Identification of Circular RNA Profiles in the Liver of Diet-Induced Obese Mice and Construction of the ceRNA Network.

Obesity is a major risk factor for cardiovascular, cerebrovascular, metabolic, and respiratory diseases, and it has become an important social health problem affecting the health of the population. Obesity is affected by both genetic and environmental factors. In this study, we constructed a diet-induced obese C57BL/6J mouse model and performed deep RNA sequencing (RNA-seq) on liner-depleted RNA extracted from the liver tissues of the mice to explore the underlying mechanisms of obesity. A total of 7469 circular RNAs (circRNAs) were detected, and 21 were differentially expressed (DE) in the high-fat diet (HFD) and low-fat diet (LFD) groups. We then constructed a comprehensive circRNA-associated competing endogenous RNA (ceRNA) network. Bioinformatic analysis indicated that DE circRNAs associated with lipid metabolic-related pathways may act as miRNA sponges to modulate target gene expression. CircRNA1709 and circRNA4842 may serve as new candidates to regulate the expression of PTEN. This study provides systematic circRNA-associated ceRNA profiling in HFD mouse liver, and the results can aid early diagnosis and the selection of treatment targets for obesity in the future.

Modulation of Perturbed Cardiac Metabolism in Rats Under High-Altitude Hypoxia by Combination Treatment With L-carnitine and Trimetazidine.

High-altitude hypoxia has long been recognized as a vital etiology for high-altitude illnesses. High-altitude myocardial injury (HAMI) usually occurs in people who suffered from high-altitude exposure. To date, the molecular mechanism of HAMI remains elusive, which seriously hinders the prevention and treatment of HAMI. L-carnitine and trimetazidine are classic cardiovascular protective medicines. In this study, we used the metabolomic method, based on GC/MS, to explore the changes in metabolites in rats exposed to high-altitude hypoxia and then illustrate the metabolic pathways associated with the modulatory effect of L-carnitine combined with trimetazidine on rats with high-altitude exposure. The results showed that metabolites in the myocardium in rats under high-altitude hypoxia were markedly changed, such as branched-chain amino acids (BCAA, leucine, isoleucine, and valine), taurine, succinic acid, fumaric acid, lactic acid, pyruvic acid, 3-hydroxybutyrate, and docosahexaenoic acid (DHA), while L-carnitine combined with trimetazidine modulated and improved the abnormal changes in energy substances caused by high-altitude hypoxia. L-carnitine mainly promoted the metabolism of fatty acids, while trimetazidine enhanced the glycolysis process. The combined administration of the two components not only increased the metabolism of fatty acids but also promoted aerobic glycolysis. Meanwhile, it contributed to the decrease in the elevation in some of the intermediates of the tricarboxylic acid (TCA) cycle, decrease in the production of 3-hydroxybutyric acid, and relief of the abnormal energy metabolism process in organisms and the cardiac tissue. Our analysis delineates the landscape of the metabolites in the myocardial tissue of rats that were exposed to high altitude. Moreover, L-carnitine combined with trimetazidine can relieve the HAMI through modulated and improved abnormal changes in energy substances caused by high-altitude hypoxia.

miR-17-5p Regulates Differential Expression of NCOA3 in Pig Intramuscular and Subcutaneous Adipose Tissue.

Fat distribution affects economic value in pork production. Intramuscular adipose tissue (IMAT) improves meat quality, whereas subcutaneous adipose tissue (SCAT) is usually regarded as waste. In the present study, we analyzed IMAT/SCAT (I/S) ratios in each pig. Individuals selected from a population of 1200 Suhuai pigs were divided into two cohorts; those with high I/S ratios and those with low I/S ratios, and correlations between nuclear Receptor Co-activator 3 (NCOA3), a critical gene involved in regulating fat accumulation, and fat distribution were investigated. The ratio of IMAT NCOA3 to SCAT NCOA3 expression levels (NCOA3I/NCOA3S) was higher in the high I/S group compared with the low I/S group. The NCOA3 expression level in fat tissue was positively correlated with fat deposition. miR-17-5p was identified as a putative regulator of NCOA3 based on bioinformatics prediction analysis followed by gene expression analysis. The miR-17-5pI/miR-17-5pS ratio was negatively correlated with the NCOA3I/NCOA3S ratio. The predicted relationship between miR-17-5p and NCOA3 was further verified by dual luciferase activity assays, qPCR, and western blots. Overexpression of miR-17-5p in intramuscular preadipocytes inhibited NCOA3 expression and reduced preadipocyte differentiation. FABP4 and PPARG expression were also significantly decreased, as was triglyceride content. Meanwhile, knockdown of miR-17-5p significantly increased NCOA3 expression and promoted intramuscular preadipocyte differentiation. Based on these results, we propose that differential expression of NCOA3 in pig intramuscular and subcutaneous adipose tissue is regulated by miR-17-5p.

Genetic variants in ABCA1 promoter affect transcription activity and plasma HDL level in pigs.

Excess accumulation of cholesterol in plasma may result in coronary artery disease. Numerous studies have demonstrated that ATP-binding cassette protein A1 (ABCA1) mediates the efflux of cholesterol and phospholipids to apolipoproteins, a process necessary for plasma high density lipoprotein (HDL) formation. Higher plasma levels of HDL are associated with lower risk for cardiovascular disease. Studies of human disease and animal models had shown that an increased hepatic ABCA1 activity relates to an enhanced plasma HDL level. In this study, we hypothesized that functional mutations in the ABCA1 promoter in pigs may affect gene transcription activity, and consequently the HDL level in plasma. The promoter region of ABCA1 was comparatively scanned by direct sequencing with pool DNA of high- and low-HDL groups (n=30 for each group). Two polymorphisms, c. - 608A>G and c. - 418T>A, were revealed with reverse allele distribution in the two groups. The two polymorphisms were completely linked and formed only G-A or A-T haplotypes when genotyped in a larger population (n=526). Furthermore, we found that the G-A/G-A genotype was associated with higher HDL and ABCA1 mRNA level than A-T/A-T genotype. Luciferase assay also revealed that G-A haplotype promoter had higher activity than A-T haplotype. Single-nucleotide mutant assay showed that c.-418T>A was the causal mutation for ABCA1 transcription activity alteration. Conclusively, we identified two completely linked SNPs in porcine ABCA1 promoter region which have influence on the plasma HDL level by altering ABCA1 gene transcriptional activity.