Abstract
Calmodulin (CaM), a Ca2+-sensing protein, is constitutively bound to IQ domains of the C termini of human Kv7 (hKv7, KCNQ) channels to mediate Ca2+-dependent reduction of Kv7 currents. However, the mechanism remains unclear. We report thatCaMbinds to two isoforms of the hKv7.4 channel in a Ca2+- independent manner but that only the long isoform (hKv7.4a) is regulated by Ca2+/CaM. Ca2+/CaM mediate reduction of the hKv7.4a channel by decreasing the channel open probability and altering activation kinetics. We took advantage of a known missense mutation (G321S) that has been linked to progressive hearing loss to further examine the inhibitory effects of Ca2+/CaM on the Kv7.4 channel. Using multidisciplinary techniques, we demonstrate that the G321S mutation may destabilize CaM binding, leading to a decrease in the inhibitory effects of Ca2+on the channels. Our study utilizes an expression system to dissect the biophysical properties of the WT and mutant Kv7.4 channels. This report provides mechanistic insights into the critical roles of Ca2+/CaM regulation of the Kv7.4 channel under physiological and pathological conditions.
| Original language | English (US) |
|---|---|
| Pages (from-to) | 2499-2509 |
| Number of pages | 11 |
| Journal | Journal of Biological Chemistry |
| Volume | 291 |
| Issue number | 5 |
| DOIs | |
| State | Published - Jan 29 2016 |
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ASJC Scopus subject areas
- Biochemistry
- Cell Biology
- Molecular Biology
Cite this
Mechanisms of calmodulin regulation of different isoforms of Kv7.4 K+ channels. / Sihn, Choong Ryoul; Kim, Hyo Jeong; Woltz, Ryan L.; Yarov-Yarovoy, Vladimir; Yang, Pei Chi; Xu, Jun; Clancy, Colleen E.; Zhang, Xiao Dong; Chiamvimonvat, Nipavan; Yamoah, Ebenezer N.
In: Journal of Biological Chemistry, Vol. 291, No. 5, 29.01.2016, p. 2499-2509.Research output: Contribution to journal › Article
}
TY - JOUR
T1 - Mechanisms of calmodulin regulation of different isoforms of Kv7.4 K+ channels
AU - Sihn, Choong Ryoul
AU - Kim, Hyo Jeong
AU - Woltz, Ryan L.
AU - Yarov-Yarovoy, Vladimir
AU - Yang, Pei Chi
AU - Xu, Jun
AU - Clancy, Colleen E.
AU - Zhang, Xiao Dong
AU - Chiamvimonvat, Nipavan
AU - Yamoah, Ebenezer N.
PY - 2016/1/29
Y1 - 2016/1/29
N2 - Calmodulin (CaM), a Ca2+-sensing protein, is constitutively bound to IQ domains of the C termini of human Kv7 (hKv7, KCNQ) channels to mediate Ca2+-dependent reduction of Kv7 currents. However, the mechanism remains unclear. We report thatCaMbinds to two isoforms of the hKv7.4 channel in a Ca2+- independent manner but that only the long isoform (hKv7.4a) is regulated by Ca2+/CaM. Ca2+/CaM mediate reduction of the hKv7.4a channel by decreasing the channel open probability and altering activation kinetics. We took advantage of a known missense mutation (G321S) that has been linked to progressive hearing loss to further examine the inhibitory effects of Ca2+/CaM on the Kv7.4 channel. Using multidisciplinary techniques, we demonstrate that the G321S mutation may destabilize CaM binding, leading to a decrease in the inhibitory effects of Ca2+on the channels. Our study utilizes an expression system to dissect the biophysical properties of the WT and mutant Kv7.4 channels. This report provides mechanistic insights into the critical roles of Ca2+/CaM regulation of the Kv7.4 channel under physiological and pathological conditions.
AB - Calmodulin (CaM), a Ca2+-sensing protein, is constitutively bound to IQ domains of the C termini of human Kv7 (hKv7, KCNQ) channels to mediate Ca2+-dependent reduction of Kv7 currents. However, the mechanism remains unclear. We report thatCaMbinds to two isoforms of the hKv7.4 channel in a Ca2+- independent manner but that only the long isoform (hKv7.4a) is regulated by Ca2+/CaM. Ca2+/CaM mediate reduction of the hKv7.4a channel by decreasing the channel open probability and altering activation kinetics. We took advantage of a known missense mutation (G321S) that has been linked to progressive hearing loss to further examine the inhibitory effects of Ca2+/CaM on the Kv7.4 channel. Using multidisciplinary techniques, we demonstrate that the G321S mutation may destabilize CaM binding, leading to a decrease in the inhibitory effects of Ca2+on the channels. Our study utilizes an expression system to dissect the biophysical properties of the WT and mutant Kv7.4 channels. This report provides mechanistic insights into the critical roles of Ca2+/CaM regulation of the Kv7.4 channel under physiological and pathological conditions.
UR - http://www.scopus.com/inward/record.url?scp=84956760942&partnerID=8YFLogxK
UR - http://www.scopus.com/inward/citedby.url?scp=84956760942&partnerID=8YFLogxK
U2 - 10.1074/jbc.M115.668236
DO - 10.1074/jbc.M115.668236
M3 - Article
C2 - 26515070
AN - SCOPUS:84956760942
VL - 291
SP - 2499
EP - 2509
JO - Journal of Biological Chemistry
JF - Journal of Biological Chemistry
SN - 0021-9258
IS - 5
ER -