Regulation by FK506 and rapamycin of Ca2+ release from the sarcoplasmic reticulum in vascular smooth muscle: the role of FK506 binding proteins and mTOR

D. MacMillan, J.G. McCarron

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22 Citations (Scopus)

Abstract

Background and purpose: The sarcoplasmic reticulum (SR), regulates the cytoplasmic Ca2+ concentration ([Ca2+]cyto) in vascular smooth muscle. Release from the SR is controlled by two intracellular receptor/channel complexes, the ryanodine receptor (RyR) and the inositol 1,4,5-trisphosphate receptor (IP3R). These receptors may be regulated by the accessory FK506-binding protein (FKBP) either directly, by binding to the channel, or indirectly via FKBP modulation of two targets, the phosphatase, calcineurin or the kinase, mammalian target of rapamycin (mTOR). Experimental approach: Single portal vein myocytes were voltage-clamped in whole cell configuration and [Ca2+]cyto measured using fluo-3. IP3Rs were activated by photolysis of caged IP3 and RyRs activated by hydrostatic application of caffeine. Key results: FK506 which displaces FKBP from each receptor (to inhibit calcineurin) increased the [Ca2+]cyto rise evoked by activation of either RyR or IP3R. Rapamycin which displaces FKBP (to inhibit mTOR) also increased the amplitude of the caffeine-evoked, but reduced the IP3-evoked [Ca2+]cyto rise. None of the phosphatase inhibitors, cypermethrin, okadaic acid or calcineurin inhibitory peptide, altered either caffeine- or IP3-evoked [Ca2+]cyto release; calcineurin did not contribute to FK506-mediated potentiation of RyR- or IP3R-mediated Ca2+ release. The mTOR inhibitor LY294002, like rapamycin, decreased IP3-evoked Ca2+ release. Conclusions and implications: Ca2+ release in portal vein myocytes, via RyR, was modulated directly by FKBP binding to the channel; neither calcineurin nor mTOR contributed to this regulation. However, IP3R-mediated Ca2+ release, while also modulated directly by FKBP may be additionally regulated by mTOR. Rapamycin inhibition of IP3-mediated Ca2+ release may be explained by mTOR inhibition.
LanguageEnglish
Pages1112-1120
Number of pages9
JournalBritish Journal of Pharmacology
Volume158
Issue number4
DOIs
Publication statusPublished - Oct 2009

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Tacrolimus Binding Proteins
Sarcoplasmic Reticulum
Tacrolimus
Sirolimus
Vascular Smooth Muscle
Ryanodine Receptor Calcium Release Channel
Calcineurin
Caffeine
Portal Vein
Muscle Cells
Okadaic Acid
2-(4-morpholinyl)-8-phenyl-4H-1-benzopyran-4-one
Photolysis
Inositol
Phosphoric Monoester Hydrolases
Protein Binding
Phosphotransferases

Keywords

  • FK506
  • rapamycin
  • FK506-binding proteins
  • ryanodine receptor
  • inositol 1
  • 4
  • 5-trisphosphate receptor
  • mTOR
  • calcineurin
  • vascular smooth muscle
  • calcium

Cite this

@article{549a6e4b6db446db8ed5c7970525476b,
title = "Regulation by FK506 and rapamycin of Ca2+ release from the sarcoplasmic reticulum in vascular smooth muscle: the role of FK506 binding proteins and mTOR",
abstract = "Background and purpose: The sarcoplasmic reticulum (SR), regulates the cytoplasmic Ca2+ concentration ([Ca2+]cyto) in vascular smooth muscle. Release from the SR is controlled by two intracellular receptor/channel complexes, the ryanodine receptor (RyR) and the inositol 1,4,5-trisphosphate receptor (IP3R). These receptors may be regulated by the accessory FK506-binding protein (FKBP) either directly, by binding to the channel, or indirectly via FKBP modulation of two targets, the phosphatase, calcineurin or the kinase, mammalian target of rapamycin (mTOR). Experimental approach: Single portal vein myocytes were voltage-clamped in whole cell configuration and [Ca2+]cyto measured using fluo-3. IP3Rs were activated by photolysis of caged IP3 and RyRs activated by hydrostatic application of caffeine. Key results: FK506 which displaces FKBP from each receptor (to inhibit calcineurin) increased the [Ca2+]cyto rise evoked by activation of either RyR or IP3R. Rapamycin which displaces FKBP (to inhibit mTOR) also increased the amplitude of the caffeine-evoked, but reduced the IP3-evoked [Ca2+]cyto rise. None of the phosphatase inhibitors, cypermethrin, okadaic acid or calcineurin inhibitory peptide, altered either caffeine- or IP3-evoked [Ca2+]cyto release; calcineurin did not contribute to FK506-mediated potentiation of RyR- or IP3R-mediated Ca2+ release. The mTOR inhibitor LY294002, like rapamycin, decreased IP3-evoked Ca2+ release. Conclusions and implications: Ca2+ release in portal vein myocytes, via RyR, was modulated directly by FKBP binding to the channel; neither calcineurin nor mTOR contributed to this regulation. However, IP3R-mediated Ca2+ release, while also modulated directly by FKBP may be additionally regulated by mTOR. Rapamycin inhibition of IP3-mediated Ca2+ release may be explained by mTOR inhibition.",
keywords = "FK506, rapamycin, FK506-binding proteins, ryanodine receptor, inositol 1, 4, 5-trisphosphate receptor, mTOR, calcineurin, vascular smooth muscle, calcium",
author = "D. MacMillan and J.G. McCarron",
year = "2009",
month = "10",
doi = "10.1111/j.1476-5381.2009.00369.x",
language = "English",
volume = "158",
pages = "1112--1120",
journal = "British Journal of Pharmacology",
issn = "0007-1188",
number = "4",

}

TY - JOUR

T1 - Regulation by FK506 and rapamycin of Ca2+ release from the sarcoplasmic reticulum in vascular smooth muscle

T2 - British Journal of Pharmacology

AU - MacMillan, D.

