Expression of a calmodulin-binding KCNQ2 potassium channel fragment modulates neuronal M-current and membrane excitability

Mohammad Shahidullah, Lindsey Ciali Santarelli, Hua Wen, Irwin B. Levitan

Research output: Contribution to journalArticle

32 Citations (Scopus)

Abstract

KCNQ2 and KCNQ3 ion channel pore-forming subunits coassemble to form a heteromeric voltage-gated potassium channel that underlies the neuronal M-current. We and others showed that calmodulin (CaM) binds to specific sequence motifs in the C-terminal domain of KCNQ2 and KCNQ3. We also found that a fusion protein containing a KCNQ2 CaM-binding motif, coexpressed with KCNQ2 and KCNQ3, competes with the full-length KCNQ2 channel for CaM binding and thereby decreases KCNQ2/3 current density in heterologous cells. We have explored the importance of CaM binding for the generation of the native M-current and regulation of membrane excitability in rat hippocampal neurons in primary cell culture. M-current properties were studied in cultured neurons by using whole-cell patch clamp recording. The M-current density is lower in neurons expressing the CaM-binding motif fusion protein, as compared to control neurons transfected with vector alone. In contrast, no change in M-current density is observed in cells transfected with a mutant fusion protein that is unable to bind CaM. The CaM-binding fusion protein does not influence the rapidly inactivating A-current or the large conductance calcium-activated potassium channel-mediated fast spike afterhyperpolarization in neurons in which the M-current is suppressed. Furthermore, the CaM-binding fusion protein, but not the non-binding mutant, increases both the number of action potentials evoked by membrane depolarization and the size of the spike afterdepolarization. These results suggest that CaM binding regulates M-channel function and membrane excitability in the native neuronal environment.

Original languageEnglish (US)
Pages (from-to)16454-16459
Number of pages6
JournalProceedings of the National Academy of Sciences of the United States of America
Volume102
Issue number45
DOIs
StatePublished - Nov 8 2005
Externally publishedYes

Fingerprint

KCNQ2 Potassium Channel
Calmodulin
Membranes
Neurons
Calmodulin-Binding Proteins
Ion Channels
Large-Conductance Calcium-Activated Potassium Channels
Voltage-Gated Potassium Channels
Amino Acid Motifs
Primary Cell Culture
Mutant Proteins
Action Potentials

Keywords

  • A-current
  • Afterdepolarization
  • Afterhyperpolarization

ASJC Scopus subject areas

  • Genetics
  • General

Cite this

Expression of a calmodulin-binding KCNQ2 potassium channel fragment modulates neuronal M-current and membrane excitability. / Shahidullah, Mohammad; Santarelli, Lindsey Ciali; Wen, Hua; Levitan, Irwin B.

In: Proceedings of the National Academy of Sciences of the United States of America, Vol. 102, No. 45, 08.11.2005, p. 16454-16459.

Research output: Contribution to journalArticle

@article{d877b083ce3a4badb1013f1ed0bf8522,
title = "Expression of a calmodulin-binding KCNQ2 potassium channel fragment modulates neuronal M-current and membrane excitability",
abstract = "KCNQ2 and KCNQ3 ion channel pore-forming subunits coassemble to form a heteromeric voltage-gated potassium channel that underlies the neuronal M-current. We and others showed that calmodulin (CaM) binds to specific sequence motifs in the C-terminal domain of KCNQ2 and KCNQ3. We also found that a fusion protein containing a KCNQ2 CaM-binding motif, coexpressed with KCNQ2 and KCNQ3, competes with the full-length KCNQ2 channel for CaM binding and thereby decreases KCNQ2/3 current density in heterologous cells. We have explored the importance of CaM binding for the generation of the native M-current and regulation of membrane excitability in rat hippocampal neurons in primary cell culture. M-current properties were studied in cultured neurons by using whole-cell patch clamp recording. The M-current density is lower in neurons expressing the CaM-binding motif fusion protein, as compared to control neurons transfected with vector alone. In contrast, no change in M-current density is observed in cells transfected with a mutant fusion protein that is unable to bind CaM. The CaM-binding fusion protein does not influence the rapidly inactivating A-current or the large conductance calcium-activated potassium channel-mediated fast spike afterhyperpolarization in neurons in which the M-current is suppressed. Furthermore, the CaM-binding fusion protein, but not the non-binding mutant, increases both the number of action potentials evoked by membrane depolarization and the size of the spike afterdepolarization. These results suggest that CaM binding regulates M-channel function and membrane excitability in the native neuronal environment.",
keywords = "A-current, Afterdepolarization, Afterhyperpolarization",
author = "Mohammad Shahidullah and Santarelli, {Lindsey Ciali} and Hua Wen and Levitan, {Irwin B.}",
year = "2005",
month = "11",
day = "8",
doi = "10.1073/pnas.0503966102",
language = "English (US)",
volume = "102",
pages = "16454--16459",
journal = "Proceedings of the National Academy of Sciences of the United States of America",
issn = "0027-8424",
number = "45",

