INTEGRATED PHYSIOLOGY—INSULINCATEGORY SECRETION IN VIVO 1719-P INTEGRATED PHYSIOLOGY—INSULIN SECRETION Glucose-Induced Extracellular Matrix Production is Negatively IN VIVO Regulated by Extracellular Signal Regulated Kinase 5 (ERK5) YUEXIU WU, BIAO FENG, SHALI CHEN, SUBRATA CHAKRABARTI, London, ON, Canada Increased extracellular matrix protein production is a characteristic fea- Guided Audio Tour: Genetic and Human Metabolic Predictors of Diabetes ture of diabetic complications. Fibronectin (FN), a key extracellular matrix (Posters 1721-P to 1728-P), see page 17. protein is known to be upregulated in diabetes. ERK5 plays a critical role in cardiovascular development and in maintaining endothelial cell integrity. The aim of the study is to investigate the regulation of ERK5 signaling on & 1721-P glucose-induced FN overproduction.Human microvascular endothelial cells Mexican American Subjects With Impaired Fasting Glucose (IFG) were used. FN mRNA and protein levels were measured using ELISA and are Characterized by Hepatic and Adipocyte Insulin Resistance and real-time PCR respectively. Transforming growth factor beta 1(TGF`1) ex- Beta Cell Dysfunction pression and Smad2 proteins were investigated. Constitutively active MEK5 RUTH ARYA, ZANDRA PEREZ-CADENA, ANDREA HANSIS-DIARTE, DEIDRE WIN- (CAMEK5) adenovirus was transducted to upregulate ERK5 signaling. ERK5 NIER, LAUREN CORTEZ, RALPH DEFRONZO, DEVJIT TRIPATHY, CHRISTOPHER siRNA and dominant negative MEK5 (DNMEK5) transfections were used JENKINSON, San Antonio, TX to downregulate ERK5.Glucose caused a dose dependent increase in FN The aim of the current study was to characterize the metabolic defects production. Such increase was associated with upregulation of TGF`1 and associated with prediabetic states IFG and impaired glucose tolerance (IGT). Smad2 phosphorylation. ERK5 expression peaked at 24 hrs. Signifi cant de- We compared adipocyte, hepatic and whole body insulin resistance and beta crease of basal and glucose induced increased FN mRNA and protein levels cell function in subjects with normal glucose tolerance NGT n=36 age 46±2 were observed after CAMEK5 transduction. In contrast, ERK5 siRNA and BMI 30±1, IFG n=30 age 47±2 BMI 33±1, IGT n=20 age 49±3 BMI 34±1, IFG/ DNMEK5 treatment led to an increase of FN synthesis. Moreover, West- IGT n=36 age 49±3 BMI 34±1, T2D n=81 age 58±1 BMI 35±1). Indices of in- ern blot analysis showed that phosphorylated Smad2 was suppressed by sulin secretion and insulin sensitivity were derived from plasma glucose, CAMEK5 transduction with or without glucose treatment. On the other hand insulin and FFA concentrations during the OGTT and from hyperinsulinemic siERK5 transfection enhanced TGF`1mRNA expression. Furthermore, we in- euglycemic clamp (80/mU/m2/min) with indirect calorimetry and tritiated vestigated neurotrophins, eg. nerve growth factor (NGF) and brain-derived glucose infusion (non-diabetics, n=54) to measure hepatic glucose produc- neurotrophic factor (BNDF). Both are known upstream regulators of ERK5. tion. Adipocyte IR (AR) was the product of fasting FFA and fasting insulin. IFG The alterations of neurotrophins paralleled that of ERK5. Exogenous NGF subjects had similar whole body glucose uptake but higher hepatic insulin re- supplementation resulted in elevated phosphorylated and total ERK5 with or sistance (BGP x Fasting insulin) vs NGT (21.2±4 vs 7.6±1 mg/kg/min, p<0.05). without glucose treatment.Taken together, our experiments demonstrated a Whole body glucose disposal (skeletal muscle) was lower in subjects with novel mechanism of FN regulation under high glucose conditions. Decreased IFG/IGT primarily due to reduced non-oxidative glucose metabolism. Plasma ERK5 signaling contributes to glucose-induced FN overproduction. fasting FFA and AR progressively increased from NGT to IFG to IFG/IGT and Supported by: Canadian Diabetes Association DM. Adipocyte IR correlated with whole body glucose disposal (r=-0.621, p<0.005), hepatic insulin resistance (r=0.766, p<0.005), insulin secretion/ insulin resistance (disposition) index 6I0-120/6G0-120 X MI (r=-0.248, p=0.01) 1720-P and the non-oxidative glucose disposal during the insulin clamp (r=-0.361, Exenatide Ameliorates Insulin Resistance by Upregulating SIRT1 p=0.03). Compared to NGT subjects the disposition index (6I0-120/6G0-120 x MI) Expression of Adipose Tissue in db/db Mice was reduced by 18%, 68%, 80% in IFG, IGT, and combined IFG/IGT respec- ZONGLAN CHEN, HUIMIN GU, FEN XU, JINHUA YAN, HUA LIANG, JIANPING tively. In conclusion subjects with IFG are characterized by hepatic insulin WENG, Guangzhou, China resistance while those with IGT primarily have skeletal muscle insulin resis- Although Exenatide can improve insulin sensitivity of obesity and type 2 tance and are characterized by marked beta cell dysfunction. Therapeutic diabetes, the underlying mechanisms are still poorly understood. Growing interventions to preserve beta cell function should be