Mouse GATA-4: a retinoic acid-inducible GATA-binding transcription factor expressed in endodermally derived tissues and heart

Retinoic Acid Promotes the In Vitro Growth, Patterning and Improves the Cellular Composition of Human Pluripotent Stem-Cell-Derived Intestinal Organoids

Human intestinal organoids (HIOs) generated from human pluripotent stem cells hold great promise for modeling human development and as a possible source of tissue for transplantation. HIOs generate all of the main epithelial and mesenchymal cell types found in the developing human intestine and mature into intestinal tissue with crypts and villi following transplantation into immunocompromised mice. However, incomplete in vitro patterning and the presence of contaminating neurons could hinder their use for regenerative medicine in humans. Based on studies in model organisms, we hypothesized that the treatment of HIOs with all trans retinoic acid (ATRA) would improve their in vitro growth and patterning. We found that ATRA not only improved the patterning of HIOs, ATRA also increased organoid forming efficiency, improved epithelial growth, enriched intestinal subepithelial myofibroblasts (ISEMFs) and reduced neuronal contamination in HIOs. Taken together, our studies demonstrate how the manipulation of a single developmental signaling pathway can be used to improve the survival, patterning and cellular composition of HIOs.

HOPX Plays a Critical Role in Antiretroviral Drugs Induced Epigenetic Modification and Cardiac Hypertrophy

People living with HIV (PLWH) have to take an antiretroviral therapy (ART) for life and show noncommunicable illnesses such as chronic inflammation, immune activation, and multiorgan dysregulation. Recent studies suggest that long-term use of ART induces comorbid conditions and is one of the leading causes of heart failure in PLWH. However, the molecular mechanism of antiretroviral drugs (ARVs) induced heart failure is unclear. To determine the mechanism of ARVs induced cardiac dysfunction, we performed global transcriptomic profiling of ARVs treated neonatal rat ventricular cardiomyocytes in culture. Differentially expressed genes were identified by RNA-sequencing. Our data show that ARVs treatment causes upregulation of several biological functions associated with cardiotoxicity, hypertrophy, and heart failure. Global gene expression data were validated in cardiac tissue isolated from HIV patients having a history of ART. Interestingly, we found that homeodomain-only protein homeobox (HOPX) expression was significantly increased in cardiomyocytes treated with ARVs and in the heart tissue of HIV patients. Furthermore, we found that HOPX plays a crucial role in ARVs mediated cellular hypertrophy. Mechanistically, we found that HOPX plays a critical role in epigenetic regulation, through deacetylation of histone, while the HDAC inhibitor, Trichostatin A, can restore the acetylation level of histone 3 in the presence of ARVs.

Comparison of Differentiation Pattern and WNT/SHH Signaling in Pluripotent Stem Cells Cultured under Different Conditions

Pluripotent stem cells (PSCs) are characterized by the ability to self-renew as well as undergo multidirectional differentiation. Culture conditions have a pivotal influence on differentiation pattern. In the current study, we compared the fate of mouse PSCs using two culture media: (1) chemically defined, free of animal reagents, and (2) standard one relying on the serum supplementation. Moreover, we assessed the influence of selected regulators (WNTs, SHH) on PSC differentiation. We showed that the differentiation pattern of PSCs cultured in both systems differed significantly: cells cultured in chemically defined medium preferentially underwent ectodermal conversion while their endo- and mesodermal differentiation was limited, contrary to cells cultured in serum-supplemented medium. More efficient ectodermal differentiation of PSCs cultured in chemically defined medium correlated with higher activity of SHH pathway while endodermal and mesodermal conversion of cells cultured in serum-supplemented medium with higher activity of WNT/JNK pathway. However, inhibition of either canonical or noncanonical WNT pathway resulted in the limitation of endo- and mesodermal conversion of PSCs. In addition, blocking WNT secretion led to the inhibition of PSC mesodermal differentiation, confirming the pivotal role of WNT signaling in this process. In contrast, SHH turned out to be an inducer of PSC ectodermal, not mesodermal differentiation.

Transcription Control of Liver Development

During liver organogenesis, cellular transcriptional profiles are constantly reshaped by the action of hepatic transcriptional regulators, including FoxA1-3, GATA4/6, HNF1α/β, HNF4α, HNF6, OC-2, C/EBPα/β, Hex, and Prox1. These factors are crucial for the activation of hepatic genes that, in the context of compact chromatin, cannot access their targets. The initial opening of highly condensed chromatin is executed by a special class of transcription factors known as pioneer factors. They bind and destabilize highly condensed chromatin and facilitate access to other "non-pioneer" factors. The association of target genes with pioneer and non-pioneer transcription factors takes place long before gene activation. In this way, the underlying gene regulatory regions are marked for future activation. The process is called "bookmarking", which confers transcriptional competence on target genes. Developmental bookmarking is accompanied by a dynamic maturation process, which prepares the genomic loci for stable and efficient transcription. Stable hepatic expression profiles are maintained during development and adulthood by the constant availability of the main regulators. This is achieved by a self-sustaining regulatory network that is established by complex cross-regulatory interactions between the major regulators. This network gradually grows during liver development and provides an epigenetic memory mechanism for safeguarding the optimal expression of the regulators.

Maternal iron deficiency perturbs embryonic cardiovascular development in mice

Congenital heart disease (CHD) is the most common class of human birth defects, with a prevalence of 0.9% of births. However, two-thirds of cases have an unknown cause, and many of these are thought to be caused by in utero exposure to environmental teratogens. Here we identify a potential teratogen causing CHD in mice: maternal iron deficiency (ID). We show that maternal ID in mice causes severe cardiovascular defects in the offspring. These defects likely arise from increased retinoic acid signalling in ID embryos. The defects can be prevented by iron administration in early pregnancy. It has also been proposed that teratogen exposure may potentiate the effects of genetic predisposition to CHD through gene-environment interaction. Here we show that maternal ID increases the severity of heart and craniofacial defects in a mouse model of Down syndrome. It will be important to understand if the effects of maternal ID seen here in mice may have clinical implications for women.

iPSC Modeling of RBM20-Deficient DCM Identifies Upregulation of RBM20 as a Therapeutic Strategy

Recent advances in induced pluripotent stem cell (iPSC) technology and directed differentiation of iPSCs into cardiomyocytes (iPSC-CMs) make it possible to model genetic heart disease in vitro. We apply CRISPR/Cas9 genome editing technology to introduce three RBM20 mutations in iPSCs and differentiate them into iPSC-CMs to establish an in vitro model of RBM20 mutant dilated cardiomyopathy (DCM). In iPSC-CMs harboring a known causal RBM20 variant, the splicing of RBM20 target genes, calcium handling, and contractility are impaired consistent with the disease manifestation in patients. A variant (Pro633Leu) identified by exome sequencing of patient genomes displays the same disease phenotypes, thus establishing this variant as disease causing. We find that all-trans retinoic acid upregulates RBM20 expression and reverts the splicing, calcium handling, and contractility defects in iPSC-CMs with different causal RBM20 mutations. These results suggest that pharmacological upregulation of RBM20 expression is a promising therapeutic strategy for DCM patients with a heterozygous mutation in RBM20.

Briganti et al. use iPSC and CRISPR/Cas9 to create a model of RBM20-deficient dilated cardiomyopathy (DCM) that recapitulates mRNA splicing and contractile defects of the disease. They evaluate pharmacological upregulation of RBM20 as a therapeutic strategy. All-trans retinoic acid upregulates RBM20 expression and ameliorates the in vitro hallmarks of disease.

