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Background: A peculiar subgroup of patients with partial or complete atrioventricular canal defect exhibits a spectrum of left‐sided obstructions including right ventricular dominance and aortic coarctation. The association of atrioventricular canal defect with left‐sided obstructions is found in several genetic syndromes; however, the molecular basis of nonsyndromic atrioventricular canal defect with aortic coarctation is still poorly understood. Although some candidate genes for nonsyndromic atrioventricular canal defect are known, a complex oligogenic inheritance determined in some cases by the co‐occurrence of multiple variants has also been hypothesized. Case Report: We describe a nonsyndromic infant with mesocardia with viscero‐atrial situs solitus, partial atrioventricular canal defect, mild right ventricular dominance, and coarctation of the aorta. Next generation sequencing genetic testing revealed variants in two genes, GDF1 and NOTCH1, previously reported in association with atrioventricular canal defect and left‐sided obstructive lesions, respectively. Conclusion: The present report could support the hypothesis that the co‐occurrence of cumulative variants may be considered as genetic predisposing risk factor for specific congenital heart defects. [ABSTRACT FROM AUTHOR]

Extracellular factors belonging to the TGF-β family play pivotal roles in the formation and patterning of germ layers during early Xenopus embryogenesis. Here, we show that the vg1 and nodal3 genes of Xenopus laevis are present in gene clusters on chromosomes XLA1L and XLA3L, respectively, and that both gene clusters have been completely lost from the syntenic S chromosome regions. The presence of gene clusters and chromosome-specific gene loss were confirmed by cDNA FISH analyses. Sequence and expression analyses revealed that paralogous genes in the vg1 and nodal3 clusters on the L chromosomes were also altered compared to their Xenopus tropicalis orthologs. X. laevis vg1 and nodal3 paralogs have potentially become pseudogenes or sub-functionalized genes and are expressed at different levels. As X. tropicalis has a single vg1 gene on chromosome XTR1, the ancestral vg1 gene in X. laevis appears to have been expanded on XLA1L. Of note, two reported vg1 genes, vg1(S20) and vg1(P20), reside in the cluster on XLA1L. The nodal3 gene cluster is also present on X. tropicalis chromosome XTR3, but phylogenetic analysis indicates that nodal3 genes in X. laevis and X. tropicalis were independently expanded and/or evolved in concert within each cluster by gene conversion. These findings provide insights into the function and molecular evolution of TGF-β family genes in response to allotetraploidization.

The genetic basis of congenital heart malformations associated with disruption of left–right (L–R) asymmetry is broad and heterogenous, with variants in over 25 genes implicated thus far. Of these, deleterious variants in the Growth/Differentiation Factor 1 (GDF1) gene have been shown to cause heterotaxy with varied complex heart malformations of left–right patterning, in 23 individuals reported to date, either in monoallelic or biallelic state. We report three unrelated individuals exhibiting right isomerism with congenital heart defects, each originating from a consanguineous kindred of Arab‐Muslim descent. Using whole exome sequencing, a shared novel homozygous truncating c.608G > A (p.W203*) variant in the GDF1 gene was revealed as the molecular basis of their disease. Subsequently, targeted sequencing of this variant showed full segregation with the disease in these families, with a total of over 15 reportedly affected individuals, enabling genetic counseling, prenatal diagnosis, and planning of future pregnancies. Our findings further confirm the association of biallelic GDF1 variants, heterotaxy and congenital heart defects of left–right patterning, and expand the previously described phenotypic spectrum and mutational profile. Moreover, we suggest targeted screening for the p.W203* variant in relevant clinical circumstances. [ABSTRACT FROM AUTHOR]

