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Association of TMEM16A protein expression with mucous cell metaplasia of human bronchial epithelial cells

Scudieri, Paolo, Caci, Emanuela, Bruno, Silvia, Ferrara, Loretta, Schiavon, Marco, Sondo, Elvira, Tomati, Valeria, Gianotti, Ambra, Zegarra-Moran, Olga, Pedemonte, Nicoletta, Rea, Federico and Galietta, Luis J V (2012) Association of TMEM16A protein expression with mucous cell metaplasia of human bronchial epithelial cells. Journal of Physiology.


The TMEM16A membrane protein has a potential role as a Ca2+-activated Cl- channel
(CaCC) in airway epithelia. Accordingly, TMEM16A may be physiologically
important in the homeostasis of the airway surface fluid and may represent a drug
target to correct the defective Cl- secretion in cystic fibrosis. We investigated the
function and expression of TMEM16A in primary human bronchial epithelial cells
and in a bronchial cell line (CFBE41o-) using short-circuit recordings, patch-clamp
experiments, immunofluorescence, and western blots. Under resting conditions,
TMEM16A protein expression in these cells was relatively low. However,
TMEM16A silencing with specific siRNAs caused a marked inhibition of CaCC
activity thus demonstrating that a relatively low TMEM16A expression is sufficient to
support Ca2+-dependent Cl- transport. CaCC activity was also markedly inhibited
with the pharmacological inhibitor CaCCinh-A01. Following treatment for 24-72
hours with interleukin-4 (IL-4), a cytokine that induces mucous cell metaplasia, we
found that TMEM16A protein expression was strongly increased in approximately
50% of primary bronchial epithelial cells, with a specific localization in the apical
membrane. IL-4 treatment also decreased the percentage of ciliated cells and
increased that of cells expressing MUC5AC, a marker of goblet cells. Interestingly,
MUC5AC expression in epithelia treated for 24 hours with IL-4 was restricted to ~
15% of TMEM16A-positive cells. After 72 hours of treatment, the percentage of
cells co-expressing MUC5AC and TMEM16A increased to ~ 60%. In contrast,
ciliated cells showed expression of the CFTR Cl- channel but not of TMEM16A.
Our results indicate that TMEM16A protein is responsible for CaCC activity in
airway epithelial cells, particularly in cells treated with IL-4. Furthermore,
TMEM16A upregulation appears as an early event of goblet cell differentiation
induced by IL-4. These findings may suggest that TMEM16A expression is
particularly required under conditions of mucus hypersecretion to ensure adequate
secretion of electrolytes and water.

Item Type: Article
Additional Information: Literature compounds T16Ainh-A01 and CaCCinh-01 synthesised and provided by Novartis.
Date Deposited: 13 Oct 2015 13:14
Last Modified: 13 Oct 2015 13:14