UNC45A deficiency causes microvillus inclusion disease–like phenotype by impairing myosin VB–dependent apical trafficking
Rémi Duclaux-Loras, Corinne Lebreton, Jérémy Berthelet, Fabienne Charbit-Henrion, Ophelie Nicolle, Céline Revenu des Courtils, Stephanie Waich, Taras Valovka, Anis Khiat, Marion Rabant, Caroline Racine, Ida Chiara Guerrera, Júlia Baptista, Maxime M. Mahe, Michael W. Hess, Béatrice Durel, Nathalie Lefort, Céline Banal, Mélanie Parisot, Cecile Talbotec, Florence Lacaille, Emmanuelle Ecochard-Dugelay, Arzu Meltem Demir, Georg F. Vogel, Laurence Faivre, Astor Rodrigues, Darren Fowler, Andreas R. Janecke, Thomas Müller, Lukas A. Huber, Fernando Rodrigues-Lima, Frank M. Ruemmele, Holm H. Uhlig, Filippo Del Bene, Grégoire Michaux, Nadine Cerf-Bensussan, Marianna Parlato
Rémi Duclaux-Loras, Corinne Lebreton, Jérémy Berthelet, Fabienne Charbit-Henrion, Ophelie Nicolle, Céline Revenu des Courtils, Stephanie Waich, Taras Valovka, Anis Khiat, Marion Rabant, Caroline Racine, Ida Chiara Guerrera, Júlia Baptista, Maxime M. Mahe, Michael W. Hess, Béatrice Durel, Nathalie Lefort, Céline Banal, Mélanie Parisot, Cecile Talbotec, Florence Lacaille, Emmanuelle Ecochard-Dugelay, Arzu Meltem Demir, Georg F. Vogel, Laurence Faivre, Astor Rodrigues, Darren Fowler, Andreas R. Janecke, Thomas Müller, Lukas A. Huber, Fernando Rodrigues-Lima, Frank M. Ruemmele, Holm H. Uhlig, Filippo Del Bene, Grégoire Michaux, Nadine Cerf-Bensussan, Marianna Parlato
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Research Article Gastroenterology

UNC45A deficiency causes microvillus inclusion disease–like phenotype by impairing myosin VB–dependent apical trafficking

Abstract

Variants in the UNC45A cochaperone have been recently associated with a syndrome combining diarrhea, cholestasis, deafness, and bone fragility. Yet the mechanism underlying intestinal failure in UNC45A deficiency remains unclear. Here, biallelic variants in UNC45A were identified by next-generation sequencing in 6 patients with congenital diarrhea. Corroborating in silico prediction, variants either abolished UNC45A expression or altered protein conformation. Myosin VB was identified by mass spectrometry as client of the UNC45A chaperone and was found misfolded in UNC45AKO Caco-2 cells. In keeping with impaired myosin VB function, UNC45AKO Caco-2 cells showed abnormal epithelial morphogenesis that was restored by full-length UNC45A, but not by mutant alleles. Patients and UNC45AKO 3D organoids displayed altered luminal development and microvillus inclusions, while 2D cultures revealed Rab11 and apical transporter mislocalization as well as sparse and disorganized microvilli. All those features resembled the subcellular abnormalities observed in duodenal biopsies from patients with microvillus inclusion disease. Finally, microvillus inclusions and shortened microvilli were evidenced in enterocytes from unc45a-deficient zebrafish. Taken together, our results provide evidence that UNC45A plays an essential role in epithelial morphogenesis through its cochaperone function of myosin VB and that UNC45A loss causes a variant of microvillus inclusion disease.

Authors

Rémi Duclaux-Loras, Corinne Lebreton, Jérémy Berthelet, Fabienne Charbit-Henrion, Ophelie Nicolle, Céline Revenu des Courtils, Stephanie Waich, Taras Valovka, Anis Khiat, Marion Rabant, Caroline Racine, Ida Chiara Guerrera, Júlia Baptista, Maxime M. Mahe, Michael W. Hess, Béatrice Durel, Nathalie Lefort, Céline Banal, Mélanie Parisot, Cecile Talbotec, Florence Lacaille, Emmanuelle Ecochard-Dugelay, Arzu Meltem Demir, Georg F. Vogel, Laurence Faivre, Astor Rodrigues, Darren Fowler, Andreas R. Janecke, Thomas Müller, Lukas A. Huber, Fernando Rodrigues-Lima, Frank M. Ruemmele, Holm H. Uhlig, Filippo Del Bene, Grégoire Michaux, Nadine Cerf-Bensussan, Marianna Parlato

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Figure 1

Genetics of 5 families with UNC45A deficiency and molecular characterization of UNC45A variants.

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Genetics of 5 families with UNC45A deficiency and molecular characteriza...
(A) Pedigree of families with AR UNC45A deficiency (filled shapes indicate affected individuals). (B) Schematic representation of UNC45A protein showing location of the variants identified in this study. (C) Western blot analysis of UNC45A protein in HEK293T cells transfected with EV, WT, and mutant alleles (n = 2). (D) Ribbon representation of the human UNC45a model generated by MODELLER (based on the D. melanogaster and C. elegans UNC45 protein structures) showing its domain architecture. The variants were modeled in silico using Chimera. The location and a close-up view of each variant are shown. For the L237P and A838P mutations, hydrogen bonds are depicted by dark-blue dashed lines. For the T230R and E728K mutations, Van der Waals radii are represented for each atom and steric clashes occurring in the structure are shown with brown dashed lines. Coulombic surface representations are also shown. Red surface indicates the lowest electrostatic potential energy and blue the highest. Locations of the mutated residue are highlighted by a black circle. Distances are indicated using black dotted lines.