TTC7A mutations disrupt intestinal epithelial apicobasal polarity
Amélie E. Bigorgne, Henner F. Farin, Roxane Lemoine, Nizar Mahlaoui, Nathalie Lambert, Marine Gil, Ansgar Schulz, Pierre Philippet, Patrick Schlesser, Tore G. Abrahamsen, Knut Oymar, E. Graham Davies, Christian Lycke Ellingsen, Emmanuelle Leteurtre, Brigitte Moreau-Massart, Dominique Berrebi, Christine Bole-Feysot, Patrick Nischke, Nicole Brousse, Alain Fischer, Hans Clevers, Geneviève de Saint Basile
Amélie E. Bigorgne, Henner F. Farin, Roxane Lemoine, Nizar Mahlaoui, Nathalie Lambert, Marine Gil, Ansgar Schulz, Pierre Philippet, Patrick Schlesser, Tore G. Abrahamsen, Knut Oymar, E. Graham Davies, Christian Lycke Ellingsen, Emmanuelle Leteurtre, Brigitte Moreau-Massart, Dominique Berrebi, Christine Bole-Feysot, Patrick Nischke, Nicole Brousse, Alain Fischer, Hans Clevers, Geneviève de Saint Basile
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Research Article Gastroenterology

TTC7A mutations disrupt intestinal epithelial apicobasal polarity

Abstract

Multiple intestinal atresia (MIA) is a rare cause of bowel obstruction that is sometimes associated with a combined immunodeficiency (CID), leading to increased susceptibility to infections. The factors underlying this rare disease are poorly understood. We characterized the immunological and intestinal features of 6 unrelated MIA-CID patients. All patients displayed a profound, generalized lymphocytopenia, with few lymphocytes present in the lymph nodes. The thymus was hypoplastic and exhibited an abnormal distribution of epithelial cells. Patients also had profound disruption of the epithelial barrier along the entire gastrointestinal tract. Using linkage analysis and whole-exome sequencing, we identified 10 mutations in tetratricopeptide repeat domain–7A (TTC7A), all of which potentially abrogate TTC7A expression. Intestinal organoid cultures from patient biopsies displayed an inversion of apicobasal polarity of the epithelial cells that was normalized by pharmacological inhibition of Rho kinase. Our data indicate that TTC7A deficiency results in increased Rho kinase activity, which disrupts polarity, growth, and differentiation of intestinal epithelial cells, and which impairs immune cell homeostasis, thereby promoting MIA-CID development.

Authors

Amélie E. Bigorgne, Henner F. Farin, Roxane Lemoine, Nizar Mahlaoui, Nathalie Lambert, Marine Gil, Ansgar Schulz, Pierre Philippet, Patrick Schlesser, Tore G. Abrahamsen, Knut Oymar, E. Graham Davies, Christian Lycke Ellingsen, Emmanuelle Leteurtre, Brigitte Moreau-Massart, Dominique Berrebi, Christine Bole-Feysot, Patrick Nischke, Nicole Brousse, Alain Fischer, Hans Clevers, Geneviève de Saint Basile

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Figure 2

Pedigree and TTC7A mutations in MIA-CID families.

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Pedigree and TTC7A mutations in MIA-CID families. (A) MIA-CID family p...
(A) MIA-CID family pedigree. Square, male; circle, female; completely filled symbols, affected individuals; half-filled symbols, heterozygous carriers. Affected individuals who did not undergo genetic testing are indicated in gray. Slashes indicate deceased persons; double horizontal lines indicate consanguinity. A7 has been described previously (8). (B) TTC7A gene mutations and their predicted effect on the TTC7A protein. TPRs are indicated on the protein sequence, in accordance with NCBI human sequence annotation (accession no. Q9ULTO-1).