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Background: Little is known about the pathophysiological diversity of myocardial injury in type 2 diabetes mellitus (T2DM), but analyzing these differences is important for the accurate diagnosis and precise treatment of diabetic cardiomyopathy. This study aimed to elucidate the key cardiac pathophysiological differences in myocardial injury between obese and non-obese T2DM from mice to humans. Methods: Obese and non-obese T2DM mouse models were successfully constructed and observed until systolic dysfunction occurred. Changes in cardiac structure, function, energy metabolism and oxidative stress were assessed by biochemical and pathological tests, echocardiography, free fatty acids (FFAs) uptake fluorescence imaging, transmission electron microscopy, etc. Key molecule changes were screened and verified by RNA sequencing, quantitative real-time polymerase chain reaction and western blotting. Further, 28 human heart samples of healthy population and T2DM patients were collected to observe the cardiac remodeling, energy metabolism and oxidative stress adaptations as measured by pathological and immunohistochemistry tests. Results: Obese T2DM mice exhibited more severe cardiac structure remodeling and earlier systolic dysfunction than non-obese mice. Moreover, obese T2DM mice exhibited severe and persistent myocardial lipotoxicity, mainly manifested by increased FFAs uptake, accumulation of lipid droplets and glycogen, accompanied by continuous activation of the peroxisome proliferator activated receptor alpha (PPARα) pathway and phosphorylated glycogen synthase kinase 3 beta (p-GSK-3β), and sustained inhibition of glucose transport protein 4 (GLUT4) and adipose triglyceride lipase (ATGL), whereas non-obese mice showed no myocardial lipotoxicity characteristics at systolic dysfunction stage, accompanied by the restored PPARα pathway and GLUT4, sustained inhibition of p-GSK-3β and activation of ATGL. Additionally, both obese and non-obese T2DM mice showed significant accumulation of reactive oxygen species (ROS) when systolic dysfunction occurred, but the NF-E2-related factor 2 (Nrf2) pathway was significantly activated in obese mice, while was significantly inhibited in non-obese mice. Furthermore, the key differences found in animals were reliably verified in human samples. Conclusion: Myocardial injury in obese and non-obese T2DM may represent two different types of complications. Obese T2DM individuals, compared to non-obese individuals, are more prone to develop cardiac systolic dysfunction due to severe and persistent myocardial lipotoxicity. Additionally, anti-oxidative dysfunction may be a key factor leading to myocardial injury in non-obese T2DM.

Aims This study aims to investigate the pathophysiological role and mechanism of pigment epithelium-derived factor (PEDF) deletion in ovarian damage. Methods Female PEDF-knockout mice and their wild-type littermates were used in this study. Relevant tests were performed at 8–10 weeks or 32 weeks of age. Key findings Compared to the wild-type mice, the PEDF-knockout mice showed diminished ovarian reserve (DOR), worse ovum quality after injection to induce controlled ovarian stimulation, increased serum follicle stimulating hormone (FSH) level and an follicle stimulating hormone/luteinizing hormone (FSH/LH) ratio. Moreover, severe ovarian oxidative damage was found in ovaries of PEDF-knockout mice that mainly manifested as an accumulation of reactive oxygen species (ROS), NF‑E2-related factor 2 (Nrf2) pathway activation, significantly upregulated expression of ROS-generating genes. Correspondingly, the PEDF-knockout mice exhibited lipid metabolism disorder and insulin resistance, which mainly manifested as obesity, abdominal fat accumulation, adipocyte enlargement, severe ectopic fat deposition, dyslipidemia, changes in adipokine levels, hyperglycemia, hyperinsulinemia, impaired glucose tolerance, impaired insulin tolerance and significantly declined protein kinase B (Akt) phosphorylation levels. Significance Loss of PEDF leads to ovarian oxidative damage accompanied by DOR in mice, this is related to PEDF deficiency induced severe insulin resistance and lipid metabolism disorder. Therefore, PEDF may be a potential target for the treatment of diseases related to ovarian oxidative damage.

Melatonin (N-acetyl-5-methoxytryptamine) plays important roles in the regulation of development and the response to biotic and abiotic stresses in plants. Serotonin-N-acetyltransferase (SNAT) functions as a key catalytic enzyme involved in melatonin biosynthesis. In this study, the candidate gene VvSNAT1 (SNAT isogene) was isolated from grape (Vitis vinifera L. cv. Merlot). Tissue-specific expression and external treatment revealed that VvSNAT1 is a salt-inducible gene that is highly expressed in leaves. Subcellular localisation results revealed that VvSNAT1 was located in the chloroplasts, which is similar to other plant SNAT proteins. Ectopic overexpression of VvSNAT1 in Arabidopsis resulted in increased melatonin production and salt tolerance. Transgenic Arabidopsis overexpressing VvSNAT1 exhibited enhanced growth and physiological performance, including a lower degree of leaf wilting, higher germination rate, higher fresh weight, and longer root length under salt stress. Moreover, overexpression of VvSNAT1 in Arabidopsis protected cells from oxidative damage by reducing the accumulation of malondialdehyde (MDA) and hydrogen peroxide (H2O2). These results indicate that VvSNAT1 positively responds to salt stress. Our results provide a novel perspective for VvSNAT1 to improve salt tolerance, mediated by melatonin accumulation, plant growth promotion and oxidative damage reduction.

