Search

Background: Drought stress limits significantly the crop productivity. However, plants have evolved various strategies to cope with the drought conditions by adopting complex molecular, biochemical, and physiological mechanisms. Members of the nuclear factor Y (NF-Y) transcription factor (TF) family constitute one of the largest TF classes and are involved in plant responses to abiotic stresses., Results: TaNF-YB2, a NY-YB subfamily gene in T. aestivum, was characterized in this study focusing on its role in mediating plant adaptation to drought stress. Yeast two-hybrid (Y-2 H), biomolecular fluoresence complementation (BiFC), and Co-immunoprecipitation (Co-IP) assays indicated that TaNF-YB2 interacts with the NF-YA member TaNF-YA7 and NF-YC family member TaNF-YC7, which constitutes a heterotrimer TaNF-YB2/TaNF-YA7/TaNF-YC7. The TaNF-YB2 transcripts are induced in roots and aerial tissues upon drought signaling; GUS histochemical staining analysis demonstrated the roles of cis-regulatory elements ABRE and MYB situated in TaNF-YB2 promoter to contribute to target gene response to drought. Transgene analysis on TaNF-YB2 confirmed its functions in regulating drought adaptation via modulating stomata movement, osmolyte biosynthesis, and reactive oxygen species (ROS) homeostasis. TaNF-YB2 possessed the abilities in transcriptionally activating TaP5CS2, the P5CS family gene involving proline biosynthesis and TaSOD1, TaCAT5, and TaPOD5, the genes encoding antioxidant enzymes. Positive correlations were found between yield and the TaNF-YB2 transcripts in a core panel constituting 45 wheat cultivars under drought condition, in which two types of major haplotypes including TaNF-YB2-Hap1 and -Hap2 were included, with the former conferring more TaNF-YB2 transcripts and stronger plant drought tolerance., Conclusions: TaNF-YB2 is transcriptional response to drought stress. It is an essential regulator in mediating plant drought adaptation by modulating the physiological processes associated with stomatal movement, osmolyte biosynthesis, and reactive oxygen species (ROS) homeostasis, depending on its role in transcriptionally regulating stress response genes. Our research deepens the understanding of plant drought stress underlying NF-Y TF family and provides gene resource in efforts for molecular breeding the drought-tolerant cultivars in T. aestivum., (© 2024. The Author(s).)

Atrial fibrillation (AF) represents the most frequent form of sustained cardiac rhythm disturbance, affecting approximately 1% of the general population worldwide, and confers a substantially enhanced risk of cerebral stroke, heart failure, and death. Increasing epidemiological studies have clearly demonstrated a strong genetic basis for AF, and variants in a wide range of genes, including those coding for ion channels, gap junction channels, cardiac structural proteins and transcription factors, have been identified to underlie AF. Nevertheless, the genetic pathogenesis of AF is complex and still far from completely understood. Here, whole-exome sequencing and bioinformatics analyses of a three-generation family with AF were performed, and after filtering variants by multiple metrics, we identified a heterozygous variant in the ISL1 gene (encoding a transcription factor critical for embryonic cardiogenesis and postnatal cardiac remodeling), NM_002202.2: c.481G > T; p.(Glu161*), which was validated by Sanger sequencing and segregated with autosome-dominant AF in the family with complete penetrance. The nonsense variant was absent from 284 unrelated healthy individuals used as controls. Functional assays with a dual-luciferase reporter assay system revealed that the truncating ISL1 protein lost transcriptional activation on the verified target genes MEF2C and NKX2-5. Additionally, the variant nullified the synergistic transactivation between ISL1 and TBX5 as well as GATA4, two other transcription factors that have been implicated in AF. The findings suggest ISL1 as a novel gene contributing to AF, which adds new insight to the genetic mechanisms underpinning AF, implying potential implications for genetic testing and risk stratification of the AF family members., (Copyright © 2020 Elsevier Masson SAS. All rights reserved.)

