Forkhead transcription factors and cardiovascular biology

Cell Fate Regulation During the Development of Infantile Hemangioma

As the most common benign vascular tumor in infants, infantile hemangioma (IH) is characterized by rapid growth and vasculogenesis early in infancy, followed by spontaneous involution into fibrofatty tissues over time. Extensive evidence suggests that IH originates from hemangioma stem cells (HemSCs), a group of stem cells with clonal expansion and multi-directional differentiation capacity. However, the intricate mechanisms governing the cell fate transition of HemSCs during IH development remain elusive. Here we comprehensively examine the cellular composition of IH, emphasizing the nuanced properties of various IH cell types and their correlation with the clinical features of the tumor. We also summarize the current understanding of the regulatory pathways directing HemSC differentiation into endothelial cells (ECs), pericytes, and adipocytes throughout the stages of IH progression and involution. Furthermore, we discuss recent advances in unraveling the transcriptional and epigenetic regulation of EC and adipocyte development under physiological conditions, which offer crucial perspectives for understanding IH pathogenesis.

Euphorbiasteroid induces neurotoxicity through the FOXO/NF-κB/apoptosis signaling pathway

BACKGROUND

Euphorbiasteroid, a bioactive compound from Euphorbia lathyris L., exhibits significant pharmacological effects, including anti-tumor activity and multi-drug resistance reversal. However, its potential neurotoxicity limits its clinical use. This study investigates the neurotoxic effects of euphorbiasteroid and elucidates the underlying mechanisms.

METHODS

Neurotoxicity was evaluated in differentiated PC12 cells and primary astrocytes through cell viability and lactate dehydrogenase (LDH) assays. Transcriptomic analysis was employed to predict the involvement of the Forkhead box O (FOXO), nuclear factor-kappa B (NF-κB), and apoptosis pathways in euphorbiasteroid-induced cytotoxicity. Apoptosis was detected using TdT-mediated dUTP Nick-End Labeling (TUNEL) staining, and western blot analysis of quantified apoptotic markers and key signaling proteins. Molecular docking studies explored the interaction between euphorbiasteroid and FOXO3A, while gene knockdown experiments assessed the role of FOXO3A.

RESULTS

Euphorbiasteroid significantly induced cytotoxicity in differentiated PC12 cells and primary astrocytes, linked to the activation of the FOXO, NF-κB, and apoptosis pathways. Apoptosis was confirmed by TUNEL staining, Bax/Bcl-2 ratio, and cleaved caspase 3 levels. Additionally, euphorbiasteroid reduced phospho-FOXO3A levels, promoted FOXO3A nuclear translocation and enhanced NF-κBp65 phosphorylation. Molecular docking revealed direct binding of euphorbiasteroid to FOXO3A, and FOXO3A knockdown substantially mitigated its neurotoxicity.

CONCLUSION

Euphorbiasteroid induces neurotoxicity through the activation of the FOXO/NF-κB/apoptosis signaling pathway. These findings provide new insights into the mechanisms of euphorbiasteroid-induced neurotoxicity and suggest potential strategies to mitigate these effects, which is crucial for its therapeutic application.

Transcription factor ZEB1 coordinating with NuRD complex to promote oncogenesis through glycolysis in colorectal cancer

Background

Colorectal cancer (CRC) is an aggressive primary intestinal malignancy with the third-highest incidence and second-highest mortality among all cancer types worldwide. Transcription factors (TFs) regulate cell development and differentiation owing to their ability to recognize specific DNA sequences upstream of genes. Numerous studies have demonstrated a strong correlation between TFs, the etiology of tumors, and therapeutic approaches. Here, we aimed to explore prognosis-related TFs and comprehend their carcinogenic mechanisms, thereby offering novel insights into the diagnosis and management of CRC.

Materials and Methods

Differentially expressed TFs between CRC and normal tissues were identified leveraging The Cancer Genome Atlas database, Weighted correlation network analysis and Cox regression analysis were performed to identify prognosis-related TFs. The cellular functions of hub TF zinc finger E-box binding homeobox 1 (ZEB1) were determined using by 5-ethynyl-2'-deoxyuridine and cell invasion assays in CRC cells. RNA-sequencing, Kyoto Encyclopedia of Genes and Genomes enrichment, and gene set enrichment analyses were used to identify the cellular processes in which ZEB1 participates. Immunoaffinity purification, silver staining mass spectrometry, and a chromatin immunoprecipitation assay were conducted to search for proteins that might interact with ZEB1 and the target genes they jointly regulate.

Results

Thirteen central TFs related to prognosis were identified through bioinformatics analysis techniques. Among these TFs, ZEB1 emerged as the TF most closely associated with CRC, as determined through a combination of regulatory network diagrams, survival curves, and phenotype analyses. ZEB1 promotes CRC cell growth by recruiting the NuRD(MTA1) complex, and the ZEB1/NuRD(MTA1) complex transcriptionally represses glycolysis-associated tumor suppressor genes.

Conclusion

Our study not only identified a hub biomarker related to CRC prognosis but also revealed the specific molecular mechanisms through which ZEB1 affects cancer progression. These insights provide crucial evidence for the diagnosis of CRC and potential treatment opportunities.

Thrombomodulin: a multifunctional receptor modulating the endothelial quiescence

Thrombomodulin (TM) is a type 1 receptor best known for its function as an anticoagulant cofactor for thrombin activation of protein C on the surface of vascular endothelial cells. In addition to its anticoagulant cofactor function, TM also regulates fibrinolysis, complement, and inflammatory pathways. TM is a multidomain receptor protein with a lectin-like domain at its N-terminus that has been shown to exhibit direct anti-inflammatory functions. This domain is followed by 6 epidermal growth factor-like domains that support the interaction of TM with thrombin. The interaction inhibits the procoagulant function of thrombin and enables the protease to regulate the anticoagulant and fibrinolytic pathways by activating protein C and thrombin-activatable fibrinolysis inhibitor. TM has a Thr/Ser-rich region immediately above the membrane surface that harbors chondroitin sulfate glycosaminoglycans, and this region is followed by a single-spanning transmembrane and a C-terminal cytoplasmic domain. The structure and physiological function of the extracellular domains of TM have been extensively studied, and numerous excellent review articles have been published. However, the physiological function of the cytoplasmic domain of TM has remained poorly understood. Recent data from our laboratory suggest that intracellular signaling by the cytoplasmic domain of TM plays key roles in maintaining quiescence by modulating phosphatase and tensin homolog signaling in endothelial cells. This article briefly reviews the structure and function of extracellular domains of TM and focuses on the mechanism and possible physiological importance of the cytoplasmic domain of TM in modulating phosphatase and tensin homolog signaling in endothelial cells.

Exploring the Gut-Mitochondrial Axis: p66Shc Adapter Protein and Its Implications for Metabolic Disorders

This review investigates the multifaceted role of the p66Shc adaptor protein and the gut microbiota in regulating mitochondrial function and oxidative stress, and their collective impact on the pathogenesis of chronic diseases. The study delves into the molecular mechanisms by which p66Shc influences cellular stress responses through Rac1 activation, Forkhead-type transcription factors inactivation, and mitochondria-mediated apoptosis, alongside modulatory effects of gut microbiota-derived metabolites and endotoxins. Employing an integrative approach, the review synthesizes findings from a broad array of studies, including molecular biology techniques and analyses of microbial metabolites' impacts on host cellular pathways. The results underscore a complex interplay between microbial metabolites, p66Shc activation, and mitochondrial dysfunction, highlighting the significance of the gut microbiome in influencing disease outcomes through oxidative stress pathways. Conclusively, the review posits that targeting the gut microbiota-p66Shc-mitochondrial axis could offer novel therapeutic strategies for mitigating the development and progression of metabolic diseases. This underscores the potential of dietary interventions and microbiota modulation in managing oxidative stress and inflammation, pivotal factors in chronic disease etiology.

FOXO1 stimulates tip cell-enriched gene expression in endothelial cells

Forkhead box O (FOXO) family proteins are expressed in various cells, and play crucial roles in cellular metabolism, apoptosis, and aging. FOXO1-null mice exhibit embryonic lethality due to impaired endothelial cell (EC) maturation and vascular remodeling. However, FOXO1-mediated genome-wide regulation in ECs remains unclear. Here, we demonstrate that VEGF dynamically regulates FOXO1 cytosol-nucleus translocation. FOXO1 re-localizes to the nucleus via PP2A phosphatase. RNA-seq combined with FOXO1 overexpression/knockdown in ECs demonstrated that FOXO1 governs the VEGF-responsive tip cell-enriched genes, and further inhibits DLL4-NOTCH signaling. Endogenous FOXO1 ChIP-seq revealed that FOXO1 binds to the EC-unique tip-enriched genes with co-enrichment of EC master regulators, and the condensed chromatin region as a pioneer factor. We identified new promoter/enhancer regions of the VEGF-responsive tip cell genes regulated by FOXO1: ESM1 and ANGPT2. This is the first study to identify cell type-specific FOXO1 functions, including VEGF-mediated tip cell definition in primary cultured ECs.

