IRS-1 gene polymorphism and DNA damage in pregnant women with diabetes or mild gestational hyperglycemia

The association between gestational diabetes mellitus and DNA damage in umbilical cord leukocytes and placental samples

Objective(s): To evaluate the relation between gestational diabetes mellitus (GDM) and maternal and/or fetal DNA integrity. Method: 59 pregnant women were classified into two groups on the basis of 75 g oral glucose tolerance test (OGTT) and glycemic profile (GP): Control group (OGTT and GP normal, n = 29) and GDM group (abnormal 75 g OGTT, n = 30). The umbilical cord blood and placental samples obtained from the maternal side were collected at the time of delivery. Alkaline comet assay was performed for the determination of DNA damage. The trial was approved with the protocol number 72867572.050.01.04-299082. Result(s): Body mass index (BMI), weight gain during pregnancy, glycemic means and fetal weight were increased in GDM group compared control group (p = .01, .0001, .04, and .01, respectively). In the GDM group, the number of large-for-gestational-age (LGA) infants was significantly higher compared to the nondiabetic group (p = .04). Tail DNA percentages in placental samples were higher in the GDM group compared to controls (p = .01); however, DNA integrity in umbilical cord leukocytes was similar between the groups (p = 0.1). In contrast to umbilical cord DNA damage, placental DNA damage showed positive correlation with maternal glycemia in the whole group and within each group. The positive association of placental DNA damage and GDM remained after adjusting for age, BMI, smoking, glycemia, gestational age at delivery, fetal weight at delivery, and delivery type (p = .01). Conclusion(s): Placental DNA damage is associated with GDM and placental cells seem to be more vulnerable to DNA damage compared to fetal blood cells.

GST T1, M1, and IRS-1 G972R Genetic Variants Association to Gestational Diabetes Mellitus (GDM) in Egyptian Women: Linkage to Maternal Hyperglycemia

BACKGROUND

Gestational Diabetes Mellitus (GDM) shares in part the pathogenic mechanisms of multiple genetic interactions. Some of the T2D susceptibility genes are encountered in association with GDM.

OBJECTIVE

We aimed to investigate GST T1, M1, and G972R IRS-I gene polymorphisms with the risk of developing GDM.

METHODS

In this randomized case-control study, pregnant women with GDM were genotyped by PCR analysis for glutathione s-transferase-T1, M1 variant polymorphisms. RFLP was done for the G972R IRS 1 gene. Their newborns were additionally assayed for the whole of the clinical, laboratory, and genetic aspects.

RESULTS

The T allele IRS-1rs1801278 TT genotype was more frequently detected in GDM mothers in comparison to healthy control ones [for TT homozygous variant; OR(CI 95%): 2.05(1.09-3.87, p: 0.025)]. Furthermore, GST T1 null was significantly presented in GDM mothers than those of control mothers [OR (CI95%: 0.29 (0.084-1.02), p:0.04]. Added to the significant correlation of glycemic indices to clinical parameters of infants born to GDM, the M1-null genotype of GST was significantly correlated (p<0.05) to abnormal values of respiratory rates and 1 minute-APGAR score noted for extra NICU care.

CONCLUSION

Our results suggested that GST T1null and IRS-1 TT genotypic variants were claimed for GDM development among Egyptian women with a possible impact on their newly born infants.

Diabetes, Oxidative Stress, and DNA Damage Modulate Cranial Neural Crest Cell Development and the Phenotype Variability of Craniofacial Disorders

Craniofacial malformations are among the most common birth defects in humans and they often have significant detrimental functional, aesthetic, and social consequences. To date, more than 700 distinct craniofacial disorders have been described. However, the genetic, environmental, and developmental origins of most of these conditions remain to be determined. This gap in our knowledge is hampered in part by the tremendous phenotypic diversity evident in craniofacial syndromes but is also due to our limited understanding of the signals and mechanisms governing normal craniofacial development and variation. The principles of Mendelian inheritance have uncovered the etiology of relatively few complex craniofacial traits and consequently, the variability of craniofacial syndromes and phenotypes both within families and between families is often attributed to variable gene expression and incomplete penetrance. However, it is becoming increasingly apparent that phenotypic variation is often the result of combinatorial genetic and non-genetic factors. Major non-genetic factors include environmental effectors such as pregestational maternal diabetes, which is well-known to increase the risk of craniofacial birth defects. The hyperglycemia characteristic of diabetes causes oxidative stress which in turn can result in genotoxic stress, DNA damage, metabolic alterations, and subsequently perturbed embryogenesis. In this review we explore the importance of gene-environment associations involving diabetes, oxidative stress, and DNA damage during cranial neural crest cell development, which may underpin the phenotypic variability observed in specific craniofacial syndromes.

