FK506-binding protein (FKBP12) regulates ryanodine receptor-evoked Ca2+ release in colonic but not aortic smooth muscle

D. MacMillan, S. Currie, J.G. McCarron

Research output: Contribution to journalArticle

11 Citations (Scopus)

Abstract

In smooth muscle, the ryanodine receptor (RyR) mediates Ca2+ release from the sarcoplasmic reticulum (SR) Ca2+ store. Release may be regulated by the RyR accessory FK506-binding protein (FKBP12) either directly, as a result of FKBP12 binding to RyR, or indirectly via modulation of the activity of the phosphatase calcineurin or kinase mTOR. Here we report that RyR-mediated Ca2+ release is modulated by FKBP12 in colonic but not aortic myocytes. Neither calcineurin nor mTOR are required for FKBP12 modulation of Ca2+ release in colonic myocytes to occur. In colonic myocytes, co-immunoprecipitation techniques established that FKBP12 and calcineurin each associated with the RyR2 receptor isoform (the main isoform in this tissue). Single colonic myocytes were voltage clamped in the whole cell configuration and cytoplasmic Ca2+ concentration ([Ca2+]c) increases evoked by the RyR activator caffeine. Under these conditions FK506, which displaces FKBP12 (to inhibit calcineurin) and rapamycin, which displaces FKBP12 (to inhibit mTOR), each increased the [Ca2+]c rise evoked by caffeine. Notwithstanding, neither mTOR nor calcineurin are required to potentiate caffeine-evoked Ca2+ increases evoked by each drug. Thus, the mTOR and phosphatidylinositol 3-kinase inhibitor, LY294002, which directly inhibits mTOR without removing FKBP12 from RyR, did not alter caffeine-evoked [Ca2+]c transients. Nor did inhibition of calcineurin by cypermethrin, okadaic acid or calcineurin inhibitory peptide block the FK506-induced increase in RyR-mediated Ca2+ release. In aorta, although RyR3 (the main isoform), FKBP12 and calcineurin were each present, RyR-mediated Ca2+ release was unaffected by either FK506, rapamycin or the calcineurin inhibitors cypermethrin and okadaic acid in single voltage clamped aortic myocytes. Presumably failure of FKBP12 to associate with RyR3 resulted in the immunosuppressant drugs (FK506 and rapamycin) being unable to alter the activity of RyR. The effects of these drugs are therefore, apparently dependent on an association of FKBP12 with RyR. Together, removal of FKBP12 from RyR augmented Ca2+ release via the channel in colonic myocytes. Neither calcineurin nor mTOR are required for the FK506- or rapamycin-induced potentiation of RyR Ca2+ release to occur. The results indicate that FKBP12 directly inhibits RyR channel activity in colonic myocytes but not in aorta.
LanguageEnglish
Pages539-549
Number of pages10
JournalCell Calcium
Volume43
Issue number6
DOIs
Publication statusPublished - 2008

Fingerprint

Tacrolimus Binding Protein 1A
Tacrolimus Binding Proteins
Ryanodine Receptor Calcium Release Channel
Smooth Muscle
Calcineurin
Muscle Cells
Tacrolimus
Sirolimus
Caffeine
Okadaic Acid
Protein Isoforms
Aorta
Phosphatidylinositol 3-Kinase
Pharmaceutical Preparations

Keywords

  • FK506-binding proteins
  • ryanodine receptor
  • calcineurin
  • smooth muscle
  • biomedical sciences

