Essential role of the zinc finger transcription factor Casz1 for mammalian cardiac morphogenesis and development

SCIG: Machine learning uncovers cell identity genes in single cells by genetic sequence codes

Deciphering cell identity genes is pivotal to understanding cell differentiation, development, and cell identity dysregulation involving diseases. Here, we introduce SCIG, a machine-learning method to uncover cell identity genes in single cells. In alignment with recent reports that cell identity genes (CIGs) are regulated with unique epigenetic signatures, we found CIGs exhibit distinctive genetic sequence signatures, e.g. unique enrichment patterns of cis-regulatory elements. Using these genetic sequence signatures, along with gene expression information from single-cell RNA-seq data, SCIG uncovers the identity genes of a cell without a need for comparison to other cells. CIG score defined by SCIG surpassed expression value in network analysis to reveal the master transcription factors (TFs) regulating cell identity. Applying SCIG to the human endothelial cell atlas revealed that the tissue microenvironment is a critical supplement to master TFs for cell identity refinement. SCIG is publicly available at https://doi.org/10.5281/zenodo.14726426  , offering a valuable tool for advancing cell differentiation, development, and regenerative medicine research.

Casz1 is required for both inner hair cell fate stabilization and outer hair cell survival

Cochlear inner hair cells (IHCs) and outer hair cells (OHCs) require different transcription factors for their cell fate stabilization and survival, which suggests that separate mechanisms are involved. In this study, we found that the transcription factor Casz1 is crucial for early IHC fate consolidation and for OHC survival during mouse development. Loss of Casz1 resulted in transdifferentiation of IHCs into OHCs, without affecting OHC production. However, long-term OHC survival was compromised in Casz1 mutant mice. In addition, the transcription factor Gata3 was down-regulated in Casz1-deleted IHCs, and overexpressing Gata3 partially rescued IHC properties, OHC numbers, and hearing in Casz1-deleted mice. Thus, Casz1 plays critical roles in early IHC fate stabilization and OHC survival and could potentially provide a lead for therapies aimed at regenerating both IHCs and OHCs.

SMYD1 modulates the proliferation of multipotent cardiac progenitor cells derived from human pluripotent stem cells during myocardial differentiation through GSK3β/β-catenin&ERK signaling

BACKGROUND

The histone-lysine N-methyltransferase SMYD1, which is specific to striated muscle, plays a crucial role in regulating early heart development. Its deficiency has been linked to the occurrence of congenital heart disease. Nevertheless, the precise mechanism by which SMYD1 deficiency contributes to congenital heart disease remains unclear.

METHODS

We established a SMYD1 knockout pluripotent stem cell line and a doxycycline-inducible SMYD1 expression pluripotent stem cell line to investigate the functions of SMYD1 utilizing an in vitro-directed myocardial differentiation model.

RESULTS

Cardiomyocytes lacking SMYD1 displayed drastically diminished differentiation efficiency, concomitant with heightened proliferation capacity of cardiac progenitor cells during the early cardiac differentiation stage. These cellular phenotypes were confirmed through experiments inducing the re-expression of SMYD1. Transcriptome sequencing and small molecule inhibitor intervention suggested that the GSK3β/β-catenin&ERK signaling pathway was involved in the proliferation of cardiac progenitor cells. Chromatin immunoprecipitation demonstrated that SMYD1 acted as a transcriptional activator of GSK3β through histone H3 lysine 4 trimethylation. Additionally, dual-luciferase analyses indicated that SMYD1 could interact with the promoter region of GSK3β, thereby augmenting its transcriptional activity. Moreover, administering insulin and Insulin-like growth factor 1 can enhance the efficacy of myocardial differentiation in SMYD1 knockout cells.

CONCLUSIONS

Our research indicated that the participation of SMYD1 in the GSK3β/β-catenin&ERK signaling cascade modulated the proliferation of cardiac progenitor cells during myocardial differentiation. This process was partly reliant on the transcription of GSK3β. Our research provided a novel insight into the genetic modification effect of SMYD1 during early myocardial differentiation. The findings were essential to the molecular mechanism and potential interventions for congenital heart disease.

CASZ1 Is Essential for Skin Epidermal Terminal Differentiation

The barrier function of skin epidermis is crucial for our bodies to interface with the environment. Because epidermis continuously turns over throughout the lifetime, this barrier must be actively maintained by regeneration. Although several transcription factors have been established as essential activators in epidermal differentiation, it is unclear whether additional factors remain to be identified. In this study, we show that CASZ1, a multi zinc-finger transcription factor previously characterized in nonepithelial cell types, shows highest expression in skin epidermis. CASZ1 expression is upregulated during epidermal terminal differentiation. In addition, CASZ1 expression is impaired in several skin disorders with impaired barrier function, such as atopic dermatitis, psoriasis, and squamous cell carcinoma. Using transcriptome profiling coupled with RNA interference, we identified 674 differentially expressed genes with CASZ1 knockdown. Downregulated genes account for 91.2% of these differentially expressed genes and were enriched for barrier function. In organotypic epidermal regeneration, CASZ1 knockdown promoted proliferation and strongly impaired multiple terminal differentiation markers. Mechanistically, we found that CASZ1 upregulation in differentiation requires the action of both the master transcription factor, p63, and the histone acetyltransferase, p300. Taken together, our findings identify CASZ1 as an essential activator of epidermal differentiation, paving the way for future studies understanding of CASZ1 roles in skin disease.

DNA damage-associated protein co-expression network in cardiomyocytes informs on tolerance to genetic variation and disease

Cardiovascular disease (CVD) is associated with both genetic variants and environmental factors. One unifying consequence of the molecular risk factors in CVD is DNA damage, which must be repaired by DNA damage response proteins. However, the impact of DNA damage on global cardiomyocyte protein abundance, and its relationship to CVD risk remains unclear. We therefore treated induced pluripotent stem cell-derived cardiomyocytes with the DNA-damaging agent Doxorubicin (DOX) and a vehicle control, and identified 4,178 proteins that contribute to a network comprising 12 co-expressed modules and 403 hub proteins with high intramodular connectivity. Five modules correlate with DOX and represent distinct biological processes including RNA processing, chromatin regulation and metabolism. DOX-correlated hub proteins are depleted for proteins that vary in expression across individuals due to genetic variation but are enriched for proteins encoded by loss-of-function intolerant genes. While proteins associated with genetic risk for CVD, such as arrhythmia are enriched in specific DOX-correlated modules, DOX-correlated hub proteins are not enriched for known CVD risk proteins. Instead, they are enriched among proteins that physically interact with CVD risk proteins. Our data demonstrate that DNA damage in cardiomyocytes induces diverse effects on biological processes through protein co-expression modules that are relevant for CVD, and that the level of protein connectivity in DNA damage-associated modules influences the tolerance to genetic variation.

CApSiZing T-cell acute lymphoblastic leukemia

Not available.

Role of the CASZ1 transcription factor in tissue development and disease

The zinc finger transcription factor gene, CASZ1/Castor (Castor zinc finger 1), initially identified in Drosophila, plays a critical role in neural, cardiac, and cardiovascular development, exerting a complex, multifaceted influence on cell fate and tissue morphogenesis. During neurogenesis, CASZ1 exhibits dynamic expression from early embryonic development to the perinatal period, constituting a key regulator in this process. Additionally, CASZ1 controls the transition between neurogenesis and gliomagenesis. During human cardiovascular system development, CASZ1 is essential for cardiomyocyte differentiation, cardiac morphogenesis, and vascular morphology homeostasis and formation. The deletion or inactivation of CASZ1 mutations can lead to human developmental diseases or tumors, including congenital heart disease, cardiovascular disease, and neuroblastoma. CASZ1 can be used as a biomarker for disease prevention and diagnosis as well as a prognostic indicator for cancer. This review explores the unique functions of CASZ1 in tissue morphogenesis and associated diseases, offering new insights for elucidating the molecular mechanisms underlying diseases and identifying potential therapeutic targets for disease prevention and treatment.