Background: Growth and differentiation factor 15 (GDF15) has been proved to regulate the process of Myocardial ischemia-reperfusion injury (MIRI), which is a serious complication of reperfusion therapy. The present study aimed to explore if GDF15 could regulate the MIRI-induced ferroptosis., Method: MIRI animal model was established by ligating the left anterior descending coronary artery. Oxygen-glucose deprivation/reoxygenation (OGD/R) cell model was established to imitate MIRI in vitro . The indicators of ferroptosis including mitochondrial damage, GPX4, FACL4, XCT4, and oxidative stress markers were evaluated., Results: Overexpression of GDF15 greatly inhibited MIRI, improved cardiac function, alleviated MIRI-induced ferroptosis. pc-DNA-GDF15 significantly inhibited the oxidative stress condition and inflammation response. The OGD/R-induced ferroptosis was also inhibited by pc-DNA-GDF15., Conclusion: We proved that the MIRI-induced ferroptosis could by inhibited by pc-DNA-GDF15 through evaluating mitochondrial damage, MDA, GSH, and GSSG. Our research provides a new insight for the prevention and treatment of MIRI, and a new understanding for the mechanism of MIRI-induced ferroptosis.

Tetralogy of Fallot (TOF) and double-outlet right ventricle (DORV) are conotruncal defects resulting from disturbances of the second heart field and the neural crest, which can occur as isolated malformations or as part of multiorgan syndromes. Their etiology is multifactorial and characterized by overlapping genetic causes. In this chapter, we present the different genetic alterations underlying the two diseases, which range from chromosomal abnormalities like aneuploidies and structural mutations to rare single nucleotide variations affecting distinct genes. For example, mutations in the cardiac transcription factors NKX2-5, GATA4, and HAND2 have been identified in isolated TOF cases, while mutations of TBX5 and 22q11 deletion, leading to haploinsufficiency of TBX1, cause Holt-Oram and DiGeorge syndrome, respectively. Moreover, genes involved in signaling pathways, laterality determination, and epigenetic mechanisms have also been found mutated in TOF and/or DORV patients. Finally, genome-wide association studies identified common single nucleotide polymorphisms associated with the risk for TOF., (© 2024. The Author(s), under exclusive license to Springer Nature Switzerland AG.)

Defects of situs are associated with complex sets of congenital heart defects in which the normal concordance of asymmetric thoracic and abdominal organs is disturbed. The cellular and molecular mechanisms underlying the formation of the embryonic left-right axis have been investigated extensively in the past decade. This has led to the identification of mutations in at least 33 different genes in humans with heterotaxy and situs defects. Those mutations affect a broad range of molecular components, from transcription factors, signaling molecules, and chromatin modifiers to ciliary proteins. A substantial overlap of these genes is observed with genes associated with other congenital heart diseases such as tetralogy of Fallot and double-outlet right ventricle, d-transposition of the great arteries, and atrioventricular septal defects. In this chapter, we present the broad genetic heterogeneity of situs defects including recent human genomics efforts., (© 2024. The Author(s), under exclusive license to Springer Nature Switzerland AG.)

The Tbx6 transcription factor plays multiple roles during gastrulation, somite formation and body axis determination. One of the notable features of the Tbx6 homozygous mutant phenotype is randomization of left/right axis determination. Cilia of the node are morphologically abnormal, leading to the hypothesis that disrupted nodal flow is the cause of the laterality defect. However, Tbx6 is expressed around but not in the node, leading to uncertainty as to the mechanism of this effect. In this study, we have examined the molecular characteristics of the node and the genetic cascade determining left/right axis determination. We found evidence that a leftward nodal flow is generated in Tbx6 homozygous mutants despite the cilia defect, establishing the initial asymmetric gene expression in Dand5 around the node, but that the transduction of the signal from the node to the left lateral plate mesoderm is disrupted due to lack of expression of the Nodal coligand Gdf1 around the node. Gdf1 was shown to be a downstream target of Tbx6 and a Gdf1 transgene partially rescues the laterality defect.