Cite this

@article{a9ff72a68b53439d80a96c9dc4a48c0c,
title = "FK506-binding protein (FKBP12) regulates ryanodine receptor-evoked Ca2+ release in colonic but not aortic smooth muscle",
abstract = "In smooth muscle, the ryanodine receptor (RyR) mediates Ca2+ release from the sarcoplasmic reticulum (SR) Ca2+ store. Release may be regulated by the RyR accessory FK506-binding protein (FKBP12) either directly, as a result of FKBP12 binding to RyR, or indirectly via modulation of the activity of the phosphatase calcineurin or kinase mTOR. Here we report that RyR-mediated Ca2+ release is modulated by FKBP12 in colonic but not aortic myocytes. Neither calcineurin nor mTOR are required for FKBP12 modulation of Ca2+ release in colonic myocytes to occur. In colonic myocytes, co-immunoprecipitation techniques established that FKBP12 and calcineurin each associated with the RyR2 receptor isoform (the main isoform in this tissue). Single colonic myocytes were voltage clamped in the whole cell configuration and cytoplasmic Ca2+ concentration ([Ca2+]c) increases evoked by the RyR activator caffeine. Under these conditions FK506, which displaces FKBP12 (to inhibit calcineurin) and rapamycin, which displaces FKBP12 (to inhibit mTOR), each increased the [Ca2+]c rise evoked by caffeine. Notwithstanding, neither mTOR nor calcineurin are required to potentiate caffeine-evoked Ca2+ increases evoked by each drug. Thus, the mTOR and phosphatidylinositol 3-kinase inhibitor, LY294002, which directly inhibits mTOR without removing FKBP12 from RyR, did not alter caffeine-evoked [Ca2+]c transients. Nor did inhibition of calcineurin by cypermethrin, okadaic acid or calcineurin inhibitory peptide block the FK506-induced increase in RyR-mediated Ca2+ release. In aorta, although RyR3 (the main isoform), FKBP12 and calcineurin were each present, RyR-mediated Ca2+ release was unaffected by either FK506, rapamycin or the calcineurin inhibitors cypermethrin and okadaic acid in single voltage clamped aortic myocytes. Presumably failure of FKBP12 to associate with RyR3 resulted in the immunosuppressant drugs (FK506 and rapamycin) being unable to alter the activity of RyR. The effects of these drugs are therefore, apparently dependent on an association of FKBP12 with RyR. Together, removal of FKBP12 from RyR augmented Ca2+ release via the channel in colonic myocytes. Neither calcineurin nor mTOR are required for the FK506- or rapamycin-induced potentiation of RyR Ca2+ release to occur. The results indicate that FKBP12 directly inhibits RyR channel activity in colonic myocytes but not in aorta.",
keywords = "FK506-binding proteins, ryanodine receptor, calcineurin, smooth muscle, biomedical sciences",
author = "D. MacMillan and S. Currie and J.G. McCarron",
year = "2008",
doi = "10.1016/j.ceca.2007.09.002",
language = "English",
volume = "43",
pages = "539--549",
journal = "Cell Calcium",
issn = "0143-4160",
number = "6",

}

FK506-binding protein (FKBP12) regulates ryanodine receptor-evoked Ca2+ release in colonic but not aortic smooth muscle. / MacMillan, D.; Currie, S.; McCarron, J.G.

In: Cell Calcium, Vol. 43, No. 6, 2008, p. 539-549.

Research output: Contribution to journalArticle

TY - JOUR

T1 - FK506-binding protein (FKBP12) regulates ryanodine receptor-evoked Ca2+ release in colonic but not aortic smooth muscle

AU - MacMillan, D.

AU - Currie, S.

AU - McCarron, J.G.

PY - 2008

Y1 - 2008

N2 - In smooth muscle, the ryanodine receptor (RyR) mediates Ca2+ release from the sarcoplasmic reticulum (SR) Ca2+ store. Release may be regulated by the RyR accessory FK506-binding protein (FKBP12) either directly, as a result of FKBP12 binding to RyR, or indirectly via modulation of the activity of the phosphatase calcineurin or kinase mTOR. Here we report that RyR-mediated Ca2+ release is modulated by FKBP12 in colonic but not aortic myocytes. Neither calcineurin nor mTOR are required for FKBP12 modulation of Ca2+ release in colonic myocytes to occur. In colonic myocytes, co-immunoprecipitation techniques established that FKBP12 and calcineurin each associated with the RyR2 receptor isoform (the main isoform in this tissue). Single colonic myocytes were voltage clamped in the whole cell configuration and cytoplasmic Ca2+ concentration ([Ca2+]c) increases evoked by the RyR activator caffeine. Under these conditions FK506, which displaces FKBP12 (to inhibit calcineurin) and rapamycin, which displaces FKBP12 (to inhibit mTOR), each increased the [Ca2+]c rise evoked by caffeine. Notwithstanding, neither mTOR nor calcineurin are required to potentiate caffeine-evoked Ca2+ increases evoked by each drug. Thus, the mTOR and phosphatidylinositol 3-kinase inhibitor, LY294002, which directly inhibits mTOR without removing FKBP12 from RyR, did not alter caffeine-evoked [Ca2+]c transients. Nor did inhibition of calcineurin by cypermethrin, okadaic acid or calcineurin inhibitory peptide block the FK506-induced increase in RyR-mediated Ca2+ release. In aorta, although RyR3 (the main isoform), FKBP12 and calcineurin were each present, RyR-mediated Ca2+ release was unaffected by either FK506, rapamycin or the calcineurin inhibitors cypermethrin and okadaic acid in single voltage clamped aortic myocytes. Presumably failure of FKBP12 to associate with RyR3 resulted in the immunosuppressant drugs (FK506 and rapamycin) being unable to alter the activity of RyR. The effects of these drugs are therefore, apparently dependent on an association of FKBP12 with RyR. Together, removal of FKBP12 from RyR augmented Ca2+ release via the channel in colonic myocytes. Neither calcineurin nor mTOR are required for the FK506- or rapamycin-induced potentiation of RyR Ca2+ release to occur. The results indicate that FKBP12 directly inhibits RyR channel activity in colonic myocytes but not in aorta.