Role of Fork-Head Box Genes in Breast Cancer: From Drug Resistance to Therapeutic Targets

Breast cancer has been acknowledged as one of the most notorious cancers, responsible for millions of deaths around the globe. Understanding the various factors, genetic mutations, comprehensive pathways, etc., that are involved in the development of breast cancer and how these affect the development of the disease is very important for improving and revitalizing the treatment of this global health issue. The forkhead-box gene family, comprising 19 subfamilies, is known to have a significant impact on the growth and progression of this cancer. The article looks into the various forkhead genes and how they play a role in different types of cancer. It also covers their impact on cancer drug resistance, interaction with microRNAs, explores their potential as targets for drug therapies, and their association with stem cells.

Impact of protocatechuic acid on alleviation of pulmonary damage induced by cyclophosphamide targeting peroxisome proliferator activator receptor, silent information regulator type-1, and fork head box protein in rats

Cyclophosphamide (CP) is a chemotherapeutic agent that causes pulmonary damage by generating free radicals and pro-inflammatory cytokines. Pulmonary damage has a high mortality rate due to the severe inflammation and edema occurred in lung. PPARγ/Sirt 1 signaling has been shown to be cytoprotective effect against cellular inflammatory stress and oxidative injury. Protocatechuic acid (PCA) is a potent Sirt1 activator and exhibits antioxidant as well as anti-inflammatory properties. The current study aims to investigate the therapeutic impacts of PCA against CP-induced pulmonary damage in rats. Rats were assigned randomly into 4 experimental groups. The control group was injected with a single i.p injection of saline. CP group was injected with a single i.p injection of CP (200 mg/kg). PCA groups were administered orally with PCA (50 and 100 mg/kg; p.o.) once daily for 10 consecutive days after CP injection. PCA treatment resulted in a significant decrease in the protein levels of MDA, a marker of lipid peroxidation, NO and MPO along with a significant increase in GSH and catalase protein levels. Moreover, PCA downregulated anti-inflammatory markers as IL-17, NF-κB, IKBKB, COX-2, TNF-α, and PKC and upregulated cytoprotective defenses as PPARγ, and SIRT1. In addition, PCA administration ameliorated FoxO-1 elevation, increased Nrf2 gene expression, and reduced air alveoli emphysema, bronchiolar epithelium hyperplasia and inflammatory cell infiltration induced by CP. PCA might represent a promising adjuvant to prevent pulmonary damage in patients receiving CP due to its antioxidant and anti-inflammatory effects with cytoprotective defenses.

Construction of miRNA-mRNA Regulatory Network to Identify Potential Biomarkers in Infantile Hemangioma by Integrated Bioinformatics Analysis

Infantile hemangioma (IH) is the most common vascular tumor among infants and children. However, the understanding of pathogenesis about IH has not been fully elucidated, and the potential diagnostic maker remains further explored. In this study, we aimed to find miRNAs as potential biomarkers of IH through bioinformatic analysis. The microarray datasets GSE69136, GSE100682 were downloaded from the GEO database. The co-expressed differential miRNAs were identified by analyzing these two datasets. The downstream common target genes were predicted by the ENCORI, Mirgene, miRWalk, and Targetscan databases. GO annotation and KEGG pathway enrichment analysis for target genes were performed. The STRING database and Cytoscape software were used to construct the protein-protein interaction network and screen hub genes. Then potential diagnostic markers for IH were further screened and identified by using Receiver operating characteristic curve analysis. A total of thirteen co-expressed up-regulated miRNAs were screened out in the above two datasets, and 778 down-regulated target genes were then predicted. GO annotation and KEGG pathway enrichment analysis indicated that the common target genes strongly correlated with IH. Through the DEM-hub gene network construction, six miRNAs associated with the hub genes were identified. Finally, has-miR-522-3p, has-miR-512-3p, has-miR-520a-5p with high diagnostic values were screened out by receiver operating characteristic analysis. In the study, the potential miRNA-mRNA regulatory network was firstly constructed in IH. And, the three miRNAs might be used as potential biomarkers for IH, which also provided novel strategies for the therapeutic intervention of IH.

Underlying mechanism of Qiling Jiaogulan Powder in the treatment of broiler ascites syndrome

Broiler ascites syndrome (AS), is a nutritional and metabolic disease that occurs in fast-growing commercial broiler chickens. AS can cause poor growth and a significant increase in the rate of broiler deaths, which has resulted in serious economic losses to the poultry industry. The classic traditional Chinese medicine Qiling Jiaogulan Powder (QLJP) has been demonstrated to have a certain therapeutic effect on broiler AS. However, its pharmacological mechanism remains to be elucidated. This study was performed to investigate the multitarget action mechanism of QLJP in the treatment of broiler AS based on network pharmacology analysis using a broiler AS model. First, all chemical components and targets of QLJP were obtained from the Traditional Chinese Medicine System Pharmacology Analysis Platform (TCMSP). Targets related to broiler AS were further obtained through the GeneCards database and the NCBI Gene sub-database. A protein-protein interaction (PPI) network was constructed. Then, enrichment analyses were performed to predict the potential mechanisms of QLJP in the treatment of broiler AS. Finally, the treatment effect of QLJP on AS was verified in a broiler AS model. Network pharmacology analysis generated 49 active ingredients and 167 core targets of QLJP, and a QLJP-single drug-target-disease network was successfully constructed. Gene enrichment analysis indicated that the core targets have played major roles in the Cell cycle, FOXO signaling pathways, etc. We demonstrated that QLJP improved clinical and organ damage symptoms and significantly reduced the ascites heart index in broilers with AS induced by administration of high-energy, high-protein diets and high-sodium drinking water in a low-temperature environment. QLJP may regulate lung oxidative stress, the cell cycle and apoptosis by activating the FOXO3a signaling pathway to interfere with the occurrence and development of AS in broilers. QLJP administration may be a good clinical strategy for the prevention and treatment of broiler AS.

The insulin receptor family in the heart: new light on old insights

Insulin was discovered over 100 years ago. Whilst the first half century defined many of the physiological effects of insulin, the second emphasised the mechanisms by which it elicits these effects, implicating a vast array of G proteins and their regulators, lipid and protein kinases and counteracting phosphatases, and more. Potential growth-promoting and protective effects of insulin on the heart emerged from studies of carbohydrate metabolism in the 1960s, but the insulin receptors (and the related receptor for insulin-like growth factors 1 and 2) were not defined until the 1980s. A related third receptor, the insulin receptor-related receptor remained an orphan receptor for many years until it was identified as an alkali-sensor. The mechanisms by which these receptors and the plethora of downstream signalling molecules confer cardioprotection remain elusive. Here, we review important aspects of the effects of the three insulin receptor family members in the heart. Metabolic studies are set in the context of what is now known of insulin receptor family signalling and the role of protein kinase B (PKB or Akt), and the relationship between this and cardiomyocyte survival versus death is discussed. PKB/Akt phosphorylates numerous substrates with potential for cardioprotection in the contractile cardiomyocytes and cardiac non-myocytes. Our overall conclusion is that the effects of insulin on glucose metabolism that were initially identified remain highly pertinent in managing cardiomyocyte energetics and preservation of function. This alone provides a high level of cardioprotection in the face of pathophysiological stressors such as ischaemia and myocardial infarction.