Only few copy number variants at chromosome 19p13.11 have been reported, thus associated clinical information is scarce. Proximal to these copy number losses, we now identified deletions in five unrelated individuals with neurodevelopmental disorders. They presented with psychomotor delay as well as behavioral and sleeping disorders, while complex cardiovascular, skeletal, and various other malformations were more variable. Dysmorphic features were rather unspecific and not considered as a recognizable gestalt. Neither of the analyzed parents carried their offsprings' deletions, indicating de novo occurrence. The deletion sizes ranged between 0.7 and 5.2 Mb, were located between 18 and 24 megabases from the telomere, and contained a variable number of protein-coding genes (n = 25–68). Although not all microdeletions shared a common region, the smallest common overlap of some of the deletions provided interesting insights in the chromosomal region 19p13.11p12. Diligent literature review using OMIM and Pubmed did not identify a satisfying candidate gene for neurodevelopmental disorders. In the literature, a de novo in-frame deletion in MAU2 was considered pathogenic in an individual with Cornelia de Lange syndrome. Therefore, the clinical differential diagnosis of this latter syndrome in one individual and the encompassment of MAU2 in three individuals' deletions suggest clinical and genetic overlap with this specific syndrome. Three of the four here reported individuals with deletion encompassing GDF1 had different congenital heart defects, suggesting that this gene's haploinsufficiency might contribute to the cardiovascular phenotype, however, with reduced penetrance. Our findings indicate an association of microdeletions at 19p13.11/ 19p13.11p12 with neurodevelopmental disorders, variable symptoms, and malformations, and delineate the phenotypic spectrum of deletions within this genomic region. [ABSTRACT FROM AUTHOR]

Growth/differentiation factor 1 ( GDF1) is a secreted glycoprotein of the transforming growth factor-β ( TGF-β) superfamily that mediates cell differentiation events during embryonic development. GDF1 is expressed in several tissues, including the heart. However, the functional role of GDF1 in myocardial infarction ( MI)-induced cardiac remodelling and dysfunction is not known. Here, we performed gain-of-function and loss-of-function studies using cardiac-specific GDF1 transgenic ( TG) and knockout ( KO) mice to determine the role of GDF1 in the pathogenesis of functional and architectural cardiac remodelling after MI, which was induced by surgical left anterior descending coronary artery ligation. Our results demonstrate that overexpression of GDF1 in the heart causes a significant decrease in MI-derived mortality post- MI and leads to attenuated infarct size expansion, left ventricular ( LV) dilatation, and cardiac dysfunction at 1 week and 4 weeks after MI injury. Compared with control animals, cardiomyocyte apoptosis, inflammation, hypertrophy, and interstitial fibrosis were all remarkably reduced in the GDF1- TG mice following MI. In contrast, GDF1 deficiency greatly exacerbated the pathological cardiac remodelling response after infarction. Further analysis of the in vitro and in vivo signalling events indicated that the beneficial role of GDF1 in MI-induced cardiac dysfunction and LV remodelling was associated with the inhibition of non-canonical ( MEK-ERK1/2) and canonical (Smad) signalling cascades. Overall, our data reveal that GDF1 in the heart is a novel mediator that protects against the development of post-infarction cardiac remodelling via negative regulation of the MEK-ERK1/2 and Smad signalling pathways. Thus, GDF1 may serve as a valuable therapeutic target for the treatment of MI. Copyright © 2015 Pathological Society of Great Britain and Ireland. Published by John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

Background: Mutations in the T-box gene Brachyury have well known effects on invagination of the endomesodermal layer during gastrulation, but the gene also plays a role in the determination of left/right axis determination that is less well studied. Previous work has implicated node morphology in this effect. We use the TWis allele of Brachyury to investigate the molecular and morphological effects of the T locus on axis determination in the mouse. Results: Similar to embryos mutant for the T allele, TWis/TWis embryos have a high incidence of ventral and/or reversed heart looping. In addition, heterotaxia between the direction of heart looping and the direction of embryo turning is common. Scanning electron microscopy reveals defects in node morphology including irregularity, smaller size, and a decreased number of cilia, although the cilia appear morphologically normal. Molecular analysis shows a loss of perinodal expression of genes involved in Nodal signaling, namely Cer2, Gdf1, and Nodal itself. There is also loss of Dll1 expression, a key component of the Notch signaling pathway, in the presomitic mesoderm. Conclusions: Morphological abnormalities of the node as well as disruptions of the molecular cascade of left/right axis determination characterize TWis/TWis mutants. Decreased Notch signaling may account for both the morphological defects and the absence of expression of genes in the Nodal signaling pathway. Developmental Dynamics 243:1046-1053, 2014. © 2014 Wiley Periodicals, Inc. [ABSTRACT FROM AUTHOR]

