title: Robust cre-mediated recombination in small intestinal stem cells utilizing the olfm4 locus.
abstract: The epithelium of the small intestine is the most rapidly self-renewing tissue in mammals. We previously demonstrated the existence of a long-lived pool of cycling stem cells defined by Lgr5 expression at the bottom of intestinal crypts. An Lgr5-eGFP-IRES-CreERT2 knockin allele has been instrumental in characterizing and profiling these cells, yet its low level expression and its silencing in patches of adjacent crypts have not allowed quantitative gene deletion. Olfactomedin-4 (Olfm4) has emerged from a gene signature of Lgr5 stem cells as a robust marker for murine small intestinal stem cells. We observe that Olfm4(null) animals show no phenotype and report the generation of an Olfm4-IRES-eGFPCreERT2 knockin mouse model that allows visualization and genetic manipulation of Lgr5+ stem cells in the epithelium of the small intestine. The eGFPCreERT2 fusion protein faithfully marks all stem cells in the small intestine and induces the activation of a conditional LacZ reporter with robust efficiency.
authors.affiliation: Hubrecht Institute for Developmental Biology and Stem Cells, University Medical Centre Utrecht, University of Utrecht, Utrecht, Uppsalalaan 8, 3584CT Utrecht, the Netherlands.
authors.forename: Jurian
authors.initials: J
authors.lastname: Schuijers
authors.affiliation: Hubrecht Institute for Developmental Biology and Stem Cells, University Medical Centre Utrecht, University of Utrecht, Utrecht, Uppsalalaan 8, 3584CT Utrecht, the Netherlands.
authors.forename: Laurens G
authors.initials: LG
authors.lastname: van der Flier
authors.affiliation: Hubrecht Institute for Developmental Biology and Stem Cells, University Medical Centre Utrecht, University of Utrecht, Utrecht, Uppsalalaan 8, 3584CT Utrecht, the Netherlands.
authors.forename: Johan
authors.initials: J
authors.lastname: van Es
authors.affiliation: Hubrecht Institute for Developmental Biology and Stem Cells, University Medical Centre Utrecht, University of Utrecht, Utrecht, Uppsalalaan 8, 3584CT Utrecht, the Netherlands. Electronic address: h.clevers@hubrecht.eu.
authors.forename: Hans
authors.initials: H
authors.lastname: Clevers
mesh_terms: D000483:Alleles; D000818:Animals; D019070:Cell Lineage; D002478:Cells, Cultured; D055785:Gene Knockdown Techniques; D056426:Genetic Loci; D006023:Glycoproteins / Q000235:genetics*; D019426:Integrases / Q000235:genetics; D007421:Intestine, Small / Q000166:cytology*; D051379:Mice; D008810:Mice, Inbred C57BL; D010641:Phenotype; D043562:Receptors, G-Protein-Coupled / Q000378:metabolism; D011995:Recombination, Genetic; D013234:Stem Cells / Q000166:cytology* / Q000378:metabolism
chemical_list: D006023:Glycoproteins; C493597:Lgr5 protein, mouse; D043562:Receptors, G-Protein-Coupled; C584470:olfactomedin 4, mouse; C045073:Cre recombinase; D019426:Integrases