Gata4 regulates the formation of multiple organs

Pyraclostrobin induces developmental toxicity and cardiotoxicity through oxidative stress and inflammation in zebrafish embryos

Pyraclostrobin, a typical representative of strobilurin fungicides, is extensively used in agriculture to control fungi and is often detected in water bodies and food. However, the comprehensive toxicological molecular mechanism of pyraclostrobin requires further study. To assess the toxic effects and underlying mechanisms of pyraclostrobin on aquatic organisms, zebrafish embryos were exposed to pyraclostrobin (20, 40, and 60 μg/L) until 96 h post fertilization (hpf). These results indicated that exposure to pyraclostrobin induces morphological alterations, including spinal curvature, shortened body length, and smaller eyes. Furthermore, heart developmental malformations, such as pericardial edema and bradycardia, were observed. This indicated severe cardiotoxicity induced by pyraclostrobin in zebrafish embryos, which was confirmed by the dysregulation of genes related to heart development. Besides, our findings also demonstrated that pyraclostrobin enhanced the contents of reactive oxygen species (ROS) and malondialdehyde (MDA), up-regulated catalase (CAT) activity, but inhibited superoxide dismutase (SOD) activity. Subsequently, the NF-κb signaling pathway was further studied, and the results indicated that the up-regulation of tnf-α, tlr-4, and myd88 activated the NF-κb signaling pathway and up-regulated the relative expression level of pro-inflammatory cytokines, such as cc-chemokine, ifn-γ, and cxcl-clc. Collectively, this study revealed that pyraclostrobin exposure induces developmental toxicity and cardiotoxicity, which may result from a combination of oxidative stress and inflammatory responses. These findings provide a basis for continued evaluation of the effects and ecological risks of pyraclostrobin on the early development of aquatic organisms.

Hexafluoropropylene oxide trimer acid, a perfluorooctanoic acid alternative, induces cardiovascular toxicity in zebrafish embryos

As an increasingly used alternative to perfluorooctanoic acid (PFOA), hexafluoropropylene oxide trimer acid (HFPO-TA) has been widely detected in global water environments. However, little is known regarding its toxic effects on cardiovascular development. Here, zebrafish embryos were treated with egg water containing 0, 60, 120, or 240 mg/L HFPO-TA. Results showed that HFPO-TA treatment led to a significant reduction in both larval survival percentage and heart rate. Furthermore, HFPO-TA exposure caused severe pericardial edema and elongation of the sinus venous to bulbus arteriosus distance (SV-BA) in Tg (myl7: GFP) transgenic larvae, disrupting the expression of genes involved in heart development and thus causing abnormal heart looping. Obvious sprouting angiogenesis was observed in the 120 and 240 mg/L exposed Tg (fli: GFP) transgenic larvae. HFPO-TA treatment also impacted the mRNA levels of genes involved in the vascular endothelial growth factor (VEGF) pathway and embryonic vascular development. HFPO-TA exposure significantly decreased erythrocyte number in Tg (gata1: DsRed) transgenic embryos and influenced gene expression associated with the heme metabolism pathway. HFPO-TA also induced oxidative stress and altered the transcriptional levels of genes related to cell cycle and apoptosis, inhibiting cell proliferation while promoting apoptosis. Therefore, HFPO-TA exposure may induce abnormal development of the cardiovascular and hematopoietic systems in zebrafish embryos, suggesting it may not be a suitable or safe alternative for PFOA.

Hhex and Prox1a synergistically dictate the hepatoblast to hepatocyte differentiation in zebrafish

The specification of endoderm cells to prospective hepatoblasts is the starting point for hepatogenesis. However, how a prospective hepatoblast gains the hepatic fate remains elusive. Previous studies have shown that loss-of-function of either hhex or prox1a alone causes a small liver phenotype but without abolishing the hepatocyte differentiation, suggesting that absence of either Hhex or Prox1a alone is not sufficient to block the hepatoblast differentiation. Here, via genetic studies of the zebrafish two single (hhex-/- and prox1a-/-) and one double (hhex-/-prox1a-/-) mutants, we show that simultaneous loss-of-function of the hhex and prox1a two genes does not block the endoderm cells to gain the hepatoblast potency but abolishes the hepatic differentiation from the prospective hepatoblast. Consequently, the hhex-/-prox1a-/- double mutant displays a liverless phenotype that cannot be rescued by the injection of bmp2a mRNA. Taken together, we provide strong evidences showing that Hhex teams with Prox1a to act as a master control of the differentiation of the prospective hepatoblasts towards hepatocytes.

Waterborne Tebuconazole Exposure Induces Male-Biased Sex Differentiation in Zebrafish (Danio rerio) Larvae via Aromatase Inhibition

Tebuconazole is a widely used fungicide for various crops that targets sterol 14-α-demethylase (CYP51) in fungi. However, attention has shifted to aromatase (CYP19) due to limited research indicating its reproductive impact on aquatic organisms. Herein, zebrafish were exposed to 0.5 mg/L tebuconazole at different developmental stages. The proportion of males increased significantly after long-term exposure during the sex differentiation phase (0-60, 5-60, and 19-60 days postfertilization (dpf)). Testosterone levels increased and 17β-estradiol and cyp19a1a expression levels decreased during the 5-60 dpf exposure, while the sex ratio was equally distributed on coexposure with 50 ng/L 17β-estradiol. Chemically activated luciferase gene expression bioassays determined that the male-biased sex differentiation was not caused by tebuconazole directly binding to sex hormone receptors. Protein expression and phosphorylation levels were specifically altered in the vascular endothelial growth factor signaling pathway despite excluding the possibility of tebuconazole directly interacting with kinases. Aromatase was selected for potential target analysis. Molecular docking and aromatase activity assays demonstrated the interactions between tebuconazole and aromatase, highlighting that tebuconazole poses a threat to fish populations by inducing a gender imbalance.

Key transcriptional effectors of the pancreatic acinar phenotype and oncogenic transformation

Proper maintenance of mature cellular phenotypes is essential for stable physiology, suppression of disease states, and resistance to oncogenic transformation. We describe the transcriptional regulatory roles of four key DNA-binding transcription factors (Ptf1a, Nr5a2, Foxa2 and Gata4) that sit at the top of a regulatory hierarchy controlling all aspects of a highly differentiated cell-type-the mature pancreatic acinar cell (PAC). Selective inactivation of Ptf1a, Nr5a2, Foxa2 and Gata4 individually in mouse adult PACs rapidly altered the transcriptome and differentiation status of PACs. The changes most emphatically included transcription of the genes for the secretory digestive enzymes (which conscript more than 90% of acinar cell protein synthesis), a potent anabolic metabolism that provides the energy and materials for protein synthesis, suppressed and properly balanced cellular replication, and susceptibility to transformation by oncogenic KrasG12D. The simultaneous inactivation of Foxa2 and Gata4 caused a greater-than-additive disruption of gene expression and uncovered their collaboration to maintain Ptf1a expression and control PAC replication. A measure of PAC dedifferentiation ranked the effects of the conditional knockouts as Foxa2+Gata4 > Ptf1a > Nr5a2 > Foxa2 > Gata4. Whereas the loss of Ptf1a or Nr5a2 greatly accelerated Kras-mediated transformation of mature acinar cells in vivo, the absence of Foxa2, Gata4, or Foxa2+Gata4 together blocked transformation completely, despite extensive dedifferentiation. A lack of correlation between PAC dedifferentiation and sensitivity to oncogenic KrasG12D negates the simple proposition that the level of differentiation determines acinar cell resistance to transformation.

GATA4 inhibits odontoblastic differentiation of dental pulp stem cells through targeting IGFBP3

OBJECTIVE

The odontogenic differentiation of human dental pulp stem cells (HDPSCs) is associated with reparative dentinogenesis. Transcription factor GATA binding protein 4 (GATA4) is proved to be essential for osteoblast differentiation and bone remodeling. This study clarified the function of GATA4 in HDPSCs odontoblast differentiation.

METHODS

The change in GATA4 expression during reparative dentin formation was detected by immunohistochemistry staining. The expression of GATA4 during HDPSCs odontoblastic differentiation was detected by western blot and quantitative polymerase chain reaction. The effect of GATA4 on odontoblast differentiation was investigated following overexpression lentivirus transfection. RNA sequencing, dual luciferase assay and chromatin immunoprecipitation (CHIP) were conducted to verify downstream targets of GATA4. GATA4 overexpression lentivirus and small interference RNA targeting IGFBP3 were co-transfected to investigate the regulatory mechanism of GATA4.