Occurring in about 1% of all live births, congenital heart defects (CHDs) represent the most frequent type of developmental abnormality and account for remarkably increased infant morbidity and mortality. Aggregating studies demonstrate that genetic components have a key role in the occurrence of CHDs. Nevertheless, due to pronounced genetic heterogeneity, the genetic causes of CHDs remain unclear in most patients. In this research, 114 unrelated patients affected with CHDs and 218 unrelated individuals without CHDs served as controls were recruited. The coding regions and splicing donors/acceptors of the ISL1 gene, which codes for a transcription factor required for proper cardiovascular development, were screened for mutations by sequencing in all study participants. The functional characteristics of an identified ISL1 mutation were delineated with a dual-luciferase reporter assay system. As a result, a new heterozygous ISL1 mutation, NM_002202.2: c.225C>G; p. (Tyr75*), was discovered in an index patient with double outlet right ventricle and ventricular septal defect. Analysis of the proband's family unveiled that the mutation co-segregated with the CHD phenotype. The nonsense mutation was absent in the 436 control chromosomes. Biological analysis showed that the mutant ISL1 protein had no transcriptional activity. Furthermore, the mutation nullified the synergistic activation between ISL1 and TBX20, another CHD-associated transcription factor. This research for the first time links an ISL1 loss-of-function mutation to double outlet right ventricle in humans, which adds insight to the molecular pathogenesis underpinning CHDs, suggesting potential implications for timely personalized management of CHD patients.

Dilated cardiomyopathy (DCM) is the most prevalent cause of non-ischemic cardiac failure and the commonest indication for cardiac transplantation. Compelling evidence highlights the pivotal roles of genetic defects in the occurrence of DCM. Nevertheless, the genetic determinants underpinning DCM remain largely obscure. In this study, the coding regions of ISL1, which encodes a transcription factor critical for embryonic cardiogenesis and postnatal cardiac remodeling, were sequenced in 216 unrelated patients with DCM, and a novel heterozygous ISL1 mutation, NM_002202.2: c.631A>T; p.(Lys211*), was identified in a proband. The mutation, which co-segregated with DCM in the family, was absent in 238 unrelated controls, as well as in the Genome Aggregation and the Exome Aggregation Consortium population databases. Functional analyses unveiled that the mutant ISL1 protein lost transcriptional activity alone or in synergy with TBX20 or GATA4, two other transcription factors associated with DCM. These findings indicate ISL1 as a new gene of DCM.

Congenital heart defect (CHD) is the most common form of birth deformity and is responsible for substantial morbidity and mortality in humans. Increasing evidence has convincingly demonstrated that genetic defects play a pivotal role in the pathogenesis of CHD. However, CHD is a genetically heterogeneous disorder and the genetic basis underpinning CHD in the vast majority of cases remains elusive. This study was sought to identify the pathogenic mutation in the ISL1 gene contributing to CHD. A cohort of 210 unrelated patients with CHD and a total of 256 unrelated healthy individuals used as controls were registered. The coding exons and splicing boundaries of ISL1 were sequenced in all study subjects. The functional effect of an identified ISL1 mutation was evaluated using a dual-luciferase reporter assay system. A novel heterozygous ISL1 mutation, c.409G > T or p.E137X, was identified in an index patient with congenital patent ductus arteriosus and ventricular septal defect. Analysis of the proband's pedigree revealed that the mutation co-segregated with CHD, which was transmitted in the family in an autosomal dominant pattern with complete penetrance. The nonsense mutation was absent in 512 control chromosomes. Functional analysis unveiled that the mutant ISL1 protein failed to transactivate the promoter of MEF2C, alone or in synergy with TBX20. This study firstly implicates ISL1 loss-of-function mutation with CHD in humans, which provides novel insight into the molecular mechanism of CHD, implying potential implications for genetic counseling and individually tailored treatment of CHD patients.

Background: The zinc finger transcription factor CASZ1 plays a key role in cardiac development and postnatal adaptation, and in mice, deletion of the CASZ1 gene leads to dilated cardiomyopathy (DCM). However, in humans whether genetically defective CASZ1 contributes to DCM remains unclear., Methods: The coding exons and splicing junction sites of the CASZ1 gene were sequenced in 138 unrelated patients with idiopathic DCM. The available family members of the index patient harboring an identified CASZ1 mutation and 200 unrelated, ethnically matched healthy individuals used as controls were genotyped for CASZ1. The functional characteristics of the mutant CASZ1 were analyzed in contrast to its wild-type counterpart using a luciferase reporter assay system., 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 CASZ1 as a new gene responsible for human DCM, which provides novel mechanistic insight and potential therapeutic target for CASZ1-associated DCM, implying potential implications in improved prophylactic and therapeutic strategies for DCM, the most common type of primary myocardial 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., (Copyright © 2016. Published by Elsevier B.V.)

