Peroxisome proliferator-activated receptor-gamma coactivator 1-alpha overexpression prevents endothelial apoptosis by increasing ATP/ADP translocase activity

Cellular metabolism changes in atherosclerosis and the impact of comorbidities

Cell activation and nutrient dysregulation are common consequences of atherosclerosis and its preceding risk factors, such as hypertension, dyslipidemia, and diabetes. These diseases may also impact cellular metabolism and consequently cell function, and the other way around, altered cellular metabolism can impact disease development and progression through altered cell function. Understanding the contribution of altered cellular metabolism to atherosclerosis and how cellular metabolism may be altered by co-morbidities and atherosclerosis risk factors could support the development of novel strategies to lower the risk of CVD. Therefore, we briefly review disease pathogenesis and the principles of cell metabolic pathways, before detailing changes in cellular metabolism in the context of atherosclerosis and comorbidities. In the hypoxic, inflammatory and hyperlipidemic milieu of the atherosclerotic plaque riddled with oxidative stress, metabolism shifts to increase anaerobic glycolysis, the pentose-phosphate pathway and amino acid use. We elaborate on metabolic changes for macrophages, neutrophils, vascular endothelial cells, vascular smooth muscle cells and lymphocytes in the context of atherosclerosis and its co-morbidities hypertension, dyslipidemia, and diabetes. Since causal relationships of specific key genes in a metabolic pathway can be cell type-specific and comorbidity-dependent, the impact of cell-specific metabolic changes must be thoroughly explored in vivo, with a focus on also systemic effects. When cell-specific treatments become feasible, this information will be crucial for determining the best metabolic intervention to improve atherosclerosis and its interplay with co-morbidities.

1,2,4-Triazole benzamide derivative TPB against Gaeumannomyces graminis var. tritici as a novel dual-target fungicide inhibiting ergosterol synthesis and adenine nucleotide transferase function

BACKGROUND

Isopropyl 4-(2-chloro-6-(1H-1,2,4-triazol-1-yl)benzamido)benzoate (TPB) was a 1,2,4-triazole benzoyl arylamine derivative with excellent antifungal activity, especially against Gaeumannomyces graminis var. tritici (Ggt). Its mechanism of action was investigated by transmission electron microscopy (TEM) observation, assays of sterol composition, cell membrane permeability, intracellular ATP and mitochondrial membrane potential, and mPTP permeability, ROS measurement, RNA sequencing (RNA-seq) analysis.

RESULTS

TPB interfered with ergosterol synthesis, reducing ergosterol content, increasing toxic intermediates, and finally causing biomembrane disruption such as increasing cell membrane permeability and content leakage, and destruction of organelle membranes such as coarse endoplasmic reticulum and vacuole. Moreover, TPB destroyed the function of adenine nucleotide transferase (ANT), leading to ATP transport obstruction in mitochondria, inhibiting mPTP opening, inducing intracellular ROS accumulation and mitochondrial membrane potential loss, finally resulting in mitochondrial damage including mitochondria swelled, mitochondrial membrane dissolved, and cristae destroyed and reduced. RNA-seq analyses showed that TPB increased the expression of ERG11, ERG24, ERG6, ERG5, ERG3 and ERG2 genes in ergosterol synthesis pathway, interfered with the expression of genes (NDUFS5, ATPeV0E, NCA2 and Pam17) related to mitochondrial structure, and inhibited the expression of genes (WrbA and GST) related to anti-oxidative stress.

CONCLUSIONS

TPB exhibited excellent antifungal activity against Ggt by inhibiting ergosterol synthesis and destroying ANT function. So, TPB was a novel compound with dual-target mechanism of action and can be considered a promising novel fungicide for the control of wheat Take-all. The results provided new guides for the structural design of active compounds and powerful tools for pathogen resistance management. © 2023 Society of Chemical Industry.

Peroxisome proliferator-activated receptor gamma coactivator-1 (PGC-1) family in physiological and pathophysiological process and diseases

Peroxisome proliferator-activated receptor gamma coactivator-1 (PGC-1) family (PGC-1s), consisting of three members encompassing PGC-1α, PGC-1β, and PGC-1-related coactivator (PRC), was discovered more than a quarter-century ago. PGC-1s are essential coordinators of many vital cellular events, including mitochondrial functions, oxidative stress, endoplasmic reticulum homeostasis, and inflammation. Accumulating evidence has shown that PGC-1s are implicated in many diseases, such as cancers, cardiac diseases and cardiovascular diseases, neurological disorders, kidney diseases, motor system diseases, and metabolic disorders. Examining the upstream modulators and co-activated partners of PGC-1s and identifying critical biological events modulated by downstream effectors of PGC-1s contribute to the presentation of the elaborate network of PGC-1s. Furthermore, discussing the correlation between PGC-1s and diseases as well as summarizing the therapy targeting PGC-1s helps make individualized and precise intervention methods. In this review, we summarize basic knowledge regarding the PGC-1s family as well as the molecular regulatory network, discuss the physio-pathological roles of PGC-1s in human diseases, review the application of PGC-1s, including the diagnostic and prognostic value of PGC-1s and several therapies in pre-clinical studies, and suggest several directions for future investigations. This review presents the immense potential of targeting PGC-1s in the treatment of diseases and hopefully facilitates the promotion of PGC-1s as new therapeutic targets.

GLP-1RAs and cardiovascular disease: is the endothelium a relevant platform?

Hyperglycemia strongly affects endothelial function and activation, which in turn increases the risk of atherosclerotic cardiovascular disease. Among pharmacotherapies aimed at lowering blood glucose levels, glucagon-like peptide 1 receptor agonists (GLP-1RA) represent a class of drugs involved in the improvement of the endothelium damage and the progression of cardiovascular diseases. They show antihypertensive and antiatherosclerotic actions due at least in part to direct favorable actions on the coronary vascular endothelium, such as oxidative stress reduction and nitric oxide increase. However, cumulative peripheral indirect actions could also contribute to the antiatherosclerotic functions of GLP-1/GLP-1R agonists, including metabolism and gut microbiome regulation. Therefore, further research is necessary to clarify the specific role of this drug class in the management of cardiovascular disease and to identify specific cellular targets involved in the protective signal transduction. In the present review, we provide an overview of the effects of GLP-1RAs treatment on cardiovascular disease with particular attention on potential molecular mechanisms involving endothelium function on formation and progression of atherosclerotic plaque.

Heme-oxygenase and lipid mediators in obesity and associated cardiometabolic diseases: Therapeutic implications

Obesity-mediated metabolic syndrome remains the leading cause of death worldwide. Among many potential targets for pharmacological intervention, a promising strategy involves the heme oxygenase (HO) system, specifically its inducible form, HO-1. This review collects and updates much of the current knowledge relevant to pharmacology and clinical medicine concerning HO-1 in metabolic diseases and its effect on lipid metabolism. HO-1 has pleotropic effects that collectively reduce inflammation, while increasing vasodilation and insulin and leptin sensitivity. Recent reports indicate that HO-1 with its antioxidants via the effect of bilirubin increases formation of biologically active lipid metabolites such as epoxyeicosatrienoic acid (EET), omega-3 and other polyunsaturated fatty acids (PUFAs). Similarly, HO-1and bilirubin are potential therapeutic targets in the treatment of fat-induced liver diseases. HO-1-mediated upregulation of EET is capable not only of reversing endothelial dysfunction and hypertension, but also of reversing cardiac remodeling, a hallmark of the metabolic syndrome. This process involves browning of white fat tissue (i.e. formation of healthy adipocytes) and reduced lipotoxicity, which otherwise will be toxic to the heart. More importantly, this review examines the activity of EET in biological systems and a series of pathways that explain its mechanism of action and discusses how these might be exploited for potential therapeutic use. We also discuss the link between cardiac ectopic fat deposition and cardiac function in humans, which is similar to that described in obese mice and is regulated by HO-1-EET-PGC1α signaling, a potent negative regulator of the inflammatory adipokine NOV.