Foxc1a regulates zebrafish vascular integrity and brain vascular development through targeting amotl2a and ctnnb1

Accumulating evidences have pointed that foxc1a is essential for vascular development and integrity maintenance through regulating the expression of downstream genes and interacting with signaling pathways. However, the underling cellular and molecular mechanisms of foxc1a in regulating vascular development remain undetermined. Based on two different foxc1a mutant zebrafish lines (foxc1a^nju18 and foxc1a^nju19 which generated predicted truncated foxc1a proteins with 50aa and 315aa respectively), we found that around 30 % of foxc1a^nju18 zebrafish exhibited severe vascular developmental defects with obvious hemorrhage in hindbrain and trunk at embryonic stages. Confocal imaging analysis revealed that the formation of middle cerebral vein (MCeV), intra-cerebral central arteries (CtAs) and dorsal longitudinal vein (DLV) of brain vessels was significantly blocked in foxc1a^nju18enbryos. Injection of exogenous full length and foxc1a^nju19 truncated foxc1a mRNA both rescued the deficiency of foxc1a^nju18 embryos. Transcriptome analysis revealed 186 DEGs in foxc1a^nju18 zebrafish among which amotl2a and ctnnb1 expression were reduced and functionally associated with adherens junctions. Dual-Luciferase assays validated amotl2a and ctnnb1 were both directly transactivated by foxc1a. Rescue experiments demonstrated that amotl2a was mainly responsible for the vascular integrity caused by foxc1a mutation and also coordinated with ctnnb1 to regulate brain vascular development. Our data point to a novel clue that foxc1a regulates vascular integrity and brain vascular development through targeting amotl2a and ctnnb1.

Linoleic Acid Attenuates Denervation-Induced Skeletal Muscle Atrophy in Mice through Regulation of Reactive Oxygen Species-Dependent Signaling

Muscle atrophy is a major muscle disease, the symptoms of which include decreased muscle volume leading to insufficient muscular support during exercise. One cause of muscle atrophy is the induction of oxidative stress by reactive oxygen species (ROS). This study aimed to identify the antioxidant mechanism of linoleic acid (LA) in muscle atrophy caused by oxidative stress. H2O2 has been used to induce oxidative stress in myoblasts in vitro. C2C12 myoblasts treated with H2O2 exhibited decreased viability and increased ROS synthesis. However, with LA treatment, the cells tended to recover from oxidative effects similar to those of the control groups. At the molecular level, the expression of superoxide dismutase 1 (SOD1), Bax, heat shock protein 70 (HSP70), and phosphorylated forkhead box protein O1 was increased by oxidative stress, causing apoptosis. LA treatment suppressed these changes. In addition, the expression of MuRF1 and Atrogin-1/MAFbx mRNA increased under oxidative stress but not in the LA-treated group. Sciatic denervation of C57BL/6 mice manifested as atrophy of the skeletal muscle in micro-computed tomography (micro-CT). The protein expression levels of SOD1, HSP70, and MuRF1 did not differ between the atrophied muscle tissues and C2C12 myoblasts under oxidative stress. With LA treatment, muscle atrophy recovered and protein expression was restored to levels similar to those in the control. Therefore, this study suggests that LA may be a candidate substance for preventing muscle atrophy.

Role of Forkhead Box Protein O1 (FoxO1) in Stroke: A Literature Review

Stroke is one of the most prevalent causes of death around the world. When a stroke occurs, many cellular signaling cascades and regulators are activated, which results in severe cellular dysfunction and debilitating long-term disability. One crucial regulator of cell fate and function is mammalian Forkhead box protein O1 (FoxO1). Many studies have found FoxO1 to be implicated in many cellular processes, including regulating gluconeogenesis and glycogenolysis. During a stroke, modifications of FoxO1 have been linked to a variety of functions, such as inducing cell death and inflammation, inhibiting oxidative injury, affecting the blood brain barrier (BBB), and regulating hepatic gluconeogenesis. For these functions of FoxO1, different measures and treatments were applied to FoxO1 after ischemia. However, the subtle mechanisms of post-transcriptional modification and the role of FoxO1 are still elusive and even contradictory in the development of stroke. The determination of these mechanisms will lead to further enlightenment for FoxO1 signal transduction and the identification of targeted drugs. The regulation and function of FoxO1 may provide an important way for the prevention and treatment of diseases. Overall, the functions of FoxO1 are multifactorial, and this paper will summarize all of the significant pathways in which FoxO1 plays an important role during stroke damage and recovery.

Phytochemical‑rich herbal formula ATG‑125 protects against sucrose‑induced gastrocnemius muscle atrophy by rescuing Akt signaling and improving mitochondrial dysfunction in young adult mice

The antioxidant capability of herbal remedies has attracted widespread attention, but their molecular mechanisms in a muscle atrophy model have not been explored. The aim of the present study was to compare the bioactivity of sucrose challenged mice following treatment with ATG‑125. Here, through a combination of transcriptomic and biomedical analysis, herbal formula ATG‑125, a phytochemical‑rich formula, was identified as a protective factor against muscle atrophy in sucrose challenged mice. Gene ontology (GO) identified differentially expressed genes that were primarily enriched in the 'negative regulation of proteolysis', 'cellular amino acid metabolic process', 'lipoprotein particle' and 'cell cycle', all of which were associated with the ATG‑125‑mediated prevention of muscle atrophy, particularly with regard to mitochondrial biogenesis. In skeletal muscle, a set of mitochondrial‑related genes, including angiopoietin‑like 4, nicotinamide riboside kinase 2 (Nmrk2), pyruvate dehydrogenase lipoamide kinase isozyme 4, Asc‑type amino acid transporter 1 and mitochondrial uncoupling protein 3 (Ucp3) were markedly upregulated following ATG‑125 intervention. An increase in Nmrk2 and Ucp3 expression were noted after ATG‑125 treatment, in parallel with upregulation of the 'nicotinate and nicotinamide metabolism' pathway, as determined using the Kyoto Encyclopedia of Genes and Genomes (KEGG). Furthermore, KEGG pathway analysis revealed the downregulation of 'complement and coagulation cascades', 'cholesterol metabolism', 'biosynthesis of amino acids' and 'PPAR signaling pathway', which were associated with the downregulation of serine (or cysteine) peptidase inhibitor clade A member (Serpina)3, Serpina1b, Serpina1d, Serpina1e, apolipoprotein (Apo)a1 and Apoa2, all of which were cardiovascular and diabetes‑associated risk factors and were regulated by ATG‑125. In addition, ATG‑125 treatment resulted in downregulated mRNA expression levels of ATPase sarcoplasmic/endoplasmic reticulum Ca2+ transporting 2, troponin‑I1, troponin‑C1 and troponin‑T1 in young adult gastrocnemius muscle compared with the sucrose group. Nuclear factor‑κB‑hypoxia inducible factor‑1α‑TGFβ receptor type‑II‑vascular endothelial growth factor staining indicated that ATG‑125 decreased sucrose‑induced chronic inflammation. ATG‑125 was sufficient to prevent muscle atrophy, and this protective effect may be mediated through upregulation of AKT phosphorylation, upregulating the insulin growth factor‑1R‑insulin receptor substrate‑PI3K‑AKT pathway, which in turn resulted in a forkhead box O‑dependent decrease in protein degradation pathways, including regulation of atrogin1 and E3 ubiquitin‑protein ligase TRIM63. Peroxisome‑proliferator activated receptor γ coactivator 1α (PGC1α) was decreased in young adult mice challenged with sucrose. ATG‑125 treatment significantly increased PGC1α and significantly increased UCP‑1,2,3 expression levels, which suggested ATG‑125 poised the mitochondria for uncoupling of respiration. This effect is consistent with the increased SIRT1 levels and may explain an increase in mitochondria biogenesis. Taken together, the present study showed that ATG‑125, as an integrator of protein synthesis and degradative pathways, prevented muscle wasting.

Endothelial SIRT1 as a Target for the Prevention of Arterial Aging: Promises and Challenges

ABSTRACT

SIRT1, a member of the sirtuin family of longevity regulators, possesses potent activities preventing vascular aging. The expression and function of SIRT1 in endothelial cells are downregulated with age, in turn causing early vascular aging and predisposing various vascular abnormalities. Overexpression of SIRT1 in the vascular endothelium prevents aging-associated endothelial dysfunction and senescence, thus the development of hypertension and atherosclerosis. Numerous efforts have been directed to increase SIRT1 signaling as a potential strategy for different aging-associated diseases. However, the complex mechanisms underlying the regulation of SIRT1 have posed a significant challenge toward the design of specific and effective therapeutics. This review aimed to provide a summary on the regulation and function of SIRT1 in the vascular endothelium and to discuss the different approaches targeting this molecule for the prevention and treatment of age-related cardiovascular and cerebrovascular diseases.

