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Pheiffer C.,Biomedical Research and Innovation Platform | Erasmus R.T.,Stellenbosch University | Erasmus R.T.,Non Communicable Diseases Research Unit | Kengne A.P.,Non Communicable Diseases Research Unit | And 2 more authors.
Clinical Biochemistry | Year: 2015

Objective: Accumulating evidence supports the role of epigenetic modifications, and in particular DNA methylation and non-coding RNAs in the pathophysiology of type 2 diabetes. Alterations in methylation patterns within promoter regions are linked with aberrant transcription and pathological gene expression; however the role of methylation within non-promoter regions is not yet fully elucidated. Design and methods: We performed whole genome methylated DNA immunoprecipitation sequencing (MeDIP-Seq) in peripheral-blood-derived DNA from age-gender-body mass index (BMI)-ethnicity matched type 2 diabetic, pre-diabetic and non-diabetic individuals. Results: The density of methylation normalized to the average length of the promoter, intergenic and intragenic regions and to CpG count was 3.17, 9.80 and 0.09 for the promoter, intergenic and intragenic regions, respectively. Methylation within these regions varied according to glucose tolerance status and was associated with hypermethylation rather than hypomethylation. MicroRNA-DNA methylation peaks accounted for 4.8% of the total number of peaks detected. Differential DNA methylation of these microRNA peaks was observed during dysglycemia, with the promoter, intergenic and intragenic regions accounting for 2%, 95% and 3% respectively, of the differentially methylated microRNA peaks. Conclusion: Genome-wide DNA methylation varied according to glucose tolerance. Methylation within non-promoter regions accounted for the majority of differentially methylated peaks identified, thus highlighting the importance of DNA methylation within these non-promoter regions in the pathogenesis of type 2 diabetes. This study suggests that DNA methylation within intergenic regions is a mechanism regulating microRNAs, another increasingly important epigenetic factor, during type 2 diabetes. © 2015 The Canadian Society of Clinical Chemists.


Riedel S.,Biomedical Research and Innovation Platform | Abel S.,Mycotoxicology and Chemoprevention Research Group | Burger H.-M.,Mycotoxicology and Chemoprevention Research Group | van der Westhuizen L.,Cape Peninsula University of Technology | And 3 more authors.
Prostaglandins Leukotrienes and Essential Fatty Acids | Year: 2016

Differential sensitivity of primary hepatocytes and Chang cells to the cancer promoter fumonisin B1 (FB1)-induced cytotoxic effects were investigated in relation to changes in membrane lipid distribution. In contrast to primary hepatocytes, Chang cells were resistant to FB1-induced cytotoxic effects. This was associated with a high cholesterol (Chol) and sphingomyelin (SM) and low phosphatidylcholine (PC) content, resulting in a significant (P<0.05) decrease in phosphatidylethanolamine (PE)/PC ratio, increased Chol/total phosphoglyceride (TPG) ratios and low total polyunsaturated fatty acids (PUFA) content in PC and PE, suggesting a more rigid membrane structure. High levels of C18:1 and reduced polyunsaturated fatty acid (PUFA) levels are likely to provide selective resistance to FB1-induced oxidative stress. FB1-associated lipid changes included decreases in SM and Chol, increases in sphinganine (Sa) and PE with the increases in key saturated, monounsaturated, and PUFAs in PE as key role players in the differential responses to FB1-induced cell growth responses in cells. © 2016 Elsevier Ltd.