RESULTS

Upregulated GATA4 was observed during reparative dentin formation in vivo and the odontoblastic differentiation of HDPSCs in vitro. GATA4 overexpression suppressed the odontoblastic potential of HDPSCs, demonstrated by decreased alkaline phosphatase activity (p < 0.0001), mineralized nodules formation (p < 0.01), and odonto/osteogenic differentiation markers levels (p < 0.05). RNA sequencing revealed IGFBP3 was a potential target of GATA4. CHIP and dual luciferase assays identified GATA4 could activate IGFBP3 transcription. Additionally, IGFBP3 knockdown recovered the odontoblastic differentiation defect caused by GATA4 overexpression (p < 0.05).

CONCLUSIONS

GATA4 inhibited odontoblastic differentiation of HDPSCs via activating the transcriptional activity of IGFBP3, identifying its promising role in regulating HDPSCs odontoblast differentiation and reparative dentinogenesis.

Identification of Potential Abnormal Methylation-Modified Genes in Coronary Artery Ectasia

Background

Coronary artery ectasia (CAE) is an easily recognized abnormality of coronary artery anatomy and morphology. However, its pathogenesis remains unclear.

Objectives

This study aimed to identify abnormal methylation-modified genes in patients with CAE, which could provide a research basis for CAE.

Methods

Peripheral venous blood samples from patients with CAE were collected for RNA sequencing to identify differentially expressed genes (DEGs), followed by functional enrichment. Then, the DNA methylation profile of CAE was downloaded from GSE87016 (HumanMethylation450 BeadChip data, involving 11 cases and 12 normal controls) to identify differentially methylated genes (DMGs). Finally, after taking interaction genes between DEGs and DMGs, abnormal methylation-modified genes were identified, followed by protein-protein interaction analysis and expression validation using reverse transcriptase polymerase chain reaction.

Results

A total of 152 DEGs and 4318 DMGs were obtained from RNA sequencing and the GSE87016 dataset, respectively. After taking interaction genes, 9 down-regulated DEGs due to hypermethylation and 11 up-regulated DEGs due to hypomethylation were identified in CAE. A total of 10 core abnormal methylation-modified genes were identified, including six down-regulated DEGs due to hypermethylation (netrin G1, ADAM metallopeptidase domain 12, immunoglobulin superfamily member 10, sarcoglycan dela, Dickkopf WNT signaling pathway inhibitor 3, and GATA binding protein 6), and four up-regulated DEGs due to hypomethylation (adrenomedullin, ubiquitin specific peptidase 18, lymphocyte antigen 6 family member E, and MX dynamin-like GTPase 1). Some signaling pathways were identified in patients with CAE, including cell adhesion molecule, O-glycan biosynthesis, and the renin-angiotensin system.

Conclusions

Abnormal methylation-modified DEGs involved in signaling pathways may be involved in CAE development.

CRISPR-based knockout and base editing confirm the role of MYRF in heart development and congenital heart disease

High-throughput DNA sequencing studies increasingly associate DNA variants with congenital heart disease (CHD). However, functional modeling is a crucial prerequisite for translating genomic data into clinical care. We used CRISPR-Cas9-mediated targeting of 12 candidate genes in the vertebrate model medaka (Oryzias latipes), five of which displayed a novel cardiovascular phenotype spectrum in F0 (crispants): mapre2, smg7, cdc42bpab, ankrd11 and myrf, encoding a transcription factor recently linked to cardiac-urogenital syndrome. Our myrf mutant line showed particularly prominent embryonic cardiac defects recapitulating phenotypes of pediatric patients, including hypoplastic ventricle. Mimicking human mutations, we edited three sites to generate specific myrf single-nucleotide variants via cytosine and adenine base editors. The Glu749Lys missense mutation in the conserved intramolecular chaperon autocleavage domain fully recapitulated the characteristic myrf mutant phenotype with high penetrance, underlining the crucial function of this protein domain. The efficiency and scalability of base editing to model specific point mutations accelerate gene validation studies and the generation of human-relevant disease models.

FXR and NASH: an avenue for tissue-specific regulation

NASH is within the spectrum of NAFLD, a liver condition encompassing liver steatosis, inflammation, hepatocyte injury, and fibrosis. The prevalence of NASH-induced cirrhosis is rapidly rising and has become the leading indicator for liver transplantation in the US. There is no Food and Drug Administration (FDA)-approved pharmacological intervention for NASH. The farnesoid X receptor (FXR) is essential in regulating bile acid homeostasis, and dysregulation of bile acids has been implicated in the pathogenesis of NASH. As a result, modulators of FXR that show desirable effects in mitigating key characteristics of NASH have been developed as promising therapeutic approaches. However, global FXR activation causes adverse effects such as cholesterol homeostasis imbalance and pruritus. The development of targeted FXR modulation is necessary for ideal NASH therapeutics, but information regarding tissue-specific and cell-specific FXR functionality is limited. In this review, we highlight FXR activation in the regulation of bile acid homeostasis and NASH development, examine the current literature on tissue-specific regulation of nuclear receptors, and speculate on how FXR regulation will be beneficial in the treatment of NASH.

Benomyl-induced development and cardiac toxicity in zebrafish embryos

Benomyl is a highly effective broad-spectrum fungicide widely used worldwide to control vegetable, fruit, and oil crop diseases. However, the mechanism of its toxicity to aquatic organisms and humans remains unknown. In this study, zebrafish were used to determine the toxicity of benomyl. It was found to be highly toxic, with a 72-h post-fertilization (hpf) lethal concentration 50 (LC₅₀) of 1.454 mg/L. Benomyl induced severe developmental toxicity, including shorter body length, slower heart rate, and a reduced yolk absorption rate. Benomyl also increased oxidative stress in zebrafish, especially in the heart and head, as well as increasing malondialdehyde (MDA) content and decreasing catalase (CAT) and superoxide dismutase (SOD) activities. This indicates that benomyl induced reactive oxygen species (ROS) production and cell membrane peroxidation in vivo. Acridine orange (AO) staining and apoptosis factor detection further indicated that benomyl induced apoptosis in zebrafish. Overall, these findings demonstrate that benomyl disrupts cellular homeostasis by activating oxidative stress in zebrafish, resulting in an imbalance of cardiac development-related gene expression and apoptosis, which causes severe developmental toxicity and cardiac dysfunction. This study evaluated the in vivo toxicity of benomyl, which is a potential threat to aquatic organisms and humans. Possible toxicity mechanisms are explored, providing a valuable reference for the safe use of benomyl.

Cdx1b protects intestinal cell fate by repressing signaling networks for liver specification

In mammals, the expression of the homeobox family member Cdx2/CDX2 is restricted within the intestine. Conditional ablation of the mouse Cdx2 in the endodermal cells causes a homeotic transformation of the intestine towards the esophagus or gastric fate. In this report, we show that null mutants of zebrafish cdx1b, encoding the counterpart of mammalian CDX2, could survive more than 10 days post fertilization, a stage when the zebrafish digestive system has been well developed. Through RNA sequencing (RNA-seq) and single-cell sequencing (scRNA-seq) of the dissected intestine from the mutant embryos, we demonstrate that the loss-of-function of the zebrafish cdx1b yields hepatocyte-like intestinal cells, a phenotype never observed in the mouse model. Further RNA-seq data analysis, and genetic double mutants and signaling inhibitor studies reveal that Cdx1b functions to guard the intestinal fate by repressing, directly or indirectly, a range of transcriptional factors and signaling pathways for liver specification. Finally, we demonstrate that heat shock-induced overexpression of cdx1b in a transgenic fish abolishes the liver formation. Therefore, we demonstrate that Cdx1b is a key repressor of hepatic fate during the intestine specification in zebrafish.