Association of IRS1 Gly972Arg and IRS2 Gly1057Asp polymorphisms with gastric cancer in Turkish subjects

Insulin receptor substrate (IRS) proteins are cytoplasmic adaptors that transmit the signal from the IR and insulin-like growth factor-1 receptor to effector proteins. Overexpression of IRS proteins has been indicated to be linked to cancer development. In addition to their expression profiles, studies have indicated that polymorphisms of IRS1 and IRS2 are also associated with the susceptibility to numerous cancer types. IRS1 Gly972Arg and IRS2 Gly1057Asp are the common variants of these genes. The present study aimed to determine the association of IRS1 Gly972Arg and IRS2 Gly1057Asp polymorphisms with gastric cancer development. The study included 100 patients with gastric cancer and 100 controls. Single-nucleotide polymorphisms were detected by real-time PCR using Taqman assays. The results suggested that in individuals with the IRS1 Gly/Arg genotype, the odds of having gastric cancer was increased by 7.891-fold (95% CI: 3.251-19.154, P<0.001) and in individuals with the IRS1 Arg/Arg genotype, it was increased by 22.716-fold (95% CI: 6.311-81.761, P<0.001) compared with those with the IRS1 Gly/Gly genotype. Although the IRS2 Gly1057Asp genotype analysis suggested that subjects with the Asp/Asp genotype had a 2,311-fold increased odds of having gastric cancer compared to those with the Gly/Gly genotype, the result was not statistically significant (95% CI: 0.800-6.678, P=0.122). The combined effects of the IRS1 and IRS2 variants on gastric cancer were also determined. The results suggested that individuals with Gly/Arg+Gly/Asp and Gly/Arg+Asp/Asp genotypes had a higher odds of having gastric cancer compared to individuals of the Gly/Gly+Gly/Gly genotype (P=0.001 and P=0.027, respectively). In conclusion, the present results suggested that the IRS1 Gly972Arg and IRS2 Gly1057Asp variations may be associated with an increased susceptibility to develop gastric cancer. Further studies with larger sample sizes are required to support the present results and to explore the use of these variations as a biomarker for gastric cancer.

A diterpene derivative enhanced insulin signaling induced by high glucose level in HepG2 cells

The predominant feature of type 2 diabetes is insulin resistance. Identifying a drug able to reduce insulin resistance is an urgent requirement. ent-3α-Formylabieta-8(14),13(15)-dien-16,12β-olide had been identified as a new diterpene derivative which showed anticancer activity. This study explores the hypoglycemic effect of ent-3α-formylabieta-8(14),13(15)-dien-16,12β-olide and studied its mechanism. The insulin response of HepG2 cells following ent-3α-formylabieta-8(14),13(15)-dien-16,12β-olide treatment, as a model for liver cancer cells, was assessed. The results demonstrated that hyperglycemia resulted in a significant increase in the levels of insulin receptor substrate-1 (IRS-1) serine phosphorylation and decrease in Akt phosphorylation. High glucose also inhibited the phosphorylation of insulin-dependent GSK3β. ent-3α-Formylabieta-8(14),13(15)-dien-16,12β-olide treatment improved the effect of insulin on the phosphorylation of IRS-1 Ser307. In addition, this study demonstrated that the effect of ent-3α-formylabieta-8(14),13(15)-dien-16,12β-olide was dependent on the activation of AMP-activated protein kinase. Collectively, experimental data indicated an association between insulin resistance and hyperglycemia in HepG2 cells, and that ent-3α-formylabieta-8(14),13(15)-dien-16,12β-olide reduces IRS-1 Ser307 phosphorylation via activating AMPK, thereby decreasing the insulin signaling blockade.

Altered maternal metabolism during mild gestational hyperglycemia as a predictor of adverse perinatal outcomes: A comprehensive analysis

Mild gestational hyperglycemia (MGH), as assessed using the normal oral glucose tolerance test (OGTT) and detection of an altered glycemic profile, is associated with adverse perinatal outcome. This study described the results of 40 years of research conducted at the Perinatal Diabetes Research Centre at São Paulo State University (UNESP), Brazil, on the maternal MGH environment and placental markers. This study also described the unidirectional relationship between MGH and excessive fetal growth, also supplying moderator analysis. In addition to hyperglycemia, MGH is associated with an increased incidence of hypertension, metabolic syndrome, persistent insulin resistance after pregnancy, and high risk of developing type 2 diabetes mellitus (T2DM) after pregnancy. Structural changes and functional abnormalities resulting from MGH were observed in placenta. The fully adjusted model concluded that the predictor variable (MGH), which creates a complex environment for the fetus, has a direct effect on excessive birth weight and produces a z-score for ratios of birth weight to gestational age of ≥2. Maternal age, pre-pregnancy BMI, number of previous pregnancies, numbers of prenatal visits, and 1 h OGTT are moderator variables that impact MGH and excessive fetal growth. These results show that maternal MGH has some characteristics associated with similar long-term T2DM development and similar adverse perinatal results to those of gestational diabetes mellitus (GDM) mothers, making it an intermediate maternal and placental marker between normoglycemic and GDM mothers.