Adenine Nucleotide Translocase 1 Expression Modulates the Immune Response in Ischemic Hearts

Adenine nucleotide translocase 1 (ANT1) transfers ATP and ADP over the mitochondrial inner membrane and thus supplies the cell with energy. This study analyzed the role of ANT1 in the immune response of ischemic heart tissue. Ischemic ANT1 overexpressing hearts experienced a shift toward an anti-inflammatory immune response. The shift was characterized by low interleukin (IL)-1β expression and M1 macrophage infiltration, whereas M2 macrophage infiltration and levels of IL-10, IL-4, and transforming growth factor (TGFβ) were increased. The modulated immune response correlated with high mitochondrial integrity, reduced oxidative stress, low left ventricular end-diastolic heart pressure, and a high survival rate. Isolated ANT1-transgenic (ANT1-TG) cardiomyocytes expressed low levels of pro-inflammatory cytokines such as IL-1α, tumor necrosis factor α, and TGFβ. However, they showed increased expression and cellular release of anti-inflammatory immunomodulators such as vascular endothelial growth factor. The secretome from ANT1-TG cardiomyocytes initiated stress resistance when applied to ischemic wild-type cardiomyocytes and endothelial cells. It additionally prevented macrophages from expressing pro-inflammatory cytokines. Additionally, ANT1 expression correlated with genes that are related to cytokine and growth factor pathways in hearts of patients with ischemic cardiomyopathy. In conclusion, ANT1-TG cardiomyocytes secrete soluble factors that influence ischemic cardiac cells and initiate an anti-inflammatory immune response in ischemic hearts.

Twist1 signaling in age-dependent decline in angiogenesis and lung regeneration

Angiogenesis – the formation of new blood capillaries- is impaired in aging animals and contributes to the pathogenesis of age-related diseases. A transcription factor, Twist1, contributes to the pathogenesis of age- and angiogenesis-related diseases such as pulmonary fibrosis and atherosclerosis. However, the mechanism by which Twist1 controls age-dependent decline in angiogenesis remains unclear. In this report, we have demonstrated that the levels of Twist1 are higher, while the expression of peroxisome proliferator-activated receptor gamma coactivator 1-alpha (PGC1α) that stimulates angiogenesis, is lower in endothelial cells (ECs) isolated from aged human adipose tissues and mouse lungs compared to those from young tissues. Knockdown of Twist1 in aged human ECs increases the levels of PGC1α and angiogenic factor receptor, vascular endothelial growth factor receptor (VEGFR2), and restores EC proliferation and migration, while inhibition of PGC1α suppresses these effects. Knockdown of Twist1 in supplemented aged ECs also restores vascular networks in the subcutaneously implanted gel, while these effects are abrogated by knockdown of PGC1α. Age-dependent inhibition of post-pneumonectomy (PNX) lung growth is suppressed in Tie2-specific Twist1 conditional knockout mouse lungs, in which VEGFR2 expression increases after PNX. These results suggest that upregulation of endothelial Twist1 mediates age-dependent decline in angiogenesis and regenerative lung growth.

From Mitochondria to Atherosclerosis: The Inflammation Path

Inflammation is a key process in metazoan organisms due to its relevance for innate defense against infections and tissue damage. However, inflammation is also implicated in pathological processes such as atherosclerosis. Atherosclerosis is a chronic inflammatory disease of the arterial wall where unstable atherosclerotic plaque rupture causing platelet aggregation and thrombosis may compromise the arterial lumen, leading to acute or chronic ischemic syndromes. In this review, we will focus on the role of mitochondria in atherosclerosis while keeping inflammation as a link. Mitochondria are the main source of cellular energy. Under stress, mitochondria are also capable of controlling inflammation through the production of reactive oxygen species (ROS) and the release of mitochondrial components, such as mitochondrial DNA (mtDNA), into the cytoplasm or into the extracellular matrix, where they act as danger signals when recognized by innate immune receptors. Primary or secondary mitochondrial dysfunctions are associated with the initiation and progression of atherosclerosis by elevating the production of ROS, altering mitochondrial dynamics and energy supply, as well as promoting inflammation. Knowing and understanding the pathways behind mitochondrial-based inflammation in atheroma progression is essential to discovering alternative or complementary treatments.

Bach1 plays an important role in angiogenesis through regulation of oxidative stress

Bach1 is a known transcriptional repressor of the heme oxygenase-1 (HO-1) gene. The purpose of this study was to determine whether angiogenesis is accelerated by genetic ablation of Bach1 in a mouse ischemic hindlimb model. Hindlimb ischemia was surgically induced in wild-type (WT) mice, Bach1-deficient (Bach1-/-) mice, apolipoprotein E-deficient (ApoE-/-) mice, and Bach1/ApoE double-knockout (Bach1-/-/ApoE-/-) mice. Blood flow recovery after hindlimb ischemia showed significant improvement in Bach1-/- mice compared with that in WT mice. Bach1-/-/ApoE-/- mice showed significantly improved blood flow recovery compared with that in ApoE-/- mice to the level of that in WT mice. Migration of endothelial cells in ApoE-/- mice was significantly decreased compared with that in WT mice. Migration of endothelial cells significantly increased in Bach1-/-/ApoE-/- mice compared with that in ApoE-/- mice to the level of that in WT mice. The expression levels of HO-1, peroxisome proliferator-activated receptor γ co-activator-1α, angiopoietin 1, and fibroblast growth factor 2 in endothelial cells isolated from Bach1-/-/ApoE-/- mice were significantly higher than those in ApoE-/- mice. Oxidative stress assessed by anti-acrolein antibody staining in ischemic tissues and urinary 8-isoPGF2α excretion were significantly increased in ApoE-/- mice compared with those in WT and Bach1-/- mice. Oxidative stress was reduced in Bach1-/-/ApoE-/- mice compared with that in ApoE-/- mice. These findings suggest that genetic ablation of Bach1 plays an important role in ischemia-induced angiogenesis under the condition of increased oxidative stress. Bach1 could be a potential therapeutic target to reduce oxidative stress and potentially improve angiogenesis for patients with peripheral arterial disease.

LncRNA FENDRR Inhibits ox-LDL Induced Mitochondrial Energy Metabolism Disorder in Aortic Endothelial Cells via miR-18a-5p/PGC-1α Signaling Pathway

Atherosclerosis (AS) is the main cause of morbidity and mortality in the world. Mitochondrial dysfunction is closely related to AS. At present, several signaling pathways related to mitochondrial dysfunction have been found, one of which is around PGC-1α. PGC-1α is a transcription activator, which is related to mitochondrial biogenesis and antioxidant defense. In this study, we explored the effect of miR-18a-5p/PGC-1α signaling pathway on mitochondrial energy metabolism in HAECs with ox-LDL treatment. The results showed that the mitochondrial energy metabolism disorder in HAECs treated by ox-LDL was related to the downregulation of LncRNA FENDRR and PGC-1α. FENDRR could reverse ox-LDL induced mitochondrial energy metabolism disorder and upregulate the PGC-1α expression. FENDRR could be used as ceRNA to inhibit the miR-18a-5p expression and reduce the negative regulation of miR-18a-5p on PGC-1α. Downregulation of miR-18a-5p expression or upregulation of PGC-1α in ox-LDL treated HAECs could reverse mitochondrial energy metabolism disorder. In conclusion, these findings suggested that FENDRR/miR-18a-5p/PGC-1α signaling pathway regulated mitochondrial energy metabolism in HAECs; ox-LDL downregulated the expression of PGC-1α and cause mitochondrial energy metabolism disorder by inhibiting this signal pathway.

Genome-wide adaptive evolution to underground stresses in subterranean mammals: Hypoxia adaption, immunity promotion, and sensory specialization

Life underground has provided remarkable examples of adaptive evolution in subterranean mammals; however, genome-wide adaptive evolution to underground stresses still needs further research. There are approximately 250 species of subterranean mammals across three suborders and six families. These species not only inhabit hypoxic and dark burrows but also exhibit evolved adaptation to hypoxia, cancer resistance, and specialized sensory systems, making them an excellent model of evolution. The adaptive evolution of subterranean mammals has attracted great attention and needs further study. In the present study, phylogenetic analysis of 5,853 single-copy orthologous gene families of five subterranean mammals (Nannospalax galili, Heterocephalus glaber, Fukomys damarensis, Condylura cristata, and Chrysochloris asiatica) showed that they formed fou distinct clusters. This result is consistent with the traditional systematics of these species. Furthermore, comparison of the high-quality genomes of these five subterranean mammalian species led to the identification of the genomic signatures of adaptive evolution. Our results show that the five subterranean mammalian did not share positively selected genes but had similar functional enrichment categories, including hypoxia tolerance, immunity promotion, and sensory specialization, which adapted to the environment of underground stresses. Moreover, variations in soil hardness, climate, and lifestyles have resulted in different molecular mechanisms of adaptation to the hypoxic environment and different degrees of visual degradation. These results provide insights into the genome-wide adaptive evolution to underground stresses in subterranean mammals, with special focus on the characteristics of hypoxia adaption, immunity promotion, and sensory specialization response to the life underground.