Unraveling Differential Transcriptomes and Cell Types in Zebrafish Larvae Intestine and Liver

The zebrafish intestine and liver, as in other vertebrates, are derived from the endoderm. Great effort has been devoted to deciphering the molecular mechanisms controlling the specification and development of the zebrafish intestine and liver; however, genome-wide comparison of the transcriptomes between these two organs at the larval stage remains unexplored. There is a lack of extensive identification of feature genes marking specific cell types in the zebrafish intestine and liver at 5 days post-fertilization, when the larval fish starts food intake. In this report, through RNA sequencing and single-cell RNA sequencing of intestines and livers separately dissected from wild-type zebrafish larvae at 5 days post-fertilization, together with the experimental validation of 47 genes through RNA whole-mount in situ hybridization, we identified not only distinctive transcriptomes for the larval intestine and liver, but also a considerable number of feature genes for marking the intestinal bulb, mid-intestine and hindgut, and for marking hepatocytes and cholangiocytes. Meanwhile, we identified 135 intestine- and 97 liver-enriched transcription factor genes in zebrafish larvae at 5 days post-fertilization. Our findings provide rich molecular and cellular resources for studying cell patterning and specification during the early development of the zebrafish intestine and liver.

Towards Understanding the Gene-Specific Roles of GATA Factors in Heart Development: Does GATA4 Lead the Way?

Transcription factors play crucial roles in the regulation of heart induction, formation, growth and morphogenesis. Zinc finger GATA transcription factors are among the critical regulators of these processes. GATA4, 5 and 6 genes are expressed in a partially overlapping manner in developing hearts, and GATA4 and 6 continue their expression in adult cardiac myocytes. Using different experimental models, GATA4, 5 and 6 were shown to work together not only to ensure specification of cardiac cells but also during subsequent heart development. The complex involvement of these related gene family members in those processes is demonstrated through the redundancy among them and crossregulation of each other. Our recent identification at the genome-wide level of genes specifically regulated by each of the three family members and our earlier discovery that gata4 and gata6 function upstream, while gata5 functions downstream of noncanonical Wnt signalling during cardiac differentiation, clearly demonstrate the functional differences among the cardiogenic GATA factors. Such suspected functional differences are worth exploring more widely. It appears that in the past few years, significant advances have indeed been made in providing a deeper understanding of the mechanisms by which each of these molecules function during heart development. In this review, I will therefore discuss current evidence of the role of individual cardiogenic GATA factors in the process of heart development and emphasize the emerging central role of GATA4.

An EGFP Knock-in Zebrafish Experimental Model Used in Evaluation of the Amantadine Drug Safety During Early Cardiogenesis

Background

Drug exposure during gestation or in prematurely born children represents a significant risk to congenital heart disease (CHD). Amantadine is an antiviral agent also effective in the treatment of Parkinson’s disease. However, while its potential side effects associated with tetralogy of fallot (ToF) and birth defects were implicated, its underlying etiologic mechanisms of action remain unknown. Here, we report teratogenic effects of amantadine drug during early cardiogenesis through developing a novel zebrafish (Danio rerio) knock-in (KI) animal model and explore the underlying mechanisms.

Methods

Homologous recombination (HR) pathway triggered by CRISPR/Cas9 system was utilized to generate an enhanced green fluorescent protein (EGFP) KI zebrafish animal model. Dynamic fluorescence imaging coupled with a whole-mount in-situ hybridization (WISH) assay was employed to compare the spatial and temporal expression patterns of the EGFP reporter in the KI animal model with the KI-targeted endogenous gene. Heart morphology and EGFP expression dynamics in the KI animal models were monitored to assess cardiac side effects of different doses of amantadine hydrochloride. Expression of key genes required for myocardium differentiation and left–right (LR) asymmetry was analyzed using WISH and quantitative reverse transcription-PCR (RT-PCR).

Results

A novel EGFP KI line targeted at the ventricular myosin heavy chain (vmhc) gene locus was successfully generated, in which EGFP reporter could faithfully recapitulate the endogenous expression dynamics of the ventricle chamber-specific expression of the vmhc gene. Amantadine drug treatment-induced ectopic expression of vmhc gene in the atrium and caused cardiac-looping or LR asymmetry defects to dose-dependently during early cardiogenesis, concomitant with dramatically reduced expression levels of key genes required for myocardium differentiation and LR asymmetry.

Conclusion

We generated a novel zebrafish KI animal model in which EGFP reports the ventricle chamber-specific expression of vmhc gene dynamics that is useful to effectively assess drug safety on the cardiac morphology in vivo. Specifically, this study identified teratogenic effects of amantadine drug during early cardiogenesis dose dependent, which could be likely conveyed by inhibiting expression of key genes required for cardiac myocardium differentiation and LR asymmetry.

Pioneer factors as master regulators of the epigenome and cell fate

Pioneer factors are transcription factors with the unique ability to initiate opening of closed chromatin. The stability of cell identity relies on robust mechanisms that maintain the epigenome and chromatin accessibility to transcription factors. Pioneer factors counter these mechanisms to implement new cell fates through binding of DNA target sites in closed chromatin and introduction of active-chromatin histone modifications, primarily at enhancers. As master regulators of enhancer activation, pioneers are thus crucial for the implementation of correct cell fate decisions in development, and as such, they hold tremendous potential for therapy through cellular reprogramming. The power of pioneer factors to reshape the epigenome also presents an Achilles heel, as their misexpression has major pathological consequences, such as in cancer. In this Review, we discuss the emerging mechanisms of pioneer factor functions and their roles in cell fate specification, cellular reprogramming and cancer.

Hallmarks of exercised heart

The benefits of exercise in humans on the heart have been well recognized for many years. Long-term endurance exercise training can induce physiologic cardiac hypertrophy with normal or enhanced heart function, and provide protective benefits in preventing heart failure. The heart-specific responses that occur during exercise are complex and highly variable. This review mainly focuses on the current understanding of the structural and functional cardiac adaptations to exercise as well as molecular pathways and signaling proteins responsible for these changes. Here, we summarize eight tentative hallmarks that represent common denominators of the exercised heart. These hallmarks are: cardiomyocyte growth, cardiomyocyte fate reprogramming, angiogenesis and lymphangiogenesis, mitochondrial remodeling, epigenetic alteration, enhanced endothelial function, quiescent cardiac fibroblast, and improved cardiac metabolism. A major challenge is to explore the underlying molecular mechanisms for cardio-protective effects of exercise, and to identify therapeutic targets for heart diseases.

Melatonin mitigated circadian disruption and cardiovascular toxicity caused by 6-benzylaminopurine exposure in zebrafish

As a highly effective plant hormone, the overuse of 6-benzylaminopurine (6-BA) may pose potential threats to organisms and the environment. Melatonin is widely known for its regulation of sleep rhythm, and it also shows a beneficial effect in a variety of adverse situations. In order to investigate the harm of 6-BA to vertebrates and whether melatonin can reverse the toxicity induced by 6-BA, we analyzed the circadian rhythm and cardiovascular system of zebrafish, and further clarified the role of the thyroid endocrine system. The exposure of well-developed embryos started at 2 hpf, then 6-BA and/or melatonin were carried out. The results indicated that 6-BA disturbed the rhythmic activities of the larvae, increased wakefulness, correspondingly reduced their rest, and induced disrupted clock gene expression. Video analysis and qRT-PCR data found that zebrafish under 6-BA exposure showed obvious cardiovascular morphological abnormalities and dysfunction, and the mRNA levels of cardiovascular-related genes (nkx2.5, gata4, myl7, vegfaa and vegfab) were significantly down-regulated. In addition, altered thyroid hormone content and hypothalamus-pituitary-thyroid (HPT) axis-related gene expression were also clearly observed. 1umol/L of melatonin had little effect on zebrafish, but its addition could significantly alleviate the circadian disturbance and cardiovascular toxicity caused by 6-BA, and simultaneously played a regulatory role in thyroid system. Our research revealed the adverse effects of 6-BA on zebrafish larvae and the protective role of melatonin in circadian rhythm, cardiovascular and thyroid systems.

GATA binding protein 4 promotes the expression and transcription of hepatitis B virus by facilitating hepatocyte nuclear factor 4 alpha in vitro

Background

GATA binding protein 4 (GATA4) has been reported as a potential target of gene therapy for hepatocellular carcinoma (HCC). It is well known that the main cause of HCC is the chronic infection of hepatitis B virus (HBV). However, whether the effect of GATA4 on HBV has not yet been reported.

