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Lovastatin blocks Kv1.3 channel in human T cells: a new mechanism to explain its immunomodulatory properties.

Zhao N, Dong Q, Qian C, Li S, Wu QF, Ding D, Li J, Wang BB, Guo KF, Xie JJ, Cheng X, Liao YH, Du YM - Sci Rep (2015)

Bottom Line: However, 30 μM Lovastatin had no apparent effect on KCa current in human T cells.At last, Mevalonate application only partially reversed the inhibition of Lovastatin on IL-2 secretion, and the siRNA against Kv1.3 also partially reduced this inhibitory effect of Lovastatin.In conclusion, Lovastatin can exert immunodulatory properties through the new mechanism of blocking Kv1.3 channel.

View Article: PubMed Central - PubMed

Affiliation: Research Center of Ion Channelopathy, Institute of Cardiology, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan 430022, China.

ABSTRACT
Lovastatin is a member of Statins, which are beneficial in a lot of immunologic cardiovascular diseases and T cell-mediated autoimmune diseases. Kv1.3 channel plays important roles in the activation and proliferation of T cells, and have become attractive target for immune-related disorders. The present study was designed to examine the block effect of Lovastatin on Kv1.3 channel in human T cells, and to clarify its new immunomodulatory mechanism. We found that Lovastatin inhibited Kv1.3 currents in a concentration- and voltage-dependent manner, and the IC50 for peak, end of the pulse was 39.81 ± 5.11, 6.92 ± 0.95 μM, respectively. Lovastatin also accelerated the decay rate of current inactivation and negatively shifted the steady-state inactivation curves concentration-dependently, without affecting the activation curve. However, 30 μM Lovastatin had no apparent effect on KCa current in human T cells. Furthermore, Lovastatin inhibited Ca(2+) influx, T cell proliferation as well as IL-2 production. The activities of NFAT1 and NF-κB p65/50 were down-regulated by Lovastatin, too. At last, Mevalonate application only partially reversed the inhibition of Lovastatin on IL-2 secretion, and the siRNA against Kv1.3 also partially reduced this inhibitory effect of Lovastatin. In conclusion, Lovastatin can exert immunodulatory properties through the new mechanism of blocking Kv1.3 channel.

No MeSH data available.


Related in: MedlinePlus

Blocking kinetics of Lovastatin on Kv1.3 channel.(A) The summarized current density-voltage relationship for the peak Kv1.3 currents in the absence (open square) and presence (filled square) of 30 μM Lovastatin. Kv1.3 currents were elicited by the same protocol as in Fig. 1A–C. (B) The summarized current density-voltage relationship for the end of pulse Kv1.3 currents under control (open square) and in the presence (filled square) of 30 μM Lovastatin. (C) The inhibition% of the peak Kv1.3 currents (open square) and currents at the end of pulse (filled square) were plotted with the test voltages. The dashed line showed the fitted activation curve of Kv1.3 currents at control. (D) Superimposed current traces recorded before and after a pulse-free period of incubation with Lovastatin. Currents through Kv1.3 channel expressed in HEK 293 were elicited by a 250 ms depolarizing to + 40 mV. Lovastatin (30 μM) was applied to the bath while the membrane potential was held at −80 mV. After an interval of 8 min, consecutive 250 ms pulses were applied every 10 s. The numbers 1 to 16 refers to pulses 1 to 16. (E) The activation curves in the absence and presence of 30 μM Lovastatin were fitted with Boltzman equation. G value was defined as I/(V–Erev), where I was peak amplitude, V was corresponding test voltage, and Erev was the reversal potential (−90 mV) of Kv1.3 channel. (F) The steady-state inactivation curves under control and in the presence of 10, 30 μM Lovastatin. The data were obtained from the normalized currents at + 40 mV, following a 30 s pre-pulse potentials from −80 mV to 0 mV, and fitted with the Boltzman equation to acquire the V1/2 value and κ. (G) Plot of Exp (∆V/κ) value against the Lovastatin concentration. The potential corresponding to half-inactivation voltage V1/2 and slope factor κ were acquired from the curves in Fig. 2F. (H) The time constants of the Kv1.3 currents decay phase at + 40 mV were acquired with mono-exponential equation and plotted against Lovastatin concentration. (*P < 0.05, **P < 0.01, ***P < 0.001 vs. control).
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f2: Blocking kinetics of Lovastatin on Kv1.3 channel.(A) The summarized current density-voltage relationship for the peak Kv1.3 currents in the absence (open square) and presence (filled square) of 30 μM Lovastatin. Kv1.3 currents were elicited by the same protocol as in Fig. 1A–C. (B) The summarized current density-voltage relationship for the end of pulse Kv1.3 currents under control (open square) and in the presence (filled square) of 30 μM Lovastatin. (C) The inhibition% of the peak Kv1.3 currents (open square) and currents at the end of pulse (filled square) were plotted with the test voltages. The dashed line showed the fitted activation curve of Kv1.3 currents at control. (D) Superimposed current traces recorded before and after a pulse-free period of incubation with Lovastatin. Currents through Kv1.3 channel expressed in HEK 293 were elicited by a 250 ms depolarizing to + 40 mV. Lovastatin (30 μM) was applied to the bath while the membrane potential was held at −80 mV. After an interval of 8 min, consecutive 250 ms pulses were applied every 10 s. The numbers 1 to 16 refers to pulses 1 to 16. (E) The activation curves in the absence and presence of 30 μM Lovastatin were fitted with Boltzman equation. G value was defined as I/(V–Erev), where I was peak amplitude, V was corresponding test voltage, and Erev was the reversal potential (−90 mV) of Kv1.3 channel. (F) The steady-state inactivation curves under control and in the presence of 10, 30 μM Lovastatin. The data were obtained from the normalized currents at + 40 mV, following a 30 s pre-pulse potentials from −80 mV to 0 mV, and fitted with the Boltzman equation to acquire the V1/2 value and κ. (G) Plot of Exp (∆V/κ) value against the Lovastatin concentration. The potential corresponding to half-inactivation voltage V1/2 and slope factor κ were acquired from the curves in Fig. 2F. (H) The time constants of the Kv1.3 currents decay phase at + 40 mV were acquired with mono-exponential equation and plotted against Lovastatin concentration. (*P < 0.05, **P < 0.01, ***P < 0.001 vs. control).