Association of CASZ1 genetic variants with stroke risk in the Chinese population

BACKGROUND

Stroke is a heterogeneous disease with multiple etiologies, placing a heavy burden on the world. Our purpose was to clarify the association between CASZ1 genetic variants and stroke risk in the Chinese population.

METHODS

The Agena MassARRAY platform effectively genotyped three single nucleotide polymorphisms of CASZ1 in recruited 591 stroke patients and 553 healthy controls. Logistic regression genetic models were employed to evaluate the relationship between CASZ1 polymorphisms and stroke risk through odds ratios (ORs) and 95% confidence intervals (CIs). Then, the interaction between CASZ1 variants was detected by multifactor dimensionality reduction (MDR). Moreover, functional enrichment analyses of the CASZ1 gene were performed by Metascape.

RESULTS

In this study, CASZ1 rs4845941 and rs778228 were significantly associated with an increased risk of stroke. In particular, the gender-stratified analysis also showed that rs778228 of CASZ1 had an association with higher stroke risk in females. The relationship between stroke susceptibility and the interaction models of rs4845941, rs778228, and rs17035539 forecasted by MDR were analyzed to improve the ability to predict stroke risk. Furthermore, we found CASZ1 and related genes might facilitate the occurrence of stroke.

CONCLUSIONS

This study demonstrated that CASZ1 genetic variants (rs4845941 and rs778228) contribute to the occurrence of stroke in the Chinese population, and therefore has important implications for treating and preventing stroke.

CASZ1: Current Implications in Cardiovascular Diseases and Cancers

Castor zinc finger 1 (CASZ1) is a C2H2 zinc finger family protein that has two splicing variants, CASZ1a and CASZ1b. It is involved in multiple physiological processes, such as tissue differentiation and aldosterone antagonism. Genetic and epigenetic alternations of CASZ1 have been characterized in multiple cardiovascular disorders, such as congenital heart diseases, chronic venous diseases, and hypertension. However, little is known about how CASZ1 mechanically participates in the pathogenesis of these diseases. Over the past decades, at first glance, paradoxical influences on cell behaviors and progressions of different cancer types have been discovered for CASZ1, which may be explained by a "double-agent" role for CASZ1. In this review, we discuss the physiological function of CASZ1, and focus on the association of CASZ1 aberrations with the pathogenesis of cardiovascular diseases and cancers.

Cooperative regulation of Zhx1 and hnRNPA1 drives the cardiac progenitor-specific transcriptional activation during cardiomyocyte differentiation

The zinc finger proteins (ZNFs) mediated transcriptional regulation is critical for cell fate transition. However, it is still unclear how the ZNFs realize their specific regulatory roles in the stage-specific determination of cardiomyocyte differentiation. Here, we reported that the zinc fingers and homeoboxes 1 (Zhx1) protein, transiently expressed during the cell fate transition from mesoderm to cardiac progenitors, was indispensable for the proper cardiomyocyte differentiation of mouse and human embryonic stem cells. Moreover, Zhx1 majorly promoted the specification of cardiac progenitors via interacting with hnRNPA1 and co-activated the transcription of a wide range of genes. In-depth mechanistic studies showed that Zhx1 was bound with hnRNPA1 by the amino acid residues (Thr111-His120) of the second Znf domain, thus participating in the formation of cardiac progenitors. Together, our study highlights the unrevealed interaction of Zhx1/hnRNPA1 for activating gene transcription during cardiac progenitor specification and also provides new evidence for the specificity of cell fate determination in cardiomyocyte differentiation.

Zinc finger transcription factor CASZ1b is involved in the DNA damage response in live cells

Zinc finger transcription factor CASZ1b is essential for nervous system development and suppresses neuroblastoma growth. Our previous study showed that CASZ1b interacts with DNA repair proteins, however, whether CASZ1b is involved in the DNA damage response remains unclear. In this study, we investigated the kinetic recruitment of CASZ1b to sites of DNA damage upon induction by laser microirradiation. We find that CASZ1b is transiently recruited to sites of DNA damage in multiple cell lines. Mutagenesis of either the poly-(ADP-ribose) (PAR) binding motif or NuRD complex binding region in CASZ1b significantly reduces the recruitment of CASZ1b to these sites of DNA damage (∼65% and ∼30%, respectively). In addition, treatment of cells with a poly-(ADP-ribose) polymerase (PARP) inhibitor significantly attenuates the recruitment of CASZ1b to these DNA damaged sites. Loss of CASZ1 increases cell sensitivity to DNA damage induced by gamma irradiation as shown by decreased colony formation. Our studies reveal that CASZ1b is transiently recruited to DNA damage sites mainly in a PARP-dependent way and regulates cell sensitivity to DNA damage. Our results suggest that CASZ1b has a role, although perhaps a minor one, in the DNA damage response and ultimately regulating the efficiency of DNA repair during normal development and tumorigenesis.

Endothelial deletion of PTBP1 disrupts ventricular chamber development

The growth and maturation of the ventricular chamber require spatiotemporally precise synergy between diverse cell types. Alternative splicing deeply affects the processes. However, the functional properties of alternative splicing in cardiac development are largely unknown. Our study reveals that an alternative splicing factor polypyrimidine tract-binding protein 1 (PTBP1) plays a key role in ventricular chamber morphogenesis. During heart development, PTBP1 colocalizes with endothelial cells but is almost undetectable in cardiomyocytes. The endothelial-specific knockout of Ptbp1, in either endocardial cells or pan-endothelial cells, leads to a typical phenotype of left ventricular noncompaction (LVNC). Mechanistically, the deletion of Ptbp1 reduces the migration of endothelial cells, disrupting cardiomyocyte proliferation and ultimately leading to the LVNC. Further study shows that Ptbp1 deficiency changes the alternative splicing of β-arrestin-1 (Arrb1), which affects endothelial cell migration. In conclusion, as an alternative splicing factor, PTBP1 is essential during ventricular chamber development, and its deficiency can lead to congenital heart disease.

CASZ1 promotes migration, invasion, and metastasis of lung cancer cells by controlling expression of ITGAV

CASZ1, a zinc finger transcription factor with two isoforms, is known to play important roles in cardiac and neural development. The abnormal expression of CASZ1 is also frequently found in a variety of tumors but has different effects on different tumors; for example, it acts as a tumor suppressor in neuroblastoma but promotes cancer metastasis in ovarian cancer. However, the effect of CASZ1 in lung cancer, the most lethal cancer, remains unclear. Here, we found that the expression of CASZ1 in lung cancer is positively associated with cancer metastasis and poor prognosis. The overexpression of CASZ1b promotes lung cancer cell migration, invasion, and epithelial-mesenchymal transition and is associated with poor prognosis in lung cancer patients. The knockdown of CASZ1 resulted in the suppression of epithelial-mesenchymal transition, migration, and invasion of lung cancer cells and reduced metastasis in vivo. The results of an RNA-sequencing analysis of CASZ1-silenced cells showed that CASZ1 considerably affected the integrin-mediated pathways. CASZ1 bound to the ITGAV promoter and transcriptionally regulated ITGAV expression. Our findings demonstrate that CASZ1 plays an oncogenic role in lung cancer and that CASZ1 promotes lung cancer migration, invasion and metastasis is mediated by ITGAV.

