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Modulation of the slow/common gating of CLC channels by intracellular cadmium.

Yu Y, Tsai MF, Yu WP, Chen TY - J. Gen. Physiol. (2015)

Bottom Line: Here, we found that intracellularly applied Cd(2+) reduces the current of CLC-0 because of its inhibition on the slow gating.Our experimental results suggest that mutations of the corresponding residues in CLC-0 change the subunit interaction and alter the slow gating of CLC-0.The effect of these mutations on modulations of slow gating of CLC channels by intracellular Cd(2+) likely depends on their alteration of subunit interactions.

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Affiliation: Center for Neuroscience and Department of Neurology, University of California, Davis, Davis, CA 95618 Center for Neuroscience and Department of Neurology, University of California, Davis, Davis, CA 95618.

No MeSH data available.


Intracellular Cd2+ inhibition on WT CLC-0 and the C212S mutant. (A) Original recording traces of WT CLC-0 in various intracellular [Cd2+]. The current relaxations at those hyperpolarized voltages are caused by voltage-dependent closure of the fast gate. (B) Normalized steady-state current of WT CLC-0 in different intracellular [Cd2+]: 0 (black), 30 µM (red), 300 µM (green), and 1 mM (purple). The initial tail currents after different test voltages in various [Cd2+] were all normalized to the maximal initial tail current in 0 [Cd2+]. (C) Fast-gate Po as a function of voltage in the presence of 0 (black), 30 µM (red), 100 µM (green), and 300 µM (blue) Cd2+, calculated by normalizing the initial tail current to the maximal tail current in the same [Cd2+]. (Inset) Current relaxation time constant of the recorded current as those shown in A, which is equal to the inverse of the sum of the opening and the closing rate of the fast gate. The colors representing various [Cd2+] are the same as those in the Po-V plot. (D) Comparing the effects of intracellular Cd2+ between WT CLC-0 and the C212S mutant. A test pulse of 60 mV followed by a tail voltage at −100 mV was given every 2 s to monitor the Cd2+ inhibition. Current was measured at the end of the tailed pulse when the current reached the steady state. Various [Cd2+] were applied at the time indicated by the arrows. Dash line represents zero-current level.
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fig2: Intracellular Cd2+ inhibition on WT CLC-0 and the C212S mutant. (A) Original recording traces of WT CLC-0 in various intracellular [Cd2+]. The current relaxations at those hyperpolarized voltages are caused by voltage-dependent closure of the fast gate. (B) Normalized steady-state current of WT CLC-0 in different intracellular [Cd2+]: 0 (black), 30 µM (red), 300 µM (green), and 1 mM (purple). The initial tail currents after different test voltages in various [Cd2+] were all normalized to the maximal initial tail current in 0 [Cd2+]. (C) Fast-gate Po as a function of voltage in the presence of 0 (black), 30 µM (red), 100 µM (green), and 300 µM (blue) Cd2+, calculated by normalizing the initial tail current to the maximal tail current in the same [Cd2+]. (Inset) Current relaxation time constant of the recorded current as those shown in A, which is equal to the inverse of the sum of the opening and the closing rate of the fast gate. The colors representing various [Cd2+] are the same as those in the Po-V plot. (D) Comparing the effects of intracellular Cd2+ between WT CLC-0 and the C212S mutant. A test pulse of 60 mV followed by a tail voltage at −100 mV was given every 2 s to monitor the Cd2+ inhibition. Current was measured at the end of the tailed pulse when the current reached the steady state. Various [Cd2+] were applied at the time indicated by the arrows. Dash line represents zero-current level.

Mentions: Similar to the extracellular effect of Zn2+ on CLC-0 (Chen, 1998), intracellular Cd2+ can also inhibit the channel, although much higher concentrations, at least tens of micromolars, are required to generate inhibition (Fig. 2, A and B). The Po-V curve and the kinetics of the fast gating of CLC-0 appear not to be affected by intracellular Cd2+ at a concentration range that significantly inhibits the channel (Fig. 2 C). Furthermore, the inhibition of the channel by Cd2+ is largely suppressed by the C212S mutation (Fig. 2 D), which prevents the slow gate of CLC-0 from closing (Lin et al., 1999). Collectively, these results suggest that intracellularly applied Cd2+ inhibits CLC-0 by modulating the slow gating.


Modulation of the slow/common gating of CLC channels by intracellular cadmium.

