Cardiac Transcriptome Analysis Reveals Nr4a1 Mediated Glucose Metabolism Dysregulation in Response to High-Fat Diet

Cardiometabolic benefits of fenofibrate in heart failure related to obesity and diabetes

BACKGROUND

Heart failure (HF) is a serious and common condition affecting millions of people worldwide, with obesity being a major cause of metabolic disorders such as diabetes and cardiovascular disease. This study aimed to investigate the effects of fenofibrate, a peroxisome proliferator-activated receptor alpha (PPARα) agonist, on the obese- and diabetes-related cardiomyopathy.

METHODS AND RESULTS

We used db/db mice and high fat diet-streptozotocin induced diabetic mice to investigate the underlying mechanisms of fenofibrate's beneficial effects on heart function. Fenofibrate reduced fibrosis, and lipid accumulation, and suppressed inflammatory and immunological responses in the heart via TNF signaling. In addition, we investigated the beneficial effects of fenofibrate on HF hospitalization. The Korean National Health Insurance database was used to identify 427,154 fenofibrate users and 427,154 non-users for comparison. During the 4.22-year follow-up, fenofibrate use significantly reduced the risk of HF hospitalization (hazard ratio, 0.907; 95% CI 0.824-0.998).

CONCLUSIONS

The findings suggest that fenofibrate may be a useful therapeutic agent for obesity- and diabetes-related cardiomyopathy.

Transcriptome profiling of longissimus dorsi during different prenatal stages to identify genes involved in intramuscular fat deposition in lean and obese pig breeds

BACKGROUND

There was significant difference in muscle development between fat-type and lean-type pig breeds.

METHODS AND RESULTS

In current study, transcriptome analysis and bioinformatics analysis were used to compare the difference in longissimus dorsi (LD) muscle at three time-points (38 days post coitus (dpc), 58 dpc, and 78 dpc ) between Huainan (HN) and Large white (LW) pig breeds. A total of 24500 transcripts were obtained in 18 samples, and 2319, 2799, and 3713 differently expressed genes (DEGs) were identified between these two breeds at 38 dpc, 58 dpc, and 78 dpc, respectively. And the number and foldchange of DEGs were increased, the alternative splice also increased. The cluster analysis of DEGs indicated the embryonic development progress of LD muscle between these two breeds was different. There were 539 shared DEGs between HN and LW at three stages, and the top-shared DEGs were associated with muscle development and lipid deposition, such as KLF4, NR4A1, HSP70, ZBTB16 and so on.

CONCLUSIONS

The results showed DEGs between Huainan (HN) and Large white (LW) pig breeds, and contributed to the understanding the muscle development difference between HN and LW, and provided basic materials for improvement of meat quality.

Identification and subtype analysis of biomarkers associated with the solute carrier family in acute myocardial infarction

The dysregulation of some solute carrier (SLC) proteins has been linked to a variety of diseases, including diabetes and chronic kidney disease. However, SLC-related genes (SLCs) has not been extensively studied in acute myocardial infarction (AMI). The GSE66360 and GSE60993 datasets, and SLCs geneset were enrolled in this study. Differentially expressed SLCs (DE-SLCs) were screened by overlapping DEGs between the AMI and control groups and SLCs. Next, functional enrichment analysis was carried out to research the function of DE-SLCs. Consistent clustering of samples from the GSE66360 dataset was accomplished based on DE-SLCs selected. Next, the gene set enrichment analysis (GSEA) was performed on the DEGs-cluster (cluster 1 vs cluster 2). Three machine learning models were performed to obtain key genes. Subsequently, biomarkers were obtained through receiver operating characteristic (ROC) curves and expression analysis. Then, the immune infiltration analysis was performed. Afterwards, single-gene GSEA was carried out, and the biomarker-drug network was established. Finally, quantitative real-time fluorescence PCR (qRT-PCR) was performed to verify the expression levels of biomarkers. In this study, 13 DE-SLCs were filtered by overlapping 366 SLCs and 448 DEGs. The functional enrichment results indicated that the genes were implicated with amino acid transport and TNF signaling pathway. After the consistency clustering analysis, the samples were classified into cluster 1 and cluster 2 subtypes. The functional enrichment results showed that DEGs-cluster were implicated with chemokine signaling pathway and so on. Further, SLC11A1 and SLC2A3 were identified as SLC-related biomarkers, which had the strongest negative relationship with resting memory CD4 T cells and the strongest positive association with activated mast cells. In addition, the single-gene GSEA results showed that cytosolic ribosome was enriched by the biomarkers. Five drugs targeting SLC2A3 were predicted as well. Lastly, the experimental results showed that the biomarkers expression trends were consistent with public database. In this study, 2 SLC-related biomarkers (SLC11A1 and SLC2A3) were screened and drug predictions were carried out to explore the prediction and treatment of AMI.

