Etv2-miR-130a-Jarid2 cascade regulates vascular patterning during embryogenesis

miR-130a expression is related to aortic dilation in bicuspid aortic valve children

BACKGROUND

Bicuspid aortic valve disease (BAV) is present in 0.5-2% of the population and can promote aortic dilation, eventually leading to fatal consequences. Although some biomarkers have been proposed in adults, no studies have tested these candidates in children. We aimed to evaluate four miRNAs previously described to be related to BAV disease and aortic dilation in adults in a paediatric cohort.

METHODS

Eighty participants ≤17 years old (4-17; mean 12) were included. From the BAV group, 40% had a dilated aorta (z score >2). RT‒qPCR were performed in plasma samples to quantify miR-122, miR-130a, miR-486, and miR-718 using the delta-delta Ct method. Functional and enrichment analyses of miR-130a were also performed.

RESULTS

miR-130a expression in plasma was found to be significantly lower in BAV patients with a dilated aorta versus nondilated patients (p = 0.008) and healthy TAV controls (p = 0.004). Furthermore, miR-130a expression in plasma was inversely correlated with ascending aorta (r = 0.318, p = 0.004) and aortic root z scores (r = 0.322; p = 0.004). Enrichment analysis showed that miR-130a target genes are related to the TGFβ signalling pathway.

CONCLUSIONS

miR-130a expression in plasma is decreased in aortic-dilated BAV children compared to nondilated BAV children, helping differentiate low- to high-risk patients.

IMPACT

miR-130a expression in plasma is related to aortic dilation in bicuspid aortic valve (BAV) children. To our knowledge, this is the first study that analyses miRNA patterns in bicuspid aortic valve children with aortic dilation. miR-130a expression in plasma could be a biomarker in order to help differentiate low-to high-risk BAV children, which is vitally important for advanced care planning.

MiR-155 promotes compensatory lung growth by inhibiting JARID2 activation of CD34+ endothelial progenitor cells

Bone marrow-derived CD34-positive (CD34+) endothelial progenitor cells (EPCs) has unique functions in the mechanism of compensatory lung growth (CLG). The content of this study is mainly to describe the effect of microRNA (miR)-155 in the mechanisms of EPCs and CLG. Our study found that transfection of miR-155 mimic could promote EPC proliferation, migration and tube formation, while transfection of miR-155 inhibitor had the opposite effect. It was also found that transfection of pc-JARID2 inhibited EPC proliferation, migration and tube formation, while transfection of si-JARID2 had the opposite effect. miR-155 can target and negatively regulate JARID2 expression. Overexpression of JARID2 weakened the promoting effects of miR-155 mimic on EPC proliferation, migration, and tubular formation, while silencing JARID2 weakened the inhibitory effects of miR-155 inhibitors on EPC proliferation, migration, and tubular formation. Transplantation of EPCs transfected with miR-155 mimic into the left lung model effectively increased lung volume, total alveolar number, diaphragm surface area, and lung endothelial cell number, while transplantation of EPCs co-transfected with miR-155 mimic and pc-JARID2 reversed this phenomenon. Overall, we found that miR-155 activates CD34+ EPC by targeting negative regulation of JARID2 and promotes CLG.

SeATAC: a tool for exploring the chromatin landscape and the role of pioneer factors

Assay for Transposase-Accessible Chromatin with sequencing (ATAC-seq) reveals chromatin accessibility across the genome. Currently, no method specifically detects differential chromatin accessibility. Here, SeATAC uses a conditional variational autoencoder model to learn the latent representation of ATAC-seq V-plots and outperforms MACS2 and NucleoATAC on six separate tasks. Applying SeATAC to several pioneer factor-induced differentiation or reprogramming ATAC-seq datasets suggests that induction of these factors not only relaxes the closed chromatin but also decreases chromatin accessibility of 20% to 30% of their target sites. SeATAC is a novel tool to accurately reveal genomic regions with differential chromatin accessibility from ATAC-seq data.