Development and physiological functions of the lymphatic system: insights from human genetic studies of primary lymphedema

Primary lymphedema is a long-term (chronic) condition characterized by tissue lymph retention and swelling that can affect any part of the body, although it usually develops in the arms or legs. Due to the relevant contribution of the lymphatic system to human physiology, while this review mainly focuses on the clinical and physiological aspects related to the regulation of fluid homeostasis and edema, clinicians need to know that the impact of lymphatic dysfunction with a genetic origin can be wide ranging. Lymphatic dysfunction can affect immune function so leading to infection; it can influence cancer development and spread, and it can determine fat transport so impacting on nutrition and obesity. Genetic studies and the development of imaging techniques for the assessment of lymphatic function have enabled the recognition of primary lymphedema as a heterogenic condition in terms of genetic causes and disease mechanisms. In this review, the known biological functions of several genes crucial to the development and function of the lymphatic system are used as a basis for understanding normal lymphatic biology. The disease conditions originating from mutations in these genes are discussed together with a detailed clinical description of the phenotype and the up-to-date knowledge in terms of disease mechanisms acquired from in vitro and in vivo research models.

Detection of Novel Potential Regulators of Stem Cell Differentiation and Cardiogenesis through Combined Genome-Wide Profiling of Protein-Coding Transcripts and microRNAs

In vitro differentiation of embryonic stem cells (ESCs) provides a convenient basis for the study of microRNA-based gene regulation that is relevant for early cardiogenic processes. However, to which degree insights gained from in vitro differentiation models can be readily transferred to the in vivo system remains unclear. In this study, we profiled simultaneous genome-wide measurements of mRNAs and microRNAs (miRNAs) of differentiating murine ESCs (mESCs) and integrated putative miRNA-gene interactions to assess miRNA-driven gene regulation. To identify interactions conserved between in vivo and in vitro, we combined our analysis with a recent transcriptomic study of early murine heart development in vivo. We detected over 200 putative miRNA-mRNA interactions with conserved expression patterns that were indicative of gene regulation across the in vitro and in vivo studies. A substantial proportion of candidate interactions have been already linked to cardiogenesis, supporting the validity of our approach. Notably, we also detected miRNAs with expression patterns that closely resembled those of key developmental transcription factors. The approach taken in this study enabled the identification of miRNA interactions in in vitro models with potential relevance for early cardiogenic development. Such comparative approaches will be important for the faithful application of stem cells in cardiovascular research.

Endothelium-specific depletion of LRP1 improves glucose homeostasis through inducing osteocalcin

The vascular endothelium is present within metabolic organs and actively regulates energy metabolism. Here we show osteocalcin, recognized as a bone-secreted metabolic hormone, is expressed in mouse primary endothelial cells isolated from heart, lung and liver. In human osteocalcin promoter-driven green fluorescent protein transgenic mice, green fluorescent protein signals are enriched in endothelial cells lining aorta, small vessels and capillaries and abundant in aorta, skeletal muscle and eye of adult mice. The depletion of lipoprotein receptor-related protein 1 induces osteocalcin through a Forkhead box O -dependent pathway in endothelial cells. Whereas depletion of osteocalcin abolishes the glucose-lowering effect of low-density lipoprotein receptor-related protein 1 depletion, osteocalcin treatment normalizes hyperglycemia in multiple mouse models. Mechanistically, osteocalcin receptor-G protein-coupled receptor family C group 6 member A and insulin-like-growth-factor-1 receptor are in the same complex with osteocalcin and required for osteocalcin-promoted insulin signaling pathway. Therefore, our results reveal an endocrine/paracrine role of endothelial cells in regulating insulin sensitivity, which may have therapeutic implications in treating diabetes and insulin resistance through manipulating vascular endothelium.

Nicotinamide N-methyltransferase in endothelium protects against oxidant stress-induced endothelial injury

Nicotinamide N-methyltransferase (NNMT, EC 2.1.1.1.) plays an important role in the growth of many different tumours and is also involved in various non-neoplastic disorders. However, the presence and role of NNMT in the endothelium has yet to be specifically explored. Here, we characterized the functional activity of NNMT in the endothelium and tested whether NNMT regulates endothelial cell viability. NNMT in endothelial cells (HAEC, HMEC-1 and EA.hy926) was inhibited using two approaches: pharmacological inhibition of the enzyme by NNMT inhibitors (5-amino-1-methylquinoline - 5MQ and 6-methoxynicotinamide - JBSF-88) or by shRNA-mediated silencing. Functional inhibition of NNMT was confirmed by LC/MS/MS-based analysis of impaired MNA production. The effects of NNMT inhibition on cellular viability were analyzed in both the absence and presence of menadione. Our results revealed that all studied endothelial lines express relatively high levels of functionally active NNMT compared with cancer cells (MDA-MB-231). Although the aldehyde oxidase 1 enzyme was also expressed in the endothelium, the further metabolites of N1-methylnicotinamide (N1-methyl-2-pyridone-5-carboxamide and N1-methyl-4-pyridone-3-carboxamide) generated by this enzyme were not detected, suggesting that endothelial NNMT-derived MNA was not subsequently metabolized in the endothelium by aldehyde oxidase 1. Menadione induced a concentration-dependent decrease in endothelial viability as evidenced by a decrease in cell number that was associated with the upregulation of NNMT and SIRT1 expression in the nucleus in viable cells. The suppression of the NNMT activity either by NNMT inhibitors or shRNA-based silencing significantly decreased the endothelial cell viability in response to menadione. Furthermore, NNMT inhibition resulted in nuclear SIRT1 expression downregulation and upregulation of the phosphorylated form of SIRT1 on Ser47. In conclusion, our results suggest that the endothelial nuclear NNMT/SIRT1 pathway exerts a cytoprotective role that safeguards endothelial cell viability under oxidant stress insult.

Shear stress inhibits cardiac microvascular endothelial cells apoptosis to protect against myocardial ischemia reperfusion injury via YAP/miR-206/PDCD4 signaling pathway

Cardiac microvascular endothelial cells (CMECs), derived from coronary circulation microvessel, are the main barrier for the exchange of energy and nutrients between myocardium and blood. However, microvascular I/R injury is a severely neglected topic, and few strategies can reverse this pathology. In this study, we investigated the mechanism of shear stress in microvascular I/R injury, and try to elucidate the downstream signaling pathways that inhibit CMECs apoptosis to reduce I/R injury. Our results demonstrated that shear stress inhibited the apoptosis protein, increased PECAM-1 expression and eNOS phosphorylation in hypoxia reoxygenated (H/R) CMECs. The mechanism of shear stress was related to up-regulated expression of YAP, the increased number of YAP entering the nucleus by dephosphorylation, the reduced number of TUNEL positive cells, increased miR-206 and inhibited protein level of PDCD4 in CMECs. However, siRNA-mediated knockdown of YAP abolished the protective effects of shear stress on CMECs apoptosis, similar results obtained from administration with AMO-miR-206, and also prevented PDCD4 (target gene of miR-206) increasing when treatment with both AMO-miR-206 and mimics-miR-206. In vivo, restoring the blood fluid with nitroglycerin (NTG) to mimic in vitro shear stress levels, which subsequently improved cardiac function, reduced infarcted area, lowered microvascular perfusion defects. Functional investigations clearly illustrated that increased the protein expression of PECAM-1 and eNOS phosphorylation, activated YAP, strengthened miR-206 expression, and suppressed PDCD4 expression. In summary, this study confirmed that shear stress reversed CMECs apoptosis, relieved microvascular I/R injury, the mechanism of which involving through YAP/miR-206/PDCD4 signaling pathway to finally suppress myocardial I/R injury.

Cilostazol preconditioning alleviates cyclophosphamide-induced cardiotoxicity in male rats: Mechanistic insights into SIRT1 signaling pathway

AIMS

Cyclophosphamide (CYP) is a potent anticancer agent with well-known cardiotoxicity that limits its clinical applications. Cilostazol is a vosodilating drug, showing a cardioprotective effect in some cardiac disorders; however its effect in CYP-induced cardiotoxicity is still uncertain. We investigated the effect of cilostazol against CYP-induced cardiotoxicity and the contribution of SIRT1 signaling.

MATERIALS AND METHODS

7 week-old male Wistar albino rats were treated with cilostazol (30 mg/kg/day, orally) in the absence or presence of SIRT1 inhibitor, EX-527 (5 mg/kg/day, IP) for 10 days and injected with CYP (200 mg/kg, IP) on the 7th day of the study. Age-matched rats were used as control group. On the 11th day, hearts were harvested for biochemical, immunoblotting and histological analyses. Markers of cardiac injury were assessed in plasma samples.

