Page 35 - F. Cell biology

PCB77 changes the steady-state

current and τ values of the Kv1.3 channel

Jonghui Kim , Su-Hyun Jo 1,2
1

1 Interdisciplinary Graduate Program for BIT Medical Convergence, Kangwon National University, Chuncheon 200-701, Korea Department of
2

Physiology, School of Medicine, Kangwon National University, Chuncheon 200-701, Korea

ABSTRACT A B 1.8 con A B

3nM PCB77
1.2 con 10nM PCB77 1.2 [PCB77](µΜ) 1.2 [PCB77](µΜ)
0
0
30nM PCB77
Polychlorinated biphenyls (PCBs) are a family of 3nM PCB77 1.5 100nM PCB77 0.003 0.003
10nM PCB77
0.01
0.01
bicyclic chlorinated aromatic hydrocarbons. PCBs’ 1.0 30nM PCB77 1.2 1uM PCB77 1.0 0.03 1.0 0.03
10uM PCB77
100nM PCB77
0.1
0.1
0.8
0.8
unique chemical properties and the low cost of producing 0.6 1uM PCB77 0.9 0.8 2 0.6 2
10uM PCB77
10
10
PCBs have contributed to their extensive industrial use. Normalized peak current 0.4 Normalized steady-state current 0.6 Normalized peak current 0.6 Normalized steady-state current 0.4
Acute and long-term exposure to the compounds has 0.2 0.3 0.4 0.2

been known to causes diseases such as developmental 0.0 0.0 0.2 0.0

delays and motor dysfunction. The presence of PCBs in -0.2 -0.3 -40 -20 0 20 40 60 0.0 -40 -20 0 20 40 60 -60 -40 -20 0 20 40 60

-60
-60
the environment presents various toxic effects in vivo -60 -40 -20 0 20 40 60 Membrane Potential (mV) Membrane Potential (mV)

and in vitro, but the mechanism is not yet fully C Membrane Potential (mV) D C Membrane Potential (mV) D

understood. One immune-modulating mechanism is 1.2 con 1.8 con 1.2 [PCB77](µΜ) 1.2 [PCB77](µΜ)
0
0
3nM PCB77
3nM PCB77
0.003
0.003
achieved by the Kv1.3 voltage-dependent potassium 1.0 10nM PCB77 1.5 10nM PCB77 1.0 0.01 1.0 0.01
30nM PCB77
30nM PCB77
100nM PCB77
0.03
0.03
100nM PCB77
channel, which is expressed highly in lymphocytes 0.8 1uM PCB77 1.2 1uM PCB77 0.8 0.1 0.8 0.1
10uM PCB77
2
10uM PCB77
2
including effector memory T lymphocytes. Here we Normalized peak current 0.6 0.9 Normalized peak current 0.6 10 0.6 10
studied the effect Polychlorinated biphenyls (3,3′,4,4′- 0.4 Normalized steady-state current 0.6 0.4 Normalized steady-state current 0.4
0.2
tetrachlorobiphenyl, PCB77) on human Kv1.3 channels 0.0 0.3 0.2 0.2

expressed in Xenopus oocytes. When we exposed the -0.2 0.0 0.0 0.0

oocytes with PCB77 for 8 min and 15min, the steady -60 -40 -20 0 20 40 60 -0.3 -40 -20 0 20 40 60 -60 -40 -20 0 20 40 60 -60 -40 -20 0 20 40 60
-60

state current of Kv 1.3 channel increased significantly. In Membrane Potential (mV) Membrane Potential (mV) Membrane Potential (mV) Membrane Potential (mV)

addition, the τ values of the KV1.3 current trace was FIG 3. Effect of PCB77 on Kv1.3 channel currents. Current- FIG 4. Effect of PCB77 on Kv1.5 channel currents. Current-

increased 50% by 10 nM PCB77. These results suggest voltage (I-V) relationship of peak and steady-state currents in the absence voltage (I-V) relationship of peak and steady-state currents in the absence

that PCBs could affect the heart in a way that did not and presence of PCB77. Peak currents were measured at peak and steady- and presence of PCB77. Peak currents were measured at peak and steady-

block, a voltage-dependent potassium channel, kv1.3 state currents were measured at the end of depolarizing pulses. Peak and state currents were measured at the end of depolarizing pulses. Peak and

channel directly.These results suggest that PCB77 shows steady-state currents of +50 mV in controls were normalized to 1. steady-state currents of +50 mV in controls were normalized to 1.

physiological toxicity by increases the current of the Kv Symbols with error bars represent mean ± S.E.M. (n = 5~7). Plot of the Symbols with error bars represent mean ± S.E.M. (n = 5~7). Plot of the