Methods

In this study, the regulation of GATA4 on HBV was analyzed in vitro. In turn, the effect of HBV on GATA4 was also observed in vitro, in vivo, and clinical HCC patients. Subsequently, we analyzed whether the effect of GATA4 on HBV was related to hepatocyte nuclear factor 4 alpha (HNF4α) in vitro.

Results

The results showed that GATA4 significantly promoted the secretion of HBV surface antigen (HBsAg) and HBV e antigen in the cell culture medium, improved the replication of HBV genomic DNA, and increased the level of HBV 3.5 kb pre-genomic RNA and HBV total RNA (P < 0.05). Moreover, it was showed that HBV had no significant effect on GATA4 in vitro and in vivo (P > 0.05). At the same time, GATA4 expression was decreased in 78.9% (15/19) of HCC patients regardless of the HBV and HBsAg status. Among them, there were 76.9% (10/13) in HBV-associated patients with HCC (HBV-HCC), and 83.3% (5/6) in non-HBV-HCC patients. In addition, the expression of HNF4α was also up-regulated or down-regulated accordingly when stimulating or interfering with the expression of GATA4. Furthermore, stimulating the expression of HNF4α could only alleviate the HBsAg level and HBV transcription levels, but had no significant effect on GATA4.

Conclusions

In summary, this study found that GATA4 has a positive effect on HBV, and the potential pathway may be related to another transcription factor HNF4α that regulates HBV.

Effect of flupyradifurone on zebrafish embryonic development

Evaluation of the toxicity of pesticide residues on non-target organisms in the ecosystem is an important part of pesticide environmental risk assessment. Flupyradifurone is a new type of butenolide insecticide produced by Bayer, who claims it to be "low toxic" to non-target organisms in the environment. However, there is little evidence in the literature to show how flupyradifurone affects aquatic organism development. In the current study, zebrafish embryos were treated with 0.1, 0.15, and 0.2 mg/mL of flupyradifurone within 6.0-72 h past fertilization (hpf). We found that the half-lethal concentration (LC₅₀) of flupyradifurone for zebrafish embryos at 96 hpf was 0.21 mg/mL. Flupyradifurone decreases the heart rate, survival rate, and body length of zebrafish embryos. The flupyradifurone treatment also led to the failure of heart looping, and pericardial edema. Moreover, flupyradifurone increased the level of reactive oxygen species (ROS) and decreased the enzymatic catalysis of catalase (CAT) and superoxide dismutase (SOD). Alterations were induced in the transcription of apoptosis-related genes (bcl-2, bax, bax/bcl-2, p53 and caspase-9) and the heart development-related genes (gata4, myh6, nkx2.5, nppa, tbx2b, tbx5 and vmhc). In the current study, new evidences have been provided regarding the toxic effects of flupyradifurone and the risk of its residues in agricultural products and the environment.

Pyridaben induced cardiotoxicity during the looping stages of zebrafish (Danio rerio) embryos

Pyridaben is a widely used acaricide in agriculture and reaches a high concentration (97 μg/L) in paddy water for a short time when pyridaben was applied to rice. However, its toxicity to aquatic organisms is still poorly understood. Therefore, we assessed the pyridaben cardiotoxicity to aquatic organisms using the zebrafish (Danio rerio) model. We found that pyridaben is highly toxic to aquatic organisms, and LC₅₀ of pyridaben for zebrafish at 72 hpf was 100.6 μg/L. Pyridaben caused severe cardiac malformations and functional abnormalities. Morphologic abnormity included severe pericardial edema, cardiomegaly, decreased cardiomyocytes, thinning of the myocardial layer, linear heart, and increased the distance between sinus venous and bulbus arteriosus (SV-BA). Functional failure included arrhythmia, heart failure, and reduced pumping efficiency. The genes involved in heart development, WNT signaling, BMP signaling, ATPase, and cardiac troponin C were abnormally expressed in the pyridaben treatment group. Exposure to pyridaben increased oxidative stress and induced cell apoptosis. The above causes may lead to cardiac toxicity. The results suggest that pyridaben exposure induced elevated oxidative stress through the WNT signaling pathway, which in turn led to apoptosis in the heart and cardiotoxicity. Besides, pyridaben exposure at the critical stage of cardiac looping (24-36 hpf) resulted in the greatest cardiotoxicity. The chorion reduced the entry of pyridaben and protected zebrafish embryos, resulting in cardiotoxicity second only to the stage of cardiac looping. The study should provide valuable information that pyridaben exposure causes cardiotoxicity in zebrafish embryos and have potential health risks for other aquatic organisms and humans.

In Silico Prediction of Transcription Factor Collaborations Underlying Phenotypic Sexual Dimorphism in Zebrafish (Danio rerio)

The transcriptional regulation of gene expression in higher organisms is essential for different cellular and biological processes. These processes are controlled by transcription factors and their combinatorial interplay, which are crucial for complex genetic programs and transcriptional machinery. The regulation of sex-biased gene expression plays a major role in phenotypic sexual dimorphism in many species, causing dimorphic gene expression patterns between two different sexes. The role of transcription factor (TF) in gene regulatory mechanisms so far has not been studied for sex determination and sex-associated colour patterning in zebrafish with respect to phenotypic sexual dimorphism. To address this open biological issue, we applied bioinformatics approaches for identifying the predicted TF pairs based on their binding sites for sex and colour genes in zebrafish. In this study, we identified 25 (e.g., STAT6-GATA4; JUN-GATA4; SOX9-JUN) and 14 (e.g., IRF-STAT6; SOX9-JUN; STAT6-GATA4) potentially cooperating TFs based on their binding patterns in promoter regions for sex determination and colour pattern genes in zebrafish, respectively. The comparison between identified TFs for sex and colour genes revealed several predicted TF pairs (e.g., STAT6-GATA4; JUN-SOX9) are common for both phenotypes, which may play a pivotal role in phenotypic sexual dimorphism in zebrafish.

Mitigation of arsenic induced developmental cardiotoxicity by ferulic acid in zebrafish

We investigated whether ferulic acid (FA), a nutraceutical could mitigate the arsenic (As) induced cardiotoxicity. Zebrafish larvae (60 and 72 h post-fertilization [hpf]) were used to study the effect of FA on As at different time points (24 and 48 h after exposure). The FA exposure was given as pre-treatment (60 hpf) and simultaneous treatment (72 hpf) to translate the results for As contaminated areas. To accomplish this, the lethality assay was done, and based on the results, the dosage for As (1 mM) and FA (30 μM) was fixed. The FA intervention (30 μM) as 12 h pre-treatment (60 hpf) and simultaneous treatment along with As (72 hpf) decreased the As content in zebrafish larvae as evidenced by inductively coupled plasma-mass spectrometry. As exposure showed congenital deformities especially cardiac malformations in zebrafish larvae after 24 and 48 h. These teratogenic effects induced by As were reduced by FA supplementation in both groups. Also, o-dianisidine staining demonstrated that As treated larvae encountered abnormal cardiac function with reduced blood circulation, while FA supplementation reversed these effects. The acetylcholinesterase activity, a biomarker of As-induced cardiotoxicity was also found to be decreased in As group, which was rescued by FA. The modulation in the expression of the genes involved in cardiogenesis (nkx2.5, bmp2b, gata4, gata5, myh6, myl7, and tnnt2) further confirmed the ameliorative effect of FA on As induced malformations.

Early embryonic exposure to chlorpyrifos-cypermethrin combination induces pattern deficits in the heart of domestic hen

Exposure to chlorpyrifos-cypermethrin combination during early development resulted in defective looping and ventricular noncompaction of heart in domestic chicken. The study was extended to elucidate the molecular basis of this novel observation. The primary culture of chicken embryonic heart cells showed a concentration-dependent loss of viability when challenged with this combination of technical-grade insecticides. Comet assay, DNA ladder assay, and analyses of appropriate markers at transcript and protein levels, revealed that chlorpyrifos-cypermethrin combination induced cell death by activating apoptosis. Parallelly, the tissues derived from control and experimental group hearts were checked for apoptotic markers, and the result was much similar to that of the in-vitro study. Further analysis showed that chlorpyrifos-cypermethrin combination deranged the expression pattern of the transcriptional regulators of cardiogenesis, namely TBX20, GATA5, HAND2, and MYOCD. This, together with heightened apoptosis, could well be the reason behind the observed structural anomalies in the heart of chlorpyrifos-cypermethrin poisoned embryos.