Actin cytoskeleton in angiogenesis

Actin, one of the most abundant intracellular proteins in mammalian cells, is a critical regulator of cell shape and polarity, migration, cell division, and transcriptional response. Angiogenesis, or the formation of new blood vessels in the body is a well-coordinated multi-step process. Endothelial cells lining the blood vessels acquire several new properties such as front-rear polarity, invasiveness, rapid proliferation and motility during angiogenesis. This is achieved by changes in the regulation of the actin cytoskeleton. Actin remodelling underlies the switch between the quiescent and angiogenic state of the endothelium. Actin forms endothelium-specific structures that support uniquely endothelial functions. Actin regulators at endothelial cell-cell junctions maintain the integrity of the blood-tissue barrier while permitting trans-endothelial leukocyte migration. This review focuses on endothelial actin structures and less-recognised actin-mediated endothelial functions. Readers are referred to other recent reviews for the well-recognised roles of actin in endothelial motility, barrier functions and leukocyte transmigration. Actin generates forces that are transmitted to the extracellular matrix resulting in vascular matrix remodelling. In this review, we attempt to synthesize our current understanding of the roles of actin in vascular morphogenesis. We speculate on the vascular bed specific differences in endothelial actin regulation and its role in the vast heterogeneity in endothelial morphology and function across the various tissues of our body.

Identification of a Novel de Novo Variant in the CASZ1 Causing a Rare Type of Dilated Cardiomyopathy

A new de novo frameshift variant has been identified in the CASZ1 gene leading to severe dilated cardiomyopathy. Methods: The proband was analyzed with WES NGS, post-mortem, using dried blood spots on filters. The variant was verified with Sanger sequencing for the proband and her parents. Results: We reported a proband with a new de novo frameshift mutation, c.3781del (p.(Trp1261GlyfsTer29)), in the CASZ1 gene. The clinical presentation was similar to the severe phenotype described in previous studies. Conclusions: In this study, we described a new case with a frameshift mutation in CASZ1 causing a severe phenotype of dilated cardiomyopathy.

Loss of CASZ1 tumor suppressor linked to oncogenic subversion of neuroblastoma core regulatory circuitry

The neural crest lineage regulatory transcription factors (TFs) form a core regulatory circuitry (CRC) in neuroblastoma (NB) to specify a noradrenergic tumor phenotype. Oncogenic subversion of CRC TFs is well documented, but the role of loss of tumor suppressors plays remains unclear. Zinc-finger TF CASZ1 is a chromosome 1p36 (chr1p36) tumor suppressor. Single-cell RNA sequencing data analyses indicate that CASZ1 is highly expressed in developing chromaffin cells coincident with an expression of NB CRC TFs. In NB tumor cells, the CASZ1 tumor suppressor is silenced while CRC components are highly expressed. We find the NB CRC component HAND2 directly represses CASZ1 expression. ChIP-seq and transcriptomic analyses reveal that restoration of CASZ1 upregulates noradrenergic neuronal genes and represses expression of CRC components by remodeling enhancer activity. Our study identifies that the restored CASZ1 forms a negative feedback regulatory circuit with the established NB CRC to induce noradrenergic neuronal differentiation of NB.

Identification of risk loci for primary aldosteronism in genome-wide association studies

Primary aldosteronism affects up to 10% of hypertensive patients and is responsible for treatment resistance and increased cardiovascular risk. Here we perform a genome-wide association study in a discovery cohort of 562 cases and 950 controls and identify three main loci on chromosomes 1, 13 and X; associations on chromosome 1 and 13 are replicated in a second cohort and confirmed by a meta-analysis involving 1162 cases and 3296 controls. The association on chromosome 13 is specific to men and stronger in bilateral adrenal hyperplasia than aldosterone producing adenoma. Candidate genes located within the two loci, CASZ1 and RXFP2, are expressed in human and mouse adrenals in different cell clusters. Their overexpression in adrenocortical cells suppresses mineralocorticoid output under basal and stimulated conditions, without affecting cortisol biosynthesis. Our study identifies the first risk loci for primary aldosteronism and highlights new mechanisms for the development of aldosterone excess.

Detection of repeat expansions in large next generation DNA and RNA sequencing data without alignment

Bioinformatic methods for detecting short tandem repeat expansions in short-read sequencing have identified new repeat expansions in humans, but require alignment information to identify repetitive motif enrichment at genomic locations. We present superSTR, an ultrafast method that does not require alignment. superSTR is used to process whole-genome and whole-exome sequencing data, and perform the first STR analysis of the UK Biobank, efficiently screening and identifying known and potential disease-associated STRs in the exomes of 49,953 biobank participants. We demonstrate the first bioinformatic screening of RNA sequencing data to detect repeat expansions in humans and mouse models of ataxia and dystrophy.

Exome sequencing in multiplex families with left-sided cardiac defects has high yield for disease gene discovery

Congenital heart disease (CHD) is a common group of birth defects with a strong genetic contribution to their etiology, but historically the diagnostic yield from exome studies of isolated CHD has been low. Pleiotropy, variable expressivity, and the difficulty of accurately phenotyping newborns contribute to this problem. We hypothesized that performing exome sequencing on selected individuals in families with multiple members affected by left-sided CHD, then filtering variants by population frequency, in silico predictive algorithms, and phenotypic annotations from publicly available databases would increase this yield and generate a list of candidate disease-causing variants that would show a high validation rate. In eight of the nineteen families in our study (42%), we established a well-known gene/phenotype link for a candidate variant or performed confirmation of a candidate variant’s effect on protein function, including variants in genes not previously described or firmly established as disease genes in the body of CHD literature: BMP10, CASZ1, ROCK1 and SMYD1. Two plausible variants in different genes were found to segregate in the same family in two instances suggesting oligogenic inheritance. These results highlight the need for functional validation and demonstrate that in the era of next-generation sequencing, multiplex families with isolated CHD can still bring high yield to the discovery of novel disease genes.

Congenital heart disease is a common group of birth defects that are a leading cause of death in children under one year of age. There is strong evidence that genetics plays a role in causing congenital heart disease. While studies using individual cases have identified causative genes for those with a heart defect when accompanied by other birth defects or intellectual disabilities, for individuals who have only a heart defect without other problems, a genetic cause can be found in fewer than 10%. In this study, we enrolled families where there was more than one individual with a heart defect. This allowed us to take advantage of inheritance by searching for potential disease-causing genetic variants in common among all affected individuals in the family. Among 19 families studied, we were able to find a plausible disease-causing variant in eight of them and identified new genes that may cause or contribute to the presence of a heart defect. Two families had potential disease-causing variants in two different genes. We designed assays to test if the variants led to altered function of the protein coded by the gene, demonstrating a functional consequence that support the gene and variant as contributing to the heart defect. These findings show that studying families may be more effective than using individuals to find causes of heart defects. In addition, this family-based method suggests that changes in more than one gene may be required for a heart defect to occur.

Targeting cardiomyocyte proliferation as a key approach of promoting heart repair after injury

Cardiovascular diseases such as myocardial infarction (MI) is a major contributor to human mortality and morbidity. The mammalian adult heart almost loses its plasticity to appreciably regenerate new cardiomyocytes after injuries, such as MI and heart failure. The neonatal heart exhibits robust proliferative capacity when exposed to varying forms of myocardial damage. The ability of the neonatal heart to repair the injury and prevent pathological left ventricular remodeling leads to preserved or improved cardiac function. Therefore, promoting cardiomyocyte proliferation after injuries to reinitiate the process of cardiomyocyte regeneration, and suppress heart failure and other serious cardiovascular problems have become the primary goal of many researchers. Here, we review recent studies in this field and summarize the factors that act upon the proliferation of cardiomyocytes and cardiac repair after injury and discuss the new possibilities for potential clinical treatment strategies for cardiovascular diseases.

