Regulation of endothelial cell cytoskeletal reorganization by a secreted frizzled-related protein-1 and frizzled 4- and frizzled 7-dependent pathway: role in neovessel formation

Deciphering potential vascularization factors of on-chip co-cultured hiPSC-derived cerebral organoids

The lack of functional vascular system in stem cell-derived cerebral organoids (COs) limits their utility in modeling developmental processes and disease pathologies. Unlike other organs, brain vascularization is poorly understood, which makes it particularly difficult to mimic in vitro. Although several attempts have been made to vascularize COs, complete vascularization leading to functional capillary network development has only been achieved via transplantation into a mouse brain. Understanding the cues governing neurovascular communication is therefore imperative for establishing an efficient in vitro system for vascularized cerebral organoids that can emulate human brain development. Here, we used a multidisciplinary approach combining microfluidics, organoids, and transcriptomics to identify molecular changes in angiogenic programs that impede the successful in vitro vascularization of human induced pluripotent stem cell (iPSC)-derived COs. First, we established a microfluidic cerebral organoid (CO)-vascular bed (VB) co-culture system and conducted transcriptome analysis on the outermost cell layer of COs cultured on the preformed VB. Results revealed coordinated regulation of multiple pro-angiogenic factors and their downstream targets. The VEGF-HIF1A-AKT network was identified as a central pathway involved in the angiogenic response of cerebral organoids to the preformed VB. Among the 324 regulated genes associated with angiogenesis, six transcripts represented significantly regulated growth factors with the capacity to influence angiogenic activity during co-culture. Subsequent on-chip experiments demonstrated the angiogenic and vasculogenic potential of cysteine-rich angiogenic inducer 61 (CYR61) and hepatoma-derived growth factor (HDGF) as potential enhancers of organoid vascularization. Our study provides the first global analysis of cerebral organoid response to three-dimensional microvasculature for in vitro vascularization.

Expression of secreted frizzled-related proteins in acute aortic dissection patients and the effects on prognosis

Background

Secreted frizzled-related proteins (SFRPs) were reported to be involved in cardiovascular diseases. This study aimed to observe plasma SFRP levels in acute aortic dissection (AD) patients and the effects of SFRP expression on AD prognosis.

Methods

Plasma levels of SFRP1, SFRP2, SFRP3, SFRP4, and SFRP5 were measured in AD patients and non-AD (NAD) patients. The end-point events information of AD patients, including all-cause death and various clinical complications due to aortic dissection, was collected during a 36-month follow-up.

Results

The SFRP1, SFRP2, SFRP3, and SFRP4 levels were increased in AD patients compared with those in NAD patients, while the SFRP5 concentrations were decreased. No differences in any of the SFRP levels were observed between the type A group and the type B group. The AD patients with end-point events exhibited higher SFRP1, SFRP2, SFRP3, and SFRP4 concentrations but lower SFRP5 levels than the patients without end-point events. In addition, the AD patients were divided into a high group and a low group based on the median SFRP levels, and Kaplan-Meier analysis revealed that the AD patients with high SFRP1, SFRP2, SFRP4, or SFRP5 levels had a better prognosis than those with low levels. However, the AD patients with high SFRP3 levels exhibited the opposite trends. The binary logistic regression analysis found that SFRP1, SFRP2, SFRP4, and SFRP5 were all negatively correlated with the occurrence of end-point events, while SFRP3 was positively correlated with its occurrence.

Conclusions

SFRP levels are all changed in acute AD, which may affect the prognosis of AD patients. SFRPs may be a target to improve the prognosis of AD.

Oscillatory shear stress-induced downregulation of TET1s injures vascular endothelial planar cell polarity by suppression of actin polymerization

Vascular endothelial polarity induced by blood flow plays crucial roles in the development of atherosclerosis. Loss of endothelial polarity leads to an increase in permeability and leukocyte recruitment, which are crucial hallmarks of atherosclerotic initiation. Endothelial cells exhibit a morphological adaptation to hemodynamic shear stress and possesses planar cell polarity to the direction of blood flow. However, the mechanism of how hemodynamic shear stress regulates endothelial planar cell polarity has not been firmly established. Here, we found that TET1s, a short isoform of Tet methylcytosine dioxygenase 1, was a mediator in the regulation of the planar cell polarity in endothelial cells in response to hemodynamic shear stress. In the process, low expression of TET1s induced by oscillatory shear stress led to the endothelial planar polarity damage through inhibition of F-actin polymerization. TET1s can regulate demethylation level of the sFRP-1 promoter to alter the expression of sFRP-1, which affects the interaction of sFRP-1/Fzd4 and F-actin polymerization. Our study revealed the mechanism of how TET1s mediates endothelial planar cell polarity in response to hemodynamic shear stress and provides a new insight for the prevention of atherosclerosis.

SGLT2 inhibitor ameliorates endothelial dysfunction associated with the common ALDH2 alcohol flushing variant

The common aldehyde dehydrogenase 2 (ALDH2) alcohol flushing variant known as ALDH2*2 affects ∼8% of the world's population. Even in heterozygous carriers, this missense variant leads to a severe loss of ALDH2 enzymatic activity and has been linked to an increased risk of coronary artery disease (CAD). Endothelial cell (EC) dysfunction plays a determining role in all stages of CAD pathogenesis, including early-onset CAD. However, the contribution of ALDH2*2 to EC dysfunction and its relation to CAD are not fully understood. In a large genome-wide association study (GWAS) from Biobank Japan, ALDH2*2 was found to be one of the strongest single-nucleotide polymorphisms associated with CAD. Clinical assessment of endothelial function showed that human participants carrying ALDH2*2 exhibited impaired vasodilation after light alcohol drinking. Using human induced pluripotent stem cell-derived ECs (iPSC-ECs) and CRISPR-Cas9-corrected ALDH2*2 iPSC-ECs, we modeled ALDH2*2-induced EC dysfunction in vitro, demonstrating an increase in oxidative stress and inflammatory markers and a decrease in nitric oxide (NO) production and tube formation capacity, which was further exacerbated by ethanol exposure. We subsequently found that sodium-glucose cotransporter 2 inhibitors (SGLT2i) such as empagliflozin mitigated ALDH2*2-associated EC dysfunction. Studies in ALDH2*2 knock-in mice further demonstrated that empagliflozin attenuated ALDH2*2-mediated vascular dysfunction in vivo. Mechanistically, empagliflozin inhibited Na⁺/H⁺-exchanger 1 (NHE-1) and activated AKT kinase and endothelial NO synthase (eNOS) pathways to ameliorate ALDH2*2-induced EC dysfunction. Together, our results suggest that ALDH2*2 induces EC dysfunction and that SGLT2i may potentially be used as a preventative measure against CAD for ALDH2*2 carriers.

Expression Profile of Genes Encoding Proteins Involved in Regulation of Vasculature Development and Heart Muscle Morphogenesis-A Transcriptomic Approach Based on a Porcine Model

Despite significant advances in treatment of acute coronary syndromes (ACS) many subjects still develop heart failure due to significantly reduced ejection fraction. Currently, there are no commonly available treatment strategies that replace the infarcted/dysfunctional myocardium. Therefore, understanding the mechanisms that control the regeneration of the heart muscle is important. The development of new coronary vessels plays a pivotal role in cardiac regeneration. Employing microarray expression assays and RT-qPCR validation expression pattern of genes in long-term primary cultured cells isolated form the right atrial appendage (RAA) and right atrium (RA) was evaluated. After using DAVID software, it indicated the analysis expression profiles of genes involved in ontological groups such as: “angiogenesis”, “blood vessel morphogenesis”, “circulatory system development”, “regulation of vasculature development”, and “vasculature development” associated with the process of creation new blood vessels. The performed transcriptomic comparative analysis between two different compartments of the heart muscle allowed us to indicate the presence of differences in the expression of key transcripts depending on the cell source. Increases in culture intervals significantly increased expression of SFRP2, PRRX1 genes and some other genes involved in inflammatory process, such as: CCL2, IL6, and ROBO1. Moreover, the right atrial appendage gene encoding lysyl oxidase (LOX) showed much higher expression compared to the pre-cultivation state.