KEY FINDINGS

CYP injection contributed to cardiac injury manifested as significant increases in plasma activities of heart enzymes and cardiac troponin I levels. Cilostazol attenuated cardiac injury and minimized the histological lesions in hearts of CYP-treated rats. Cilostazol induced 3 fold up-regulation of SIRT1 and promoted the antioxidant defense response through FoxO1-related mechanism in hearts of CYP-treated rats. Cilostazol suppressed the CYP-induced up-regulation of PARP1 and p53, and blocked the NF-kB p65-mediated inflammatory response in hearts of CYP-treated rats. All the beneficial effects of cilostazol were almost abolished by EX-527.

SIGNIFICANCE

These data provided insights into the mechanism underlying the cardioprotective effect of cilostazol in CYP-treated rats through upregulation of SIRT1 signaling, suggesting that cilostazol might be a candidate modality for CYP-induced cardiotoxicity.

FoxC1-Induced Vascular Niche Improves Survival and Myocardial Repair of Mesenchymal Stem Cells in Infarcted Hearts

Aims

Forkhead box C1 (FoxC1) is essential for maintaining the hair follicle stem cell niche. The role of FoxC1 in maintaining mesenchymal stem cell (MSC) niches after myocardial infarction (MI) has not been directly determined to date. In this study, we determined to explore the possible roles and mechanisms of FoxC1 on MSC survival and function in the ischemic niche.

Methods and Results

MI model was established in this study, and expression level of FoxC1 was overexpressed or knocked down through efficient delivery of FoxC1 transfection or siFoxC1. Fifteen days later, the animals were allocated randomly to receive phosphate-buffered saline (PBS) injection or MSC transplantation. We identified FoxC1 as a key regulator of maintaining the vascular niche in the infarcted hearts (IHs) by driving proangiogenic and anti-inflammatory cytokines while repressing inflammatory and fibrotic factor expression. This vascular niche improved MSC survival and capacity in the IHs. Importantly, FoxC1 interacted with MSCs and was required for vessel specification and differentiation of engrafted MSCs in the ischemic niches, promoting myocardial repair. Inhibiting FoxC1 abolished these effects.

Conclusion

These results definitively implicate FoxC1 signaling in maintaining ischemic vascular niche, which may be helpful in myocardial repair induced by MSC therapy.

Metformin alleviates oxidative stress and enhances autophagy in diabetic kidney disease via AMPK/SIRT1-FoxO1 pathway

Metformin, as the basic pharmacological therapy and the first preventive drug in type 2 diabetes mellitus (T2DM), is proved to have potential protection in diabetic kidney disease (DKD). Here, we established a diabetic rat model induced by high-fat diet and low dose streptozotocin, and high glucose cultured rat mesangial cells (RMCs) pre-treated with metformin or transfected with AMPK, SIRT1 and FoxO1 small interfering RNA, and detected oxidative stress and autophagy related factors to explore the molecular mechanisms of metformin on DKD via adenosine monophosphate-activated protein kinase (AMPK)/silent mating type information regulation 2 homolog-1 (sirtuin-1, SIRT1)-Forkhead box protein O1 (FoxO1) pathway. We found that metformin effectively alleviated the disorders of glycolipid metabolism, renal function injury in diabetic rats, and relieved oxidative stress, enhanced autophagy and slowed down abnormal cell proliferation in high glucose cultured RMCs through AMPK/SIRT1-FoxO1 pathway, indicating the protective role of metformin against the pathological process of DKD.

Selective Heart Irradiation Induces Cardiac Overexpression of the Pro-hypertrophic miR-212

Background: A deleterious, late-onset side effect of thoracic radiotherapy is the development of radiation-induced heart disease (RIHD). It covers a spectrum of cardiac pathology including also heart failure with preserved ejection fraction (HFpEF) characterized by left ventricular hypertrophy (LVH) and diastolic dysfunction. MicroRNA-212 (miR-212) is a crucial regulator of pathologic LVH via FOXO3-mediated pathways in pressure-overload-induced heart failure. We aimed to investigate whether miR-212 and its selected hypertrophy-associated targets play a role in the development of RIHD. Methods: RIHD was induced by selective heart irradiation (50 Gy) in a clinically relevant rat model. One, three, and nineteen weeks after selective heart irradiation, transthoracic echocardiography was performed to monitor cardiac morphology and function. Cardiomyocyte hypertrophy and fibrosis were assessed by histology at week 19. qRT-PCR was performed to measure the gene expression changes of miR-212 and forkhead box O3 (FOXO3) in all follow-up time points. The cardiac transcript level of other selected hypertrophy-associated targets of miR-212 including extracellular signal-regulated kinase 2 (ERK2), myocyte enhancer factor 2a (MEF2a), AMP-activated protein kinase, (AMPK), heat shock protein 40 (HSP40), sirtuin 1, (SIRT1), calcineurin A-alpha and phosphatase and tensin homolog (PTEN) were also measured at week 19. Cardiac expression of FOXO3 and phospho-FOXO3 were investigated at the protein level by Western blot at week 19. Results: In RIHD, diastolic dysfunction was present at every time point. Septal hypertrophy developed at week 3 and a marked LVH with interstitial fibrosis developed at week 19 in the irradiated hearts. In RIHD, cardiac miR-212 was overexpressed at week 3 and 19, and FOXO3 was repressed at the mRNA level only at week 19. In contrast, the total FOXO3 protein level failed to decrease in response to heart irradiation at week 19. Other selected hypertrophy-associated target genes failed to change at the mRNA level in RIHD at week 19. Conclusions: LVH in RIHD was associated with cardiac overexpression of miR-212. However, miR-212 seems to play a role in the development of LVH via FOXO3-independent mechanisms in RIHD. As a central regulator of pathologic remodeling, miR-212 might become a novel target for RIHD-induced LVH and heart failure.

Role of Akirin1 in the regulation of skeletal muscle fiber-type switch

Akirin1 is a highly conserved ubiquitously expressed nuclear protein. Owing to its strong nuclear localization signal and protein-protein interaction properties, Akirin1 has been speculated to regulate transcription of target genes as a cofactor. Previous studies have reported Akirin1 as a downstream target of myostatin, a potent negative regulator of myogenesis. Mice lacking myostatin displayed enhanced Akirin1 gene expression. Further, in vitro evidence has shown Akirin1 overexpression leads to hypertrophy in C₂ C ₁₂ myotubes. In this study, we used Akirin1 knockout mice as a model system to further elucidate the function of Akirin1 in fully differentiated skeletal muscle. Akirin1 knockout mice did not show any obvious phenotypic difference when compared with wild type. However, promoter-reporter assay suggested that Akirin1 regulated the transcription of muscle-specific RING finger 1 (MuRF-1), an important E3 ubiquitin ligase in skeletal muscle. Furthermore, ablation of Akirin1 resulted in increased type IIa and decreased type I muscle fibers, which was further supported by an increase in Myh2 and decrease in Myh7 gene expression. Also, histochemical studies for succinate dehydrogenase activity revealed a less oxidative muscle in the absence of Akirin1. Together, our study suggests a novel role of Akirin1 in maintaining the muscle fiber type and regulation of the metabolic activity of the skeletal muscle.

Methodological Approach for the Evaluation of FOXO as a Positive Regulator of Antioxidant Genes

All four FOXO isoforms have been shown to respond to changes in the cellular redox status of the cell, and regulate the expression of target genes that in turn can modulate the cellular oxidative status. However, the mechanisms involved are still controversial. It is clear though that redox regulation of FOXO factors occurs at different levels. The proteins themselves are redox-sensitive and their capacity to bind their target sites seems to be at least partially dependent on their oxidative status. Importantly, several of the cofactors that are known to regulate FOXO transcriptional activity are also sensitive to changes in the cellular redox status, in particular the deacetylase SirT1 is activated in response to reduced levels of reducing equivalents (increased NAD⁺/NADH⁺ ratio) and the coactivator PGC-1α is induced in response to increased cellular oxidative stress. Furthermore, nuclear localization of FOXO factors is also regulated by proteins that, like AKT, are themselves regulated directly or indirectly by the cellular levels of reactive oxygen and nitrogen species. In this technical review, we aim to update the current status of our knowledge of how to handle redox-regulated FOXO factor research in order to better understand FOXO biology.

