TMEM16A (ANO1) is a calcium-activated chloride channel (CaCC) expressed in secretory epithelia, smooth muscle, and other tissues. Cell-based functional screening of ∼110,000 compounds revealed compounds that activated TMEM16A CaCC conductance without increasing cytoplasmic Ca 2+. By patch-clamp, N-aroylaminothiazole "activators" (E act) strongly increased Cl - current at 0 Ca 2+, whereas tetrazolylbenzamide "potentiators" (F act) were not active at 0 Ca 2+ but reduced the EC 50 for Ca 2+- dependent TMEM16A activation. Of 682 analogs tested, the most potent activator (E act) and potentiator (F act) produced large and more sustained CaCC Cl -currents than general agonists of Ca 2+ signaling, with EC 50 3-6 μM and Cl - conductance comparable to that induced transiently by Ca 2+-elevating purinergic agonists. Analogs of activators were identified that fully inhibited TMEM16A Cl - conductance, providing further evidence for direct TMEM16A binding. The TMEM16A activators increased CaCC conductance in human salivary and airway submucosal gland epithelial cells, and IL-4 treated bronchial cells, and stimulated submucosal gland secretion in human bronchi and smooth muscle contraction in mouse intestine. Small-molecule, TMEM16A-targeted activators may be useful for drug therapy of cystic fibrosis, dry mouth, and gastrointestinal hypomotility disorders, and for pharmacological dissection of TMEM16A function.
All Science Journal Classification (ASJC) codes
- Molecular Biology