Congenital heart disease (CHD) is the most prevalent developmental abnormality in humans and is the most common non-infectious cause of infant morbidity and mortality. Increasing evidence demonstrates that genetic defects are involved in the pathogenesis of CHD. However, CHD is genetically heterogeneous, and the genetic determinants underpinning CHD in most patients remain unknown. In this study, the whole coding region of the PITX2 gene (isoform c) was sequenced in 185 unrelated patients with CHD. The available relatives of a mutation carrier and 300 unrelated healthy individuals used as controls were also genotyped for PITX2. The functional characteristics of the mutation were delineated by using a dual-luciferase reporter assay system. As a result, a novel heterozygous PITX2 mutation, p.Q102L, was identified in a patient with tetralogy of Fallot (TOF). Genetic analysis of the index patient's pedigree showed that the mutation co-segregated with TOF. The mutation was absent in 600 reference chromosomes. Biochemical analysis revealed that the Q102L-mutant PITX2 is associated with significantly reduced transcriptional activity compared with its wild-type counterpart. Furthermore, the mutation markedly decreased the synergistic activation between PITX2 and NKX2-5. This study firstly associates PITX2 loss-of-function mutation with increased susceptibility to TOF, providing novel insight into the molecular mechanism of CHD., (Copyright © 2015 Elsevier B.V. All rights reserved.)

Congenital heart disease (CHD) is the most common birth defect and is the most prevalent non-infectious cause of infant death. Aggregating evidence demonstrates that genetic defects are involved in the pathogenesis of CHD. However, CHD is genetically heterogeneous and the genetic determinants for CHD in an overwhelming majority of patients remain unknown. In this study, the coding regions and splice junctions of the NKX2.6 gene, which encodes a homeodomain transcription factor crucial for cardiovascular development, were sequenced in 210 unrelated CHD patients. As a result, a novel heterozygous NKX2.6 mutation, p.K152Q, was identified in an index patient with ventricular septal defect (VSD). Genetic analysis of the proband's available family members showed that the mutation cosegregated with VSD transmitted as an autosomal dominant trait with complete penetrance. The missense mutation was absent in 400 control chromosomes and the altered amino acid was completely conserved evolutionarily across species. Due to unknown transcriptional targets of NKX2.6, the functional characteristics of the identified mutation at transcriptional activity were analyzed by using NKX2.5 as a surrogate. Alignment between human NKX2.6 and NKX2.5 proteins displayed that K152Q-mutant NKX2.6 was equivalent to K158Q-mutant NKX2.5, and introduction of K158Q into NKX2.5 significantly reduced its transcriptional activating function when compared with its wild-type counterpart. This study firstly links NKX2.6 loss-of-function mutation with increased susceptibility to isolated VSD, providing novel insight into the molecular mechanism underpinning VSD and contributing to the development of new preventive and therapeutic strategies for this common form of CHD.

Dilated cardiomyopathy (DCM) is the most prevalent type of primary myocardial disease, which is the third most common cause of heart failure and the most frequent reason for heart transplantation. Aggregating evidence demonstrates that genetic risk factors are involved in the pathogenesis of idiopathic DCM. Nevertheless, DCM is of remarkable genetic heterogeneity and the genetic defects underpinning DCM in an overwhelming majority of patients remain unknown. In the present study, the whole coding exons and splice junction sites of the NKX2-5 gene, which encodes a homeodomain transcription factor crucial for cardiac development and structural remodeling, were sequenced in 130 unrelated patients with idiopathic DCM. The available relatives of the index patient harboring an identified mutation and 200 unrelated ethnically matched healthy individuals used as controls were genotyped for the NKX2-5 gene. The functional effect of the mutant NKX2-5 was characterized in contrast to its wild-type counterpart using a dual-luciferase reporter assay system. As a result, a novel heterozygous NKX2-5 mutation, p.S146W, was identified in a family with DCM inherited as an autosomal dominant trait, which co-segregated with DCM in the family with complete penetrance. Notably, the mutation carriers also had arrhythmias, such as paroxysmal atrial fibrillation and atrioventricular block. The missense mutation was absent in 400 reference chromosomes and the altered amino acid was completely conserved evolutionarily among species. Functional analysis revealed that the NKX2-5 mutant was associated with a significantly reduced transcriptional activity. The findings expand the mutational spectrum of NKX2-5 linked to DCM and provide novel insight into the molecular mechanisms underlying DCM, contributing to the antenatal prophylaxis and allele-specific management of DCM.