PGC-1α, Inflammation, and Oxidative Stress: An Integrative View in Metabolism

Peroxisome proliferator-activated receptor-γ coactivator (PGC)-1α is a transcriptional coactivator described as a master regulator of mitochondrial biogenesis and function, including oxidative phosphorylation and reactive oxygen species detoxification. PGC-1α is highly expressed in tissues with high energy demands, and it is clearly associated with the pathogenesis of metabolic syndrome and its principal complications including obesity, type 2 diabetes mellitus, cardiovascular disease, and hepatic steatosis. We herein review the molecular pathways regulated by PGC-1α, which connect oxidative stress and mitochondrial metabolism with inflammatory response and metabolic syndrome. PGC-1α regulates the expression of mitochondrial antioxidant genes, including manganese superoxide dismutase, catalase, peroxiredoxin 3 and 5, uncoupling protein 2, thioredoxin 2, and thioredoxin reductase and thus prevents oxidative injury and mitochondrial dysfunction. Dysregulation of PGC-1α alters redox homeostasis in cells and exacerbates inflammatory response, which is commonly accompanied by metabolic disturbances. During inflammation, low levels of PGC-1α downregulate mitochondrial antioxidant gene expression, induce oxidative stress, and promote nuclear factor kappa B activation. In metabolic syndrome, which is characterized by a chronic low grade of inflammation, PGC-1α dysregulation modifies the metabolic properties of tissues by altering mitochondrial function and promoting reactive oxygen species accumulation. In conclusion, PGC-1α acts as an essential node connecting metabolic regulation, redox control, and inflammatory pathways, and it is an interesting therapeutic target that may have significant benefits for a number of metabolic diseases.

PGC-1α, a potential therapeutic target against kidney aging

Aging is defined as changes in an organism over time. The proportion of the aged population is markedly increasing worldwide. The kidney, as an essential organ with a high energy requirement, is one of the most susceptible organs to aging. It is involved in glucose metabolism via gluconeogenesis, glucose filtration and reabsorption, and glucose utilization. Proximal tubular epithelial cells (PTECs) depend on lipid metabolism to meet the high demand for ATP. Recent studies have shown that aging‐related kidney dysfunction is highly associated with metabolic changes in the kidney. Peroxisome proliferator‐activated receptor gamma coactivator‐1 alpha (PGC‐1α), a transcriptional coactivator, plays a major role in the regulation of mitochondrial biogenesis, peroxisomal biogenesis, and glucose and lipid metabolism. PGC‐1α is abundant in tissues, including kidney PTECs, which demand high energy. Many in vitro and in vivo studies have demonstrated that the activation of PGC‐1α by genetic or pharmacological intervention prevents telomere shortening and aging‐related changes in the skeletal muscle, heart, and brain. The activation of PGC‐1α can also prevent kidney dysfunction in various kidney diseases. Therefore, a better understanding of the effect of PGC‐1α activation in various organs on aging and kidney diseases may unveil a potential therapeutic strategy against kidney aging.

Endothelial mitochondrial senescence accelerates cardiovascular disease in antiretroviral-receiving HIV patients

Combination antiretroviral therapy (cART) has been hugely successful in reducing the mortality associated with human immunodeficiency virus (HIV) infection, resulting in a growing population of people living with HIV (PLWH). Since PLWH now have a longer life expectancy, chronic comorbidities have become the focus of the clinical management of HIV. For example, cardiovascular complications are now one of the most prevalent causes of death in PLWH. Numerous epidemiological studies show that antiretroviral treatment increases cardiovascular disease (CVD) risk and early onset of CVD in PLWH. Nucleoside reverse transcriptase inhibitors (NRTIs) are the backbone of cART, and two NRTIs are typically used in combination with one drug from another drug class, e.g., a fusion inhibitor. NRTIs are known to induce mitochondrial dysfunction, contributing to toxicity in numerous tissues, such as myopathy, lipoatrophy, neuropathy, and nephropathy. In in vitro studies, short-term NRTI treatment induces an endothelial dysfunction with an increased reactive oxygen species (ROS) production; long-term NRTI treatment decreases cell replication capacity, while increasing mtROS production and senescent cell accumulation. These findings suggest that a mitochondrial oxidative stress is involved in the pathogenesis of NRTI-induced endothelial dysfunction and premature senescence. Mitochondrial dysfunction, defined by a compromised mitochondrial quality control via biogenesis and mitophagy, has a causal role in premature endothelial senescence and can potentially initiate early cardiovascular disease (CVD) development in PLWH. In this review, we explore the hypothesis and present literature supporting that long-term NRTI treatment induces vascular dysfunction by interfering with endothelial mitochondrial homeostasis and provoking mitochondrial genomic instability, resulting in premature endothelial senescence.

Peroxisome Proliferator-Activated Receptor-γ Coactivator-1α Inhibits Vascular Calcification Through Sirtuin 3-Mediated Reduction of Mitochondrial Oxidative Stress

Aims: Vascular calcification is associated with cardiovascular death in patients with chronic kidney disease (CKD). Peroxisome proliferator-activated receptor-γ coactivator-1α (PGC-1α) plays an important role in various cardiovascular diseases. However, its role in vascular calcification remains unknown. Results: Adenine-induced rat CKD model was used to induce arterial medial calcification. The level of PGC-1α decreased in abdominal aorta of CKD rats. Overexpression of PGC-1α significantly ameliorated calcium deposition in rat abdominal aorta, isolated carotid rings, and cultured vascular smooth muscle cells (VSMCs). Mitochondrial reactive oxygen species (mtROS) increased in calcifying aorta and VSMCs. Upregulation of PGC-1α inhibited, whereas PGC-1α depletion promoted β-glycerophosphate-induced mtROS production and calcium deposition. Moreover, PGC-1α increased superoxide dismutase 1 (SOD1) and SOD2 contents in vivo and in vitro, whereas SOD2 deletion eliminated PGC-1α-mediated mtROS change and promoted calcium deposition. Mechanistically, sirtuin 3 (SIRT3) expression declined in calcifying aorta and VSMCs, while PGC-1α overexpression restored SIRT3 expression. Inhibition of SIRT3 by 3-TYP or siRNA (small interfering RNA) reduced PGC-1α-induced upregulation of SOD1 and SOD2, and abolished the protective effect of PGC-1α on calcification of VSMCs. Importantly, PGC-1α was reduced in calcified femoral arteries in CKD patients. In phosphate-induced human umbilical arterial calcification, upregulation of PGC-1α attenuated calcium nodule formation, while this protective effect was abolished by SIRT3 inhibitor. Innovation: We showed for the first time that PGC-1α is an important endogenous regulator against vascular calcification. Induction of PGC-1α could be a potential strategy to treat vascular calcification in CKD patients. Conclusions: PGC-1α protected against vascular calcification by SIRT3-mediated mtROS reduction.

Mitochondrial Dysfunction in Atherosclerosis

Mitochondria are highly dynamic organelles beyond powerhouses of a cell. These components also play important roles in cell homeostasis by regulating cell function and phenotypic modulation. Atherosclerosis is the leading cause of morbidity and mortality in developed and developing countries. Mitochondrial dysfunction has been increasingly associated with the initiation and progression of atherosclerosis by elevating the production of reactive oxygen species and mitochondrial oxidative stress damage, mitochondrial dynamics dysfunction, and energy supply. In this review, we describe the progression of the link between mitochondrial dysfunction and atherosclerosis and its potential regulation mechanisms.

Weighted gene co-expression network analysis to explain the relationship between plasma total carotenoids and lipid profile

Background

Variability in circulating carotenoids may be attributable to several factors including, among others, genetic variants and lipid profile. However, relatively few studies have considered the impact of gene expression in the inter-individual variability in circulating carotenoids. Most studies considered expression of genes individually and ignored their high degree of interconnection. Weighted gene co-expression network analysis (WGCNA) is a systems biology method used for finding gene clusters with highly correlated expression levels and for relating them to phenotypic traits. The objective of the present observational study is to examine the relationship between plasma total carotenoid concentrations and lipid profile using WGCNA.

