The influence of β-cell function on cardiovascular autonomic neuropathy (CAN), an important diabetes-related complication, is still unclear. In this study, we aimed to investigate the association between residual β-cell function and CAN in patients newly diagnosed with type 2 diabetes. We enrolled 90 newly-diagnosed type 2 diabetic patients and 37 participants with normal glucose tolerance as controls. The patients were divided into a CAN+ group (diabetic patients with CAN, n = 20) and a CAN- group (diabetic patients without CAN, n = 70) according to the standard Ewing battery of tests. Fasting and postprandial plasma glucose, insulin, and C-peptide were measured. Homeostasis model assessment-beta cells (HOMA-B) and HOMA-insulin resistance (IR) were calculated. The prevalence of CAN in this population was 22.2%. Compared with the CAN- group, the CAN+ group had significantly lower fasting plasma insulin (6.60 ± 4.39 vs 10.45 ± 7.82 μ/L, P = 0.029), fasting C-peptide (0.51 ± 0.20 vs 0.82 ± 0.51 nmol/L, P = 0.004), and HOMA-B (21.44 ± 17.06 vs 44.17 ± 38.49, P = 0.002). Fasting C-peptide was correlated with the Valsalva ratio (r = 0.24, P = 0.043) and the 30:15 test (r = 0.26, P = 0.023). Further analysis showed that fasting C-peptide (OR: 0.041, 95% CI 0.003-0.501, P = 0.012) and HOMA-B (OR: 0.965, 95% CI 0.934-0.996, P = 0.028) were independently associated with cardiovascular autonomic nerve function in this population. The patients with fasting C-peptide values < 0.67 nmol/L were more likely to have CAN than those with C-peptide levels ≥0.67 nmol/L (OR: 6.00, 95% CI 1.815-19.830, P = 0.003). A high prevalence of CAN was found in patients with newly-diagnosed type 2 diabetes. Decreased β-cell function was closely associated with CAN in this population.
Adult ; Asian Continental Ancestry Group ; Blood Glucose ; analysis ; Diabetes Mellitus, Type 2 ; complications ; metabolism ; Diabetic Neuropathies ; etiology ; Fasting ; physiology ; Female ; Glucose ; metabolism ; Humans ; Insulin ; metabolism ; Insulin Resistance ; physiology ; Insulin-Secreting Cells ; metabolism ; Male ; Middle Aged

Mammalian pancreatic β-cells play a pivotal role in development and glucose homeostasis through the production and secretion of insulin. Functional failure or decrease in β-cell number leads to type 2 diabetes (T2D). Despite the physiological importance of β-cells, the viability of β-cells is often challenged mainly due to its poor ability to adapt to their changing microenvironment. One of the factors that negatively affect β-cell viability is high concentration of free fatty acids (FFAs) such as palmitate. In this work, we demonstrated that Yes-associated protein (Yap1) is activated when β-cells are treated with palmitate. Our loss- and gain-of-function analyses using rodent insulinoma cell lines revealed that Yap1 suppresses palmitate-induced apoptosis in β-cells without regulating their proliferation. We also found that upon palmitate treatment, re-arrangement of F-actin mediates Yap1 activation. Palmitate treatment increases expression of one of the Yap1 target genes, connective tissue growth factor (CTGF). Our gain-of-function analysis with CTGF suggests CTGF may be the downstream factor of Yap1 in the protective mechanism against FFA-induced apoptosis.
Actins ; metabolism ; Adaptor Proteins, Signal Transducing ; antagonists & inhibitors ; genetics ; metabolism ; Animals ; Apoptosis ; drug effects ; physiology ; Bridged Bicyclo Compounds, Heterocyclic ; pharmacology ; Cell Line, Tumor ; Connective Tissue Growth Factor ; genetics ; metabolism ; pharmacology ; Cytochalasin D ; pharmacology ; Fatty Acids, Nonesterified ; pharmacology ; HEK293 Cells ; Humans ; Immunohistochemistry ; Insulin-Secreting Cells ; cytology ; drug effects ; metabolism ; Mice ; Microscopy, Fluorescence ; Palmitic Acid ; pharmacology ; Phosphoproteins ; antagonists & inhibitors ; genetics ; metabolism ; RNA Interference ; RNA, Small Interfering ; metabolism ; Rats ; Recombinant Proteins ; genetics ; metabolism ; pharmacology ; Thiazolidines ; pharmacology

Non-coding RNA is a kind of non-coding protein RNA which is widely present in most of the organisms. Non-coding RNA plays key roles in the embryonic development,cell fate determination,and growth control in the living organisms. MicroRNA and long non-coding RNA involve in differentiation of endocrine cell,insulin gene expression and secretion,and insulin resistance,which are closely associated with diabetes.
Cell Differentiation ; Diabetes Mellitus ; Gene Expression ; physiology ; Gene Expression Profiling ; Gene Expression Regulation, Developmental ; Humans ; Insulin ; Insulin-Secreting Cells ; Islets of Langerhans ; growth & development ; metabolism ; MicroRNAs ; RNA, Untranslated ; metabolism

