Abstract 19282: NAT10 Mutaion Causes Ciliary Aplisia and Congenital Heart Disease Associated with Heterotaxy

Introduction: We recently showed patients with CHD associated with heterotaxy can exhibit respiratory ciliary dysfunction (CD) similar to that of patients with primary ciliary dyskinesia (PCD) - a ciliopathy with airway mucociliary clearance defects. Exome sequencing analysis revealed known PCD causing mutation and rare coding variants in known PCD genes were enriched in heterotaxy patients with CD, suggesting a common etiology for heterotaxy and motile cilia dysfunction. Further interrogation for novel variants in non-PCD genes have uncovered one patient with a homozygous mutation in the acetyltransferase NAT10 . In this study, we investigated the hypothesis that NAT10 may play an essential role in ciliogenesis and is required for left-right patterning. Methods and Results: Exome sequencing was carried out in heterotaxy patients with ciliary dysfunction. Coding variants were filtered against dbSNP and 1000 genome databases. Novel homozygous coding variant in NAT10 (M638V) was identified in one heterotaxy patient with ciliary aplasia. This mutation is in a highly conserved residue of the HAT domain and is predicted to be deleterious. As NAT10 is known to acetylate tubulin, a key structural component of cilia, this seems likely to be disease causing. Using human hertRPE cells, we showed shRNA knockdown of NAT10 resulted in the inhibition of primary cilia formation. We further did NAT10 shRNA knockdown in ciliated human airway epithelial cells and showed complete repression of ciliogenesis. In contrast, reciliating airway epithelial cells treated with control shRNA formed normal motile cilia. Further analysis of zebrafish embryos after Nat10 morpholino injections showed laterality defects consistent with heterotaxy, confirming a requirement for NAT10 in left-right patterning. Conclusion: We identified a novel homozygous NAT10 mutation in heterotaxy patient with ciliary aplasia. We showed NAT10 is required for both formation of nonmotile primary cilia and motile cilia in the airway. Studies in zebrafish embryos further suggest NAT10 is required for motile cilia function regulating left-right patterning. Together these findings support the conclusion that NAT10 mutation can cause heterotaxy and ciliary aplasia phenotypes.