Blastocyst complementation and interspecies chimeras in gene edited pigs

The only curative therapy for many endstage diseases is allograft organ transplantation. Due to the limited supply of donor organs, relatively few patients are recipients of a transplanted organ. Therefore, new strategies are warranted to address this unmet need. Using gene editing technologies, somatic cell nuclear transfer and human induced pluripotent stem cell technologies, interspecies chimeric organs have been pursued with promising results. In this review, we highlight the overall technical strategy, the successful early results and the hurdles that need to be addressed in order for these approaches to produce a successful organ that could be transplanted in patients with endstage diseases.

Mechanisms and strategies to promote cardiac xenotransplantation

End stage heart failure is a terminal disease, and the only curative therapy is orthotopic heart transplantation. Due to limited organ availability, alternative strategies have received intense interest for treatment of patients with advanced heart failure. Recent studies using gene-edited porcine organs suggest that cardiac xenotransplantation may provide a future source of organs. In this review, we highlight the historical milestones for cardiac xenotransplantation and the gene editing strategies designed to overcome immunological barriers, which have culminated in a recent cardiac pig-to-human xenotransplant. We also discuss recent results of studies on the engineering of human-porcine chimeric organs that may provide an alternative and complementary strategy to overcome some of the major immunological barriers to producing a new source of transplantable organs.

Molecular Cloning and Expression Responses of Jarid2b to High-Temperature Treatment in Nile Tilapia (Oreochromis niloticus)

Nile tilapia is a GSD + TE (Genetic Sex Determination + Temperature Effect) fish, and high-temperature treatment during critical thermosensitive periods (TSP) can induce the sex reversal of Nile tilapia genetic females, and brain transcriptomes have revealed the upregulation of Jarid2 (Jumonji and AT-rich domain containing 2) expression after 36 °C high-temperature treatment for 12 days during TSP. It was shown that JARID2 forms a complex with polycomb repressive complex 2 (PRC2) that catalyzed H3K27me3, which was strongly associated with transcriptional repression. In this study, Jarid2b was cloned and characterized in Nile tilapia, which was highly conserved among the analyzed fish species. The expression of Jarid2b was upregulated in the gonad of 21 dpf XX genetic females after 12-day high-temperature treatment and reached a similar level to that of males. Similar responses to high-temperature treatment also appeared in the brain, heart, liver, muscle, eye, and skin tissues. Interestingly, Jarid2b expression was only in response to high-temperature treatment, and not to 17α-methyltestosterone (MT) or letrozole treatments; although, these treatments can also induce the sex reversal of genetic Nile tilapia females. Further studies revealed that Jarid2b responded rapidly at the 8th hour after high-temperature treatment. Considering that JARID2 can recruit PRC2 and establish H3K27me3, we speculated that it might be an upstream gene participating in the regulation of Nile tilapia GSD + TE through regulating the H3K27 methylation level at the locus of many sex differentiation-related genes.

The regulatory role of pioneer factors during cardiovascular lineage specification – A mini review

Cardiovascular disease (CVD) remains the number one cause of death worldwide. Ischemic heart disease contributes to heart failure and has considerable morbidity and mortality. Therefore, alternative therapeutic strategies are urgently needed. One class of epigenetic regulators known as pioneer factors has emerged as an important tool for the development of regenerative therapies for the treatment of CVD. Pioneer factors bind closed chromatin and remodel it to drive lineage specification. Here, we review pioneer factors within the cardiovascular lineage, particularly during development and reprogramming and highlight the implications this field of research has for the future development of cardiac specific regenerative therapies.

Leafy and weedy seadragon genomes connect genic and repetitive DNA features to the extravagant biology of syngnathid fishes

Seadragons are widely recognized for their derived traits, which include leaf-like appendages and extreme spinal curvature. Efforts to understand the genetic basis of these unique traits and conserve these species and their relatives have been limited by genomic resource gaps. In this paper we present full, annotated genomes of leafy and weedy seadragons, which we use to uncover surprising features of gene family and genome architecture evolution that likely relate to the extravagant phenotypic traits of seadragons and their pipefish and seahorse relatives. These genomes and their analyses are important advances for the study of elaborate vertebrate traits, leveraging this diverse, morphologically exceptional group of fishes.