Results

Whole blood expression levels of 533 probes were associated with plasma total carotenoids. Among the four WGCNA distinct modules identified, turquoise, blue, and brown modules correlated with plasma high-density lipoprotein cholesterol (HDL-C) and total cholesterol. Probes showing a strong association with HDL-C and total cholesterol were also the most important elements of the brown and blue modules. A total of four and 29 hub genes associated with total carotenoids were potentially related to HDL-C and total cholesterol, respectively.

Conclusions

Expression levels of 533 probes were associated with plasma total carotenoid concentrations. Using WGCNA, four modules and several hub genes related to lipid and carotenoid metabolism were identified. This integrative analysis provides evidence for the potential role of gene co-expression in the relationship between carotenoids and lipid concentrations. Further studies and validation of the hub genes are needed.

Electronic supplementary material

The online version of this article (10.1186/s12263-019-0639-5) contains supplementary material, which is available to authorized users.

Central role of obesity in endothelial cell dysfunction and cardiovascular risk

SUMMARY Atherosclerosis is the leading cause of mortality in the contemporary world. The critical role of the endothelial cells (EC) in vascular homeostasis, the metabolic changes that take place when the cell is activated, and the elements involved in these processes have been widely explored over the past years. Obesity and its impact, promoting a rise in blood levels of free fatty acids (FAs) are often associated with atherosclerosis and cardiovascular mortality. However, the mechanisms that promote cardiovascular structural changes and adaptive changes in the ECs, particularly in the context of obesity, are little known. Here, we reviewed studies that assessed the metabolic adaptations of healthy and dysfunctional ECs during exposure to FAs, as well as the epidemiological perspectives of cardiovascular structural changes in obesity. Finally, we explored the role of new agents – sphingolipids, dietary unsaturated fatty acids and sodium-glucose cotransporter-2 inhibitors (iSGLT2) – in atherosclerosis and their relationship with obesity.

Endothelial Cell Metabolism in Atherosclerosis

Atherosclerosis and its sequelae, such as myocardial infarction and stroke, are the leading cause of death worldwide. Vascular endothelial cells (EC) play a critical role in vascular homeostasis and disease. Atherosclerosis as well as its independent risk factors including diabetes, obesity, and aging, are hallmarked by endothelial activation and dysfunction. Metabolic pathways have emerged as key regulators of many EC functions, including angiogenesis, inflammation, and barrier function, processes which are deregulated during atherogenesis. In this review, we highlight the role of glucose, fatty acid, and amino acid metabolism in EC functions during physiological and pathological states, specifically atherosclerosis, diabetes, obesity and aging.

YAP1-TEAD1 signaling controls angiogenesis and mitochondrial biogenesis through PGC1α

Mitochondria contribute to key processes of cellular function, while mitochondrial dysfunction is implicated in metabolic disorders, neurodegenerative diseases, and cardiovascular diseases, in which angiogenesis - the formation of new blood capillaries - is dysregulated. The Hippo signaling transducer, Yes-associated protein (YAP1) binds to the TEA domain (TEAD1) transcription factor and controls angiogenesis. YAP1 also regulates glucose metabolism through peroxisome proliferator-activated receptor gamma co-activator 1-alpha (PGC1α), a major player controlling mitochondrial biogenesis. However, the role of YAP1-TEAD1-PGC1α signaling in mitochondrial structure, cellular metabolism, and angiogenesis in endothelial cells (ECs) remains unclear. We now find that knockdown of TEAD1 decreases the expression of PGC1α and suppresses mitochondrial biogenesis, glycolysis, and oxygen consumption in ECs. A YAP1 mutant construct, YAP1S127A, which stimulates binding of YAP1 to TEAD1, upregulates the expression of PGC1α, induces mitochondrial biogenesis, and increases oxygen consumption and glycolytic flux in ECs; in contrast, YAP1S94A, which fails to bind to TEAD1, attenuates these effects. PGC1α knockdown inhibits YAP1S127A-induced EC sprouting in vitro and vascular morphogenesis in the fibrin gel subcutaneously implanted on mice, while overexpression of PGC1α reverses vascular morphogenesis suppressed by YAP1S94A. These results suggest that YAP1-TEAD1 signaling induces mitochondrial biogenesis in ECs and stimulates angiogenesis through PGC1α. Modulation of YAP1-TEAD1-PGC1α signaling in ECs may provide a novel intervention for angiogenesis-related diseases.

Aconitine induces apoptosis in H9c2 cardiac cells via mitochondria‑mediated pathway

Aconitine, a diterpenoid alkaloids derived from Aconitum plants, is widely employed to treat various diseases. The aim of the present study was to investigate the apoptotic effect of aconitine in H9c2 cardiac cells. H9c2 cell apoptosis induced by aconitine was detected by a Cell Counting kit-8 assay, DAPI staining, Annexin V-FITC/propidium iodide double staining and western blotting. The effects of aconitine on reactive oxygen species levels and mitochondrial membrane potential were confirmed by fluorescence microscopy and flow cytometry. In addition, ATP contents were determined using a ATP-dependent bioluminescence assay kit. The levels of peroxisome proliferator activated receptor γ co-activator 1α (PGC-1α) expression and apoptosis-associated proteins including Caspase-3, B-cell lymphoma 2 (Bcl-2), Bcl-2-associated X protein (Bax) and Cytochrome c were also assessed. Taken together, the results indicated that aconitine may inhibit cell viability, decrease PGC-1α expression, induce mitochondrial dysfunctions, upregulate Cytochrome c, Bax and Caspase-3, and downregulate Bcl-2, suggesting that aconitine may induce apoptosis through mitochondria-mediated signaling pathways in H9c2 cells.

PGC-1α dictates endothelial function through regulation of eNOS expression

Endothelial dysfunction is a characteristic of many vascular related diseases such as hypertension. Peroxisome proliferator activated receptor gamma, coactivator 1α (PGC-1α) is a unique stress sensor that largely acts to promote adaptive responses. Therefore, we sought to define the role of endothelial PGC-1α in vascular function using mice with endothelial specific loss of function (PGC-1α EC KO) and endothelial specific gain of function (PGC-1α EC TG). Here we report that endothelial PGC-1α is suppressed in angiotensin-II (ATII)-induced hypertension. Deletion of endothelial PGC-1α sensitized mice to endothelial dysfunction and hypertension in response to ATII, whereas PGC-1α EC TG mice were protected. Mechanistically, PGC-1α promotes eNOS expression and activity, which is necessary for protection from ATII-induced dysfunction as mice either treated with an eNOS inhibitor (LNAME) or lacking eNOS were no longer responsive to transgenic endothelial PGC-1α expression. Finally, we determined that the orphan nuclear receptor, estrogen related receptor α (ERRα) is required to coordinate the PGC-1α -induced eNOS expression. In conclusion, endothelial PGC-1α expression protects from vascular dysfunction by promoting NO• bioactivity through ERRα induced expression of eNOS.

PGC-1α regulates the cell cycle through ATP and ROS in CH1 cells

Peroxisome proliferator-activated receptor-γ coactivator 1α (PGC-1α) is a transcriptional co-activator involved in mitochondrial biogenesis, respiratory capacity, and oxidative phosphorylation (OXPHOS). PGC-1α plays an important role in cellular metabolism and is associated with tumorigenesis, suggesting an involvement in cell cycle progression. However, the underlying mechanisms mediating its involvement in these processes remain unclear. To elucidate the signaling pathways involved in PGC-1α function, we established a cell line, CH1 PGC-1α, which stably overexpresses PGC-1α. Using this cell line, we found that over-expression of PGC-1α stimulated extra adenosine triphosphate (ATP) and reduced reactive oxygen species (ROS) production. These effects were accompanied by up-regulation of the cell cycle checkpoint regulators CyclinD1 and CyclinB1. We hypothesized that ATP and ROS function as cellular signals to regulate cyclins and control cell cycle progression. Indeed, we found that reduction of ATP levels down-regulated CyclinD1 but not CyclinB1, whereas elevation of ROS levels down-regulated CyclinB1 but not CyclinD1. Furthermore, both low ATP levels and elevated ROS levels inhibited cell growth, but PGC-1α was maintained at a constant level. Together, these results demonstrate that PGC-1α regulates cell cycle progression through modulation of CyclinD1 and CyclinB1 by ATP and ROS. These findings suggest that PGC-1α potentially coordinates energy metabolism together with the cell cycle.

