FoxO3a suppresses the senescence of cardiac microvascular endothelial cells by regulating the ROS-mediated cell cycle

A nutrigeroscience approach: Dietary macronutrients and cellular senescence

Cellular senescence, a process in which a cell exits the cell cycle in response to stressors, is one of the hallmarks of aging. Senescence and the senescence-associated secretory phenotype (SASP)-a heterogeneous set of secreted factors that disrupt tissue homeostasis and promote the accumulation of senescent cells-reprogram metabolism and can lead to metabolic dysfunction. Dietary interventions have long been studied as methods to combat age-associated metabolic dysfunction, promote health, and increase lifespan. A growing body of literature suggests that senescence is responsive to diet, both to calories and specific dietary macronutrients, and that the metabolic benefits of dietary interventions may arise in part through reducing senescence. Here, we review what is currently known about dietary macronutrients' effect on senescence and the SASP, the nutrient-responsive molecular mechanisms that may mediate these effects, and the potential for these findings to inform the development of a nutrigeroscience approach to healthy aging.

Cardiovascular Disease and miRNAs: Possible Oxidative Stress-Regulating Roles of miRNAs

MicroRNAs (miRNAs) have been highlighted as key players in numerous diseases, and accumulating evidence indicates that pathological expressions of miRNAs contribute to both the development and progression of cardiovascular diseases (CVD), as well. Another important factor affecting the development and progression of CVD is reactive oxygen species (ROS), as well as the oxidative stress they may impose on the cells. Considering miRNAs are involved in virtually every biological process, it is not unreasonable to assume that miRNAs also play critical roles in the regulation of oxidative stress. This narrative review aims to provide mechanistic insights on possible oxidative stress-regulating roles of miRNAs in cardiovascular diseases based on differentially expressed miRNAs reported in various cardiovascular diseases and their empirically validated targets that have been implicated in the regulation of oxidative stress.

Circulating exosomal mir-16-2-3p is associated with coronary microvascular dysfunction in diabetes through regulating the fatty acid degradation of endothelial cells

BACKGROUND

Coronary microvascular dysfunction (CMD) is a frequent complication of diabetes mellitus (DM) characterized by challenges in both diagnosis and intervention. Circulating levels of microRNAs are increasingly recognized as potential biomarkers for cardiovascular diseases.

METHODS

Serum exosomes from patients with DM, DM with coronary microvascular dysfunction (DM-CMD) or DM with coronary artery disease (DM-CAD) were extracted for miRNA sequencing. The expression of miR-16-2-3p was assessed in high glucose-treated human aortic endothelial cells and human cardiac microvascular endothelial cells. Fluorescence in situ hybridization (FISH) was used to detect miR-16-2-3p within the myocardium of db/db mice. Intramyocardial injection of lentivirus overexpressing miR-16-2-3p was used to explore the function of the resulting gene in vivo. Bioinformatic analysis and in vitro assays were carried out to explore the downstream function and mechanism of miR-16-2-3p. Wound healing and tube formation assays were used to explore the effect of miR-16-2-3p on endothelial cell function.

RESULTS

miR-16-2-3p was upregulated in circulating exosomes from DM-CMD, high glucose-treated human cardiac microvascular endothelial cells and the hearts of db/db mice. Cardiac miR-16-2-3p overexpression improved cardiac systolic and diastolic function and coronary microvascular reperfusion. In vitro experiments revealed that miR-16-2-3p could regulate fatty acid degradation in endothelial cells, and ACADM was identified as a potential downstream target. MiR-16-2-3p increased cell migration and tube formation in microvascular endothelial cells.

CONCLUSIONS

Our findings suggest that circulating miR-16-2-3p may serve as a biomarker for individuals with DM-CMD. Additionally, miR-16-2-3p appears to alleviate coronary microvascular dysfunction in diabetes by modulating ACADM-mediated fatty acid degradation in endothelial cells.

MicroRNAs-associated with FOXO3 in cellular senescence and other stress responses

FOXO3 is a member of the FOXO transcription factor family and is known for regulating cellular survival in response to stress caused by various external and biological stimuli. FOXO3 decides cell fate by modulating cellular senescence, apoptosis and autophagy by transcriptional regulation of genes involved in DNA damage response and oxidative stress resistance. These cellular processes are tightly regulated physiologically, with FOXO3 acting as the hub that integrates signalling networks controlling them. The activity of FOXO3 is influenced by post-translational modifications, altering its subcellular localisation. In addition, FOXO3 can also be regulated directly or indirectly by microRNAs (miRNAs) or vice versa. This review discusses the involvement of various miRNAs in FOXO3-driven cellular responses such as senescence, apoptosis, autophagy, redox and inflammation defence. Given that these responses are linked and influence cell fate, a thorough understanding of the complex regulation by miRNAs would provide key information for developing therapeutic strategy and avoid unintended consequences caused by off-site targeting of FOXO3.