Mentions: Next, we observed the voltage-dependent block effect of Lovastatin on Kv1.3 channel. The current density-voltage relationship curves of the peak and the current end of the pulse, before and after 30 μM Lovastatin application, were shown in Fig. 2A,B, respectively. Lovastatin at 30 μM inhibited the peak and the pulse end current apparently above −40 mV when Kv1.3 channel was open. Then, we calculated the inhibition% of 30 μM Lovastatin on the peak and the pulse end current, which was plotted as a function of the test potentials. The activation curve was present in Fig. 3C, too. From –40 mV to 0 mV, the inhibition percentage of Lovastatin on peak and pulse end current increased sharply from 8.7% and 11.0% to 36.8% and 71.1%, respectively. This voltage range was consistent with the voltage for Kv1.3 channel opening. The inhibition increased to a plateau between +10 mV and +60 mV when the channel was fully activated. This blocking character suggested that Lovastatin may bind to the open state of Kv1.3 channel.


Lovastatin blocks Kv1.3 channel in human T cells: a new mechanism to explain its immunomodulatory properties.

Zhao N, Dong Q, Qian C, Li S, Wu QF, Ding D, Li J, Wang BB, Guo KF, Xie JJ, Cheng X, Liao YH, Du YM - Sci Rep (2015)

Blocking kinetics of Lovastatin on Kv1.3 channel.(A) The summarized current density-voltage relationship for the peak Kv1.3 currents in the absence (open square) and presence (filled square) of 30 μM Lovastatin. Kv1.3 currents were elicited by the same protocol as in Fig. 1A–C. (B) The summarized current density-voltage relationship for the end of pulse Kv1.3 currents under control (open square) and in the presence (filled square) of 30 μM Lovastatin. (C) The inhibition% of the peak Kv1.3 currents (open square) and currents at the end of pulse (filled square) were plotted with the test voltages. The dashed line showed the fitted activation curve of Kv1.3 currents at control. (D) Superimposed current traces recorded before and after a pulse-free period of incubation with Lovastatin. Currents through Kv1.3 channel expressed in HEK 293 were elicited by a 250 ms depolarizing to + 40 mV. Lovastatin (30 μM) was applied to the bath while the membrane potential was held at −80 mV. After an interval of 8 min, consecutive 250 ms pulses were applied every 10 s. The numbers 1 to 16 refers to pulses 1 to 16. (E) The activation curves in the absence and presence of 30 μM Lovastatin were fitted with Boltzman equation. G value was defined as I/(V–Erev), where I was peak amplitude, V was corresponding test voltage, and Erev was the reversal potential (−90 mV) of Kv1.3 channel. (F) The steady-state inactivation curves under control and in the presence of 10, 30 μM Lovastatin. The data were obtained from the normalized currents at + 40 mV, following a 30 s pre-pulse potentials from −80 mV to 0 mV, and fitted with the Boltzman equation to acquire the V1/2 value and κ. (G) Plot of Exp (∆V/κ) value against the Lovastatin concentration. The potential corresponding to half-inactivation voltage V1/2 and slope factor κ were acquired from the curves in Fig. 2F. (H) The time constants of the Kv1.3 currents decay phase at + 40 mV were acquired with mono-exponential equation and plotted against Lovastatin concentration. (*P < 0.05, **P < 0.01, ***P < 0.001 vs. control).
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Related In: Results  -  Collection

