Arsenic exposure and calpain-10 polymorphisms impair the function of pancreatic beta-cells in humans: a pilot study of risk factors for T2DM

Down-regulation of O-GlcNAcylation alleviates insulin signaling pathway impairment following arsenic exposure via suppressing the AMPK/mTOR-autophagy pathway

Impairment of the insulin signaling pathway is a key contributor to insulin resistance under arsenic exposure. Specifically, O-GlcNAcylation, an important post-translational modification, plays a crucial role in insulin resistance. Nevertheless, the concrete effect and mechanism of O-GlcNAcylation in arsenic-induced impairment of the insulin signaling pathway remain elusive. Herein, C57BL/6 mice were continuously fed arsenic-containing food, with a total arsenic concentration of 30 mg/kg. We observed that the IRS/Akt/GSK-3β insulin signaling pathway was impaired, and autophagy was activated in mouse livers and HepG2 cells exposed to arsenic. Additionally, O-GlcNAcylation expression in mouse livers and HepG2 cells was elevated, and the key O-GlcNAcylation homeostasis enzyme, O-GlcNAc transferase (OGT), was upregulated. In vitro, non-targeted metabolomic analysis showed that metabolic disorder was induced, and inhibition of O-GlcNAcylation restored the metabolic profile of HepG2 cells exposed to arsenic. In addition, we found that the compromised insulin signaling pathway was dependent on AMPK activation. Inhibition of AMPK mitigated autophagy activation and impairment of insulin signaling pathway under arsenic exposure. Furthermore, down-regulation of O-GlcNAcylation inhibited AMPK activation, thereby suppressing autophagy activation, and improving the impaired insulin signaling pathway. Collectively, our findings indicate that arsenic can impair the insulin signaling pathway by regulating O-GlcNAcylation homeostasis. Importantly, O-GlcNAcylation inhibition alleviated the impaired insulin signaling pathway by suppressing the AMPK/mTOR-autophagy pathway. This indicates that regulating O-GlcNAcylation may be a potential intervention for the impaired insulin signaling pathway induced by arsenic.

Glycemic Changes Related to Arsenic Exposure: An Overview of Animal and Human Studies

BACKGROUND

Arsenic (As) is a risk factor associated with glycemic alterations. However, the mechanisms of action and metabolic aspects associated with changes in glycemic profiles have not yet been completely elucidated. Therefore, in this review, we aimed to investigate the metabolic aspects of As and its mechanism of action associated with glycemic changes.

METHODS

We searched the PubMed (MEDLINE) and Google Scholar databases for relevant articles published in English. A combination of free text and medical subject heading keywords and search terms was used to construct search equations. The search yielded 466 articles; however, only 50 were included in the review.

RESULTS

We observed that the relationship between As exposure and glycemic alterations in humans may be associated with sex, smoking status, body mass index, age, occupation, and genetic factors. The main mechanisms of action associated with changes induced by exposure to As in the glycemic profile identified in animals are increased oxidative stress, reduced expression of glucose transporter type 4, induction of inflammatory factor expression and dysfunction of pancreatic β cells.

CONCLUSIONS

Therefore, As exposure may be associated with glycemic alterations according to inter-individual differences.

Arsenic in Drinking Water and Diabetes

Arsenic is ubiquitous in soil and water environments and is consistently at the top of the Agency for Toxic Substances Disease Registry (ATSDR) substance priority list. It has been shown to induce toxicity even at low levels of exposure. One of the major routes of exposure to arsenic is through drinking water. This review presents current information related to the distribution of arsenic in the environment, the resultant impacts on human health, especially related to diabetes, which is one of the most prevalent chronic diseases, regulation of arsenic in drinking water, and approaches for treatment of arsenic in drinking water for both public utilities and private wells. Taken together, this information points out the existing challenges to understanding both the complex health impacts of arsenic and to implementing the treatment strategies needed to effectively reduce arsenic exposure at different scales.