Type 1 diabetes is an autoimmune disease caused by permanent destruction of insulin-producing pancreatic beta cells and requires lifelong exogenous insulin therapy. Recently, islet transplantation has been developed, and although there have been significant advances, this approach is not widely used clinically due to the poor survival rate of the engrafted islets. We hypothesized that improving survival of engrafted islets through ex vivo genetic engineering could be a novel strategy for successful islet transplantation. We transduced islets with adenoviruses expressing betacellulin, an epidermal growth factor receptor ligand, which promotes beta-cell growth and differentiation, and transplanted these islets under the renal capsule of streptozotocin-induced diabetic mice. Transplantation with betacellulin-transduced islets resulted in prolonged normoglycemia and improved glucose tolerance compared with those of control virus-transduced islets. In addition, increased microvascular density was evident in the implanted islets, concomitant with increased endothelial von Willebrand factor immunoreactivity. Finally, cultured islets transduced with betacellulin displayed increased proliferation, reduced apoptosis and enhanced glucose-stimulated insulin secretion in the presence of cytokines. These experiments suggest that transplantation with betacellulin-transduced islets extends islet survival and preserves functional islet mass, leading to a therapeutic benefit in type 1 diabetes.
Animals ; Apoptosis ; Betacellulin ; Cell Proliferation ; Diabetes Mellitus, Experimental/*surgery ; Glucose Intolerance/*surgery ; Humans ; Insulin-Secreting Cells/*metabolism/physiology ; Intercellular Signaling Peptides and Proteins/genetics/*metabolism ; *Islets of Langerhans Transplantation ; Mice ; Mice, Inbred C57BL ; Rats

BACKGROUNDIncreasingly, evidence from population, clinic-based and laboratory studies supports an independent association between obstructive sleep apnea syndrome (OSAS) and an increased risk of type 2 diabetes; however, this observation has yet to be replicated in China and the potential mechanisms that link these two conditions are not clear.

METHODSA total of 179 Han Chinese subjects were enrolled in this study. All subjects underwent polysomnography, the oral glucose tolerance-insulin releasing test (OGTT-IRT) and serum HbA(1)c measurement. Indexes including homeostasis model assessment-IR (HOMA-IR), Matsuda index, HOMA-β, early phase insulinogenic index (ΔI(30)/ΔG(30)), AUC-I(180) and oral disposition index (DIo) were calculated for the assessment of insulin resistance and pancreatic β-cell function.

RESULTSBased on OGTT, 25.4%, 44.6% and 54.5% subjects were diagnosed having glucose metabolic disorders respectively in control, mild to moderate and severe OSAS groups (P < 0.05). Serum HbA(1)c levels were highest in subjects with severe OSAS (P < 0.05). In contrast, compared with normal subjects, HOMA-β, ΔI(30)/Δ(G30) and DIO were lower in severe OSAS group (P < 0.05). In stepwise multiple linear regressions, 0-min glucose and HbA(1)c were positively correlated with the percentage of total sleep time below an oxyhemoglobin saturation of 90% (T90) (Beta = 0.215 and 0.368, P < 0.05); 30-min and 60-min glucose was negatively correlated with the lowest SpOO(2) (LSpO(2)) (Beta = -0.214 and -0.241, P < 0.05). HOMA-β and DI(O) were negatively correlated with T90 (Beta = -0.153 and -0.169, P < 0.05) while body mass index (BMI) was the only determinant of HOMA-IR and Matsuda index.

CONCLUSIONSOSAS is associated with impairment in glucose tolerance and pancreatic β-cell function in Han Chinese subjects while insulin sensitivity is mainly determined by obesity.

Adolescent ; Adult ; Aged ; Female ; Glucose ; metabolism ; Glucose Tolerance Test ; Glycated Hemoglobin A ; analysis ; Humans ; Insulin Resistance ; Insulin-Secreting Cells ; physiology ; Male ; Middle Aged ; Polysomnography ; Sleep Apnea, Obstructive ; metabolism

BACKGROUNDGrowing evidence from population and clinic based studies showed that obstructive sleep apnea (OSA) and its characterizing chronic intermittent hypoxia (IH) were independently associated with the development of type 2 diabetes mellitus. However, the pathogenesis by which OSA induces glucose metabolic disorders is not clear. We determined changes in pancreatic β cell mass and the mammalian target of rapamycin (mTOR)/hypoxia inducible factor 1 (HIF-1)/vascular endothelial growth factor A (VEGF-A) pathway following IH exposure.