Cartilage Endplate Stem Cells Transdifferentiate Into Nucleus Pulposus Cells via Autocrine Exosomes

Stem cells derived from cartilage endplate (CEP) cells (CESCs) repair intervertebral disc (IVD) injury; however, the mechanism remains unclear. Here, we evaluated whether CESCs could transdifferentiate into nucleus pulposus cells (NPCs) via autocrine exosomes and subsequently inhibit IVD degeneration. Exosomes derived from CESCs (CESC-Exos) were extracted and identified by ultra-high-speed centrifugation and transmission electron microscopy. The effects of exosomes on the invasion, migration, and differentiation of CESCs were assessed. The exosome-activating hypoxia-inducible factor (HIF)-1α/Wnt pathway was investigated using lenti-HIF-1α and Wnt agonists/inhibitors in cells and gene ontology and Kyoto Encyclopedia of Genes and Genomes enrichment analysis in normal and degenerated human CEP tissue. The effects of GATA binding protein 4 (GATA4) on transforming growth factor (TGF)-β expression and on the invasion, migration, and transdifferentiation of CESCs were investigated using lenti-GATA4, TGF-β agonists, and inhibitors. Additionally, IVD repair was investigated by injecting CESCs overexpressing GATA4 into rats. The results indicated that CESC-Exos promoted the invasion, migration, and differentiation of CESCs by autocrine exosomes via the HIF-1α/Wnt pathway. Additionally, increased HIF-1α enhanced the activation of Wnt signaling and activated GATA4 expression. GATA4 effectively promoted TGF-β secretion and enhanced the invasion, migration, and transdifferentiation of CESCs into NPCs, resulting in promotion of rat IVD repair. CESCs were also converted into NPCs as endplate degeneration progressed in human samples. Overall, we found that CESC-Exos activated HIF-1α/Wnt signaling via autocrine mechanisms to increase the expression of GATA4 and TGF-β1, thereby promoting the migration of CESCs into the IVD and the transformation of CESCs into NPCs and inhibiting IVDD.

Comprehensive multi-omics analysis of G6PC3 deficiency-related congenital neutropenia with inflammatory bowel disease

Autosomal recessive mutations in G6PC3 cause isolated and syndromic congenital neutropenia which includes congenital heart disease and atypical inflammatory bowel disease (IBD). In a highly consanguineous pedigree with novel mutations in G6PC3 and MPL, we performed comprehensive multi-omics analyses. Structural analysis of variant G6PC3 and MPL proteins suggests a damaging effect. A distinct molecular cytokine profile (cytokinome) in the affected proband with IBD was detected. Liquid chromatography-mass spectrometry-based proteomics analysis of the G6PC3-deficient plasma samples identified 460 distinct proteins including 75 upregulated and 73 downregulated proteins. Specifically, the transcription factor GATA4 and LST1 were downregulated while platelet factor 4 (PF4) was upregulated. GATA4 and PF4 have been linked to congenital heart disease and IBD respectively, while LST1 may have perturbed a variety of essential cell functions as it is required for normal cell-cell communication. Together, these studies provide potentially novel insights into the pathogenesis of syndromic congenital G6PC3 deficiency.

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Multi-omics approaches identify unique signatures

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Whole-exome sequencing reveals distinct cytokine profiles

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Expression of GATA4, PF4, and LST1 is dysregulated

Comparison of developmental toxicity of different surface modified CdSe/ZnS QDs in zebrafish embryos

Quantum dots (QDs) are new types of nanomaterials. Few studies have focused on the effect of different surface modified QDs on embryonic development. Herein, we compared the in vivo toxicity of CdSe/ZnS QDs with carboxyl (-COOH) and amino (-NH₂) modification using zebrafish embryos. After exposure, the two CdSe/ZnS QDs decreased the survival rate, hatching rate, and embryo movement of zebrafish. Moreover, we found QDs attached to the embryo membrane before hatching and the eyes, yolk and heart after hatching. The attached amount of carboxyl QDs was more. Consistently, the Cd content in embryos and larvae was higher in carboxyl QD-treatment. We further observed that the two QDs caused zebrafish pericardial edema and cardiac dysfunction. In line with it, both carboxyl and amino QDs up-regulated the transcription levels of cardiac development-related genes, and the levels were higher in carboxyl QD-treated groups. Furthermore, the chelator of Cd²⁺ diethylene triamine pentacetate acid could partially rescued the developmental toxicity caused by the two types of QDs suggesting that both the nature of QDs and the release of Cd²⁺ contribute to the developmental toxicity. In conclusion, the two CdSe/ZnS QDs have developmental toxicity and affect the cardiac development, and the carboxyl QDs is more toxic possibly due to the higher affinity and more release to embryos and larvae. Our study provides new knowledge that the surface functional modification of QDs is critical on the development on aquatic species, which is beneficial to develop and applicate QDs more safely and environment-friendly.

Exploring the Expression of Cardiac Regulators in a Vertebrate Extremophile: The Cichlid Fish Oreochromis (Alcolapia) alcalica

Although it is widely accepted that the cellular and molecular mechanisms of vertebrate cardiac development are evolutionarily conserved, this is on the basis of data from only a few model organisms suited to laboratory studies. Here, we investigate gene expression during cardiac development in the extremophile, non-model fish species, Oreochromis (Alcolapia) alcalica. We first characterise the early development of O. alcalica and observe extensive vascularisation across the yolk prior to hatching. We further investigate heart development by identifying and cloning O. alcalica orthologues of conserved cardiac transcription factors gata4, tbx5, and mef2c for analysis by in situ hybridisation. Expression of these three key cardiac developmental regulators also reveals other aspects of O. alcalica development, as these genes are expressed in developing blood, limb, eyes, and muscle, as well as the heart. Our data support the notion that O. alcalica is a direct-developing vertebrate that shares the highly conserved molecular regulation of the vertebrate body plan. However, the expression of gata4 in O. alcalica reveals interesting differences in the development of the circulatory system distinct from that of the well-studied zebrafish. Understanding the development of O. alcalica embryos is an important step towards providing a model for future research into the adaptation to extreme conditions; this is particularly relevant given that anthropogenic-driven climate change will likely result in more freshwater organisms being exposed to less favourable conditions.

Acute fluorene-9-bisphenol exposure damages early development and induces cardiotoxicity in zebrafish (Danio rerio)

Fluorene-9-bisphenol (BHPF) is a substitute for bisphenol A (BPA), which is widely used to manufacture plastic products. Previous studies indicate that BHPF has an anti-estrogenic effect and induces cytotoxicity in mice oocytes. However, the effects of acute BHPF exposure on the aquatic organism obtain little attention. In this study, a series of BHPF concentrations (1 μM, 2 μM, 5 μM, 10 μM, 20 μM) was used to exposed zebrafish embryos from 2 h post-fertilization (hpf). The results showed the LC₅₀ at 96hpf was 2.88 μM (1.01 mg/L). Acute exposure induced malformation in morphology, and retarded epiboly rate at 10hpf, increased apoptosis. Moreover, acute BHPF exposure led cardiotoxicity, by impeding cardiac looping, decreasing cardiac contractility (reducing the stroke volume and cardiac output, decreasing fractional shortening of ventricle). Besides that, BHPF exposure altered the expression of cardiac transcriptional regulators and development related genes. In conclusion, acute BHPF exposure induced developmental abnormality, retarded cardiac morphogenesis and injured the cardiac contractility. This study indicated BHPF would be an unneglected threat for the safety of aquatic organisms.

Exposure to the AhR agonist cyprodinil impacts the cardiac development and function of zebrafish larvae

Cyprodinil is a broad-spectrum pyrimidine amine fungicide that has been reportedly used worldwide. However, toxicity studies of cyprodinil on aquatic organisms, specifically zebrafish (Danio rerio), are lacking. In our present study, we predicted cyprodinil binding to the aryl hydrocarbon receptor (AhR) by using molecular docking simulation. Then, we used recombinant HepG2 cells and Tg(cyp1a1-12DRE:egfp) transgenic zebrafish to further assess the AhR agonistic activity of cyprodinil. Besides, the significant upregulation of cyp1a1 further verified that statement. Moreover, we found that zebrafish exposure to cyprodinil induced developmental toxicity in the larvae, particularly during cardiac development. The expression levels of cardiac development-related genes, namely tbx5, nkx2.5, gata4, and tnnt2, were markedly altered, which might cause the adverse effects of cyprodinil on cardiac function and development. In summary, we found that cyprodinil, as an AhR agonist, induced development toxicity in zebrafish larvae, especially on cardiac. Data here can assess the potential effects on organisms in the aquatic environment and promote the regulation and safe use of cyprodinil.

