AUTHOR=So Juhoon , Ningappa Mylarappa , Glessner Joseph , Min Jun , Ashokkumar Chethan , Ranganathan Sarangarajan , Higgs Brandon W. , Li Dong , Sun Qing , Schmitt Lori , Biery Amy C. , Dobrowolski Steven , Trautz Christine , Fuhrman Leah , Schwartz Molly Christine , Klena Nikolai Thomas , Fusco Joseph , Prasadan Krishna , Adenuga Morayooluwa , Mohamed Nada , Yan Qi , Chen Wei , Horne William , Dhawan Anil , Sharif Khalid , Kelly Deirdre , Squires Robert H , Gittes George K. , Hakonarson Hakon , Morell Victor , Lo Cecilia , Subramaniam Shankar , Shin Donghun , Sindhi Rakesh 

TITLE=Biliary-Atresia-Associated Mannosidase-1-Alpha-2 Gene Regulates Biliary and Ciliary Morphogenesis and Laterality

JOURNAL=Frontiers in Physiology

VOLUME=11

YEAR=2020

URL=https://www.frontiersin.org/journals/physiology/articles/10.3389/fphys.2020.538701

DOI=10.3389/fphys.2020.538701

ISSN=1664-042X

ABSTRACT=<sec><title>Background/Aims</title><p>Infectious and genetic factors are invoked, respectively in isolated biliary atresia (BA), or syndromic BA, with major extrahepatic anomalies. However, isolated BA is also associated with minor extrahepatic gut and cardiovascular anomalies and multiple susceptibility genes, suggesting common origins.</p></sec><sec><title>Methods</title><p>We investigated novel susceptibility genes with genome-wide association, targeted sequencing and tissue staining in BA requiring liver transplantation, independent of BA subtype. Candidate gene effects on morphogenesis, developmental pathways, and ciliogenesis, which regulates left-right patterning were investigated with zebrafish knockdown and mouse knockout models, mouse airway cell cultures, and liver transcriptome analysis.</p></sec><sec><title>Results</title><p>Single nucleotide polymorphisms in Mannosidase-1-α-2 (<italic>MAN1A2</italic>) were significantly associated with BA and with other polymorphisms known to affect <italic>MAN1A2</italic> expression but were not differentially enriched in either BA subtype. In zebrafish embryos, <italic>man1a2</italic> knockdown caused poor biliary network formation, ciliary dysgenesis in Kupffer’s vesicle, cardiac and liver heterotaxy, and dysregulated <italic>egfra</italic> and other developmental genes. Suboptimal <italic>man1a2</italic> knockdown synergized with suboptimal EGFR signaling or suboptimal knockdown of the EGFR pathway gene, adenosine-ribosylation-factor-6, which had minimal effects individually, to reproduce biliary defects but not heterotaxy. In cultured mouse airway epithelium, <italic>Man1a2</italic> knockdown arrested ciliary development and motility. <italic>Man1a2</italic><sup>–/–</sup> mice, which experience respiratory failure, also demonstrated portal and bile ductular inflammation. Human BA liver and <italic>Man1a2</italic><sup>–/–</sup> liver exhibited reduced <italic>Man1a2</italic> expression and dysregulated ciliary genes, known to cause multisystem human laterality defects.</p></sec><sec><title>Conclusion</title><p>BA requiring transplantation associates with sequence variants in <italic>MAN1A2</italic>. <italic>man1a2</italic> regulates laterality, in addition to hepatobiliary morphogenesis, by regulating ciliogenesis in zebrafish and mice, providing a novel developmental basis for multisystem defects in BA.</p></sec>