Yu Y, Tsai MF, Yu WP, Chen TY - J. Gen. Physiol. (2015)

Intracellular Cd2+ inhibition on WT CLC-0 and the C212S mutant. (A) Original recording traces of WT CLC-0 in various intracellular [Cd2+]. The current relaxations at those hyperpolarized voltages are caused by voltage-dependent closure of the fast gate. (B) Normalized steady-state current of WT CLC-0 in different intracellular [Cd2+]: 0 (black), 30 µM (red), 300 µM (green), and 1 mM (purple). The initial tail currents after different test voltages in various [Cd2+] were all normalized to the maximal initial tail current in 0 [Cd2+]. (C) Fast-gate Po as a function of voltage in the presence of 0 (black), 30 µM (red), 100 µM (green), and 300 µM (blue) Cd2+, calculated by normalizing the initial tail current to the maximal tail current in the same [Cd2+]. (Inset) Current relaxation time constant of the recorded current as those shown in A, which is equal to the inverse of the sum of the opening and the closing rate of the fast gate. The colors representing various [Cd2+] are the same as those in the Po-V plot. (D) Comparing the effects of intracellular Cd2+ between WT CLC-0 and the C212S mutant. A test pulse of 60 mV followed by a tail voltage at −100 mV was given every 2 s to monitor the Cd2+ inhibition. Current was measured at the end of the tailed pulse when the current reached the steady state. Various [Cd2+] were applied at the time indicated by the arrows. Dash line represents zero-current level.
© Copyright Policy - openaccess
Related In: Results  -  Collection

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fig2: Intracellular Cd2+ inhibition on WT CLC-0 and the C212S mutant. (A) Original recording traces of WT CLC-0 in various intracellular [Cd2+]. The current relaxations at those hyperpolarized voltages are caused by voltage-dependent closure of the fast gate. (B) Normalized steady-state current of WT CLC-0 in different intracellular [Cd2+]: 0 (black), 30 µM (red), 300 µM (green), and 1 mM (purple). The initial tail currents after different test voltages in various [Cd2+] were all normalized to the maximal initial tail current in 0 [Cd2+]. (C) Fast-gate Po as a function of voltage in the presence of 0 (black), 30 µM (red), 100 µM (green), and 300 µM (blue) Cd2+, calculated by normalizing the initial tail current to the maximal tail current in the same [Cd2+]. (Inset) Current relaxation time constant of the recorded current as those shown in A, which is equal to the inverse of the sum of the opening and the closing rate of the fast gate. The colors representing various [Cd2+] are the same as those in the Po-V plot. (D) Comparing the effects of intracellular Cd2+ between WT CLC-0 and the C212S mutant. A test pulse of 60 mV followed by a tail voltage at −100 mV was given every 2 s to monitor the Cd2+ inhibition. Current was measured at the end of the tailed pulse when the current reached the steady state. Various [Cd2+] were applied at the time indicated by the arrows. Dash line represents zero-current level.
Mentions: Similar to the extracellular effect of Zn2+ on CLC-0 (Chen, 1998), intracellular Cd2+ can also inhibit the channel, although much higher concentrations, at least tens of micromolars, are required to generate inhibition (Fig. 2, A and B). The Po-V curve and the kinetics of the fast gating of CLC-0 appear not to be affected by intracellular Cd2+ at a concentration range that significantly inhibits the channel (Fig. 2 C). Furthermore, the inhibition of the channel by Cd2+ is largely suppressed by the C212S mutation (Fig. 2 D), which prevents the slow gate of CLC-0 from closing (Lin et al., 1999). Collectively, these results suggest that intracellularly applied Cd2+ inhibits CLC-0 by modulating the slow gating.

Bottom Line: Here, we found that intracellularly applied Cd(2+) reduces the current of CLC-0 because of its inhibition on the slow gating.Our experimental results suggest that mutations of the corresponding residues in CLC-0 change the subunit interaction and alter the slow gating of CLC-0.The effect of these mutations on modulations of slow gating of CLC channels by intracellular Cd(2+) likely depends on their alteration of subunit interactions.

View Article: PubMed Central - HTML - PubMed

Affiliation: Center for Neuroscience and Department of Neurology, University of California, Davis, Davis, CA 95618 Center for Neuroscience and Department of Neurology, University of California, Davis, Davis, CA 95618.

No MeSH data available.