A high level of KLF12 causes folic acid-resistant neural tube defects by activating the Shh signaling pathway in mice†

Although adequate periconceptional folic acid (FA) supplementation has reduced the occurrence of pregnancies affected by neural tube defects (NTDs), the mechanisms underlying FA-resistant NTDs are poorly understood, and thus NTDs still remain a global public health concern. A high level of Krüppel-like factor 12 (KLF12) exerts deleterious effects on heath in most cases, but evidence for its roles in development has not been published. We observed KLF12-overexpressing mice showed disturbed neural tube development. KLF12-overexpressing fetuses died in utero at approximately 10.5 days post-coitus, with 100% presenting cranial NTDs. Neither FA nor formate promoted normal neural tube closure in mutant fetuses. The RNA-seq results showed that a high level of KLF12 caused NTDs in mice via overactivating the sonic hedgehog (Shh) signaling pathway, leading to the upregulation of patched 1, GLI-Krüppel family member GLI1, hedgehog-interacting protein, etc., whereas FA metabolism-related enzymes did not express differently. PF-5274857, an antagonist of the Shh signaling pathway, significantly promoted dorsolateral hinge point formation and partially rescued the NTDs. The regulatory hierarchy between a high level of KLF12 and FA-resistant NTDs might provide new insights into the diagnosis and treatment of unexplained NTDs in the future.

A role of Hey2 transcription factor for right ventricle development through regulation of Tbx2-Mycn pathway during cardiac morphogenesis

A basic helix-loop-helix transcription factor Hey2 is expressed in the ventricular myocardium and endocardium of mouse embryos, and Hey2 null mice die perinatally showing ventricular septal defect, dysplastic tricuspid valve and hypoplastic right ventricle. In order to understand region-specific roles of Hey2 during cardiac morphogenesis, we generated Hey2 conditional knockout (cKO) mice using Mef2c-AHF-Cre, which was active in the anterior part of the second heart field and the right ventricle and outflow tract of the heart. Hey2 cKO neonates reproduced three anomalies commonly observed in Hey2 null mice. An earliest morphological defect was the lack of right ventricular extension along the apico-basal axis at midgestational stages. Underdevelopment of the right ventricle was present in all cKO neonates including those without apparent atresia of right-sided atrioventricular connection. RNA sequencing analysis of cKO embryos identified that the gene expression of a non-chamber T-box factor Tbx2 was ectopically induced in the chamber myocardium of the right ventricle. Consistently, mRNA expression of the Mycn transcription factor, which was a cell cycle regulator transcriptionally repressed by Tbx2, was down regulated, and the number of S-phase cells was significantly decreased in the right ventricle of cKO heart. These results suggest that Hey2 plays an important role in right ventricle development during cardiac morphogenesis, at least in part, through mitigating Tbx2-dependent inhibition of Mycn expression.

Causal Genetic Variants in Stillbirth

BACKGROUND

In the majority of cases, the cause of stillbirth remains unknown despite detailed clinical and laboratory evaluation. Approximately 10 to 20% of stillbirths are attributed to chromosomal abnormalities. However, the causal nature of single-nucleotide variants and small insertions and deletions in exomes has been understudied.

METHODS

We generated exome sequencing data for 246 stillborn cases and followed established guidelines to identify causal variants in disease-associated genes. These genes included those that have been associated with stillbirth and strong candidate genes. We also evaluated the contribution of 18,653 genes in case-control analyses stratified according to the degree of depletion of functional variation (described here as "intolerance" to variation).

RESULTS

We identified molecular diagnoses in 15 of 246 cases of stillbirth (6.1%) involving seven genes that have been implicated in stillbirth and six disease genes that are good candidates for phenotypic expansion. Among the cases we evaluated, we also found an enrichment of loss-of-function variants in genes that are intolerant to such variation in the human population (odds ratio, 2.15; 95% confidence interval [CI], 1.46 to 3.06). Loss-of-function variants in intolerant genes were concentrated in genes that have not been associated with human disease (odds ratio, 2.22; 95% CI, 1.41 to 3.34), findings that differ from those in two postnatal clinical populations that were also evaluated in this study.

CONCLUSIONS

Our findings establish the diagnostic utility of clinical exome sequencing to evaluate the role of small genomic changes in stillbirth. The strength of the novel risk signal (as generated through the stratified analysis) was similar to that in known disease genes, which indicates that the genetic cause of stillbirth remains largely unknown. (Funded by the Institute for Genomic Medicine.).

Categorized Genetic Analysis in Childhood-Onset Cardiomyopathy

BACKGROUND

Childhood-onset cardiomyopathy is a heterogeneous group of conditions the cause of which is largely unknown. The influence of consanguinity on the genetics of cardiomyopathy has not been addressed at a large scale.

METHODS

To unravel the genetic cause of childhood-onset cardiomyopathy in a consanguineous population, a categorized approach was adopted. Cases with childhood-onset cardiomyopathy were consecutively recruited. Based on the likelihood of founder mutation and on the clinical diagnosis, genetic test was categorized to either (1) targeted genetic test with targeted mutation test, single-gene test, or multigene panel for Noonan syndrome, or (2) untargeted genetic test with whole-exome sequencing or whole-genome sequencing. Several bioinformatics tools were used to filter the variants.

RESULTS

Two-hundred five unrelated probands with various forms of cardiomyopathy were evaluated. The median age of presentation was 10 months. In 30.2% (n=62), targeted genetic test had a yield of 82.7% compared with 33.6% for whole-exome sequencing/whole-genome sequencing (n=143) giving an overall yield of 53.7%. Strikingly, 96.4% of the variants were homozygous, 9% of which were found in 4 dominant genes. Homozygous variants were also detected in 7 novel candidates (ACACB, AASDH, CASZ1, FLII, RHBDF1, RPL3L, ULK1).

CONCLUSIONS

Our work demonstrates the impact of consanguinity on the genetics of childhood-onset cardiomyopathy, the value of adopting a categorized population-sensitive genetic approach, and the opportunity of uncovering novel genes. Our data suggest that if a founder mutation is not suspected, adopting whole-exome sequencing/whole-genome sequencing as a first-line test should be considered.

Knockdown of lincRNA PADNA promotes bupivacaine-induced neurotoxicity by miR-194/FBXW7 axis

BACKGROUND

The aim of the study was to explore the function and mechanism of lincRNA PADNA in bupivacaine-induced neurotoxicity.

METHODS

Mouse DRG neurons were cultured in vitro and treated with bupivacaine to establish a neurotoxicity model. Caspase3 activity, cell viability, and TUNEL assays were analyzed to assess the role of lincRNA PADNA. A dual-luciferase reporter assay was used to determine the binding target of lincRNA PANDA.

RESULTS

The expression of lincRNA PADNA was significantly increased with increasing concentrations of bupivacaine. Functional analysis revealed that knockdown of lincRNA PADNA increased caspase3 activity and inhibited cell viability. Western blot analysis showed that knockdown of lincRNA PADNA promoted cleaved caspase3 levels. We also revealed that lincRNA PADNA may bind with miR-194. Knockdown of miR-194 rescued the function of lincRNA PADNA, suggesting that lincRNA PADNA may sponge miR-194. In addition, we provided new evidence that the lincRNA PADNA/miR-194/FBXW7 axis plays an important role in the neurotoxicity process.

CONCLUSION

We performed comprehensive experiments to verify the function and mechanism of lincRNA PADNA in bupivacaine-induced neurotoxicity. Our study provides new evidence and clues for the prevention of neurotoxicity.