New Dawn for Atherosclerosis: Vascular Endothelial Cell Senescence and Death

Endothelial cells (ECs) form the inner linings of blood vessels, and are directly exposed to endogenous hazard signals and metabolites in the circulatory system. The senescence and death of ECs are not only adverse outcomes, but also causal contributors to endothelial dysfunction, an early risk marker of atherosclerosis. The pathophysiological process of EC senescence involves both structural and functional changes and has been linked to various factors, including oxidative stress, dysregulated cell cycle, hyperuricemia, vascular inflammation, and aberrant metabolite sensing and signaling. Multiple forms of EC death have been documented in atherosclerosis, including autophagic cell death, apoptosis, pyroptosis, NETosis, necroptosis, and ferroptosis. Despite this, the molecular mechanisms underlying EC senescence or death in atherogenesis are not fully understood. To provide a comprehensive update on the subject, this review examines the historic and latest findings on the molecular mechanisms and functional alterations associated with EC senescence and death in different stages of atherosclerosis.

Molecular mechanisms of endothelial dysfunction in coronary microcirculation dysfunction

Coronary microvascular endothelial cells (CMECs) react to changes in coronary blood flow and myocardial metabolites and regulate coronary blood flow by balancing vasoconstrictors-such as endothelin-1-and the vessel dilators prostaglandin, nitric oxide, and endothelium-dependent hyperpolarizing factor. Coronary microvascular endothelial cell dysfunction is caused by several cardiovascular risk factors and chronic rheumatic diseases that impact CMEC blood flow regulation, resulting in coronary microcirculation dysfunction (CMD). The mechanisms of CMEC dysfunction are not fully understood. However, the following could be important mechanisms: the overexpression and activation of nicotinamide adenine dinucleotide phosphate oxidase (Nox), and mineralocorticoid receptors; the involvement of reactive oxygen species (ROS) caused by a decreased expression of sirtuins (SIRT3/SIRT1); forkhead box O3; and a decreased SKCA/IKCA expression in the endothelium-dependent hyperpolarizing factor electrical signal pathway. In addition, p66Shc is an adapter protein that promotes oxidative stress; although there are no studies on its involvement with cardiac microvessels, it is possible it plays an important role in CMD.

Proteomic basis of mortality resilience mediated by FOXO3 longevity genotype

FOXO3 is a ubiquitous transcription factor expressed in response to cellular stress caused by nutrient deprivation, inflammatory cytokines, reactive oxygen species, radiation, hypoxia, and other factors. We showed previously that the association of inherited FOXO3 variants with longevity was the result of partial protection against mortality risk posed by aging-related life-long stressors, particularly cardiometabolic disease. We then referred to the longevity-associated genotypes as conferring "mortality resilience." Serum proteins whose levels change with aging and are associated with mortality risk may be considered as "stress proteins." They may serve as indirect measures of life-long stress. Our aims were to (1) identify stress proteins that increase with aging and are associated with an increased risk of mortality, and (2) to determine if FOXO3 longevity/resilience genotype dampens the expected increase in mortality risk they pose. A total of 4500 serum protein aptamers were quantified using the Somalogic SomaScan proteomics platform in the current study of 975 men aged 71-83 years. Stress proteins associated with mortality were identified. We then used age-adjusted multivariable Cox models to investigate the interaction of stress protein with FOXO3 longevity-associated rs12212067 genotypes. For all the analyses, the p values were corrected for multiple comparisons by false discovery rate. This led to the identification of 44 stress proteins influencing the association of FOXO3 genotype with reduced mortality. Biological pathways were identified for these proteins. Our results suggest that the FOXO3 resilience genotype functions by reducing mortality in pathways related to innate immunity, bone morphogenetic protein signaling, leukocyte migration, and growth factor response.