Pioneer Transcription Factors Initiating Gene Network Changes

Pioneer transcription factors have the intrinsic biochemical ability to scan partial DNA sequence motifs that are exposed on the surface of a nucleosome and thus access silent genes that are inaccessible to other transcription factors. Pioneer factors subsequently enable other transcription factors, nucleosome remodeling complexes, and histone modifiers to engage chromatin, thereby initiating the formation of an activating or repressive regulatory sequence. Thus, pioneer factors endow the competence for fate changes in embryonic development, are essential for cellular reprogramming, and rewire gene networks in cancer cells. Recent studies with reconstituted nucleosomes in vitro and chromatin binding in vivo reveal that pioneer factors can directly perturb nucleosome structure and chromatin accessibility in different ways. This review focuses on our current understanding of the mechanisms by which pioneer factors initiate gene network changes and will ultimately contribute to our ability to control cell fates at will.

Exposure to pyrimethanil induces developmental toxicity and cardiotoxicity in zebrafish

Pyrimethanil is a broad-spectrum fungicide commonly used in the prevention and treatment of Botrytis cinerea. However, little information is available in the literature to show the toxicity of Pyrimethanil to cardiac development. In this study, we used an experimental animal model to explore the developmental and cardiac toxicity of Pyrimethanil in aquatic vertebrates; we exposed zebrafish embryos to Pyrimethanil at concentrations of 2, 4, and 6 mg/L from 5.5 to 72 h post fertilisation. We found that Pyrimethanil caused a decrease in the hatching rate, heart rate, and survival rate of zebrafish embryos. Pyrimethanil exposure also resulted in pericardial and yolk sac edema, spinal deformity, and heart loop failure. Moreover, Pyrimethanil increased reactive oxygen stress levels and heightened the activity of superoxide dismutase and catalase. Alterations were induced in the transcription of apoptosis-related genes (p53, Bax, Bcl2, Casp 9, and Casp6l1) and heart development-related genes (Tbx2b, Gata4, Myh6, Vmhc, Nppa, Bmp2b, Bpm 4, and Bpm 10). Our data showed that the activation of Wnt signalling by BML-284 could partially rescue the malformed phenotype caused by Pyrimethanil. Our results provide new evidence for Pyrimethanil's toxicity and the danger of its residues in the environment and agricultural products.

Exposure to prothioconazole induces developmental toxicity and cardiovascular effects on zebrafish embryo

Prothioconazole is a fungicide that has been widely used in general agriculture and livestock husbandry. This study evaluated the acute toxicity of prothioconazole to zebrafish embryos by assessing their hatching rate and malformation when exposed to different concentrations of prothioconazole. The 96 h-LC₅₀ value of zebrafish embryos was 1.70 mg/L. Upon exposure to 0.85 mg/L, the mortality rate of the embryos significantly increased while their hatching rate decreased significantly. At prothioconazole concentrations higher than 0.43 mg/L, developmental morphologic abnormalities such as heart and yolk-sac edema, spine curvature, tail deformity, shortened body length and decreased eye area were observed. The heart rate of embryos decreased in a dose-dependent fashion during the exposure time. Prothioconazole exposure also resulted in increased rates of cardiac malformation detected by significant increase in the distance between the sinus venosus and bulbus arteriosus and the pericardium area. Moreover, the expression levels of genes related to cardiac development (amhc, vmhc, fli1, hand2, gata4, nkx2.5, tbx5 and atp2a2a) were significantly altered after exposure to prothioconazole. Indeed, this study revealed the adverse effects on the developmental and cardiovascular system of zebrafish embryo caused by prothioconazole. It further elucidated the risk of prothioconazole exposure to vertebrate cardiovascular toxicity. As such, it provides a theoretical foundation for pesticide risk management measures.

α-asarone induces cardiac defects and QT prolongation through mitochondrial apoptosis pathway in zebrafish

α-asarone is a natural phenylpropene found in several plants, which are widely used for flavoring foods and treating diseases. Previous studies have demonstrated that α-asarone has many pharmacological functions, while some reports indicated its toxicity. However, little is known about its cardiovascular effects. This study investigated developmental toxicity of α-asarone in zebrafish, especially the cardiotoxicity. Zebrafish embryos were exposed to different concentrations of α-asarone (1, 3, 5, 10, and 30 μM). Developmental toxicity assessments revealed that α-asarone did not markedly affect mortality and hatching rate. In contrast, there was a concentration-dependent increase in malformation rate of zebrafish treated with α-asarone. The most representative cardiac defects were increased heart malformation rate, pericardial edema areas, sinus venosus-bulbus arteriosus distance, and decreased heart rate. Notably, we found that α-asarone impaired the cardiac function of zebrafish by prolonging the mean QTc duration and causing T-wave abnormalities. The expressions of cardiac development-related key transcriptional regulators tbx5, nkx2.5, hand2, and gata5 were all changed under α-asarone exposure. Further investigation addressing the mechanism indicated that α-asarone triggered apoptosis mainly in the heart region of zebrafish. Moreover, the elevated expression of puma, cyto C, afap1, caspase 3, and caspase 9 in treated zebrafish suggested that mitochondrial apoptosis is likely to be the main reason for α-asarone induced cardiotoxicity. These findings revealed the cardiac developmental toxicity of α-asarone, expanding our knowledge about the toxic effect of α-asarone on living organisms.

A tumor suppressor enhancing module orchestrated by GATA4 denotes a therapeutic opportunity for GATA4 deficient HCC patients

Rationale: Effective targeting therapies are limited in Hepatocellular carcinoma (HCC) clinic. Characterization of tumor suppressor genes (TSGs) and elucidation their signaling cascades could shed light on new strategies for developing targeting therapies for HCC.

Methods: We checked genome-wide DNA copy number variation (CNV) of HCC samples, focusing on deleted genes for TSG candidates. Clinical data, in vitro and in vivo data were collected to validate the tumor suppressor functions.

Results: Focal deletion of GATA4 gene locus was the most prominent feature across all liver cancer samples. Ectopic expression of GATA4 resulted in senescence of HCC cell lines. Mechanistically, GATA4 exerted tumor suppressive role by orchestrating the assembly of a tumor suppressor enhancing module: GATA4 directly bound and potently inhibited the mRNA transcription activity of β-catenin; meanwhile, β-catenin was recruited by GATA4 to promoter regions and facilitated transcription of GATA4 target genes, which were TSGs per se. Expression of GATA4 was effective to shrink GATA4-deficient HCC tumors in vivo. We also showed that β-catenin inhibitor was capable of shrinking GATA4-deficient tumors.

Conclusions: Our study unveiled a previously unnoticed tumor suppressor enhancing module assembled by ectopically expressed GATA4 in HCC cells and denoted a therapeutic opportunity for GATA4 deficient HCC patients. Our study also presented an interesting case that an oncogenic transcription factor conditionally functioned as a tumor suppressor when recruited by a TSG transcription factor.