Aims: Lack of cardiac regeneration with robust fibrosis response to the acute myocardial injury is the main obstacle to clinical treatment of cardiovascular diseases in humans. Stimulating the proliferation of endogenous cardiomyocytes (CMs) and replacing the scarred tissue with new functional CMs is a potential therapeutic strategy to the patients with heart failure. Heart rate reduction (HRR) is regarded as an effective clinical treatment for myocardial infarction. However, the mechanism of HRR promoting the recovery of cardiac function after injury still remains controversial, and whether there is any endogenous CM proliferation induced by HRR is undefined. Methods and results: The beating of CMs was reduced in vitro and heart rate (HR) of adult mice and different animal models of myocardial injury were modulated by six antiarrhythmic drugs to determine the role of HR in CM proliferation and cardiac repair. RNA-seq, extracellular flux analysis, metabolic flux analysis, and metabonomics were used to study the CM metabolism after HR modulation. We verified that reducing the beating can induce CM proliferation both in vitro and in vivo physiologically, and HRR also promoted cardiac regenerative repair after myocardial injury as well, reversely, increasing HR showed the opposite effect. Mechanistically, HRR reduced energy metabolism requirements and total ATP production of CMs but switched energy metabolic mode that the proportion of ATP production from aerobic glycolysis was increased, while from fatty acid oxidation was decreased. The switching of energy metabolic mode in CMs occurred in synchrony with the changes of glycolytic enzymes activities, these enzymes, including PFKFB3, PKM2, GAPDH, induced G1/S transition for cell cycle re-entry of CMs by upregulating the expression of cyclin D and CDK4/6 and facilitate substrates into the biomass needed to produce a new cell by biosynthesis. This coordinating function of glycolytic enzymes contributed to CM proliferation. Conclusion: Together, these results demonstrate that reduction of heart rate promotes CM proliferation by switching the energy metabolic mode, and highlight the potential therapeutic role of HRR in regenerative medicine.

Background Endothelial cell injury, induced by dyslipidemia, is the initiation of atherosclerosis, resulting in an imbalance in endothelial fatty acid ( FA ) transport. Pigment epithelial‐derived factor ( PEDF ) is an important regulator in lipid metabolism. We hypothesized that PEDF is involved in endothelium‐mediated FA uptake under hyperlipidemic conditions. Methods and Results Circulating PEDF levels were higher in patients with atherosclerotic cardiovascular disease than in normal individuals. However, decreasing trends of serum PEDF levels were confirmed in both wild‐type and apolipoprotein E–deficient mice fed a long‐term high‐fat diet. Apolipoprotein E–deficient/PEDF‐deficient mice were generated by crossing PEDF‐deficient mice with apolipoprotein E–deficient mice, and then mice were fed with 24, 36, or 48 weeks of high‐fat diet. Greater increases in body fat and plasma lipids were displayed in PEDF ‐deficient mice. In addition, PEDF deficiency in mice accelerated atherosclerosis, as evidenced by increased atherosclerotic plaques, pronounced vascular dysfunction, and increased lipid accumulation in peripheral tissues, whereas injection of adeno‐associated virus encoding PEDF exerted opposite effects. Mechanistically, PEDF inhibited the vascular endothelial growth factor B paracrine signaling by reducing secretion of protein vascular endothelial growth factor B in peripheral tissue cells and decreasing expression of its downstream targets in endothelial cells, including its receptors (namely, vascular endothelial growth factor receptor‐1 and neuropilin‐1), and FA transport proteins 3 and 4, to suppress endothelial FA uptake, whereas PEDF deletion in mice activated the vascular endothelial growth factor B signaling pathway, thus causing markedly increased lipid accumulation. Conclusions Decreasing expression of PEDF aggravates atherosclerosis by significantly impaired vascular function and enhanced endothelial FA uptake, thus exacerbating ectopic lipid deposition in peripheral tissues.

Background: Pigment epithelial-derived factor (PEDF) is protectively involved in atherosclerosis induced by hyperlipidemia, but expression characteristics of PEDF and the role of PEDF in the later stage of progressive atherosclerosis remain unclear. Methods: Circulating PEDF were analyzed in patients with atherosclerotic cardiovascular disease (ASCVD) and in murine models of wildtype (WT) mice and ApoE-/- mice under long-term high-fat diet (HFD). PEDF-/-/ ApoE-/- mice and matching PEDF+/+/ ApoE-/- mice fed with HFD for 24, 36 and 48 weeks, combined with injections of adeno-associated virus encoding PEDF (AAV-PEDF) in ApoE-/-/PEDF-/- mice were used to investigate the effects of PEDF knockdown on vascular function and structure. Experiments in vitro and in vivo were applied to identify PEDF regulate vascular endothelial growth factor (VEGFB) signaling pathway mediated endothelial fatty acid (FA) uptake. Findings: Circulating PEDF was increased in ASCVD patients compared to normal individuals, while decreasing trends were confirmed in murine models of WT mice and ApoE-/- mice on long-term HFD. ApoE-/-/PEDF-/- mice placed on HFD were fatter and had accelerated atherosclerotic formation, as evidenced by higher serum lipid levels, increased atherosclerotic plaques, pronounced vascular dysfunction and increased lipid accumulation in peripheral tissues, whereas injections of AAV-PEDF in ApoE-/-/PEDF-/- mice significantly improved. Mechanistically, PEDF deletion activated VEGFB paracrine signaling by upregulating expressions of VEGFB in peripheral tissues and its downstream targets on endothelial cells, including its receptors, namely VEGFR1 and neuropilin-1, and fatty acid transport protein 3 and 4 to enhance FA uptake. Interpretation: Decreasing expression of PEDF may decompensate to aggravate atherosclerosis. Funding: National Nature Science Foundation of China, Science and Technology Project of Guangzhou. Declaration of Interest: The authors declare no conflict of interest. Ethical Approval: The study was approved by the ethical committees of Sun Yat-sen Memorial Hospital and Sun Yat-sen University.