AUTHOR=Vega Génesis , Guequén Anita , Johansson Malin E. V. , Arike Liisa , Martínez-Abad Beatriz , Nyström Elisabeth E. L. , Scudieri Paolo , Pedemonte Nicoletta , Millar-Büchner Pamela , Philp Amber R. , Galietta Luis J. , Hansson Gunnar C. , Flores Carlos A. 

TITLE=Normal Calcium-Activated Anion Secretion in a Mouse Selectively Lacking TMEM16A in Intestinal Epithelium

JOURNAL=Frontiers in Physiology

VOLUME=10

YEAR=2019

URL=https://www.frontiersin.org/journals/physiology/articles/10.3389/fphys.2019.00694

DOI=10.3389/fphys.2019.00694

ISSN=1664-042X

ABSTRACT=<p>Calcium-activated anion secretion is expected to ameliorate cystic fibrosis, a genetic disease that carries an anion secretory defect in exocrine tissues. Human patients and animal models of the disease that present a mild intestinal phenotype have been postulated to bear a compensatory calcium-activated anion secretion in the intestine. TMEM16A is calcium-activated anion channel whose presence in the intestinal epithelium is contradictory. We aim to test the functional expression of TMEM16A using animal models with <italic>Cftr</italic> and/or <italic>Tmem16a</italic> intestinal silencing. Expression of TMEM16A was studied in a wild type and intestinal <italic>Tmem16a</italic> knockout mice by mRNA-seq, mass-spectrometry, q-PCR, Western blotting and immunolocalization. Calcium-activated anion secretion was recorded in the ileum and proximal colon of these animals including intestinal <italic>Cftr</italic> knockout and double mutants with dual <italic>Tmem16a</italic> and <italic>Cftr</italic> intestinal ablation. Mucus homeostasis was studied by immune-analysis of Mucin-2 (Muc2) and survival curves were recorded. <italic>Tmem16a</italic> transcript was found in intestine. Nevertheless, protein was barely detected in colon samples. Electrophysiological measurements demonstrated that the intestinal deletion of <italic>Tmem16a</italic> did not change calcium-activated anion secretion induced by carbachol or ATP in ileum and proximal colon. Muc2 architecture was not altered by <italic>Tmem16a</italic> silencing as was observed when <italic>Cftr</italic> was deleted from mouse intestine. <italic>Tmem16a</italic> silencing neither affected animal survival nor modified the lethality observed in the intestinal <italic>Cftr</italic>-null mouse. Our results demonstrate that TMEM16A function in the murine intestine is not related to electrogenic calcium-activated anion transport and does not affect mucus homeostasis and survival of animals.</p>