}

TY - JOUR

T1 - Expression of a calmodulin-binding KCNQ2 potassium channel fragment modulates neuronal M-current and membrane excitability

AU - Shahidullah, Mohammad

AU - Santarelli, Lindsey Ciali

AU - Wen, Hua

AU - Levitan, Irwin B.

PY - 2005/11/8

Y1 - 2005/11/8

N2 - KCNQ2 and KCNQ3 ion channel pore-forming subunits coassemble to form a heteromeric voltage-gated potassium channel that underlies the neuronal M-current. We and others showed that calmodulin (CaM) binds to specific sequence motifs in the C-terminal domain of KCNQ2 and KCNQ3. We also found that a fusion protein containing a KCNQ2 CaM-binding motif, coexpressed with KCNQ2 and KCNQ3, competes with the full-length KCNQ2 channel for CaM binding and thereby decreases KCNQ2/3 current density in heterologous cells. We have explored the importance of CaM binding for the generation of the native M-current and regulation of membrane excitability in rat hippocampal neurons in primary cell culture. M-current properties were studied in cultured neurons by using whole-cell patch clamp recording. The M-current density is lower in neurons expressing the CaM-binding motif fusion protein, as compared to control neurons transfected with vector alone. In contrast, no change in M-current density is observed in cells transfected with a mutant fusion protein that is unable to bind CaM. The CaM-binding fusion protein does not influence the rapidly inactivating A-current or the large conductance calcium-activated potassium channel-mediated fast spike afterhyperpolarization in neurons in which the M-current is suppressed. Furthermore, the CaM-binding fusion protein, but not the non-binding mutant, increases both the number of action potentials evoked by membrane depolarization and the size of the spike afterdepolarization. These results suggest that CaM binding regulates M-channel function and membrane excitability in the native neuronal environment.

AB - KCNQ2 and KCNQ3 ion channel pore-forming subunits coassemble to form a heteromeric voltage-gated potassium channel that underlies the neuronal M-current. We and others showed that calmodulin (CaM) binds to specific sequence motifs in the C-terminal domain of KCNQ2 and KCNQ3. We also found that a fusion protein containing a KCNQ2 CaM-binding motif, coexpressed with KCNQ2 and KCNQ3, competes with the full-length KCNQ2 channel for CaM binding and thereby decreases KCNQ2/3 current density in heterologous cells. We have explored the importance of CaM binding for the generation of the native M-current and regulation of membrane excitability in rat hippocampal neurons in primary cell culture. M-current properties were studied in cultured neurons by using whole-cell patch clamp recording. The M-current density is lower in neurons expressing the CaM-binding motif fusion protein, as compared to control neurons transfected with vector alone. In contrast, no change in M-current density is observed in cells transfected with a mutant fusion protein that is unable to bind CaM. The CaM-binding fusion protein does not influence the rapidly inactivating A-current or the large conductance calcium-activated potassium channel-mediated fast spike afterhyperpolarization in neurons in which the M-current is suppressed. Furthermore, the CaM-binding fusion protein, but not the non-binding mutant, increases both the number of action potentials evoked by membrane depolarization and the size of the spike afterdepolarization. These results suggest that CaM binding regulates M-channel function and membrane excitability in the native neuronal environment.

KW - A-current

KW - Afterdepolarization

KW - Afterhyperpolarization

UR - http://www.scopus.com/inward/record.url?scp=28044453940&partnerID=8YFLogxK

UR - http://www.scopus.com/inward/citedby.url?scp=28044453940&partnerID=8YFLogxK

U2 - 10.1073/pnas.0503966102

DO - 10.1073/pnas.0503966102

M3 - Article

VL - 102

SP - 16454

EP - 16459

JO - Proceedings of the National Academy of Sciences of the United States of America

JF - Proceedings of the National Academy of Sciences of the United States of America

SN - 0027-8424

IS - 45

ER -