Genetic inhibition of serum glucocorticoid kinase 1 prevents obesity-related atrial fibrillation

Obesity is an important risk factor for atrial fibrillation (AF), but a better mechanistic understanding of obesity-related atrial fibrillation is required. Serum glucocorticoid kinase 1 (SGK1) is a kinase positioned within multiple obesity-related pathways, and prior work has shown a pathologic role of SGK1 signaling in ventricular arrhythmias. We validated a mouse model of obesity-related AF using wild-type mice fed a high-fat diet. RNA sequencing of atrial tissue demonstrated substantial differences in gene expression, with enrichment of multiple SGK1-related pathways, and we showed upregulated of SGK1 transcription, activation, and signaling in obese atria. Mice expressing a cardiac specific dominant-negative SGK1 were protected from obesity-related AF, through effects on atrial electrophysiology, action potential characteristics, structural remodeling, inflammation, and sodium current. Overall, this study demonstrates the promise of targeting SGK1 in a mouse model of obesity-related AF.

Therapeutic potential of NR4A1 in cancer: Focus on metabolism

Metabolic reprogramming is a vital hallmark of cancer, and it provides the necessary energy and biological materials to support the continuous proliferation and survival of tumor cells. NR4A1 is belonging to nuclear subfamily 4 (NR4A) receptors. NR4A1 plays diverse roles in many tumors, including melanoma, colorectal cancer, breast cancer, and hepatocellular cancer, to regulate cell growth, apoptosis, metastasis. Recent reports shown that NR4A1 exhibits unique metabolic regulating effects in cancers. This receptor was first found to mediate glycolysis via key enzymes glucose transporters (GLUTs), hexokinase 2 (HK2), fructose phosphate kinase (PFK), and pyruvate kinase (PK). Then its functions extended to fatty acid synthesis by modulating CD36, fatty acid-binding proteins (FABPs), sterol regulatory element-binding protein 1 (SREBP1), glutamine by Myc, mammalian target of rapamycin (mTOR), and hypoxia-inducible factors alpha (HIF-1α), respectively. In addition, NR4A1 is involving in amino acid metabolism and tumor immunity by metabolic processes. More and more NR4A1 ligands are found to participate in tumor metabolic reprogramming, suggesting that regulating NR4A1 by novel ligands is a promising approach to alter metabolism signaling pathways in cancer therapy. Basic on this, this review highlighted the diverse metabolic roles of NR4A1 in cancers, which provides vital references for the clinical application.

Kallistatin/Serpina3c inhibits cardiac fibrosis after myocardial infarction by regulating glycolysis via Nr4a1 activation

BACKGROUND

Fibrotic remodeling is an essential aspect of heart failure. Human kallistatin (KS, mouse Serpina3c homologs) inhibits fibrosis after myocardial infarction (MI) but the specific underlying mechanism is unknown.

METHODS

A total of 40 heart failure patients (HFPs) were enrolled and their plasma KS was measured using ELISA. Serpina3c^-/- and C57BL/6 mice were used to construct the MI model. TGF-β1 or a hypoxic condition was established to interfere with the functioning of cardiac fibroblasts (CFs). RNA-seq was performed to assess the effect of Serpina3c on the transcriptome.

FINDINGS

The levels of KS were used as a predictor of readmission among the HFPs. Serpina3c expression decreased in MI hearts and CFs. Serpina3c^-/- led to the aggravation of MI fibrosis, and increased the proliferation of CFs. The overexpression of Serpina3c in CFs had the opposite effect. Glycolysis-related genes were significantly increased in Serpina3c^-/- group by RNA-seq. Enolase (ENO1), which is a key enzyme in glycolysis, increased most significantly. Inhibition of ENO1 could antagonize the promotion of Serpina3c^-/- on the proliferation of CFs. Co-IP was performed to verify the interaction between Serpina3c and Nr4a1. Serpina3c^-/- inhibited the acetylation of Nr4a1 and increased the degradation of Nr4a1. Activation of Nr4a1 could negatively regulate the expression of ENO1 and inhibited the proliferation of Serpina3c^-/- CFs in Serpina3c^-/- MI mice.

INTERPRETATION

Serpina3c inhibits the transcriptional activation of ENO1 by regulating the acetylation of Nr4a1, thereby reducing the fibrosis after MI by inhibiting glycolysis. Serpina3c is a potential target for prevention and treatment of heart failure after MI.

Proteomic and Structural Manifestations of Cardiomyopathy in Rat Models of Obesity and Weight Loss

Obesity cardiomyopathy increases the risk of heart failure and death. Obesity is curable, leading to the restoration of the heart phenotype, but it is not clear if there are any after-effects of obesity present after weight loss. We characterize the proteomic landscape of obesity cardiomyopathy with an evaluation of whether the cardiac phenotype is still shaped after weight loss. Cardiomyopathy was validated by cardiac hypertrophy, fibrosis, oversized myocytes, and mTOR upregulation in a rat model of cafeteria diet-induced developmental obesity. By global proteomic techniques (LC-MS/MS) a plethora of molecular changes was observed in the heart and circulation of obese animals, suggesting abnormal utilization of metabolic substrates. This was confirmed by increased levels of cardiac ACSL-1, a key enzyme for fatty acid degradation and decreased GLUT-1, a glucose transporter in obese rats. Calorie restriction and weight loss led to the normalization of the heart's size, but fibrosis was still excessive. The proteomic compositions of cardiac tissue and plasma were different after weight loss as compared to control. In addition to morphological consequences, obesity cardiomyopathy involves many proteomic changes. Weight loss provides for a partial repair of the heart's architecture, but the trace of fibrotic deposition and proteomic alterations may occur.