Hyperthermia-induced Hsp90·eNOS preserves mitochondrial respiration in hyperglycemic endothelial cells by down-regulating Glut-1 and up-regulating G6PD activity

Research progress of hyperthermia in tumor therapy by influencing metabolic reprogramming of tumor cells

Cellular metabolic reprogramming is an important feature of malignant tumors. Metabolic reprogramming causes changes in the levels or types of specific metabolites inside and outside the cell, which affects tumorigenesis and progression by influencing gene expression, the cellular state, and the tumor microenvironment. During tumorigenesis, a series of changes in the glucose metabolism, fatty acid metabolism, amino acid metabolism, and cholesterol metabolism of tumor cells occur, which are involved in the process of cellular carcinogenesis and constitute part of the underlying mechanisms of tumor formation. Hyperthermia, as one of the main therapeutic tools for malignant tumors, has obvious effects on tumor cell metabolism. In this paper, we will combine the latest research progress in the field of cellular metabolic reprogramming and focus on the current experimental research and clinical treatment of hyperthermia in cellular metabolic reprogramming to discuss the feasibility of cellular metabolic reprogramming-related mechanisms guiding hyperthermia in malignant tumor treatment, so as to provide more ideas for hyperthermia to treat malignant tumors through the direction of cellular metabolic reprogramming.

Maternal Common Cold or Fever During Pregnancy and the Risk of Orofacial Clefts in the Offspring: A Systematic Review and Meta-analysis

The common cold and/or an associated fever during pregnancy have/has been suspected to harm the developing fetus. We sought possible correlations between a maternal common cold or fever during pregnancy and the risk of orofacial clefts in the offspring.

We systematically searched PubMed and Embase using appropriate keywords, and we checked the reference lists of retrieved articles. We used random-effects models to estimate overall relative risks.

Incidence of orofacial clefts.

We included 13 case-control studies. Modest but statistically significant associations were found between a maternal common cold and cleft lip with or without a cleft palate (CL/CP) (odds ratio [OR] 2.17; 95% confidence interval [CI] 1.66-2.83) and a cleft palate only (CPO) (OR 3.08; 95% CI 1.5-6.34). Furthermore, maternal fever was also associated with an increased risk of CL/CP (OR 1.91, 95% CI 1.3-2.8) and CPO (OR 1.48, 95% CI 0.83-2.63) in the offspring. Further analyses of maternal influenza (alone) yielded similar results.

Although evidence of heterogeneity should be carefully evaluated, our findings suggest that maternal common cold or fever during pregnancy may be associated with a greater risk of CL/CP or CPO in the offspring. Future cohort studies using valid assessments of maternal common cold exposure during pregnancy that consider the severity of fever are needed to clarify the contribution of maternal common cold or fever status to the risk of orofacial clefts in children.

G6PD, bond by miR-24, regulates mitochondrial dysfunction and oxidative stress in phenylephrine-induced hypertrophic cardiomyocytes

AIMS

Pathological cardiac hypertrophy (CH) is one of the main risk factors for heart failure and cardiac death. Mitochondrial dysfunction and oxidative stress often occur in hypertrophic cardiomyocytes. It was recently proposed that deficiency or decreased activity of glucose-6-phosphate dehydrogenase (G6PD) may be related to the development of CH. This study aimed to investigate the expression of G6PD in CH and its regulatory role in mitochondrial dysfunction and oxidative stress of CH cells.

MAIN METHODS

Phenylephrine (PE) was used to create an in vitro model of CH. Using RT-qPCR and western blotting, the expression levels of target mRNAs and proteins were measured. ELISA assays and commercial kits based on spectrophotometry or colorimetry were used to measure mitochondrial function and oxidative stress. TargetScan and luciferase reporter gene assays were utilized for combination prediction and validation. CCK-8 and TUNEL kit were used to determine cell viability and apoptosis.

KEY FINDINGS

The results showed that G6PD overexpression attenuated the decreases of mitochondrial respiration, ATP, ATP synthetase and mitochondrial membrane potential induced by PE, as well as the increases of LDH release and apoptosis. Besides, PE elevated ROS activity, NO and MDA contents, and reduced SOD, CAT levels and cell viability. These effects were hindered by G6PD overexpression. MiR-24 was found to directly bind to G6PD at the motif of CUGAGCC and regulated its expression, furtherly, influenced the G6PD-mediated mitochondrial dysfunction and oxidative stress of CH cells.