Mettl3-mediated m6A modification of Fgf16 restricts cardiomyocyte proliferation during heart regeneration

Cardiovascular disease is the leading cause of death worldwide due to the inability of adult heart to regenerate after injury. N6-methyladenosine (m6A) methylation catalyzed by the enzyme methyltransferase-like 3 (Mettl3) plays an important role in various physiological and pathological bioprocesses. However, the role of m6A in heart regeneration remains largely unclear. To study m6A function in heart regeneration, we modulated Mettl3 expression in vitro and in vivo. Knockdown of Mettl3 significantly increased the proliferation of cardiomyocytes and accelerated heart regeneration following heart injury in neonatal and adult mice. However, Mettl3 overexpression decreased cardiomyocyte proliferation and suppressed heart regeneration in postnatal mice. Conjoint analysis of methylated RNA immunoprecipitation sequencing (MeRIP-seq) and RNA-seq identified Fgf16 as a downstream target of Mettl3-mediated m6A modification during postnatal heart regeneration. RIP-qPCR and luciferase reporter assays revealed that Mettl3 negatively regulates Fgf16 mRNA expression in an m6A-Ythdf2-dependent manner. The silencing of Fgf16 suppressed the proliferation of cardiomyocytes. However, the overexpression of ΔFgf16, in which the m6A consensus sequence was mutated, significantly increased cardiomyocyte proliferation and accelerated heart regeneration in postnatal mice compared with wild-type Fgf16. Our data demonstrate that Mettl3 post-transcriptionally reduces Fgf16 mRNA levels through an m6A-Ythdf2-dependen pathway, thereby controlling cardiomyocyte proliferation and heart regeneration.

FoxO3 restricts liver regeneration by suppressing the proliferation of hepatocytes

Upon injury, the liver is capable of substantial regeneration from the original tissue until an appropriate functional size. The underlying mechanisms controlling the liver regeneration processes are not well elucidated. Previous studies have proposed that the transcription factor FoxO3 is involved in various liver diseases, but its exact role in the regulation of liver regeneration remains largely unclear. To directly test the detailed role of FoxO3 in liver regeneration, both a constitutive Albumin-Cre driver line and adeno-associated virus serotype 8 (AAV8)-Tbg-Cre (AAV-Cre)-injected adult FoxO3^fl/fl mice were subjected to 70% partial hepatectomy (PH). Our data demonstrate that FoxO3 deletion accelerates liver regeneration primarily by limiting polyploidization and promoting the proliferation of hepatocytes during liver regeneration. RNA-seq analysis indicates that FoxO3 deficiency greatly alters the expression of gene sets associated with cell proliferation and apoptosis during liver regeneration. Chromatin immunoprecipitation-PCR (ChIP-PCR) and luciferase reporter assays reveal that FoxO3 promotes the expression of Nox4 but suppresses the expression of Nr4a1 in hepatocytes. AAV8 virus-mediated overexpression of Nox4 and knockdown of Nr4a1 significantly suppressed hepatocyte proliferation and liver regeneration in FoxO3-deficient mice. We demonstrate that FoxO3 negatively controls hepatocyte proliferation through Nox4 upregulation and Nr4a1 downregulation, thereby ensuring appropriate functional regeneration of the liver. Our findings provide novel mechanistic insight into the therapeutic mechanisms of FoxO3 in liver damage and repair.

Senolysis induced by 25-hydroxycholesterol targets CRYAB in multiple cell types

Cellular senescence is a driver of many age-related pathologies. There is an active search for pharmaceuticals termed senolytics that can mitigate or remove senescent cells in vivo by targeting genes that promote the survival of senescent cells. We utilized single-cell RNA sequencing to identify CRYAB as a robust senescence-induced gene and potential target for senolysis. Using chemical inhibitor screening for CRYAB disruption, we identified 25-hydroxycholesterol (25HC), an endogenous metabolite of cholesterol biosynthesis, as a potent senolytic. We then validated 25HC as a senolytic in mouse and human cells in culture and in vivo in mouse skeletal muscle. Thus, 25HC represents a potential class of senolytics, which may be useful in combating diseases or physiologies in which cellular senescence is a key driver.

Longevity Factor FOXO3: A Key Regulator in Aging-Related Vascular Diseases

Forkhead box O3 (FOXO3) has been proposed as a homeostasis regulator, capable of integrating multiple upstream signaling pathways that are sensitive to environmental changes and counteracting their adverse effects due to external changes, such as oxidative stress, metabolic stress and growth factor deprivation. FOXO3 polymorphisms are associated with extreme human longevity. Intriguingly, longevity-associated single nucleotide polymorphisms (SNPs) in human FOXO3 correlate with lower-than-average morbidity from cardiovascular diseases in long-lived people. Emerging evidence indicates that FOXO3 plays a critical role in vascular aging. FOXO3 inactivation is implicated in several aging-related vascular diseases. In experimental studies, FOXO3-engineered human ESC-derived vascular cells improve vascular homeostasis and delay vascular aging. The purpose of this review is to explore how FOXO3 regulates vascular aging and its crucial role in aging-related vascular diseases.