In vitro toxic interaction of arsenic and hyperglycemia in mitochondria: an important implication of increased vulnerability in pre-diabetics

Environmental pollutants and lifestyle both contribute to the rapidly increasing prevalence of type 2 diabetes mellitus (T2DM) worldwide. Evidence suggests that exposure to environmental contaminants such as arsenic is associated with impaired glucose metabolism and insulin signaling. In the present study, isolated rat liver mitochondria (1 mg/ml) were co-exposed to low concentration of arsenic trioxide (ATO) ( IC₂₅ = 40 µM) and hyperglycemic condition (20, 40, 80, 160 mM glucose or 20, 40, 80, 160 mM pyruvate (PYR)). Mitochondrial dehydrogenase activity (complex II), glutathione content (GSH), reactive oxygen species (ROS), lipid peroxidation, mitochondrial membrane potential (ΔΨ), and mitochondrial swelling were then evaluated in the presence of ATO 40 µM and PYR 40 mM. Unexpectedly, glucose alone (20, 40, 80, 160 mM) had no toxic effect on mitochondria, even at very high concentrations and even when combined with ATO. Interestingly, PYR at low concentrations (≤ 10 mM) has a protective effect on mitochondria, but at higher concentrations (≥ 40 mM) with ATO, it decreased the complex II activity and increased mitochondrial ROS production, lipid peroxidation, GSH depletion, mitochondrial membrane damage, and swelling (p < 0.05). In conclusion, PYR but not glucose increased ATO mitochondrial toxicity even at low concentrations. These results suggest that pre-diabetics with non-clinical hyperglycemia, who are inevitably exposed to low concentrations of arsenic through food and water, may develop mitochondrial dysfunction that accelerates their progression to diabetes over time.

Arsenic exposure during pregnancy and postpartum maternal glucose tolerance: evidence from Bangladesh

BACKGROUND

Arsenic exposure has been associated with gestational diabetes mellitus. However, the extent to which arsenic exposure during pregnancy is associated with postpartum glucose intolerance is unknown.

METHODS

We studied 323 women in Bangladesh. We assessed arsenic exposure in early pregnancy via toenail and water samples. We measured fasting glucose and insulin in serum at a mean (SD) of 4.0 (3.5) weeks post-delivery. We ran covariate-adjusted, linear regression models to examine associations of arsenic concentrations with HOMA-IR, a marker of insulin resistance, and HOMA-β, a marker of beta cell function.

RESULTS

Median (IQR) arsenic concentration was 0.45 (0.67) μg/g in toenails and 2.0 (6.5) μg/L in drinking water. Arsenic concentrations during pregnancy were not associated with insulin resistance or beta cell function postpartum. HOMA-IR was 0.07% (- 3.13, 3.37) higher and HOMA-β was 0.96% (- 3.83, 1.99) lower per IQR increment in toenail arsenic, but effect estimates were small and confidence intervals crossed the null.

CONCLUSIONS

Although arsenic exposure during pregnancy has been consistently associated with gestational diabetes mellitus, we found no clear evidence for an adverse effect on postpartum insulin resistance or beta cell function.

Dietary Selenium Deficiency Partially Mimics the Metabolic Effects of Arsenic

Chronic arsenic exposure via drinking water is associated with diabetes in human pop-ulations throughout the world. Arsenic is believed to exert its diabetogenic effects via multiple mechanisms, including alterations to insulin secretion and insulin sensitivity. In the past, acute arsenicosis has been thought to be partially treatable with selenium supplementation, though a potential interaction between selenium and arsenic had not been evaluated under longer-term exposure models. The purpose of the present study was to explore whether selenium status may augment arsenic's effects during chronic arsenic exposure. To test this possibility, mice were exposed to arsenic in their drinking water and provided ad libitum access to either a diet replete with selenium (Control) or deficient in selenium (SelD). Arsenic significantly improved glucose tolerance and decreased insulin secretion and β-cell function in vivo. Dietary selenium deficiency resulted in similar effects on glucose tolerance and insulin secretion, with significant interactions between arsenic and dietary conditions in select insulin-related parameters. The findings of this study highlight the complexity of arsenic's metabolic effects and suggest that selenium deficiency may interact with arsenic exposure on β-cell-related physiological parameters.

