title: Microvillus inclusion disease: loss of Myosin vb disrupts intracellular traffic and cell polarity.
abstract: Microvillus inclusion disease (MVID) is a congenital enteropathy characterized by loss of apical microvilli and formation of cytoplasmic inclusions lined by microvilli in enterocytes. MVID is caused by mutations in the MYO5B gene, coding for the myosin Vb motor protein. Although myosin Vb is implicated in the organization of intracellular transport and cell surface polarity in epithelial cells, its precise role in the pathogenesis of MVID is unknown. We performed correlative immunohistochemistry analyses of sections from duodenal biopsies of a MVID patient, compound heterozygous for two novel MYO5B mutations, predicting loss of function of myosin Vb in duodenal enterocytes together with a stable MYO5B CaCo2 RNAi cell system. Our findings show that myosin Vb-deficient enterocytes display disruption of cell polarity as reflected by mislocalized apical and basolateral transporter proteins, altered distribution of certain endosomal/lysosomal constituents including Rab GTPases. Together, this severe disturbance of epithelial cell function could shed light on the pathology and symptoms of MVID.
authors.affiliation: Division of Cell Biology, Biocenter Innsbruck, Medical University Innsbruck, Innsbruck, Austria; Division of Pathology, Department of Pediatric Laboratory Medicine, Hospital for Sick Children, Toronto, Canada.
authors.forename: Cornelia E
authors.initials: CE
authors.lastname: Thoeni
authors.forename: Georg F
authors.initials: GF
authors.lastname: Vogel
authors.forename: Ivan
authors.initials: I
authors.lastname: Tancevski
authors.forename: Stephan
authors.initials: S
authors.lastname: Geley
authors.forename: Silvia
authors.initials: S
authors.lastname: Lechner
authors.forename: Kristian
authors.initials: K
authors.lastname: Pfaller
authors.forename: Michael W
authors.initials: MW
authors.lastname: Hess
authors.forename: Thomas
authors.initials: T
authors.lastname: Müller
authors.forename: Andreas R
authors.initials: AR
authors.lastname: Janecke
authors.forename: Yaron
authors.initials: Y
authors.lastname: Avitzur
authors.forename: Aleixo
authors.initials: A
authors.lastname: Muise
authors.forename: Ernest
authors.initials: E
authors.lastname: Cutz
authors.forename: Lukas A
authors.initials: LA
authors.lastname: Huber
mesh_terms: D045744:Cell Line, Tumor; D016764:Cell Polarity; D020895:Enterocytes / Q000378:metabolism / Q000473:pathology; D006579:Heterozygote; D006801:Humans; D007231:Infant, Newborn; D008286:Malabsorption Syndromes / Q000175:diagnosis / Q000235:genetics / Q000378:metabolism*; D008297:Male; D008871:Microvilli / Q000235:genetics / Q000378:metabolism / Q000473:pathology*; D009081:Mucolipidoses / Q000175:diagnosis / Q000235:genetics / Q000378:metabolism*; D009154:Mutation; D018995:Myosin Heavy Chains / Q000235:genetics / Q000378:metabolism*; D024701:Myosin Type V / Q000235:genetics / Q000378:metabolism*; D021381:Protein Transport
chemical_list: C505832:MYO5B protein, human; D024701:Myosin Type V; D018995:Myosin Heavy Chains
keywords: MYO5B mutations; congenital enteropathies; epithelial cell polarity; intracellular trafficking; microvillus inclusion disease; myosin Vb; protracted diarrhea