Research progress on the molecular mechanism of coronary microvascular endothelial cell dysfunction

Coronary microvascular disease is a high-risk factor for many cardiovascular events. However, due to its high concealment and many etiologies, the current understanding of its pathophysiological mechanism is very limited, which greatly limits its clinical diagnosis and treatment. In the process of the occurrence and development of coronary microvascular disease, the damage of coronary microvascular endothelial cell (CMEC) is the core link. CMEC's stress, metabolism, inflammation and other dysfunctions have a causal relationship with coronary microvascular disease, and are also the main features of coronary microvascular disease in the early stage. This article mainly reviews the molecular mechanisms of CMEC damage.

The role of molecular mechanism of Ten-Eleven Translocation2 (TET2) family proteins in pathogenesis of cardiovascular diseases (CVDs)

Cardiovascular disease (CVD) is one of the most common diseases worldwide. The underlying pathogenesis of the disease has not yet been determined, but many factors have been identified. Tet methylcytosine dioxygenase 2 (TET2) is one of the epigenetic factors involved in regulating many genes. Therefore, based on the studies shown, this factor plays an important role in preventing the occurrence of CVD. TET2 has been shown to increase angiogenesis by expressing Robo4. It also increases the activity of Matrix metalloproteinases (MMPs) and stimulates the secretion of Vascular endothelial growth factor angiogenesis. On the other hand, it has been shown that TET2 regulates the expression of several genes and the development of the heart during the embryonic period due to its oxygenating role. TET2 has been shown to regulates the expression of the genes such as Ying Yang1 (YY1), Sox9b, Inhbaa and many other genes that ultimately lead to the differentiation of cardiomyocytes. On the other hand, it has been shown that some Long non coding RNA and MicroRNAs reduce TET2 expression and CVD. Finally, it is concluded that inducing TET2 expression can be a good therapeutic strategy to prevent or improve CVD.

Current perspective on the regulation of FOXO4 and its role in disease progression

Forkhead box O4 (FOXO4) is a member of the FOXO family that regulates a number of genes involved in metabolism, cell cycle, apoptosis, and cellular homeostasis via transcriptional activity. It also mediates cell responses to oxidative stress and treatment with antitumor agents. The expression of FOXO4 is repressed by microRNAs in multiple cancer cells, while FOXO4 function is regulated by post-translational modifications and interaction with other proteins. The deregulation of FOXO4 is closely linked to the progression of several types of cancer, senescence, and other diseases. In this review, we present recent findings on the regulation of FOXO4 in physiological and pathological conditions and provide an overview of the complex role of FOXO4 in disease development and response to therapy.

Natural Polyphenols Targeting Senescence: A Novel Prevention and Therapy Strategy for Cancer

Cancer is one of the most serious diseases endangering human health. In view of the side effects caused by chemotherapy and radiotherapy, it is necessary to develop low-toxic anti-cancer compounds. Polyphenols are natural compounds with anti-cancer properties and their application is a considerable choice. Pro-senescence therapy is a recently proposed anti-cancer strategy and has been shown to effectively inhibit cancer. It is of great significance to clarify the mechanisms of polyphenols on tumor suppression by inducing senescence. In this review, we delineated the characteristics of senescent cells, and summarized the mechanisms of polyphenols targeting tumor microenvironment and inducing cancer cell senescence for cancer prevention and therapy. Although many studies have shown that polyphenols effectively inhibit cancer by targeting senescence, it warrants further investigation in preclinical and clinical studies.