Health effects of arsenic exposure in Latin America: An overview of the past eight years of research

Studies conducted over the past eight years in Latin America (LA) have continued to produce new knowledge regarding health impacts of arsenic (As) in drinking water. We conducted a systematic review of 92 peer-reviewed English articles published between 2011 and 2018 to expand our understanding on these health effects. Majority of the LA studies on As have been conducted in Chile and Mexico. Additional data have emerged from As-exposed populations in Argentina, Bolivia, Brazil, Colombia, Ecuador, and Uruguay. The present review has documented recent data on the biomarkers of As exposure, genetic susceptibility and genotoxicity, and risk assessment to further characterize the health effects and exposed populations. Some recent findings on the associations of As with bladder and lung cancers, reproductive outcomes, and declined cognitive performance have been consistent with what we reported in our previous systematic review article. We have found highly convincing evidence of in utero As exposure as a significant risk factor for several health outcomes, particularly for bladder cancer, even at moderate level. New data have emerged regarding the associations of As with breast and laryngeal cancers as well as type 2 diabetes. We observed early life As exposure to be associated with kidney injury, carotid intima-media thickness, and various pulmonary outcomes in children. Other childhood effects such as low birth weight, low gestational age, anemia, increased apoptosis, and decreased cognitive functions were also reported. Studies identified genetic variants of As methyltransferase that could determine susceptibility to As related health outcomes. Arsenic-induced DNA damage and alteration of gene and protein expression have also been reported. While the scope of research is still vast, the substantial work done on As exposure and its health effects in LA will help direct further large-scale studies for more comprehensive knowledge and plan appropriate mitigation strategies.

Taurine rescues the arsenic-induced injury in the pancreas of rat offsprings and in the INS-1 cells

Arsenic was an established carcinogen and toxicant, occurring in drinking water and food. Arsenic was increasingly being blamed as a risk factor for diabetes mellitus. Recent studies have found that arsenic could induce the generation of reactive oxygen species (ROS) and mitochondria were the major targets of ROS. Damage mitochondria could be removed by mitophagy and mitophagy played a defensive role against cellular apoptosis. To investigate whether the arsenic could induce the injury in mitochondria, we treated Wistar rat offsprings and INS-1 cells with As2O3 and sodium arsenite, respectively. Our results showed that arsenic induced the generation of ROS in both rat offsprings' pancreas and INS-1 cells. The generation of ROS induced by arsenic could inhibit the expression of PPARγ. PPARγ is a major impact on mitochondrial function. The inhibition of PPARγ induced the reduction of PINK1 signaling and the upregulation of Bax. PINK1 signaling was one of the classical pathways of mitophagy. The inhibition of mitophagy induced the activation of apoptosis both in rat offsprings' pancreas and INS-1 cells. After treated with Rosiglitazone (RGS, PPARγ receptor agonist), PPARγ was rescued, the expression of PINK1 significantly increasing and the apoptosis was restrained. We used Taurine (Tau) as the protective agent both in rat offsprings' pancreas and INS-1 cells, after treated with Tau, the production of ROS was decreased significantly and the downgrade of PPARγ was rescued.

