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Murine Aortic Crush Injury: An Efficient In Vivo Model of Smooth Muscle Cell Proliferation and Endothelial Function
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Mitogenic modulation of Ca2+ -activated K+ channels in proliferating A7r5 vascular smooth muscle cells

Han Si1, Ivica Grgic, Willm-Thomas Heyken

  • 1Department of Internal Medicine-Nephrology, Philipps-Universität, Marburg 35033, Germany.

British Journal of Pharmacology
|June 14, 2006
PubMed

Insights

Modulation of calcium-activated potassium channels (K(Ca)) impacts vascular smooth muscle cell proliferation. Upregulation of intermediate-conductance K(Ca) (IK(Ca)/rK(Ca)3.1) via ERK signaling promotes cell growth, suggesting a therapeutic target.

Area of Science:

  • Molecular Biology
  • Cell Physiology
  • Cardiovascular Research

Background:

  • Calcium-activated potassium channels (K(Ca)) play a role in vascular smooth muscle cell (VSMC) proliferation.
  • Specific K(Ca) subtypes, IK(Ca)/rK(Ca)3.1 and BK(Ca)/rK(Ca)1.1, are expressed in VSMCs, but their roles in mitogenesis are not fully understood.
  • Understanding the signaling pathways regulating K(Ca) expression is crucial for targeting VSMC proliferation in cardiovascular diseases.

Purpose of the Study:

  • To investigate the signal transduction mechanisms controlling mitogen-induced changes in intermediate-conductance K(Ca) (IK(Ca)/rK(Ca)3.1) expression in VSMCs.
  • To determine the role of IK(Ca)/rK(Ca)3.1 and BK(Ca)/rK(Ca)1.1 in VSMC proliferation.
  • To explore the potential of IK(Ca)/rK(Ca)3.1 as a pharmacological target for cardiovascular diseases.

Main Methods:

  • Utilized A7r5 rat aortic VSMC cell line.
  • Employed patch-clamp electrophysiology, quantitative RT-PCR, immunoblotting, and siRNA to study K(Ca) expression and function.
  • Investigated signaling pathways including ERK1/2, p38-MAPK, JNK, PKC, CaMKII, and Src kinases.

Main Results:

  • Platelet-derived growth factor (PDGF) stimulation increased rK(Ca)3.1 transcript levels and IK(Ca) currents in a time-dependent manner.
  • Upregulation of rK(Ca)3.1 required ERK1/2 phosphorylation and Ca(2+) mobilization, but not other tested kinases.
  • BK(Ca)/rK(Ca)1.1 expression and function were decreased by PDGF, independently of ERK1/2 or Ca(2+) signaling.
  • siRNA-mediated knockdown of rK(Ca)3.1 abolished IK(Ca) currents and VSMC proliferation.
  • Mitogen-induced rK(Ca)3.1 upregulation is mediated by the Raf/MEK/ERK cascade in a Ca(2+)-dependent manner.

Conclusions:

  • Mitogen-induced VSMC proliferation is promoted by the upregulation of IK(Ca)/rK(Ca)3.1.
  • The ERK signaling pathway, dependent on Ca(2+) mobilization, mediates this upregulation.
  • IK(Ca)/rK(Ca)3.1 represents a potential pharmacological target for cardiovascular diseases involving abnormal VSMC proliferation.

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