Bicuspid aortic valve (BAV) is the most common form of congenital cardiovascular defect in humans and is associated with substantial morbidity and mortality. Emerging evidence demonstrates that genetic risk factors play an important role in the pathogenesis of BAV. However, BAV is a genetically heterogenous disorder, and the genetic defects underpinning BAV in most patients remain to be identified. In the present study, the coding exons and flanking introns of the NKX2.5 gene, which encodes a homeodomain-containing transcription factor essential for the normal development of the aortic valve, were sequenced in 142 unrelated patients with BAV. The available relatives of the mutation carrier and 200 unrelated healthy subjects used as controls were also genotyped for NKX2.5. The functional characteristics of the mutation were delineated by using a dual-luciferase reporter assay system. As a result, a novel heterozygous NKX2.5 mutation, p.K192X, was identified in a family with BAV transmitted in an autosomal dominant pattern. The nonsense mutation was absent in 400 control chromosomes. Functional analyses revealed that the mutant NKX2.5 had no transcriptional activity compared with its wild-type counterpart. Furthermore, the mutation abolished the synergistic transcriptional activation between NKX2.5 and GATA5, another transcription factor crucial for the aortic valvular morphogenesis. In conclusion, this study is the first to link an NKX2.5 loss-of-function mutation to enhanced susceptibility to human BAV, providing novel insight into the molecular mechanism of BAV and suggesting potential implications for genetic counseling and clinical care of families presenting with BAV., (Copyright © 2014 Elsevier Inc. All rights reserved.)

Objective: This study aimed to identify novel PITX2c mutations responsible for idiopathic atrial fibrillation., Methods: A cohort of 210 unrelated patients with idiopathic atrial fibrillation and 200 unrelated, ethnically matched healthy individuals used as controls were recruited. The whole coding exons and splice junctions of the PITX2c gene, which encodes a paired-like homeobox transcription factor required for normal cardiovascular morphogenesis, were sequenced in 210 patients and 200 control subjects. The causative potentials of the identified mutations were automatically predicted by MutationTaster and PolyPhen-2. The functional characteristics of the PITX2c mutations were explored using a dual-luciferase reporter assay system., Results: Two novel heterozygous PITX2c mutations (p.Q105L and p.R122C) were identified in 2 of the 210 unrelated patients with idiopathic atrial fibrillation. These missense mutations were absent in the 400 control chromosomes and were both predicted to be pathogenic. Multiple alignments of PITX2c protein sequences across various species showed that the altered amino acids were highly evolutionarily conserved. A functional analysis demonstrated that the mutant PITX2c proteins were both associated with significantly reduced transcriptional activity compared with their wild-type counterparts., Conclusion: The findings of this study associate PITX2c loss-of-function mutations with atrial fibrillation, supporting the hypothesis that dysfunctional PITX2c confers enhanced susceptibility to atrial fibrillation and suggesting potential implications for early prophylaxis and allele-specific therapy for this common arrhythmia.

Congenital heart disease (CHD) is the most common form of developmental anomaly and is the leading non-infectious cause of infant mortality. A growing body of evidence demonstrates that genetic risk factors are involved in the pathogenesis of CHD. However, CHD is a genetically heterogeneous disease and the genetic determinants for CHD in most patients remain unclear. In the present study, the entire coding region and splice junction sites of the PITX2c gene, which encodes a homeobox transcription factor crucial for normal cardiovascular genesis, was sequenced in 150 unrelated patients with various CHDs. The 200 unrelated control individuals were subsequently genotyped. The functional characteristics of the mutations were explored using a dual-luciferase reporter assay system. As a result, two novel heterozygous PITX2c mutations, p.H98Q and p.M119T, were identified in 2 unrelated patients with atrial septal defects, respectively. The variations were absent in 400 control chromosomes and the affected amino acids were completely conserved evolutionarily. The two variants were both predicted to be disease-causing by MutationTaster and PolyPhen-2, and the functional analysis revealed that the PITX2c mutants were consistently associated with significantly reduced transcriptional activity compared with their wild-type counterpart. These findings firstly link PITX2c loss-of-function mutations to atrial septal defects in humans, which provide novel insight into the molecular mechanism responsible for CHD, suggesting potential implications for the early prophylaxis and allele-specific treatment of CHD.