Functional interplay between long non-coding RNAs and the Wnt signaling cascade in osteosarcoma

Osteosarcoma is a common and highly malignant bone tumor among children, adolescents and young adults. However, the underlying molecular mechanisms remain largely unexplored. LncRNAs are transcripts with no or limited protein-coding capacity in human genomes, and have been demonstrated to play crucial functions in initiation, progression, therapeutic resistance, recurrence and metastasis of tumor. Considerable studies revealed a dysregulated lncRNA expression pattern in osteosarcoma, which may act as oncogenes or suppressors to regulate osteosarcoma progression. Wnt signaling pathway is an important cascade in tumorigenesis by modulation of pleiotropic biological functions including cell proliferation, apoptosis, differentiation, stemness, genetic stability and chemoresistance. Hyperactivation or deficiency of key effectors in Wnt cascade is a common event in many osteosarcoma patients. Recently, increasing evidences have suggested that lncRNAs could interplay with component of Wnt pathway, and thereby contribute to osteosarcoma onset, progression and dissemination. In this review, we briefly summarize Wnt signaling-related lncRNAs in osteosarcoma progression, aiming to gain insights into their underlying crosstalk as well as clinical application in osteosarcoma therapeutic modalities.

Secreted Frizzled Related Proteins in Cardiovascular and Metabolic Diseases

Abnormal gene expression and secreted protein levels are accompanied by extensive pathological changes. Secreted frizzled related protein (SFRP) family members are antagonistic inhibitors of the Wnt signaling pathway, and they were recently found to be involved in the pathogenesis of a variety of metabolic diseases, which has led to extensive interest in SFRPs. Previous reports highlighted the importance of SFRPs in lipid metabolism, obesity, type 2 diabetes mellitus and cardiovascular diseases. In this review, we provide a detailed introduction of SFRPs, including their structural characteristics, receptors, inhibitors, signaling pathways and metabolic disease impacts. In addition to summarizing the pathologies and potential molecular mechanisms associated with SFRPs, this review further suggests the potential future use of SFRPs as disease biomarkers therapeutic targets.

Role of Sfrps in cardiovascular disease

Secreted frizzled-related proteins (Sfrps) are a family of secreted proteins that bind extracellularly to Wnt ligands and frizzled receptors. This binding modulates the Wnt signaling cascade, and Sfrps interact with their corresponding receptors. Sfrps are thought to play an important role in the pathological mechanism of cardiac disease such as myocardial infarction, cardiac remodeling, and heart failure. However, the overall role of Sfrps in cardiac disease is unknown. Some members of the Sfrps family modulate cellular apoptosis, angiogenesis, differentiation, the inflammatory process, and cardiac remodeling. In this review, we summarize the evidence of Sfrps association with cardiac disease. We also discuss how multiple mechanisms may underlie Sfrps being involved in such diverse pathologies.

Therapies targeting Frizzled-7/β-catenin pathway prevent the development of pathological angiogenesis in an ischemic retinopathy model

Retinopathies remain major causes of visual impairment in diabetic patients and premature infants. Introduction of anti-angiogenic drugs targeting vascular endothelial growth factor (VEGF) has transformed therapy for these proliferative retinopathies. However, limitations associated with anti-VEGF medications require to unravel new pathways of vessel growth to identify potential drug targets. Here, we investigated the role of Wnt/Frizzled-7 (Fzd7) pathway in a mouse model of oxygen-induced retinopathy (OIR). Using transgenic mice, which enabled endothelium-specific and time-specific Fzd7 deletion, we demonstrated that Fzd7 controls both vaso-obliteration and neovascular phases (NV). Deletion of Fzd7 at P12, after the ischemic phase of OIR, prevented formation of aberrant neovessels into the vitreous by suppressing proliferation of endothelial cells (EC) in tufts. Next we validated in vitro two Frd7 blocking strategies: a monoclonal antibody (mAbFzd7) against Fzd7 and a soluble Fzd7 receptor (CRD). In vivo a single intravitreal microinjection of mAbFzd7 or CRD significantly attenuated retinal neovascularization (NV) in mice with OIR. Molecular analysis revealed that Fzd7 may act through the activation of Wnt/β-catenin and Jagged1 expression to control EC proliferation in extra-retinal neovessels. We identified Fzd7/β-catenin signaling as new regulator of pathological retinal NV. Fzd7 appears to be a potent pharmacological target to prevent or treat aberrant angiogenesis of ischemic retinopathies.

The Horizontal Raphe of the Human Retina and its Watershed Zones

The horizontal raphe (HR) as a demarcation line dividing the retina and choroid into separate vascular hemispheres is well established, but its development has never been discussed in the context of new findings of the last decades. Although factors for axon guidance are established (e.g., slit-robo pathway, ephrin-protein-receptor pathway) they do not explain HR formation. Early morphological organization, too, fails to establish a HR. The development of the HR is most likely induced by the long posterior ciliary arteries which form a horizontal line prior to retinal organization. The maintenance might then be supported by several biochemical factors. The circulation separate superior and inferior vascular hemispheres communicates across the HR only through their anastomosing capillary beds resulting in watershed zones on either side of the HR. Visual field changes along the HR could clearly be demonstrated in vascular occlusive diseases affecting the optic nerve head, the retina or the choroid. The watershed zone of the HR is ideally protective for central visual acuity in vascular occlusive diseases but can lead to distinct pathological features.

New Insights about the Wnt/β-Catenin Signaling Pathway in Primary Bone Tumors and Their Microenvironment: A Promising Target to Develop Therapeutic Strategies?

Osteosarcoma and Ewing sarcoma are the most common malignant primary bone tumors mainly occurring in children, adolescents and young adults. Current standard therapy includes multidrug chemotherapy and/or radiation specifically for Ewing sarcoma, associated with tumor resection. However, patient survival has not evolved for the past decade and remains closely related to the response of tumor cells to chemotherapy, reaching around 75% at 5 years for patients with localized forms of osteosarcoma or Ewing sarcoma but less than 30% in metastatic diseases and patients resistant to initial chemotherapy. Despite Ewing sarcoma being characterized by specific EWSR1-ETS gene fusions resulting in oncogenic transcription factors, currently, no targeted therapy could be implemented. It seems even more difficult to develop a targeted therapeutic strategy in osteosarcoma which is characterized by high complexity and heterogeneity in genomic alterations. Nevertheless, the common point between these different bone tumors is their ability to deregulate bone homeostasis and remodeling and divert them to their benefit. Therefore, targeting different actors of the bone tumor microenvironment has been hypothesized to develop new therapeutic strategies. In this context, it is well known that the Wnt/β-catenin signaling pathway plays a key role in cancer development, including osteosarcoma and Ewing sarcoma as well as in bone remodeling. Moreover, recent studies highlight the implication of the Wnt/β-catenin pathway in angiogenesis and immuno-surveillance, two key mechanisms involved in metastatic dissemination. This review focuses on the role played by this signaling pathway in the development of primary bone tumors and the modulation of their specific microenvironment.

Dynamic decreased expression and hypermethylation of secreted frizzled-related protein 1 and 4 over the course of pulmonary fibrosis in mice

Aberrantly activated Wnt signaling pathway and dysregulation of extracellular antagonists of Wnt signaling have been revealed in pulmonary fibrosis. In this study we evaluated the expression of secreted frizzled-related proteins (SFRPs) and their aberrant promoter methylation to investigate the involvement of epigenetic regulation in pulmonary fibrosis. The pulmonary fibrosis induced by intratracheal injection of bleomycin (BLM) into mice was adopted. The transcription and relative protein expression of SFRPs were detected at Day 7 (D7), D14, and D21. DNA methylation analysis was performed by methylation-specific polymerase chain reaction (MSP). A DNA methyltransferase (DNMT) inhibitor (5-aza-2'-deoxycytidine; 5-aza) was used for demethylation and the relative β-catenin expression levels were measured to assess overactivity of the canonical Wnt signaling pathway. The transcription and protein expression of SFRP1 significantly decreased at D14 and D21, whereas the transcription and protein expression of SFRP4 significantly decreased at D7 and stayed downregulated until D21. The significantly hypermethylated promoters of SFRP1 and SFRP4 resulted in impaired transcription and decreased expression during pulmonary fibrosis in mice. Besides, reactivation of SFRP1 and SFRP4 by 5-aza reduced β-catenin mRNA and protein expression in vivo and in vitro. Animal experiments confirmed that 5-aza could significantly alleviate bleomycin-induced pulmonary fibrosis in mice. Thus, changes of promoter hypermethylation might downregulate SFRP1 and SFRP4 at different stages of pulmonary fibrosis, and the finding supports the usefulness of DNMT inhibitors, which might effectively reverse activation of β-catenin and reduce pulmonary fibrosis in mice. These data provide a possible new direction in the research on pulmonary fibrosis treatments.