1.3 channel. normalized tail current measured at its peak just after repolarization. The normalized tail current measured at its peak just after repolarization. The

peak amplitude of the tail current in the absence of the drug was set as peak amplitude of the tail current in the absence of the drug was set as

Keywords: Polychlorinated biphenyls, PCBs, 1.(A) Peak current by PCB77 for 8 min. (B) Plot of the normalized tail 1.(A) Peak current by PCB77 for 8 min. (B) Plot of the normalized tail
steady-state current by PCB77 for 8min. (c) Peak current by PCB77 for
steady-state current by PCB77 for 8min. (c) Peak current by PCB77 for
PCB77, Kv1.3 15 min. (d) steady-state current by PCB77 for 15min. 15 min. (d) steady-state current by PCB77 for 15min.

A B

A 6000 6000
Normalized tail current
1.0 control
1.0
3nM PCB77 4500 4500

10nM PCB77

0.8
0.8 Normalized current 3000 Control Normalized current 3000 Control

3 nM PCB77

10 nM PCB77
0.6
0.6 1500 3 nM PCB77 1500 10 nM PCB77

0 0
0.4
0.4
0 20 40 60 80 100 0 400 800 1200 1600
C * Time (ms) D * Time (ms)

0.2 15 * * * * * *
0.2
FIG 1: Chemical structure of 3,3’,4,4’- 750

tetrachlorobiphenyl, PCB 77. The Molecular Weight of 0.0 12 600
0.0

PCB 77 is 291.98 g/mol and the Molecular Formula is C12H6Cl4. 9 450

20 40 60 80
-80 -60 -40 -20
PCB77 is Bicyclic chlorinated aromatic hydrocarbons. -80 -60 -40 -20 0 0 20 40 60 80 of activation (ms) 6 of activation (ms) 300

A +50 Membrane Potential (mV) τ 3 τ 150

0

-60mV B 1.0 0 0.003 0.01 1 10 0 0 0.003 0.01 1 10

-50 control [PCB77] (µM) [PCB77] (µM)
3nM PCB77
B C 0.8 10nM PCB77 FIG 6. Time courses of Kv1.3 channel current inhibition by

(a) (a) PCB77. Current trace was obtained by normalized data to its peak and

0.6 steady state value. Representative normalized current traces of the (A)

activation and (B) inactivation phase in the absence of PCB77 and in the

0.4
Normalized tail current presence of 3 nM, 10nM. Time constant value of (C) activation and (D)

(b) Control (b) Control inactivation current processes in the absence of PCB77 and in the
presence of 3 nM, 10nM. Columns with error bars represent mean ± SEM
0.2

(*P < 0.05).

0.0 SUMMARY

10nM PCB77 for 8min 10nM PCB77 for 8min

(c) (c) -80 -60 -40 -20 0 1. PCB 77 is one of the PCB congeners that have been known as

Membrane Potential (mV) organic pollutants (POPs), cause delayed development and

motor dysfunction.

FIG 5. Effect of PCB77 on steady-state activation and in 2. Treatment of PCB77 for 8min and 15min did not change peak

10nM PCB77 for 15min 10nM PCB77 for 15min activation of Kv1.3 channels. Steady-state activation curves currents of Kv1.3 channel current.

and inactivation curves obtained by normalizing to tail 3. Exposure PCB 77 for 8min and 15min increased steady-state
Figure 2. Kv1.3 channel and Kv 1.5 channel currents amplitude when depolarized to +50 mV and by fitting data with currents of Kv1.3 channel.

by PCB77. (A)Voltage pulses from -50 mV to +50 mV of 1 s 4. In addition, the τ values of the KV1.3 current trace was

duration with 10 mV increments every 10 s from a holding a Boltzmann equation. Symbols with error bars represent increased 50% by 10 nM PCB77.

potential of -60 mV. (B) Superimposed current traces for mean±standard error of the mean (n=5). (A,B) Exposure 3nM

exposure to PCB 77 at Kv 1.3 channel. (C) Superimposed and 10nM PCB77 5. These results suggest that PCBs could affect the heart in a

current traces for exposure to PCB 77 at Kv 1.5 channel. (a) way that did not block, a voltage-dependent potassium channel,

Superimposed current traces for not exposed to PCB77. (b) kv1.5 channel directly.

exposure 10nM PCB77 for 8min. (c) exposure 10 nM PCB77 for 6. These results suggest that PCB77 shows physiological and

15min Immune toxicity by increases the current of the Kv 1.3 channel.