Glaucoma related Proteomic Alterations in Human Retina Samples

Glaucoma related proteomic changes have been documented in cell and animal models. However, proteomic studies investigating on human retina samples are still rare. In the present work, retina samples of glaucoma and non-glaucoma control donors have been examined by a state-of-the-art mass spectrometry (MS) workflow to uncover glaucoma related proteomic changes. More than 600 proteins could be identified with high confidence (FDR < 1%) in human retina samples. Distinct proteomic changes have been observed in 10% of proteins encircling mitochondrial and nucleus species. Numerous proteins showed a significant glaucoma related level change (p < 0.05) or distinct tendency of alteration (p < 0.1). Candidates were documented to be involved in cellular development, stress and cell death. Increase of stress related proteins and decrease of new glaucoma related candidates, ADP/ATP translocase 3 (ANT3), PC4 and SRFS1-interacting protein 1 (DFS70) and methyl-CpG-binding protein 2 (MeCp2) could be documented by MS. Moreover, candidates could be validated by Accurate Inclusion Mass Screening (AIMS) and immunostaining and supported for the retinal ganglion cell layer (GCL) by laser capture microdissection (LCM) in porcine and human eye cryosections. The workflow allowed a detailed view into the human retina proteome highlighting new molecular players ANT3, DFS70 and MeCp2 associated to glaucoma.

Role of PGC-1α in Vascular Regulation: Implications for Atherosclerosis

Mitochondrial dysfunction results in high levels of oxidative stress and mitochondrial damage, leading to disruption of endothelial homeostasis. Recent discoveries have clarified several pathways, whereby mitochondrial dysregulation contributes to endothelial dysfunction and vascular disease burden. One such pathway centers around peroxisome proliferator receptor-γ coactivator 1α (PGC-1α), a transcriptional coactivator linked to mitochondrial biogenesis and antioxidant defense, among other functions. Although primarily investigated for its therapeutic potential in obesity and skeletal muscle differentiation, the ability of PGC-1α to alter a multitude of cellular functions has sparked interest in its role in the vasculature. Within this context, recent studies demonstrate that PGC-1α plays a key role in endothelial cell and smooth muscle cell regulation through effects on oxidative stress, apoptosis, inflammation, and cell proliferation. The ability of PGC-1α to affect these parameters is relevant to vascular disease progression, particularly in relation to atherosclerosis. Upregulation of PGC-1α can prevent the development of, and even encourage regression of, atherosclerotic lesions. Therefore, PGC-1α is poised to serve as a promising target in vascular disease. This review details recent findings related to PGC-1α in vascular regulation, regulation of PGC-1α itself, the role of PGC-1α in atherosclerosis, and therapies that target this key protein.

Suppression of endothelial PGC-1α is associated with hypoxia-induced endothelial dysfunction and provides a new therapeutic target in pulmonary arterial hypertension

Endothelial dysfunction plays a principal role in the pathogenesis of pulmonary arterial hypertension (PAH), which is a fatal disease with limited effective clinical treatments. Mitochondrial dysregulation and oxidative stress are involved in endothelial dysfunction. Peroxisome proliferator-activated receptor-γ coactivator-1α (PGC-1α) is a key regulator of cellular energy metabolism and a master regulator of mitochondrial biogenesis. However, the roles of PGC-1α in hypoxia-induced endothelial dysfunction are not completely understood. We hypothesized that hypoxia reduces PGC-1α expression and leads to endothelial dysfunction in hypoxia-induced PAH. We confirmed that hypoxia has a negative impact on endothelial PGC-1α in experimental PAH in vitro and in vivo. Hypoxia-induced PGC-1α inhibited the oxidative metabolism and mitochondrial function, whereas sustained PGC-1α decreased reactive oxygen species (ROS) formation, mitochondrial swelling, and NF-κB activation and increased ATP formation and endothelial nitric oxide synthase (eNOS) phosphorylation. Furthermore, hypoxia-induced changes in the mean pulmonary arterial pressure and right heart hypertrophy were nearly normal after intervention. These results suggest that PGC-1α is associated with endothelial function in hypoxia-induced PAH and that improved endothelial function is associated with improved cellular mitochondrial respiration, reduced inflammation and oxygen stress, and increased PGC-1α expression. Taken together, these findings indicate that PGC-1α may be a new therapeutic target in PAH.

MicroRNA-19b/221/222 induces endothelial cell dysfunction via suppression of PGC-1α in the progression of atherosclerosis

BACKGROUND

Peroxisome proliferator-activated receptor γ coactivator 1α (PGC-1α) is a master regulator of cellular energy metabolism that is associated with many cardiovascular diseases, including atherosclerosis. However, the role and underling regulatory mechanisms of PGC-1α in the pathogenesis of atherosclerosis are not completely understood. Here, we identified the microRNAs that post-transcriptionally regulate PGC-1α production and their roles in the pathogenesis of atherosclerosis.

METHODS AND RESULTS

A significant down-regulation of PGC-1α protein was observed in human atherosclerotic vessel samples. Using microarray and bioinformatics analyses, PGC-1α was identified as a common target gene of miR-19b-3p, miR-221-3p and miR-222-3p, which are mainly located in the intima of atherosclerotic vessels. In vitro induction of miR-19b-3p, miR-221-3p and miR-222-3p by the inflammatory cytokines TNFα and IFNγ may affect PGC-1α protein production and consequently result in mitochondrial dysfunction in Human Aortic Endothelial Cells (HAECs). The overexpression of miR-19b-3p, miR-221-3p and miR-222-3p in HAECs caused intracellular ROS accumulation, which led to cellular apoptosis.

CONCLUSION

Taken together, these results demonstrate that PGC-1α plays a protective role against the vascular complications of atherosclerosis. Moreover, the posttranscriptional regulation of PGC-1α by miR-19b/221/222 was unveiled, which provides a novel mechanism in which a panel of microRNAs can modulate endothelial cell apoptosis via the regulation mitochondrial function.

Expression of Mitochondria-Associated Genes (PPARGC1A, NRF-1, BCL-2 and BAX) in Follicular Development and Atresia of Goat Ovaries

Most follicles undergo atresia during the developmental process. Follicular atresia is predominantly regulated by apoptosis of granulosa cells, but the mechanism underlying apoptosis via the mitochondria-dependent apoptotic pathway is unclear. We aimed to investigate whether the mitochondria-associated genes peroxisome proliferator-activated receptor-gamma, coactivator1-alpha (PPARGC1A), nuclear respiratory factor-1 (NRF-1), B-cell CLL/lymphoma 2 (BCL-2) and BCL2-associated X protein (BAX) played a role in follicular atresia through this pathway. The four mitochondria-associated proteins (PGC-1α, which are encoded by the PPARGC1A gene, NRF-1, BCL-2 and BAX) mainly expressed in granulosa cells. The mRNA and protein levels of PPARGC1A/PGC-1α and NRF-1 in granulosa cells increased with the follicular development. These results showed that these genes may play a role in the regulation of the follicular development. In addition, compared with healthy follicles, the granulosa cell in atretic follicles had a reduced expression of NRF-1, increased BAX expression and increased ratio of BAX to BCL-2 expression. These results suggested that changes of the mitochondria-associated gene expression patterns in granulosa cells may lead to follicular atresia during goat follicle development.

Expression of adenine nucleotide translocase (ANT) isoform genes is controlled by PGC-1α through different transcription factors

Adenine nucleotide translocase (ANT) isoforms are mitochondrial proteins encoded by nuclear DNA that catalyze the exchange of ATP generated in the mitochondria for ADP produced in the cytosol. The aim of this study was to determine the role of the transcriptional coactivator PGC-1α (peroxisome proliferator-activated receptor-γ [PPAR-γ] coactivator 1α), a master regulator of mitochondrial oxidative metabolism, in the regulation of the expression of ANT isoform genes and to identify the transcription factors involved. We found that PGC-1α overexpression induced the expression of all ANT human and mouse isoforms but to different degrees. The transcription factor ERRα was involved in PGC-1α-induced expression of all human ANT isoforms (hANT1-3) in HeLa cells as well as in the regulation of mouse isoforms (mANT1-2) in C2C12 myotubes and 3T3-L1 adipocytes, even though ANT isoforms have important physiological differences and are regulated in a tissue-specific manner. In addition to ERRα, PPARδ and mTOR pathways were involved in the induction of mANT1-2 by PGC-1α in C2C12 myotubes, while PPARγ was involved in PGC-1α-regulation of mANT1-2 in 3T3-L1 adipocytes. Furthermore, the regulation of mANT genes by PGC-1α was also observed in vivo in knockout mouse models lacking PGC-1α. In summary, our results show that the regulation of genes encoding ANT isoforms is controlled by PGC-1α through different transcription factors depending on cell type.

