Michael W Hess1, Iris M Krainer2, Przemyslaw A Filipek2, Barbara Witting1, Karin Gutleben1, Ilja Vietor3, Heinz Zoller4, Denise Aldrian5, Ekkehard Sturm6, James R Goldenring7, Andreas R Janecke5, Thomas Müller5, Lukas A Huber3, Georg F Vogel35
1Institute of Histology and Embryology, Medical University of Innsbruck, A-6020 Innsbruck, Austria.
2Austrian Drug Screening Institute, ADSI, A-6020 Innsbruck, Austria.
3Institute of Cell Biology, Medical University of Innsbruck, A-6020 Innsbruck, Austria.
4Department of Internal Medicine, Medical University of Innsbruck, A-6020 Innsbruck, Austria.
5Department of Paediatrics I, Medical University of Innsbruck, A-6020 Innsbruck, Austria.
6Department of Paediatric Gastroenterology and Hepatology, University Hospital for Children and Adolescents, University of Tübingen, D-72076 Tübingen, Germany.
7Department of Surgery and the Epithelial Biology Center, Vanderbilt University Medical Center, Nashville, TN 37232-8240, USA.
Mutations in the actin motor protein myosinVb (myo5b) cause aberrant apical cargo transport and the congenital enteropathy microvillus inclusion disease (MVID). Recently, missense mutations in myo5b were also associated with progressive familial intrahepatic cholestasis (MYO5B-PFIC). Here, we thoroughly characterized the ultrastructural and immuno-cytochemical phenotype of hepatocytes and duodenal enterocytes from a unique case of an adult MYO5B-PFIC patient who showed constant hepatopathy but only periodic enteric symptoms. Selected data from two other patients supported the findings. Advanced methods such as cryo-fixation, freeze-substitution, immuno-gold labeling, electron tomography and immuno-fluorescence microscopy complemented the standard procedures. Liver biopsies showed mislocalization of Rab11 and bile canalicular membrane proteins. Rab11-positive vesicles clustered around bile canaliculi and resembled subapical clusters of aberrant recycling endosomes in enterocytes from MVID patients. The adult patient studied in detail showed a severe, MVID-specific enterocyte phenotype, despite only a mild clinical intestinal presentation. This included mislocalization of numerous proteins essential for apical cargo transport and morphological alterations. We characterized the heterogeneous population of large catabolic organelles regarding their complex ultrastructure and differential distribution of autophagic and lysosomal marker proteins. Finally, we generated duodenal organoids/enteroids from biopsies that recapitulated all MVID hallmarks, demonstrating the potential of this disease model for personalized medicine.