The roles and controls of GATA factors in blood and cardiac development

GATA factors play central roles in the programming of blood and cardiac cells during embryonic development. Using the experimentally accessible Xenopus and zebrafish models, we report observations regarding the roles of GATA‐2 in the development of blood stem cells and GATA‐4, ‐5, and ‐6 in cardiac development. We show that blood stem cells develop from the dorsal lateral plate mesoderm and GATA‐2 is required at multiple stages. Firstly, GATA‐2 is required to make the cells responsive to VEGF‐A signalling by driving the synthesis of its receptor, FLK‐1/KDR. This leads to differentiation into the endothelial cells that form the dorsal aorta. GATA‐2 is again required for the endothelial‐to‐haematopoietic transition that takes place later in the floor of the dorsal aorta. GATA‐2 expression is dependent on BMP signalling for each of these inputs into blood stem cell programming. GATA‐4, ‐5, and ‐6 work together to ensure the specification of cardiac cells during development. We have demonstrated redundancy within the family and also some evolution of the functions of the different family members. Interestingly, one of the features that varies in evolution is the timing of expression relative to other key regulators such as Nkx2.5 and BMP. We show that the GATA factors, Nkx2.5 and BMP regulate each other and it would appear that what is critical is the mutually supportive network of expression rather than the order of expression of each of the component genes. In Xenopus and zebrafish, the cardiac mesoderm is adjacent to an anterior population of cells giving rise to blood and endothelium. This population is not present in mammals and we have shown that, like the cardiac population, the blood and endothelial precursors require GATA‐4, ‐5, and ‐6 for their development. Later, blood‐specific or cardiac‐specific regulators determine the ultimate fate of the cells, and we show that these regulators act cross‐antagonistically. Fibroblast growth factor (FGF) signalling drives the cardiac fate, and we propose that the anterior extension of the FGF signalling field during evolution led to the recruitment of the blood and endothelial precursors into the heart field ultimately resulting in a larger four chambered heart. Zebrafish are able to successfully regenerate their hearts after injury. To understand the pathways involved, with a view to determining why humans cannot do this, we profiled gene expression in the cardiomyocytes before and after injury, and compared those proximal to the injury with those more distal. We were able to identify an enhancement of the expression of regulators of the canonical Wnt pathway proximal to the injury, suggesting that changes in Wnt signalling are responsible for the repair response to injury.

Exposure to low-level metalaxyl impacts the cardiac development and function of zebrafish embryos

Metalaxyl is an anilide pesticide that is widely used to control plant diseases caused by Peronosporales species. In order to study the toxic effects, zebrafish embryos were exposed to metalaxyl at nominal concentrations of 5, 50 and 500 ng/L for 72 hr, and the cardiac development and functioning of larvae were observed. The results showed that metalaxyl exposure resulted in increased rates of pericardial edema, heart hemorrhage and cardiac malformation. The distance between the sinus venosus and bulbus arteriosus, stroke volume, cardiac output and heart rate were significantly increased in larvae exposed to 50 and 500 ng/L metalaxyl compared to solvent control larvae. Significant upregulation in the transcription of tbx5, gata4 and myh6 was observed in the 50 and 500 ng/L treatments, and that of nkx2.5 and myl7 was observed in the 5, 50 and 500 ng/L groups. These disturbances may be related to cardiac developmental and functional defects in the larvae. The activity of Na⁺/K⁺-ATPase and Ca²⁺-ATPase was significantly increased in zebrafish embryos exposed to 500 ng/L metalaxyl, and the mRNA levels of genes related to ATPase (atp2a11, atp1b2b, and atp1a3b) (in the 50 and 500 ng/L groups) and calcium channels (cacna1ab) (in the 500 ng/L group) were significantly downregulated; these changes might be associated with heart arrhythmia and functional failure.

Context-Specific Transcription Factor Functions Regulate Epigenomic and Transcriptional Dynamics during Cardiac Reprogramming

Ectopic expression of combinations of transcription factors (TFs) can drive direct lineage conversion, thereby reprogramming a somatic cell's identity. To determine the molecular mechanisms by which Gata4, Mef2c, and Tbx5 (GMT) induce conversion from a cardiac fibroblast toward an induced cardiomyocyte, we performed comprehensive transcriptomic, DNA-occupancy, and epigenomic interrogation throughout the reprogramming process. Integration of these datasets identified new TFs involved in cardiac reprogramming and revealed context-specific roles for GMT, including the ability of Mef2c and Tbx5 to independently promote chromatin remodeling at previously inaccessible sites. We also find evidence for cooperative facilitation and refinement of each TF's binding profile in a combinatorial setting. A reporter assay employing newly defined regulatory elements confirmed that binding of a single TF can be sufficient for gene activation, suggesting that co-binding events do not necessarily reflect synergy. These results shed light on fundamental mechanisms by which combinations of TFs direct lineage conversion.

Fenbuconazole exposure impacts the development of zebrafish embryos

Fenbuconazole (FBZ), a triazole-containing fungicide, is widely used in agriculture and horticulture. In the present study, the development and cardiac functioning were observed and determined in zebrafish embryos exposed to FBZ at 5, 50 and 500 ng/L nominal concentrations for 72 h. The results showed that 500 ng/L FBZ significantly increased pericardial edema rate, spine curvature rate, disturbed cardiac function, and led a shortened lower jaw. The transcription of genes such as tbx5, nkx2.5, tnnt2, gata4, bmp2b, myl7 was altered, which might be responsible for the cardiac developmental and functioning defects in the larvae. The deformation in bone development might be related with the impaired transcription levels of shh and bmp2b. The transcription of cyp26a1 (encoding retinoic acid metabolism enzyme) was significantly up-regulated in the 500 ng/L group, which might be a reason causing the teratogenic effect of FBZ. These results suggest that FBZ could have toxic effects on embryonic development, which should be considered in the risk evaluation of FBZ application.

Epigenetic Regulation in Prostate Cancer Progression

Purpose of Review

An important number of newly identified molecular alterations in prostate cancer affect gene encoding master regulators of chromatin biology epigenetic regulation. This review will provide an updated view of the key epigenetic mechanisms underlying prostate cancer progression, therapy resistance, and potential actionable mechanisms and biomarkers.

Recent Findings

Key players in chromatin biology and epigenetic master regulators has been recently described to be crucially altered in metastatic CRPC and tumors that progress to AR independency. As such, epigenetic dysregulation represents a driving mechanism in the reprograming of prostate cancer cells as they lose AR-imposed identity.

Summary

Chromatin integrity and accessibility for transcriptional regulation are key features altered in cancer progression, and particularly relevant in nuclear hormone receptor-driven tumors like prostate cancer. Understanding how chromatin remodeling dictates prostate development and how its deregulation contributes to prostate cancer onset and progression may improve risk stratification and treatment selection for prostate cancer patients.

GATA4 is a transcriptional regulator of R-spondin1 in Japanese flounder (Paralichthys olivaceus)

GATA4 is a well-known transcription factor of the GATA family implicated in regulation of sex determination and gonadal development in mammals. In this study, we cloned the full-length cDNA of Paralichthys olivaceus gata4 (Po-gata4). Phylogenetic, gene structure, and synteny analysis showed that Po-GATA4 is homologous to GATA4 of teleost and tetrapod. Po-gata4 transcripts were detected in Sertoli cells, spermatogonia, oogonia and oocytes, with higher transcript levels overall in the testis than the ovary. The promoter region of P. olivaceus R-spondin1was found to contain a GATA4-binding motif. Results of CBA (cleaved amplified polymorphic sequence-based binding assay) indicated that GATA4 could indeed bind to the promoter sequence of R-spondin1. Moreover, human GATA4 recombinant protein could upregulate R-spondin1 in P. olivaceus ovary cells and FBCs (flounder brain cell line). In FBCs, overexpression of Po-gata4 resulted in elevated transcript levels of R-spondin1. Taken together, our results indicate that Po-GATA4 is involved in gonadal development by regulating R-spondin1 expression.

GATA4 as a novel regulator involved in the development of the neural crest and craniofacial skeleton via Barx1

The role of GATA-binding protein 4 (GATA4) in neural crest cells (NCCs) is poorly defined. Here we showed that mouse NCCs lacking GATA4 exhibited developmental defects in craniofacial bone, teeth, and heart. The defects likely occurred due to decreased cell proliferation at the developmental stage. The in vitro results were consistent with the mouse model. The isobaric tags for relative and absolute quantitation assay revealed that BARX1 is one of the differentially expressed proteins after GATA4 knockdown in NCCs. On the basis of the results of dual-luciferase, electro-mobility shift, and chromatin immunoprecipitation assays, Barx1 expression is directly regulated by GATA4 in NCCs. In zebrafish, gata4 knockdown affects the development of NCCs derivatives. However, the phenotype in zebrafish could be partly rescued by co-injection of gata4 morpholino oligomers and barx1 mRNA. This study identified new downstream targets of GATA4 in NCCs and uncovered additional evidence of the complex regulatory functions of GATA4 in NCC development.