FoxO3a depletion accelerates cutaneous wound healing by regulating epithelial‑mesenchymal transition through β‑catenin activation

The hysteresis of keratinocyte (KC) re-epithelialization is an important factor resulting in chronic wounds; however, the molecular mechanisms involved in this cellular response remain yet to be completely elucidated. The present study demonstrated the function of transcription factor Forkhead box O3a (FoxO3a) in KC growth and migration functional effects, resulting in restrained KC re-epithelialization during wound healing. In chronic wound tissue samples, the expression of FoxO3a was significantly increased when compared with the acute wound healing group (P<0.01). Overexpressing FoxO3a significantly inhibited, whereas silencing endogenous FoxO3a enhanced, the growth and migration of HaCaT cells in vitro. Further investigation revealed that FoxO3a negatively regulated matrix metalloproteinases 1 and 9, and increased the expression of tissue inhibitor of metalloproteinase 1. In addition, the upregulation of FoxO3a retarded, whereas the downregulation of FoxO3a accelerated, transforming growth factor-β1-induced epithelial-mesenchymal transition in HaCaT cells. Mechanistically, the overexpression of FoxO3a inactivated β-catenin signaling and markedly reduced the levels of nuclear β-catenin. These results reveal a novel mechanism of FoxO3a in regulating KC re-epithelialization, and provide novel targets for the prevention and treatment of chronic wounds.

LongShengZhi capsule inhibits doxorubicin-induced heart failure by anti-oxidative stress

Heart failure is a major cause of morbidity and mortality worldwide. LongShengZhi capsule (LSZ), a traditional Chinese medicine, is used for treatment of patients with vascular diseases. Herein we investigated the effect of LSZ treatment on doxorubicin (DOX)-induced heart failure in mice. C57BL/6 mice randomly in 3 groups received following treatment: Control group, mice were fed normal chow; DOX group, mice were intraperitoneally injected DOX to induce heart failure and fed normal chow; and LSZ group, mice were injected DOX and fed normal chow containing LSZ. DOX induced heart failure as evidenced by increased serum creatine kinase, lactic dehydrogenase and α-hydroxybutyrate dehydrogenase, and cardiac fibrosis. However, LSZ treatment substantially inhibited DOX-induced heart failure parameters. Mechanistically, LSZ reduced collagen content and fibrosis by inhibiting expression of collagen type I α1 (COL1α1), COL1α2, α-smooth muscle actin and transforming growth factor β1. In addition, DOX-induced cell apoptosis was inhibited by LSZ, coupled with reduced caspase 3 activity and mRNA expression. LSZ decreased inflammatory cytokine levels. More importantly, LSZ decreased oxidative stress by inducing expression of anti-oxidative stress enzymes including superoxide dismutase 1 (SOD1), SOD2, catalase and glutathione peroxidase 1 through activation of forkhead box O3A and sirtuin 3. In conclusion, our study demonstrates that LSZ reduces heart failure by reducing production of reactive oxygen species and inhibiting inflammation/apoptosis. Our study also suggests the potential application of LSZ for heart failure treatment.

Forkhead box O3 protects the heart against paraquat-induced aging-associated phenotypes by upregulating the expression of antioxidant enzymes

Paraquat (PQ) promotes cell senescence in brain tissue, which contributes to Parkinson's disease. Furthermore, PQ induces heart failure and oxidative damage, but it remains unknown whether and how PQ induces cardiac aging. Here, we demonstrate that PQ induces phenotypes associated with senescence of cardiomyocyte cell lines and results in cardiac aging‐associated phenotypes including cardiac remodeling and dysfunction in vivo. Moreover, PQ inhibits the activation of Forkhead box O3 (FoxO3), an important longevity factor, both in vitro and in vivo. We found that PQ‐induced senescence phenotypes, including proliferation inhibition, apoptosis, senescence‐associated β‐galactosidase activity, and p16^INK4a expression, were significantly enhanced by FoxO3 deficiency in cardiomyocytes. Notably, PQ‐induced cardiac remolding, apoptosis, oxidative damage, and p16^INK4a expression in hearts were exacerbated by FoxO3 deficiency. In addition, both in vitro deficiency and in vivo deficiency of FoxO3 greatly suppressed the activation of antioxidant enzymes including catalase (CAT) and superoxide dismutase 2 (SOD2) in the presence of PQ, which was accompanied by attenuation in cardiac function. The direct in vivo binding of FoxO3 to the promoters of the Cat and Sod2 genes in the heart was verified by chromatin immunoprecipitation (ChIP). Functionally, overexpression of Cat or Sod2 alleviated the PQ‐induced senescence phenotypes in FoxO3‐deficient cardiomyocyte cell lines. Overexpression of FoxO3 and CAT in hearts greatly suppressed the PQ‐induced heart injury and phenotypes associated with aging. Collectively, these results suggest that FoxO3 protects the heart against an aging‐associated decline in cardiac function in mice exposed to PQ, at least in part by upregulating the expression of antioxidant enzymes and suppressing oxidative stress.