Objective: The aim of this study was to evaluate the prevalence and spectrum of Nkx2.5 mutations associated with idiopathic atrial fibrillation (AF)., Methods: A cohort of 136 unrelated patients with idiopathic atrial fibrillation and 200 unrelated, ethnically matched healthy controls were enrolled. The coding exons and splice junctions of the Nkx2.5 gene were sequenced in 136 atrial fibrillation patients, and the available relatives of mutation carriers and 200 controls were subsequently genotyped for the identified mutations. The functional characteristics of the mutated Nkx2.5 gene were analyzed using a dual-luciferase reporter assay system., Results: Two novel heterozygous Nkx2.5 mutations (p.N19D and p.F186S) were identified in 2 of the 136 unrelated atrial fibrillation cases, with a mutational prevalence of approximately 1.47%. These missense mutations co-segregated with atrial fibrillation in the families and were absent in the 400 control chromosomes. Notably, 2 mutation carriers also had congenital atrial septal defects and atrioventricular block. Multiple alignments of the Nkx2.5 protein sequences across various species revealed that the altered amino acids were completely conserved evolutionarily. Functional analysis demonstrated that the mutant Nkx2.5 proteins were associated with significantly reduced transcriptional activity compared to their wild-type counterpart., Conclusion: These findings associate the Nkx2.5 loss-of-function mutation with atrial fibrillation and atrioventricular block and provide novel insights into the molecular mechanism involved in the pathogenesis of atrial fibrillation. These results also have potential implications for early prophylaxis and allele-specific therapy of this common arrhythmia.

Atrial fibrillation (AF) represents the most common form of sustained cardiac arrhythmia and accounts for substantial morbidity and mortality. Increasing evidence demonstrates that abnormal cardiovascular development is involved in the pathogenesis of AF. In this study, the coding exons and splice sites of the NKX2.5 gene, which encodes a homeodomain-containing transcription factor pivotal for normal cardiovascular morphogenesis, were sequenced in 110 unrelated index patients with familial AF. The available relatives of the mutation carrier and 200 unrelated ethnically-matched healthy individuals serving as controls were subsequently genotyped. The disease-causing potential of the identified NKX2.5 variation was predicted by MutationTaster. The functional characteristics of the mutant NKX2.5 protein were analyzed using a dual-luciferase reporter assay system. As a result, a novel heterozygous NKX2.5 mutation, p.F145S, was identified in a family with AF transmitted as an autosomal dominant trait, which co-segregated with AF in the family with complete penetrance. The detected substitution, which altered the amino acid completely conserved evolutionarily across species, was absent in 400 control chromosomes and was automatically predicted to be causative. Functional analysis demonstrated that the NKX2.5 mutant was associated with significantly decreased transcriptional activity compared with its wild-type counterpart. To the best of our knowledge, this is the first report on the association of the NKX2.5 loss-of-function mutation with increased susceptibility to familial AF. The findings of the present study provide novel insights into the molecular mechanism underlying AF, suggesting the potential implications for the early prophylaxis and allele-specific therapy of AF.