Wnt Signaling in vascular eye diseases

The Wnt signaling pathway plays a pivotal role in vascular morphogenesis in various organs including the eye. Wnt ligands and receptors are key regulators of ocular angiogenesis both during the eye development and in vascular eye diseases. Wnt signaling participates in regulating multiple vascular beds in the eye including regression of the hyaloid vessels, and development of structured layers of vasculature in the retina. Loss-of-function mutations in Wnt signaling components cause rare genetic eye diseases in humans such as Norrie disease, and familial exudative vitreoretinopathy (FEVR) with defective ocular vasculature. On the other hand, experimental studies in more prevalent vascular eye diseases, such as wet age-related macular degeneration (AMD), diabetic retinopathy (DR), retinopathy of prematurity (ROP), and corneal neovascularization, suggest that aberrantly increased Wnt signaling is one of the causations for pathological ocular neovascularization, indicating the potential of modulating Wnt signaling to ameliorate pathological angiogenesis in eye diseases. This review recapitulates the key roles of the Wnt signaling pathway during ocular vascular development and in vascular eye diseases, and pharmaceutical approaches targeting the Wnt signaling as potential treatment options.

Clinical advantages and disadvantages of anabolic bone therapies targeting the WNT pathway

The WNT signalling pathway is a key regulator of bone metabolism, particularly bone formation, which has helped to define the role of osteocytes - the most abundant bone cells - as orchestrators of bone remodelling. Several molecules involved in the control of the WNT signalling pathway have been identified as potential targets for the development of bone-building therapeutics for patients with osteoporosis. Several of these molecules have been investigated in animal models, but only inhibitors of sclerostin (which is produced by osteocytes) have been investigated in phase III clinical studies. Here, we review the rationale for these developments and the specificity and potential off-target actions of WNT-based therapeutics. We also describe the available preclinical and clinical studies and discuss the benefits and risks of using sclerostin inhibitors for the management of patients with osteoporosis.

miR-539-5p inhibits experimental choroidal neovascularization by targeting CXCR7

Stromal cell-derived factor-1 (SDF-1) has been previously confirmed to participate in the formation of choroidal neovascularization (CNV) via its receptor, CXC chemokine receptor (CXCR) 4; CXCR7 is a recently identified receptor for SDF-1. The molecular mechanisms and therapeutic value of CXCR7 in CNV remain undefined. In this study, experimental CNV was induced by laser photocoagulation in Brown-Norway pigmented rats, and aberrant CXCR7 overexpression was detected in the retinal pigment epithelial/choroid/sclera tissues of laser-injured eyes. Blockade of CXCR7 activation via CXCR7 knockdown or neutralizing Ab administration inhibited SDF-1-induced cell survival and the tubular formation of human retinal microvascular endothelial cells (HRMECs) in vitro and reduced CNV leakage and lesion size in vivo. By using microRNA array screening and bioinformatic analyses, we identified miR-539-5p as a regulator of CXCR7. Transfection of HRMECs and choroid-retinal endothelial (RF/6A) cells with the miR-539-5p mimic inhibited their survival and tube formation, whereas CXCR7 overexpression rescued the suppressive effect of miR-539-5p. The antiangiogenic activities of the miR-539-5p mimic were additionally demonstrated in vivo by intravitreal injection. ERK1/2 and AKT signaling downstream of CXCR7 is involved in the miR-539-5p regulation of endothelial cell behaviors. These findings suggest that the manipulation of miR-539-5p/CXCR7 levels may have important therapeutic implications in CNV-associated diseases.-Feng, Y., Wang, J., Yuan, Y., Zhang, X., Shen, M., Yuan, F. miR-539-5p inhibits experimental choroidal neovascularization by targeting CXCR7.

Human amnion cells reverse acute and chronic pulmonary damage in experimental neonatal lung injury

Background

Despite advances in neonatal care, bronchopulmonary dysplasia (BPD) remains a significant contributor to infant mortality and morbidity. While human amnion epithelial cells (hAECs) have shown promise in small and large animal models of BPD, there is scarce information on long-term benefit and clinically relevant questions surrounding administration strategy remain unanswered. In assessing the therapeutic potential of hAECs, we investigated the impact of cell dosage, administration routes and timing of treatment in a pre-clinical model of BPD.

Methods

Lipopolysaccharide was introduced intra-amniotically at day 16 of pregnancy prior to exposure to 65% oxygen (hyperoxia) at birth. hAECs were administered either 12 hours (early) or 4 days (late) after hyperoxia commenced. Collective lung tissues were subjected to histological analysis, multikine ELISA for inflammatory cytokines, FACS for immune cell populations and 3D lung stem cell culture at neonatal stage (postnatal day 7 and 14). Invasive lung function test and echocardiography were applied at 6 and 10 weeks of age.

Results

hAECs improved the tissue-to-airspace ratio and septal crest density in a dose-dependent manner, regardless of administration route. Early administration of hAECs, coinciding with the commencement of postnatal hyperoxia, was associated with reduced macrophages, dendritic cells and natural killer cells. This was not the case if hAECs were administered when lung injury was established. Fittingly, early hAEC treatment was more efficacious in reducing interleukin-1β, tumour necrosis factor alpha and monocyte chemoattractant protein-1 levels. Early hAEC treatment was also associated with reduced airway hyper-responsiveness and normalisation of pressure–volume loops. Pulmonary hypertension and right ventricle hypertrophy were also prevented in the early hAEC treatment group, and this persisted until 10 weeks of age.

Conclusions

Early hAEC treatment appears to be advantageous over late treatment. There was no difference in efficacy between intravenous and intratracheal administration. The benefits of hAEC administration resulted in long-term improvements in cardiorespiratory function.

Electronic supplementary material

The online version of this article (doi:10.1186/s13287-017-0689-9) contains supplementary material, which is available to authorized users.

The Role of Wnt Signalling in Angiogenesis

Angiogenesis is a normal biological process wherein new blood vessels form from the growth of pre-existing blood vessels. Preventing angiogenesis in solid tumours by targeting pro-angiogenic factors including vascular endothelial growth factor (VEGF), angiopoietin-1 (Ang-1), basic fibroblast growth factor (bFGF), hepatocyte growth factor, and platelet-derived growth factor (PDGF) is currently under investigation for cancer treatment. Concurrently targeting the cell signalling pathways involved in the transcriptional and post-translational regulation of these factors may provide positive therapeutic results. One such pathway is the Wnt signalling pathway. Wnt was first discovered in mice infected with mouse mammary tumour virus, and has been crucial in improving our understanding of oncogenesis and development. In this review, we summarise molecular and cellular aspects of the importance of Wnt signalling to angiogenesis, including β-catenin-dependent mechanisms of angiogenic promotion, as well as the study of Wnt antagonists, such as the secreted frizzled-related protein family (SFRPs) which have been shown to inhibit angiogenesis. The growing understanding of the underlying complexity of the biochemical pathways mediating angiogenesis is critical to the identification of new molecular targets for therapeutic applications.

Breast Cancer Stem-Like Cells Are Inhibited by Diosgenin, a Steroidal Saponin, by the Attenuation of the Wnt β-Catenin Signaling via the Wnt Antagonist Secreted Frizzled Related Protein-4

Background: Identification of breast cancer stem cells as the chemo-resistant and tumor-initiating population represents an important milestone in approaching anticancer therapies. Targeting this minor subpopulation of chemo- and radio-resistant stem-like cells, termed as the cancer stem cells (CSCs) and their eradication could significantly enhance clinical outcomes. Most of the presently administered chemotherapeutics target the tumor bulk but are ineffective against the CSCs. We report here that diosgenin (DG), a naturally occurring steroidal saponin, could effectively inhibit CSCs from three breast cancer cell lines, MCF7, T47D and MDA-MB-231, by inducing apoptosis and inhibiting the CSC associated phenotypes.

Methods: CSCs were enriched in these cells lines, characterized for CSC traits by immunocytochemistry and flow cytometry. Proliferation and apoptosis assays were performed in these breast CSCs in the presence of DG to obtain the inhibitory concentration. Apoptosis was confirmed with gene expression analysis, Western blotting and propidium iodide staining. TCF-LEF reporter assay, sFRP overexpression and RNAi silencing studies were performed to study regulation of the Wnt pathway. Statistical significance was evaluated by a two-sided Student’s t-test.

