Study of permeation and blocker binding in TMEM16A calcium-activated chloride channels

Reyes, Juan Pablo; Huanosta-Gutiérrez, A.; Lopez-Rodriguez, Angélica; Martı́nez-Torres, Ataúlfo

doi:10.1080/19336950.2015.1027849

Cited by 7 publications

(10 citation statements)

References 19 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…We (this study) and others (Bradley et al ., ; Reyes et al ., ) showed that extracellular A9C only effectively blocked TMEM16A currents at positive V m . This is consistent with a model in which the inhibitory A9C binding site is accessible from the extracellular side and is situated within a region that spans the electric field of the membrane.…”

Section: Discussionmentioning

confidence: 96%

“…Recently, Reyes et al . () reported that A9C inhibited Xenopus laevis TMEM16A channels in a V m ‐dependent manner with a K i of ~90 μM at +80 mV. Bradley et al .…”

Section: Discussionmentioning

confidence: 96%

“…The δ i value of ~0.6 obtained from the Woodhull analysis suggests that the A9C molecule penetrates approximately 60% into the pore length (voltage field) to reach its inhibitory site. This finding is consistent with reported values of ~60 and ~54% for native Xenopus laevis CaCCs (Qu and Hartzell, ) and cloned TMEM16A channels (Reyes et al ., ) respectively. Cherian et al () reported a value of 57% for A9C block of cloned TMEM16B channels.…”

Section: Discussionmentioning

confidence: 96%

“…In this study, the potency of A9C block (IC 50 ) was quantified only at a single positive V m and the effects on current kinetics assessed in the presence of a single concentration of A9C. Another recent study (Reyes et al ., ) determined the extent of channel block by extracellular A9C on cloned Xenopus laevis TMEM16A at various V m . However, the current kinetics at negative V m was not examined.…”

Section: Introductionmentioning

confidence: 99%

See 3 more Smart Citations

Mechanism of allosteric activation of TMEM16A/ANO1 channels by a commonly used chloride channel blocker

Adomaviciene

Rorsman

et al. 2016

British J Pharmacology

View full text Add to dashboard Cite

Background and PurposeCalcium‐activated chloride channels (CaCCs) play varied physiological roles and constitute potential therapeutic targets for conditions such as asthma and hypertension. TMEM16A encodes a CaCC. CaCC pharmacology is restricted to compounds with relatively low potency and poorly defined selectivity. Anthracene‐9‐carboxylic acid (A9C), an inhibitor of various chloride channel types, exhibits complex effects on native CaCCs and cloned TMEM16A channels providing both activation and inhibition. The mechanisms underlying these effects are not fully defined.Experimental ApproachPatch‐clamp electrophysiology in conjunction with concentration jump experiments was employed to define the mode of interaction of A9C with TMEM16A channels.Key ResultsIn the presence of high intracellular Ca2+, A9C inhibited TMEM16A currents in a voltage‐dependent manner by entering the channel from the outside. A9C activation, revealed in the presence of submaximal intracellular Ca2+ concentrations, was also voltage‐dependent. The electric distance of A9C inhibiting and activating binding site was ~0.6 in each case. Inhibition occurred according to an open‐channel block mechanism. Activation was due to a dramatic leftward shift in the steady‐state activation curve and slowed deactivation kinetics. Extracellular A9C competed with extracellular Cl−, suggesting that A9C binds deep in the channel's pore to exert both inhibiting and activating effects.Conclusions and ImplicationsA9C is an open TMEM16A channel blocker and gating modifier. These effects require A9C to bind to a region within the pore that is accessible from the extracellular side of the membrane. These data will aid the future drug design of compounds that selectively activate or inhibit TMEM16A channels.

show abstract

Section: Discussionmentioning

confidence: 96%

“…Recently, Reyes et al . () reported that A9C inhibited Xenopus laevis TMEM16A channels in a V m ‐dependent manner with a K i of ~90 μM at +80 mV. Bradley et al .…”