From Stripes to a Beating Heart: Early Cardiac Development in Zebrafish

The heart is the first functional organ to form during vertebrate development. Congenital heart defects are the most common type of human birth defect, many originating as anomalies in early heart development. The zebrafish model provides an accessible vertebrate system to study early heart morphogenesis and to gain new insights into the mechanisms of congenital disease. Although composed of only two chambers compared with the four-chambered mammalian heart, the zebrafish heart integrates the core processes and cellular lineages central to cardiac development across vertebrates. The rapid, translucent development of zebrafish is amenable to in vivo imaging and genetic lineage tracing techniques, providing versatile tools to study heart field migration and myocardial progenitor addition and differentiation. Combining transgenic reporters with rapid genome engineering via CRISPR-Cas9 allows for functional testing of candidate genes associated with congenital heart defects and the discovery of molecular causes leading to observed phenotypes. Here, we summarize key insights gained through zebrafish studies into the early patterning of uncommitted lateral plate mesoderm into cardiac progenitors and their regulation. We review the central genetic mechanisms, available tools, and approaches for modeling congenital heart anomalies in the zebrafish as a representative vertebrate model.

Generation of cell-permeant recombinant human transcription factor GATA4 from E. coli

Transcription factor GATA4 is expressed during early embryogenesis and is vital for proper development. In addition, it is a crucial reprogramming factor for deriving functional cardiomyocytes and was recently identified as a tumor suppressor protein in various cancers. To generate a safe and effective molecular tool that can potentially be used in a cell reprogramming process and as an anti-cancer agent, we have identified optimal expression parameters to obtain soluble expression of human GATA4 in E. coli and purified the same to homogeneity under native conditions using immobilized metal ion affinity chromatography. The identity of GATA4 protein was confirmed using western blotting and mass spectrometry. Using circular dichroism spectroscopy, it was demonstrated that the purified recombinant protein has maintained its secondary structure, primarily comprising of random coils and α-helices. Subsequently, this purified recombinant protein was applied to human cells and was found that it was non-toxic and able to enter the cells as well as translocate to the nucleus. Prospectively, this cell- and nuclear-permeant molecular tool is suitable for cell reprogramming experiments and can be a safe and effective therapeutic agent for cancer therapy.

The role of HOPX in normal tissues and tumor progression

The homeodomain-only protein homeobox (HOPX) as the smallest homeodomain protein, lacks certain conserved residues required for DNA binding. Through our literature search, we reviewed the current understandings of HOPX in normal tissues and tumor progression. HOPX was initially identified as a critical transcription factor in various normal tissues, which interacted with serum response factor (SRF) or other substance to regulate normal physiological function. However, HOPX is at a low expression or methylation level in tumors. These data indicated that HOPX may play a very important role in regulating differentiation phenotype and tumor suppressive function. We predicted the prognosis of HOPX in tumors from TCGA database and discussed the downstream genes of HOPX. To understand how HOPX is involved in the mechanisms between physical and pathological conditions could lead to novel therapeutic strategies for treatment.

Deacetylase-independent function of SIRT6 couples GATA4 transcription factor and epigenetic activation against cardiomyocyte apoptosis

SIRT6 deacetylase activity improves stress resistance via gene silencing and genome maintenance. Here, we reveal a deacetylase-independent function of SIRT6, which promotes anti-apoptotic gene expression via the transcription factor GATA4. SIRT6 recruits TIP60 acetyltransferase to acetylate GATA4 at K328/330, thus enhancing its chromatin binding capacity. In turn, GATA4 inhibits the deacetylase activity of SIRT6, thus ensuring the local chromatin accessibility via TIP60-promoted H3K9 acetylation. Significantly, the treatment of doxorubicin (DOX), an anti-cancer chemotherapeutic, impairs the SIRT6-TIP60-GATA4 trimeric complex, blocking GATA4 acetylation and causing cardiomyocyte apoptosis. While GATA4 hyperacetylation-mimic retains the protective effect against DOX, the hypoacetylation-mimic loses such ability. Thus, the data reveal a novel SIRT6-TIP60-GATA4 axis, which promotes the anti-apoptotic pathway to prevent DOX toxicity. Targeting the trimeric complex constitutes a new strategy to improve the safety of DOX chemotherapy in clinical application.

Krüppel-like factor 17 upregulates uterine corin expression and promotes spiral artery remodeling in pregnancy

Spiral artery remodeling is an important physiological process in the pregnant uterus which increases blood flow to the fetus. Impaired spiral artery remodeling contributes to preeclampsia, a major disease in pregnancy. Corin, a transmembrane serine protease, is up-regulated in the pregnant uterus to promote spiral artery remodeling. To date, the mechanism underlying uterine corin up-regulation remains unknown. Here we show that Krüppel-like factor (KLF) 17 is a key transcription factor for uterine corin expression in pregnancy. In cultured human uterine endometrial cells, KLF17 binds to the CORIN promoter and enhances the promoter activity. Disruption of the KLF17 gene in the endometrial cells abolishes CORIN expression. In mice, Klf17 is up-regulated in the pregnant uterus. Klf17 deficiency prevents uterine Corin expression in pregnancy. Moreover, Klf17-deficient mice have poorly remodeled uterine spiral arteries and develop gestational hypertension and proteinuria. Together, our results reveal an important function of KLF17 in regulating Corin expression and uterine physiology in pregnancy.

Synthesis, Identification, and Structure-Activity Relationship Analysis of GATA4 and NKX2-5 Protein-Protein Interaction Modulators

Transcription factors GATA4 and NKX2-5 directly interact and synergistically activate several cardiac genes and stretch-induced cardiomyocyte hypertrophy. Previously, we identified phenylisoxazole carboxamide 1 as a hit compound, which inhibited the GATA4–NKX2-5 transcriptional synergy. Here, the chemical space around the molecular structure of 1 was explored by synthesizing and characterizing 220 derivatives and structurally related compounds. In addition to the synergistic transcriptional activation, selected compounds were evaluated for their effects on transcriptional activities of GATA4 and NKX2-5 individually as well as potential cytotoxicity. The structure–activity relationship (SAR) analysis revealed that the aromatic isoxazole substituent in the southern part regulates the inhibition of GATA4–NKX2-5 transcriptional synergy. Moreover, inhibition of GATA4 transcriptional activity correlated with the reduced cell viability. In summary, comprehensive SAR analysis accompanied by data analysis successfully identified potent and selective inhibitors of GATA4–NKX2-5 transcriptional synergy and revealed structural features important for it.

Galangin ameliorates cardiac remodeling via the MEK1/2-ERK1/2 and PI3K-AKT pathways

Cardiac remodeling is associated with inflammation and apoptosis. Galangin, as a natural flavonol, has the potent function of regulating inflammation and apoptosis, which are factors related to cardiac remodeling. Beginning 3 days after aortic banding (AB) or Sham surgery, mice were treated with galangin for 4 weeks. Cardiac remodeling was assessed according to echocardiographic parameters, histological analyses, and hypertrophy and fibrosis markers. Our results showed that galangin administration attenuated cardiac hypertrophy, dysfunction, and fibrosis response in AB mice and angiotensin II-treated H9c2 cells. The inhibitory action of galangin in cardiac remodeling was mediated by MEK1/2-extracellular-regulated protein kinases 1/2 (ERK1/2)-GATA4 and phosphoinositide 3-kinase (PI3K)-protein kinase B (AKT)-glycogen synthase kinase 3β (GSK3β) activation. Furthermore, we found that galangin inhibited inflammatory response and apoptosis. Our findings suggest that galangin protects against cardiac remodeling through decreasing inflammatory responses and apoptosis, which are associated with inhibition of the MEK1/2-ERK1/2-GATA4 and PI3K-AKT-GSK3β signals.