Results: Using the TCF-LEF reporter system, we show the effect of DG on CSCs is predominantly through the network regulating CSC self renewal, the Wnt β-catenin pathway. Specifically, the Wnt antagonist, the secreted frizzled related protein 4, (sFRP4), had a defining role in the action of DG. Gain-of-function of sFRP4 in CSCs could improve the response to DG wherein CSC mediators were inhibited, β-catenin was down regulated and the effectors of epithelial to mesenchymal transition and pro-invasive markers were repressed. Conversely, the loss-of-function of sFRP4 had a reverse effect on the CSC population which therein became enriched, their response to DG treatment was modest, β-catenin levels increased, GSK3β expression decreased and the expression of epithelial markers of CSC was completely abrogated.

Conclusion: These findings demonstrate the effect of DG on inhibiting the resilient breast CSCs which could provide a benchmark for the development of DG-based therapies in breast cancer treatment.

Plasma protein profiling in patients undergoing coronary artery bypass grafting surgery and clinical significance

This study was designed to identify the protein profiling in patients with triple vessel coronary artery disease (CAD) undergoing CABG, in order to detect CAD-related differential proteins in these patients. CABG patients with triple vessel disease with/without left main stenosis (n =160) were compared to normal coronary angiographic subjects (n =160). Plasma samples of 20 males and 20 females in each group were analyzed with iTRAQ technique. ELISA test was used to test the chosen proteins from iTRAQ results in plasma samples from a new cohort of the CABG group (n=120, male/femal=61/59) and control (n =120, male/female=60/60). iTRAQ detected 544 proteins with 35 up-regulated and 41 down-regulated (change fold > 1.2 or < 0.83, p < 0.05). Three proteins including platelet factor 4 (PF4), coagulation factor XIII B chain (F13B), and secreted frizzled-related protein 1 (sFRP1) were selected for validation by using ELISA that demonstrated significant up-regulation of PF4 and sFRP1 (p < 0.05). There was a positive correlation between these proteins and CAD (p < 0.05) and myocardial infarction history (p < 0.05). Thus, we for the first time have found 76 proteins differentially expressed in plasma of CABG patients. The thrombotic disease/inflammation progress-related protein PF4 and sFRP1, a member of the Wnt/fz signal-transduction pathway and related to myocardial repair, are significantly up-regulated in triple-vessel disease with/without left main stenosis. PF4 may be developed as a biomarker for the diagnosis of the severity of CAD requiring CABG procedure.

Planar cell polarity genes frizzled4 and frizzled6 exert patterning influence on arterial vessel morphogenesis

Quantitative analysis of the vascular network anatomy is critical for the understanding of the vasculature structure and function. In this study, we have combined microcomputed tomography (microCT) and computational analysis to provide quantitative three-dimensional geometrical and topological characterization of the normal kidney vasculature, and to investigate how 2 core genes of the Wnt/planar cell polarity, Frizzled4 and Frizzled6, affect vascular network morphogenesis. Experiments were performed on frizzled4 (Fzd4^-/-) and frizzled6 (Fzd6^-/-) deleted mice and littermate controls (WT) perfused with a contrast medium after euthanasia and exsanguination. The kidneys were scanned with a high-resolution (16 μm) microCT imaging system, followed by 3D reconstruction of the arterial vasculature. Computational treatment includes decomposition of 3D networks based on Diameter-Defined Strahler Order (DDSO). We have calculated quantitative (i) Global scale parameters, such as the volume of the vasculature and its fractal dimension (ii) Structural parameters depending on the DDSO hierarchical levels such as hierarchical ordering, diameter, length and branching angles of the vessel segments, and (iii) Functional parameters such as estimated resistance to blood flow alongside the vascular tree and average density of terminal arterioles. In normal kidneys, fractal dimension was 2.07±0.11 (n = 7), and was significantly lower in Fzd4^-/- (1.71±0.04; n = 4), and Fzd6^-/- (1.54±0.09; n = 3) kidneys. The DDSO number was 5 in WT and Fzd4^-/-, and only 4 in Fzd6^-/-. Scaling characteristics such as diameter and length of vessel segments were altered in mutants, whereas bifurcation angles were not different from WT. Fzd4 and Fzd6 deletion increased vessel resistance, calculated using the Hagen-Poiseuille equation, for each DDSO, and decreased the density and the homogeneity of the distal vessel segments. Our results show that our methodology is suitable for 3D quantitative characterization of vascular networks, and that Fzd4 and Fzd6 genes have a deep patterning effect on arterial vessel morphogenesis that may determine its functional efficiency.

Functional and prognostic significance of the genomic amplification of frizzled 6 (FZD6) in breast cancer

Frizzled receptors mediate Wnt ligand signalling, which is crucially involved in regulating tissue development and differentiation, and is often deregulated in cancer. In this study, we found that the gene encoding the Wnt receptor frizzled 6 (FZD6) is frequently amplified in breast cancer, with an increased incidence in the triple‐negative breast cancer (TNBC) subtype. Ablation of FZD6 expression in mammary cancer cell lines: (1) inhibited motility and invasion; (2) induced a more symmetrical shape of organoid three‐dimensional cultures; and (3) inhibited bone and liver metastasis in vivo. Mechanistically, FZD6 signalling is required for the assembly of the fibronectin matrix, interfering with the organization of the actin cytoskeleton. Ectopic delivery of fibronectin in FZD6‐depleted, triple‐negative MDA‐MB‐231 cells rearranged the actin cytoskeleton and restored epidermal growth factor‐mediated invasion. In patients with localized, lymph node‐negative (early) breast cancer, positivity of tumour cells for FZD6 protein identified patients with reduced distant relapse‐free survival. Multivariate analysis indicated an independent prognostic significance of FZD6 expression in TNBC tumours, predicting distant, but not local, relapse. We conclude that the FZD6–fibronectin actin axis identified in our study could be exploited for drug development in highly metastatic forms of breast cancer, such as TNBC. © 2016 The Authors. The Journal of Pathology published by John Wiley & Sons Ltd on behalf of Pathological Society of Great Britain and Ireland.

Frizzled7: A Promising Achilles' Heel for Targeting the Wnt Receptor Complex to Treat Cancer

Frizzled7 is arguably the most studied member of the Frizzled family, which are the cognate Wnt receptors. Frizzled7 is highly conserved through evolution, from Hydra through to humans, and is expressed in diverse organisms, tissues and human disease contexts. Frizzled receptors can homo- or hetero-polymerise and associate with several co-receptors to transmit Wnt signalling. Notably, Frizzled7 can transmit signalling via multiple Wnt transduction pathways and bind to several different Wnt ligands, Frizzled receptors and co-receptors. These promiscuous binding and functional properties are thought to underlie the pivotal role Frizzled7 plays in embryonic developmental and stem cell function. Recent studies have identified that Frizzled7 is upregulated in diverse human cancers, and promotes proliferation, progression and invasion, and orchestrates cellular transitions that underscore cancer metastasis. Importantly, Frizzled7 is able to regulate Wnt signalling activity even in cancer cells which have mutations to down-stream signal transducers. In this review we discuss the various aspects of Frizzled7 signalling and function, and the implications these have for therapeutic targeting of Frizzled7 in cancer.

An anterior signaling center patterns and sizes the anterior neuroectoderm of the sea urchin embryo

Anterior signaling centers help specify and pattern the early anterior neuroectoderm (ANE) in many deuterostomes. In sea urchin the ANE is restricted to the anterior of the late blastula stage embryo, where it forms a simple neural territory comprising several types of neurons as well as the apical tuft. Here, we show that during early development, the sea urchin ANE territory separates into inner and outer regulatory domains that express the cardinal ANE transcriptional regulators FoxQ2 and Six3, respectively. FoxQ2 drives this patterning process, which is required to eliminate six3 expression from the inner domain and activate the expression of Dkk3 and sFRP1/5, two secreted Wnt modulators. Dkk3 and low expression levels of sFRP1/5 act additively to potentiate the Wnt/JNK signaling pathway governing the positioning of the ANE territory around the anterior pole, whereas high expression levels of sFRP1/5 antagonize Wnt/JNK signaling. sFRP1/5 and Dkk3 levels are rigidly maintained via autorepressive and cross-repressive interactions with Wnt signaling components and additional ANE transcription factors. Together, these data support a model in which FoxQ2 initiates an anterior patterning center that implements correct size and positions of ANE structures. Comparisons of functional and expression studies in sea urchin, hemichordate and chordate embryos reveal striking similarities among deuterostome ANE regulatory networks and the molecular mechanism that positions and defines ANE borders. These data strongly support the idea that the sea urchin embryo uses an ancient anterior patterning system that was present in the common ambulacrarian/chordate ancestor.