AB - In smooth muscle, the ryanodine receptor (RyR) mediates Ca2+ release from the sarcoplasmic reticulum (SR) Ca2+ store. Release may be regulated by the RyR accessory FK506-binding protein (FKBP12) either directly, as a result of FKBP12 binding to RyR, or indirectly via modulation of the activity of the phosphatase calcineurin or kinase mTOR. Here we report that RyR-mediated Ca2+ release is modulated by FKBP12 in colonic but not aortic myocytes. Neither calcineurin nor mTOR are required for FKBP12 modulation of Ca2+ release in colonic myocytes to occur. In colonic myocytes, co-immunoprecipitation techniques established that FKBP12 and calcineurin each associated with the RyR2 receptor isoform (the main isoform in this tissue). Single colonic myocytes were voltage clamped in the whole cell configuration and cytoplasmic Ca2+ concentration ([Ca2+]c) increases evoked by the RyR activator caffeine. Under these conditions FK506, which displaces FKBP12 (to inhibit calcineurin) and rapamycin, which displaces FKBP12 (to inhibit mTOR), each increased the [Ca2+]c rise evoked by caffeine. Notwithstanding, neither mTOR nor calcineurin are required to potentiate caffeine-evoked Ca2+ increases evoked by each drug. Thus, the mTOR and phosphatidylinositol 3-kinase inhibitor, LY294002, which directly inhibits mTOR without removing FKBP12 from RyR, did not alter caffeine-evoked [Ca2+]c transients. Nor did inhibition of calcineurin by cypermethrin, okadaic acid or calcineurin inhibitory peptide block the FK506-induced increase in RyR-mediated Ca2+ release. In aorta, although RyR3 (the main isoform), FKBP12 and calcineurin were each present, RyR-mediated Ca2+ release was unaffected by either FK506, rapamycin or the calcineurin inhibitors cypermethrin and okadaic acid in single voltage clamped aortic myocytes. Presumably failure of FKBP12 to associate with RyR3 resulted in the immunosuppressant drugs (FK506 and rapamycin) being unable to alter the activity of RyR. The effects of these drugs are therefore, apparently dependent on an association of FKBP12 with RyR. Together, removal of FKBP12 from RyR augmented Ca2+ release via the channel in colonic myocytes. Neither calcineurin nor mTOR are required for the FK506- or rapamycin-induced potentiation of RyR Ca2+ release to occur. The results indicate that FKBP12 directly inhibits RyR channel activity in colonic myocytes but not in aorta.

KW - FK506-binding proteins

KW - ryanodine receptor

KW - calcineurin

KW - smooth muscle

KW - biomedical sciences

UR - http://dx.doi.org/10.1016/j.ceca.2007.09.002

U2 - 10.1016/j.ceca.2007.09.002

DO - 10.1016/j.ceca.2007.09.002

M3 - Article

VL - 43

SP - 539

EP - 549

JO - Cell Calcium

T2 - Cell Calcium

JF - Cell Calcium

SN - 0143-4160

IS - 6

ER -