Seadragons are a remarkable lineage of teleost fishes in the family Syngnathidae, renowned for having evolved male pregnancy. Comprising three known species, seadragons are widely recognized and admired for their fantastical body forms and coloration, and their specific habitat requirements have made them flagship representatives for marine conservation and natural history interests. Until recently, a gap has been the lack of significant genomic resources for seadragons. We have produced gene-annotated, chromosome-scale genome models for the leafy and weedy seadragon to advance investigations of evolutionary innovation and elaboration of morphological traits in seadragons as well as their pipefish and seahorse relatives. We identified several interesting features specific to seadragon genomes, including divergent noncoding regions near a developmental gene important for integumentary outgrowth, a high genome-wide density of repetitive DNA, and recent expansions of transposable elements and a vesicular trafficking gene family. Surprisingly, comparative analyses leveraging the seadragon genomes and additional syngnathid and outgroup genomes revealed striking, syngnathid-specific losses in the family of fibroblast growth factors (FGFs), which likely involve reorganization of highly conserved gene regulatory networks in ways that have not previously been documented in natural populations. The resources presented here serve as important tools for future evolutionary studies of developmental processes in syngnathids and hold value for conservation of the extravagant seadragons and their relatives.

ETV2 functions as a pioneer factor to regulate and reprogram the endothelial lineage

The vasculature is an essential organ for the delivery of blood and oxygen to all tissues of the body and is thus relevant to the treatment of ischaemic diseases, injury-induced regeneration and solid tumour growth. Previously, we demonstrated that ETV2 is an essential transcription factor for the development of cardiac, endothelial and haematopoietic lineages. Here we report that ETV2 functions as a pioneer factor that relaxes closed chromatin and regulates endothelial development. By comparing engineered embryonic stem cell differentiation and reprogramming models with multi-omics techniques, we demonstrated that ETV2 was able to bind nucleosomal DNA and recruit BRG1. BRG1 recruitment remodelled chromatin around endothelial genes and helped to maintain an open configuration, resulting in increased H3K27ac deposition. Collectively, these results will serve as a platform for the development of therapeutic initiatives directed towards cardiovascular diseases and solid tumours.

Interspecies chimeras as a platform for exogenic organ production and transplantation

Chronic diseases are associated with considerable morbidity and mortality. Therefore, new therapeutic strategies are warranted. Here, we provide a brief review outlining the rationale and feasibility for the generation of intraspecies and interspecies chimeras, which one day may serve as a platform for organ transplantation. These strategies are further associated with consideration of scientific and ethical issues.

MiR-22 regulated T cell differentiation and hepatocellular carcinoma growth by directly targeting Jarid2

MiR-22 has been demonstrated to inhibits tumor growth in several cancers. However, its function in the tumor microenvironment is still unclear, especially for T cell differentiation. Here, miR-22 expression in the circulating T cells from hepatocellular carcinoma (HCC) patients and healthy controls was analyzed with quantitative polymerase chain reaction (qPCR). Diethylnitrosamine (DEN)/phenobarbital (PB)-mediated primary HCC and Hepa1-6 subcutaneous tumor mouse models were established and subjected to lenti-miR-22 injection. Mice immunoreconstituted with miR-22-overexpressing T cells were employed to investigate the antitumor effect of miR-22 in mice. Luciferase assay, immunofluorescent staining, in vitro Th17 cell differentiation assay, and rescue experiments were employed to investigate the mechanism underlying the miR-22-mediated regulation of Th17 cell differentiation and liver tumor growth. Results confirmed the dramatic downregulation of miR-22 expression in malignant tissues and circulating T cells from patients with HCC. MiR-22 expression correlated with good prognosis of patients. Overexpression of miR-22 impaired the DEN/PB-induced primary HCC formation and the growth of Hepa1-6 subcutaneous tumors by promoting Th17 differentiation. Injection of miR-22-overexpressing T cells in irradiated mice resulted in the inhibition of Hepa1-6 subcutaneous tumor growth via Th17 differentiation promotion. MiR-22 could directly bind to Jarid2, which played an important role during the miR-22-mediated regulation of Th17 differentiation. Taken together, our study expands the understanding of miR-22 function and provides a therapy target for HCC.

