Over‐expression of FK506‐binding protein FKBP12.6 alters excitation–contraction coupling in adult rabbit cardiomyocytes

Loughrey, Christopher M.; Seidler, Tim; Miller, S.; Prestle, J.; MacEachern, K.E.; Reynolds, Deborah F.; Hasenfuß, Gerd; Smith, Godfrey L.

doi:10.1113/jphysiol.2003.057166

Cited by 52 publications

(54 citation statements)

References 35 publications

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“…This means that only ,35% of available sites are occupied in mouse RyR2, ,45% in pig and rat RyR2, and virtually zero in rabbit. This finding might explain the beneficial effects on SR Ca 2+ handling upon FKBP12.6 overexpression in isolated cardiomyocytes (Gomez et al, 2004;Loughrey et al, 2004;Prestle et al, 2001) or in transgenic animals (Gellen et al, 2008;Huang et al, 2006;Seidler et al, 2011). If RyR2 channels were already saturated by FKBP12.6, then overexpression of this protein should be ineffective in improving SR Ca 2+ handling, as previously suggested (Gellen et al, 2008).…”

Section: Discussionmentioning

confidence: 71%

“…The finding that FKBP12.6 occupancy of RyR2 is low (or near absent in rabbit) suggests that this protein might not be vital for normal heart function. However, at full saturation FKBP12.6 has the potential to further stabilise RyR2 function and reduce diastolic SR Ca 2+ leak, as indicated by overexpression studies in isolated cardiomyocytes (Gomez et al, 2004;Loughrey et al, 2004;Prestle et al, 2001) and transgenic animals (Gellen et al, 2008;Huang et al, 2006;Seidler et al, 2011). Recent work has demonstrated that FKBP12.6 levels are increased in the late preconditioned myocardium and that this protects against myocardial stunning (Lucats et al, 2007).…”

Section: Implications For Ryr2 Pathophysiologymentioning

confidence: 99%

“…FKBP12.6 overexpression in transgenic mice results in reduced Ca 2+ spark frequency, enhanced contractility and cardiac output (Gellen et al, 2008;Huang et al, 2006). Adenovirus-mediated FKBP12.6 overexpression in isolated cardiomyocytes results in increased electrically evoked Ca 2+ transients and SR Ca 2+ content, but decreased Ca 2+ spark frequency, amplitude and duration (Gomez et al, 2004;Loughrey et al, 2004;Prestle et al, 2001). Although the increased Ca 2+ transients upon FKBP12.6 overexpression seem to contradict the results for FK506 and rapamycin treatment (where increased Ca 2+ transients also observed), the former were due to an increased SR Ca 2+ content, most probably resulting from suppression of the spontaneous RyR2 activity.…”

Section: Introductionmentioning

confidence: 99%

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Disparate Ryanodine Receptor Association with the FK506-binding Proteins in Mammalian Heart

Zissimopoulos¹,

Seifan²,

Maxwell³

et al. 2012

Journal of Cell Science

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SummaryThe FK506-binding proteins (FKBP12 and FKBP12.6; also known as FKBP1A and FKBP1B, respectively) are accessory subunits of the ryanodine receptor (RyR) Ca 2+ release channel. Aberrant RyR2-FKBP12.6 interactions have been proposed to be the underlying cause of channel dysfunction in acquired and inherited cardiac disease. However, the stoichiometry of the RyR2 association with FKBP12 or FKBP12.6 in mammalian heart is currently unknown. Here, we describe detailed quantitative analysis of cardiac stoichiometry between RyR2 and FKBP12 or FKBP12.6 using immunoblotting and [3 H]ryanodine-binding assays, revealing striking disparities between four mammalian species. In mouse and pig heart, RyR2 is found complexed with both FKBP12 and FKBP12.6, although the former is the most abundant isoform. In rat heart, RyR2 is predominantly associated with FKBP12.6, whereas in rabbit it is associated with FKBP12 only. Co-immunoprecipitation experiments demonstrate RyR2-specific interaction with both FKBP isoforms in native cardiac tissue. Assuming four FKBP-binding sites per RyR2 tetramer, only a small proportion of available sites are occupied by endogenous FKBP12.6. FKBP interactions with RyR2 are very strong and resistant to drug (FK506, rapamycin and cyclic ADPribose) and redox (H 2 O 2 and diamide) treatment. By contrast, the RyR1-FKBP12 association in skeletal muscle is readily disrupted under oxidative conditions. This is the first study to directly assess association of endogenous FKBP12 and FKBP12.6 with RyR2 in native cardiac tissue. Our results challenge the widespread perception that RyR2 associates exclusively with FKBP12.6 to near saturation, with important implications for the role of the FK506-binding proteins in RyR2 pathophysiology and cardiac disease.