An integrative review of associations between polymorphic variants and the metabolic syndrome

The pathogenesis of metabolic syndrome, i.e. of each of its components, is complex and has not been entirely elucidated. As a result, it is very difficult to establish a definition of which clinical factors are the most important determinants of its development. The objective of this review is to describe Brazilian scientific research investigating associations between the metabolic syndrome and genetic factors. We selected fifteen studies that met the inclusion and exclusion criteria. Our analysis revealed that there is a modest volume of Brazilian studies investigating relationships between genes, their polymorphic variants and the metabolic syndrome and its risk factors. Therefore, more studies are needed to better understand the biological roles played by genetic polymorphisms and their relationships with metabolic syndrome or its risk factors.

From Sea to Shining Sea and the Great Plains to Patagonia: A Review on Current Knowledge of Diabetes Mellitus in Hispanics/Latinos in the US and Latin America

The past two decades have witnessed many advances in the prevention, treatment, and control of diabetes mellitus (DM) and its complications. Increased screening has led to a greater recognition of type 2 diabetes mellitus (type 2 DM) and prediabetes; however, Hispanics/Latinos, the largest minority group in the US, have not fully benefited from these advances. The Hispanic/Latino population is highly diverse in ancestries, birth places, cultures, languages, and socioeconomic backgrounds, and it populates most of the Western Hemisphere. In the US, the prevalence of DM varies among Hispanic/Latino heritage groups, being higher among Mexicans, Puerto Ricans, and Dominicans, and lower among South Americans. The risk and prevalence of diabetes among Hispanics/Latinos are significantly higher than in non-Hispanic Whites, and nearly 40% of Hispanics/Latinos with diabetes have not been formally diagnosed. Despite these striking facts, the representation of Hispanics/Latinos in pharmacological and non-pharmacological clinical trials has been suboptimal, while the prevalence of diabetes in these populations continues to rise. This review will focus on the epidemiology, etiology and prevention of type 2 DM in populations of Latin American origin. We will set the stage by defining the terms Hispanic, Latino, and Latin American, explaining the challenges identifying Hispanics/Latinos in the scientific literature and databases, describing the epidemiology of diabetes-including type 2 DM and gestational diabetes mellitus (GDM)-and cardiovascular risk factors in Hispanics/Latinos in the US and Latin America, and discussing trends, and commonalities and differences across studies and populations, including methodology to ascertain diabetes. We will discuss studies on mechanisms of disease, and research on prevention of type 2 DM in Hispanics/Latinos, including women with GDM, youth and adults; and finalize with a discussion on lessons learned and opportunities to enhance research, and, consequently, clinical care oriented toward preventing type 2 DM in Hispanics/Latinos in the US and Latin America.

Targeting Mitochondria and Reactive Oxygen Species-Driven Pathogenesis in Diabetic Nephropathy

Diabetic kidney disease is one of the major microvascular complications of both type 1 and type 2 diabetes mellitus. Approximately 30% of patients with diabetes experience renal complications. Current clinical therapies can only mitigate the symptoms and delay the progression to end-stage renal disease, but not prevent or reverse it. Oxidative stress is an important player in the pathogenesis of diabetic nephropathy. The activity of reactive oxygen and nitrogen species (ROS/NS), which are by-products of the diabetic milieu, has been found to correlate with pathological changes observed in the diabetic kidney. However, many clinical studies have failed to establish that antioxidant therapy is renoprotective. The discovery that increased ROS/NS activity is linked to mitochondrial dysfunction, endoplasmic reticulum stress, inflammation, cellular senescence, and cell death calls for a refined approach to antioxidant therapy. It is becoming clear that mitochondria play a key role in the generation of ROS/NS and their consequences on the cellular pathways involved in apoptotic cell death in the diabetic kidney. Oxidative stress has also been associated with necrosis via induction of mitochondrial permeability transition. This review highlights the importance of mitochondria in regulating redox balance, modulating cellular responses to oxidative stress, and influencing cell death pathways in diabetic kidney disease. ROS/NS-mediated cellular dysfunction corresponds with progressive disease in the diabetic kidney, and consequently represents an important clinical target. Based on this consideration, this review also examines current therapeutic interventions to prevent ROS/NS-derived injury in the diabetic kidney. These interventions, mainly aimed at reducing or preventing mitochondrial-generated oxidative stress, improving mitochondrial antioxidant defense, and maintaining mitochondrial integrity, may deliver alternative approaches to halt or prevent diabetic kidney disease.