Taurine improves low-level inorganic arsenic-induced insulin resistance by activating PPARγ-mTORC2 signalling and inhibiting hepatic autophagy

Inorganic arsenic (iAs) is reportedly associated with the increased incidence of type 2 diabetes in the population. Here, we found that iAs exposure significantly decreased the expression of glycolytic genes and glycogen content and increased gluconeogenesis gene levels in C57/BL6J mice. The expression of peroxisome proliferator-activated receptor γ (PPARγ), and mechanistic target of rapamycin complex 2 (mTORC2) were decreased in the livers of iAs-treated mice. Furthermore, in iAs-treated HepG2 cells, we found that PPARγ agonist rosiglitazone (RGS) increased the expression of mTORC2, inhibited autophagy, and improved glucose metabolism. mTORC2 agonist palmitic acid inhibited autophagy and improved glucose metabolism as well as the autophagosome formation inhibitor 3-methyladenine. Taurine, a natural compound, reversed impaired glucose metabolism and decreased expression of PPARγ and mTORC2 induced by iAs in mice liver and HepG2 cells. These data indicated that taurine administration could ameliorate iAs-induced insulin resistance through activating PPARγ-mTORC2 signalling and subsequently inhibiting hepatic autophagy.

Exposure to arsenic in tap water and gestational diabetes: A French semi-ecological study

INTRODUCTION

The increase in the prevalence of gestational diabetes mellitus (GDM) and its consequences for mother and children prompts research on their risk factors including environmental factors. Studies on exposure to arsenic (As) in tap water and the risk of GDM have not provided conclusive evidence, particularly when levels of exposure were low (from 10 to 50µg As/L). The main objective of this study was to assess the association between exposure to As in tap water and the risk of GDM.

METHODS

A semi-ecological study was conducted from births recorded at the University Hospital of Clermont-Ferrand, France, in 2003, 2006 and 2010. Individual medical/obstetric data were available. As exposure was estimated from the concentrations of As measured during sanitary control of tap water supplied in the mothers' commune of residence (aggregate data). French guidelines for As in tap water were used to identify groups potentially exposed, designated "As +" (≥ 10µg As/L) and "As -" (< 10µg As/L). Multivariate logistic regression analysis was performed.

RESULTS

5053 women (5.7% with a GDM) were included. Overall, women in the As + group had a higher risk of GDM than those in the As - group (adjusted OR = 1.62; 95%CI: 1.01-2.53). Stratified analysis of pre-pregnancy body mass index (BMI) showed a positive association only for obese or overweight women (adjusted OR = 2.30; 95%CI: 1.13-4.50).

CONCLUSION

This French semi-ecological study provides additional arguments for an association between As exposure and the risk of GDM in particular in a context of low exposure. Further studies are needed to assess a potential interaction between As exposure and body mass index.

Arsenite and methylarsonite inhibit mitochondrial metabolism and glucose-stimulated insulin secretion in INS-1 832/13 β cells

Growing evidence suggests that exposure to environmental contaminants contributes to the current diabetes epidemic. Inorganic arsenic (iAs), a drinking water and food contaminant, is one of the most widespread environmental diabetogens according to epidemiological studies. Several schemes have been proposed to explain the diabetogenic effects of iAs exposure; however, the exact mechanism remains unknown. We have shown that in vitro exposure to low concentrations of arsenite (iAsIII) or its trivalent methylated metabolites, methylarsonite (MAsIII) and dimethylarsinite (DMAsIII), inhibits glucose-stimulated insulin secretion (GSIS) from isolated pancreatic islets, with little effect on insulin transcription or total insulin content. The goal of this study was to determine if exposure to trivalent arsenicals impairs mitochondrial metabolism, which plays a key role in the regulation of GSIS in β cells. We used a Seahorse extracellular flux analyzer to measure oxygen consumption rate (OCR), a proxy for mitochondrial metabolism, in cultured INS-1 832/13 β cells exposed to iAsIII, MAsIII, or DMAsIII and stimulated with either glucose or pyruvate, a final product of glycolysis and a substrate for the Krebs cycle. We found that 24-h exposure to 2 μM iAsIII or 0.375-0.5 μM MAsIII inhibited OCR in both glucose- and pyruvate-stimulated β cells in a manner that closely paralleled GSIS inhibition. In contrast, 24-h exposure to DMAsIII (up to 2 µM) had no effects on either OCR or GSIS. These results suggest that iAsIII and MAsIII may impair GSIS in β cells by inhibiting mitochondrial metabolism, and that at least one target of these arsenicals is pyruvate decarboxylation or downstream reactions.