Targeting GATA4 for cardiac repair

Various strategies have been applied to replace the loss of cardiomyocytes in order to restore reduced cardiac function and prevent the progression of heart disease. Intensive research efforts in the field of cellular reprogramming and cell transplantation may eventually lead to efficient in vivo applications for the treatment of cardiac injuries, representing a novel treatment strategy for regenerative medicine. Modulation of cardiac transcription factor (TF) networks by chemical entities represents another viable option for therapeutic interventions. Comprehensive screening projects have revealed a number of molecular entities acting on molecular pathways highly critical for cellular lineage commitment and differentiation, including compounds targeting Wnt- and transforming growth factor beta (TGFβ)-signaling. Furthermore, previous studies have demonstrated that GATA4 and NKX2-5 are essential TFs in gene regulation of cardiac development and hypertrophy. For example, both of these TFs are required to fully activate mechanical stretch-responsive genes such as atrial natriuretic peptide and brain natriuretic peptide (BNP). We have previously reported that the compound 3i-1000 efficiently inhibited the synergy of the GATA4-NKX2-5 interaction. Cellular effects of 3i-1000 have been further characterized in a number of confirmatory in vitro bioassays, including rat cardiac myocytes and animal models of ischemic injury and angiotensin II-induced pressure overload, suggesting the potential for small molecule-induced cardioprotection.

Embryonic Cul4b is important for epiblast growth and location of primitive streak layer cells

Cul4b-null (Cul4bΔ/Y) mice undergo growth arrest and degeneration during the early embryonic stages and die at E9.5. The pathogenic causes of this lethality remain incompletely characterized. However, it has been hypothesized that the loss of Cul4b function in extraembryonic tissues plays a key role. In this study, we investigated possible causes of death for Cul4b-null embryos, particularly in regard to the role of embryonic Cul4b. First, we show that the loss of embryonic Cul4b affects the growth of the inner cell mass in vitro and delays epiblast development during the gastrulation period at E6.5~E7.5 in vivo, as highlighted by the absence of the epiblastic transcription factor Brachyury from E6.5~E7.5. Additionally, at E7.5, strong and laterally expanded expression of Eomes and Fgf8 signaling was detected. Sectioning of these embryos showed disorganized primitive streak layer cells. Second, we observed that Mash2-expressing cells were present in the extraembryonic tissues of Cul4b-deficient embryos at E6.5 but were absent at E7.5. In addition, the loss of Cul4b resulted in decreased expression of cyclin proteins, which are required for the cell cycle transition from G1 to S. Taken together, these observations suggest that the embryonic expression of Cul4b is important for epiblast growth during E6.5~E7.5, and the loss of Cul4b results in either delayed growth of the epiblast or defective localization of primitive streak layer cells. As a result, the signaling activity mediated by the epiblast for subsequent ectoplacental cone development is affected, with the potential to induce growth retardation and lethality in Cul4bΔ/Y embryos.

Retinoic Acid Induces Differentiation of Mouse F9 Embryonic Carcinoma Cell by Modulating the miR-485 Targeting of Abhd2

Retinoic acid (RA) plays a key role in pluripotent cell differentiation. In F9 embryonic carcinoma cells, RA can induce differentiation towards somatic lineages via the Ras-extracellular signal-regulated kinase (Ras/Erk) pathway, but the mechanism through which it induces the Erk1/2 phosphorylation is unclear. Here, we show that miR-485 is a positive regulator that targets α/β-hydrolase domain-containing protein 2 (Abhd2), which can result in Erk1/2 phosphorylation and triggers differentiation. RA up-regulates miR-485 and concurrently down-regulates Abhd2. We verified that Abhd2 is targeted by miR-485 and they both can influence the phosphorylation of Erk1/2. In summary, RA can mediate cell differentiation by phosphorylating Erk1/2 via miR-485 and Abhd2.

Transcription-dependent spreading of the Dal80 yeast GATA factor across the body of highly expressed genes

GATA transcription factors are highly conserved among eukaryotes and play roles in transcription of genes implicated in cancer progression and hematopoiesis. However, although their consensus binding sites have been well defined in vitro, the in vivo selectivity for recognition by GATA factors remains poorly characterized. Using ChIP-Seq, we identified the Dal80 GATA factor targets in yeast. Our data reveal Dal80 binding to a large set of promoters, sometimes independently of GATA sites, correlating with nitrogen- and/or Dal80-sensitive gene expression. Strikingly, Dal80 was also detected across the body of promoter-bound genes, correlating with high expression. Mechanistic single-gene experiments showed that Dal80 spreading across gene bodies requires active transcription. Consistently, Dal80 co-immunoprecipitated with the initiating and post-initiation forms of RNA Polymerase II. Our work suggests that GATA factors could play dual, synergistic roles during transcription initiation and post-initiation steps, promoting efficient remodeling of the gene expression program in response to environmental changes.

GATA transcription factors are highly conserved among eukaryotes and play key roles in cancer progression and hematopoiesis. In budding yeast, four GATA transcription factors are involved in the response to the quality of nitrogen supply. Here, we have determined the whole genome binding profile of the Dal80 GATA factor, and revealed that it also associates with the body of promoter-bound genes. The observation that intragenic spreading correlates with high expression levels and exquisite Dal80 sensitivity suggests that GATA factors could play other, unexpected roles at post-initiation stages in eukaryotes.

A Gata4 nuclear GFP transcriptional reporter to study endoderm and cardiac development in the mouse

The GATA zinc-finger transcription factor GATA4 is expressed in a variety of tissues during mouse embryonic development and in adult organs. These include the primitive endoderm of the blastocyst, visceral endoderm of the early post-implantation embryo, as well as lateral plate mesoderm, developing heart, liver, lung and gonads. Here, we generate a novel Gata4 targeted allele used to generate both a Gata4^H2B-GFP transcriptional reporter and a Gata4^FLAG fusion protein to analyse dynamic expression domains. We demonstrate that the Gata4^H2B-GFP transcriptional reporter faithfully recapitulates known sites of Gata4 mRNA expression and correlates with endogenous GATA4 protein levels. This reporter labels nuclei of Gata4 expressing cells and is suitable for time-lapse imaging and single cell analyses. As such, this Gata4^H2B-GFP allele will be a useful tool for studying Gata4 expression and transcriptional regulation.This article has an associated First Person interview with the first author of the paper.

STAT3-Inducible Mouse ESCs: A Model to Study the Role of STAT3 in ESC Maintenance and Lineage Differentiation

Studies have demonstrated that STAT3 is essential in maintaining self-renewal of embryonic stem cells (ESCs) and modulates ESC differentiation. However, there is still lack of direct evidence on STAT3 functions in ESCs and embryogenesis because constitutive STAT3 knockout (KO) mouse is embryonic lethal at E6.5-E7.5, prior to potential functional role in early development can be assessed. Therefore, in this study, two inducible STAT3 ESC lines were established, including the STAT3 knockout (InSTAT3 KO) and pSTAT3 overexpressed (InSTAT3 CA) using Tet-on inducible system in which STAT3 expression can be strictly controlled by doxycycline (Dox) stimulation. Through genotyping, deletion of STAT3 alleles was detected in InSTAT3 KO ESCs following 24 hours Dox stimulation. Western blot also showed that pSTAT3 and STAT3 protein levels were significantly reduced in InSTAT3 KO ESCs while dominantly elevated in InSTAT3 CA ECSs upon Dox stimulation. Likewise, it was found that STAT3-null ESCs would affect the differentiation of ESCs into mesoderm and cardiac lineage. Taken together, the findings of this study indicated that InSTAT3 KO and InSTAT3 CA ESCs could provide a new tool to clarify the direct targets of STAT3 and its role in ESC maintenance, which will facilitate the elaboration of the mechanisms whereby STAT3 maintains ESC pluripotency and regulates ESC differentiation during mammalian embryogenesis.