Abstract: Pathological cardiac hypertrophy is a major risk factor for developing heart failure, the leading cause of death in the world. Growth/differentiation factor 1 (GDF1), a transforming growth factor-β family member, is a regulator of cell growth and differentiation in both embryonic and adult tissues. Evidence from human and animal studies suggests that GDF1 may play an important role in cardiac physiology and pathology. However, a critical role for GDF1 in cardiac remodelling has not been investigated. Here, we performed gain-of-function and loss-of-function studies using cardiac-specific GDF1 knockout mice and transgenic mice to determine the role of GDF1 in pathological cardiac hypertrophy, which was induced by aortic banding (AB). The extent of cardiac hypertrophy was evaluated by echocardiographic, hemodynamic, pathological, and molecular analyses. Our results demonstrated that cardiac specific GDF1 overexpression in the heart markedly attenuated cardiac hypertrophy, fibrosis, and cardiac dysfunction, whereas loss of GDF1 in cardiomyocytes exaggerated the pathological cardiac hypertrophy and dysfunction in response to pressure overload. Mechanistically, we revealed that the cardioprotective effect of GDF1 on cardiac remodeling was associated with the inhibition of the MEK–ERK1/2 and Smad signaling cascades. Collectively, our data suggest that GDF1 plays a protective role in cardiac remodeling via the negative regulation of the MEK–ERK1/2 and Smad signaling pathways. [Copyright &y& Elsevier]

Abstract: Objective: Klippel–Feil syndrome is characterized by faulty segmentation of two or more cervical vertebrae and, in its most severe form, consists of massive cervical vertebral fusion, short neck, low posterior hairline, and limitation of head movement. Several cases associating Klippel–Feil syndrome with situs inversus totalis have been reported. In the present study, we describe the clinical features of a novel case of Klippel–Feil syndrome associated with situs inversus totalis and searched for mutations in GDF1, GDF3 and GDF6 genes, which were recently implicated in the development of skeletal and visceral anomalies. Methods: A case of Klippel–Feil syndrome associated with situs inversus totalis underwent a full clinical examination including X-ray of cervical spine and thorax, abdominal ultrasound, and computerized tomography scanning of thorax and abdomen. PCR amplification and automated nucleotide sequencing of coding exons and intron–exon junctions of GDF1, GDF3, and GDF6 genes were performed in genomic DNA. Results: No molecular alterations were found in GDF1, GDF3 and GDF6 genes in this patient. Conclusion: An additional patient associating Klippel–Feil syndrome and situs inversus totalis is reported. Mutations in GDF1, GDF3, and GDF6 genes were excluded as the cause of this unusual clinical association. [Copyright &y& Elsevier]

Conotruncal defects (CTDs) represent 15-20% of all congenital heart defects. Mutations in a number of genes have been associated with CTD in humans and animal models. We investigated the occurrence and the prevalence of GATA4, NKX2.5, ZFPM2/FOG2, GDF1, and ISLET1 gene mutations in a large cohort of individuals with CTD, including tetralogy of Fallot with or without pulmonary atresia (TOF, 178 patients), double outlet right ventricle (DORV, 13 patients), and truncus arteriosus (11 patients). Denaturing high-performance liquid chromatography (DHPLC) analysis followed by bidirectional sequencing disclosed no putative pathogenic mutation in GATA4, ISLET1, and GDF1 genes. Two novel (Ile227Val, Met544Ile) and one previously reported (Glu30Gly) possibly pathogenic missense variants were identified in the ZFPM2/FOG2 gene in 3 sporadic patients of 202 (1.5%) with CTD, including 1 of 178 (0.6%) with TOF and 2 of 13 (15.4%) with DORV. Mutation analysis also detected one known missense change (Arg25Cys) in NKX2.5 gene in two (1.1%) sporadic patients with TOF. These sequence alterations were found to be absent in 500 population-matched controls. In conclusion, the present results (i) indicate and confirm that mutations in the GATA4, GDF1, and ISLET1 genes are not major determinants in the pathogenesis of TOF, (ii) provide supportive evidence of an association between ZFPM2/FOG2 gene and TOF/DORV, and (iii) provide additional examples of the possible contribution of the Arg25Cys change in the NKX2.5 to a small number of TOF cases. [ABSTRACT FROM AUTHOR]