Understanding the perspectives of forkhead transcription factors in delayed wound healing

Wound healing is a complex overlapping biological process that involves a sequence of events coordinated by various cells, proteins, growth factors, cytokines and signaling molecules. Recent evidence indicates that forkhead box O1 (FOXO1) transcription factors play an important role in organizing these events to stimulate wound healing. The ubiquitously expressed forkhead box, class O (FOXO) transcription factors act as cell signaling molecules in various transcriptional processes that are involved in diverse cellular activities, including cell death, cell differentiation, DNA repair, apoptosis, and oxidative stress in response to stimuli, and interact with numerous proteins. Due to the activation of FOXO targeted genes, FOXOs are involved in maintaining the balance between oxidative stress and antioxidants. In humans, different isoforms of FOXO namely FOXO1, FOXO3, FOXO4 and FOXO6 are present, however only FOXO1 and FOXO3 possess biological functions such as morphogenesis, maintenance and tissue regeneration. This might make FOXOs an important therapeutic target to enhance wound healing in diabetes, and to avoid over scarring. In spite of extensive literature, little is known regarding the role of FOXO and its relationship in wound healing. This review provides a summary of FOXO proteins and their biological role in wound healing and oxidative stress.

Chronic kidney disease induces left ventricular overexpression of the pro-hypertrophic microRNA-212

Chronic kidney disease (CKD) is a public health problem that increases the risk of cardiovascular morbidity and mortality. Heart failure with preserved ejection fraction (HFpEF) characterized by left ventricular hypertrophy (LVH) and diastolic dysfunction is a common cardiovascular complication of CKD. MicroRNA-212 (miR-212) has been demonstrated previously to be a crucial regulator of pathologic LVH in pressure-overload-induced heart failure via regulating the forkhead box O3 (FOXO3)/calcineurin/nuclear factor of activated T-cells (NFAT) pathway. Here we aimed to investigate whether miR-212 and its hypertrophy-associated targets including FOXO3, extracellular signal-regulated kinase 2 (ERK2), and AMP-activated protein kinase (AMPK) play a role in the development of HFpEF in CKD. CKD was induced by 5/6 nephrectomy in male Wistar rats. Echocardiography and histology revealed LVH, fibrosis, preserved systolic function, and diastolic dysfunction in the CKD group as compared to sham-operated animals eight and/or nine weeks later. Left ventricular miR-212 was significantly overexpressed in CKD. However, expressions of FOXO3, AMPK, and ERK2 failed to change significantly at the mRNA or protein level. The protein kinase B (AKT)/FOXO3 and AKT/mammalian target of rapamycin (mTOR) pathways are also proposed regulators of LVH induced by pressure-overload. Interestingly, phospho-AKT/total-AKT ratio was increased in CKD without significantly affecting phosphorylation of FOXO3 or mTOR. In summary, cardiac overexpression of miR-212 in CKD failed to affect its previously implicated hypertrophy-associated downstream targets. Thus, the molecular mechanism of the development of LVH in CKD seems to be independent of the FOXO3, ERK1/2, AMPK, and AKT/mTOR-mediated pathways indicating unique features in this form of LVH.

Expression of a Functional IL-2 Receptor in Vascular Smooth Muscle Cells

Many nonlymphoid cell types express at least two, if not all three, subunits of the IL-2R; although, compared with lymphocytes, relatively little is known about how IL-2 affects the function of nonlymphoid cells. The limited information available suggests that IL-2 has a substantial impact on cells such as gastrointestinal epithelial cells, endothelial cells, and fibroblasts. In a previous report from our laboratory, we noted that IL-2 and IL-2Rβ-deficient mice lose smooth muscle cells over time, eventually resulting in aneurysmal aortas and ectatic esophagi. This finding, combined with our work showing that IL-2 surrounds vascular smooth muscle cells by association with perlecan, led us to ask whether vascular smooth muscle cells express an IL-2R. Toward this end, we reported the expression of IL-2Rβ on human and murine vascular smooth muscle cells. We now report that vascular smooth muscle cells express all three subunits of the IL-2R, and that expression of IL-2Rα varies with vascular smooth muscle cell phenotype. Furthermore, we show that, through a functional IL-2R, IL-2 initiates signaling pathways and impacts vascular smooth muscle cell function. Finally, we demonstrate that IL-2 expression increases upon initiation of conditions that promote intimal hyperplasia, suggesting a mechanism by which the IL-2/IL-2R system may impact this widespread vascular pathology.

The Dominant Role of Forkhead Box Proteins in Cancer

Forkhead box (FOX) proteins are multifaceted transcription factors that are significantly implicated in cancer, with various critical roles in biological processes. Herein, we provide an overview of several key members of the FOXA, FOXC, FOXM1, FOXO and FOXP subfamilies. Important pathophysiological processes of FOX transcription factors at multiple levels in a context-dependent manner are discussed. We also specifically summarize some major aspects of FOX transcription factors in association with cancer research such as drug resistance, tumor growth, genomic alterations or drivers of initiation. Finally, we suggest that targeting FOX proteins may be a potential therapeutic strategy to combat cancer.

Morphology regulation in vascular endothelial cells

Morphological change in endothelial cells is an initial and crucial step in the process of establishing a functional vascular network. Following or associated with differentiation and proliferation, endothelial cells elongate and assemble into linear cord-like vessels, subsequently forming a perfusable vascular tube. In vivo and in vitro studies have begun to outline the underlying genetic and signaling mechanisms behind endothelial cell morphology regulation. This review focuses on the transcription factors and signaling pathways regulating endothelial cell behavior, involved in morphology, during vascular development.

FOXO Signaling Pathways as Therapeutic Targets in Cancer

Many transcription factors play a key role in cellular differentiation and the delineation of cell phenotype. Transcription factors are regulated by phosphorylation, ubiquitination, acetylation/deacetylation and interactions between two or more proteins controlling multiple signaling pathways. These pathways regulate different physiological processes and pathological events, such as cancer and other diseases. The Forkhead box O (FOXO) is one subfamily of the fork head transcription factor family with important roles in cell fate decisions and this subfamily is also suggested to play a pivotal functional role as a tumor suppressor in a wide range of cancers. During apoptosis, FOXOs are involved in mitochondria-dependent and -independent processes triggering the expression of death receptor ligands like Fas ligand, TNF apoptosis ligand and Bcl‑X_L, bNIP3, Bim from Bcl-2 family members. Different types of growth factors like insulin play a vital role in the regulation of FOXOs. The most important pathway interacting with FOXO in different types of cancers is the PI3K/AKT pathway. Some other important pathways such as the Ras-MEK-ERK, IKK and AMPK pathways are also associated with FOXOs in tumorigenesis. Therapeutically targeting the FOXO signaling pathway(s) could lead to the discovery and development of efficacious agents against some cancers, but this requires an enhanced understanding and knowledge of FOXO transcription factors and their regulation and functioning. This review focused on the current understanding of cell biology of FOXO transcription factors which relates to their potential role as targets for the treatment and prevention of human cancers. We also discuss drugs which are currently being used for cancer treatment along with their target pathways and also point out some potential drawbacks of those drugs, which further signifies the need for development of new drug strategies in the field of cancer treatment.

Vascular ageing: Underlying mechanisms and clinical implications

Epidemiological studies have shown that ageing is a major non-reversible risk factor for cardiovascular disease. Vascular ageing starts early in life and is characterized by a gradual change of vascular structure and function resulting in increased arterial stiffening. At the present review we discuss the role of the most important molecular pathways involved in vascular ageing, their association with arterial stiffening and possible novel therapeutic targets that may delay this otherwise irreversible degenerating process. Specifically, we discuss the role of oxidative stress, telomere shortening, and ubiquitin proteasome system in endothelial cell senescence and dysfunction in vascular inflammation and in arterial stiffening. Further, we summarize the most important molecular mechanisms regulating vascular ageing including sirtuin 1, telomerase, klotho, JunD, and amyloid beta 1-40 peptide.

Insulin receptor substrate signaling controls cardiac energy metabolism and heart failure

The heart is an insulin-dependent and energy-consuming organ in which insulin and nutritional signaling integrates to the regulation of cardiac metabolism, growth and survival. Heart failure is highly associated with insulin resistance, and heart failure patients suffer from the cardiac energy deficiency and structural and functional dysfunction. Chronic pathological conditions, such as obesity and type 2 diabetes mellitus, involve various mechanisms in promoting heart failure by remodeling metabolic pathways, modulating cardiac energetics and impairing cardiac contractility. Recent studies demonstrated that insulin receptor substrates 1 and 2 (IRS-1,-2) are major mediators of both insulin and insulin-like growth factor-1 (IGF-1) signaling responsible for myocardial energetics, structure, function and organismal survival. Importantly, the insulin receptor substrates (IRS) play an important role in the activation of the phosphatidylinositide-3-dependent kinase (PI-3K) that controls Akt and Foxo1 signaling cascade, regulating the mitochondrial function, cardiac energy metabolism and the renin-angiotensin system. Dysregulation of this branch in signaling cascades by insulin resistance in the heart through the endocrine system promotes heart failure, providing a novel mechanism for diabetic cardiomyopathy. Therefore, targeting this branch of IRS→PI-3K→Foxo1 signaling cascade and associated pathways may provide a fundamental strategy for the therapeutic and nutritional development in control of metabolic and cardiovascular diseases. In this review, we focus on insulin signaling and resistance in the heart and the role energetics play in cardiac metabolism, structure and function.