PGC-1α plays a major role in the anti-apoptotic effect of 15-HETE in pulmonary artery endothelial cells

Peroxisome proliferator activated receptor gamma coactivator 1α (PGC-1α) has been confirmed as a key regulatory factor in pulmonary artery smooth muscle cells to mediate mitochondrial biogenesis and proliferation during hypoxia. However, the functional role of PGC-1α in hypoxic pulmonary artery endothelial cells (PAECs) still needs to be determined. In the present study, we found a marked elevation in the expression of PGC-1α under hypoxia, which was predominate in the nucleus of PAECs. This alteration of PGC-1α showed a significant association with 15-Hydroxyeicosatetraenoic acid (15-HETE), a regulator known to be protective against apoptosis at the concentration of 1 μM. By silencing PGC-1α, the action against cell viability suppression induced by 15-HETE was blocked, not only in normoxic condition but also in hypoxia-stimulated condition. Likewise, the tendency to reduce TUNEL-positive cells, abnormal nuclei and apoptotic cells in response to 15-HETE was depending on PGC-1α. Furthermore, 15-HETE and PGC-1α siRNA caused significant alterations in related mechanisms including caspase activity, mitochondrial membrane potential, and Bcl-2 expression. Taken together, these results provide the first evidence to confirm the importance of PGC-1α in mediating the protective effect of 15-HETE against apoptosis. Therefore, a clear role of PGC-1α in hypoxic PAECs is demonstrated, which may be attributed to pulmonary vascular remodeling.

A genome-wide association study in the genetic analysis of idiopathic thrombophilia project suggests sex-specific regulation of mitochondrial DNA levels

Identifying genes that regulate mitochondrial DNA (mtDNA) levels is of interest due to an increasing number of diseases in humans that are associated with altered mtDNA levels. We searched for nuclear polymorphisms that influence mtDNA levels using a family-based genome-wide association (GWAS) method. Also, our aim was to determine if sex influences the genetic control of mtDNA levels. Two intron-polymorphisms, in the genes PARK2 and MRPL37, showed a tendency toward an association with mtDNA levels only in females and only in males, respectively. Both genes have a role in mitochondrial biogenesis and are potential candidates for the sex-specific control of mtDNA levels.

Mitochondria, endothelial cell function, and vascular diseases

Mitochondria are perhaps the most sophisticated and dynamic responsive sensing systems in eukaryotic cells. The role of mitochondria goes beyond their capacity to create molecular fuel and includes the generation of reactive oxygen species, the regulation of calcium, and the activation of cell death. In endothelial cells, mitochondria have a profound impact on cellular function under both healthy and diseased conditions. In this review, we summarize the basic functions of mitochondria in endothelial cells and discuss the roles of mitochondria in endothelial dysfunction and vascular diseases, including atherosclerosis, diabetic vascular dysfunction, pulmonary artery hypertension, and hypertension. Finally, the potential therapeutic strategies to improve mitochondrial function in endothelial cells and vascular diseases are also discussed, with a focus on mitochondrial-targeted antioxidants and calorie restriction.

Salidroside stimulates mitochondrial biogenesis and protects against H₂O₂-induced endothelial dysfunction

Salidroside (SAL) is an active component of Rhodiola rosea with documented antioxidative properties. The purpose of this study is to explore the mechanism of the protective effect of SAL on hydrogen peroxide- (H₂O₂-) induced endothelial dysfunction. Pretreatment of the human umbilical vein endothelial cells (HUVECs) with SAL significantly reduced the cytotoxicity brought by H₂O₂. Functional studies on the rat aortas found that SAL rescued the endothelium-dependent relaxation and reduced superoxide anion (O2^∙−) production induced by H₂O₂. Meanwhile, SAL pretreatment inhibited H₂O₂-induced nitric oxide (NO) production. The underlying mechanisms involve the inhibition of H₂O₂-induced activation of endothelial nitric oxide synthase (eNOS), adenosine monophosphate-activated protein kinase (AMPK), and Akt, as well as the redox sensitive transcription factor, NF-kappa B (NF-κB). SAL also increased mitochondrial mass and upregulated the mitochondrial biogenesis factors, peroxisome proliferator-activated receptor gamma-coactivator-1alpha (PGC-1α), and mitochondrial transcription factor A (TFAM) in the endothelial cells. H₂O₂-induced mitochondrial dysfunction, as demonstrated by reduced mitochondrial membrane potential (Δψm) and ATP production, was rescued by SAL pretreatment. Taken together, these findings implicate that SAL could protect endothelium against H₂O₂-induced injury via promoting mitochondrial biogenesis and function, thus preventing the overactivation of oxidative stress-related downstream signaling pathways.

Endothelial PGC-1α mediates vascular dysfunction in diabetes

Endothelial dysfunction is a central hallmark of diabetes. The transcriptional coactivator PGC-1α is a powerful regulator of metabolism, but its role in endothelial cells remains poorly understood. We show here that endothelial PGC-1α expression is high in diabetic rodents and humans and that PGC-1α powerfully blocks endothelial migration in cell culture and vasculogenesis in vivo. Mechanistically, PGC-1α induces Notch signaling, blunts activation of Rac/Akt/eNOS signaling, and renders endothelial cells unresponsive to established angiogenic factors. Transgenic overexpression of PGC-1α in the endothelium mimics multiple diabetic phenotypes, including aberrant re-endothelialization after carotid injury, blunted wound healing, and reduced blood flow recovery after hindlimb ischemia. Conversely, deletion of endothelial PGC-1α rescues the blunted wound healing and recovery from hindlimb ischemia seen in type 1 and type 2 diabetes. Endothelial PGC-1α thus potently inhibits endothelial function and angiogenesis, and induction of endothelial PGC-1α contributes to multiple aspects of vascular dysfunction in diabetes.

S-adenosyl methionine prevents endothelial dysfunction by inducing heme oxygenase-1 in vascular endothelial cells

S-adenosyl methionine (SAM) is a key intermediate in the metabolism of sulfur amino acids and is a major methyl donor in the cell. Although the low plasma level of SAM has been associated with atherosclerosis, the effect of SAM administration on atherosclerosis is not known. Endothelial dysfunction is an early prerequisite for atherosclerosis. This study was undertaken to investigate the possible preventive effect of SAM on endothelial dysfunction and the molecular mechanism of its action. SAM treatment prevented endothelial dysfunction in high fat diet (HFD)-fed rats. In cultured human aortic endothelial cells, linoleic acid (LA) increased and SAM decreased cell apoptosis and endoplasmic reticulum stress. Both LA and SAM increased heme oxygenase-1 (HO-1) expression in an NF-E2-related factor 2-dependent manner. However, knockdown of HO-1 reversed only the SAM-induced preventive effect of cell apoptosis. The LA-induced HO-1 expression was dependent on PPARα, whereas SAM induced HO-1 in a PPAR-independent manner. These data demonstrate that SAM treatment prevents endothelial dysfunction in HFDfed animals by inducing HO-1 in vascular endothelial cells. In cultured endothelial cells, SAM-induced HO-1 was responsible for the observed prevention of cell apoptosis. We propose that SAM treatment may represent a new therapeutic strategy for atherosclerosis.

