Study Design of a Phase II Clinical Trial to Assess the Efficacy and Safety of Eperisone in Japanese Type 2 Diabetes Patients with Risk and Non-risk Alleles of CDKAL1

Genetic variation in Cdk5 Regulatory Associated Protein 1-Like 1 (CDKAL1) is associated with the development of type 2 diabetes (T2D). Dysfunction of CDKAL1 impairs the translation of proinsulin, which leads to glucose intolerance. Eperisone, an antispasmodic agent, has been shown to ameliorate glucose intolerance in Cdkal1-deficient mice. We have launched a phase II clinical study to investigate the potential anti-diabetic effect of eperisone in T2D patients carrying risk or non-risk alleles of CDKAL1. The primary endpoint is the change of hemoglobin A1c (HbA1c) levels. We also examined whether the efficacy of eperisone in T2D patients is associated with CDKAL1 activity

Mitochondrial dysfunction and increased reactive oxygen species impair insulin secretion in sphingomyelin synthase 1-null Mice

Sphingomyelin synthase 1 (SMS1) catalyzes the conversion of ceramide to sphingomyelin. Here, we generated and analyzed SMS1-null mice. SMS1-null mice exhibited moderate neonatal lethality, reduced body weight, and loss of fat tissues mass, suggesting that they might have metabolic abnormality. Indeed, analysis on glucose metabolism revealed that they showed severe deficiencies in insulin secretion. Isolated mutant islets exhibited severely impaired ability to release insulin, dependent on glucose stimuli. Further analysis indicated that mitochondria in mutant islet cells cannot up-regulate ATP production in response to glucose. We also observed additional mitochondrial abnormalities, such as hyperpolarized membrane potential and increased levels of reactive oxygen species (ROS) in mutant islets. Finally, when SMS1-null mice were treated with the anti-oxidant N-acetyl cysteine, we observed partial recovery of insulin secretion, indicating that ROS overproduction underlies pancreatic β-cell dysfunction in SMS1-null mice. Altogether, our data suggest that SMS1 is important for controlling ROS generation, and that SMS1 is required for normal mitochondrial function and insulin secretion in pancreatic β-cells.Masato Yano, Ken Watanabe, Tadashi Yamamoto, Kazutaka Ikeda, Takafumi Senokuchi, Meihong Lu, Tsuyoshi Kadomatsu, Hiroto Tsukano, Masahito Ikawa, Masaru Okabe, Shohei Yamaoka, Toshiro Okazaki, Hisanori Umehara, Tomomi Gotoh, Wen-Jie Song, Koichi Node, Ryo Taguchi, Kazuya Yamagata, Yuichi Oike, Mitochondrial Dysfunction and Increased Reactive Oxygen Species Impair Insulin Secretion in Sphingomyelin Synthase 1-null Mice, Journal of Biological Chemistry, Volume 286, Issue 5, 2011, Pages 3992-4002, ISSN 0021-9258, https://doi.org/10.1074/jbc.M110.179176

Hyperglycemia Induces Cellular Hypoxia through Production of Mitochondrial ROS Followed by Suppression of Aquaporin-1.

We previously proposed that hyperglycemia-induced mitochondrial reactive oxygen species (mtROS) generation is a key event in the development of diabetic complications. Interestingly, some common aspects exist between hyperglycemia and hypoxia-induced phenomena. Thus, hyperglycemia may induce cellular hypoxia, and this phenomenon may also be involved in the pathogenesis of diabetic complications. In endothelial cells (ECs), cellular hypoxia increased after incubation with high glucose (HG). A similar phenomenon was observed in glomeruli of diabetic mice. HG-induced cellular hypoxia was suppressed by mitochondria blockades or manganese superoxide dismutase (MnSOD) overexpression, which is a specific SOD for mtROS. Overexpression of MnSOD also increased the expression of aquaporin-1 (AQP1), a water and oxygen channel. AQP1 overexpression in ECs suppressed hyperglycemia-induced cellular hypoxia, endothelin-1 and fibronectin overproduction, and apoptosis. Therefore, hyperglycemia-induced cellular hypoxia and mtROS generation may promote hyperglycemic damage in a coordinated manner

Impact of tissue macrophage proliferation on peripheral and systemic insulin resistance in obese mice with diabetes

Introduction Obesity-related insulin resistance is a widely accepted pathophysiological feature in type 2 diabetes. Systemic metabolism and immunity are closely related, and obesity represents impaired immune function that predisposes individuals to systemic chronic inflammation. Increased macrophage infiltration and activation in peripheral insulin target tissues in obese subjects are strongly related to insulin resistance. Using a macrophage-specific proliferation inhibition mouse model (mac-p27Tg), we previously reported that suppressed plaque inflammation reduced atherosclerosis and improved plaque stabilization. However, the direct evidence that proliferating macrophages are responsible for inducing insulin resistance was not provided.Research design and methods The mac-p27Tg mice were fed a high-fat diet, and glucose metabolism, histological changes, macrophage polarization, and tissue functions were investigated to reveal the significance of tissue macrophage proliferation in insulin resistance and obesity.Results The mac-p27Tg mice showed improved glucose tolerance and insulin sensitivity, along with a decrease in the number and ratio of inflammatory macrophages. Obesity-induced inflammation and oxidative stress was attenuated in white adipose tissue, liver, and gastrocnemius. Histological changes related to insulin resistance, such as liver steatosis/fibrosis, adipocyte enlargement, and skeletal muscle fiber transformation to fast type, were ameliorated in mac-p27Tg mice. Serum tumor necrosis factor alpha and free fatty acid were decreased, which might partially impact improved insulin sensitivity and histological changes.Conclusions Macrophage proliferation in adipose tissue, liver, and skeletal muscle was involved in promoting the development of systemic insulin resistance. Controlling the number of tissue macrophages by inhibiting macrophage proliferation could be a therapeutic target for insulin resistance and type 2 diabetes

