Abstract 13269: Reduced Expression of scaRNAs Disrupts Spliceosome Function and Heart Development in Zebrafish and Infants with Tetralogy of Fallot

Circulation ◽  
2014 ◽  
Vol 130 (suppl_2) ◽  
Author(s):  
Douglas C Bittel ◽  
Prakash Patil ◽  
Tamayo Uechi ◽  
Nataliya Kibiryeva ◽  
Jennifer Marshall ◽  
...  

The splicing of messenger RNA plays a fundamental role in regulating vertebrate development and differentiation. Although it is well established that alternative splicing (AS) plays an important role in regulating mammalian heart development, a clear link between misregulated splicing and congenital heart defects has not been shown. We recently reported that more than 50% of genes associated with heart development had significant changes in splice forms in the right ventricle of infants with tetralogy of Fallot (TOF; 14M/7F; all less than 1 yr old). Moreover, there was a significant decrease (30-50%, p<0.05) in the level of 12 scaRNAs. scaRNAs are members of the large family of noncoding small RNAs that are responsible for biochemical modification of specific nucleotides in spliceosomal and ribosomal RNAs. These 12 scaRNAs target two spliceosomal RNAs, U2 and U6. We used primary cells derived from the RV of infants with TOF to show a direct link between scaRNA levels and splice isoforms of several key genes regulating human heart development (e.g., GATA4, NOTCH2, DAAM1, DICER1, MBNL1 and 2). In addition, using available RNA-Seq data, we provide evidence that during zebrafish development, there are dynamic oscillations in scaRNAs and splice isoforms of genes that regulate heart development. We knocked down the expression of two scaRNAs; ACA35 (Scarna1) and U94 (Snord94), in zebrafish and saw a corresponding disruption of heart development. Importantly, there was an accompanying alteration in the ratios of splice isoforms of key cardiac regulatory genes. Based on these combined results, we propose that scaRNAs directly regulate the proficiency of the spliceosome by controlling spliceosomal RNA maturation. This in turn contributes to splice isoform dynamic equilibrium and ultimately heart development. These results are consistent with a failure of normal temporal and spatial splicing patterns during early embryonic development, leading to a breakdown in communication between the first and second heart fields, resulting in conotruncal misalignment and TOF. Our findings represent a new paradigm for understanding congenital cardiac malformations.

Author(s):  
Huseyin Enes Salman ◽  
Maha Alser ◽  
Akshay Shekhar ◽  
Russell A. Gould ◽  
Fatiha M. Benslimane ◽  
...  

AbstractCongenital heart defects (CHDs) are abnormalities in the heart structure present at birth. One important condition is hypoplastic left heart syndrome (HLHS) where severely underdeveloped left ventricle (LV) cannot support systemic circulation. HLHS usually initiates as localized tissue malformations with no underlying genetic cause, suggesting that disturbed hemodynamics contribute to the embryonic development of these defects. Left atrial ligation (LAL) is a surgical procedure on embryonic chick resulting in a phenotype resembling clinical HLHS. In this study, we investigated disturbed hemodynamics and deteriorated cardiac growth following LAL to investigate possible mechanobiological mechanisms for the embryonic development of HLHS. We integrated techniques such as echocardiography, micro-CT and computational fluid dynamics (CFD) for these analyses. Specifically, LAL procedure causes an immediate flow disturbance over atrioventricular (AV) cushions. At later stages after the heart septation, it causes hemodynamic disturbances in LV. As a consequence of the LAL procedure, the left-AV canal and LV volume decrease in size, and in the opposite way, the right-AV canal and right ventricle volume increase. According to our CFD analysis, LAL results in an immediate decrease in the left AV canal WSS levels for 3.5-day (HH21) pre-septated hearts. For 7-day post-septated hearts (HH30), LAL leads to further reduction in WSS levels in the left AV canal, and relatively increased WSS levels in the right AV canal. This study demonstrates the critical importance of the disturbed hemodynamics during the heart valve and ventricle development.


