title: ATP8B1-mediated spatial organization of Cdc42 signaling maintains singularity during enterocyte polarization.
abstract: During yeast cell polarization localization of the small GTPase, cell division control protein 42 homologue (Cdc42) is clustered to ensure the formation of a single bud. Here we show that the disease-associated flippase ATPase class I type 8b member 1 (ATP8B1) enables Cdc42 clustering during enterocyte polarization. Loss of this regulation results in increased apical membrane size with scattered apical recycling endosomes and permits the formation of more than one apical domain, resembling the singularity defect observed in yeast. Mechanistically, we show that to become apically clustered, Cdc42 requires the interaction between its polybasic region and negatively charged membrane lipids provided by ATP8B1. Disturbing this interaction, either by ATP8B1 depletion or by introduction of a Cdc42 mutant defective in lipid binding, increases Cdc42 mobility and results in apical membrane enlargement. Re-establishing Cdc42 clustering, by tethering it to the apical membrane or lowering its diffusion, restores normal apical membrane size in ATP8B1-depleted cells. We therefore conclude that singularity regulation by Cdc42 is conserved between yeast and human and that this regulation is required to maintain healthy tissue architecture.
authors.affiliation: Molecular Cancer Research and Cancer Genomics Netherlands, Center for Molecular Medicine, University Medical Center Utrecht, 3584 CG Utrecht, Netherlands.
authors.forename: Lucas J M
authors.initials: LJ
authors.lastname: Bruurs
authors.affiliation: Molecular Cancer Research and Cancer Genomics Netherlands, Center for Molecular Medicine, University Medical Center Utrecht, 3584 CG Utrecht, Netherlands.
authors.forename: Lisa
authors.initials: L
authors.lastname: Donker
authors.affiliation: Molecular Cancer Research and Cancer Genomics Netherlands, Center for Molecular Medicine, University Medical Center Utrecht, 3584 CG Utrecht, Netherlands.
authors.forename: Susan
authors.initials: S
authors.lastname: Zwakenberg
authors.affiliation: Molecular Cancer Research and Cancer Genomics Netherlands, Center for Molecular Medicine, University Medical Center Utrecht, 3584 CG Utrecht, Netherlands.
authors.forename: Fried J
authors.initials: FJ
authors.lastname: Zwartkruis
authors.affiliation: Hubrecht Institute, Royal Netherlands Academy of Arts and Sciences (KNAW) and University Medical Center Utrecht, 3508 AD Utrecht, Netherlands.
authors.forename: Harry
authors.initials: H
authors.lastname: Begthel
authors.affiliation: Institute of Liver Studies, King's College Hospital, London SE5 9RS, England, UK.
authors.forename: A S
authors.initials: AS
authors.lastname: Knisely
authors.affiliation: Department of Cell Biology, Center for Molecular Medicine, University Medical Center Utrecht, 3584 CG Utrecht, Netherlands.
authors.forename: George
authors.initials: G
authors.lastname: Posthuma
authors.affiliation: Tytgat Institute for Liver and Intestinal Research, Academic Medical Centre, 1105 AZ Amsterdam, Netherlands.
authors.forename: Stan F J
authors.initials: SF
authors.lastname: van de Graaf
authors.affiliation: Tytgat Institute for Liver and Intestinal Research, Academic Medical Centre, 1105 AZ Amsterdam, Netherlands.
authors.forename: Coen C
authors.initials: CC
authors.lastname: Paulusma
authors.affiliation: Molecular Cancer Research and Cancer Genomics Netherlands, Center for Molecular Medicine, University Medical Center Utrecht, 3584 CG Utrecht, Netherlands J.L.Bos@umcutrecht.nl.
authors.forename: Johannes L
authors.initials: JL
authors.lastname: Bos
mesh_terms: D000251:Adenosine Triphosphatases / Q000235:genetics / Q000378:metabolism*; D000818:Animals; D002460:Cell Line; D016764:Cell Polarity / Q000502:physiology*; D020895:Enterocytes / Q000166:cytology / Q000378:metabolism*; D006801:Humans; D008563:Membrane Lipids / Q000235:genetics / Q000378:metabolism*; D051379:Mice; D049294:Phospholipid Transfer Proteins / Q000235:genetics / Q000378:metabolism*; D015398:Signal Transduction / Q000502:physiology*; D020764:cdc42 GTP-Binding Protein / Q000235:genetics / Q000378:metabolism*
chemical_list: C581598:Cdc42 protein, mouse; D008563:Membrane Lipids; D049294:Phospholipid Transfer Proteins; D000251:Adenosine Triphosphatases; C491742:Atp8b1 protein, mouse; D020764:cdc42 GTP-Binding Protein