Calcium-Activated Cl^- Channel: Insights on the Molecular Identity in Epithelial Tissues

Calcium-activated chloride secretion in epithelial tissues has been described for many years. However, the molecular identity of the channel responsible for the Ca²⁺-activated Cl⁻ secretion in epithelial tissues has remained a mystery. More recently, TMEM16A has been identified as a new putative Ca²⁺-activated Cl⁻ channel (CaCC). The primary goal of this article will be to review the characterization of TMEM16A, as it relates to the physical structure of the channel, as well as important residues that confer voltage and Ca²⁺-sensitivity of the channel. This review will also discuss the role of TMEM16A in epithelial physiology and potential associated-pathophysiology. This will include discussion of developed knockout models that have provided much needed insight on the functional localization of TMEM16A in several epithelial tissues. Finally, this review will examine the implications of the identification of TMEM16A as it pertains to potential novel therapies in several pathologies.