title: Rab8a vesicles regulate Wnt ligand delivery and Paneth cell maturation at the intestinal stem cell niche.
abstract: Communication between stem and niche supporting cells maintains the homeostasis of adult tissues. Wnt signaling is a crucial regulator of the stem cell niche, but the mechanism that governs Wnt ligand delivery in this compartment has not been fully investigated. We identified that Wnt secretion is partly dependent on Rab8a-mediated anterograde transport of Gpr177 (wntless), a Wnt-specific transmembrane transporter. Gpr177 binds to Rab8a, depletion of which compromises Gpr177 traffic, thereby weakening the secretion of multiple Wnts. Analyses of generic Wnt/β-catenin targets in Rab8a knockout mouse intestinal crypts indicate reduced signaling activities; maturation of Paneth cells - a Wnt-dependent cell type - is severely affected. Rab8a knockout crypts show an expansion of Lgr5(+) and Hopx(+) cells in vivo. However, in vitro, the knockout enteroids exhibit significantly weakened growth that can be partly restored by exogenous Wnts or Gsk3β inhibitors. Immunogold labeling and surface protein isolation identified decreased plasma membrane localization of Gpr177 in Rab8a knockout Paneth cells and fibroblasts. Upon stimulation by exogenous Wnts, Rab8a-deficient cells show ligand-induced Lrp6 phosphorylation and transcriptional reporter activation. Rab8a thus controls Wnt delivery in producing cells and is crucial for Paneth cell maturation. Our data highlight the profound tissue plasticity that occurs in response to stress induced by depletion of a stem cell niche signal.
authors.affiliation: Department of Biological Sciences, Rutgers University, Newark, NJ 07102, USA.
authors.forename: Soumyashree
authors.initials: S
authors.lastname: Das
authors.affiliation: Department of Biological Sciences, Rutgers University, Newark, NJ 07102, USA.
authors.forename: Shiyan
authors.initials: S
authors.lastname: Yu
authors.affiliation: Department of Biological Sciences, Rutgers University, Newark, NJ 07102, USA.
authors.forename: Ryotaro
authors.initials: R
authors.lastname: Sakamori
authors.affiliation: Department of Biological Sciences, Rutgers University, Newark, NJ 07102, USA.
authors.forename: Pavan
authors.initials: P
authors.lastname: Vedula
authors.affiliation: Department of Biological Sciences, Rutgers University, Newark, NJ 07102, USA.
authors.forename: Qiang
authors.initials: Q
authors.lastname: Feng
authors.affiliation: Department of Biological Sciences, Rutgers University, Newark, NJ 07102, USA.
authors.forename: Juan
authors.initials: J
authors.lastname: Flores
authors.affiliation: Department of Genetics, Human Genetics Institute of New Jersey, Rutgers University, Piscataway, NJ 08854, USA.
authors.forename: Andrew
authors.initials: A
authors.lastname: Hoffman
authors.affiliation: Department of Biomedical Genetics, Center for Oral Biology, James P. Wilmot Cancer Center, Stem Cell and Regenerative Medicine Institute, University of Rochester Medical Center, Rochester, NY 14642, USA.
authors.forename: Jiang
authors.initials: J
authors.lastname: Fu
authors.affiliation: Department of Biological Sciences, Rutgers University, Newark, NJ 07102, USA.
authors.forename: Ewa
authors.initials: E
authors.lastname: Stypulkowski
authors.affiliation: Department of Biological Sciences, Rutgers University, Newark, NJ 07102, USA.
authors.forename: Alexis
authors.initials: A
authors.lastname: Rodriguez
authors.affiliation: Department of Biological Sciences, Rutgers University, Newark, NJ 07102, USA.
authors.forename: Radek
authors.initials: R
authors.lastname: Dobrowolski
authors.affiliation: Department of Cell Biology, Graduate School of Medicine, Osaka University 2-2, Yamadaoka, Suita, Osaka 565-0871, Japan.
authors.forename: Akihiro
authors.initials: A
authors.lastname: Harada
authors.affiliation: Department of Biomedical Genetics, Center for Oral Biology, James P. Wilmot Cancer Center, Stem Cell and Regenerative Medicine Institute, University of Rochester Medical Center, Rochester, NY 14642, USA.
authors.forename: Wei
authors.initials: W
authors.lastname: Hsu
authors.affiliation: Department of Biological Sciences, Rutgers University, Newark, NJ 07102, USA.
authors.forename: Edward M
authors.initials: EM
authors.lastname: Bonder
authors.affiliation: Department of Genetics, Human Genetics Institute of New Jersey, Rutgers University, Piscataway, NJ 08854, USA Rutgers Cancer Institute of New Jersey, New Brunswick, NJ 08901, USA.
authors.forename: Michael P
authors.initials: MP
authors.lastname: Verzi
authors.affiliation: Department of Biological Sciences, Rutgers University, Newark, NJ 07102, USA Rutgers Cancer Institute of New Jersey, New Brunswick, NJ 08901, USA ngao@andromeda.rutgers.edu.
authors.forename: Nan
authors.initials: N
authors.lastname: Gao
mesh_terms: D000818:Animals; D049109:Cell Proliferation; D002478:Cells, Cultured; D038362:Glycogen Synthase Kinase 3 / Q000037:antagonists & inhibitors; D000071679:Glycogen Synthase Kinase 3 beta; D018398:Homeodomain Proteins / Q000378:metabolism; D006801:Humans; D047908:Intracellular Signaling Peptides and Proteins / Q000378:metabolism; D060488:Low Density Lipoprotein Receptor-Related Protein-6 / Q000378:metabolism; D051379:Mice; D018345:Mice, Knockout; D019879:Paneth Cells / Q000166:cytology*; D010766:Phosphorylation; D043562:Receptors, G-Protein-Coupled / Q000378:metabolism; D055153:Stem Cell Niche / Q000502:physiology*; D013234:Stem Cells / Q000166:cytology*; D015533:Transcriptional Activation; D051153:Wnt Proteins / Q000378:metabolism; D060449:Wnt Signaling Pathway; D051176:beta Catenin / Q000378:metabolism; D020691:rab GTP-Binding Proteins / Q000235:genetics / Q000378:metabolism*
chemical_list: C545200:Gpr177 protein, mouse; D018398:Homeodomain Proteins; D047908:Intracellular Signaling Peptides and Proteins; C493597:Lgr5 protein, mouse; D060488:Low Density Lipoprotein Receptor-Related Protein-6; C555476:Lrp6 protein, mouse; C546061:Rab8a protein, mouse; D043562:Receptors, G-Protein-Coupled; D051153:Wnt Proteins; D051176:beta Catenin; C000605506:GSK3B protein, human; D000071679:Glycogen Synthase Kinase 3 beta; C000605507:Gsk3b protein, mouse; D038362:Glycogen Synthase Kinase 3; D020691:rab GTP-Binding Proteins
keywords: Gpr177; Intestinal stem cell; Paneth cell; Rab8a; Wnt secretion; Wntless