Impacts of the 2016 Kumamoto Earthquake on glycemic control in patients with diabetes

Abstract Aims/Introduction On April 14 and 16 2016, the Kumamoto area was severely damaged by several massive magnitude 7 class earthquakes. Materials and Methods To examine the effects of these earthquakes on glycemic control and stress factors, glycated hemoglobin, glycated albumin, other biochemical parameters, a self‐administered lifestyle‐associated questionnaire and disaster‐associated stress scores were analyzed. A total of 557 patients with diabetes were enrolled, and data were collected at 13 months before to 13 months after the earthquakes. Results In patients with type 1 diabetes and specific types of diabetes due to other causes, glycemic control was not altered during the observational period. This glycemic stability in type 1 diabetes might result from self‐management of insulin doses. In patients with type 2 diabetes, glycated hemoglobin decreased by 0.11% (from 7.33 to 7.22%) at 1–2 months after the earthquakes, and increased thereafter. The reduction of glycated hemoglobin after 1–2 months in type 2 diabetes was associated with ‘early restoration of lifelines’ and ‘sufficient sleep.’ The glycemic deterioration at a later stage was related to ‘shortage of antidiabetic agents,’ ‘insufficient amount of food,’ ‘largely destroyed houses’ and ‘changes in working environments.’ Disaster‐associated stress levels were positively correlated with ‘age,’ ‘delayed restoration of lifelines,’ ‘self‐management of antidiabetic agents’ and ‘increased amount of physical activity/exercise,’ and negatively associated with ‘early restoration of lifelines’ and ‘sufficient sleep.’ Conclusions Glycemic control, associated factors and stress levels are altered in chronological order. Post‐disaster diabetic medical care must consider these corresponding points in accordance with the time‐period

Role of Sirt7 in Neointimal Formation

Background: Sirt7 is a recently identified sirtuin and has important roles in various pathological conditions, including cancer progression and metabolic disorders. It has previously been reported that Sirt7 is a key molecule in acute myocardial wound healing and pressure overload-induced cardiac hypertrophy. In this study, the role of Sirt7 in neointimal formation after vascular injury is investigated. Methods and Results: Systemic (Sirt7−/−) and smooth muscle cell-specific Sirt7-deficient mice were subjected to femoral artery wire injury. Primary vascular smooth muscle cells (VSMCs) were isolated from the aorta of wild type (WT) and Sirt7−/−mice and their capacity for cell proliferation and migration was compared. Sirt7 expression was increased in vascular tissue at the sites of injury. Sirt7−/−mice demonstrated significant reduction in neointimal formation compared to WT mice. In vitro, Sirt7 deficiency attenuated the proliferation of serum-induced VSMCs. Serum stimulation-induced upregulation of cyclins and cyclin-dependent-kinase 2 (CDK2) was significantly attenuated in VSMCs of Sirt7−/−compared with WT mice. These changes were accompanied by enhanced expression of the microRNA 290-295 cluster, the translational negative regulator of CDK2, in VSMCs of Sirt7−/−mice. It was confirmed that smooth muscle cell-specific Sirt7-deficient mice showed significant reduction in neointima compared with control mice. Conclusions: Sirt7 deficiency attenuates neointimal formation after vascular injury. Given the predominant role in vascular neointimal formation, Sirt7 is a potentially suitable target for treatment of vascular diseases

Identification of microRNA that represses IRS-1 expression in liver.

MicroRNAs (miRNAs) are short, non-coding RNAs that post-transcriptionally regulate gene expression and have been shown to participate in almost every cellular process. Several miRNAs have recently been implicated in glucose metabolism, but the roles of miRNAs in insulin-resistant conditions, such as obesity or type 2 diabetes, are largely unknown. Herein, we focused on miR-222, the expression of which was increased in the livers of high fat/high sucrose diet-fed mice injected with gold thioglucose (G+HFHSD). Overexpression of miR-222 in primary mouse hepatocytes attenuated Akt phosphorylation induced by insulin, indicating that miR-222 negatively regulates insulin signaling. As per in silico analysis, miR-222 potentially binds to the 3' untranslated region (3' UTR) of the IRS-1 gene, a key insulin signaling molecule. In fact, IRS-1 protein expression was decreased in the livers of G+HFHSD-fed mice. We further confirmed a direct interaction between miR-222 and the 3' UTR of IRS-1 via luciferase assays. Our findings suggest that up-regulation of miR-222 followed by reduction in IRS-1 expression may be a viable mechanism of insulin resistance in the liver