Macrophage PPAR gamma Co-activator-1 alpha participates in repressing foam cell formation and atherosclerosis in response to conjugated linoleic acid

Conjugated linoleic acid (CLA) has the unique property of inducing regression of pre-established murine atherosclerosis. Understanding the mechanism(s) involved may help identify endogenous pathways that reverse human atherosclerosis. Here, we provide evidence that CLA inhibits foam cell formation via regulation of the nuclear receptor coactivator, peroxisome proliferator-activated receptor (PPAR)-γ coactivator (PGC)-1α, and that macrophage PGC-1α plays a role in atheroprotection in vivo. PGC-1α was identified as a hub gene within a cluster in the aorta of the apoE^−/− mouse in the CLA-induced regression model. PGC-1α was localized to macrophage/foam cells in the murine aorta where its expression was increased during CLA-induced regression. PGC-1α expression was also detected in macrophages in human atherosclerosis and was inversely linked to disease progression in patients with the disease. Deletion of PGC-1α in bone marrow derived macrophages promoted, whilst over expression of the gene inhibited foam cell formation. Importantly, macrophage specific deletion of PGC-1α accelerated atherosclerosis in the LDLR^−/− mouse in vivo. These novel data support a functional role for PGC-1α in atheroprotection.

PGC-1α prevents apoptosis in adipose-derived stem cells by reducing reactive oxygen species production in a diabetic microenvironment

AIMS

To examine whether overexpression of peroxisome proliferator activated receptor-gamma coactivator-1 alpha (PGC-1α) can prevent apoptosis in adipose-derived stem cells (ASCs) by reducing reactive oxygen species (ROS) production and enhancing mitochondrial function in a diabetic environment.

METHODS

After the isolation, expansion and characterisation of rat ASCs, we overexpressed PGC-1α in ASCs using an adenoviral vector encoding green fluorescent protein (GFP) or PGC-1α and tested the apoptotic effect under conditions of high glucose, hypoxia and serum deprivation. The production of intracellular ROS and mitochondrial ROS was evaluated using dihydroethidium and CM-H2XRos fluorescent probes.

RESULTS

Under conditions of high glucose, hypoxia and serum deprivation, the overexpression of PGC-1α in ASCs decreased apoptosis and led to an increased survival rate. The ASCs modified with PGC-1α produced lower intracellular and mitochondrial ROS. The mitochondrial morphology and structure in the PGC-1α-ASC group remained relatively complete compared with the control group.

CONCLUSIONS

These results reveal a crucial protective role for PGC-1α in the treatment of diabetes mellitus and its complications using stem cells therapy.

Vaspin increases nitric oxide bioavailability through the reduction of asymmetric dimethylarginine in vascular endothelial cells

Vaspin is an adipocytokine recently identified in the visceral adipose tissue of diabetic rats and having anti-diabetic effects. We have recently shown that vaspin has anti-atherogenic effect through Akt-mediated inhibition of endothelial cell apoptosis. Decreased activity of endothelial nitric oxide synthase (eNOS) plays an important role in the pathogenesis of atherosclerosis. Asymmetric dimethylarginine (ADMA) is a well-known endogenous competitive inhibitor of eNOS and risk factor of cardiovascular diseases. The aim of this study was to examine whether vaspin might protect against atherosclerosis through its beneficial effects on the ADMA-eNOS system. Treatment of vaspin significantly increased NO secretion from endothelial cells and isolated aorta from Sprague-Dawley (SD) rats. Furthermore, treatment of vaspin prevented fatty acid-induced decrease in endothelium-dependent vasorelaxation in isolated aorta of SD rat. For the mechanism of vaspin-induced NO biosynthesis, vaspin activated the STAT3 signaling pathway and stimulated eNOS phosphorylation (Ser 1177), a marker of eNOS activation, through STAT3-dependent mechanism. Furthermore, vaspin treatment increased the expression of dimethylarginine dimethylaminohydrolase (DDAH) II, the responsible enzyme for the degradation of ADMA, leading to a reduction in ADMA levels. Vaspin-induced increase in DDAH II gene expression was through STAT3-mediated stimulation of DDAH II promoter activity. These results suggest that vaspin increases eNOS activity by reducing ADMA level through STAT3-mediated regulation of DDAH II expression. Our findings provide a novel molecular mechanism of antiatherogenic actions of vaspin.

The role of Rho/Rho-kinase pathway in the expression of ICAM-1 by linoleic acid in human aortic endothelial cells

Linoleic acid (LA), a dietary unsaturated fatty acid, has been known to increase the expression of adhesion molecules such as intercellular adhesion molecule-1 (ICAM-1) through the activation of nuclear factor-kappa B. Rho/Rho-kinase (ROCK) pathway mediates various cellular functions related to cardiovascular disease and affects the expression of ICAM-1. However, the exact mechanism underlying this action has not been fully elucidated. In this study, we aimed to find out the role of Rho/ROCK pathway in LA-induced ICAM-1 expression in human aortic endothelial cells (HAECs). We found that LA increased ICAM-1 expression and phosphorylation of ROCK and MYPT-1, a distal signal of ROCK. Y-27632, a ROCK inhibitor, suppressed ICAM-1 expression and phosphorylation of MYPT-1 induced by LA. The effect of LA on the increased phosphorylation of MYPT1 and expression of ICAM-1 was abolished by knocking down RhoA and ROCK2 protein level expression using small interfering RNA. LA increased NF-κB DNA-binding activity, which was inhibited with pretreatment with Y-27632. This study suggests that Rho/ROCK pathway plays a role in LA-induced ICAM-1 expression, which is possibly mediated by NF-κB in HAECs.

Follicular development and expression of nuclear respiratory factor-1 and peroxisome proliferator-activated receptor γ coactivator-1 alpha in ovaries of fetal and neonatal doelings

In livestock, the ovarian reserve of follicles is established during the fetal stage. However, at least two-thirds of the oocytes present in the reserve die because of apoptosis before birth. Notably, mitochondria have been reported to play a crucial role in the fate (life/death) of oocytes. In this study, mitochondrial regulators nuclear respiratory factor-1 (NRF-1) and PPAR γ coactivator-1 alpha (PGC-1α) were examined during this period of follicle development to investigate their effects on follicular development and apoptosis. Fetal and neonatal Capra haimen were used, ranging in age from 60 d postcoitum (dpc) to 30 d postpartum (dpp). Our data demonstrated that egg nests were the earliest recognizable gamete cells in ovaries of fetal and neonatal doelings. Proportions of egg nests decreased from 92.68 to 25.08% whereas single follicles increased from 7.32 to 74.92% between 60 and 120 dpc. Subsequently, between 90 and 120 dpc, the proportion of primordial follicles increased from 9.98 to 61.56% (P < 0.01). However, it did not change between 1 and 30 dpp (P = 0.12). The proportion of primary follicles increased from 1.23 to 37.93% between 90 dpc to 1 dpp (P = 0.01) but did not change between 1 and 30 dpp (P = 0.11). Meanwhile, proportions of secondary and tertiary follicles increased in an age-dependent manner. In addition, results of this study suggested that NRF-1 and PGC-1α proteins are mainly localized in germ cells of egg nests, cytoplasm of oocytes, and granulosa cells of follicles ranging from primordial to tertiary follicles. The transcript abundance of NRF-1 mRNA was up-regulated in 60-dpc-old ovaries compared with 1-dpp-old ovaries (P < 0.05), but the PGC-1α mRNA expression pattern did not change (P = 0.05). Nevertheless, the number of terminal deoxynucleotidyltransferase UTP nick-end labeling (TUNEL) positive cells and caspase-3 activity in 60-dpc-old ovaries was less than those in 1-dpp-old ovaries (P < 0.01, P = 0.01). In conclusion, our results demonstrate that the key stage of primordial follicle formation is between 90 and 120 dpc in Capra haimen. Also, this study suggests that NRF-1 and PGC-1α might have roles in cell apoptosis during ovarian development of fetal and neonatal Capra haimen. These results improve our understanding of apoptotic mechanisms in oogenesis and folliculogenesis.

Peroxisome proliferator-activated receptor-γ coactivator-1α (PGC-1α) enhances engraftment and angiogenesis of mesenchymal stem cells in diabetic hindlimb ischemia

To examine whether the peroxisome proliferator-activated receptor-γ coactivator-1α (PGC-1α), a key regulator linking angiogenesis and metabolism, could enhance the engraftment and angiogenesis of mesenchymal stem cells (MSCs) in diabetic hindlimb ischemia, we engineered the overexpression of PGC-1α within MSCs using an adenoviral vector encoding green fluorescent protein and PGC-1α, and then tested the survivability and angiogenesis of MSCs in vitro and in vivo. Under the condition of hypoxia concomitant with serum deprivation, the overexpression of PGC-1α in MSCs resulted in a higher expression level of hypoxia-inducible factor-1α (Hif-1α), a greater ratio of B-cell lymphoma leukemia-2 (Bcl-2)/Bcl-2-associated X protein (Bax), and a lower level of caspase 3 compared with the controls, followed by an increased survival rate and an elevated expression level of several proangiogenic factors. In vivo, the MSCs modified with PGC-1α could significantly increase the blood perfusion and capillary density of ischemic hindlimb of the diabetic rats, which was correlated to an improved survivability of MSCs and an increased level of several proangiogenic factors secreted by MSCs. We identified for the first time that PGC-1α could enhance the engraftment and angiogenesis of MSCs in diabetic hindlimb ischemia.