AU - McCarron, J.G.

PY - 2009/10

Y1 - 2009/10

N2 - Background and purpose: The sarcoplasmic reticulum (SR), regulates the cytoplasmic Ca2+ concentration ([Ca2+]cyto) in vascular smooth muscle. Release from the SR is controlled by two intracellular receptor/channel complexes, the ryanodine receptor (RyR) and the inositol 1,4,5-trisphosphate receptor (IP3R). These receptors may be regulated by the accessory FK506-binding protein (FKBP) either directly, by binding to the channel, or indirectly via FKBP modulation of two targets, the phosphatase, calcineurin or the kinase, mammalian target of rapamycin (mTOR). Experimental approach: Single portal vein myocytes were voltage-clamped in whole cell configuration and [Ca2+]cyto measured using fluo-3. IP3Rs were activated by photolysis of caged IP3 and RyRs activated by hydrostatic application of caffeine. Key results: FK506 which displaces FKBP from each receptor (to inhibit calcineurin) increased the [Ca2+]cyto rise evoked by activation of either RyR or IP3R. Rapamycin which displaces FKBP (to inhibit mTOR) also increased the amplitude of the caffeine-evoked, but reduced the IP3-evoked [Ca2+]cyto rise. None of the phosphatase inhibitors, cypermethrin, okadaic acid or calcineurin inhibitory peptide, altered either caffeine- or IP3-evoked [Ca2+]cyto release; calcineurin did not contribute to FK506-mediated potentiation of RyR- or IP3R-mediated Ca2+ release. The mTOR inhibitor LY294002, like rapamycin, decreased IP3-evoked Ca2+ release. Conclusions and implications: Ca2+ release in portal vein myocytes, via RyR, was modulated directly by FKBP binding to the channel; neither calcineurin nor mTOR contributed to this regulation. However, IP3R-mediated Ca2+ release, while also modulated directly by FKBP may be additionally regulated by mTOR. Rapamycin inhibition of IP3-mediated Ca2+ release may be explained by mTOR inhibition.

AB - Background and purpose: The sarcoplasmic reticulum (SR), regulates the cytoplasmic Ca2+ concentration ([Ca2+]cyto) in vascular smooth muscle. Release from the SR is controlled by two intracellular receptor/channel complexes, the ryanodine receptor (RyR) and the inositol 1,4,5-trisphosphate receptor (IP3R). These receptors may be regulated by the accessory FK506-binding protein (FKBP) either directly, by binding to the channel, or indirectly via FKBP modulation of two targets, the phosphatase, calcineurin or the kinase, mammalian target of rapamycin (mTOR). Experimental approach: Single portal vein myocytes were voltage-clamped in whole cell configuration and [Ca2+]cyto measured using fluo-3. IP3Rs were activated by photolysis of caged IP3 and RyRs activated by hydrostatic application of caffeine. Key results: FK506 which displaces FKBP from each receptor (to inhibit calcineurin) increased the [Ca2+]cyto rise evoked by activation of either RyR or IP3R. Rapamycin which displaces FKBP (to inhibit mTOR) also increased the amplitude of the caffeine-evoked, but reduced the IP3-evoked [Ca2+]cyto rise. None of the phosphatase inhibitors, cypermethrin, okadaic acid or calcineurin inhibitory peptide, altered either caffeine- or IP3-evoked [Ca2+]cyto release; calcineurin did not contribute to FK506-mediated potentiation of RyR- or IP3R-mediated Ca2+ release. The mTOR inhibitor LY294002, like rapamycin, decreased IP3-evoked Ca2+ release. Conclusions and implications: Ca2+ release in portal vein myocytes, via RyR, was modulated directly by FKBP binding to the channel; neither calcineurin nor mTOR contributed to this regulation. However, IP3R-mediated Ca2+ release, while also modulated directly by FKBP may be additionally regulated by mTOR. Rapamycin inhibition of IP3-mediated Ca2+ release may be explained by mTOR inhibition.

KW - FK506

KW - rapamycin

KW - FK506-binding proteins

KW - ryanodine receptor

KW - inositol 1

KW - 4

KW - 5-trisphosphate receptor

KW - mTOR

KW - calcineurin

KW - vascular smooth muscle

KW - calcium

U2 - 10.1111/j.1476-5381.2009.00369.x

DO - 10.1111/j.1476-5381.2009.00369.x

M3 - Article

VL - 158

SP - 1112

EP - 1120

JO - British Journal of Pharmacology

JF - British Journal of Pharmacology

SN - 0007-1188

IS - 4

ER -