CASZ1 induces skeletal muscle and rhabdomyosarcoma differentiation through a feed-forward loop with MYOD and MYOG

Embryonal rhabdomyosarcoma (ERMS) is a childhood cancer that expresses myogenic master regulatory factor MYOD but fails to differentiate. Here, we show that the zinc finger transcription factor CASZ1 up-regulates MYOD signature genes and induces skeletal muscle differentiation in normal myoblasts and ERMS. The oncogenic activation of the RAS-MEK pathway suppresses CASZ1 expression in ERMS. ChIP-seq, ATAC-seq and RNA-seq experiments reveal that CASZ1 directly up-regulates skeletal muscle genes and represses non-muscle genes through affecting regional epigenetic modifications, chromatin accessibility and super-enhancer establishment. Next generation sequencing of primary RMS tumors identified a single nucleotide variant in the CASZ1 coding region that potentially contributes to ERMS tumorigenesis. Taken together, loss of CASZ1 activity, due to RAS-MEK signaling or genetic alteration, impairs ERMS differentiation, contributing to RMS tumorigenesis.

Transcriptome analysis defines myocardium gene signatures in children with ToF and ASD and reveals disease-specific molecular reprogramming in response to surgery with cardiopulmonary bypass

BACKGROUND

Tetralogy of Fallot (ToF) and Atrial Septal Defects (ASD) are the most common types of congenital heart diseases and a major cause of childhood morbidity and mortality. Cardiopulmonary bypass (CPB) is used during corrective cardiac surgery to support circulation and heart stabilization. However, this procedure triggers systemic inflammatory and stress response and consequent increased risk of postoperative complications. The aim of this study was to define the molecular bases of ToF and ASD pathogenesis and response to CPB and identify new potential biomarkers.

METHODS

Comparative transcriptome analysis of right atrium specimens collected from 10 ToF and 10 ASD patients was conducted before (Pre-CPB) and after (Post-CPB) corrective surgery. Total RNA isolated from each sample was individually hybridized on Affymetrix HG-U133 Plus Array Strips containing 38,500 unique human genes. Differences in the gene expression profiles and functional enrichment/network analyses were assessed using bioinformatic tools. qRT-PCR analysis was used to validate gene modulation.

RESULTS

Pre-CPB samples showed significant differential expression of a total of 72 genes, 28 of which were overexpressed in ToF and 44 in ASD. According to Gene Ontology annotation, the mostly enriched biological processes were represented by matrix organization and cell adhesion in ToF and by muscle development and contractility in ASD specimens. GSEA highlighted the specific enrichment of hypoxia gene sets in ToF samples, pointing to a role for hypoxia in disease pathogenesis. The post-CPB myocardium exhibited significant alterations in the expression profile of genes related to transcription regulation, growth/apoptosis, inflammation, adhesion/matrix organization, and oxidative stress. Among them, only 70 were common to the two disease groups, whereas 110 and 24 were unique in ToF and ASD, respectively. Multiple functional interactions among differentially expressed gene products were predicted by network analysis. Interestingly, gene expression changes in ASD samples followed a consensus hypoxia profile.

CONCLUSION

Our results provide a comprehensive view of gene reprogramming in right atrium tissues of ToF and ASD patients before and after CPB, defining specific molecular pathways underlying disease pathophysiology and myocardium response to CPB. These findings have potential translational value because they identify new candidate prognostic markers and targets for tailored cardioprotective post-surgical therapies.

Epigenome-wide base-resolution profiling of DNA methylation in chorionic villi of fetuses with Down syndrome by methyl-capture sequencing

BACKGROUND

Epigenetic mechanisms provide an interface between environmental factors and the genome and are influential in various diseases. These mechanisms, including DNA methylation, influence the regulation of development, differentiation, and establishment of cellular identity. Here, we performed high-throughput methylome profiling to determine whether differential patterns of DNA methylation correlate with Down syndrome (DS).

MATERIALS AND METHODS

We extracted DNA from the chorionic villi cells of five normal and five DS fetuses at the early developmental stage (12-13 weeks of gestation). Methyl-capture sequencing (MC-Seq) was used to investigate the methylation levels of CpG sites distributed across the whole genome to identify differentially methylated CpG sites (DMCs) and regions (DMRs) in DS. New functional annotations of DMR genes using bioinformatics tools were predicted.

RESULTS

DNA hypermethylation was observed in DS fetal chorionic villi cells. Significant differences were evident for 4,439 DMCs, including hypermethylation (n = 4,261) and hypomethylation (n = 178). Among them, 140 hypermethylated DMRs and only 1 hypomethylated DMR were located on 121 genes and 1 gene, respectively. One hundred twenty-two genes, including 141 DMRs, were associated with heart morphogenesis and development of the ear, thyroid gland, and nervous systems. The genes were significantly associated with DS and various diseases, including hepatopulmonary syndrome, conductive hearing loss, holoprosencephaly, heart diseases, glaucoma, and musculoskeletal abnormalities.

CONCLUSIONS

This is the first study to compare the whole-epigenome DNA methylation pattern of the chorionic villi cells from normal and DS fetuses at the early developmental-stage using MC-seq. Overall, our results indicate that the chorionic villi cells of DS fetuses are hypermethylated in all autosomes and suggested that altered DNA methylation may be a recurrent and functionally relevant downstream response to DS in human cells. This study provides basic information for future research focused on the pathophysiology of the DS and its potential effects, as well as the role DNA methylation plays in the early developmental stage of DS fetuses.

A novel de novo CASZ1 heterozygous frameshift variant causes dilated cardiomyopathy and left ventricular noncompaction cardiomyopathy

Background

Dilated cardiomyopathy (DCM) is the most common cardiomyopathy with a common presentation of heart failure. It has been reported that CASZ1 loss‐of‐function mutation contributes to familial DCM and congenital ventricular septal defect (VSD). To date, only two pathogenic variants in CASZ1 have been previously reported worldwide.

Methods

To identify the causative variant in an 11‐month‐old Chinese boy with DCM and left ventricular noncompaction cardiomyopathy (LVNC), trio‐whole‐exome sequencing was performed followed by mutational analysis and Sanger sequencing.

Results

An unreported de novo heterozygous frameshift variant (c.2443_2459delGTGGGCACCCCCAGCCT, p.Val815Profs*14) in CASZ1 was idenitified in the proband. The frameshift mutation in CASZ1 not only led to DCM but also presented an LVNC phenotype.

Conclusion

We have identified a novel CASZ1 variant in a patient with combined DCM and LVNC for the first time, thus broadening the phenotypic spectrum of CASZ1 variants. Furthermore, this study emphasized the usefulness of whole‐exome sequencing for genetic diagnosis of cardiomyopathy.

Casz1 controls higher-order nuclear organization in rod photoreceptors

Eukaryotic cells depend on precise genome organization within the nucleus to maintain an appropriate gene-expression profile. Critical to this process is the packaging of functional domains of open and closed chromatin to specific regions of the nucleus, but how this is regulated remains unclear. In this study, we show that the zinc finger protein Casz1 regulates higher-order nuclear organization of rod photoreceptors in the mouse retina by repressing nuclear lamina function, which leads to central localization of heterochromatin. Loss of Casz1 in rods leads to an abnormal transcriptional profile followed by degeneration. These results identify Casz1 as a regulator of higher-order genome organization.