2013 ◽  
Vol 2013 ◽  
pp. 1-11 ◽  
Author(s):  
Kersti K. Linask

Extrapolating from animal studies to human pregnancy, our studies showed that folate (FA) deficiency as well as one-time exposure to environmental factors in the first two to three weeks of human gestation can result in severe congenital heart defects (CHDs). Considering that approximately 49% of pregnancies are unplanned, this period of pregnancy can be considered high-risk for cardiac, as well as for neural, birth defects, as the woman usually is not aware of her pregnancy and may not yet be taking precautionary actions to protect the developing embryo. Using avian and mouse vertebrate models, we demonstrated that FA supplementation prevents CHD induced by alcohol, lithium, or elevation of the metabolite homocysteine, a marker for FA deficiency. All three factors affected the important Wnt signaling pathway by suppressing Wnt-mediated gene expression in the heart fields, resulting in a delay of cardiomyocyte migration, cardiomyogenesis, and CHD. Optimal protection of cardiogenesis was observed to occur with FA supplementation provided upon morning after conception and at higher doses than the presently available in prenatal vitamin supplementation. Our studies demonstrate pathways and cell processes that are involved with protection of one-carbon metabolism during heart development.


Author(s):  
Carmen Lopez-Sanchez ◽  
Virginio Garcia-Lopez ◽  
Gary C. Schoenwolf ◽  
Virginio Garcia-Martinez

The origin and migration of cardiovascular progenitors have been identified using multiple cell fate mapping techniques monitoring marked epiblast cells through time at carefully defined stages of early gastrulation. These studies have revealed that ordered groups of cells from the epiblast move into the anterior region of the primitive streak, and then migrate anterior laterally to define the first heart field in the mesodermal layer. Subsequently, the right and left components of the first heart field fuse into a single straight heart at the embryonic midline. Additional cells derived from the second heart field are added to the cardiac tube and contribute to further heart development. Heterotopic and heterochronic transplantation studies have revealed that cardiac precursor cells are plastic and do not form a specific subpopulation of the cardiac mesoderm. Specification of the heart fields occurs after ingression of precardiac cells through the primitive streak.


2021 ◽  
Vol 47 (1) ◽  
Author(s):  
Sumbal Sarwar ◽  
Farah Ehsan ◽  
Shabana ◽  
Amna Tahir ◽  
Mahrukh Jamil ◽  
...  

Abstract Background Ventricular septal defects (VSDs) are malformations in the septum separating the heart’s ventricles. VSDs may present as a single anomaly (isolated/nonsyndromic VSD) or as part of a group of phenotypes (syndromic VSD). The exact location of the defect is crucial in linking the defect to the underlying genetic cause. The number of children visiting cardiac surgery units is constantly increasing. However, there are no representative data available on the genetics of VSDs in Pakistani children. Methods Two hundred forty-two subjects (121 VSD children and 121 healthy controls) were recruited from pediatric cardiac units of Lahore. The clinical and demographic data of the subjects were collected. A total of four SNPs, one each from MTRR, GATA4, VEGF, and ISL1 genes were genotyped by PCR-RFLP. Results The results showed that the minor allele (T) frequency (MAFs) for the MTRR gene variant rs1532268 (c.524C > T) was 0.20 and 0.41 in the controls and the cases, respectively, with the genotype frequencies 3, 35, 62% in the controls and 12, 59 and 29% in the cases for TT, CT, CC genotypes, respectively (allelic OR: 5.73, CI: 3.82–8.61, p-value: 5.11 × 10− 7). For the GATA4 variant rs104894073 (c.886G > A), the MAF for the controls and the cases was 0.16 and 0.37, respectively, the frequencies of AA, GA and GG genotypes were 2, 28, and 70% in the controls and 5, 64 and 31% of the cases (allelic OR: 3.08, CI: 2.00–4.74, p-value: 8.36 × 10− 8). The rs699947 (c.-2578C > A) of VEGF gene showed MAF 0.36 and 0.53 for the controls and cases, respectively, with the genotype frequencies 13, 42, and 45% in the controls and 22, 15, and 63% in the cases for the AA, CA, CC (allelic OR: 2.03, CI: 1.41–2.92, p-value: 0.0001). The ISL1 gene variant rs6867206 (g.51356860 T > C), the MAFs were 0.26 and 0.31 in the controls and cases, respectively. The genotype frequencies were 48, 52, 0% in the controls and 39, 61, 0% in the cases for TT, TC, CC genotypes (allelic OR: 0.27, CI: 0.85–1.89, p-value: 0.227). The MTRR, GATA4 and VEGF variants showed association while ISL1 variant did not appear to be associated with the VSD in the recruited cohort. Conclusion This first report in Pakistani children demonstrates that single nucleotide polymorphisms in genes encoding transcription factors, signaling molecules and structural heart genes involved in fetal heart development are associated with developmental heart defects., however further work is needed to validate the results of the current investigation.