Cellular and molecular characterization of human cardiac stem cells reveals key features essential for their function and safety

Cell therapy of heart diseases is emerging as one of the most promising known treatments in recent years. Transplantation of cardiac stem cells (CSCs) may be one of the best strategies to cure adult or pediatric heart diseases. As these patient-derived stem cells need to be isolated from small heart biopsies, it is important to select the best isolation method and CSC subpopulation with the best cardiogenic functionality. We employed three different protocols including c-KIT(+) cell sorting, clonogenic expansion, and explants culture to isolate c-KIT(+) cells, clonogenic expansion-derived cells (CEDCs), and cardiosphere-derived cells (CDCs), respectively. Evaluation of isolated CSC characteristics in vitro and after rat myocardial infarction (MI) model transplantation revealed that although c-KIT(+) and CDCs had higher MI regenerative potential, CEDCs had more commitment into cardiomyocytes and needed lower passages that were essential to reach a definite cell count. Furthermore, genome-wide expression analysis showed that subsequent passages caused changes in characteristics of cells, downregulation of cell cycle-related genes, and upregulation of differentiation and carcinogenic genes, which might lead to senescence, commitment, and possible tumorigenicity of the cells. Because of different properties of CSC subpopulations, we suggest that appropriate CSCs subpopulation should be chosen based on their experimental or clinical use.

Induction of CXC chemokines in human mesenchymal stem cells by stimulation with secreted frizzled-related proteins through non-canonical Wnt signaling

AIM: To investigate the effect of secreted frizzled-related proteins (sFRPs) on CXC chemokine expression in human mesenchymal stem cells (hMSCs).

METHODS: CXC chemokines such as CXCL5 and CXCL8 are induced in hMSCs during differentiation with osteogenic differentiation medium (OGM) and may be involved in angiogenic stimulation during bone repair. hMSCs were treated with conditioned medium (CM) from L-cells expressing non-canonical Wnt5a protein, or with control CM from wild type L-cells, or directly with sFRPs for up to 10 d in culture. mRNA expression levels of both CXCL5 and CXCL8 were quantitated by real-time reverse transcriptase-polymerase chain reaction and secreted protein levels of these proteins determined by ELISA. Dose- (0-500 ng/mL) and time-response curves were generated for treatment with sFRP1. Signal transduction pathways were explored by western blot analysis with pan- or phosphorylation-specific antibodies, through use of specific pathway inhibitors, and through use of siRNAs targeting specific frizzled receptors (Fzd)-2 and 5 or the receptor tyrosine kinase-like orphan receptor-2 (RoR2) prior to treatment with sFRPs.

RESULTS: CM from L-cells expressing Wnt5a, a non-canonical Wnt, stimulated an increase in CXCL5 mRNA expression and protein secretion in comparison to control L-cell CM. sFRP1, which should inhibit both canonical and non-canonical Wnt signaling, surprisingly enhanced the expression of CXCL5 at 7 and 10 d. Dickkopf1, an inhibitor of canonical Wnt signaling prevented the sFRP-stimulated induction of CXCL5 and actually inhibited basal levels of CXCL5 expression at 7 but not at 10 d post treatment. In addition, all four sFRPs isoforms induced CXCL8 expression in a dose- and time-dependent manner with maximum expression at 7 d with treatment at 150 ng/mL. The largest increases in CXCL5 expression were seen from stimulation with sFRP1 or sFRP2. Analysis of mitogen-activated protein kinase signaling pathways in the presence of OGM showed sFRP1-induced phosphorylation of extracellular signal-regulated kinase (ERK) (p44/42) maximally at 5 min after sFRP1 addition, earlier than that found in OGM alone. Addition of a phospholipase C (PLC) inhibitor also prevented sFRP-stimulated increases in CXCL8 mRNA. siRNA technology targeting the Fzd-2 and 5 and the non-canonical Fzd co-receptor RoR2 also significantly decreased sFRP1/2-stimulated CXCL8 mRNA levels.

CONCLUSION: CXC chemokine expression in hMSCs is controlled in part by sFRPs signaling through non-canonical Wnt involving Fzd2/5 and the ERK and PLC pathways.

Frizzled7 controls vascular permeability through the Wnt-canonical pathway and cross-talk with endothelial cell junction complexes

AIMS

Vascular permeability is essential for the health of normal tissues and is an important characteristic of many disease states. The role of the Wnt/frizzled pathway in vascular biology has recently been reported. The objectives of this study are to analyse the role of Frizzled7 (Fzd7) receptor in the control of vascular integrity.

METHODS AND RESULTS

Fzd7 is expressed in endothelial cells and accumulates at the points of cell-cell contact in association with VE-cadherin and β-catenin, two major adherens junction molecules. To selectively delete fzd7 in the vasculature, we developed gene targeting approaches using CreLox strategy in mice. Genetic fzd7 inhibition in the endothelium increases vascular permeability in basal and factor-induced conditions. On the cellular level, fzd7 knockdown or depletion leads to an increase in paracellular permeability with a loss of adherens junction organization. These impairments are associated with a decrease in both VE-Cadherin and β-catenin expression, a decrease in their association and an increase of tyrosine phosphorylation of VE-cadherin/β-catenin. Fzd7 transduces a Wnt/β-catenin signalling cascade that is required to regulate β-catenin and canonical target gene expression. Finally, LiCl, a GSK3 inhibitor, and β-catenin overexpression rescued endothelial integrity and adherens junction organization, induced by fzd7 deletion.

CONCLUSION

These findings establish that Fzd7 is a new partner of adherens junctional complex and represents a novel molecular switch for the control of vascular permeability via activation of the Wnt-canonical pathway.

Deregulation of the miRNAs expression in cervical cancer: human papillomavirus implications

MicroRNAs (miRNAs) are a class of small non coding RNAs of 18-25 nucleotides in length. The temporal or short-lived expression of the miRNAs modulates gene expression post transcriptionally. Studies have revealed that miRNAs deregulation correlates and is involved with the initiation and progression of human tumors. Cervical cancer (CC) displays notably increased or decreased expression of a large number of cellular oncogenic or tumor suppressive miRNAs, respectively. However, understanding the potential role of miRNAs in CC is still limited. In CC, the high-risk human papillomaviruses (HR-HPVs) infection can affect the miRNAs expression through oncoprotein E6 and E7 that contribute to viral pathogenesis, although other viral proteins might also be involved. This deregulation in the miRNAs expression has an important role in the hallmarks of CC. Interestingly, the miRNA expression profile in CC can discriminate between normal and tumor tissue and the extraordinary stability of miRNAs makes it suitable to serve as diagnostic and prognostic biomarkers of cancer. In this review, we will summarize the role of the HR-HPVs in miRNA expression, the role of miRNAs in the hallmarks of CC, and the use of miRNAs as potential prognostic biomarkers in CC.

Attenuation of chondrogenic transformation in vascular smooth muscle by dietary quercetin in the MGP-deficient mouse model

RATIONALE

Cartilaginous metaplasia of vascular smooth muscle (VSM) is characteristic for arterial calcification in diabetes and uremia and in the background of genetic alterations in matrix Gla protein (MGP). A better understanding of the molecular details of this process is critical for the development of novel therapeutic approaches to VSM transformation and arterial calcification.

OBJECTIVE

This study aimed to identify the effects of bioflavonoid quercetin on chondrogenic transformation and calcification of VSM in the MGP-null mouse model and upon TGF-β3 stimulation in vitro, and to characterize the associated alterations in cell signaling.

METHODS AND RESULTS

Molecular analysis revealed activation of β-catenin signaling in cartilaginous metaplasia in Mgp-/- aortae in vivo and during chondrogenic transformation of VSMCs in vitro. Quercetin intercepted chondrogenic transformation of VSM and blocked activation of β-catenin both in vivo and in vitro. Although dietary quercetin drastically attenuated calcifying cartilaginous metaplasia in Mgp-/- animals, approximately one-half of total vascular calcium mineral remained as depositions along elastic lamellae.

CONCLUSION

Quercetin is potent in preventing VSM chondrogenic transformation caused by diverse stimuli. Combined with the demonstrated efficiency of dietary quercetin in preventing ectopic chondrogenesis in the MGP-null vasculature, these findings indicate a potentially broad therapeutic applicability of this safe for human consumption bioflavonoid in the therapy of cardiovascular conditions linked to cartilaginous metaplasia of VSM. Elastocalcinosis is a major component of MGP-null vascular disease and is controlled by a mechanism different from chondrogenic transformation of VSM and not sensitive to quercetin.