The relation between rice consumption, arsenic contamination, and prevalence of diabetes in South Asia

Rice is the major staple food for about two billion people living in Asia. It has been reported to contain considerable amount of inorganic arsenic which is toxic to pancreatic beta cells and disrupt glucose homeostasis. Articles and conference papers published between 1992 and 2017, indexed in Scopus, PubMed, EMBASE, Google, and Google scholar were used. Arsenic exposure has been associated with increased blood glucose and insulin levels, or decreased sensitization of insulin cells to glucose uptake. Several studies have shown the association between inorganic arsenic exposure and incidence of diabetes mellitus. Considerable amounts of arsenic have been reported in different types of rice which may be affected by cultivation methods, processing, and country of production. Use of certain microbes, fertilizers, and enzymes may reduce arsenic uptake or accumulation in rice, which may reduce its risk of toxicity. Combined exposure to contaminated rice, other foods and drinking water may increase the risk of diabetes in these countries. Maximum tolerated daily intake of arsenic contaminated rice (2.1 µg/day kg body weight) has been set by WHO, which may be exceeded depending on its content in rice and amount consumed. Hence, increased prevalence of diabetes in South Asia may be related to the consumption of arsenic contaminated rice depending on its content in the rice and daily amount consumed. In this review, we have focused on the possible relation between rice consumption, arsenic contamination, and prevalence of diabetes in South Asia.

Genetic and epigenetic mechanisms underlying arsenic-associated diabetes mellitus: a perspective of the current evidence

Chronic exposure to arsenic has been associated with the development of diabetes mellitus (DM), a disease characterized by hyperglycemia resulting from dysregulation of glucose homeostasis. This review summarizes four major mechanisms by which arsenic induces diabetes, namely inhibition of insulin-dependent glucose uptake, pancreatic β-cell damage, pancreatic β-cell dysfunction and stimulation of liver gluconeogenesis that are supported by both in vivo and in vitro studies. Additionally, the role of polymorphic variants associated with arsenic toxicity and disease susceptibility, as well as epigenetic modifications associated with arsenic exposure, are considered in the context of arsenic-associated DM. Taken together, in vitro, in vivo and human genetic/epigenetic studies support that arsenic has the potential to induce DM phenotypes and impair key pathways involved in the regulation of glucose homeostasis.

Metabolism disrupting chemicals and metabolic disorders

The recent epidemics of metabolic diseases, obesity, type 2 diabetes(T2D), liver lipid disorders and metabolic syndrome have largely been attributed to genetic background and changes in diet, exercise and aging. However, there is now considerable evidence that other environmental factors may contribute to the rapid increase in the incidence of these metabolic diseases. This review will examine changes to the incidence of obesity, T2D and non-alcoholic fatty liver disease (NAFLD), the contribution of genetics to these disorders and describe the role of the endocrine system in these metabolic disorders. It will then specifically focus on the role of endocrine disrupting chemicals (EDCs) in the etiology of obesity, T2D and NAFLD while finally integrating the information on EDCs on multiple metabolic disorders that could lead to metabolic syndrome. We will specifically examine evidence linking EDC exposures during critical periods of development with metabolic diseases that manifest later in life and across generations.

Arsenic exposure is associated with diminished insulin sensitivity in non-diabetic Amish adults

BACKGROUND

Substantial evidence supports an association between diabetes and arsenic at high exposure levels, but results are mixed at low exposure levels. The aetiology of diabetes involves insulin resistance and β-cell dysfunction. However, only a few epidemiologic studies have examined measures of insulin resistance and β-cell function in relation to arsenic exposure, and no studies have tested for associations with the oral glucose tolerance test (OGTT). We examined the association between urinary total arsenic and OGTT-based markers of insulin sensitivity and β-cell function.

