FKBP12.6 overexpression decreases Ca2+ spark amplitude but enhances [Ca2+]i transient in rat cardiac myocytes

Gómez, Ana M.; Schuster, Iris; Fauconnier, Jérémy; Prestle, J.; Hasenfuß, Gerd; Richard, Sylvain

doi:10.1152/ajpheart.00409.2004

Cited by 55 publications

(54 citation statements)

References 35 publications

(66 reference statements)

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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: 65%

“…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: 65%

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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“…It is a 12.6-kDa protein that is thought to bind to each subunit of the channel in a 1:1 ratio on the cytosolic side of RyR (478,951). FKBP12.6 is considered a RyR channel stabilizer in the closed state during diastole, and it appears to faciltitate the functional coupling of RyR channels (534,981 (280,710). Unique to the rat myocyte was the finding that FKBP12.6 overexpression hastened Ca 2ϩ transient decay (280,710).…”

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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“…In a previous study, modulators of RyR1 open and closed states had no effect on the quantity of FKBP12 bound to RyR1 in GST-FKBP12 pulldown assays (Bultynck et al, 2001), thus our observations reflect the discriminatory power of the SPR technique. The impact of complete loss of FKBP12/12.6 from RyR1/RyR2 are changes in the stability of the open/closed state of RyR in bilayers (Ahern et al, 1997;Brillantes et al, 1994;Chen et al, 1994;Ma et al, 1995) and altered EC coupling and Ca 2+ sparks in skeletal (Avila et al, 2003) and cardiac (Gomez et al, 2004;Prestle et al, 2001;Xiao et al, 1997) myocytes. Our data suggests that, because FKBP12 dissociates slowly and retains a comparatively high affinity for the open channel, loss of FKBP12 from RyR may not be a part of the normal EC coupling cycle.…”

Section: Discussionmentioning

confidence: 99%

Ryanodine receptor binding to FKBP12 is modulated by channel activation state

Jones

Reynolds

Lai

et al. 2005

Journal of Cell Science

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Ryanodine receptor (RyR) Ca2+ release channels undergo a conformational change between the open and closed states. Its protein modulator, FK506 binding protein 12 (FKBP12), stabilises the channel gating between the four subunits that surround a central Ca2+-conducting pore. To understand the interdependence of RyR and FKBP12 binding, physiological and pharmacological agents were used to modulate the RyR open/closed state. ELISA sandwich binding assays showed that FKBP12 binding was dependent on the free Ca2+ and was lower at 1-10 μM free Ca2+ compared with 1 mM EGTA and 1 mM Ca2+, and this effect was enhanced by the inclusion of 1 mM ATP. Ruthenium red increased the binding of FKBP12. [3H]Ryanodine binding confirmed that 1 mM EGTA, 1 mM Ca2+ and 1 μM ruthenium red closed the channel, whereas 1 μM free Ca2+, 1 μM free Ca2+ + 1 mM ATP, or 10 mM caffeine opened it. These binding conditions were used in surface plasmon resonance studies to measure equilibrium binding kinetics. The affinity constant KA was significantly greater for the closed than the open channel, a change mediated by a decreased dissociation rate constant, kd. The results show that surface plasmon resonance is a powerful technique that can measure differences in RyR1 equilibrium binding kinetics with FKBP12.

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FKBP12.6 overexpression decreases Ca²⁺ spark amplitude but enhances [Ca²⁺]_i transient in rat cardiac myocytes

Abstract: Gómez, Ana M., Iris Schuster, Jérémy Fauconnier, Jü rgen Prestle, Gerd Hasenfuss, and Sylvain Richard. FKBP12.6 overexpression decreases Ca 2ϩ spark amplitude but enhances [Ca 2ϩ ]i transient in rat cardiac myocytes.

Cited by 55 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

Ryanodine receptor binding to FKBP12 is modulated by channel activation state

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