SIGNIFICANCE

Generally, our study demonstrated that miR-24/G6PD regulates mitochondrial dysfunction and oxidative stress in CH cells, representing a new sight for CH therapy.

Heat Shock Proteins in Vascular Diabetic Complications: Review and Future Perspective

Heat shock proteins (HSPs) are a large family of proteins highly conserved throughout evolution because of their unique cytoprotective properties. Besides assisting protein refolding and regulating proteostasis under stressful conditions, HSPs also play an important role in protecting cells from oxidative stress, inflammation, and apoptosis. Therefore, HSPs are crucial in counteracting the deleterious effects of hyperglycemia in target organs of diabetes vascular complications. Changes in HSP expression have been demonstrated in diabetic complications and functionally related to hyperglycemia-induced cell injury. Moreover, associations between diabetic complications and altered circulating levels of both HSPs and anti-HSPs have been shown in clinical studies. HSPs thus represent an exciting therapeutic opportunity and might also be valuable as clinical biomarkers. However, this field of research is still in its infancy and further studies in both experimental diabetes and humans are required to gain a full understanding of HSP relevance. In this review, we summarize current knowledge and discuss future perspective.

25-Hydroxycholesterol impairs endothelial function and vasodilation by uncoupling and inhibiting endothelial nitric oxide synthase

Endothelial dysfunction is a key early step in atherosclerosis. 25-Hydroxycholesterol (25-OHC) is found in atherosclerotic lesions. However, whether 25-OHC promotes atherosclerosis is unclear. Here, we hypothesized that 25-OHC, a proinflammatory lipid, can impair endothelial function, which may play an important role in atherosclerosis. Bovine aortic endothelial cells were incubated with 25-OHC. Endothelial cell proliferation, migration, and tube formation were measured. Nitric oxide (NO) production and superoxide anion generation were determined. The expression and phosphorylation of endothelial NO synthase (eNOS) and Akt as well as the association of eNOS and heat shock protein (HSP)90 were detected by immunoblot analysis and immunoprecipitation. Endothelial cell apoptosis was monitored by TUNEL staining and caspase-3 activity, and expression of Bcl-2, Bax, cleaved caspase-9, and cleaved caspase-3 were detected by immunoblot analysis. Finally, aortic rings from Sprague-Dawley rats were isolated and treated with 25-OHC, and endothelium-dependent vasodilation was evaluated. 25-OHC significantly inhibited endothelial cell proliferation, migration, and tube formation. 25-OHC markedly decreased NO production and increased superoxide anion generation. 25-OHC reduced the phosphorylation of Akt and eNOS and the association of eNOS and HSP90. 25-OHC also enhanced endothelial cell apoptosis by decreasing Bcl-2 expression and increasing cleaved caspase-9 and cleaved caspase-3 expressions as well as caspase-3 activity. 25-OHC impaired endothelium-dependent vasodilation. These data demonstrated that 25-OHC could impair endothelial function by uncoupling and inhibiting eNOS activity as well as by inducing endothelial cell apoptosis. Our findings indicate that 25-OHC may play an important role in regulating atherosclerosis.

Nuclear factor-like factor 2-antioxidant response element signaling activation by tert-butylhydroquinone attenuates acute heat stress in bovine mammary epithelial cells