METHODSA controlled gas delivery system regulated the flow of nitrogen and oxygen into a customized cage housing mice during the experiment. Twenty-four male wild C57BL/6J mice were either exposed to IH (n = 12) or intermittent air as a control (n = 12) for 56 days. Mice were anaesthetized and sacrificed after exposure, pancreas samples were dissected for immunofluorescent staining. Insulin and DAPI staining labelled islet β cells. Insulin positive area and β cell number per islet were measured. P-S6, HIF-1α and VEGF-A staining were performed to detect the activation of mTOR/HIF-1/VEGF-A pathway.

RESULTSAfter eight weeks of IH exposure, insulin positive area increased by an average of 18.5% (P < 0.05). The β cell number per islet increased (92 vs. 55, respectively for IH and the control groups, P < 0.05) with no change in the size of individual β cells. Islet expression of HIF-1α and VEGF-A were higher in IH group than control group, and percentage of p-S6 positive β cell also increased after IH exposure (16.8% vs. 4.6% respectively for IH and the control groups, P < 0.05).

CONCLUSIONThe number of pancreatic β cells increased as did the activity of the mTOR/HIF-1/VEGF-A pathway after exposure to IH.

Animals ; Hypoxia ; pathology ; Hypoxia-Inducible Factor 1 ; physiology ; Insulin-Secreting Cells ; metabolism ; pathology ; Male ; Mice ; Mice, Inbred C57BL ; Signal Transduction ; TOR Serine-Threonine Kinases ; physiology ; Vascular Endothelial Growth Factor A ; physiology

PURPOSE: Although the presence of cannabinoid type 1 (CB1) receptor in islets has been reported, the major contributor to the protective effect of rimonabant on islet morphology is unknown. We determined whether the protective effect of rimonabant on pancreatic islet morphology is valid in established diabetes and also whether any effect was independent of decreased food intake. MATERIALS AND METHODS: After diabetes was confirmed, Otsuka Long-Evans Tokushima Fatty rats, aged 32 weeks, were treated with rimonabant (30 mg/kg/d, rimonabant group) for 6 weeks. Metabolic profiles and islet morphology of rats treated with rimonabant were compared with those of controls without treatment (control group), a pair-fed control group, and rats treated with rosiglitazone (4 mg/kg/d, rosiglitazone group). RESULTS: Compared to the control group, rats treated with rimonabant exhibited reduced glycated albumin levels (p<0.001), islet fibrosis (p<0.01), and improved glucose tolerance (p<0.05), with no differences from the pair-fed control group. The retroperitoneal adipose tissue mass was lower in the rimonabant group than those of the pair-fed control and rosiglitazone groups (p<0.05). Rimonabant, pair-fed control, and rosiglitazone groups showed decreased insulin resistance and increased adiponectin, with no differences between the rimonabant and pair-fed control groups. CONCLUSION: Rimonabant had a protective effect on islet morphology in vivo even in established diabetes. However, the protective effect was also reproduced by pair-feeding. Thus, the results of this study did not support the significance of islet CB1 receptors in islet protection with rimonabant in established obesity-associated type 2 diabetes.
Adiponectin/metabolism ; Adiposity/drug effects ; Animals ; Cell Proliferation/drug effects ; Diabetes Mellitus, Type 2/diet therapy/*drug therapy ; Eating/*drug effects ; Glucose Intolerance/diet therapy/*drug therapy ; Insulin Resistance ; Insulin-Secreting Cells/*drug effects/pathology ; Male ; Piperidines/adverse effects/*therapeutic use ; Pyrazoles/adverse effects/*therapeutic use ; Rats ; Rats, Inbred OLETF ; Receptor, Cannabinoid, CB1/physiology ; Thiazolidinediones/*therapeutic use

BACKGROUNDAbnormal insulin secretion of pancreatic beta cells is now regarded as the more primary defect than the insulin function in the etiology of type 2 diabetes. Previous studies found impaired mitochondrial function and impaired Ca(2+) influx in beta cells in diabetic patients and animal models, suggesting a role for these processes in proper insulin secretion. The aim of this study was to investigate the detailed relationship of mitochondrial function, Ca(2+) influx, and defective insulin secretion.

METHODSWe investigated mitochondrial function and morphology in pancreatic beta cell of diabetic KK-Ay mice and C57BL/6J mice. Two types of Ca(2+) channel activities, L-type and store-operated Ca(2+) (SOC), were evaluated using whole-cell patch-clamp recording. The glucose induced Ca(2+) influx was measured by a non-invasive micro-test technique (NMT).

RESULTSMitochondria in KK-Ay mice pancreatic beta cells were swollen with disordered cristae, and mitochondrial function decreased compared with C57BL/6J mice. Ca(2+) channel activity was increased and glucose induced Ca(2+) influx was impaired, but could be recovered by genipin.