Dilated cardiomyopathy (DCM) represents the most frequent form of cardiomyopathy, leading to heart failure, cardiac arrhythmias and death. Accumulating evidence convincingly demonstrates the crucial role of genetic defects in the pathogenesis of DCM, and over 100 culprit genes have been implicated with DCM. However, DCM is of substantial genetic heterogeneity, and the genetic determinants underpinning DCM remain largely elusive. Whole-exome sequencing and bioinformatical analyses were implemented in a consanguineous Chinese family with DCM. A total of 380 clinically annotated control individuals and 166 more DCM index cases then underwent Sanger sequencing analysis for the identified genetic variation. The functional characteristics of the variant were delineated by utilizing a dual-luciferase assay system. A heterozygous variation in the MEF2A gene (encoding myocyte enhancer factor 2A, a transcription factor pivotal for embryonic cardiogenesis and postnatal cardiac adaptation), NM_001365204.1: c.718G>T; p. (Gly240*), was identified, and verified by Sanger sequencing to segregate with autosome-dominant DCM in the family with complete penetrance. The nonsense variation was neither detected in 760 control chromosomes nor found in 166 more DCM probands. Functional analyses revealed that the variant lost transactivation on the validated target genes MYH6 and FHL2, both causally linked to DCM. Furthermore, the variation nullified the synergistic activation between MEF2A and GATA4, another key transcription factor involved in DCM. The findings firstly indicate that MEF2A loss-of-function variation predisposes to DCM in humans, providing novel insight into the molecular mechanisms of DCM and suggesting potential implications for genetic testing and prognostic evaluation of DCM patients. [ABSTRACT FROM AUTHOR]

Tetralogy of Fallot (TOF) is the most prevalent cyanotic congenital heart pathology and causes infant morbidity and mortality worldwide. GATA-binding protein 4 (GATA4) serves as a pivotal transcriptional factor for embryonic cardiogenesis and germline GATA4 mutations are causally linked to TOF. However, the effects of somatic GATA4 mutations on the pathogenesis of TOF remain to be ascertained. In the present study, sequencing assay of GATA4 was performed utilizing genomic DNA derived from resected heart tissue specimens as well as matched peripheral blood specimens of 62 patients with non-familial TOF who underwent surgical treatment for TOF. Sequencing of GATA4 was also performed using the heart tissue specimens as well as matched peripheral venous blood samples of 68 sporadic cases who underwent heart valve displacement because of rheumatic heart disorder and the peripheral venous whole blood samples of 216 healthy subjects. The function of the mutant was explored by dual-luciferase activity analysis. Consequently, a new GATA4 mutation, NM_002052.5:c.708T>G;p.(Tyr236*), was found in the heart tissue of one patient with TOF. No mutation was detected in the heart tissue of the 68 cases suffering from rheumatic heart disorder or in the venous blood samples of all 346 individuals. GATA4 mutant failed to transactivate its target gene, myosin heavy chain 6. Additionally, this mutation nullified the synergistic transactivation between GATA4 and T-box transcription factor 5 or NK2 homeobox 5, two genes causative for TOF. Somatic GATA4 mutation predisposes TOF, highlighting the significant contribution of somatic variations to the molecular pathogenesis underpinning TOF. [ABSTRACT FROM AUTHOR]

Background: The zinc finger transcription factor CASZ1 plays a key role in cardiac development and postnatal adaptation, and in mice, deletion of the CASZ1 gene leads to dilated cardiomyopathy (DCM). However, in humans whether genetically defective CASZ1 contributes to DCM remains unclear. Methods: The coding exons and splicing junction sites of the CASZ1 gene were sequenced in 138 unrelated patients with idiopathic DCM. The available family members of the index patient harboring an identified CASZ1 mutation and 200 unrelated, ethnically matched healthy individuals used as controls were genotyped for CASZ1. The functional characteristics of the mutant CASZ1 were analyzed in contrast to its wild-type counterpart using a luciferase reporter assay system. 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 CASZ1 as a new gene responsible for human DCM, which provides novel mechanistic insight and potential therapeutic target for CASZ1-associated DCM, implying potential implications in improved prophylactic and therapeutic strategies for DCM, the most common type of primary myocardial disease. [ABSTRACT FROM AUTHOR]