Lipopolysaccharide induced the proliferation of mouse lung fibroblasts by suppressing FoxO3a/p27 pathway

Aberrant aggregation and activation of lung fibroblasts is a key process in pulmonary fibrosis, but the underlying mechanism remains enigmatic. Forkhead Box O3a (FoxO3a) is considered to be an important transcription factor that could regulate both cell cycle and cell viability. To investigate the role of FoxO3a on LPS-induced lung fibroblast proliferation, we transfected FoxO3a-SiRNA or FoxO3a-OE lentivirus into cultured mouse lung fibroblasts to knockdown or overexpress FoxO3a and pretreated mouse lung fibroblasts with gefitinib to enhance FoxO3a activity. The proliferation of lung fibroblasts was evaluated by CCK8 assay, the expression of FoxO3a, phosphorylated FoxO3a (p-FoxO3a) and p27 were measured by Western blot. We found that the proliferation of mouse lung fibroblasts mediated by LPS is accompanied by the inactivation of FoxO3a. The knockdown of FoxO3a could further decreased the expression of p27 mediated by LPS, while the overexpression of FoxO3a significantly increased the expression of p27 and suppressed LPS-induced lung fibroblast proliferation. Upon treating fibroblasts with gefitinib, the phosphorylation of FoxO3a was reduced and FoxO3a translocated into the nucleus, the expression of p27 was significantly increased and the proliferation of lung fibroblasts mediated by LPS could also be inhibited effectively. The results indicate that overexpression and reduced phosphatase activity of FoxO3a inhibit LPS-induced lung fibroblast proliferation through the activation of FoxO3a/p27 signaling pathways. Thus, to enhance FoxO3a activity could be a potential therapeutic target for LPS-induced pulmonary fibrosis.

Regulation of cellular senescence via the FOXO4-p53 axis

Forkhead box O (FOXO) and p53 proteins are transcription factors that regulate diverse signalling pathways to control cell cycle, apoptosis and metabolism. In the last decade both FOXO and p53 have been identified as key players in aging, and their misregulation is linked to numerous diseases including cancers. However, many of the underlying molecular mechanisms remain mysterious, including regulation of ageing by FOXOs and p53. Several activities appear to be shared between FOXOs and p53, including their central role in the regulation of cellular senescence. In this review, we will focus on the recent advances on the link between FOXOs and p53, with a particular focus on the FOXO4‐p53 axis and the role of FOXO4/p53 in cellular senescence. Moreover, we discuss potential strategies for targeting the FOXO4‐p53 interaction to modulate cellular senescence as a drug target in treatment of aging‐related diseases and morbidity.

Schistosome-Induced Fibrotic Disease: The Role of Hepatic Stellate Cells

Hepatic fibrosis is a common pathology in various liver diseases. Hepatic stellate cells (HSCs) are the main cell type responsible for collagen deposition and fibrosis formation in the liver. Schistosomiasis is characterised by granulomatous fibrosis around parasite eggs trapped within the liver and other host tissues. This response is facilitated by the recruitment of immune cells and the activation of HSCs. The interactions between HSCs and schistosome eggs are complex and diverse, and a better understanding of these interactions could lead to improved resolution of fibrotic liver disease, including that associated with schistosomiasis. Here, we discuss recent advances in HSC biology and the role of HSCs in hepatic schistosomiasis.

FoxO transcription factors in cancer metabolism

FoxO transcription factors serve as the central regulator of cellular homeostasis and are tumor suppressors in human cancers. Recent studies have revealed that, besides their classic functions in promoting cell death and inducing cell cycle arrest, FoxOs also regulate cancer metabolism, an emerging hallmark of cancer. In this review, we summarize the regulatory mechanisms employed to control FoxO activities in the context of cancer biology, and discuss FoxO function in metabolism reprogramming in cancer and interaction with other key cancer metabolism pathways. A deeper understanding of FoxOs in cancer metabolism may reveal novel therapeutic opportunities in cancer treatment.