Genome organization plays a fundamental role in the gene-expression programs of numerous cell types, but determinants of higher-order genome organization are poorly understood. In the developing mouse retina, rod photoreceptors represent a good model to study this question. They undergo a process called “chromatin inversion” during differentiation, in which, as opposed to classic nuclear organization, heterochromatin becomes localized to the center of the nucleus and euchromatin is restricted to the periphery. While previous studies showed that the lamin B receptor participates in this process, the molecular mechanisms regulating lamina function during differentiation remain elusive. Here, using conditional genetics, we show that the zinc finger transcription factor Casz1 is required to establish and maintain the inverted chromatin organization of rod photoreceptors and to safeguard their gene-expression profile and long-term survival. At the mechanistic level, we show that Casz1 interacts with the polycomb repressor complex in a splice variant-specific manner and that both are required to suppress the expression of the nuclear envelope intermediate filament lamin A/C in rods. Lamin A is in turn sufficient to regulate heterochromatin organization and nuclear position. Furthermore, we show that Casz1 is sufficient to expand and centralize the heterochromatin of fibroblasts, suggesting a general role for Casz1 in nuclear organization. Together, these data support a model in which Casz1 cooperates with polycomb to control rod genome organization, in part by silencing lamin A/C.

Potential Common Pathogenic Pathways for the Left Ventricular Noncompaction Cardiomyopathy (LVNC)

Ventricular trabeculation and compaction are two essential morphogenetic events for generating a functionally competent ventricular wall. A significant reduction in trabeculation is usually associated with hypoplastic wall and ventricular compact zone deficiencies, which commonly leads to embryonic heart failure and early embryonic lethality. In contrast, the arrest of ventricular wall compaction (noncompaction) is believed to be causative to the left ventricular noncompaction (LVNC), a genetically heterogeneous disorder and the third most common cardiomyopathy among pediatric patients. After critically reviewing recent findings from genetically engineered mouse models, we suggest a model which proposes that defects in myofibrillogenesis and polarization in trabecular cardiomyocytes underly the common pathogenic mechanism for ventricular noncompaction.

Zinc and Zinc Transporters: Novel Regulators of Ventricular Myocardial Development

Ventricular myocardial development is a well-orchestrated process involving different cardiac structures, multiple signal pathways, and myriad proteins. Dysregulation of this important developmental event can result in cardiomyopathies, such as left ventricle non-compaction, which affect the pediatric population and the adults. Human and mouse studies have shed light upon the etiology of some cardiomyopathy cases and highlighted the contribution of both genetic and environmental factors. However, the regulation of ventricular myocardial development remains incompletely understood. Zinc is an essential trace metal with structural, enzymatic, and signaling function. Perturbation of zinc homeostasis has resulted in developmental and physiological defects including cardiomyopathy. In this review, we summarize several mechanisms by which zinc and zinc transporters can impact the regulation of ventricular myocardial development. Based on our review, we propose that zinc deficiency and mutations of zinc transporters may underlie some cardiomyopathy cases especially those involving ventricular myocardial development defects.

Zeb1-Hdac2-eNOS circuitry identifies early cardiovascular precursors in naive mouse embryonic stem cells

Nitric oxide (NO) synthesis is a late event during differentiation of mouse embryonic stem cells (mESC) and occurs after release from serum and leukemia inhibitory factor (LIF). Here we show that after release from pluripotency, a subpopulation of mESC, kept in the naive state by 2i/LIF, expresses endothelial nitric oxide synthase (eNOS) and endogenously synthesizes NO. This eNOS/NO-positive subpopulation (ESNO+) expresses mesendodermal markers and is more efficient in the generation of cardiovascular precursors than eNOS/NO-negative cells. Mechanistically, production of endogenous NO triggers rapid Hdac2 S-nitrosylation, which reduces association of Hdac2 with the transcriptional repression factor Zeb1, allowing mesendodermal gene expression. In conclusion, our results suggest that the interaction between Zeb1, Hdac2, and eNOS is required for early mesendodermal differentiation of naive mESC.

Downregulation of castor zinc finger 1 predicts poor prognosis and facilitates hepatocellular carcinoma progression via MAPK/ERK signaling

Background

Castor zinc finger 1 (CASZ1) plays critical roles in various biological processes and pathologic conditions, including cancer. However, the prognostic importance and biologic functions of CASZ1 in hepatocellular carcinoma (HCC) are still unclear.

Methods

qRT-PCR, western blot and immunohistochemistry analyses were used to determine CASZ1 expression in HCC samples and cell lines. The clinical significance of CASZ1 was assessed in two independent study cohorts containing 232 patients with HCC. A series of in vitro and in vivo experiments were performed to explore the role and molecular mechanism of CASZ1 in HCC progression.

Results

Here we report that CASZ1 expression was downregulated in HCC tissues and cell lines. Low CASZ1 expression was closely correlated with aggressive clinicopathological features, poor clinical outcomes and early recurrence of HCC patients. Moreover, overexpression of CASZ1 in HCCLM3 cells significantly inhibited cell proliferation, migration, invasion in vitro and tumor growth and metastasis in vivo, whereas silencing CASZ1 significantly enhanced the above abilities of PLC/PRF/5 cells. Further mechanism study indicated that these phenotypic changes were mediated by MAPK/ERK signaling pathway and involved altered expression of MMP2, MMP9 and cyclinD1. Finally, we proved that CASZ1 exerted its tumor-suppressive effect by directly interacting with RAF1 and reducing the protein stability of RAF1.

Conclusions

Our study for the first time demonstrated that CASZ1 is a tumor suppressor in HCC, which may serve as a novel prognostic predictor and therapeutic target for HCC patients.

Electronic supplementary material

The online version of this article (10.1186/s13046-018-0720-8) contains supplementary material, which is available to authorized users.

Electrically Driven Microengineered Bioinspired Soft Robots

To create life-like movements, living muscle actuator technologies have borrowed inspiration from biomimetic concepts in developing bioinspired robots. Here, the development of a bioinspired soft robotics system, with integrated self-actuating cardiac muscles on a hierarchically structured scaffold with flexible gold microelectrodes is reported. Inspired by the movement of living organisms, a batoid-fish-shaped substrate is designed and reported, which is composed of two micropatterned hydrogel layers. The first layer is a poly(ethylene glycol) hydrogel substrate, which provides a mechanically stable structure for the robot, followed by a layer of gelatin methacryloyl embedded with carbon nanotubes, which serves as a cell culture substrate, to create the actuation component for the soft body robot. In addition, flexible Au microelectrodes are embedded into the biomimetic scaffold, which not only enhance the mechanical integrity of the device, but also increase its electrical conductivity. After culturing and maturation of cardiomyocytes on the biomimetic scaffold, they show excellent myofiber organization and provide self-actuating motions aligned with the direction of the contractile force of the cells. The Au microelectrodes placed below the cell layer further provide localized electrical stimulation and control of the beating behavior of the bioinspired soft robot.

Identification of Casz1 as a Regulatory Protein Controlling T Helper Cell Differentiation, Inflammation, and Immunity

While T helper (Th) cells play a crucial role in host defense, an imbalance in Th effector subsets due to dysregulation in their differentiation and expansion contribute to inflammatory disorders. Here, we show that Casz1, whose function is previously unknown in CD4+ T cells, coordinates Th differentiation in vitro and in vivo. Casz1 deficiency in CD4+ T cells lowers susceptibility to experimental autoimmune encephalomyelitis, consistent with the reduced frequency of Th17 cells, despite an increase in Th1 cells in mice. Loss of Casz1 in the context of mucosal Candida infection severely impairs Th17 and Treg responses, and lowers the ability of the mice to clear the secondary infection. Importantly, in both the models, absence of Casz1 causes a significant diminution in IFN-γ+IL-17A+ double-positive inflammatory Th17 cells (Th1* cells) in tissues in vivo. Transcriptome analyses of CD4+ T cells lacking Casz1 show a signature consistent with defective Th17 differentiation. With regards to Th17 differentiation, Casz1 limits repressive histone marks and enables acquisition of permissive histone marks at Rorc, Il17a, Ahr, and Runx1 loci. Taken together, these data identify Casz1 as a new Th plasticity regulator having important clinical implications for autoimmune inflammation and mucosal immunity.