Congenital atrial septal defect (ASD) and progressive atriventricular block (AVB) are the two most common phenotypes linked to NK2 homeobox 5 (NKX2.5) mutations in animals and humans. However, the prevalence and spectrum of NKX2.5 mutation in patients with ASD and AVB remain to be elucidated. In the present study, the coding exons and flanking introns of the NKX2.5 gene, which encodes a homeobox-containing transcription factor essential for development of the heart, were sequenced in a cohort of 62 unrelated patients with ASD and AVB, and subsequently in a mutation carrier's available family members. As controls, 300 unrelated, ethnically-matched healthy individuals were recruited, who were also genotyped for NKX2.5. The functional consequence of the mutant NKX2.5 was evaluated in contrast to its wild-type counterpart using a dual-luciferase reporter assay system. As a result, a novel heterozygous NKX2.5 mutation, p.Q181X, was identified in an index patient with ASD and AVB, with a prevalence of ~1.61%. Genetic analysis of the proband's pedigree revealed that the mutation co-segregated with ASD and AVB with complete penetrance. The nonsense mutation, which eliminated partial homeobox and the carboxyl terminus, was absent in the 600 control chromosomes. Functional evaluation showed that the NKX2.5 mutant had no transcriptional activity. Furthermore, the mutation disrupted the synergistic activation between NKX2.5 and GATA binding protein 4, another cardiac core transcription factor associated with ASD. The results of the present study expand the spectrum of NKX2.5 mutations linked to ASD and AVB, and indicated that NKX2.5 loss-of-function mutations are an uncommon cause of ASD and AVB in humans. [ABSTRACT FROM AUTHOR]

Congenital heart disease (CHD) represents the most frequent developmental deformity in human beings and accounts for substantial morbidity and mortality worldwide. Accumulating investigations underscore the strong inherited basis of CHD, and pathogenic variations in >100 genes have been related to CHD. Nevertheless, the heritable defects underpinning CHD remain elusive in most cases, mainly because of the pronounced genetic heterogeneity. In this investigation, a four-generation family with CHD was recruited and clinically investigated. Via whole-exome sequencing and Sanger sequencing assays in selected family members, a heterozygous variation in the SMAD4 gene (coding for a transcription factor essential for cardiovascular morphogenesis), NM_005359.6: c.285T > A; p.(Tyr95*), was identified to be in co-segregation with autosomal-dominant CHD in the entire family. The truncating variation was not observed in 460 unrelated non-CHD volunteers employed as control subjects. Functional exploration by dual-reporter gene analysis demonstrated that Tyr95*-mutant SMAD4 lost transactivation of its two key downstream target genes NKX2.5 and ID2 , which were both implicated with CHD. Additionally, the variation nullified the synergistic transcriptional activation between SMAD4 and GATA4, another transcription factor involved in CHD. These data strongly indicate SMAD4 may be associated with CHD and shed more light on the molecular pathogenesis underlying CHD, implying potential implications for antenatal precise prevention and prognostic risk stratification of the patients affected with CHD. [ABSTRACT FROM AUTHOR]

Background: The basic helix-loop-helix transcription factor HAND1 is essential for cardiac development and structural remodeling, and mutations in HAND1 have been causally linked to various congenital heart diseases. However, whether genetically compromised HAND1 predisposes to dilated cardiomyopathy (DCM) in humans remains unknown. Methods: The whole coding region and splicing junctions of the HAND1 gene were sequenced in 140 unrelated patients with idiopathic DCM. The available family members of the index patient carrying an identified mutation and 260 unrelated ethnically matched healthy individuals used as controls were genotyped for HAND1. The functional effect of the mutant HAND1 was characterized in contrast to its wild-type counterpart by using a dual-luciferase reporter assay system. Results: A novel heterozygous HAND1 mutation, p.R105X, was identified in a family with DCM transmitted as an autosomal dominant trait, which co-segregated with DCM in the family with complete penetrance. The nonsense mutation was absent in 520 control chromosomes. Functional analyses unveiled that the mutant HAND1 had no transcriptional activity. Furthermore, the mutation abolished the synergistic activation between HAND1 and GATA4, another crucial cardiac transcription factors that has been associated with various congenital cardiovascular malformations and DCM. Conclusions: This study firstly reports the association of HAND1 loss-of-function mutation with increased susceptibility to DCM in humans, which provides novel insight into the molecular mechanisms underpinning DCM. [ABSTRACT FROM AUTHOR]