CpG oligodeoxynucleotide preconditioning improves cardiac function after myocardial infarction via modulation of energy metabolism and angiogenesis

Unmethylated CpG oligodeoxynucleotide (CpG-ODN), a Toll-like receptor 9 (TLR9) ligand, has been shown to protect against myocardial ischemia/reperfusion injury. However, the potential effects of CpG-ODN on myocardial infarction (MI) induced by persistent ischemia remains unclear. Here, we investigated whether and how CpG-ODN preconditioning protects against MI in mice. C57BL/6 mice were treated with CpG-ODN by i.p. injection 2 hr prior to MI induction, and cardiac function, and histology were analyzed 2 weeks after MI. Both 1826-CpG and KSK-CpG preconditioning significantly improved the left ventricular (LV) ejection fraction (LVEF) and LV fractional shortening (LVFS) when compared with non-CpG controls. Histological analysis further confirmed the cardioprotection of CpG-ODN preconditioning. In vitro studies further demonstrated that CpG-ODN preconditioning increases cardiomyocyte survival under hypoxic/ischemic conditions by enhancing stress tolerance through TLR9-mediated inhibition of the SERCA2/ATP and activation of AMPK pathways. Moreover, CpG-ODN preconditioning significantly increased angiogenesis in the infarcted myocardium compared with non-CpG. However, persistent TLR9 activation mediated by lentiviral infection failed to improve cardiac function after MI. Although CpG-ODN preconditioning increased angiogenesis in vitro, both the persistent stimulation of CpG-ODN and stable overexpression of TLR9 suppressed the tube formation of cardiac microvascular endothelial cells. CpG-ODN preconditioning significantly protects cardiac function against MI by suppressing the energy metabolism of cardiomyocytes and promoting angiogenesis. Our data also indicate that CpG-ODN preconditioning may be useful in MI therapy.

Gene delivery of hypoxia-inducible VEGF targeting collagen effectively improves cardiac function after myocardial infarction

Vascular endothelial growth factor (VEGF) plays important roles in improvement of cardiac function following myocardial infarction (MI). However, the lack of a steerable delivery system of VEGF targeting the infarcted myocardium reduces the therapeutic efficacy and safety. Here, we constructed a series of lentiviral vector systems which could express a fusion protein consisted of a collagen-binding domain (CBD) and hVEGF (CBDhVEGF), under the control of 5HRE-hCMVmp (5HRE), the hypoxia-inducible promoter consists of five copies of the hypoxia-responsive element (HRE) and a human cytomegalovirus minimal promoter (hCMVmp). We demonstrated that 5HRE has the comparable ability to strongly drive CBDhVEGF under hypoxic condition as the ubiquitous CMV promoter, but it can hardly drive target gene under normoxic condition. 5HRE-drived CBDhVEGF specifically bound to type I collagen and significantly promoted the viability of HUVEC cells. Moreover, after injection of lentivirus into heart of mouse with MI, CBDhVEGF was mainly retained in infarcted myocardium where containing rich collagen and significantly improved angiogenesis and cardiac function when compared with hVEGF. Moreover, CBDhVEGF mediated by lentivirus has little leakage from infarcted zone into blood than hVEGF. Taken together, our results indicate that 5HRE-CBDhVEGF lentiviral vector system could improve cardiac function in the collagen-targeting and hypoxia-inducible manners.

Piper betle L. Modulates Senescence-Associated Genes Expression in Replicative Senescent Human Diploid Fibroblasts

Piper betle (PB) is a traditional medicine that is widely used to treat different diseases around Asian region. The leaf extracts contain various bioactive compounds, which were reported to have antidiabetic, antibacterial, anti-inflammatory, antioxidant, and anticancer effects. In this study, the effect of PB aqueous extracts on replicative senescent human diploid fibroblasts (HDFs) was investigated by determining the expressions of senescence-associated genes using quantitative PCR. Our results showed that PB extracts at 0.4 mg/ml can improve cell proliferation of young (143%), presenescent (127.3%), and senescent (157.3%) HDFs. Increased expressions of PRDX6, TP53, CDKN2A, PAK2, and MAPK14 were observed in senescent HDFs compared to young and/or presenescent HDFs. Treatment with PB extracts modulates the transcriptional profile changes in senescent HDFs. By contrast, expressions of SOD1 increased, whereas GPX1, PRDX6, TP53, CDKN2A, PAK2, and MAPK14 were decreased in PB-treated senescent HDFs compared to untreated senescent HDFs. In conclusion, this study indicates the modulation of PB extracts on senescence-associated genes expression of replicative senescent HDFs. Further studies warrant determining the mechanism of PB in modulating replicative senescence of HDFs through these signaling pathways.