Pioneer transcription factors shape the epigenetic landscape

Pioneer transcription factors have the unique and important role of unmasking chromatin domains during development to allow the implementation of new cellular programs. Compared with those of other transcription factors, this activity implies that pioneer factors can recognize their target DNA sequences in so-called compacted or "closed" heterochromatin and can trigger remodeling of the adjoining chromatin landscape to provide accessibility to nonpioneer transcription factors. Recent studies identified several steps of pioneer action, namely rapid but weak initial binding to heterochromatin and stabilization of binding followed by chromatin opening and loss of cytosine-phosphate-guanine (CpG) methylation that provides epigenetic memory. Whereas CpG demethylation depends on replication, chromatin opening does not. In this Minireview, we highlight the unique properties of this transcription factor class and the challenges of understanding their mechanism of action.

The developmental effects of low-level procymidone towards zebrafish embryos and involved mechanism

Procymidone (PCM), a dicarboximide fungicide, is widely used in agriculture to control plant diseases. In the present study, zebrafish embryos were exposed to PCM at 0, 10, 100 and 1000 ng/L for 72 h, the development and cardiac functioning of larvae were observed and determined. The results showed that hatching rate was significantly decreased in the 1000 ng/L treatment, and pericardial edema rate and spine curvature rate were significantly increased in the 100 and 1000 ng/L groups. The PCM-treated larvae exhibited an increased heart rate as well as arrhythmia, and shortened low jaw. The transcription levels of cardiac development-related genes tbx5, nkx2.5, tnnt2, gata4, myh6, myl7, cdh2, ryr2 were altered, which might be responsible for the cardiac developmental and functioning defects in the larvae. The deformation in bone development might be related with the impaired transcription levels of ihh, shh, bmp2b, bmp4, gh, igf1, sox9, gli2. The activities of Na⁺/K⁺-ATPase and Ca²⁺-ATPase were significantly inhibited by 100 ng/L and 1000 ng/L PCM exposure, which might be a cause for the occurrence of pericardial edema and skeletal deformation. The results of this study will be helpful in evaluating the potential threat of PCM to fish population in the aquatic environment.

Heart function and thoracic aorta gene expression profiling studies of ginseng combined with different herbal medicines in eNOS knockout mice

Ginseng, a popular herbal remedy, is often used in combination with other drugs to achieve the maximum therapeutic response. Shenfu (SFI) and Shenmai injection (SMI) have been widely used to treat cardiovascular disease in China. Our study explored the cardiovascular protection of SFI and SMI in eNOS knockout mice to investigate the differences and similarities of the two ginseng-combinations. Transthoracic echocardiography was performed to evaluate the left ventricular structure and function at baseline and 3, 7, and 14 days after drug administration. Agilent Gene Expression microarrays were used to demonstrate the gene expression profiling of the thoracic aorta. Ingenuity Pathway Analysis was performed to evaluate the mechanism improved by SFI and SMI in eNOS knockout mice. Both SFI and SMI could modulate Gadd45 Signaling from TOP15 canonical pathways. Moreover, SFI showed a better effect in the early treatment stage and improved myocardial function via GATA4, GATA6 and COL3A1. Meanwhile, SMI exerted better protective effects at the chronic stage, which may be related to endothelium protection by VEGFA and ACE. The advantage of multi-target by drug combination in progression of complex diseases should be noticed. The appropriate adjustment of drug combination could lead to a better accurate medical care in clinic.

In vivo cardiovascular toxicity induced by acetochlor in zebrafish larvae

The risk of acetochlor to human health is still unclear, prompting concern over its risk, especially to pesticide suicides population, occupational population (farmers, retailers and pharmaceutical workers), and special population (young children and infants, pregnant women, older people, and those with compromised immune systems). This study was to explore the toxic effect and the possible mechanism of toxic action of acetochlor using zebrafish larvae whose toxicity profiles have been confirmed to be strikingly similar with mammalian. The result indicated that the toxic target organ of acetochlor was cardiovascular system. Thus, cardiovascular toxicity evaluation was investigated systematically. The main phenotypes of cardiovascular toxicity induced by acetochlor were bradycardia, pericardial edema, circulation defect, and thrombosis; Malformed heart was confirmed by histopathological examination. Thrombosis which maybe triggered by bradycardia was further studied using o-dianisidine for erythrocyte staining; Substantial thrombus in the caudal vein and significantly reduced heart red blood cells (RBCs) intensity which can reflect the thrombosis degree were observed in zebrafish in a concentration-dependent manner. Additionally, the mRNA expression level of Nkx2.5 and Gata4 related to induction of cardiac program were down-regulated significantly by quantitative real-time polymerase chain reaction (qRT-PCR), which could cause defects in the cardiovascular system. For the first time, our results demonstrated that acetochlor induced cardiovascular toxicity, and down-regulation of Nkx2.5 and Gata4 might be its possible molecular basis. Our data generated here might provide novel insights into cardiovascular disease risk following acetochlor exposure to human, especially to pesticide suicides population, occupational population and special population.

GATA6 is essential for endoderm formation from human pluripotent stem cells

Protocols have been established that direct differentiation of human pluripotent stem cells into a variety of cell types, including the endoderm and its derivatives. This model of differentiation has been useful for investigating the molecular mechanisms that guide human developmental processes. Using a directed differentiation protocol combined with shRNA depletion we sought to understand the role of GATA6 in regulating the earliest switch from pluripotency to definitive endoderm. We reveal that GATA6 depletion during endoderm formation results in apoptosis of nascent endoderm cells, concomitant with a loss of endoderm gene expression. We show by chromatin immunoprecipitation followed by DNA sequencing that GATA6 directly binds to several genes encoding transcription factors that are necessary for endoderm differentiation. Our data support the view that GATA6 is a central regulator of the formation of human definitive endoderm from pluripotent stem cells by directly controlling endoderm gene expression.

Summary: Using the differentiation of huESCs as a model for endoderm formation, we reveal that the transcription factor GATA6 regulates the onset of endoderm gene expression and is required for its viability.

Partially compromised specification causes stochastic effects on gut development in C. elegans

The C. elegans gut descends from the E progenitor cell through a series of stereotyped cell divisions and morphogenetic events. Effects of perturbations of upstream cell specification on downstream organogenesis have not been extensively investigated. Here we have assembled an allelic series of strains that variably compromise specification of E by perturbing the activation of the gut-specifying end-1 and end-3 genes. Using a marker that allows identification of all E descendants regardless of fate, superimposed with markers that identify cells that have adopted a gut fate, we have examined the fate of E lineage descendants among hundreds of embryos. We find that when specification is partially compromised, the E lineage undergoes hyperplasia accompanied by stochastic and variable specification of gut fate among the E descendants. As anticipated by prior work, the activation of the gut differentiation factor elt-2 becomes delayed in these strains, although ultimate protein levels of a translational ELT-2::GFP reporter resemble those of the wild type. By comparing these effects among the various specification mutants, we find that the stronger the defect in specification (i.e. the fewer number of embryos specifying gut), the stronger the defects in the E lineage and delay in activation of elt-2. Despite the changes in the E lineage in these strains, we find that supernumerary E descendants that adopt a gut fate are accommodated into a relatively normal-looking intestine. Hence, upstream perturbation of specification dramatically affects the E lineage, but as long as sufficient descendants adopt a gut fate, organogenesis overcomes these effects to form a relatively normal intestine.

GATA6 Plays an Important Role in the Induction of Human Definitive Endoderm, Development of the Pancreas, and Functionality of Pancreatic β Cells

Induced pluripotent stem cells were created from a pancreas agenesis patient with a mutation in GATA6. Using genome-editing technology, additional stem cell lines with mutations in both GATA6 alleles were generated and demonstrated a severe block in definitive endoderm induction, which could be rescued by re-expression of several different GATA family members. Using the endodermal progenitor stem cell culture system to bypass the developmental block at the endoderm stage, cell lines with mutations in one or both GATA6 alleles could be differentiated into β-like cells but with reduced efficiency. Use of suboptimal doses of retinoic acid during pancreas specification revealed a more severe phenotype, more closely mimicking the patient’s disease. GATA6 mutant β-like cells fail to secrete insulin upon glucose stimulation and demonstrate defective insulin processing. These data show that GATA6 plays a critical role in endoderm and pancreas specification and β-like cell functionality in humans.

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GATA6 is required for definitive endoderm specification in human ES/iPS cells

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Bypassing the endoderm defect allows GATA6 mutants to generate β-like cells

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Suboptimal retinoic acid signaling blocks pancreas specification in GATA6 mutants

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GATA6 is critical for human β cell function in vitro