METHODS

We studied 221 non-diabetic adults (mean age = 52.5 years) from the Amish Family Diabetes Study. We computed OGTT-based validated measures of insulin sensitivity and β-cell function. Generalized estimating equations accounting for sibship were used to estimate associations.

RESULTS

After adjusting for age, sex, waist-to-hip ratio and urinary creatinine, an interquartile range increase in urinary total arsenic (6.24 µg/L) was significantly, inversely associated with two insulin sensitivity measures (Stumvoll metabolic clearance rate = -0.23 mg/(kg min), (95% CI: -0.38, -0.089), p = 0.0015; Stumvoll insulin sensitivity index = -0.0029 µmol/(kg min pM), (95% CI: -0.0047, -0.0011), p = 0.0015). Urinary total arsenic was also significantly associated with higher fasting glucose levels (0.57 mg/dL (95% CI: 0.06, 1.09) per interquartile range increase, p = 0.029). No significant associations were found between urinary total arsenic and β-cell function measures.

CONCLUSIONS

This preliminary study found that urinary total arsenic was associated with insulin sensitivity but not β-cell function measures, suggesting that low-level arsenic exposure may influence diabetes risk through impairing insulin sensitivity. Copyright © 2015 John Wiley & Sons, Ltd.

Arsenic and human health effects: A review

Arsenic (As) is ubiquitous in nature and humans being exposed to arsenic via atmospheric air, ground water and food sources are certain. Major sources of arsenic contamination could be either through geological or via anthropogenic activities. In physiological individuals, organ system is described as group of organs that transact collectively and associate with other systems for conventional body functions. Arsenic has been associated with persuading a variety of complications in body organ systems: integumentary, nervous, respiratory, cardiovascular, hematopoietic, immune, endocrine, hepatic, renal, reproductive system and development. In this review, we outline the effects of arsenic on the human body with a main focus on assorted organ systems with respective disease conditions. Additionally, underlying mechanisms of disease development in each organ system due to arsenic have also been explored. Strikingly, arsenic has been able to induce epigenetic changes (in utero) and genetic mutations (a leading cause of cancer) in the body. Occurrence of various arsenic induced health effects involving emerging areas such as epigenetics and cancer along with their respective mechanisms are also briefly discussed.

Low-level sodium arsenite induces apoptosis through inhibiting TrxR activity in pancreatic β-cells

In our previous study, we reported that sodium arsenite induced ROS-dependent apoptosis through lysosomal-mitochondrial pathway in pancreatic β-cells. Since the thioredoxin (Trx) system is the key antioxidant factor in mammalian cells, we investigate whether the inhibition of Trx system contributes to sodium arsenite-induced apoptosis in this study. After treatment with low-level (0.25-1μM) sodium arsenite for 96h, the thioredoxin reductase (TrxR) activity was decreased significantly in pancreatic INS-1 cells. Following with the inactivation of TrxR, ASK1 was released from combining with Trx, which was evidenced by increased levels of ASK1 in sodium arsenite-treated INS-1 cells. Subsequently, activated ASK1 accelerated the expression of proapoptotic protein Bax and reduced the expression of anti-apoptic protein Bcl-2. Finally, low-level sodium arsenite induced apoptosis via caspase-3 in INS-1 cells. Knockdown of ASK1 alleviated sodium arsenite-induced apoptosis. In summary, the precise molecular mechanisms through which arsenic is related to diabetes have not been completely elucidated, inactivation of Trx system might provide insights into the underlying mechanisms at the environmental exposure levels.