Abstract: The cyclopic and laterality phenotypes in model organisms linked to disturbances in the generation or propagation of Nodal-like signals are potential examples of similar impairments resulting in birth defects in humans. However, the types of gene mutation(s) and their pathogenetic combinations in humans are poorly understood. Here we describe a mutational analysis of the human NODAL gene in a large panel of patients with phenotypes compatible with diminished NODAL ligand function. Significant reductions in the biological activity of NODAL alleles are detected among patients with congenital heart defects (CHD), laterality anomalies (e.g. left–right mis-specification phenotypes), and only rarely holoprosencephaly (HPE). While many of these NODAL variants are typical for family-specific mutations, we also report the presence of alleles with significantly reduced activity among common population variants. We propose that some of these common variants act as modifiers and contribute to the ultimate phenotypic outcome in these patients; furthermore, we draw parallels with strain-specific modifiers in model organisms to bolster this interpretation. [Copyright &y& Elsevier]

Inorganic arsenic, an environmental contaminant, has adverse health outcomes. Our previous studies showed that arsenic causes abnormal cardiac development in zebrafish embryos by downregulating Dvr1/GDF1 expression and that folic acid protects against these effects. However, the mechanism by which arsenic represses Dvr1/GDF1 expression remains unknown. Herein, we demonstrate that specificity protein 1 (Sp1) acts as a transcriptional activator of GDF1. Arsenic treatment downregulated Sp1 at both the mRNA and protein level and its downstream targets GDF1 and SIRT1. Chromatin immunoprecipitation analysis showed that the occupancy of Sp1 on the GDF1 or SIRT1 promoter was significantly reduced in response to arsenite. Further investigation showed that Sp1 overexpression inhibited the arsenic-mediated decrease in GDF1 and SIRT1, while Sp1 knockdown had the opposite effect. We found that expression of the oxidative adaptor p66shc was inversely related to that of SIRT1 and that the binding of SIRT1 to the p66shc promoter was sharply attenuated by arsenite treatment. SIRT1 overexpression attenuated p66shc expression but enhanced GDF1 protein expression, while SIRT1 depletion exerted the opposite effect. Both the antioxidants N-acetylcysteine and folic acid reversed the arsenic-mediated repression of Sp1, GDF1 and SIRT1. Moreover, wild-type p66shc overexpression enhanced the arsenic-mediated repression of Sp1, GDF1 and SIRT1, which was accompanied by an increase in intracellular reactive oxygen species (ROS) levels, while both overexpression of a dominant negative p66shcSer36Ala mutant and deficiency in p66shc reversed these effects. Taken together, our results revealed that arsenic suppresses GDF1 expression via the ROS-dependent downregulation of the Sp1/SIRT1 axis, which forms a negative feedback loop with p66shc to regulate oxidative stress. Our findings reveal a novel molecular mechanism underlying arsenic toxicity and provide new insight into the protective effect of folic acid in arsenic-mediated toxicity. Image 1 • Sp1 transactivates GDF1 expression. • Arsenic suppresses GDF1 by ROS-dependent downregulation of Sp1. • Arsenic inhibits Sp1/SIRT1 pathway that formed a loop with p66shc to regulate oxidative stress. • Folic acid rescues arsenic-mediated repression of Sp1, GDF1 and SIRT1. Arsenic suppresses GDF1 through ROS-dependent downregulation of the Sp1/SIRT1 axis, which forms a negative feedback loop with p66shc to regulate oxidative stress. [ABSTRACT FROM AUTHOR]

