An inducible mouse model for microvillus inclusion disease reveals a role for myosin Vb in apical and basolateral trafficking

• Published in: Proceedings of the National Academy of Sciences - PNAS Vol. 112; no. 40; pp. 12408 - 12413
• Main Authors: Schneeberger, Kerstin, Vogel, Georg F., Teunissen, Hans, van Ommen, Domenique D., Begthel, Harry, Bouazzaoui, Layla El, van Vugt, Anke H. M., Beekman, Jeffrey M., Klumperman, Judith, Müller, Thomas, Janecke, Andreas, Gerner, Patrick, Huber, Lukas A., Hess, Michael W., Clevers, Hans, van Es, Johan H., Nieuwenhuis, Edward E. S., Middendorp, Sabine
• Format: Journal Article
• Language: English
• Published: United States National Academy of Sciences 06-10-2015; National Acad Sciences
• Subjects: Animals; Biological Sciences; Diarrhea; Disease Models, Animal; Electron microscopy; Enterocytes - metabolism; Enterocytes - pathology; Enterocytes - ultrastructure; Epithelial Cells - metabolism; Epithelial Cells - pathology; Epithelial Cells - ultrastructure; Female; Genotype & phenotype; Humans; Immunohistochemistry; Intestines - metabolism; Intestines - pathology; Intestines - ultrastructure; Malabsorption Syndromes - chemically induced; Malabsorption Syndromes - metabolism; Male; Mice, Inbred C57BL; Mice, Inbred CBA; Mice, Knockout; Mice, Transgenic; Microscopy, Confocal; Microscopy, Electron, Transmission; Microvilli - metabolism; Microvilli - pathology; Microvilli - ultrastructure; Mucolipidoses - chemically induced; Mucolipidoses - metabolism; Mutation; Myosin Type V - genetics; Myosin Type V - metabolism; Organ Culture Techniques; Physiology; Protein Transport - genetics; Protein Transport - physiology; Rodents; Tamoxifen; epithelila polarity; intestinal enteropathy; microvillus inclusion disease; myosin Vb; mouse model
• ISSN: 0027-8424; 1091-6490
• DOI: 10.1073/pnas.1516672112

Microvillus inclusion disease (MVID) is a rare intestinal enteropathy with an onset within a few days to months after birth, resulting in persistent watery diarrhea. Mutations in the myosin Vb gene (MYO5B) have been identified in the majority of MVID patients. However, the exact pathophysiology of MVID still remains unclear. To address the specific role of MYO5B in the intestine, we generated an intestine-specific conditionalMyo5b-deficient (Myo5bfl/fl;Vil-CreERT2) mouse model. We analyzed intestinal tissues and cultured organoids ofMyo5bfl/fl;Vil-CreERT2mice by electron microscopy, immunofluorescence, and immunohistochemistry. Our data showed thatMyo5bfl/fl;Vil-CreERT2mice developed severe diarrhea within 4 d after tamoxifen induction. Periodic Acid Schiff and alkaline phosphatase staining revealed subapical accumulation of intracellular vesicles in villus enterocytes. Analysis by electron microscopy confirmed an almost complete absence of apical microvilli, the appearance of microvillus inclusions, and enlarged intercellular spaces in inducedMyo5bfl/fl;Vil-CreERT2intestines. In addition, we determined that MYO5B is involved not only in apical but also basolateral trafficking of proteins. The analysis of the intestine during the early onset of the disease revealed that subapical accumulation of secretory granules precedes occurrence of microvillus inclusions, indicating involvement of MYO5B in early differentiation of epithelial cells. By comparing our data with a novel MVID patient, we conclude that our mouse model completely recapitulates the intestinal phenotype of human MVID. This includes severe diarrhea, loss of microvilli, occurrence of microvillus inclusions, and subapical secretory granules. Thus, loss of MYO5B disturbs both apical and basolateral trafficking of proteins and causes MVID in mice.