn phenomenon using an artificial pancreas (STG-55®, Nikkiso, Japan) and performed a hyperinsulinemic-euglycemic clamp followed by oral glucose loading to evaluate insulin sensitivity and HGU. Glycemic variability was analyzed with continuous glucose monitoring (CGM). The median areas under the curve of glucagon measured by RIA (AUCglcRIA) and ELISA (AUCglcELISA) were 3.7 (2.6-4.6) × 104 and 1.9 (0.8-4.3) × 103 pg/mL × min, respectively. The glucose infusion rate (GIR) during the euglycemic clamp was inversely correlated with AUCglcRIA and AUCglcELISA (R2 = 0.21 and 0.44, P = 0.033 and 0.038, respectively, adjusted for age, sex, and BMI). In addition, the median GIR was significantly lower in the high glucagon response group than in the low glucagon response group [7.3 (5.1-8.4) vs. 9.2 (7.0-11.7), P = 0.049]. The dawn index (ratio of insulin requirements between 4:00-8:00 and 0:00-04:00) and HGU did not correlate AUCglcRIA and AUCglcELISA. The standard deviation of glucose levels determined by CGM significantly correlated with AUCglcRIA (R2 = 0.28, P = 0.015) but not with AUCglcELISA (R2 = 0.01, P = 0.62). In conslusion, alpha cell function may contribute to insulin sensitivity in T1D, and its relationship with glycemic variability may be affected by the procedure of the glucagon assay used.

Disclosure
N. Takahashi: None. D. Chujo: Research Support; Self; Mitsubishi Tanabe Pharma Corporation, Sanofi K.K., Kyowa Hakko Kirin Co., Ltd.. H. Kajio: None. K. Ueki: Speaker's Bureau; Self; Daiichi Sankyo Company, Limited, Eli Lilly and Company, Boehringer Ingelheim Pharmaceuticals, Inc., MSD K.K., Novo Nordisk Inc., Mitsubishi Tanabe Pharma Corporation, Kyowa Hakko Kirin Co., Ltd., Takeda. Research Support; Self; Takeda, Astellas, Novo Nordisk Inc..