RERE deficiency leads to decreased expression of GATA4 and the development of ventricular septal defects

Deletions of chromosome 1p36 are associated with a high incidence of congenital heart defects (CHDs). The arginine-glutamic acid dipeptide repeats gene (RERE) is located in a critical region for CHD on chromosome 1p36 and encodes a cardiac-expressed nuclear receptor co-regulator. Mutations affecting RERE cause atrial and ventricular septal defects (VSDs) in humans, and RERE-deficient mice also develop VSDs. During cardiac development, mesenchymal cells destined to form part of the atrioventricular (AV) septum are generated when endocardial cells in the AV canal undergo epithelial-to-mesenchymal transition (EMT) and migrate into the space between the endocardium and the myocardium. These newly generated mesenchymal cells then proliferate to fill the developing AV endocardial cushions. Here, we demonstrate that RERE-deficient mouse embryos have reduced numbers of mesenchymal cells in their AV endocardial cushions owing to decreased levels of EMT and mesenchymal cell proliferation. In the endocardium, RERE colocalizes with GATA4, a transcription factor required for normal levels of EMT and mesenchymal cell proliferation. Using a combination of in vivo and in vitro studies, we show that Rere and Gata4 interact genetically in the development of CHDs, RERE positively regulates transcription from the Gata4 promoter and GATA4 levels are reduced in the AV canals of RERE-deficient embryos. Tissue-specific ablation of Rere in the endocardium leads to hypocellularity of the AV endocardial cushions, defective EMT and VSDs, but does not result in decreased GATA4 expression. We conclude that RERE functions in the AV canal to positively regulate the expression of GATA4, and that deficiency of RERE leads to the development of VSDs through its effects on EMT and mesenchymal cell proliferation. However, the cell-autonomous role of RERE in promoting EMT in the endocardium must be mediated by its effects on the expression of proteins other than GATA4.

This article has an associated First Person interview with the first author of the paper.

Summary: In the developing atrioventricular canal, RERE promotes endothelial-to-mesenchymal transition and mesenchymal cell proliferation by positively regulating Gata4. Tissue-specific ablation of Rere in the endocardium causes ventricular septal defects.

Stem cells are the most sensitive screening tool to identify toxicity of GATA4-targeted novel small-molecule compounds

Safety assessment of drug candidates in numerous in vitro and experimental animal models is expensive, time consuming and animal intensive. More thorough toxicity profiling already in the early drug discovery projects using human cell models, which more closely resemble the physiological cell types, would help to decrease drug development costs. In this study we aimed to compare different cardiac and stem cell models for in vitro toxicity testing and to elucidate structure–toxicity relationships of novel compounds targeting the cardiac transcription factor GATA4. By screening the effects of eight compounds at concentrations ranging from 10 nM up to 30 µM on the viability of eight different cell types, we identified significant cell type- and structure-dependent toxicity profiles. We further characterized two compounds in more detail using high-content analysis. The results highlight the importance of cell type selection for toxicity screening and indicate that stem cells represent the most sensitive screening model, which can detect toxicity that may otherwise remain unnoticed. Furthermore, our structure–toxicity analysis reveals a characteristic dihedral angle in the GATA4-targeted compounds that causes stem cell toxicity and thus helps to direct further drug development efforts towards non-toxic derivatives.

Inherited Cardiomyopathies and the Role of Mutations in Non-coding Regions of the Genome

Cardiomyopathies (CMs) are a group of cardiac pathologies caused by an intrinsic defect within the myocardium. The relative contribution of genetic mutations in the pathogenesis of certain CMs, such as hypertrophic cardiomyopathy (HCM), arrythmogenic right/left ventricular cardiomyopathy (ARVC) and left ventricular non-compacted cardiomyopathy (LVNC) has been established in comparison to dilated cardiomyopathy (DCM) and restrictive cardiomyopathy (RCM). The aim of this article is to review mutations in the non-coding parts of the genome, namely, microRNA, promoter elements, enhancer/silencer elements, 3′/5′UTRs and introns, that are involved in the pathogenesis CMs. Additionally, we will explore the role of some long non-coding RNAs in the pathogenesis of CMs.

GATA6 suppression enhances lung specification from human pluripotent stem cells

The transcription factor GATA6 has been shown to be important for lung development and branching morphogenesis in mouse models, but its role in human lung development is largely unknown. Here, we studied the role of GATA6 during lung differentiation using human pluripotent stem cells. We found that the human stem cell lines most efficient at generating NKX2.1+ lung progenitors express lower endogenous levels of GATA6 during endoderm patterning and that knockdown of GATA6 during endoderm patterning increased the generation of these cells. Complete ablation of GATA6 resulted in the generation of lung progenitors displaying increased cell proliferation with up to a 15-fold expansion compared with control cells, whereas the null cell line displayed a defect in further development into mature lung cell types. Furthermore, transgenic expression of GATA6 at the endoderm anteriorization stage skewed development toward a liver fate at the expense of lung progenitors. Our results suggest a critical dosage effect of GATA6 during human endoderm patterning and a later requirement during terminal lung differentiation. These studies offer an approach of modulating GATA6 expression to enhance the production of lung progenitors from human stem cell sources.

Parallel Genome-wide Profiling of Coding and Non-coding RNAs to Identify Novel Regulatory Elements in Embryonic and Maturated Heart

Heart development is a complex process, tightly regulated by numerous molecular mechanisms. Key components of the regulatory network underlying heart development are transcription factors (TFs) and microRNAs (miRNAs), yet limited investigation of the role of miRNAs in heart development has taken place. Here, we report the first parallel genome-wide profiling of polyadenylated RNAs and miRNAs in a developing murine heart. These data enable us to identify dynamic activation or repression of numerous biological processes and signaling pathways. More than 200 miRNAs and 25 long non-coding RNAs were differentially expressed during embryonic heart development compared to the mature heart; most of these had not been previously associated with cardiogenesis. Integrative analysis of expression data and potential regulatory interactions suggested 28 miRNAs as novel regulators of embryonic heart development, representing a considerable expansion of the current repertoire of known cardiac miRNAs. To facilitate follow-up investigations, we constructed HeartMiR (http://heartmir.sysbiolab.eu), an open access database and interactive visualization tool for the study of gene regulation by miRNAs during heart development.

Cardiac Actions of a Small Molecule Inhibitor Targeting GATA4-NKX2-5 Interaction

Transcription factors are fundamental regulators of gene transcription, and many diseases, such as heart diseases, are associated with deregulation of transcriptional networks. In the adult heart, zinc-finger transcription factor GATA4 is a critical regulator of cardiac repair and remodelling. Previous studies also suggest that NKX2-5 plays function role as a cofactor of GATA4. We have recently reported the identification of small molecules that either inhibit or enhance the GATA4–NKX2-5 transcriptional synergy. Here, we examined the cardiac actions of a potent inhibitor (3i-1000) of GATA4–NKX2-5 interaction in experimental models of myocardial ischemic injury and pressure overload. In mice after myocardial infarction, 3i-1000 significantly improved left ventricular ejection fraction and fractional shortening, and attenuated myocardial structural changes. The compound also improved cardiac function in an experimental model of angiotensin II -mediated hypertension in rats. Furthermore, the up-regulation of cardiac gene expression induced by myocardial infarction and ischemia reduced with treatment of 3i-1000 or when micro- and nanoparticles loaded with 3i-1000 were injected intramyocardially or intravenously, respectively. The compound inhibited stretch- and phenylephrine-induced hypertrophic response in neonatal rat cardiomyocytes. These results indicate significant potential for small molecules targeting GATA4–NKX2-5 interaction to promote myocardial repair after myocardial infarction and other cardiac injuries.

