Regulation of the Ca2+-activated chloride channel Anoctamin-1 (TMEM16A) by Ca2+-induced interaction with FKBP12 and calcineurin

• Published in: Cell calcium (Edinburgh) 2020-07, Vol.89, p.102211-102211, Article 102211
• Main Authors: Sánchez-Solano, Alfredo, Corral, Nancy, Segura-Covarrubias, Guadalupe, Guzmán-Hernández, María Luisa, Arechiga-Figueroa, Ivan, Cruz-Rangel, Silvia, Pérez-Cornejo, Patricia, Arreola, Jorge
• Format: Article
• Language: English
• Subjects: Calcineurin; Calcium; Channel activation; Chloride channel; Cyclosporine A; Electrophysiology; FK506; FKBP12; Oligomerization; Rapamycin; TMEM16A
• ISSN: 0143-4160; 1532-1991
• DOI: 10.1016/j.ceca.2020.102211

[Display omitted] •Critical physiological functions depend on the anion channel Anoctamin 1 (ANO1) function.•ANO1 forms a complex with FKBP12 and calcineurin when intracellular calcium increase.•Inhibition of FKBP12 and calcineurin decreased ANO1 activity.•Detaching FKBP12-calcineurin with FK506 does not terminate ANO1 function.•When intracellular calcium increase complex formation maintains ANO1 activity. Chloride fluxes through the calcium-gated chloride channel Anoctamin-1 (TMEM16A) control blood pressure, secretion of saliva, mucin, insulin, and melatonin, gastrointestinal motility, sperm capacitation and motility, and pain sensation. Calcium activates a myriad of regulatory proteins but how these proteins affect TMEM16A activity is unresolved. Here we show by co-immunoprecipitation that increasing intracellular calcium with ionomycin or by activating sphingosine-1-phosphate receptors, induces coupling of calcium/calmodulin-dependent phosphatase calcineurin and prolyl isomerase FK506-binding protein 12 (FKBP12) to TMEM16A in HEK-293 cells. Application of drugs that target either calcineurin (cyclosporine A) or FKBP12 (tacrolimus known as FK506 and sirolimus known as rapamycin) caused a decrease in TMEM16A activity. In addition, FK506 and BAPTA-AM prevented co-immunoprecipitation between FKBP12 and TMEM16A. FK506 rendered the channel insensitive to cyclosporine A without altering its apparent calcium sensitivity whereas zero intracellular calcium blocked the effect of FK506. Rapamycin decreased TMEM16A activity in cells pre-treated with cyclosporine A or FK506. These results suggest the formation of a TMEM16A-FKBP12-calcineurin complex that regulates channel function. We conclude that upon a cytosolic calcium increase the TMEM16A-FKPB12-calcineurin trimers are assembled. Such hetero-oligomerization enhances TMEM16A channel activity but is not mandatory for activation by calcium.