Alternative splicing of Cav1.2 channel exons in smooth muscle cells of resistance-size arteries generates currents with unique electrophysiological properties

Xiaoyang Cheng, Judith Pachuau, Eva Blaskova, Maria Asuncion-Chin, Jianxi Liu, Alejandro Dopico, Jonathan Jaggar

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Abstract

Voltage-dependent calcium (Ca2+, CaV1.2) channels are the primary Ca2+ entry pathway in smooth muscle cells of resistance-size (myogenic) arteries, but their molecular identity remains unclear. Here we identified and quantified CaV1.2 α1-subunit splice variation in myocytes of rat resistance-size (100-200 μm diameter) cerebral arteries. Full-length clones containing either exon 1b or the recently identified exon 1c exhibited additional primary splice variation at exons 9*, 21/22, 31/32, and ± 33. Real-time PCR confirmed the findings from full-length clones and indicated that the major CaV1.2 variant contained exons 1c, 8, 21, and 32+33, with ∼57% containing 9*. Exon 9* was more prevalent in clones containing 1c (72%) than in those containing 1b (33%), suggesting exon-selective combinatorial splicing. To examine the functional significance of this splicing profile, membrane currents produced by each of the four exon 1b/c/ ± 9* variants were characterized following transfection in HEK293 cells. Exon 1c and 9* caused similar hyperpolarizing shifts in both current-voltage relationships and voltage-dependent activation of currents. Furthermore, exon 9* induced a hyperpolarizing shift only in the voltage-dependent activation of channels containing exon 1b, but not in those containing exon 1c. In contrast, exon 1b, 1c, or +9* did not alter voltage-dependent inactivation. In summary, we have identified the CaV1.2 α1-subunit splice variant population that is expressed in myocytes of resistance-size arteries and the unique electrophysiological properties of recombinant channels formed by exon 1 and 9* variation. The predominance of exon 1c and 9* in smooth muscle cell CaV1.2 channels causes a hyperpolarizing shift in the voltage sensitivity of currents toward the physiological arterial voltage range.

Original languageEnglish (US)
JournalAmerican Journal of Physiology - Heart and Circulatory Physiology
Volume297
Issue number2
DOIs
StatePublished - Aug 1 2009

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Alternative Splicing
Cell Size
Smooth Muscle Myocytes
Exons
Arteries
Clone Cells
Muscle Cells
Cerebral Arteries
HEK293 Cells
Transfection
Real-Time Polymerase Chain Reaction

All Science Journal Classification (ASJC) codes

  • Physiology
  • Cardiology and Cardiovascular Medicine
  • Physiology (medical)

Cite this

@article{38b2aa8957344c0b88256b51aa6546b3,
title = "Alternative splicing of Cav1.2 channel exons in smooth muscle cells of resistance-size arteries generates currents with unique electrophysiological properties",
abstract = "Voltage-dependent calcium (Ca2+, CaV1.2) channels are the primary Ca2+ entry pathway in smooth muscle cells of resistance-size (myogenic) arteries, but their molecular identity remains unclear. Here we identified and quantified CaV1.2 α1-subunit splice variation in myocytes of rat resistance-size (100-200 μm diameter) cerebral arteries. Full-length clones containing either exon 1b or the recently identified exon 1c exhibited additional primary splice variation at exons 9*, 21/22, 31/32, and ± 33. Real-time PCR confirmed the findings from full-length clones and indicated that the major CaV1.2 variant contained exons 1c, 8, 21, and 32+33, with ∼57{\%} containing 9*. Exon 9* was more prevalent in clones containing 1c (72{\%}) than in those containing 1b (33{\%}), suggesting exon-selective combinatorial splicing. To examine the functional significance of this splicing profile, membrane currents produced by each of the four exon 1b/c/ ± 9* variants were characterized following transfection in HEK293 cells. Exon 1c and 9* caused similar hyperpolarizing shifts in both current-voltage relationships and voltage-dependent activation of currents. Furthermore, exon 9* induced a hyperpolarizing shift only in the voltage-dependent activation of channels containing exon 1b, but not in those containing exon 1c. In contrast, exon 1b, 1c, or +9* did not alter voltage-dependent inactivation. In summary, we have identified the CaV1.2 α1-subunit splice variant population that is expressed in myocytes of resistance-size arteries and the unique electrophysiological properties of recombinant channels formed by exon 1 and 9* variation. The predominance of exon 1c and 9* in smooth muscle cell CaV1.2 channels causes a hyperpolarizing shift in the voltage sensitivity of currents toward the physiological arterial voltage range.",
author = "Xiaoyang Cheng and Judith Pachuau and Eva Blaskova and Maria Asuncion-Chin and Jianxi Liu and Alejandro Dopico and Jonathan Jaggar",
year = "2009",
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doi = "10.1152/ajpheart.00109.2009",
language = "English (US)",
volume = "297",
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TY - JOUR