Soluble Egg Antigens of Schistosoma japonicum Induce Senescence of Activated Hepatic Stellate Cells by Activation of the FoxO3a/SKP2/P27 Pathway

BACKGROUND

Liver fibrosis was viewed as a reversible process. The activation of hepatic stellate cells (HSCs) is a key event in the process of liver fibrosis. The induction of senescence of HSCs would accelerate the clearance of the activated HSCs. Previously, we demonstrated that soluble egg antigens (SEA) of Schistosoma japonicum promoted the senescence of HSCs via STAT3/P53/P21 pathway. In this paper, our study was aimed to explore whether there are other signaling pathways in the process of SEA-induced HSCs aging and the underlying effect of SKP2/P27 signal on senescent HSCs.

METHODOLOGY/PRINCIPAL FINDINGS

Human hepatic stellate cell line, LX-2 cells, were cultured and stimulated with SEA. Western blot and cellular immunofluorescence analysis were performed to determine the expression of senescence-associated protein, such as P27, SKP2 and FoxO3a. Besides, RNA interfering was applied to knockdown the expression of related protein. The senescence of HSCs was determined by senescence-associated β-gal staining. We found that SEA increased the expression of P27 protein, whereas it inhibited the expression of SKP2 and FoxO3a. Knockdown of P27 as well as overexpression of SKP2 both suppressed the SEA-induced senescence of HSCs. In addition, the nuclear translocation of FoxO3a from the nucleus to the cytoplasm was induced by SEA stimulation.

CONCLUSIONS/SIGNIFICANCE

The present study demonstrates that SEA promotes HSCs senescence through the FoxO3a/SKP2/P27 pathway.

Melatonin improves age-induced fertility decline and attenuates ovarian mitochondrial oxidative stress in mice

Increasing evidence shows that melatonin protected against age-related mitochondrial oxidative damage. However, the protective effects of melatonin against ovarian aging has not been explored. Young Kunming females (aged 2–3 months) were fed with melatonin added to drinking water for 6 or 12 months (mo). We found that long-term (12 mo) melatonin treatment significantly reduced ovarian aging, as indicated by substantial increases in litter size, pool of follicles, and telomere length as well as oocyte quantity and quality. Melatonin treatment suppressed ovarian mitochondrial oxidative damage by decreasing mitochondrial reactive oxygen species (mROS) generation, inhibiting apoptosis, repressing collapse of mitochondrial membrane potential and preserving respiratory chain complex activities. Female mice fed with melatonin had enhanced mitochondrial antioxidant activities, thus reducing the risk of mitochondrial oxidative damage cause by free radicals. Notably, melatonin treatment enhanced SIRT3 activity but not the protein expression level, and increased the binding affinity of FoxO3a to the promoters of both superoxide dismutase 2 (SOD2) and catalase (CAT). In conclusion, melatonin exerted protection against aging-induced fertility decline and maintenance of mitochondrial redox balance.

Hypoxia/ischemia promotes CXCL10 expression in cardiac microvascular endothelial cells by NFkB activation

CXCL10, the chemokine with potent chemotactic activity on immune cells and other non-immune cells expressing its receptor CXCR3, has been demonstrated to involve in myocardial infarction, which was resulted from hypoxia/ischemia. The cardiac microvascular endothelial cells (CMECs) are the first cell type which is implicated by hypoxia/ischemia. However, the potential molecular mechanism by which hypoxia/ischemia regulates the expression of CXCL10 in CMECs remains unclear. In the present study, the expression of CXCL10 was firstly examined by real-time PCR and ELISA analysis. Several potential binding sites (BS) for transcription factors including NF-kappaB (NFkB), HIF1 alpha (HIF1α) and FoxO3a were identified in the promoter region of CXCL10 gene from -2000 bp to -1 bp using bioinformatics software. Luciferase reporter gene vectors for CXCL10 promoter and for activation of above transcription factors were constructed. The activation of NFkB, hypoxia-inducible transcription factor-1 alpha (HIF-1α) and FoxO3a was also analyzed by Western blotting. It was shown that the production of CXCL10 in CMECs was significantly increased by hypoxia/ischemia treatment, in parallel with the activation of CXCL10 promoter examined by reporter gene vector system. Furthermore, transcription factors including NFkB, HIF1α and FoxO3a were activated by hypoxia/ischemia in CMECs. However, over-expression of NFkB, but not that of HIF1α or FoxO3a, significantly promoted the activation of CXCL10 promoter reporter gene. These findings indicated that CXCL10 production in CMECs was significantly increased by hypoxia/ischemia, at least in part, through activation of NFkB pathway and subsequently binding to CXCL10 promoter, finally promoted the transcription of CXCL10 gene.