Early development of pleuroperitoneal fold of the diaphragm in the rat fetus

The embryonic diaphragm comprises four major structural components derived from the transverse septum, the dorsal foregut mesentery, the pleuroperitoneal folds (PPFs), and the body wall. In this study, the appearance of PPFs and related factors were investigated using light microscopy of horizontal sections of rat fetuses from embryonic day 12 to 13. In rat fetuses, the sign of PPF projection was noted in the sidewall of the pericardioperitoneal canal at embryonic day 12, and was confirmed as folds at embryonic day 12.25. Expressions of GATA4, COUP-TF2, and FOG2 were detected in PPF at the early stage of formation. Localizations of these factors suggested that COUP-TF2 and FOG2 are the main factors in PPF appearance and that GATA4 is unlikely to be a main factor, although it is necessary for PPF formation.

Regulation of Alpha-Secretase ADAM10 In vitro and In vivo: Genetic, Epigenetic, and Protein-Based Mechanisms

ADAM10 (A Disintegrin and Metalloproteinase 10) has been identified as the major physiological alpha-secretase in neurons, responsible for cleaving APP in a non-amyloidogenic manner. This cleavage results in the production of a neuroprotective APP-derived fragment, APPs-alpha, and an attenuated production of neurotoxic A-beta peptides. An increase in ADAM10 activity shifts the balance of APP processing toward APPs-alpha and protects the brain from amyloid deposition and disease. Thus, increasing ADAM10 activity has been proposed an attractive target for the treatment of neurodegenerative diseases and it appears to be timely to investigate the physiological mechanisms regulating ADAM10 expression. Therefore, in this article, we will (1) review reports on the physiological regulation of ADAM10 at the transcriptional level, by epigenetic factors, miRNAs and/or protein interactions, (2) describe conditions, which change ADAM10 expression in vitro and in vivo, (3) report how neuronal ADAM10 expression may be regulated in humans, and (4) discuss how this knowledge on the physiological and pathophysiological regulation of ADAM10 may help to preserve or restore brain function.

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

The GATA factor revolution in hematology

The discovery of the GATA binding protein (GATA factor) transcription factor family revolutionized hematology. Studies of GATA proteins have yielded vital contributions to our understanding of how hematopoietic stem and progenitor cells develop from precursors, how progenitors generate red blood cells, how hemoglobin synthesis is regulated, and the molecular underpinnings of nonmalignant and malignant hematologic disorders. This thrilling journey began with mechanistic studies on a β-globin enhancer- and promoter-binding factor, GATA-1, the founding member of the GATA family. This work ushered in the cloning of related proteins, GATA-2-6, with distinct and/or overlapping expression patterns. Herein, we discuss how the hematopoietic GATA factors (GATA-1-3) function via a battery of mechanistic permutations, which can be GATA factor subtype, cell type, and locus specific. Understanding this intriguing protein family requires consideration of how the mechanistic permutations are amalgamated into circuits to orchestrate processes of interest to the hematologist and more broadly.

Morphogenesis and maturation of the embryonic and postnatal intestine

The intestine is a vital organ responsible for nutrient absorption, bile and waste excretion, and a major site of host immunity. In order to keep up with daily demands, the intestine has evolved a mechanism to expand the absorptive surface area by undergoing a morphogenetic process to generate finger-like units called villi. These villi house specialized cell types critical for both absorbing nutrients from food, and for protecting the host from commensal and pathogenic microbes present in the adult gut. In this review, we will discuss mechanisms that coordinate intestinal development, growth, and maturation of the small intestine, starting from the formation of the early gut tube, through villus morphogenesis and into early postnatal life when the intestine must adapt to the acquisition of nutrients through food intake, and to interactions with microbes.

The ER stress regulator Bip mediates cadmium-induced autophagy and neuronal senescence

Autophagy is protective in cadmium (Cd)-induced oxidative damage. Endoplasmic reticulum (ER) stress has been shown to induce autophagy in a process requiring the unfolded protein response signalling pathways. Cd treatment significantly increased senescence in neuronal cells, which was aggravated by 3-MA or silencing of Atg5 and abolished by rapamycin. Cd increased expression of ER stress regulators Bip, chop, eIf2α, and ATF4, and activated autophagy as evidenced by upregulated LC3. Moreover, the ER stress inhibitor mithramycin inhibited the expression of ER stress protein chaperone Bip and blocked autophagic flux. Downregulating Bip significantly blocked the conversion of LC3-I to LC3-II, decreased LC3 puncta formation, and prevented the increase of senescence in PC12 cells. Interestingly, knocking down Bip regulated the expression of p-AMPK, p-AKT and p-s6k induced by Cd. BAPTA, a Bip inhibitor, decreased the expression of p-AMPK and LC3-II, but enhanced neuronal senescence. In addition, we found that siRNA for Bip enhanced GATA4 expression after 6 h Cd exposure in PC12 cells, while rapamycin treatment decreased GATA4 levels induced by 24 h Cd exposure. These results indicate that autophagy degraded GATA4 in a Bip-dependent way. Our findings suggest that autophagy regulated by Bip expression after ER stress suppressed Cd-induced neuronal senescence.

A Dynamic WNT/β-CATENIN Signaling Environment Leads to WNT-Independent and WNT-Dependent Proliferation of Embryonic Intestinal Progenitor Cells

Much of our understanding about how intestinal stem and progenitor cells are regulated comes from studying the late fetal stages of development and the adult intestine. In this light, little is known about intestine development prior to the formation of stereotypical villus structures with columnar epithelium, a stage when the epithelium is pseudostratified and appears to be a relatively uniform population of progenitor cells with high proliferative capacity. Here, we investigated a role for WNT/β-CATENIN signaling during the pseudostratified stages of development (E13.5, E14.5) and following villus formation (E15.5) in mice. In contrast to the well-described role for WNT/β-CATENIN signaling as a regulator of stem/progenitor cells in the late fetal and adult gut, conditional epithelial deletion of β-catenin or the Frizzled co-receptors Lrp5 and Lrp6 had no effect on epithelial progenitor cell proliferation in the pseudostratified epithelium. Mutant embryos displayed obvious developmental defects, including loss of proliferation and disruptions in villus formation starting only at E15.5. Mechanistically, our data suggest that WNT signaling-mediated proliferation at the time of villus formation is driven by mesenchymal, but not epithelial, WNT ligand secretion.

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WNT/β-CATENIN signaling is not required for proliferation during pseudostratified growth

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Deleting epithelial β-catenin causes loss of proliferation during villus morphogenesis

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Loss of WNT/β-CATENIN signaling leads to perturbations in villus formation

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Mesenchymal, not epithelial, WNT ligands are required for epithelial proliferation

Constitutive Expression of GATA4 Dramatically Increases the Cardiogenic Potential of D3 Mouse Embryonic Stem Cells

The transcription factor GATA binding protein 4 (GATA4) is a vital regulator of cardiac programming that acts by inducing the expression of many different genes involved in cardiomyogenesis. Here we generated a D3 mouse embryonic stem cell line that constitutively expresses high levels of GATA4 and show that these cells have dramatically increased cardiogenic potential compared to an eGFP-expressing control cell line. Embryoid bodies (EB) derived from the D3-GATA4 line displayed increased levels of cardiac gene expression and showed more abundant cardiomyocyte differentiation than control eGFP EB. These cells and two additional lines expressing lower levels of GATA4 provide a platform to screen previously untested cardiac genes and gene combinations for their ability to further increase the efficiency of cardiomyocyte differentiation beyond that achieved by transgenic GATA4 alone. Non-integrative delivery of identified gene combinations will aid in the production of differentiated cells for the treatment of ischemic cardiomyopathy.