PGC-1α determines light damage susceptibility of the murine retina

The peroxisome proliferator-activated receptor γ coactivator 1 (PGC-1) proteins are key regulators of cellular bioenergetics and are accordingly expressed in tissues with a high energetic demand. For example, PGC-1α and PGC-1β control organ function of brown adipose tissue, heart, brain, liver and skeletal muscle. Surprisingly, despite their prominent role in the control of mitochondrial biogenesis and oxidative metabolism, expression and function of the PGC-1 coactivators in the retina, an organ with one of the highest energy demands per tissue weight, are completely unknown. Moreover, the molecular mechanisms that coordinate energy production with repair processes in the damaged retina remain enigmatic. In the present study, we thus investigated the expression and function of the PGC-1 coactivators in the healthy and the damaged retina. We show that PGC-1α and PGC-1β are found at high levels in different structures of the mouse retina, most prominently in the photoreceptors. Furthermore, PGC-1α knockout mice suffer from a striking deterioration in retinal morphology and function upon detrimental light exposure. Gene expression studies revealed dysregulation of all major pathways involved in retinal damage and apoptosis, repair and renewal in the PGC-1α knockouts. The light-induced increase in apoptosis in vivo in the absence of PGC-1α was substantiated in vitro, where overexpression of PGC-1α evoked strong anti-apoptotic effects. Finally, we found that retinal levels of PGC-1 expression are reduced in different mouse models for retinitis pigmentosa. We demonstrate that PGC-1α is a central coordinator of energy production and, importantly, all of the major processes involved in retinal damage and subsequent repair. Together with the observed dysregulation of PGC-1α and PGC-1β in retinitis pigmentosa mouse models, these findings thus imply that PGC-1α might be an attractive target for therapeutic approaches aimed at retinal degeneration diseases.

PGC-1 coactivators in the cardiovascular system

The beating heart consumes more ATP per weight than any other organ. The machineries required for this are many and complex. Fuel and oxygen must be transported via the vasculature, absorbed by cardiomyocytes, broken down, and regulated to match cellular demands. Much of this occurs in mitochondria, which comprise fully one third of cardiac mass. The PGC-1 proteins are transcriptional coactivators that have emerged as powerful orchestrators of these numerous processes, ensuring their proper coregulation in response to intracellular and extracellular cues. An important role for PGC-1s in cardiac function has been revealed over the past few years, and more recently interest in their role in the vasculature has been burgeoning. We review this literature, focusing on recent developments.

Time-dependent changes in lipid metabolism in mice with methionine choline deficiency-induced fatty liver disease

Methionine and choline-deficient diet (MCD)-induced fatty liver is one of the best-studied animal models of fatty liver disease. The present study was performed to clarify the relative contributions of individual lipid metabolic pathways to the pathogenesis of MCD-induced fatty liver. Hepatic lipogenesis mediated by the sterol regulatory element-binding protein (SREBP-1c) was increased at 1 week, but not at 6 weeks, of MCD feeding. On the other hand, (14)C-palmitate oxidation did not change at 1 week, but significantly decreased at 6 weeks. This decrease was associated with increased expression of fatty acid translocase, a key enzyme involved in fatty acid uptake. Expression of endoplasmic reticulum stress markers was increased in mice given MCD for both 1 and 6 weeks. These findings suggest the presence of time-dependent differences in lipid metabolism in MCD-induced fatty liver disease: SREBP-1c-mediated lipogenesis is important in the early stages of fatty liver disease, whereas increased fatty acid uptake and decreased fatty acid oxidation become more important in the later stages.

Astaxanthin induces mitochondria-mediated apoptosis in rat hepatocellular carcinoma CBRH-7919 cells

We designed to study the role of mitochondria in astaxanthin-induced apoptosis in hepatocellular carcinoma cells. Effect of astaxanthin on cell proliferation was studied by using methyl thiazolyl tetrazolium (MTT) in three tumor cell lines (CBRH-7919, SHZ-88 and Lewis) and normal human hepatocyte HL-7702 cell. Cell apoptosis rate, changes of mitochondrial morphology, mitochondrial transmembrane potential and electron transport chain were evaluated respectively. Expressions of B cell lymphoma/leukemia-2 (Bcl-2) and Bcl-2 associated X protein (Bax) were detected by Western blot. Results as following, astaxanthin had little effect on HL-7702 cell, however its inhibition was most pronounced in CBRH-7919 cell line with an IC₅₀ of 39 µM. This dose of astaxanthin and CBRH-7919 cell line were chosen for further studies. Astaxanthin could induce cell apoptosis and mitochondrial membrane damage. The mitochondrial transmembrane potential and function of electron transport chain were decreased. The expression of Bcl-2 protein was down-regulated but that of Bax protein was up-regulated. In conclusion, astaxanthin showed anticancer effect by inducing cell apoptosis through the regulation of mitochondrial-dependent manner.

PGC-1 family coactivators and cell fate: roles in cancer, neurodegeneration, cardiovascular disease and retrograde mitochondria-nucleus signalling

Over the past two decades, a complex nuclear transcriptional machinery controlling mitochondrial biogenesis and function has been described. Central to this network are the PGC-1 family coactivators, characterised as master regulators of mitochondrial biogenesis. Recent literature has identified a broader role for PGC-1 coactivators in both cell death and cellular adaptation under conditions of stress, here reviewed in the context of the pathology associated with cancer, neurodegeneration and cardiovascular disease. Moreover, we propose that these studies also imply a novel conceptual framework on the general role of mitochondrial dysfunction in disease. It is now well established that the complex nuclear transcriptional control of mitochondrial biogenesis allows for adaptation of mitochondrial mass and function to environmental conditions. On the other hand, it has also been suggested that mitochondria alter their function according to prevailing cellular energetic requirements and thus function as sensors that generate signals to adjust fundamental cellular processes through a retrograde mitochondria-nucleus signalling pathway. Therefore, altered mitochondrial function can affect cell fate not only directly by modifying cellular energy levels or redox state, but also indirectly, by altering nuclear transcriptional patterns. The current literature on such retrograde signalling in both yeast and mammalian cells is thus reviewed, with an outlook on its potential contribution to disease through the regulation of PGC-1 family coactivators. We propose that further investigation of these pathways will lead to the identification of novel pharmacological targets and treatment strategies to combat disease.

Vaspin protects vascular endothelial cells against free fatty acid-induced apoptosis through a phosphatidylinositol 3-kinase/Akt pathway

Vaspin, an adipocytokine recently identified in a rat model of type 2 diabetes, has been suggested to have an insulin-sensitizing effect. However, the exact mechanism underlying this action has not been fully elucidated. Furthermore, the specific function of vaspin is largely unknown, especially in vascular cells. We examined whether vaspin affects the insulin-signaling pathway in cultured endothelial cells and is capable of preventing free fatty acid (FFA)-induced apoptosis in endothelial cells through its insulin sensitizing effect, specifically, through its stimulatory effect on PI3-kinase/Akt signaling pathways. Vaspin significantly increased Akt phosphorylation and prevented the impairment of Akt phosphorylation by linoleic acid (LA) in insulin-stimulated endothelial cells, which effects were abolished by pretreatment with the PI3-kinase inhibitor, Wortmannin. Moreover, pretreatment with vaspin prevented LA-induced apoptosis in insulin-stimulated endothelial cells; this anti-apoptotic effect of vaspin was also eliminated by pretreatment with Wortmannin. The present study indicates that vaspin protects vascular endothelial cells from FFA-induced apoptosis through upregulation of the PI3-kinase/Akt signaling pathway. Our study is the first to demonstrate that vascular cells can be targets of vaspin. Our results further suggest that vaspin could have beneficial effects on the atherosclerosis.