Aims The homeobox transcription factor, Iroquois protein 5 (Irx5), plays an essential role in the generation of region-selective expression of Kv4.2 gene across the left ventricular wall of rodent hearts. Here, we analyse molecular mechanisms underlying the Irx5-induced regulation of the rat Kv4.2 promoter. Methods and results The mRNA levels for Irx members in various heart regions were assessed by RT–PCR. A luciferase reporter gene with the rat Kv4.2 promoter was used to test the effects of Irx members on channel promoter activity. Irx3 and Irx5 mRNAs were differentially distributed across the left ventricular wall, whereas Irx4 message was equally abundant in various ventricular regions. Irx5, but not Irx3 or Irx4, increased Kv4.2 promoter activity in 10T1/2 fibroblasts, whereas the transcription factor decreased promoter activity in neonatal ventricular myocytes. These effects were mediated by the C-terminal portion of Irx5. Irx4 appeared to inhibit the Irx5-induced increase in channel promoter activity in 10T1/2 cells. The N-terminal region of Irx4 was necessary and sufficient for this inhibition. Furthermore, when endogenous Irx4 expression was suppressed with siRNA, Irx5 increased channel promoter activity in neonatal myocytes. Conclusion These results indicate that Irx5 possesses the ability to activate the Kv4.2 promoter. The abundant Irx4 expression throughout the rat ventricle may play a role in the inverse relationship between Irx5 and Kv4.2 levels across the left ventricular wall. [ABSTRACT FROM AUTHOR]

As two members of the basic helix-loop-helix family of transcription factors, HAND1 and HAND2 are both required for the embryonic cardiogenesis and postnatal ventricular structural remodeling. Recently a HAND1 mutation has been reported to cause dilated cardiomyopathy (DCM). However, the association of a HAND2 mutation with DCM is still to be ascertained. In this research, t he coding regions and splicing junction sites of the HAND2 gene were sequenced in 206 unrelated patients affected with idiopathic DCM, and a new heterozygous HAND2 mutation, NM_021973.2: c.199G > T; p.(Glu67*), was discovered in an index patient with DCM. The nonsense mutation was absent in 300 unrelated, ethnically-matched healthy persons. Genetic scan of the mutation carrier's family members revealed that the genetic mutation co-segregated with DCM, which was transmitted in an autosomal dominant fashion, with complete penetrance. Functional deciphers unveiled that the mutant HAND2 protein had no transcriptional activity. In addition, the mutation abrogated the synergistic transcriptional activation between HAND2 and GATA4 or between HAND2 and NKX2.5, two other cardiac transcription factors that have been implicated in DCM. These research findings firstly suggest HAND2 as a novel gene predisposing to DCM in humans, which adds novel insight to the molecular pathogenesis of DCM, implying potential implications in the design of personized preventive and therapeutic strategies against DCM. [ABSTRACT FROM AUTHOR]

Congenital heart defect (CHD) is the most common type of birth defect in humans and a leading cause of infant morbidity and mortality. Previous studies have demonstrated that genetic defects play a pivotal role in the pathogenesis of CHD. However, the genetic basis of CHD remains poorly understood due to substantial genetic heterogeneity. In this study, the coding exons and splicing boundaries of the NR2F2 gene, which encodes a pleiotropic transcription factor required for normal cardiovascular development, were sequenced in 168 unrelated patients with CHD, and a novel mutation (c.247G > T, equivalent to p.G83X) was detected in a patient with double outlet right ventricle as well as ventricular septal defect. Genetic scanning of the mutation carrier's relatives available showed that the mutation was present in all affected family members but absent in unaffected family members. Analysis of the index patient's pedigree displayed that the mutation co-segregated with CHD, which was transmitted as an autosomal dominant trait with complete penetrance. The nonsense mutation was absent in 230 unrelated, ethnically-matched healthy individuals used as controls. Functional deciphers by using a dual-luciferase reporter assay system revealed that the mutant NR2F2 protein had no transcriptional activity as compared with its wild-type counterpart. Furthermore, the mutation abrogated the synergistic transcriptional activation between NR2F2 and GATA4, another core cardiac transcription factor associated with CHD. This study firstly associates NR2F2 loss-of-function mutation with an increased susceptibility to double outlet right ventricle in humans, which provides further significant insight into the molecular mechanisms underpinning CHD, suggesting potential implications for genetic counseling of CHD families and personalized treatment of CHD patients. [ABSTRACT FROM AUTHOR]