Nuclear factor (erythroid-derived 2)-like factor 2 (Nrf2) is a transcription factor that binds to the antioxidant response element (ARE) in the upstream promoter region of many antioxidative genes. The Nrf2-ARE signaling plays a key role in the cellular antioxidant-defense system, but whether Nrf2 activation has protective effects against heat shock (HS) stress in mammary epithelial cells (MEC) remains unclear. The objective of this study was to determine whether tert-butylhydroquinone (tBHQ), a well-known Nrf2 activator, could attenuate heat stress-induced cell damage in MAC-T cells of the bovine MEC line. The MAC-T cells were exposed to HS (42.5°C for 1h) followed by recovery at 37°C to mimic HS. Compared with cells that were consistently cultured at normothermia (37°C), the cell viability levels significantly decreased after HS stress. In parallel, heat stress increased the reactive oxygen species levels and induced cellular apoptosis and endoplasmic reticulum stress. The MAC-T cells that were pretreated with tBHQ (10μM) for 2h followed by HS had a reduction in the loss of cell viability. The tBHQ pretreatment significantly decreased cellular reactive oxygen species levels and stress-related marker gene expression. The tBHQ-treated MAC-T cells showed strong Nrf2-ARE signaling activation and a nuclear accumulation of Nrf2 and upregulated expression of Nrf2-ARE downstream genes. Small interfering RNA silencing of Nrf2 in HS-treated MAC-T cells almost completely abolished the cytoprotective effects by tBHQ. Overall, our results demonstrated that HS could cause cell damage in cultured bovine MEC, and that activation of Nrf2 by tBHQ could attenuate HS-induced cell damage.

Changes in glucose transporter expression and nitric oxide production are associated with liver injury in diabetes

In diabetes mellitus (DM), both hyperglycaemia and hyperlipidaemia can initiate accumulation of fat in the liver, which might be further mediated by inducible nitric oxide synthase. We have studied changes in GLUT1, nitric oxide (NO(·)) concentration and liver damage in two rat DM models. STZ model was induced by strepozotocin 50 mg/kg. HS model was induced by high-fat diet and 30 mg/kg streptozotocin. GLUT1 expression was studied by means of real-time RT-PCR and immunohistochemistry. Production of NO(·) was monitored by means of erythrocyte sedimentation rate spectroscopy of Fe-DETC-NO complex. Liver damage was assessed using histological activity index (HAI). NO(·) concentration was increased in the liver of STZ rats, but it did not change in HS rats (control 36.8 ± 10.3; STZ 142.1 ± 31.1; HS 35.4 ± 9.8 ng/g). Liver HAI was higher in STZ group, 8.6 ± 0.17 versus HS 4.7 ± 0.31, p < 0.05. GLUT1 protein expression was elevated only in STZ group, 16 ± 3 cells/mm(2) versus Control 5 ± 2 cells/mm(2), p = 0.007. Hyperglycaemia sooner causes severe liver damage in rat models of DM, compared with hyperlipidaemia, and is associated with increased NO(·) production. GLUT1 transporter expression might be involved in toxic effects of glucose in the liver. We have obtained novel data about association of GLUT1 expression and NO(·) metabolism in the pathogenesis of liver injury in DM. Increased GLUT1 expression was observed together with overproduction of NO(·) and pronounced liver injury in severely hyperglycaemic rats. On the contrary, moderately hyperglycaemic hyperlipidaemic rats developed only moderate liver steatosis and no increase in GLUT1 and NO(·). GLUT1 overexpression might be implicated in the toxic effects of glucose in the liver. Glycotoxicity is associated with oxidative stress and NO(·) hyperproduction. GLUT1 and NO(·) metabolism might become novel therapeutic targets in liver steatosis.

Involvement of insulin-induced reversible chromatin remodeling in altering the expression of oxidative stress-responsive genes under hyperglycemia in 3T3-L1 preadipocytes

The epigenetic control mechanisms, regulating insulin-induced oxidative stress generation, under hyperglycemic condition are yet to be elucidated. We set out to assess the role of chromatin regulatory factors in regulating the transcription of genes that are critical for mediating oxidative stress response under hyperglycemic/hyperinsulinemic condition. Our results outline a significant increase in the ROS generation accompanied by a decrease in the histone H3 acetylation, H3 Ser-10 phosphorylation, H3K4 methylation and an increase in the H3K9 methylation, after 30 min of insulin treatment under hyperglycemic condition. However, after 12h of insulin treatment a reversal of these histone H3 modifications was observed which commensurate with the reduced ROS generation. Microarray data revealed that the expression of stress responsive genes (Hsp90, Hspd1, DnajC15, Hsf5 and Mapk3) decreased after12h of insulin treatment, after an initial increase at 30 min. We observed the direct regulation of these stress responsive genes by reversible histone modifications under hyperglycemic/hyperinsulinemic condition at both time intervals. Further, pre-incubation with catalase attenuates these changes. To the best of our knowledge this is the first report that shows the role of reversible histone modifications in regulating oxidative stress-responsive genes under hyperglycemic condition in 3T3-L1 preadipocytes.