GDF1 plays an important role in left-right patterning and genetic mutations in the coding region of GDF1 are associated with congenital heart disease (CHD). However, the genetic variation in the promoter of GDF1 with sporadic CHD and its expression regulation is little known. The association of the genetic variation in GDF1 promoter with CHD was examined in two case-control studies, including 1084 cases and 1198 controls in the first study and 582 cases and 615 controls in the second study. We identified one single nucleotide polymorphism (SNP) rs181317402 and two novel genetic mutations located in the promoter region of GDF1. Analysis of combined samples revealed a significant association in genotype and allele frequencies of rs181317402 T/G polymorphism between CHD cases in overall or ventricular septal defects or Tetralogy of Fallot and the control group. rs181317402 allele G polymorphism was significantly associated with a decreased risk of CHD. Furthermore, luciferase assay, chromatin immunoprecipitation and DNA pulldown assay indicated that Nkx2.5 transactivated the expression of GDF1 by binding to the promoter of GDF1. Luciferase activity assay showed that rs181317402 allele G significantly increased the basal and Nkx2.5-mediated activity of GDF1 promoter, while the two genetic mutations had the opposite effect. rs181317402 TG genotype was associated with significantly increased mRNA level of GDF1 compared with TT genotype in 18 CHD individuals. Our results demonstrate for the first time that Nkx2.5 acts upstream of GDF1 and the genetic variants in GDF1 promoter may confer genetic susceptibility to sporadic CHD potentially by altering its expression., (© 2019 The Author(s). Published by Portland Press Limited on behalf of the Biochemical Society.)

The Tbx6 transcription factor plays multiple roles during gastrulation, somite formation and body axis determination. One of the notable features of the Tbx6 homozygous mutant phenotype is randomization of left/right axis determination. Cilia of the node are morphologically abnormal, leading to the hypothesis that disrupted nodal flow is the cause of the laterality defect. However, Tbx6 is expressed around but not in the node, leading to uncertainty as to the mechanism of this effect. In this study, we have examined the molecular characteristics of the node and the genetic cascade determining left/right axis determination. We found evidence that a leftward nodal flow is generated in Tbx6 homozygous mutants despite the cilia defect, establishing the initial asymmetric gene expression in Dand5 around the node, but that the transduction of the signal from the node to the left lateral plate mesoderm is disrupted due to lack of expression of the Nodal coligand Gdf1 around the node. Gdf1 was shown to be a downstream target of Tbx6 and a Gdf1 transgene partially rescues the laterality defect., Competing Interests: Competing interestsThe authors declare no competing or financial interests., (© 2018. Published by The Company of Biologists Ltd.)

GDF1 (growth/differentiation factor 1), a Vg1-related member of the transforming growth factor-² superfamily, is required for left-right patterning in the mouse, but the precise function of GDF1 has remained largely unknown. In contrast to previous observations, we now show that GDF1 itself is not an effective ligand but rather functions as a coligand for Nodal. GDF1 directly interacts with Nodal and thereby greatly increases its specific activity. Gdf1 expression in the node was found necessary and sufficient for initiation of asymmetric Nodal expression in the lateral plate of mouse embryos. Coexpression of GDF1 with Nodal in frog embryos increased the range of the Nodal signal. Introduction of Nodal alone into the lateral plate of Gdf1 knockout mouse embryos did not induce Lefty1 expression at the midline, whereas introduction of both Nodal and GDF1 did, showing that GDF1 is required for long-range Nodal signaling from the lateral plate to the midline. These results suggest that GDF1 regulates the activity and signaling range of Nodal through direct interaction. [ABSTRACT FROM AUTHOR]

Background: Mutations in the T-box gene Brachyury have well known effects on invagination of the endomesodermal layer during gastrulation, but the gene also plays a role in the determination of left/right axis determination that is less well studied. Previous work has implicated node morphology in this effect. We use the T(Wis) allele of Brachyury to investigate the molecular and morphological effects of the T locus on axis determination in the mouse., Results: Similar to embryos mutant for the T allele, T(Wis) /T(Wis) embryos have a high incidence of ventral and/or reversed heart looping. In addition, heterotaxia between the direction of heart looping and the direction of embryo turning is common. Scanning electron microscopy reveals defects in node morphology including irregularity, smaller size, and a decreased number of cilia, although the cilia appear morphologically normal. Molecular analysis shows a loss of perinodal expression of genes involved in Nodal signaling, namely Cer2, Gdf1, and Nodal itself. There is also loss of Dll1 expression, a key component of the Notch signaling pathway, in the presomitic mesoderm., Conclusions: Morphological abnormalities of the node as well as disruptions of the molecular cascade of left/right axis determination characterize T(Wis) /T(Wis) mutants. Decreased Notch signaling may account for both the morphological defects and the absence of expression of genes in the Nodal signaling pathway., (© 2014 Wiley Periodicals, Inc.)