Cardiomyopathies Due to Left Ventricular Noncompaction, Mitochondrial and Storage Diseases, and Inborn Errors of Metabolism

The normal function of the human myocardium requires the proper generation and utilization of energy and relies on a series of complex metabolic processes to achieve this normal function. When metabolic processes fail to work properly or effectively, heart muscle dysfunction can occur with or without accompanying functional abnormalities of other organ systems, particularly skeletal muscle. These metabolic derangements can result in structural, functional, and infiltrative deficiencies of the heart muscle. Mitochondrial and enzyme defects predominate as disease-related etiologies. In this review, left ventricular noncompaction cardiomyopathy, which is often caused by mutations in sarcomere and cytoskeletal proteins and is also associated with metabolic abnormalities, is discussed. In addition, cardiomyopathies resulting from mitochondrial dysfunction, metabolic abnormalities, storage diseases, and inborn errors of metabolism are described.

Formation of a TBX20-CASZ1 protein complex is protective against dilated cardiomyopathy and critical for cardiac homeostasis

By the age of 40, one in five adults without symptoms of cardiovascular disease are at risk for developing congestive heart failure. Within this population, dilated cardiomyopathy (DCM) remains one of the leading causes of disease and death, with nearly half of cases genetically determined. Though genetic and high throughput sequencing-based approaches have identified sporadic and inherited mutations in a multitude of genes implicated in cardiomyopathy, how combinations of asymptomatic mutations lead to cardiac failure remains a mystery. Since a number of studies have implicated mutations of the transcription factor TBX20 in congenital heart diseases, we investigated the underlying mechanisms, using an unbiased systems-based screen to identify novel, cardiac-specific binding partners. We demonstrated that TBX20 physically and genetically interacts with the essential transcription factor CASZ1. This interaction is required for survival, as mice heterozygous for both Tbx20 and Casz1 die post-natally as a result of DCM. A Tbx20 mutation associated with human familial DCM sterically interferes with the TBX20-CASZ1 interaction and provides a physical basis for how this human mutation disrupts normal cardiac function. Finally, we employed quantitative proteomic analyses to define the molecular pathways mis-regulated upon disruption of this novel complex. Collectively, our proteomic, biochemical, genetic, and structural studies suggest that the physical interaction between TBX20 and CASZ1 is required for cardiac homeostasis, and further, that reduction or loss of this critical interaction leads to DCM. This work provides strong evidence that DCM can be inherited through a digenic mechanism.

A molecular understanding of cardiomyocyte development is an essential goal for improving clinical approaches to CHD. While TBX20 is an essential transcription factor for heart development and its disease relevance is well established, many fundamental questions remain about the mechanism of TBX20 function. Principle among these is how TBX20 mutations associated with adult dilated cardiomyopathy circumvent (DCM) the essential embryonic requirement for TBX20 in heart development. Here we report using an integrated approach that TBX20 complexes with the cardiac transcription factor CASZ1 in vivo. We confirmed TBX20 and CASZ1 interact biochemically and genetically, and show mice heterozygous for both Tbx20 and Casz1 die, beginning at 4 to 8 weeks post birth, exhibiting hallmarks of DCM. Interestingly, the human mutant TBX20^F256I bypasses the early essential requirement for TBX20 but leads to DCM. We report here that TBX20^F256I disrupts the TBX20-CASZ1 interaction, ascribing clinical relevance to this protein complex. Further, by using quantitative proteomics we have identified the molecular pathways altered in TBX20-CASZ1-mediated DCM. Together, these results identify a novel interaction between TBX20 and CASZ1 that is essential for maintaining cardiac homeostasis and imply that DCM can be inherited through a digenic mechanism.

Foxa2 identifies a cardiac progenitor population with ventricular differentiation potential

The recent identification of progenitor populations that contribute to the developing heart in a distinct spatial and temporal manner has fundamentally improved our understanding of cardiac development. However, the mechanisms that direct atrial versus ventricular specification remain largely unknown. Here we report the identification of a progenitor population that gives rise primarily to cardiovascular cells of the ventricles and only to few atrial cells (<5%) of the differentiated heart. These progenitors are specified during gastrulation, when they transiently express Foxa2, a gene not previously implicated in cardiac development. Importantly, Foxa2+ cells contribute to previously identified progenitor populations in a defined pattern and ratio. Lastly, we describe an analogous Foxa2+ population during differentiation of embryonic stem cells. Together, these findings provide insight into the developmental origin of ventricular and atrial cells, and may lead to the establishment of new strategies for generating chamber-specific cell types from pluripotent stem cells.

CASZ1 loss-of-function mutation contributes to familial dilated cardiomyopathy

Background:

The zinc finger transcription factor CASZ1 plays a key role in cardiac development and postnatal adaptation, and in mice, deletion of the

Methods:

The coding exons and splicing junction sites of the

Results:

A novel heterozygous CASZ1 mutation, p.K351X, was identified in an index patient with DCM. Genetic analysis of the mutation carrier’s family showed that the mutation co-segregated with DCM, which was transmitted in an autosomal dominant pattern with complete penetrance. The nonsense mutation, which was absent in 400 referential chromosomes, altered the amino acid that was highly conserved evolutionarily. Biological investigations revealed that the mutant CASZ1 had no transcriptional activity.

Conclusions:

The current study reveals

Transcription Factor Drug Targets

Transcription factors represent the point of convergence of multiple signaling pathways within eukaryotic cells. Deregulated transcription factors contribute to the pathogenesis of a plethora of human diseases, ranging from diabetes, inflammatory disorders and cardiovascular disease to many cancers, and thus these proteins hold great therapeutic potential. Direct modulation of transcription factor function by small molecules is no longer regarded a Sisyphean task, as recent work in drug discovery has revealed that transcription factors are amenable to drug inhibition. Here in we summarize, recent advances regarding the significance of transcription factors in human diseases and we discuss emerging pharmacological strategies to modulate transcription factor function. J. Cell. Biochem. 117: 2693-2696, 2016. © 2016 Wiley Periodicals, Inc.

[An updated review of 1p36 deletion (monosomy) syndrome]

The Monosomy 1p36 deletion syndrome is part of the group of diseases known as Rare Diseases. The objective of the present work is to review the characteristics of Monosomy 1p36 deletion syndrome. The monosomy 1p36 deletion syndrome phenotype includes: dysmorphic craniofacial features; large anterior fontanelle, unibrow, deep-set eyes, epicanthus, wide nasal root/bridge, mandible hypoplasia, abnormal location of the pinna, philtrum and pointed chin; neurological alterations: seizures and hydrocephalus (in some cases). Cerebral malformations: ventricular hypertrophy, increased subarachnoid space, morphological alterations of corpus callosum, cortical atrophy, delays in myelinisation, periventricular leukomalacia and periventricular heterotopia. These alterations produce intellectual disability and delays in motor growth, communication skills, language, social and adaptive behaviour. It is Hearing and vision impairments are also observed in subjects with this syndrome, as well as alterations of cardiac, endocrine and urinary systems and alterations at skin and skeletal level.

CONCLUSIONS

Approximately 100 cases have been documented since 1981. This rare disease is the most common subtelomeric-micro-deletion syndrome. In situ hybridization with fluorescence (FISH) and array-comparative genomic hybridization (CGH-array) are at present the two best diagnostic techniques. There is currently no effective medical treatment for this disease.