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Show All Figures
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f2: Blocking kinetics of Lovastatin on Kv1.3 channel.(A) The summarized current density-voltage relationship for the peak Kv1.3 currents in the absence (open square) and presence (filled square) of 30 μM Lovastatin. Kv1.3 currents were elicited by the same protocol as in Fig. 1A–C. (B) The summarized current density-voltage relationship for the end of pulse Kv1.3 currents under control (open square) and in the presence (filled square) of 30 μM Lovastatin. (C) The inhibition% of the peak Kv1.3 currents (open square) and currents at the end of pulse (filled square) were plotted with the test voltages. The dashed line showed the fitted activation curve of Kv1.3 currents at control. (D) Superimposed current traces recorded before and after a pulse-free period of incubation with Lovastatin. Currents through Kv1.3 channel expressed in HEK 293 were elicited by a 250 ms depolarizing to + 40 mV. Lovastatin (30 μM) was applied to the bath while the membrane potential was held at −80 mV. After an interval of 8 min, consecutive 250 ms pulses were applied every 10 s. The numbers 1 to 16 refers to pulses 1 to 16. (E) The activation curves in the absence and presence of 30 μM Lovastatin were fitted with Boltzman equation. G value was defined as I/(V–Erev), where I was peak amplitude, V was corresponding test voltage, and Erev was the reversal potential (−90 mV) of Kv1.3 channel. (F) The steady-state inactivation curves under control and in the presence of 10, 30 μM Lovastatin. The data were obtained from the normalized currents at + 40 mV, following a 30 s pre-pulse potentials from −80 mV to 0 mV, and fitted with the Boltzman equation to acquire the V1/2 value and κ. (G) Plot of Exp (∆V/κ) value against the Lovastatin concentration. The potential corresponding to half-inactivation voltage V1/2 and slope factor κ were acquired from the curves in Fig. 2F. (H) The time constants of the Kv1.3 currents decay phase at + 40 mV were acquired with mono-exponential equation and plotted against Lovastatin concentration. (*P < 0.05, **P < 0.01, ***P < 0.001 vs. control).
Mentions: Next, we observed the voltage-dependent block effect of Lovastatin on Kv1.3 channel. The current density-voltage relationship curves of the peak and the current end of the pulse, before and after 30 μM Lovastatin application, were shown in Fig. 2A,B, respectively. Lovastatin at 30 μM inhibited the peak and the pulse end current apparently above −40 mV when Kv1.3 channel was open. Then, we calculated the inhibition% of 30 μM Lovastatin on the peak and the pulse end current, which was plotted as a function of the test potentials. The activation curve was present in Fig. 3C, too. From –40 mV to 0 mV, the inhibition percentage of Lovastatin on peak and pulse end current increased sharply from 8.7% and 11.0% to 36.8% and 71.1%, respectively. This voltage range was consistent with the voltage for Kv1.3 channel opening. The inhibition increased to a plateau between +10 mV and +60 mV when the channel was fully activated. This blocking character suggested that Lovastatin may bind to the open state of Kv1.3 channel.

Bottom Line: However, 30 μM Lovastatin had no apparent effect on KCa current in human T cells.At last, Mevalonate application only partially reversed the inhibition of Lovastatin on IL-2 secretion, and the siRNA against Kv1.3 also partially reduced this inhibitory effect of Lovastatin.In conclusion, Lovastatin can exert immunodulatory properties through the new mechanism of blocking Kv1.3 channel.

View Article: PubMed Central - PubMed

Affiliation: Research Center of Ion Channelopathy, Institute of Cardiology, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan 430022, China.

ABSTRACT
Lovastatin is a member of Statins, which are beneficial in a lot of immunologic cardiovascular diseases and T cell-mediated autoimmune diseases. Kv1.3 channel plays important roles in the activation and proliferation of T cells, and have become attractive target for immune-related disorders. The present study was designed to examine the block effect of Lovastatin on Kv1.3 channel in human T cells, and to clarify its new immunomodulatory mechanism. We found that Lovastatin inhibited Kv1.3 currents in a concentration- and voltage-dependent manner, and the IC50 for peak, end of the pulse was 39.81 ± 5.11, 6.92 ± 0.95 μM, respectively. Lovastatin also accelerated the decay rate of current inactivation and negatively shifted the steady-state inactivation curves concentration-dependently, without affecting the activation curve. However, 30 μM Lovastatin had no apparent effect on KCa current in human T cells. Furthermore, Lovastatin inhibited Ca(2+) influx, T cell proliferation as well as IL-2 production. The activities of NFAT1 and NF-κB p65/50 were down-regulated by Lovastatin, too. At last, Mevalonate application only partially reversed the inhibition of Lovastatin on IL-2 secretion, and the siRNA against Kv1.3 also partially reduced this inhibitory effect of Lovastatin. In conclusion, Lovastatin can exert immunodulatory properties through the new mechanism of blocking Kv1.3 channel.

No MeSH data available.


Related in: MedlinePlus