Biphasic functional regulation in hippocampus of rat with chronic cerebral hypoperfusion induced by permanent occlusion of bilateral common carotid artery

Background

Chronic cerebral hypoperfusion induced by permanent occlusion of the bilateral common carotid artery (BCCAO) in rats has been commonly used for the study of Alzheimer’s disease and vascular dementia. Despite the apparent cognitive dysfunction in rats with BCCAO, the molecular markers or pathways involved in the pathological alternation have not been clearly identified.

Methods

Temporal changes (sham, 21, 35, 45, 55 and 70 days) in gene expression in the hippocampus of rats after BCCAO were measured using time-course microarray analysis. Gene Ontology (GO) and pathway analyses were performed to identify the functional involvement of temporally regulated genes in BCCAO.

Results

Two major gene expression patterns were observed in the hippocampus of rats after BCCAO. One pattern, which was composed of 341 early up-regulated genes after the surgical procedure, was dominantly involved in immune-related biological functions (false discovery rate [FDR]<0.01). Another pattern composed of 182 temporally delayed down-regulated genes was involved in sensory perception such as olfactory and cognition functions (FDR<0.01). In addition to the two gene expression patterns, the temporal change of GO and the pathway activities using all differentially expressed genes also confirmed that an immune response was the main early change, whereas sensory functions were delayed responses. Moreover, we identified FADD and SOCS3 as possible core genes in the sensory function loss process using text-based mining and interaction network analysis.

Conclusions

The biphasic regulatory mechanism first reported here could provide molecular evidence of BCCAO-induced impaired memory in rats as well as mechanism of the development of vascular dementia.

Pluripotent stem cell-engineered cell sheets reassembled with defined cardiovascular populations ameliorate reduction in infarct heart function through cardiomyocyte-mediated neovascularization

Although stem cell therapy is a promising strategy for cardiac restoration, the heterogeneity of transplanted cells has been hampering the precise understanding of the cellular and molecular mechanisms. Previously, we established a cardiovascular cell differentiation system from mouse pluripotent stem cells, in which cardiomyocytes (CMs), endothelial cells (ECs), and mural cells (MCs) can be systematically induced and purified. Combining this with cell sheet technology, we generated cardiac tissue sheets reassembled with defined cardiovascular populations. Here, we show the potentials and mechanisms of cardiac tissue sheet transplantation in cardiac function after myocardial infarction (MI). Transplantation of the cardiac tissue sheet to a rat MI model showed significant and sustained improvement of systolic function accompanied by neovascularization. Reduction of the infarct wall thinning and fibrotic length indicated the attenuation of left ventricular remodeling. Cell tracing with species-specific fluorescent in situ hybridization after transplantation revealed a relatively early loss of transplanted cells and an increase in endogenous neovascularization in the proximity of the graft, suggesting an indirect angiogenic effect of cardiac tissue sheets rather than direct CM contributions. We prospectively dissected the functional mechanisms with cell type-controlled sheet analyses. Sheet CMs were the main source of vascular endothelial growth factor. Transplantation of sheets lacking CMs resulted in the disappearance of neovascularization and subsequent functional improvement, indicating that the beneficial effects of the sheet were achieved by sheet CMs. ECs and MCs enhanced the sheet functions and structural integration. Supplying CMs to ischemic regions with cellular interaction could be a strategic key in future cardiac cell therapy.

The plating of rat scar myofibroblasts on matrigel unmasks a novel phenotype; the self assembly of lumen-like structures

During tissue healing, the primary role of myofibroblasts involves the synthesis and deposition of collagen. However, it has also been reported that selective populations of myofibroblasts can acquire the phenotype and/or differentiate to other cells types. The present study tested the hypothesis that myofibroblasts isolated from the scar of the ischemically damaged rat heart can recapitulate an endothelial cell-like response when plated in a permissive in vitro environment. Scar myofibroblasts, neonatal and adult ventricular fibroblasts express smooth muscle α-actin, collagen α(1) type 1 and a panel of pro-fibrotic and pro-angiogenic peptide growth factor mRNAs. Myofibroblasts plated alone on matrigel led to the self assembly of lumen-like structures whereas neonatal and adult rat ventricular fibroblasts were unresponsive. Myofibroblasts labeled with the fluorescent cell tracker CM-DiI were injected in the viable myocardium of 3-day post-myocardial infarcted Sprague-Dawley rats and sacrificed 7 days later. Injected CM-DiI-labeled myofibroblasts were detected predominantly in the peri-infarct/infarct region, highlighting their migration to the damaged region. However, engrafted myofibroblasts in the peri-infarct/infarct region were unable to adopt an endothelial cell-like phenotype or lead to the de novo formation of CM-DiI-labeled blood vessels. The non-permissive nature of the infarct region may be attributed at least in part to the presence of growth-promoting stimuli as TGF-β and the β-adrenergic agonist isoproterenol inhibited the self assembly of lumen-like structures by myofibroblasts. Thus, when plated in a permissive in vitro environment, scar myofibroblasts can self assemble and form lumen-like structures providing an additional novel phenotype distinguishing this population from normal ventricular fibroblasts.

Synergism and rules from combination of Baicalin, Jasminoidin and Desoxycholic acid in refined Qing Kai Ling for treat ischemic stroke mice model

Refined Qing-Kai-Ling (QKL), a modified Chinese medicine, consists of three main ingredients (Baicalin, Jasminoidin and Desoxycholic acid), plays a synergistic effect on the treatment of the acute stage of ischemic stroke. However, the rules of the combination and synergism are still unknown. Based on the ischemic stroke mice model, all different kinds of combination of Baicalin, Jasminoidin, and Desoxycholic acid were investigated by the methods of neurological examination, microarray, and genomics analysis. As a result, it confirmed that the combination of three drugs offered a better therapeutical effect on ischemic stroke than monotherapy of each drug. Additionally, we used Ingenuity pathway Analysis (IPA) and principal component analysis (PCA) to extract the dominant information of expression changes in 373 ischemia-related genes. The results suggested that 5 principal components (PC1-5) could account for more than 95% energy in the gene data. Moreover, 3 clusters (PC1, PC2+PC5, and PC3+PC4) were addressed with cluster analysis. Furthermore, we matched PCs on the drug-target networks, the findings demonstrated that Baicalin related with PC1 that played the leading role in the combination; Jasminoidin related with PC2+PC5 that played a compensatory role; while Desoxycholic acid had the least performance alone which could relate with PC3+PC4 that played a compatible role. These manifestations were accorded with the principle of herbal formulae of Traditional Chinese Medicine (TCM), emperor-minister-adjuvant-courier. In conclusion, we firstly provided scientific evidence to the classic theory of TCM formulae, an initiating holistic viewpoint of combination therapy of TCM. This study also illustrated that PCA might be an applicable method to analyze the complicated data of drug combination.

Epigenetic regulation of cell adhesion and communication by enhancer of zeste homolog 2 in human endothelial cells

The histone methyltransferase enhancer of zeste homolog 2 (Ezh2) mediates trimethylation of lysine 27 in histone 3, which acts as a repressive epigenetic mark. Ezh2 is essential for maintaining pluripotency of stem cells, but information on its role in differentiated cells is sparse. Whole-genome mRNA expression arrays identified 964 genes that were regulated by >2-fold 72 hours after small interfering RNA-mediated silencing of Ezh2 in human umbilical vein endothelial cells. Among them, genes associated with the gene ontology terms cell communication and cell adhesion were significantly overrepresented, suggesting a functional role for Ezh2 in the regulation of angiogenesis. Indeed, adhesion, migration, and tube formation assays revealed significantly altered angiogenic properties of human umbilical vein endothelial cells after silencing of Ezh2. To identify direct target genes of Ezh2, we performed chromatin immunoprecipitation experiments followed by whole-genome promoter arrays (chromatin immunoprecipitation-on-chip) and identified 5585 genes associated with trimethylation of lysine 27 in histone 3. Comparative analysis with our mRNA expression data identified 276 genes that met our criteria for putative Ezh2 target genes, upregulation by >2-fold after Ezh2 silencing and association with trimethylation of lysine 27 in histone 3. Notably, we observed a striking overrepresentation of genes involved in wingless-type mouse mammary tumor virus integration site (WNT) signaling pathways. Epigenetic regulation of several of these genes by Ezh2 was specifically confirmed by polymerase chain reaction analysis of DNA enrichment after chromatin immunoprecipitation using an antibody specific for trimethylation of lysine 27 in histone 3. Combining mRNA expression arrays and chromatin immunoprecipitation-on-chip analysis, we identified 276 Ezh2 target genes in endothelial cells. Ezh2-dependent repression of genes involved in cell adhesion and communication contributes to the regulation of angiogenesis.