Johnson R.,Biomedical Research and Innovation Platform | Dludla P.,Biomedical Research and Innovation Platform | Dludla P.,Stellenbosch University | Joubert E.,ARC Technology | And 6 more authors.
Molecular Nutrition and Food Research | Year: 2016

Scope: Energy deprivation in the myocardium is associated with impaired heart function. This study aims to investigate if aspalathin (ASP) can ameliorate hyperglycemic-induced shift in substrate preference and protect the myocardium against cell apoptosis. Methods and results: H9c2 cells were exposed to, either normal (5.5 mM) or high (33 mM) glucose concentrations for 48 h. Thereafter, cells exposed to 33 mM glucose were treated with metformin (1 μM) or ASP (1 μM), as well as a combination of metformin and ASP for 6 h. In vitro studies revealed that ASP improved glucose metabolism by decreasing fatty acid uptake and subsequent β-oxidation through the decreased expression of adenosine monophosphate-activated protein kinase threonine 172 (pAMPK (Thr172)) and carnitine palmitoyltransferase 1 (CPT1), while increasing acetyl-CoA carboxylase (ACC) and glucose transporter 4 (GLUT4) expression. ASP inhibited high glucose induced loss of membrane potential in H9c2 cells as observed by an increase in 5′ 6,6′-tetrachloro-1,1′,3,3′ -tetraethylbenzimidazolyl-carbocyanine iodide (JC-1) ratio (orange\red fluorescence) and decreased apoptosis by reducing intracellular reactive oxygen species and DNA nick formation, while increasing glutathione, superoxide dismutase, uncoupling protein 2 (UCP2), and Bcl-2\Bax ratio. Conclusion: Our study provides evidence that ASP increases glucose oxidation and modulates fatty acid utilization producing a favorable substrate shift in H9c2 cardiomyocytes exposed to high glucose. Such a favorable shift will be of importance in the protection of cardiomyocytes in the diabetic heart. Aspalathin protects H9c2 cardiomyocytes against high glucose induced shifts in substrate preference and apoptosis by activating AMPK. AMPK, 5′ AMP-activated protein kinase; ATP, adenosine triphosphate; CD36, cluster of differentiation 36; CPT1, carnitine palmitoyltransferase I; FAU, fatty acid uptake; G-6-P, glucose-6-phosphate; GLUT4, glucose transporter 4; GSH, glutathione; GU, glucose uptake; MPC, mitochondrial pyruvate carrier; PDH, pyruvate dehydrogenase; ROS, reactive oxygen species; SOD, superoxide dismutase activity; TCA, tricarboxylic acid; UCP2, uncoupling protein 2. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.


Pheiffer C.,Biomedical Research and Innovation Platform | Jacobs C.,Biomedical Research and Innovation Platform | Patel O.,Biomedical Research and Innovation Platform | Ghoor S.,Biomedical Research and Innovation Platform | And 2 more authors.
Journal of Physiology and Biochemistry | Year: 2016

Obesity, a complex metabolic disorder, is characterized by mitochondrial dysfunction and oxidative stress. Increased expression of uncoupling protein 2 (UCP2) during obesity is an adaptive response to suppress the production of reactive oxygen species. The aims of this study were to compare the expression of UCP2 in diet-induced obese Wistar rats that differed according to age and their severity of obesity, and to compare UCP2 expression in the liver and muscle of these rats. UCP2 messenger RNA and protein expression was increased 4.6-fold (p < 0.0001) and 3.0-fold (p < 0.05), respectively, in the liver of the older and heavier rats. In contrast, UCP2 expression was decreased twofold (p < 0.005) in the muscle of these rats, while UCP3 messenger RNA (mRNA) was increased twofold (p < 0.01). Peroxisome proliferator-activated receptor alpha (PPARα) was similarly increased (3.0-fold, p < 0.05) in the liver of the older and more severe obese rats. Total protein content was increased (2.3-fold, p < 0.0001), while 5′ adenosine monophosphate-activated protein kinase (AMPK) activity was decreased (1.3-fold, p = 0.05) in the liver of the older, heavier rats. No difference in total protein content and AMPK expression was observed in the muscle of these rats. This study showed that the expression of UCP2 varies according to age and the severity of obesity and supports the widely held notion that increased UCP2 expression is an adaptive response to increased fatty acid β-oxidation and reactive oxygen species production that occurs during obesity. An understanding of metabolic adaptation is imperative to gain insight into the underlying causes of disease, thus facilitating intervention strategies to combat disease progression. © 2015, University of Navarra.

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