ETV2 (Ets Variant Transcription Factor 2)-Rhoj Cascade Regulates Endothelial Progenitor Cell Migration During Embryogenesis

OBJECTIVE

Endothelial progenitors migrate early during embryogenesis to form the primary vascular plexus. The regulatory mechanisms that govern their migration are not completely defined. Here, we describe a novel role for ETV2 (Ets variant transcription factor 2) in cell migration and provide evidence for an ETV2-Rhoj network as a mechanism responsible for this process. Approach and Results: Analysis of RNAseq datasets showed robust enrichment of migratory/motility pathways following overexpression of ETV2 during mesodermal differentiation. We then analyzed ETV2 chromatin immunoprecipitation-seq and assay for transposase accessible chromatin-seq datasets, which showed enrichment of chromatin immunoprecipitation-seq peaks with increased chromatin accessibility in migratory genes following overexpression of ETV2. Migratory assays showed that overexpression of ETV2 enhanced cell migration in mouse embryonic stem cells, embryoid bodies, and mouse embryonic fibroblasts. Knockout of Etv2 led to migratory defects of Etv2-EYFP⁺ angioblasts to their predefined regions of developing embryos relative to wild-type controls at embryonic day (E) 8.5, supporting its role during migration. Mechanistically, we showed that ETV2 binds the promoter region of Rhoj serving as an upstream regulator of cell migration. Single-cell RNAseq analysis of Etv2-EYFP⁺ sorted cells revealed coexpression of Etv2 and Rhoj in endothelial progenitors at E7.75 and E8.25. Overexpression of ETV2 led to a robust increase in Rhoj in both embryoid bodies and mouse embryonic fibroblasts, whereas, its expression was abolished in the Etv2 knockout embryoid bodies. Finally, shRNA-mediated knockdown of Rhoj resulted in migration defects, which were partially rescued by overexpression of ETV2.

CONCLUSIONS

These results define an ETV2-Rhoj cascade, which is important for the regulation of endothelial progenitor cell migration.

Convergences of Life Sciences and Engineering in Understanding and Treating Heart Failure

On March 1 and 2, 2018, the National Institutes of Health 2018 Progenitor Cell Translational Consortium, Cardiovascular Bioengineering Symposium, was held at the University of Alabama at Birmingham. Convergence of life sciences and engineering to advance the understanding and treatment of heart failure was the theme of the meeting. Over 150 attendees were present, and >40 scientists presented their latest work on engineering human functional myocardium for disease modeling, drug development, and heart failure research. The scientists, engineers, and physicians in the field of cardiovascular sciences met and discussed the most recent advances in their work and proposed future strategies for overcoming the major roadblocks of cardiovascular bioengineering and therapy. Particular emphasis was given for manipulation and using of stem/progenitor cells, biomaterials, and methods to provide molecular, chemical, and mechanical cues to cells to influence their identity and fate in vitro and in vivo. Collectively, these works are profoundly impacting and progressing toward deciphering the mechanisms and developing novel treatments for left ventricular dysfunction of failing hearts. Here, we present some important perspectives that emerged from this meeting.

Molecular regulation of arteriovenous endothelial cell specification

The systemic circulation depends upon a highly organized, hierarchal blood vascular network that requires the successful specification of arterial and venous endothelial cells during development. This process is driven by a cascade of signaling events (including Hedgehog, vascular endothelial growth factor (VEGF), Notch, connexin (Cx), transforming growth factor-beta (TGF- β), and COUP transcription factor 2 (COUP-TFII)) to influence endothelial cell cycle status and expression of arterial or venous genes and is further regulated by hemodynamic flow. Failure of endothelial cells to properly undergo arteriovenous specification may contribute to vascular malformation and dysfunction, such as in hereditary hemorrhagic telangiectasia (HHT) and capillary malformation-arteriovenous malformation (CM-AVM) where abnormal vessel structures, such as large shunts lacking clear arteriovenous identity and function, form and compromise peripheral blood flow. This review provides an overview of recent findings in the field of arteriovenous specification and highlights key regulators of this process.