2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Xin Li ◽  
Jin Zhu ◽  
Jun An ◽  
Yuqing Wang ◽  
Yili Wu ◽  
...  

AbstractCongenital Heart Defects (CHDs) are associated with different patterns of malnutrition and growth retardation, which may vary worldwide and need to be evaluated according to local conditions. Although tetralogy of Fallot (TOF) is one of the first described CHDs, the etiology outcomes in growth and development of TOF in early age child is still unclear in most cases. This study was designed to investigate the growth retardation status of Chinese pediatric TOF patients under 5 years old. The body height, body weight and body mass index (BMI) of 262 pediatric patients (138 boys and 124 girls) who underwent corrective surgery for TOF between 2014 and 2018 were measured using conventional methods. The average body height, body weight and BMI of the patients were significantly lower than WHO Child Growth Standards, while the most affected was body height. Meanwhile, higher stunting frequency and greater deterioration of both the body height and weight happened in elder age (aged 13–60 months) rather than in infant stage (aged 0–12 months) among these patients. Our results confirmed that intervention should be given at early age to prevent the growth retardation of TOF patients getting severer.


2021 ◽  
pp. 1-2
Author(s):  
Niall Linnane ◽  
Andrew Green ◽  
Colin J. McMahon

Abstract 16p12.2 microdeletion has been associated with congenital heart defects and developmental delay. In this case, we describe the rare association between tetralogy of Fallot with an absent pulmonary valve a right-sided aortic arch and a retro-aortic innominate vein associated with a 16p12.2 microdeletion and epilepsy.


Animals ◽  
2021 ◽  
Vol 11 (2) ◽  
pp. 318
Author(s):  
Domenico Caivano ◽  
Maria Chiara Marchesi ◽  
Piero Boni ◽  
Noemi Venanzi ◽  
Giovanni Angeli ◽  
...  

Congenital heart defects have been occasionally reported in cattle and ventricular septal defect represents the most frequently encountered anomaly. The double-outlet right ventricle is a rare congenital ventriculoarterial malformation reported only in certain cattle breeds. We describe this rare and complex congenital cardiac malformation observed in a 10-day-old male Chianina calf. Clinical examination showed tachycardia, tachypnea, jugular pulses, cyanotic mucous membranes and a right apical systolic murmur. Transthoracic echocardiography revealed severe dilation of the right-sided cardiac chambers with a markedly hypoplastic left ventricle. Both aorta and pulmonary artery leaving the right ventricle in parallel alignment with the tricuspid valve were suggestive of a dual-outlet right ventricle. Interventricular and interatrial septal defects were also visualized. Post-mortem examination confirmed the echocardiographic findings. To the authors’ knowledge, a similar complex congenital cardiac malformation has not been reported in calves of the Chianina breed to date.


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