[KCNE2 modulates the function of Kv4.3 channel].
OBJECTIVE
To understand the role of KCNE2 in functional regulation of Kv4.3, the major alpha subunit of transient outward current (I(to)) in human heart.


METHODS
The cDNAs of Kv4.3 or Kv4.3 plus KCNE2 were transfected into COS-7 cells and 24-36 h after the transfection, the channel proteins were expressed in the surface membrane of the cells and the channel currents were recorded with patch-clamp technique in whole-cell mode.


RESULTS
KCNE2 played an important role in modulating the channel function. The recorded current density was decreased in cells co-expressing KCNE2 and Kv4.3 to 152.96-/+33.71 pA/pF (n=16) as compared with Kv4.3-expressing cells with a mean current density of 375.13-/+112.87 pA/pF (n=11). At the recording voltage of 60 mV, KCNE2 increased the time to peak (TTP) of the current. TTP in only Kv4.3-expressing cells was 4.82-/+0.32 ms (n=11), significantly shorter than the TTP of 20.41-/+2.13 ms (n=16) in cells co-expressing Kv4.3 and KCNE2 (P<0.05). In the presence of KCNE2, the voltage-dependent inactivation of Kv4.3 showed a positive shift. The voltage of half maximum inactivation (V(0.5)) was decreased significantly from -53.62-/+1.24 mV (n=8) in Kv4.3 group to -46.58-/+1.6 mV (n=10) in KCNE2 co-expression group (P<0.05). KCNE2 accelerated the recovery of the channel from inactivation, reducing the recovery time constant (tau) from 193.43-/+17.98 ms to 137.71-/+18.29 ms.


CONCLUSIONS
KCNE2 might serve as an important beta subunit and play a role in the regulation of I(to) function in human heart.
Liu
Jie
J
Department of Pathophysiology, Southern Medical University, Guangzhou 510515, China. jieliu@ fimmu.com
Deng
Jian-xin
JX
Pan
Bing-xing
BX
Huang
Qiao-bing
QB
D000818:Animals; D019556:COS Cells; D002522:Chlorocebus aethiops; D006801:Humans; D051605:Kv Channel-Interacting Proteins / Q000235:genetics / Q000378:metabolism; D008564:Membrane Potentials / Q000502:physiology; D018408:Patch-Clamp Techniques; D024642:Potassium Channels, Voltage-Gated / Q000235:genetics / Q000378:metabolism / Q000502:physiology*; D051672:Shal Potassium Channels / Q000235:genetics / Q000378:metabolism / Q000502:physiology*; D014162:Transfection
C489619:KCNE2 protein, human; D051605:Kv Channel-Interacting Proteins; D024642:Potassium Channels, Voltage-Gated; D051672:Shal Potassium Channels