title: LGR5 deficiency deregulates Wnt signaling and leads to precocious Paneth cell differentiation in the fetal intestine.
abstract: The orphan Leucine-rich repeat G protein-coupled receptor 5 (LGR5/GPR49), a target of Wnt signaling, is a marker of adult intestinal stem cells (SC). However, neither its function in the adults, nor during development of the intestine have been addressed yet. In this report, we investigated the role of LGR5 during ileal development by using LGR5 null/LacZ-NeoR knock-in mice. X-gal staining experiments showed that, after villus morphogenesis, Lgr5 expression becomes restricted to dividing cells clustered in the intervillus region and is more pronounced in the distal small intestine. At day E18.5, LGR5 deficiency leads to premature Paneth cell differentiation in the small intestine without detectable effects on differentiation of other cell lineages, nor on epithelial cell proliferation or migration. Quantitative RT-PCR experiments showed that expression from the LGR5 promoter was upregulated in LGR5-null mice, pointing to the existence of an autoregulatory negative feedback loop in intact animals. This deregulation was associated with overexpression of Wnt target genes in the intervillus epithelium. Transcriptional profiling of mutant mice ileums revealed that LGR5 function is associated with expression of SC and SC niche markers. Together, our data identify LGR5 as a negative regulator of the Wnt pathway in the developing intestine.
authors.affiliation: Institut de Recherche Interdisciplinaire en Biologie Humaine et Moléculaire (IRIBHM), Faculty of Medicine, Université Libre de Bruxelles, 1070 Brussels, Belgium.
authors.forename: Marie Isabelle
authors.initials: MI
authors.lastname: Garcia
authors.forename: Mariangela
authors.initials: M
authors.lastname: Ghiani
authors.forename: Anne
authors.initials: A
authors.lastname: Lefort
authors.forename: Frédérick
authors.initials: F
authors.lastname: Libert
authors.forename: Sandra
authors.initials: S
authors.lastname: Strollo
authors.forename: Gilbert
authors.initials: G
authors.lastname: Vassart
mesh_terms: D000818:Animals; D001483:Base Sequence; D001973:Bromodeoxyuridine; D002454:Cell Differentiation; D002455:Cell Division; D002465:Cell Movement; D017931:DNA Primers; D047108:Embryonic Development / Q000235:genetics; D005260:Female; D015870:Gene Expression; D018507:Gene Expression Regulation, Developmental; D007082:Ileum / Q000196:embryology; D017403:In Situ Hybridization; D007421:Intestine, Small / Q000166:cytology / Q000196:embryology*; D051379:Mice; D008810:Mice, Inbred C57BL; D008969:Molecular Sequence Data; D020411:Oligonucleotide Array Sequence Analysis; D019879:Paneth Cells / Q000166:cytology*; D011247:Pregnancy; D043562:Receptors, G-Protein-Coupled / Q000172:deficiency / Q000235:genetics*; D020133:Reverse Transcriptase Polymerase Chain Reaction; D014158:Transcription, Genetic; D051153:Wnt Proteins / Q000502:physiology*
chemical_list: D017931:DNA Primers; C493597:Lgr5 protein, mouse; D043562:Receptors, G-Protein-Coupled; D051153:Wnt Proteins; D001973:Bromodeoxyuridine