Arsenic induces diabetic effects through beta-cell dysfunction and increased gluconeogenesis in mice

Arsenic as a potential risk factor for type 2 diabetes has been received attention recently. However, the roles of arsenic on development of diabetes are unclear. In this study, we compared the influences of inorganic arsenic (iAs) on normal and diabetic mice by systems toxicology approaches. Although iAs exposure did not change glucose tolerance in normal mice, it caused the pancreatic β-cell dysfunction and increased gluconeogenesis and oxidative damages in liver. However, iAs exposure worsened the glucose tolerance in diabetic mice, which might be due to increased gluconeogenesis and impairment of pancreatic β-cell function. It is interesting that iAs exposure could improve the insulin sensitivity based on the insulin tolerance testing by the activation of glucose uptake-related genes and enzymes in normal and diabetic individuals. Our data suggested that iAs exposure could cause pre-diabetic effects by altering the lipid metabolism, gluconeogenesis and insulin secretion in normal individual, and worsen diabetic effects in diabetes individual by these processes. Insulin resistance might be not the reason of diabetic effects caused by iAs, indicating that mechanism of the diabetogenic effects of iAs exposure is different from the mechanism associated with traditional risk factors (such as obesity)-reduced type 2 diabetes.

Association of calpain-10 rs2975760 polymorphism with type 2 diabetes mellitus: a meta-analysis

Type 2 diabetes mellitus (T2DM) accounts for the majority of diabetes cases and affects a significant proportion of the adult population worldwide. Calpain-10 has been implicated in the development of type 2 diabetes, and some polymorphisms in the CAPN10 gene have been associated with an increased risk of developing this disease. Several molecular epidemiological studies were conducted in recent years to evaluate the association between the CAPN10 rs2975760 polymorphism and T2DM risk in diverse populations. However, the results remain conflicting rather than conclusive. We performed a meta-analysis of 8 case-control studies that included 2758 T2DM cases and 2762 case-free controls. We assessed the strength of the association, using odds ratios (ORs) with 95% confi dence intervals (CIs). Overall, this meta-analysis showed that the CAPN10 rs2975760 polymorphism was not associated with a significantly type 2 diabetes risk in three genetic models. However, after excluding two study for its heterogeneity, a significantly increased risk was found in all comparisons (for C vs T: OR=1.14, 95% CI=1.03-1.27, I (2)=0, P heterpgeneity=0.420, P b=0.012; for TC vs TT: OR=1.15, 95% CI=1.01-1.30, I (2)=3.8%, P heterpgeneity=0.392, P b=0.030; for CC+TC vs TT: OR=1.16, 95% CI=1.03-1.31, I (2)=3.7%, P heterpgeneity=0.393, P b=0.015). No publication bias was found in the present study. This meta-analysis suggests that the C allele of the CAPN10 rs2975760 polymorphism is associated with an increased T2DM risk. Further large and well-designed studies are needed to confi rm this association.

Blood biochemistry, thyroid hormones, and oxidant/antioxidant status of guinea pigs challenged with sodium arsenite or arsenic trioxide

The present experiment aimed to compare the two most commonly used compounds of arsenic (sodium arsenite and arsenic trioxide) for their effect on blood metabolites, thyroid hormones, and oxidant/antioxidant status in guinea pigs. Twenty-one adult guinea pigs were randomly divided into three equal groups. Animals in group T1 (control) were fed a basal diet, whereas 50 ppm arsenic was added in the basal diet either as sodium arsenite (T2) or arsenic trioxide (T3) and fed for 11 weeks. Serum aspartate aminotransferase and alanine aminotransferase activities were significantly increased along with a decrease in blood hemoglobin level in both the arsenic-administered groups. The level of erythrocytic antioxidants (catalase, superoxide dismutase, reduced glutathione, glutathione-S-transferase, and glutathione reductase) was decreased and lipid peroxidation was elevated upon arsenic exposure. Serum thyroid hormone levels were reduced and arsenic levels in tissues increased in both the arsenic-exposed groups, irrespective of the arsenic compound. Thus, sodium arsenite and arsenic trioxide exerted similar adverse effects on blood metabolic profile, antioxidant status, and thyroid hormones in guinea pigs.