Section: Discussionmentioning

confidence: 96%

Section: Discussionmentioning

confidence: 96%

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

Mechanism of allosteric activation of TMEM16A/ANO1 channels by a commonly used chloride channel blocker

Adomaviciene

Rorsman

et al. 2016

British J Pharmacology

View full text Add to dashboard Cite

show abstract

“…; Reyes et al . ) and residues near the top of the cleft have been identified as forming the vestibule and contributing to ionic selectivity (residues G628–M532 and I636–Q637; Yu et al . ) shown in red and residues R515, K603, R621 and R788 (Peters et al .…”

Section: Discussionmentioning

confidence: 99%

Gating modes of calcium‐activated chloride channels TMEM16A and TMEM16B

Cruz-Rangel

Jesús-Pérez

Contreras-Vite

et al. 2015

The Journal of Physiology

View full text Add to dashboard Cite

Key pointsr Calcium-activated chloride channels TMEM16A and TMEM16B support important physiological processes such as fast block of polyspermy, fluid secretion, control of blood pressure and sensory transduction.r Given the physiological importance of TMEM16 channels, it is important to study how incoming stimuli activate these channels. Here we study how channels open and close and how the process of gating is regulated.r We show that TMEM16A and TMEM16B display fast and slow gating. These gating modes are regulated by voltage and external chloride.r Dual gating explains the complex time course of the anion current. r Residues within the first intracellular loop of the channel influence the slow gating mode. r Dual gating is an intrinsic property observed in endogenous calcium-activated chloride channels and could be relevant to physiological processes that require sustained chloride ion movement.Abstract TMEM16A and TMEM16B are molecular components of the physiologically relevant calcium-activated chloride channels (CaCCs) present in many tissues. Their gating is dictated by membrane voltage (V m ), intracellular calcium concentrations ([Ca 2+ ] i ) and external permeant anions. As a consequence, the chloride current (I Cl ) kinetics is complex. For example, TMEM16A I Cl activates slowly with a non-mono-exponential time course while TMEM16B I Cl activates rapidly following a mono-exponential behaviour. To understand the underlying mechanism responsible for the complex activation kinetics, we recorded I Cl from HEK-293 cells transiently transfected with either TMEM16A or TMEM16B as well as from mouse parotid acinar cells. Two distinct V m -dependent gating modes were uncovered: a fast-mode on the millisecond time scale followed by a slow mode on the second time scale. Using long (20 s) depolarizing pulses both gating modes were activated, and a slowly rising I Cl was recorded in whole-cell and inside-out patches. The amplitude of I Cl at the end of the long pulse nearly doubled and was blocked by 100 μM tannic acid. The slow gating mode was strongly reduced by decreasing the [Cl − ] o from 140 to 30 mM and by altering the sequence of the first intracellular loop. Mutating 480 RSQ 482 to AVK in the first intracellular loop of TMEM16B nearly abolished slow gating, but, mutating 448 AVK 451 to RSQ in TMEM16A has little effect. Deleting 448 EAVK 451 residues in TMEM16A reduced slow gating. We conclude that TMEM16 CaCCs have intrinsic V m -and Cl − -sensitive dual gating that elicits complex I Cl kinetics.

show abstract

Function and Regulation of the Calcium-Activated Chloride Channel Anoctamin 1 (TMEM16A)

Arreola

Pérez‐Cornejo

Segura-Covarrubias

et al. 2022

Handbook of Experimental Pharmacology

View full text Add to dashboard Cite

Study of permeation and blocker binding in TMEM16A calcium-activated chloride channels

Cited by 7 publications

References 19 publications

Mechanism of allosteric activation of TMEM16A/ANO1 channels by a commonly used chloride channel blocker

Mechanism of allosteric activation of TMEM16A/ANO1 channels by a commonly used chloride channel blocker

Gating modes of calcium‐activated chloride channels TMEM16A and TMEM16B

Function and Regulation of the Calcium-Activated Chloride Channel Anoctamin 1 (TMEM16A)

Contact Info

Product

Resources

About