CASZ1 loss-of-function mutation associated with congenital heart disease

As the most common form of birth defect in humans, congenital heart disease (CHD) is associated with substantial morbidity and mortality in both children and adults. Increasing evidence demonstrates that genetic defects play a pivotal role in the pathogenesis of CHD. However, CHD is of great heterogeneity, and in an overwhelming majority of cases, the genetic determinants underpinning CHD remain elusive. In the present investigation, the coding exons and flanking introns of the CASZ1 gene, which codes for a zinc finger transcription factor essential for the cardiovascular morphogenesis, were sequenced in 172 unrelated patients with CHD. As a result, a novel heterozygous CASZ1 mutation, p.L38P, was identified in an index patient with congenital ventricular septal defect (VSD). Genetic scanning of the mutation carrier's available family members revealed that the mutation was present in all affected patients but absent in unaffected individuals. Analysis of the proband's pedigree showed that the mutation co-segregated with VSD, which was transmitted as an autosomal dominant trait with complete penetrance. The missense mutation, which altered the amino acid that was highly conserved evolutionarily, was absent in 200 unrelated, ethnically-matched healthy subjects used as controls. Functional deciphers by using a dual-luciferase reporter assay system unveiled that the mutant CASZ1 had significantly reduced transcriptional activity as compared with its wild-type counterpart. To the best of our knowledge, the current study firstly identifies CASZ1 as a new gene predisposing to CHD in humans, which provides novel insight into the molecular mechanisms underlying CHD and a potential therapeutic target for CASZ1-associated CHD, suggesting potential implications for personalized prophylaxis and therapy of CHD.

Anacardic acid and thyroid hormone enhance cardiomyocytes production from undifferentiated mouse ES cells along functionally distinct pathways

The epigenetics of early commitment to embryonal cardiomyocyte is poorly understood. In this work, we compared the effect of thyroid hormone and that of anacardic acid, a naturally occurring histone acetylase inhibitor, or both in combination, on mouse embryonic stem cells (mES) differentiating into embryonal cardiomyocyte by embryoid bodies (EBs) formation. Although the results indicated that anacardic acid (AA) and thyroid hormone were both efficient in promoting cardiomyocyte differentiation, we noticed that a transient exposure of mES to AA alone was sufficient to enlarge the beating areas of EBs compared to those of untreated controls. This effect was associated with changes in the chromatin structure at the promoters of specific cardiomyogenic genes. Among them, a rapid induction of the transcription factor Castor 1 (CASZ1), important for cardiomyocytes differentiation and maturation during embryonic development, was observed in the presence of AA. In contrast, thyroid hormone (T 3) was more effective in stimulating spontaneous firing, thus suggesting a role in the production of a population of cardiomyocyte with pacemaker properties. In conclusion, AA and thyroid hormone both enhanced cardiomyocyte formation along in apparently distinct pathways.

Zinc finger transcription factor CASZ1 interacts with histones, DNA repair proteins and recruits NuRD complex to regulate gene transcription

The zinc finger transcription factor CASZ1 has been found to control neural fate-determination in flies, regulate murine and frog cardiac development, control murine retinal cell progenitor expansion and function as a tumor suppressor gene in humans. However, the molecular mechanism by which CASZ1 regulates gene transcription to exert these diverse biological functions has not been described. Here we identify co-factors that are recruited by CASZ1b to regulate gene transcription using co-immunoprecipitation (co-IP) and mass spectrometry assays. We find that CASZ1b binds to the nucleosome remodeling and histone deacetylase (NuRD) complex, histones and DNA repair proteins. Mutagenesis of the CASZ1b protein assay demonstrates that the N-terminus of CASZ1b is required for NuRD binding, and a poly(ADP-ribose) binding motif in the CASZ1b protein is required for histone H3 and DNA repair proteins binding. The N-terminus of CASZ1b fused to an artificial DNA-binding domain (GAL4DBD) causes a significant repression of transcription (5xUAS-luciferase assay), which could be blocked by treatment with an HDAC inhibitor. Realtime PCR results show that the transcriptional activity of CASZ1b mutants that abrogate NuRD or histone H3/DNA binding is significantly decreased. This indicates a model in which CASZ1b binds to chromatin and recruits NuRD complexes to orchestrate epigenetic-mediated transcriptional programs.

Identification of CASZ1 NES reveals potential mechanisms for loss of CASZ1 tumor suppressor activity in neuroblastoma

As a transcription factor, localization to the nucleus and the recruitment of cofactors to regulate gene transcription is essential. Nuclear localization and nucleosome remodeling and histone deacetylase (NuRD) complex binding are required for the zinc-finger transcription factor CASZ1 to function as a neuroblastoma (NB) tumor suppressor. However, the critical amino acids (AAs) that are required for CASZ1 interaction with NuRD complex and the regulation of CASZ1 subcellular localization have not been characterized. Through alanine scanning, immunofluorescence cell staining and co-immunoprecipitation, we define a critical region at the CASZ1 N terminus (AAs 23-40) that mediates the CASZ1b nuclear localization and NuRD interaction. Furthermore, we identified a nuclear export signal (NES) at the N terminus (AAs 176-192) that contributes to CASZ1 nuclear-cytoplasmic shuttling in a chromosomal maintenance 1-dependent manner. An analysis of CASZ1 protein expression in a primary NB tissue microarray shows that high nuclear CASZ1 staining is detected in tumor samples from NB patients with good prognosis. In contrast, cytoplasmic-restricted CASZ1 staining or low nuclear CASZ1 staining is found in tumor samples from patients with poor prognosis. These findings provide insight into mechanisms by which CASZ1 regulates transcription, and suggests that regulation of CASZ1 subcellular localization may impact its function in normal development and pathologic conditions such as NB tumorigenesis.

CASZ1 is a novel promoter of metastasis in ovarian cancer

Epithelial ovarian cancer (EOC) carries the highest mortality rate of all gynecologic malignancies. This high mortality rate is attributed to the fact that most cases of ovarian cancer are detected at late stages when metastases are already present. Through microarray analysis, we previously demonstrated that castor zinc finger 1 (CASZ1) is up-regulated in EOC cells. In contrast to its role in EOC, CASZ1 functions a tumor suppressor in neuroblastoma. Human CASZ1 is predominantly expressed in 2 alternatively spliced isoforms: CASZ1a and CASZ1b. In the present study, we investigated the role of CASZ1 in ovarian cancer cell migration and invasion and assessed the value of CASZ1 expression as a prognostic indicator of metastasis in human ovarian cancer. We used a lentivirus expressing CASZ1-shRNA and a plasmid expressing CASZ1 from a CMV promoter to knockdown and overexpress CASZ1, respectively, in the MCAS, RMUG-S, TOV21G, and A2780(CP70) ovarian cancer cell lines. mRNA expression levels in tumor tissues and cell lines were measured using quantitative real-time PCR, and CASZ1 protein expression in EOC and paired metastatic tumor tissues was analyzed using immunohistochemistry. We found that CASZ1 was highly expressed in EOC tissues and ovarian cancer cell lines and that CASZ1 knockdown suppressed cell migration and invasion in EOC cells. CASZ1a and CASZ1b exerted similar effects on cell migration and invasion in EOC cells. In addition, CASZ1 promoted the epithelial-mesenchymal transition in EOC cells, and CASZ1 knockdown suppressed cancer metastasis in vivo. Furthermore, CASZ1 protein levels were elevated in human metastatic ovarian tumor tissues. Together, these results indicate that CASZ1 is a novel promoter of EOC metastasis and is highly up-regulated in metastatic EOC tumors.