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Section: Discussionmentioning

confidence: 71%

Section: Implications For Ryr2 Pathophysiologymentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Disparate Ryanodine Receptor Association with the FK506-binding Proteins in Mammalian Heart

Zissimopoulos¹,

Seifan²,

Maxwell³

et al. 2012

Journal of Cell Science

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“…Overexpression of FKBP12.0 (809) had opposing effects on Ca 2ϩ spark amplitude, duration, and frequency relative to acutely transduced FKBP12.6 myocytes (513,710). Additionally, FKBP12.0 reduced the sensitivity of the cardiac RyR to the CICR mechanism causing a decrease in EC coupling gain (809), a result not seen in FKBP12.6 transduced rabbit myocytes (513,710 (414,792) and acute genetic manipulation studies (571,877), but the focus here will be placed primarily on results obtained from acute gene transfer. Acute two-to fourfold overexpression of CSQ in adult rat and rabbit cardiac myocytes directly increased SR Ca 2ϩ content as assessed by rapid caffeine application (571,877).…”

Section: Fkbp126/calstabin2mentioning

confidence: 99%

Designing Heart Performance by Gene Transfer

Davis¹,

Westfall²,

Townsend³

et al. 2008

Physiological Reviews

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The birth of molecular cardiology can be traced to the development and implementation of high-fidelity genetic approaches for manipulating the heart. Recombinant viral vector-based technology offers a highly effective approach to genetically engineer cardiac muscle in vitro and in vivo. This review highlights discoveries made in cardiac muscle physiology through the use of targeted viral-mediated genetic modification. Here the history of cardiac gene transfer technology and the strengths and limitations of viral and nonviral vectors for gene delivery are reviewed. A comprehensive account is given of the application of gene transfer technology for studying key cardiac muscle targets including Ca2+handling, the sarcomere, the cytoskeleton, and signaling molecules and their posttranslational modifications. The primary objective of this review is to provide a thorough analysis of gene transfer studies for understanding cardiac physiology in health and disease. By comparing results obtained from gene transfer with those obtained from transgenesis and biophysical and biochemical methodologies, this review provides a global view of cardiac structure-function with an eye towards future areas of research. The data presented here serve as a basis for discovery of new therapeutic targets for remediation of acquired and inherited cardiac diseases.

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“…At present, three approaches have been used to probe the in situ regulatory role of FKBP12.6: 1) the use of pharmacological agents to disrupt the FKBP12.6-RyR2 interaction (8,12), 2) transgenic animal models that lack FKBP12.6 (38,45), and 3) short-term overexpression of FKBP12.6 in cultured adult heart cells (12,13,22,29). However, important limitations are associated with each approach.…”

mentioning

confidence: 99%

Reconstitution of local Ca²⁺ signaling between cardiac L-type Ca²⁺ channels and ryanodine receptors: insights into regulation by FKBP12.6

Chen¹,

Dirksen²

2005

American Journal of Physiology-Cell Physiology

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Ca+-induced Ca2+ release (CICR) in the heart involves local Ca2+ signaling between sarcolemmal L-type Ca2+ channels (dihydropyridine receptors, DHPRs) and type 2 ryanodine receptors (RyR2s) in the sarcoplasmic reticulum (SR). We reconstituted cardiac-like CICR by expressing a cardiac dihydropyridine-insensitive (T1066Y/Q1070M) α1-subunit (α1CYM) and RyR2 in myotubes derived from RyR1-knockout (dyspedic) mice. Myotubes expressing α1CYM and RyR2 were vesiculated and exhibited spontaneous Ca2+ oscillations that resulted in chaotic and uncontrolled contractions. Coexpression of FKBP12.6 (but not FKBP12.0) with α1CYM and RyR2 eliminated vesiculations and reduced the percentage of myotubes exhibiting uncontrolled global Ca2+ oscillations (63% and 13% of cells exhibited oscillations in the absence and presence of FKBP12.6, respectively). α1CYM/RyR2/FKBP12.6-expressing myotubes exhibited robust and rapid electrically evoked Ca2+ transients that required extracellular Ca2+. Depolarization-induced Ca2+ release in α1CYM/RyR2/FKBP12.6-expressing myotubes exhibited a bell-shaped voltage dependence that was fourfold larger than that of myotubes expressing α1CYM alone (maximal fluorescence change was 2.10 ± 0.39 and 0.54 ± 0.07, respectively), despite similar Ca2+ current densities. In addition, the gain of CICR in α1CYM/RyR2/FKBP12.6-expressing myotubes exhibited a nonlinear voltage dependence, being considerably larger at threshold potentials. We used this molecular model of local α1C-RyR2 signaling to assess the ability of FKBP12.6 to inhibit spontaneous Ca2+ release via a phosphomimetic mutation in RyR2 (S2808D). Electrically evoked Ca2+ release and the incidence of spontaneous Ca2+ oscillations did not differ in wild-type RyR2- and S2808D-expressing myotubes over a wide range of FKBP12.6 expression. Thus a negative charge at S2808 does not alter in situ regulation of RyR2 by FKBP12.6.

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Over‐expression of FK506‐binding protein FKBP12.6 alters excitation–contraction coupling in adult rabbit cardiomyocytes

Cited by 52 publications

References 35 publications

Disparate Ryanodine Receptor Association with the FK506-binding Proteins in Mammalian Heart

Disparate Ryanodine Receptor Association with the FK506-binding Proteins in Mammalian Heart

Designing Heart Performance by Gene Transfer

Reconstitution of local Ca²⁺ signaling between cardiac L-type Ca²⁺ channels and ryanodine receptors: insights into regulation by FKBP12.6

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Over‐expression of FK506‐binding protein FKBP12.6 alters excitation–contraction coupling in adult rabbit cardiomyocytes

Cited by 52 publications

References 35 publications

Disparate Ryanodine Receptor Association with the FK506-binding Proteins in Mammalian Heart

Disparate Ryanodine Receptor Association with the FK506-binding Proteins in Mammalian Heart

Designing Heart Performance by Gene Transfer

Reconstitution of local Ca2+ signaling between cardiac L-type Ca2+ channels and ryanodine receptors: insights into regulation by FKBP12.6

Contact Info

Product

Resources

About

Reconstitution of local Ca²⁺ signaling between cardiac L-type Ca²⁺ channels and ryanodine receptors: insights into regulation by FKBP12.6