Talk abstracts
Talk on Wednesday 05:00-05:15pm submitted by Adrianna P. Matos-Nieves
Identification of netrin signaling in outflow tract development via transcriptomic profiling
Adrianna P. Matos-Nieves (Molecular, Cellular and Developmental Biology, The Ohio State University, Columbus, OH 43210, USA ), Uddalak Majumdar, Sathiyanarayanan Manivannan, Emily Morris (Center for Cardiovascular Research and The Heart Center, Nationwide Childrens Hospital, Columbus, OH 43205), Stephanie LaHaye (Institute for Genomic Medicine, Nationwide Childrens Hospital, Columbus, OH 43205), Vidu Garg (Departments of Pediatrics and Molecular Genetics, The Ohio State University, Columbus, OH 43210, USA )
Abstract:
Congenital heart disease (CHD) is the most common type of birth defect. Malformations involving the outflow tract (OFT) and semilunar valves account for >50% of CHD when including bicuspid aortic valve (BAV). We have previously reported that endothelial cell-derived nitric oxide activates Notch1 signaling in vitro and Notch1+/-;Nos3-/- compound mutant mice are a model of OFT malformations as they display thickened semilunar valves, BAV and ventricular septal defects with overriding aorta. In order to characterize the underlying genetic programs that govern the development of the OFT, RNA-Sequencing was performed on OFT from E13.5 Notch1+/-;Nos3-/- compound mutant and wildtype littermates. We found statistically significant changes in expression (minimum 2 fold change) in 130 genes out of 15,532 total genes as determined by one-way ANOVA. Panther pathway ontology demonstrated there were 27 pathway hits. Among these pathways, two axonal guidance signaling pathways (Slit/Robo and Netrin) where within the top 10, both containing the gene, Netrin-1. While Slit/Robo signaling has previously been demonstrated to be critical for murine cardiac OFT development, the role of Netrin signaling has not been studied. Netrin-1 was found to be downregulated (~2.4 fold) in the RNA-Seq dataset and validated by qPCR. To determine if Netrin-1 has a role in OFT development, we first examined the temporal expression pattern of Netrin-1 and its receptors Dcc, Neogenin and Unc5b by qPCR. We demonstrate that these genes are expressed in the developing E9.5 to E13.5 mouse OFT. Next, we obtained mice harboring a null-allele for Netrin-1. Netrin-1-/- display embryonic lethality by E12.5 and are currently being analyzed for embryonic cardiac malformations. Inspection of adult hearts of Netrin-1+/- mice revealed a partially penetrant (2/5) BAV phenotype. Molecular analysis of Notch1+/-;Nos3-/- embryos has implicated Netrin signaling in OFT and aortic valve development and supports further genetic investigation in human OFT malformations.
Keywords: heart development, outflow tract defects , mouse models