title: The orphan GPCR, Gpr161, regulates the retinoic acid and canonical Wnt pathways during neurulation.
abstract: The vacuolated lens (vl) mouse mutation arose on the C3H/HeSnJ background and results in lethality, neural tube defects (NTDs) and cataracts. The vl phenotypes are due to a deletion/frameshift mutation in the orphan GPCR, Gpr161. A recent study using a null allele demonstrated that Gpr161 functions in primary cilia and represses the Shh pathway. We show the hypomorphic Gpr161(vl) allele does not severely affect the Shh pathway. To identify additional pathways regulated by Gpr161 during neurulation, we took advantage of naturally occurring genetic variation in the mouse. Previously Gpr161(vl-C3H) was crossed to different inbred backgrounds including MOLF/EiJ and the Gpr161(vl) mutant phenotypes were rescued. Five modifiers were mapped (Modvl: Modifier of vl) including Modvl5(MOLF). In this study we demonstrate the Modvl5(MOLF) congenic rescues the Gpr161(vl)-associated lethality and NTDs but not cataracts. Bioinformatics determined the transcription factor, Cdx1, is the only annotated gene within the Modvl5 95% CI co-expressed with Gpr161 during neurulation and not expressed in the eye. Using Cdx1 as an entry point, we identified the retinoid acid (RA) and canonical Wnt pathways as downstream targets of Gpr161. QRT-PCR, ISH and IHC determined that expression of RA and Wnt genes are down-regulated in Gpr161(vl/vl) but rescued by the Modvl5(MOLF) congenic during neurulation. Intraperitoneal RA injection restores expression of canonical Wnt markers and rescues Gpr161(vl/vl) NTDs. These results establish the RA and canonical Wnt as pathways downstream of Gpr161 during neurulation, and suggest that Modvl5(MOLF) bypasses the Gpr161(vl) mutation by restoring the activity of these pathways.
authors.affiliation: Center for Advanced Biotechnology and Medicine, Rutgers University, Piscataway, NJ, United States; Robert Wood Johnson Medical School, Rutgers University, Piscataway, NJ, United States. Electronic address: bl2535@columbia.edu.
authors.forename: Bo I
authors.initials: BI
authors.lastname: Li
authors.affiliation: Center for Advanced Biotechnology and Medicine, Rutgers University, Piscataway, NJ, United States; Robert Wood Johnson Medical School, Rutgers University, Piscataway, NJ, United States.
authors.forename: Paul G
authors.initials: PG
authors.lastname: Matteson
authors.affiliation: Center for Advanced Biotechnology and Medicine, Rutgers University, Piscataway, NJ, United States; Robert Wood Johnson Medical School, Rutgers University, Piscataway, NJ, United States.
authors.forename: Myka F
authors.initials: MF
authors.lastname: Ababon
authors.affiliation: Department of Genetics; Rutgers University, Piscataway, NJ, United States.
authors.forename: Alejandro Q
authors.initials: AQ
authors.lastname: Nato
authors.affiliation: Division of Biometrics, Rutgers Cancer Institute of New Jersey, New Brunswick, NJ, United States.
authors.forename: Yong
authors.initials: Y
authors.lastname: Lin
authors.affiliation: Center for Advanced Biotechnology and Medicine, Rutgers University, Piscataway, NJ, United States; Department of Biochemistry, Rutgers University, Piscataway, NJ, United States; Robert Wood Johnson Medical School, Rutgers University, Piscataway, NJ, United States.
authors.forename: Vikas
authors.initials: V
authors.lastname: Nanda
authors.affiliation: Department of Genetics; Rutgers University, Piscataway, NJ, United States.
authors.forename: Tara C
authors.initials: TC
authors.lastname: Matise
authors.affiliation: Center for Advanced Biotechnology and Medicine, Rutgers University, Piscataway, NJ, United States; Department of Neuroscience and Cell Biology, Rutgers University, Piscataway, NJ, United States; Robert Wood Johnson Medical School, Rutgers University, Piscataway, NJ, United States; Department of Genetics; Rutgers University, Piscataway, NJ, United States. Electronic address: millonig@cabm.rutgers.edu.
authors.forename: James H
authors.initials: JH
authors.lastname: Millonig
mesh_terms: D000818:Animals; D001483:Base Sequence; D002460:Cell Line; D018507:Gene Expression Regulation, Developmental; D017930:Genes, Reporter; D014644:Genetic Variation; D053823:Hedgehog Proteins / Q000378:metabolism; D018398:Homeodomain Proteins / Q000378:metabolism; D017403:In Situ Hybridization; D051379:Mice; D008809:Mice, Inbred C3H; D008822:Mice, Transgenic; D008957:Models, Genetic; D008969:Molecular Sequence Data; D009154:Mutation; D009436:Neural Tube Defects / Q000235:genetics; D054261:Neurulation; D010641:Phenotype; D040641:Quantitative Trait Loci; D012333:RNA, Messenger / Q000378:metabolism; D043562:Receptors, G-Protein-Coupled / Q000378:metabolism*; D015398:Signal Transduction; D013997:Time Factors; D014212:Tretinoin / Q000378:metabolism*; D051153:Wnt Proteins / Q000378:metabolism*; D060449:Wnt Signaling Pathway; D060509:Wnt3A Protein / Q000378:metabolism
chemical_list: C491272:Cdx1 protein, mouse; C533095:GPR161 protein, mouse; D053823:Hedgehog Proteins; D018398:Homeodomain Proteins; D012333:RNA, Messenger; D043562:Receptors, G-Protein-Coupled; C465570:Shh protein, mouse; D051153:Wnt Proteins; D060509:Wnt3A Protein; C555511:Wnt3a protein, mouse; D014212:Tretinoin
keywords: Canonical Wnt; Gpr161; Retinoic acid