CONCLUSIONDefective mitochondrial function in diabetic mice pancreatic beta cells is a key cause of abnormal insulin secretion by altering Ca(2+) influx, but not via Ca(2+) channel activity.

Animals ; Calcium ; metabolism ; Diabetes Mellitus ; metabolism ; physiopathology ; Electrophysiology ; Insulin ; secretion ; Insulin-Secreting Cells ; metabolism ; Male ; Membrane Potential, Mitochondrial ; physiology ; Mice ; Mice, Inbred C57BL ; Mitochondria ; metabolism

OBJECTIVETo investigate the differentiation of human amniotic epithelial cells (hAECs) into insulin secreting cells (ISCs) in vitro.

METHODSThe hAECs were isolated from human amnion by trypsin digestion, and the phenotype of the isolated cells were identified by flow cytometry and immunocytochemical staining. The hAECs at passage 3 were treated with nicotinamide and N2 supplement to investigate their differentiation into ISCs. At different times after differentiation, the expression of insulin and beta2 microglobulin (beta2-MG) was determined by immunocytochemical staining, while the content of insulin in supernatant from cultured hAECs was detected by radioimmunoassay and the expressions of insulin, pancreatic and duodenal homeobox factor-1 (PDX-1) mRNA were detected by reverse transcriptase-polymerase chain reaction (RT-PCR).

RESULTS(1) hAECs expressed high percent of CD29, CD73, CD166 and CK19. (2) At 7, 14 and 21 days, the percentages of insulin-positive cells in induced groups were 74.00% +/- 1.73%, 75.33% +/- 1.15% (see symbol) 75.67% +/- 0.58% respectively, which were negative in control groups. (3) At 7, 14 and 21 days, contents of insulin in supernatant from induced groups were (328.47 +/- 3.22) microIU/ml, (332.26 +/- 1.22) microIU/ml and (329.68 +/- 2.57) microIU/ml respectively, they were significantly higher than those in control groups (All P < 0.01). (4) PDX-1 mRNA and beta2-MG were expressed before and after the induction of hAECs, but insulin mRNA was expressed only in the induced groups.

CONCLUSIONhAECs can differentiate into ISCs, having the potential application for therapy of type I diabetes.

Amnion ; cytology ; Cell Culture Techniques ; Cell Differentiation ; physiology ; Cells, Cultured ; Epithelial Cells ; cytology ; Flow Cytometry ; Homeodomain Proteins ; metabolism ; Humans ; Insulin ; metabolism ; Insulin-Secreting Cells ; cytology ; RNA, Messenger ; genetics ; Trans-Activators ; metabolism ; beta 2-Microglobulin ; metabolism

This study aimed to determine whether taurine supplementation improves metabolic disturbances and diabetic complications in an animal model for type 2 diabetes. We investigated whether taurine has therapeutic effects on glucose metabolism, lipid metabolism, and diabetic complications in Otsuka Long-Evans Tokushima fatty (OLETF) rats with long-term duration of diabetes. Fourteen 50-week-old OLETF rats with chronic diabetes were fed a diet supplemented with taurine (2%) or a non-supplemented control diet for 12 weeks. Taurine reduced blood glucose levels over 12 weeks, and improved OGTT outcomes at 6 weeks after taurine supplementation, in OLETF rats. Taurine significantly reduced insulin resistance but did not improve beta-cell function or islet mass. After 12 weeks, taurine significantly decreased serum levels of lipids such as triglyceride, cholesterol, high density lipoprotein cholesterol, and low density lipoprotein cholesterol. Taurine significantly reduced serum leptin, but not adiponectin levels. However, taurine had no therapeutic effect on damaged tissues. Taurine ameliorated hyperglycemia and dyslipidemia, at least in part, by improving insulin sensitivity and leptin modulation in OLETF rats with long-term diabetes. Additional study is needed to investigate whether taurine has the same beneficial effects in human diabetic patients.
Adipokines/blood ; Animals ; Blood Glucose ; Diabetes Mellitus, Type 2/drug therapy ; Dietary Supplements ; Dyslipidemias/blood/*drug therapy ; Glucose Tolerance Test ; Hyperglycemia/blood/*drug therapy ; Hypoglycemic Agents/administration & dosage/*pharmacology ; Hypolipidemic Agents/administration & dosage/*pharmacology ; Insulin/physiology/secretion ; Insulin Resistance ; Insulin-Secreting Cells/physiology/secretion ; Leptin/*blood ; Lipid Metabolism/drug effects ; Lipids/blood ; Male ; Organ Specificity ; Rats ; Rats, Long-Evans ; Taurine/administration & dosage/*pharmacology