The Role of Non-Coding RNA in Congenital Heart Diseases

Cardiovascular development is a complex developmental process starting with the formation of an early straight heart tube, followed by a rightward looping and the configuration of atrial and ventricular chambers. The subsequent step allows the separation of these cardiac chambers leading to the formation of a four-chambered organ. Impairment in any of these developmental processes invariably leads to cardiac defects. Importantly, our understanding of the developmental defects causing cardiac congenital heart diseases has largely increased over the last decades. The advent of the molecular era allowed to bridge morphogenetic with genetic defects and therefore our current understanding of the transcriptional regulation of cardiac morphogenesis has enormously increased. Moreover, the impact of environmental agents to genetic cascades has been demonstrated as well as of novel genomic mechanisms modulating gene regulation such as post-transcriptional regulatory mechanisms. Among post-transcriptional regulatory mechanisms, non-coding RNAs, including therein microRNAs and lncRNAs, are emerging to play pivotal roles. In this review, we summarize current knowledge on the functional role of non-coding RNAs in distinct congenital heart diseases, with particular emphasis on microRNAs and long non-coding RNAs.

A conserved HH-Gli1-Mycn network regulates heart regeneration from newt to human

The mammalian heart has a limited regenerative capacity and typically progresses to heart failure following injury. Here, we defined a hedgehog (HH)-Gli1-Mycn network for cardiomyocyte proliferation and heart regeneration from amphibians to mammals. Using a genome-wide screen, we verified that HH signaling was essential for heart regeneration in the injured newt. Next, pharmacological and genetic loss- and gain-of-function of HH signaling demonstrated the essential requirement for HH signaling in the neonatal, adolescent, and adult mouse heart regeneration, and in the proliferation of hiPSC-derived cardiomyocytes. Fate-mapping and molecular biological studies revealed that HH signaling, via a HH-Gli1-Mycn network, contributed to heart regeneration by inducing proliferation of pre-existing cardiomyocytes and not by de novo cardiomyogenesis. Further, Mycn mRNA transfection experiments recapitulated the effects of HH signaling and promoted adult cardiomyocyte proliferation. These studies defined an evolutionarily conserved function of HH signaling that may serve as a platform for human regenerative therapies.

Due to the limited proliferation capacity of adult mammalian cardiomyocytes, the human heart has negligible regenerative capacity after injury. Here the authors show that a Hedgehog-Gli1-Mycn signaling cascade regulates cardiomyocyte proliferation and cardiac regeneration from amphibians to mammals.

Hedgehog and Wnt Signaling Pathways Regulate Tail Regeneration

Urodele amphibians have a tremendous capacity for the regeneration of appendages, including limb and tail, following injury. While studies have focused on the cellular and morphological changes during appendicular regeneration, the signaling mechanisms that govern these cytoarchitectural changes during the regenerative response are unclear. In this study, we describe the essential role of hedgehog (Hh) and Wnt signaling pathways following tail amputation in the newt. Quantitative PCR studies revealed that members of both the Hh and Wnt signaling pathways, including the following: shh, ihh, ptc-1, wnt-3a, β-catenin, axin2, frizzled (frzd)-1, and frzd-2 transcripts, were induced following injury. Continuous pharmacological-mediated inhibition of Hh signaling resulted in spike-like regenerates with no evidence of tissue patterning, whereas activation of Hh signaling enhanced the regenerative process. Pharmacological-mediated temporal inhibition experiments demonstrated that the Hh-mediated patterning of the regenerating tail occurs early during regeneration and Hh signals are continuously required for proliferation of the blastemal progenitors. BrdU incorporation and PCNA immunohistochemical studies demonstrated that Hh signaling regulates the cellular proliferation of the blastemal cells following amputation. Similarly, Wnt inhibition resulted in perturbed regeneration, whereas its activation promoted tail regeneration. Using an inhibitor-activator strategy, we demonstrated that the Wnt pathway is likely to be upstream of the Hh pathway and together these signaling pathways function in a coordinated manner to facilitate tail regeneration. Mechanistically, the Wnt signaling pathway activated the Hh signaling pathway that included ihh and ptc-1 during the tail regenerative process. Collectively, our results demonstrate the absolute requirement of signaling pathways that are essential in the regulation of tail regeneration.