Figure 1.

Endogenous Ca²⁺-dependent TMEM16A and cAMP-activated CFTR Cl⁻ transport in HT₂₉ colonic epithelial cells. (A,B) YFP fluorescence quenching by iodide is enhanced by ATP in a concentration-dependent manner (n = 5 for all). siRNA knockdown of TMEM16A but not TMEM16F inhibits quenching. (C) Semiquantitative RT-PCR indicates knockdown of TMEM16A (T16A; 92%, n = 3) and TMEM16F (T16F; 93%, n = 3). (D,E) Western blotting indicating pronounced expression of endogenous TMEM16A and CFTR in HT₂₉ cells. siRNA knocked down expression of TMEM16A. (F–H) Activation of chloride conductance by IBMX and forskolin (I/F; 100 µM/2 µM) was not detected in iodide quenching (n = 5), but was significant in whole cell patch clamp recordings (overlay currents and I/V curves; n = 5). Mean ± SEM. * significant activation (p < 0.05; paired t-test). ^# significant inhibition (p < 0.05; ANOVA).