T1 - Alternative splicing of Cav1.2 channel exons in smooth muscle cells of resistance-size arteries generates currents with unique electrophysiological properties

AU - Cheng, Xiaoyang

AU - Pachuau, Judith

AU - Blaskova, Eva

AU - Asuncion-Chin, Maria

AU - Liu, Jianxi

AU - Dopico, Alejandro

AU - Jaggar, Jonathan

PY - 2009/8/1

Y1 - 2009/8/1

N2 - Voltage-dependent calcium (Ca2+, CaV1.2) channels are the primary Ca2+ entry pathway in smooth muscle cells of resistance-size (myogenic) arteries, but their molecular identity remains unclear. Here we identified and quantified CaV1.2 α1-subunit splice variation in myocytes of rat resistance-size (100-200 μm diameter) cerebral arteries. Full-length clones containing either exon 1b or the recently identified exon 1c exhibited additional primary splice variation at exons 9*, 21/22, 31/32, and ± 33. Real-time PCR confirmed the findings from full-length clones and indicated that the major CaV1.2 variant contained exons 1c, 8, 21, and 32+33, with ∼57% containing 9*. Exon 9* was more prevalent in clones containing 1c (72%) than in those containing 1b (33%), suggesting exon-selective combinatorial splicing. To examine the functional significance of this splicing profile, membrane currents produced by each of the four exon 1b/c/ ± 9* variants were characterized following transfection in HEK293 cells. Exon 1c and 9* caused similar hyperpolarizing shifts in both current-voltage relationships and voltage-dependent activation of currents. Furthermore, exon 9* induced a hyperpolarizing shift only in the voltage-dependent activation of channels containing exon 1b, but not in those containing exon 1c. In contrast, exon 1b, 1c, or +9* did not alter voltage-dependent inactivation. In summary, we have identified the CaV1.2 α1-subunit splice variant population that is expressed in myocytes of resistance-size arteries and the unique electrophysiological properties of recombinant channels formed by exon 1 and 9* variation. The predominance of exon 1c and 9* in smooth muscle cell CaV1.2 channels causes a hyperpolarizing shift in the voltage sensitivity of currents toward the physiological arterial voltage range.

AB - Voltage-dependent calcium (Ca2+, CaV1.2) channels are the primary Ca2+ entry pathway in smooth muscle cells of resistance-size (myogenic) arteries, but their molecular identity remains unclear. Here we identified and quantified CaV1.2 α1-subunit splice variation in myocytes of rat resistance-size (100-200 μm diameter) cerebral arteries. Full-length clones containing either exon 1b or the recently identified exon 1c exhibited additional primary splice variation at exons 9*, 21/22, 31/32, and ± 33. Real-time PCR confirmed the findings from full-length clones and indicated that the major CaV1.2 variant contained exons 1c, 8, 21, and 32+33, with ∼57% containing 9*. Exon 9* was more prevalent in clones containing 1c (72%) than in those containing 1b (33%), suggesting exon-selective combinatorial splicing. To examine the functional significance of this splicing profile, membrane currents produced by each of the four exon 1b/c/ ± 9* variants were characterized following transfection in HEK293 cells. Exon 1c and 9* caused similar hyperpolarizing shifts in both current-voltage relationships and voltage-dependent activation of currents. Furthermore, exon 9* induced a hyperpolarizing shift only in the voltage-dependent activation of channels containing exon 1b, but not in those containing exon 1c. In contrast, exon 1b, 1c, or +9* did not alter voltage-dependent inactivation. In summary, we have identified the CaV1.2 α1-subunit splice variant population that is expressed in myocytes of resistance-size arteries and the unique electrophysiological properties of recombinant channels formed by exon 1 and 9* variation. The predominance of exon 1c and 9* in smooth muscle cell CaV1.2 channels causes a hyperpolarizing shift in the voltage sensitivity of currents toward the physiological arterial voltage range.

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U2 - 10.1152/ajpheart.00109.2009

DO - 10.1152/ajpheart.00109.2009

M3 - Article

VL - 297

JO - American Journal of Physiology

JF - American Journal of Physiology

SN - 0363-6135

IS - 2

ER -