started early. evidence suggests that SIRT1 has a positive role in the metabolic pathway through its direct or indirect involvement in insulin signaling. In this study, we investigated the regulation of Exenatide on SIRT1 expression in white adipose tissue of db/db mice. The 7-8 weeks male db/db mice and their & 1722-P heterozygous were divided into 3 groups of 10 animals each as follows: NC Insulin Sensitivity, Insulin Secretion and Disposition Index in Per- group (db/m mice, normal control), DM group (db/db mice), EX group (db/ sons With Normal and “Pre-Diabetic” HbA1c Levels: The Pathobiol- db mice treated with Exenatide 24nmol/kg/d for 8 weeks). Intraperitoneal ogy of Prediabetes in A Biracial Cohort (POP-ABC) Study insulin tolerance test (IPITT) indicated Exenatide could improve insulin sen- CHIMAROKE EDEOGA, SOTONTE EBENIBO, SAMUEL DAGOGO-JACK, Memphis, sitivity and lower fasting glucose levels signifi cantly in db/db mice. Western TN blotting analysis demonstrated that DM group had decreased expressions of An A1c range of 5.7-6.4% has been suggested for the diagnosis of predia- SIRT1, IRS1 and increased expression of p-JNK as compared with NC group. betes. In this report, we compared metabolic data in persons with normal All of these changes were attenuated or reversed when the diabetic mice (N=189) or “prediabetic”(N=98) status based on A1c. We studied 287 nondia- were treated with Exenatide. Our data suggested that Exenatide treatment betic adult offspring (147 black, 140 white) of type 2 diabetes (T2DM) par- ameliorated insulin resistance in db/db mice potentially through regulating ents enrolled in POP-ABC, a study of incident dysglycemia among offspring SIRT1-p-JNK-IRS1 axis. of T2DM parents. Their mean (+ SD) age was 44.2 + 10.6 y and BMI was 30.2 + 7.25 kg/m2. Baseline measurements included anthropometrics, 75-g OGTT and A1c level, followed by IVGTT and DEXA within 3 months of enrollment. Insulin action (M) was measured using euglycemic clamp, and beta-cell func- tion was assessed using acute insulin response (AIR) during IVGTT. The dis- Obesity position index (DI) was calculated as the product of AIR and M. Basal homeo- POSTERS stasis was assessed by calculating HOMA-IR and HOMA-B. Compared to the normal controls (A1c < 5.7%), subjects with “prediabetic”A1c levels (5.7- Integrated Physiology/ 6.4%) were older (47.9 + 9.2 (SD), P=0.0004), and had higher fasting glucose (92.2 + 6.45 vs. 90.2 + 7.25 mg/dl, P=0.011), BMI (31.5 +7.97 vs. 29.2 + 13.2 kg/m2, P=0.03), total body fat (P=0.02) and trunk fat mass (P=0.016). How- ever, there were no signifi cant differences between the two groups with regard to HOMA-IR, HOMA-B, AIR, M value or DI in African Americans or Supported by: Program for Changjiang Scholars and Innovative Research Team Caucasiand (Fig 1). We conclude that an A1c range of 5.7-6.4% is associated with increased adiposity, but does not predict established glucoregulatory impairments that enable distinction from persons with lower A1c values. ADA-Funded Research & Guided Audio Tour poster For author disclosure information, see page 797. A443 INTEGRATED PHYSIOLOGY—INSULINCATEGORY SECRETION IN VIVO false positive fi ndings. Fortyfi ve SNPs, selected to cover over 90% of com- mon genetic variability, were genotyped in 8 MODY (HNF4A, GCK, HNF1A, PDX1, HNF1B, NEUROD1, KLF11, CEL) and 2 neonatal diabetes (NDM) (KCNJ11, ABCC8) genes. Allelic variants of 4 SNPs (rs1303722 and rs882019 of GCK, rs7310409 of HNF1A and rs5219 of KCNJ11, the latter being a known type 2 diabetes risk variant) exerted independent signifi cant effects on DC of beta- cell function (p=0.007-0.03). Allelic variants of 5 other SNPs (rs2869084 and rs6031544 of HNF4A, rs10774580 of HNF1A, rs1801262 of NEUROD1, and rs7129639 of ABCC8) were found to infl uence signifi cantly PC of beta-cell function (p=0.001-0.04). Only 1 (rs6721191 of KLF11) out of 45 SNPs was asso- ciated to insulin sensitivity (p=0.047). In multivariate models, combining GCK, HNF1A and KCNJ11 SNPs accounted for ~2,5% of DC of beta-cell function, whereas combining HNF4A, HNF1A, NEUROD1 and ABCC8 SNPs accounted Supported by: NIH-NIDDK for ~3.6% of PC of beta-cell function. We conclude that common variability of MODY and NDM genes signifi cantly affects beta cell function in patients with type 2 diabetes, thereby potentially playing a role in the pathophysiol- & 1723-P ogy and/or the “metabolic prognosis” of the disease. Short Term Mild Hyperglycemia Improves Oral Glucose Disposal Supported by: European Foundation for the Study of Diabetes/Novartis Grant and Ƶ-Cell Function in Subjects With Impaired Glucose Tolerance (IGT) LORENA A. WRIGHT, KRISTINA M. UTZSCHNEIDER, JENNY TONG, SEDA SUVAG, & 1725-P STEVEN E. KAHN, Seattle, WA, Cincinatti, OH Mutations in ABCA1 and Enhanced Ƶ-cell Secretory Capacity in Hu- Mild 24 h hyperglycemia improves insulin sensitivity, `-cell function and mans: Preliminary Results glucose disposal in subjects with normal glucose tolerance.