Enrichment of G2/M cell cycle phase in human pluripotent stem cells enhances HDR-mediated gene repair with customizable endonucleases

Efficient gene editing is essential to fully utilize human pluripotent stem cells (hPSCs) in regenerative medicine. Custom endonuclease-based gene targeting involves two mechanisms of DNA repair: homology directed repair (HDR) and non-homologous end joining (NHEJ). HDR is the preferred mechanism for common applications such knock-in, knock-out or precise mutagenesis, but remains inefficient in hPSCs. Here, we demonstrate that synchronizing synchronizing hPSCs in G2/M with ABT phase increases on-target gene editing, defined as correct targeting cassette integration, 3 to 6 fold. We observed improved efficiency using ZFNs, TALENs, two CRISPR/Cas9, and CRISPR/Cas9 nickase to target five genes in three hPSC lines: three human embryonic stem cell lines, neural progenitors and diabetic iPSCs. neural progenitors and diabetic iPSCs. Reversible synchronization has no effect on pluripotency or differentiation. The increase in on-target gene editing is locus-independent and specific to the cell cycle phase as G2/M phase enriched cells show a 6-fold increase in targeting efficiency compared to cells in G1 phase. Concurrently inhibiting NHEJ with SCR7 does not increase HDR or improve gene targeting efficiency further, indicating that HR is the major DNA repair mechanism after G2/M phase arrest. The approach outlined here makes gene editing in hPSCs a more viable tool for disease modeling, regenerative medicine and cell-based therapies.

Unique functions of Gata4 in mouse liver induction and heart development

Gata4 and Gata6 are closely related transcription factors that are essential for the development of a number of embryonic tissues. While they have nearly identical DNA-binding domains and similar patterns of expression, Gata4 and Gata6 null embryos have strikingly different embryonic lethal phenotypes. To determine whether the lack of redundancy is due to differences in protein function or Gata4 and Gata6 expression domains, we generated mice that contained the Gata6 cDNA in place of the Gata4 genomic locus. Gata4(Gata6/Gata6) embryos survived through embryonic day (E)12.5 and successfully underwent ventral folding morphogenesis, demonstrating that Gata6 is able to replace Gata4 function in extraembryonic tissues. Surprisingly, Gata6 is unable to replace Gata4 function in the septum transversum mesenchyme or the epicardium, leading to liver agenesis and lethal heart defects in Gata4(Gata6/Gata6) embryos. These studies suggest that Gata4 has evolved distinct functions in the development of these tissues that cannot be performed by Gata6, even when it is provided in the identical expression domain. Our work has important implications for the respective mechanisms of Gata function during development, as well as the functional evolution of these essential transcription factors.

Nuclear Receptor-Like Structure and Interaction of Congenital Heart Disease-Associated Factors GATA4 and NKX2-5

AIMS

Transcription factor GATA4 is a dosage sensitive regulator of heart development and alterations in its level or activity lead to congenital heart disease (CHD). GATA4 has also been implicated in cardiac regeneration and repair. GATA4 action involves combinatorial interaction with other cofactors such as NKX2-5, another critical cardiac regulator whose mutations also cause CHD. Despite its critical importance to the heart and its evolutionary conservation across species, the structural basis of the GATA4-NKX2-5 interaction remains incompletely understood.

METHODS AND RESULTS

A homology model was constructed and used to identify surface amino acids important for the interaction of GATA4 and NKX2-5. These residues were subjected to site-directed mutagenesis, and the mutant proteins were characterized for their ability to bind DNA and to physically and functionally interact with NKX2-5. The studies identify 5 highly conserved amino acids in the second zinc finger (N272, R283, Q274, K299) and its C-terminal extension (R319) that are critical for physical and functional interaction with the third alpha helix of NKX2-5 homeodomain. Integration of the experimental data with computational modeling suggests that the structural arrangement of the zinc finger-homeodomain resembles the architecture of the conserved DNA binding domain of nuclear receptors.

CONCLUSIONS

The results provide novel insight into the structural basis for protein-protein interactions between two important classes of transcription factors. The model proposed will help to elucidate the molecular basis for disease causing mutations in GATA4 and NKX2-5 and may be relevant to other members of the GATA and NK classes of transcription factors.

FOXA2 regulates a network of genes involved in critical functions of human intestinal epithelial cells

The forkhead box A (FOXA) family of pioneer transcription factors is critical for the development of many endoderm-derived tissues. Their importance in regulating biological processes in the lung and liver is extensively characterized, though much less is known about their role in intestine. Here we investigate the contribution of FOXA2 to coordinating intestinal epithelial cell function using postconfluent Caco2 cells, differentiated into an enterocyte-like model. FOXA2 binding sites genome-wide were determined by ChIP-seq and direct targets of the factor were validated by ChIP-qPCR and siRNA-mediated depletion of FOXA1/2 followed by RT-qPCR. Peaks of FOXA2 occupancy were frequent at loci contributing to gene ontology pathways of regulation of cell migration, cell motion, and plasma membrane function. Depletion of both FOXA1 and FOXA2 led to a significant reduction in the expression of multiple transmembrane proteins including ion channels and transporters, which form a network that is essential for maintaining normal ion and solute transport. One of the targets was the adenosine A2B receptor, and reduced receptor mRNA levels were associated with a functional decrease in intracellular cyclic AMP. We also observed that 30% of FOXA2 binding sites contained a GATA motif and that FOXA1/A2 depletion reduced GATA-4, but not GATA-6 protein levels. These data show that FOXA2 plays a pivotal role in regulating intestinal epithelial cell function. Moreover, that the FOXA and GATA families of transcription factors may work cooperatively to regulate gene expression genome-wide in the intestinal epithelium.

Afzelin attenuates asthma phenotypes by downregulation of GATA3 in a murine model of asthma

Asthma is a serious health problem causing significant mortality and morbidity globally. Persistent airway inflammation, airway hyperresponsiveness, increased immunoglobulin E (IgE) levels and mucus hypersecretion are key characteristics of the condition. Asthma is mediated via a dominant T-helper 2 (Th2) immune response, causing enhanced expression of Th2 cytokines. These cytokines are responsible for the various pathological changes associated with allergic asthma. To investigate the anti-asthmatic potential of afzelin, as well as the underlying mechanisms involved, its anti-asthmatic potential were investigated in a murine model of asthma. In the present study, BALB/c mice were systemically sensitized using ovalbumin (OVA) followed by aerosol allergen challenges. The effect of afzelin on airway hyperresponsiveness, eosinophilic infiltration, Th2 cytokine and OVA-specific IgE production in a mouse model of asthma were investigated. It was found that afzelin-treated groups suppressed eosinophil infiltration, allergic airway inflammation, airway hyperresponsiveness, OVA-specific IgE and Th2 cytokine secretion. The results of the present study suggested that the therapeutic mechanism by which afzelin effectively treats asthma is based on reduction of Th2 cytokine via inhibition of GATA-binding protein 3 transcription factor, which is the master regulator of Th2 cytokine differentiation and production.

