title: Rare LRP6 variants identified in spina bifida patients.
abstract: Several single-nucleotide variants (SNVs) in low-density lipoprotein receptor-related protein 6 (Lrp6) cause neural tube defects (NTDs) in mice. We therefore examined LRP6 in 192 unrelated infants from California with the NTD, spina bifida, and found four heterozygous missense SNVs, three of which were predicted to be deleterious, among NTD cases and not in 190 ethnically matched nonmalformed controls. Parents and siblings could not be tested because of the study design. Like Crooked tail and Ringleschwanz mouse variants, the p.Tyr544Cys Lrp6 protein failed to bind the chaperone protein mesoderm development and impaired Lrp6 subcellular localization to the plasma membrane of MDCK II cells. Only the p.Tyr544Cys Lrp6 variant downregulated canonical Wnt signaling in a TopFlash luciferase reporter in vitro assay. In contrast, three Lrp6 mutants (p.Ala3Val, p.Tyr544Cys, and p.Arg1574Leu) increased noncanonical Wnt/planar cell polarity (PCP) signaling in an Ap1-luciferase assay. Thus, LRP6 variants outside of YWTD repeats could potentially predispose embryos to NTDs, whereas Lrp6 modulation of Wnt/PCP signaling would be more essential than its canonical pathway role in neural tube closure.
authors.affiliation: Dell Pediatric Research Institute, Department of Nutritional Sciences, The University of Texas at Austin, Austin, Texas.
authors.forename: Yunping
authors.initials: Y
authors.lastname: Lei
authors.forename: Kristin
authors.initials: K
authors.lastname: Fathe
authors.forename: Danielle
authors.initials: D
authors.lastname: McCartney
authors.forename: Huiping
authors.initials: H
authors.lastname: Zhu
authors.forename: Wei
authors.initials: W
authors.lastname: Yang
authors.forename: M Elizabeth
authors.initials: ME
authors.lastname: Ross
authors.forename: Gary M
authors.initials: GM
authors.lastname: Shaw
authors.forename: Richard H
authors.initials: RH
authors.lastname: Finnell
mesh_terms: D000818:Animals; D002460:Cell Line; D006801:Humans; D007223:Infant; D060488:Low Density Lipoprotein Receptor-Related Protein-6 / Q000235:genetics* / Q000378:metabolism; D051379:Mice; D020641:Polymorphism, Single Nucleotide; D020033:Protein Isoforms / Q000235:genetics / Q000378:metabolism; D016135:Spinal Dysraphism / Q000235:genetics*; D060449:Wnt Signaling Pathway
chemical_list: C555475:LRP6 protein, human; D060488:Low Density Lipoprotein Receptor-Related Protein-6; D020033:Protein Isoforms
keywords: LRP6; PCP signaling; SNV; Wnt signaling; spina bifida