Different molecular signatures in magnetic resonance imaging-staged facioscapulohumeral muscular dystrophy muscles

BACKGROUND

Facioscapulohumeral muscular dystrophy (FSHD) is one of the most common muscular dystrophies and is characterized by a non-conventional genetic mechanism activated by pathogenic D4Z4 repeat contractions. By muscle Magnetic Resonance Imaging (MRI) we observed that T2-short tau inversion recovery (T2-STIR) sequences identify two different conditions in which each muscle can be found before the irreversible dystrophic alteration, marked as T1-weighted sequence hyperintensity, takes place. We studied these conditions in order to obtain further information on the molecular mechanisms involved in the selective wasting of single muscles or muscle groups in this disease.

METHODS

Histopathology, gene expression profiling and real time PCR were performed on biopsies from FSHD muscles with different MRI pattern (T1-weighted normal/T2-STIR normal and T1-weighted normal/T2-STIR hyperintense). Data were compared with those from inflammatory myopathies, dysferlinopathies and normal controls. In order to validate obtained results, two additional FSHD samples with different MRI pattern were analyzed.

RESULTS

Myopathic and inflammatory changes characterized T2-STIR hyperintense FSHD muscles, at variance with T2-STIR normal muscles. These two states could be easily distinguished from each other by their transcriptional profile. The comparison between T2-STIR hyperintense FSHD muscles and inflammatory myopathy muscles showed peculiar changes, although many alterations were shared among these conditions.

CONCLUSIONS

At the single muscle level, different stages of the disease correspond to the two MRI patterns. T2-STIR hyperintense FSHD muscles are more similar to inflammatory myopathies than to T2-STIR normal FSHD muscles or other muscular dystrophies, and share with them upregulation of genes involved in innate and adaptive immunity. Our data suggest that selective inflammation, together with perturbation in biological processes such as neoangiogenesis, lipid metabolism and adipokine production, may contribute to the sequential bursts of muscle degeneration that involve individual muscles in an asynchronous manner in this disease.

Secreted frizzled-related protein-1 improves postinfarction scar formation through a modulation of inflammatory response

OBJECTIVE

The inflammatory response after myocardial infarction plays a crucial role in the healing process. Lately, there is accumulating evidence that the Wnt/Frizzled pathway may play a distinct role in inflammation. We have shown that secreted frizzled-related protein-1 (sFRP-1) overexpression reduced postinfarction scar size, and we noticed a decrease in neutrophil infiltration in the ischemic tissue. We aimed to further elucidate the role of sFRP-1 in the postischemic inflammatory process.

METHODS AND RESULTS

We found that in vitro, sFRP-1 was able to block leukocyte activation and cytokine production. We transplanted bone marrow cells (BMCs) from transgenic mice overexpressing sFRP-1 into wild-type recipient mice and compared myocardial healing with that of mice transplanted with wild-type BMCs. These results were compared with those obtained in transgenic mice overexpressing sFRP-1 specifically in endothelial cells or in cardiomyocytes to better understand the spatiotemporal mechanism of the sFRP-1 effect. Our findings indicate that when overexpressed in the BMCs, but not in endothelial cells or cardiomyocytes, sFRP-1 was able to reduce neutrophil infiltration after ischemia, by switching the balance of pro- and antiinflammatory cytokine expression, leading to a reduction in scar formation and better cardiac hemodynamic parameters.

CONCLUSION

sFRP-1 impaired the loop of cytokine amplification and decreased neutrophil activation and recruitment into the scar, without altering the neutrophil properties. These data support the notion that sFRP-1 may be a novel antiinflammatory factor protecting the heart from damage after myocardial infarction.

Frizzled 4 Regulates Arterial Network Organization Through Noncanonical Wnt/Planar Cell Polarity Signaling

Rationale:

A growing body of evidence supports the hypothesis that the Wnt/planar cell polarity (PCP) pathway regulates endothelial cell proliferation and angiogenesis, but the components that mediate this regulation remain elusive.

Objective:

We investigated the involvement of one of the receptors, Frizzled4 (Fzd4), in this process because its role has been implicated in retinal vascular development.

Methods and Results:

We found that loss of fzd4 function in mice results in a striking reduction and impairment of the distal small artery network in the heart and kidney. We report that loss of fzd4 decreases vascular cell proliferation and migration and decreases the ability of the endothelial cells to form tubes. We show that fzd4 deletion induces defects in the expression level of stable acetylated tubulin and in Golgi organization during migration. Deletion of fzd4 favors Wnt noncanonical AP1-dependent signaling, indicating that Fzd4 plays a pivotal role favoring PCP signaling. Our data further demonstrate that Fzd4 is predominantly localized on the top of the plasma membrane, where it preferentially induces Dvl3 relocalization to promote its activation and α-tubulin recruitment during migration. In a pathological mouse angiogenic model, deletion of fzd4 impairs the angiogenic response and leads to the formation of a disorganized arterial network.

Conclusions:

These results suggest that Fzd4 is a major receptor involved in arterial formation and organization through a Wnt/PCP pathway.

Secreted frizzled-related proteins are required for Wnt/β-catenin signalling activation in the vertebrate optic cup

Secreted frizzled-related proteins (Sfrps) are considered Wnt signalling antagonists but recent studies have shown that specific family members enhance Wnt diffusion and thus positively modulate Wnt signalling. Whether this is a general and physiological property of all Sfrps remains unexplored. It is equally unclear whether disruption of Sfrp expression interferes with developmental events mediated by Wnt signalling activation. Here, we have addressed these questions by investigating the functional consequences of Sfrp disruption in the canonical Wnt signalling-dependent specification of the mouse optic cup periphery. We show that compound genetic inactivation of Sfrp1 and Sfrp2 prevents Wnt/β-catenin signalling activation in this structure, which fails to be specified and acquires neural retina characteristics. Consistent with a positive role of Sfrps in signalling activation, Wnt spreading is impaired in the retina of Sfrp1(-/-);Sfrp2(-/-) mice. Conversely, forced expression of Sfrp1 in the wing imaginal disc of Drosophila, the only species in which the endogenous Wnt distribution can be detected, flattens the Wg gradient, suppresses the expression of high-Wg target genes but expands those typically activated by low Wg concentrations. Collectively, these data demonstrate that, in vivo, the levels of Wnt signalling activation strongly depend on the tissue distribution of Sfrps, which should be viewed as multifunctional regulators of Wnt signalling.

Genome-wide functional screening of miR-23b as a pleiotropic modulator suppressing cancer metastasis

miRNA globally deregulates human carcinoma. A critical open question is how many miRNAs functionally participate in cancer development, particularly in metastasis. We systematically evaluate the capability of all known human miRNAs to regulate certain metastasis-relevant cell behaviours. To perform the high-throughput screen of miRNAs, which regulate cell migration, we developed a novel self-assembled cell microarray. Here we show that over 20% of miRNAs have migratory regulation activity in diverse cell types, indicating a general involvement of miRNAs in migratory regulation. MiR-23b, which is downregulated in human colon cancer samples, potently mediates the multiple steps of metastasis, including tumour growth, invasion and angiogenesis in vivo. It regulates a cohort of prometastatic targets, including FZD7 or MAP3k1. These findings provide new insight into the physiological and potential therapeutic importance of miRNAs as a new class of functional modulators.

The advantages and disadvantages of sfrp1 and sfrp2 expression in pathological events

Secreted Frizzled Related Proteins (Sfrps) are a family of secreted proteins that can bind both to Wnt ligands and Frizzled receptors, thereby modulating the Wnt signalling cascades. Recent studies have shown that Sfrps can also interact with Wnt unrelated molecules such as RANKL, a member of the tumor necrosis factor family, Tolloid metalloproteinases or integrin-fibronectin complexes. Alterations in the levels of Sfrp expression have been recently associated with different pathological conditions, including tumor formation and bone and myocardial disorders. Here, we summarise the evidence that relates Sfrps with these diseases and discuss how the proposed multiple Sfrp interactions with Wnt related and unrelated pathways may explain their implication in such diverse pathologies.