Low circulating microRNA levels in heart failure patients are associated with atherosclerotic disease and cardiovascular-related rehospitalizations

OBJECTIVE

Circulating microRNAs (miRNAs) have been implicated in both heart failure and atherosclerotic disease. The aim of this study was to examine associations between heart failure specific circulating miRNAs, atherosclerotic disease and cardiovascular-related outcome in patients with heart failure.

METHODS

The levels of 11 heart failure-specific circulating miRNAs were compared in plasma of 114 heart failure patients with and without different manifestations of atherosclerotic disease. We then studied these miRNAs in relation to biomarkers associated to atherosclerosis and to cardiovascular-related rehospitalizations during 18 months of follow-up.

RESULTS

At least one manifestation of atherosclerotic disease was found in 70 (61%) of the heart failure patients. A consistent trend was found between an increasing number of manifestations of atherosclerosis (peripheral arterial disease in specific), and lower levels of miR-18a-5p, miR-27a-3p, miR-199a-3p, miR-223-3p and miR-652-3p (all P < 0.05). Target prediction and network analyses identified several interactions between miRNA targets and biomarkers related to inflammation, angiogenesis and endothelial dysfunction. Lower miRNA levels were associated with higher levels of these atherosclerosis-related biomarkers. In addition, lower miRNA levels were significantly associated with rehospitalizations due to cardiovascular causes within 18 months, with let-7i-5p as strongest predictor [HR 2.06 (95% CI 1.29-3.28), C-index 0.70, P = 0.002].

CONCLUSIONS

A consistent pattern of lower levels of circulating miRNAs was found in heart failure patients with atherosclerotic disease, in particular peripheral arterial disease. In addition, lower levels of miRNAs were associated with higher levels of biomarkers involved in atherosclerosis and an increased risk of a cardiovascular-related rehospitalization.

Metformin inhibits estrogen-dependent endometrial cancer cell growth by activating the AMPK-FOXO1 signal pathway

Metformin is an oral biguanide commonly used for treating type II diabetes and has recently been reported to possess antiproliferative properties that can be exploited for the prevention and treatment of a variety of cancers. The mechanisms underlying this effect have not been fully elucidated. Our study shows a marked loss of AMP-activated protein kinase (AMPK) phosphorylation and nuclear human Forkhead box O1 (FOXO1) protein in estrogen-dependent endometrial cancer (EC) tumors compared to normal control endometrium. Metformin treatment suppressed EC cell growth in a time-dependent manner in vitro; this effect was cancelled by cotreatment with an AMPK inhibitor, compound C. Metformin decreased FOXO1 phosphorylation and increased FOXO1 nuclear localization in Ishikawa and HEC-1B cells, with non-significant increase in FOXO1 mRNA expression. Moreover, compound C blocked the metformin-induced changes of FOXO1 and its phosphorylation protein, suggesting that metformin upregulated FOXO1 activity by AMPK activation. Similar results were obtained after treatment with insulin. In addition, transfection with siRNA for FOXO1 cancelled metformin-inhibited cell growth, indicating that FOXO1 mediated metformin to inhibit EC cell proliferation. A xenograft mouse model further revealed that metformin suppressed HEC-1B tumor growth, accompanied by downregulated ki-67 and upregulated AMPK phosphorylation and nuclear FOXO1 protein. Taken together, these data provide a novel mechanism of antineoplastic effect for metformin through the regulation of FOXO1, and suggest that the AMPK-FOXO1 pathway may be a therapeutic target to the development of new antineoplastic drugs.

Genome-Wide Transcriptome and Binding Sites Analyses Identify Early FOX Expressions for Enhancing Cardiomyogenesis Efficiency of hESC Cultures

The differentiation efficiency of human embryonic stem cells (hESCs) into heart muscle cells (cardiomyocytes) is highly sensitive to culture conditions. To elucidate the regulatory mechanisms involved, we investigated hESCs grown on three distinct culture platforms: feeder-free Matrigel, mouse embryonic fibroblast feeders, and Matrigel replated on feeders. At the outset, we profiled and quantified their differentiation efficiency, transcriptome, transcription factor binding sites and DNA-methylation. Subsequent genome-wide analyses allowed us to reconstruct the relevant interactome, thereby forming the regulatory basis for implicating the contrasting differentiation efficiency of the culture conditions. We hypothesized that the parental expressions of FOXC1, FOXD1 and FOXQ1 transcription factors (TFs) are correlative with eventual cardiomyogenic outcome. Through WNT induction of the FOX TFs, we observed the co-activation of WNT3 and EOMES which are potent inducers of mesoderm differentiation. The result strengthened our hypothesis on the regulatory role of the FOX TFs in enhancing mesoderm differentiation capacity of hESCs. Importantly, the final proportions of cells expressing cardiac markers were directly correlated to the strength of FOX inductions within 72 hours after initiation of differentiation across different cell lines and protocols. Thus, we affirmed the relationship between early FOX TF expressions and cardiomyogenesis efficiency.

Glycyrrhetinic acid protects H9c2 cells from oxygen glucose deprivation-induced injury through the PI3K/AKt signaling pathway

Glycyrrhetinic acid (GA) is an ingredient of triterpene saponins found in Gancao (Radix Glycyrrhizae). Here, we investigated the protective effects of GA in H9c2 cells, and explored its possible mechanism of action. Different concentrations of GA were used to treat H9c2 cells under oxygen glucose deprivation. We analyzed cell necrosis and apoptosis using optical microscopy, Hoechst 33342 staining, FITC-annexin V/PI double-staining and lactate dehydrogenase (LDH), creatine kinase-MB (CK-MB) and interleukin (IL)-1β assays. Changes in related pro-apoptosis and anti-apoptosis proteins were detected by Western blot. Optical microscopy showed that GA improved cell morphology, including cell shrinkage, cauliflower-like membrane blebbing, and even some cell debris. Meanwhile, GA also ameliorated cell nuclei characteristics such as nucleus size, chromatin condensation and bright staining from Hoechst 33342 staining. GA also lowered the apoptotic rate and the levels of LDH, CK-MB and IL-1β in a dose-dependent manner. Furthermore, GA treatment increased Bcl-2 protein expression and decreased caspase-8 and Bax protein expression, while elevating the Bcl-2/Bax ratio. GA preconditioning increased p-AKt protein expression; however, after adding LY 294002, the p-AKt expression decreased obviously. Our results demonstrated that GA could protect H9c2 cells from apoptosis in a dose-dependent manner, and the potential mechanism might be related to the PI3K/AKt signaling pathway.

LPA/PKD-1-FoxO1 Signaling Axis Mediates Endothelial Cell CD36 Transcriptional Repression and Proangiogenic and Proarteriogenic Reprogramming

OBJECTIVE

CD36 is a scavenger and antiangiogenic receptor that is important in atherothrombotic diseases, diabetes mellitus, cancer, and obesity. Lysophosphatidic acid, a phospholipid signaling mediator, abolishes endothelial cell responses to antiangiogenic proteins containing thrombospondin type 1 homology domains by downregulating endothelial CD36 transcription via protein kinase D1 (PKD-1) signaling. We aimed to understand mechanisms by which lysophosphatidic acid-mediated angiogenic signaling is integrated to regulate CD36 transcription and endothelial cell function via a nuclear transcriptional complex.

APPROACH AND RESULTS

Microvascular endothelial cells expressing CD36 were used for studying angiogenic signaling and CD36 transcription. Gene transfection and transduction, RT-qPCR, avidin-biotin-conjugated DNA-binding assay, chromatin immunoprecipitation assay, co-immunoprecipitation, proximal ligation assay, and immunofluorescence microscopy showed that lysophosphatidic acid-mediated CD36 transcriptional repression involved PKD-1 signaling mediated formation of forkhead box protein O1-histone deacetylase 7 complex in the nucleus. Unexpectedly, turning off CD36 transcription initiated reprogramming microvascular endothelial cells to express ephrin B2, a critical molecular signature involved in angiogenesis and arteriogenesis. Spheroid-based angiogenesis and in vivo Matrigel angiogenesis assays indicated that angiogenic branching morphogenesis and in vivo angiogenesis were dependent on PKD-1 signaling. A mouse tumor angiogenesis model revealed enhanced PKD-1 signaling and expression of ephrin B2 and smooth muscle actin in neovessels of Lewis Lung Carcinomas, along with low-CD36 expression or CD36 deficiency.