Unilateral cryptorchidism induces morphological changes of testes and hyperplasia of Sertoli cells in a dog

Cryptorchidism is one of the most common genital defects in dogs. This study investigated the effects of abdominal cryptorchidism on morphology, cell proliferation, and Sertoli cell condition in a dog with spontaneous unilateral cryptorchidism. Elective orchidectomy was performed on the abdominal right testis and the scrotal left testis. Significant reductions in numbers of spermatogonia, spermatocytes, and spermatids were observed in hematoxylin and eosin stained sections of the cryptorchid testis. The size of the epididymal duct was smaller than that of the control testis. Based on Ki67 immunohistochemistry, the proliferative activity of spermatogonia and spermatocytes was significantly decreased in the cryptorchid testis. However, proliferative activity was increased in the epididymal duct. Based on GATA-4 immunohistochemistry, Sertoli cells were relatively resistant to cryptorchidism, and the proliferative activity of Sertoli cells was markedly increased in the cryptorchid testis than in the control testis. These results suggest that spontaneous unilateral cryptorchidism causes morphological defects in spermatogonia and spermatocytes in the testis and changes the size of the efferent ductule of the epididymis. In addition, spontaneous unilateral cryptorchidism increases proliferative activity of Sertoli cells, which may be a predisposing factor for Sertoli cell cancer in cryptorchid testes.

Exploring features and function of Ss-riok-3, an enigmatic kinase gene from Strongyloides stercoralis

Background

Right open reading frame protein kinase 3 (RIOK-3) belongs to the atypical kinase family. Unlike the other two members, RIOK-1 and RIOK-2, which are conserved from Archaea to humans, RIOK-3 occurs only in multicellular organisms. Studies on HeLa cells indicate that human RIOK-3 is a component of the 40S small ribosome subunit and supports cancer cell growth and survival. However, almost nothing is known about the function of RIOK-3. We explored the functional role of RIOK-3 encoding gene from Strongyloides stercoralis, a parasitic nematode of humans and dogs.

Methods

To analyze the gene and promoter structure of Ss-riok-3, RACE-PCR and Genome-walker PCR were performed to isolate the full length cDNA, gDNA and promoter region of Ss-riok-3. RNA-seq was conducted to assess the transcript abundance of Ss-riok-3 in different stages of S. stercoralis. Transgenesis was employed to determine the anatomic expression patterns of Ss-riok-3.

Results

The RIOK-3 protein-encoding gene (designated Ss-riok-3) of S. stercoralis was characterized. The full-length complementary and genomic DNAs of the RIOK-3 encoding gene (riok-3) were isolated from this nematode. The cDNA of Ss-riok-3 is 1,757 bp in length, including a 23 bp 5’-UTR, a 36 bp 3’-UTR and a 1,698 bp coding region encoding a protein of 565 amino acids (aa) containing a RIO kinase domain. RNA sequencing (RNA-seq) analysis revealed that Ss-riok-3 is transcribed in all developmental stages of S. stercoralis assessed, with transcripts being particularly abundant in parasitic females. Gene structure analysis revealed that Ss-riok-3 contains no intron. The putative promoter contains conserved promoter elements, including four TATA, two GATA, one inverse GATA and one inverse CAAT boxes. The promoter of Ss-riok-3 drives GFP expression in the head neuron, intestine and body wall muscle of transgenic S. stercoralis larvae, and the TATA boxes present in the 3’-UTR of the gene immediately upstream of Ss-riok-3 initiate transcription.

Conclusions

The characterization of the RIOK-3 encoding gene from S. stercoralis provides a sound foundation for investigating in detail its function in the development and reproduction of this important pathogen.

Electronic supplementary material

The online version of this article (doi:10.1186/s13071-014-0561-z) contains supplementary material, which is available to authorized users.

Impact of GATA4 variants on stable warfarin doses in patients with prosthetic heart valves

Interindividual variability in stable warfarin doses is largely attributed to VKORC1 and CYP2C9 variants. On the basis of a recent finding of the role of GATA4 in control of CYP2C9 expression, we tested a possible effect of GATA4 genotypes on variability in warfarin response using 201 Korean patients with prosthetic cardiac valves. Two single-nucleotide polymorphisms (SNPs), rs2645400 (G>T) and rs4841588 (G>T), were significantly associated with stable warfarin doses in patients carrying CYP2C9 wild-type homozygotes; homozygote carriers of these two SNPs required higher doses than those with other genotypes (5.94±1.73 versus 5.34±1.88 mg, P=0.026; 5.94±1.66 versus 5.37±1.92, P=0.036, respectively). Multivariate analysis showed that two GATA4 combinations, rs867858 (G>T)/rs10090884 (A>C) and rs2645400 (G>T)/rs4841588 (G>T), increased contribution to the overall warfarin dose variability from 36.4 to 40.9%. This study revealed that GATA4 can be predictive of stable warfarin dose and extended warfarin pharmacogenetics further to the regulation of CYP2C9 expression.

GATA4 immunolocalization in breast carcinoma as a potent prognostic predictor

Transcriptional GATA factors are known lineage selector genes and regulate a variety of biological processes including specification and differentiation of tissues. In the present study, we examined expression profiles of six GATA factor genes in invasive ductal carcinomas (IDC) of the breast using microarray analysis (n = 20) and found that GATA4 expression was closely correlated with recurrence in patients. Because the significance of GATA4 has remained largely unknown in breast carcinoma, we further immunolocalized GATA4 in ductal carcinoma in situ (DCIS) of the breast (n = 48) and IDC (n = 163). GATA4 immunoreactivity was detected in the nuclei of carcinoma cells and was positive in 27% of DCIS and 31% of IDC cases. GATA4 status was significantly associated with nuclear grade and van Nuys classification in DCIS and was positively associated with distant metastasis, histological grade and HER2 status, but negatively correlated with progesterone receptor labeling index in IDC. Subsequent multivariate analysis demonstrated that GATA4 status was an independent prognostic factor for both disease-free and breast cancer-specific survival of IDC patients. All of these results indicate that GATA4 plays important roles in the progression of breast carcinoma from an early stage and that immunohistochemical GATA4 status is considered a potent prognostic factor in human breast cancer patients.

Multiple nuclear localization signals mediate nuclear localization of the GATA transcription factor AreA

The Aspergillus nidulans GATA transcription factor AreA activates transcription of nitrogen metabolic genes in response to nitrogen limitation and is known to accumulate in the nucleus during nitrogen starvation. Sequence analysis of AreA revealed multiple nuclear localization signals (NLSs), five putative classical NLSs conserved in fungal AreA orthologs but not in the Saccharomyces cerevisiae functional orthologs Gln3p and Gat1p, and one putative noncanonical RRX33RXR bipartite NLS within the DNA-binding domain. In order to identify the functional NLSs in AreA, we constructed areA mutants with mutations in individual putative NLSs or combinations of putative NLSs and strains expressing green fluorescent protein (GFP)-AreA NLS fusion genes. Deletion of all five classical NLSs individually or collectively did not affect utilization of nitrogen sources or AreA-dependent gene expression and did not prevent AreA nuclear localization. Mutation of the bipartite NLS conferred the inability to utilize alternative nitrogen sources and abolished AreA-dependent gene expression likely due to effects on DNA binding but did not prevent AreA nuclear localization. Mutation of all six NLSs simultaneously prevented AreA nuclear accumulation. The bipartite NLS alone strongly directed GFP to the nucleus, whereas the classical NLSs collaborated to direct GFP to the nucleus. Therefore, AreA contains multiple conserved NLSs, which show redundancy and together function to mediate nuclear import. The noncanonical bipartite NLS is conserved in GATA factors from Aspergillus, yeast, and mammals, indicating an ancient origin.