Role of genetic changes in the progression of cardiovascular diseases

This review aims to investigate the role of genetic changes in the development of cardiovascular diseases [CVD]. Oxidation of Low density Lipoprotein (LDL) and mutations in LDL receptors gene are a trigger for numerous of atherogenic events. Also, endothelial nitric oxide synthase (eNOS) plays an important role in vasodilatation of blood vessels through synthesis of nitric oxide. Three single base pair changes, 786T/C, 922A/G, and 1468T/A, have been identified in the promoter region of the eNOS gene and are associated with coronary spasm. Moreover, two distinct variable nucleotide tandem repeats (VNTRs) in introns 4 and 13 have been detected. The presence of a minimum of 38 CA repeats in intron 13 has been associated with an independent 2.2-fold increase in the risk of coronary artery disease [CAD]. Plasma glutathione peroxidase (GPx-3) maintains the vascular bioavailability of nitric oxide (NO), through depletion of reactive oxygen species. Mutation(s) or polymorphism(s) in the plasma GPx-3 gene promoter may predispose to a thrombotic disorder, and constitute a genetic risk factor for thrombotic cerebrovascular disease. Hyperhomocysteinemia is another independent risk factor for atherosclerosis and arterial thrombosis. Severe hyperhomocysteinemia could be caused by cystathionine-β-synthase enzyme deficiency but it could be due to homozygosity of a common 677C/T point mutation in the coding region of the methylenetetrahydrofolate reductase (MTHFR) gene as a 3-fold increase in risk of CAD is associated with the MTHFR 677TT genotype. A second common variant in MTHFR 1298A/C is associated with decreased enzyme activity in vitro and in vivo, especially when occurring simultaneously with the 677 C/T polymorphism. Elevated fibrinogen, an essential component of the coagulation system, has been most consistently associated with arterial thrombotic disorders. Several polymorphisms (148C/T, 455G/A, and -854G/A) have been identified in the genes encoding the 3 pairs of fibrinogen polypeptide chains. The -455G/A, and -854G/A substitutions are the most physiologically relevant mutations. In addition the -455A allele has been associated with the progression of atheroma, and also with a 2.5-fold increase in risk of multiple lacunar infarcts in a cohort of elderly patients with stroke. It is concluded that genetic changes in the previously mentioned genes could play a significant role in the initiation and progression of CVD. This review provides useful information for both physicians and medical students whom are interested in human genetics which is related to cardiovascular diseases.

Signaling of reactive oxygen and nitrogen species in Diabetes mellitus

Disorder of physiological signaling functions of reactive oxygen species (ROS) superoxide and hydrogen peroxide and reactive nitrogen species (RNS) nitric oxide and peroxynitrite is an important feature of diabetes mellitus type 1 and type 2. It is now known that hyperglycemic conditions of cells are associated with the enhanced levels of ROS mainly generated by mitochondria and NADPH oxidase. It has been established that ROS stimulate many enzymatic cascades under normal physiological conditions, but hyperglycemia causes ROS overproduction and the deregulation of ROS signaling pathways initiating the development of diabetes mellitus. On the other hand the deregulation of RNS signaling leads basically to a decrease in NO formation with subsequent damaging disorders. In the present work we will consider the pathological changes of ROS and RNS signaling in enzyme/gene regulated processes catalyzed by protein kinases C and B (Akt/B), phosphatidylinositol 3'-kinase (PI3-kinase), extracellular signal-regulated kinase 1/2 (ERK1/2), and some others. Furthermore we will discuss a particularly important role of several ROS-regulated genes and adapter proteins such as the p66shc, FOXO3a, and Sirt2. The effects of low and high ROS levels in diabetes will be also considered. Thus the regulation of damaging ROS levels in diabetes by antioxidants and free radical scavengers must be one of promising treatment of this disease, however, because of the inability of traditional antioxidative vitamin E and C to interact with superoxide and hydrogen peroxide, new free radical scavengers such as flavonoids, quinones and synthetic mimetics of superoxide dismutase (SOD) should be intensively studied.