Hypoxia preconditioned mesenchymal stem cells improve vascular and skeletal muscle fiber regeneration after ischemia through a Wnt4-dependent pathway

Mesenchymal stem cells (MSC) are multipotent postnatal stem cells, involved in the treatment of ischemic vascular diseases. We investigate the ability of MSC, exposed to short-term hypoxic conditions, to participate in vascular and tissue regeneration in an in vivo model of hindlimb ischemia. Transplantation of hypoxic preconditioned murine MSC (HypMSC) enhanced skeletal muscle regeneration at day 7, improved blood flow and vascular formation compared to injected nonpreconditioned MSC (NormMSC). These observed effects were correlated with an increase in HypMSC engraftment and a putative role in necrotic skeletal muscle fiber clearance. Moreover, HypMSC transplantation resulted in a large increase in Wnt4 (wingless-related MMTV integration site 4) expression and we demonstrate its functional significance on MSC proliferation and migration, endothelial cell (EC) migration, as well as myoblast differentiation. Furthermore, suppression of Wnt4 expression in HypMSC, abrogated the hypoxia-induced vascular regenerative properties of these cells in the mouse hindlimb ischemia model. Our data suggest that hypoxic preconditioning plays a critical role in the functional capabilities of MSC, shifting MSC location in situ to enhance ischemic tissue recovery, facilitating vascular cell mobilization, and skeletal muscle fiber regeneration via a paracrine Wnt-dependent mechanism.

Secreted frizzled-related protein 1 extrinsically regulates cycling activity and maintenance of hematopoietic stem cells

Secreted frizzled-related protein 1 (Sfrp1) is highly expressed by stromal cells maintaining hematopoietic stem cells (HSCs). Sfrp1 loss in stromal cells increases production of hematopoietic progenitors, and in knockout mice, dysregulates hemostasis and increases Flk2- Cd34- Lin- Sca1+ Kit+ (LSK) cell numbers in bone marrow. Also, LSK and multipotent progenitors (MPPs) resided mainly in the G0/G1 phase of cell cycle, with an accompanying decrease in intracellular beta-catenin levels. Gene-expression studies showed a concomitant decrease Ccnd1 and Dkk1 in Cd34- LSK cells and increased expression of Pparg, Hes1, and Runx1 in MPP. Transplantation experiments showed no intrinsic effect of Sfrp1 loss on the number of HSCs or their ability to engraft irradiated recipients. In contrast, serial transplantations of wild-type HSCs into Sfrp1(-/-) mice show a progressive decrease of wild-type LSK and MPP numbers. Our results demonstrate that Sfrp1 is required to maintain HSC homeostasis through extrinsic regulation of beta-catenin.

The Wnt modulator sFRP2 enhances mesenchymal stem cell engraftment, granulation tissue formation and myocardial repair

Cell-based therapies, using multipotent mesenchymal stem cells (MSCs) for organ regeneration, are being pursued for cardiac disease, orthopedic injuries and biomaterial fabrication. The molecular pathways that regulate MSC-mediated regeneration or enhance their therapeutic efficacy are, however, poorly understood. We compared MSCs isolated from MRL/MpJ mice, known to demonstrate enhanced regenerative capacity, to those from C57BL/6 (WT) mice. Compared with WT-MSCs, MRL-MSCs demonstrated increased proliferation, in vivo engraftment, experimental granulation tissue reconstitution, and tissue vascularity in a murine model of repair stimulation. The MRL-MSCs also reduced infarct size and improved function in a murine myocardial infarct model compared with WT-MSCs. Genomic and functional analysis indicated a downregulation of the canonical Wnt pathway in MRL-MSCs characterized by significant up-regulation of specific secreted frizzled-related proteins (sFRPs). Specific knockdown of sFRP2 by shRNA in MRL-MSCs decreased their proliferation and their engraftment in and the vascular density of MRL-MSC-generated experimental granulation tissue. These results led us to generate WT-MSCs overexpressing sFRP2 (sFRP2-MSCs) by retroviral transduction. sFRP2-MSCs maintained their ability for multilineage differentiation in vitro and, when implanted in vivo, recapitulated the MRL phenotype. Peri-infarct intramyocardial injection of sFRP2-MSCs resulted in enhanced engraftment, vascular density, reduced infarct size, and increased cardiac function after myocardial injury in mice. These findings implicate sFRP2 as a key molecule for the biogenesis of a superior regenerative phenotype in MSCs.

Constitutive activation of the Wnt canonical pathway in mantle cell lymphoma

Aberrations of the Wnt canonical pathway (WCP) are known to contribute to the pathogenesis of various types of cancer. We hypothesize that these defects may exist in mantle cell lymphoma (MCL). Both the upstream and downstream aspects of WCP were examined in MCL cell lines and tumors. Using WCP-specific oligonucleotide arrays, we found that MCL highly and consistently expressed Wnt3 and Wnt10. beta-catenin, a transcriptional factor that is a downstream target of WCP, is localized to the nucleus and transcriptionally active in all 3 MCL cell lines examined. By immunohistochemistry, 33 (52%) of 64 MCL tumors showed nuclear localization of beta-catenin, which significantly correlated with the expression of the phosphorylated/inactive form of GSK3beta (p-GSK3beta; P = .011, Fisher). GSK3beta inactivation is directly linked to WCP stimulation, since addition of recombinant sFRP proteins (a naturally occurring decoy for the Wnt receptors) resulted in a significant decrease in p-GSK3beta. Down-regulation of DvL-2 (an upstream signaling protein in WCP) by siRNA or selective inhibition of beta-catenin using quercetin significantly decreased cell growth in MCL cell lines. To conclude, WCP is constitutively activated in a subset of MCL and it appears to promote tumorigenesis in MCL.

Secreted frizzled-related protein-1 enhances mesenchymal stem cell function in angiogenesis and contributes to neovessel maturation

Mesenchymal stem cell (MSC) transplantation offers a great angiogenic opportunity in vascular regenerative medicine. The canonical Wnt/beta-catenin signaling pathway has been demonstrated to play an essential role in stem cell fate. Recently, genetic studies have implicated the Wnt/Frizzled (Fz) molecular pathway, namely Wnt7B and Fz4, in blood growth regulation. Here, we investigated whether MSC could be required in shaping a functional vasculature and whether secreted Frizzled-related protein-1 (sFRP1), a modulator of the Wnt/Fz pathway, could modify MSC capacities, endowing MSC to increase vessel maturation. In the engraftment model, we show that murine bone marrow-derived MSC induced a beneficial vascular effect through a direct cellular contribution to vascular cells. MSC quickly organized into primitive immature vessel tubes connected to host circulation; this organization preceded host endothelial cell (EC) and smooth muscle cell (SMC) recruitment to later form mature neovessel. MSC sustained neovessel organization and maturation. We report here that sFRP1 forced expression enhanced MSC surrounding neovessel, which was correlated with an increase in vessel maturation and functionality. In vitro, sFRP1 strongly increased platelet-derived growth factor-BB (PDGF-BB) expression in MSC and enhanced beta-catenin-dependent cell-cell contacts between MSC themselves and EC or SMC. In vivo, sFRP1 increased their functional integration around neovessels and vessel maturation through a glycogen synthase kinase 3 beta (GSK3beta)-dependent pathway. sFRP1-overexpressing MSC compared with control MSC were well elongated and in a closer contact with the vascular wall, conditions required to achieve an organized mature vessel wall. We propose that genetically modifying MSC to overexpress sFRP1 may be potentially effective in promoting therapeutic angiogenesis/arteriogenesis processes. Disclosure of potential conflicts of interest is found at the end of this article.

Wnt/Frizzled signaling in angiogenesis

The roles of growth factors such as angiopoietin (Ang) and vascular endothelial growth factor (VEGF) in angiogenesis have been known for some time, yet we have just an incipient appreciation for the contribution of Wnts to this process. Cellular proliferation and polarity, apoptosis, branching morphogenesis, inductive processes, and the maintenance of stem cells in an undifferentiated, proliferative state are all regulated by Wnt signaling. The development and maintenance of vascular structures are dependent on all these processes, and their orchestration has, to some extent, been revealed in studies of VEGF and Ang receptors. Recent evidence links the Wnt/Frizzled signaling pathway to proper vascular growth in mammals but our knowledge of Wnt function in the vasculature is rudimentary. Further insight into vascular development and the process of angiogenesis depends on evaluating the function of novel endothelial regulatory pathways such as Wnt/Frizzled signaling.