Linking GATA-3 and interleukin-13: implications in asthma

INTRODUCTION

Asthma is one of the serious global health problems and cause of huge mortality and morbidity. It is characterized by persistent airway inflammation, airway hyperresponsiveness, increased IgE levels and mucus hypersecretion. Asthma is mediated by dominant Th2 immune response, causing enhanced expression of Th2 cytokines. These cytokines are responsible for the various pathological changes associated with allergic asthma.

MATERIALS AND METHODS

The role of Th2 cells in the pathogenesis of the asthma is primarily mediated through the cytokine IL-13, also produced by type 2 innate lymphoid cells, that comes under the transcriptional regulation of GATA3. In this review we will try to explore the link between IL-13 and GATA3 in the progression and regulation of asthma and its possible role as a therapeutic target.

CONCLUSION

Inhibition of GATA3 activity or blockade of GATA3 expression may attenuate the interleukin-13 mediated asthma phenotypes. So, GATA3 might be a potential therapeutic target for the treatment of allergic asthma.

Embryonic heart progenitors and cardiogenesis

The mammalian heart is a highly specialized organ, comprised of many different cell types arising from distinct embryonic progenitor populations during cardiogenesis. Three precursor populations have been identified to contribute to different myocytic and nonmyocytic cell lineages of the heart: cardiogenic mesoderm cells (CMC), the proepicardium (PE), and cardiac neural crest cells (CNCCs). This review will focus on molecular cues necessary for proper induction, expansion, and lineage-specific differentiation of these progenitor populations during cardiac development in vivo. Moreover, we will briefly discuss how the knowledge gained on embryonic heart progenitor biology can be used to develop novel therapeutic strategies for the management of congenital heart disease as well as for improvement of cardiac function in ischemic heart disease.

Transcriptional mechanisms underlying hemoglobin synthesis

The physiological switch in expression of the embryonic, fetal, and adult β-like globin genes has garnered enormous attention from investigators interested in transcriptional mechanisms and the molecular basis of hemoglobinopathies. These efforts have led to the discovery of cell type-specific transcription factors, unprecedented mechanisms of transcriptional coregulator function, genome biology principles, unique contributions of nuclear organization to transcription and cell function, and promising therapeutic targets. Given the vast literature accrued on this topic, this article will focus on the master regulator of erythroid cell development and function GATA-1, its associated proteins, and its frontline role in controlling hemoglobin synthesis. GATA-1 is a crucial regulator of genes encoding hemoglobin subunits and heme biosynthetic enzymes. GATA-1-dependent mechanisms constitute an essential regulatory core that nucleates additional mechanisms to achieve the physiological control of hemoglobin synthesis.

NADPH oxidase 4 regulates cardiomyocyte differentiation via redox activation of c-Jun protein and the cis-regulation of GATA-4 gene transcription

NADPH oxidase 4 (Nox4) generates reactive oxygen species (ROS) that can modulate cellular phenotype and function in part through the redox modulation of the activity of transcription factors. We demonstrate here the potential of Nox4 to drive cardiomyocyte differentiation in pluripotent embryonal carcinoma cells, and we show that this involves the redox activation of c-Jun. This in turn acts to up-regulate GATA-4 expression, one of the earliest markers of cardiotypic differentiation, through a defined and highly conserved cis-acting motif within the GATA-4 promoter. These data therefore suggest a mechanism whereby ROS act in pluripotential cells in vivo to regulate the initial transcription of critical tissue-restricted determinant(s) of the cardiomyocyte phenotype, including GATA-4. The ROS-dependent activation, mediated by Nox4, of widely expressed redox-regulated transcription factors, such as c-Jun, is fundamental to this process.

Comparative Analysis of Nkx2-5/GATA4/TBX5 Expression in Chicken, Quail and Chicken-quail Hybrids during the Early Stage of Cardiac Development in Embryos

The present study makes an investigation into expression of genes related to cardiac development in chicken, quail and chicken-quail hybrids during the early stage of embryogenesis. Real-time PCR was used to detect mRNA expressions of Nkx2-5, GATA4 and TBX5 in the heart of chicken, quail and chicken-quail hybrids embryos during the 3rd to 7th days of incubation. Results showed that NKX2-5 mRNA displayed a similar expression trend in chicken, quail and chicken-quail hybrids. The initial and highest expression of Nkx2-5 was focused on the 3rd day of incubation, then it declined till 5th day of incubation, thereafter, it fluctuated. Expression of Nkx2-5 gene in quail was significantly higher than in chicken and chicken-quail hybrids, and no significant difference was observed between the two latter species. GATA4 mRNA showed a similar expression trend between chicken and quail, which displayed a steady increase from 3rd to 6th d, then, the expression level decreased. However, GATA4 mRNA expression in chicken-quail hybrids was significantly higher than that in chicken and quail from 3rd to 5th d (p<0.01), but significantly lower than that in chicken and quail during the later stage of the experiment (p<0.05), due to the dramatic drop from 5th d onwards (p<0.01). TBX5 mRNA expression in chicken and quail showed the same trend as GATA4 expressed in the two species. Furthermore, TBX5 expression in chicken-quail hybrids was significantly higher than that in chicken and quail during the whole course of experiment, although relatively lower TBX5 expression was detected in the early stage. In conclusion, Nkx2-5, GATA4 and TBX5 genes showed dynamic changes during the process of cardiac development in chicken, quail and their hybrids embryos. In addition, the expression trend in chicken was similar to that in quail, and there was no significant difference for gene expression level, except NKX2-5. However, expression of these genes in chicken-quail hybrids was significantly different from their parents, the difference mechanism needs to be further explored.

Variants in GATA4 are a rare cause of familial and sporadic congenital diaphragmatic hernia

Congenital diaphragmatic hernia (CDH) is characterized by incomplete formation of the diaphragm occurring as either an isolated defect or in association with other anomalies. Genetic factors including aneuploidies and copy number variants are important in the pathogenesis of many cases of CDH, but few single genes have been definitively implicated in human CDH. In this study, we used whole exome sequencing (WES) to identify a paternally inherited novel missense GATA4 variant (c.754C>T; p.R252W) in a familial case of CDH with incomplete penetrance. Phenotypic characterization of the family included magnetic resonance imaging of the chest and abdomen demonstrating asymptomatic defects in the diaphragm in the two "unaffected" missense variant carriers. Screening 96 additional CDH patients identified a de novo heterozygous GATA4 variant (c.848G>A; p.R283H) in a non-isolated CDH patient. In summary, GATA4 is implicated in both familial and sporadic CDH, and our data suggests that WES may be a powerful tool to discover rare variants for CDH.

Anatomy of a blastocyst: cell behaviors driving cell fate choice and morphogenesis in the early mouse embryo

The preimplantation period of mouse early embryonic development is devoted to the specification of two extraembryonic tissues and their spatial segregation from the pluripotent epiblast. During this period two cell fate decisions are made while cells gradually lose their totipotency. The first fate decision involves the segregation of the extraembryonic trophectoderm (TE) lineage from the inner cell mass (ICM); the second occurs within the ICM and involves the segregation of the extraembryonic primitive endoderm (PrE) lineage from the pluripotent epiblast (EPI) lineage, which eventually gives rise to the embryo proper. Multiple determinants, such as differential cellular properties, signaling cues and the activity of transcriptional regulators, influence lineage choice in the early embryo. Here, we provide an overview of our current understanding of the mechanisms governing these cell fate decisions ensuring proper lineage allocation and segregation, while at the same time providing the embryo with an inherent flexibility to adjust when perturbed.