CONCLUSIONS

Lysophosphatidic acid/PKD-1 signaling leads to nuclear accumulation of histone deacetylase 7, where it interacts with forkhead box protein O1 to suppress endothelial CD36 transcription and mediates silencing of antiangiogenic switch, resulting in proangiogenic and proarteriogenic reprogramming. Targeting this signaling cascade could be a novel approach for ischemic cardiovascular disease and cancer.

Transcriptome of the inner circular smooth muscle of the developing mouse intestine: Evidence for regulation of visceral smooth muscle genes by the hedgehog target gene, cJun

BACKGROUND

Digestion is facilitated by coordinated contractions of the intestinal muscularis externa, a bilayered smooth muscle structure that is composed of inner circular muscles (ICM) and outer longitudinal muscles (OLM). We performed transcriptome analysis of intestinal mesenchyme tissue at E14.5, when the ICM, but not the OLM, is present, to investigate the transcriptional program of the ICM.

RESULTS

We identified 3967 genes enriched in E14.5 intestinal mesenchyme. The gene expression profiles were clustered and annotated to known muscle genes, identifying a muscle-enriched subcluster. Using publically available in situ data, 127 genes were verified as expressed in ICM. Examination of the promoter and regulatory regions for these co-expressed genes revealed enrichment for cJUN transcription factor binding sites, and cJUN protein was enriched in ICM. cJUN ChIP-seq, performed at E14.5, revealed that cJUN regulatory regions contain characteristics of muscle enhancers. Finally, we show that cJun is a target of Hedgehog (Hh), a signaling pathway known to be important in smooth muscle development, and identify a cJun genomic enhancer that is responsive to Hh.

CONCLUSIONS

This work provides the first transcriptional catalog for the developing ICM and suggests that cJun regulates gene expression in the ICM downstream of Hh signaling. Developmental Dynamics 245:614-626, 2016. © 2016 Wiley Periodicals, Inc.

Downregulation of Foxc2 enhances apoptosis induced by 5-fluorouracil through activation of MAPK and AKT pathways in colorectal cancer

The chemotherapy drug 5-fluorouracil (5-FU) is fundamental for the treatment of colorectal cancer (CRC); however, drug resistance to 5-FU may occasionally occur. Abnormal expression of Forkhead box C2 gene (Foxc2) has been identified in several human cancers, but the role of Foxc2 in the progression of CRC remains unclear. The present study established a stable Foxc2-short hairpin (sh)RNA cell line, which was confirmed by western blot analysis and quantitative polymerase chain reaction. The Foxc2-shRNA cells were treated with 5-FU and the cell viability was determined by an MTT assay. Western blot analysis was performed to investigate the signaling pathway involved in 5-FU treatment. The present study identified that 5-FU increased the percentage of apoptotic CRC cells among the Foxc2/RNA interference-transfected cells compared with cells transfected with an empty vector. Therefore, the downregulation of Foxc2, induced by 5-FU, may enhance apoptosis by the downregulation of apoptotic factors, including B cell lymphoma-2 and pro-caspase-3, in Foxc2-shRNA CRC cells. Furthermore, the mitogen-activated protein kinase (MAPK) and phosphatidylinositide 3-kinases/protein kinase B (PI3K/AKT) pathways were essential for the sensitization effect of Foxc2 to 5-FU treatment. Overall, these findings reveal the mechanisms behind Foxc2 depletion and 5-FU treatment of CRC and suggest that Foxc2 enhances resistance to apoptosis, induced by 5-FU, through the activation of MAPK and P13K/AKT pathways, and may serve as a valuable clinical prognostic marker for CRC.

Cellular and molecular biology of aging endothelial cells

Cardiovascular disease (CVD) is the leading cause of death in the United States and aging is a major risk factor for CVD development. One of the major age-related arterial phenotypes thought to be responsible for the development of CVD in older adults is endothelial dysfunction. Endothelial function is modulated by traditional CVD risk factors in young adults, but advancing age is independently associated with the development of vascular endothelial dysfunction. This endothelial dysfunction results from a reduction in nitric oxide bioavailability downstream of endothelial oxidative stress and inflammation that can be further modulated by traditional CVD risk factors in older adults. Greater endothelial oxidative stress with aging is a result of augmented production from the intracellular enzymes NADPH oxidase and uncoupled eNOS, as well as from mitochondrial respiration in the absence of appropriate increases in antioxidant defenses as regulated by relevant transcription factors, such as FOXO. Interestingly, it appears that NFkB, a critical inflammatory transcription factor, is sensitive to this age-related endothelial redox change and its activation induces transcription of pro-inflammatory cytokines that can further suppress endothelial function, thus creating a vicious feed-forward cycle. This review will discuss the two macro-mechanistic processes, oxidative stress and inflammation, that contribute to endothelial dysfunction with advancing age as well as the cellular and molecular events that lead to the vicious cycle of inflammation and oxidative stress in the aged endothelium. Other potential mediators of this pro-inflammatory endothelial phenotype are increases in immune or senescent cells in the vasculature. Of note, genomic instability, telomere dysfunction or DNA damage has been shown to trigger cell senescence via the p53/p21 pathway and result in increased inflammatory signaling in arteries from older adults. This review will discuss the current state of knowledge regarding the emerging concepts of senescence and genomic instability as mechanisms underlying oxidative stress and inflammation in the aged endothelium. Lastly, energy sensitive/stress resistance pathways (SIRT-1, AMPK, mTOR) are altered in endothelial cells and/or arteries with aging and these pathways may modulate endothelial function via key oxidative stress and inflammation-related transcription factors. This review will also discuss what is known about the role of "energy sensing" longevity pathways in modulating endothelial function with advancing age. With the growing population of older adults, elucidating the cellular and molecular mechanisms of endothelial dysfunction with age is critical to establishing appropriate and measured strategies to utilize pharmacological and lifestyle interventions aimed at alleviating CVD risk. This article is part of a Special Issue entitled "SI: CV Aging".

Cardioprotective effect of propofol against oxygen glucose deprivation and reperfusion injury in H9c2 cells

BACKGROUND

The intravenous anesthetic propofol is reported to be a cardioprotective agent against ischemic-reperfusion injury in the heart. However, the regulatory mechanism still remains unclear.

METHODS

In this study, we used H9c2 cell line under condition of oxygen glucose deprivation (OGD) followed by reperfusion (OGD/R) to induce in vitro cardiomyocytes ischemia-reperfusion injury. Propofol (5, 10, and 20 μM) was added to the cell cultures before and during the OGD/R phases to investigate the underlying mechanism.

RESULTS

Our data showed that OGD/R decreased cell viability, and increased lactate dehydrogenase leakage, and reactive oxygen species and malondialdehyde production in H9c2 cells, all of which were significantly reversed by propofol. Moreover, we found that propofol increased both the activities and protein expressions of superoxide dismutase and catalase. In addition, propofol increased FoxO1 expression in a dose-dependent manner and inhibited p-AMPK formation significantly.

CONCLUSIONS

These results indicate that the propofol might exert its antioxidative effect through FoxO1 in H9c2 cells, and it has a potential therapeutic effect on cardiac disorders involved in oxidative stress.

The cardioprotection of the insulin-mediated PI3K/Akt/mTOR signaling pathway

Apoptosis occurs frequently in myocardial infarction, oxidative stress injury, and ischemia/reperfusion injury, and plays a pivotal role in the development of heart diseases. Inhibition of apoptosis alone does not necessarily lead to meaningful rescue in terms of either cardiomyocyte survival or function. Activation of the PI3K/Akt signaling pathway induced by insulin not only inhibits cardiomyocyte apoptosis but also substantially preserves and even improves regional and overall cardiac function. Insulin can protect cardiomyocytes from apoptosis by regulating a number of signaling molecules, such as eNOS, FOXOs, Bad, GSK-3β, mTOR, NDRG2, and Nrf2, through activating PI3K and Akt. This review focuses on the protective mechanisms and targets of insulin identified in the prevention and treatment of myocardial injury.