Sodium arsenite induces ROS-dependent autophagic cell death in pancreatic β-cells

Inorganic arsenic is a worldwide environmental pollutant. Inorganic arsenic's positive relationship with the incidence of type 2 diabetes mellitus arouses concerns associated with its etiology in diabetes among the general human population. In this study, the inhibitor of autophagosome formation, 3-methyladenine, protected the cells against sodium arsenite cytotoxicity, and the autophagy stimulator rapamycin further decreased the cell viability of sodium arsenite-treated INS-1 cells. These finding suggested the hypothesis that autophagic cell death contributed to sodium arsenite-induced cytotoxicity in INS-1 cells. Sodium arsenite increased the autophagosome-positive puncta in INS-1 cells observed under a fluorescence microscope, and this effect was confirmed by the elevated LC3-II levels detected through Western blot. The LC3 turnover assay indicated that the accumulation of autophagosomes in the arsenite-treated INS-1 cells was due to increased formation rather than impaired degradation. The pretreatment of INS-1 cells with the ROS inhibitor NAC reduced autophagosome formation and reversed the sodium arsenite cytotoxicity, indicating that sodium arsenite-induced autophagic cell death was ROS-dependent. In summary, the precise molecular mechanisms through which arsenic is related to diabetes have not been completely elucidated, but the ROS-dependent autophagic cell death of pancreatic β-cells described in this study may help to elucidate the underlying mechanism.

Investigation of Calpain 10 (rs2975760) gene polymorphism in Asian Indians with Gestational Diabetes Mellitus

Background

Type 2 Diabetes Mellitus (T2DM) and Gestational Diabetes Mellitus (GDM) are part of a heterogeneous and complex metabolic group of disorders that share common pathophysiological circumstances, including β-cell dysfunction and insulin resistance. The protein Calpain 10 (CAPN10) plays a role in glucose metabolism, pancreatic β-cell insulin secretion, and thermogenesis.

Objective

Polymerase Chain Reaction–Restriction Fragment Length Polymorphism (PCR–RFLP) based genotyping of CAPN10 (rs2975760) polymorphism was carried out in T2DM and GDM with suitable controls for each of the pathologies from the same population. Genomic DNA was isolated from 787 participants, including 250 cases of T2DM, 287 pregnant women, of which 137 were identified as having GDM and the remaining 150 were confirmed as non-GDM, and 250 healthy control volunteers, and association analysis was carried out for genotypes and alleles.

Results

In the present study, T2DM was compared with healthy controls and was not found to be associated with the CAPN10 C allele (odds ratio, OR: 1.09; 95% CI = 0.8011–1.484; p = 0.5821). GDM also did not show any association when compared with non-GDM (OR: 1.124; 95% CI = 0.7585–1.667; p = 0.5606) respectively.

Conclusion

Our study suggests that the CAPN10 (rs2975760) polymorphism scrutinized in this study is not associated with T2DM and GDM.

•

In this study Calpain 10 (CAPN10) gene was carried out with Type 2 Diabetes Mellitus (T2DM) and Gestational Diabetes Mellitus (GDM). T2DM and GDM are different etiologies of the same complex diseases, frequently coexisting disorders and major components of metabolic syndrome that cause a substantial public health and economic burden worldwide.

•

In this study T2DM, GDM are subsequently studied with rs2975760 polymorphism in CAPN10 gene.

•

Molecular Analysis were performed by PCR-RFLP analysis.

•

A total of 787 samples were included.

Role of calpain-10 in the development of diabetes mellitus and its complications

Calpain activity has been implicated in several cellular processes such as cell signaling, apoptosis, exocytosis, mitochondrial metabolism and cytoskeletal remodeling. Evidence has indicated that the impairment of calpain expression and the activity of different calpain family members are involved in diverse pathologies. Calpain-10 has been implicated in the development of type 2 diabetes, and polymorphisms in the CAPN10 gene have been associated with an increased risk of developing this disease. The present work focused on the molecular biology of calpain-10, supporting its key participation in glucose metabolism. Current knowledge regarding the role of calpain-10 in the development of type 2 diabetes mellitus and diabetes-related diseases is additionally reviewed.