- Title
- Ryanodine receptor modification and regulation by intracellular Ca²⁺ and Mg²⁺ in healthy and failing human hearts
- Creator
- Walweel, K.; Molenaar, P.; Imtiaz, M. S.; Denniss, A.; dos Remedios, C.; van Helden, D. F.; Dulhunty, A. F.; Laver, D. R.; Beard, N. A.
- Relation
- Funding BodyNHMRCGrant Number631052 http://purl.org/au-research/grants/nhmrc/631052
- Relation
- Journal of Molecular and Cellular Cardiology Vol. 104, Issue March, p. 53-62
- Publisher Link
- http://dx.doi.org/10.1016/j.yjmcc.2017.01.016
- Publisher
- Academic Press
- Resource Type
- journal article
- Date
- 2017
- Description
- Rationale: Heart failure is a multimodal disorder, of which disrupted Ca²⁺ homeostasis is a hallmark. Central to Ca²⁺ homeostasis is the major cardiac Ca²⁺ release channel - the ryanodine receptor (RyR2) - whose activity is influenced by associated proteins, covalent modification and by Ca²⁺ and Mg²⁺. That RyR2 is remodelled and its function disturbed in heart failure is well recognized, but poorly understood. Objective: To assess Ca²⁺ and Mg²⁺ regulation of RyR2 from left ventricles of healthy, cystic fibrosis and failing hearts, and to correlate these functional changes with RyR2 modifications and remodelling. Methods and results: The function of RyR2 from left ventricular samples was assessed using lipid bilayer single-channel measurements, whilst RyR2 modification and protein:protein interactions were determined using Western Blots and co-immunoprecipitation. In all failing hearts there was an increase in RyR2 activity at end-diastolic cytoplasmic Ca²⁺(100 nM), a decreased cytoplasmic [Ca²⁺] required for half maximal activation (Kₐ) and a decrease in inhibition by cytoplasmic Mg²⁺. This was accompanied by significant hyperphosphorylation of RyR2 S²⁸⁰⁸ and S²⁸¹⁴, reduced free thiol content and a reduced interaction with FKBP12.0 and FKBP12.6. Either dephosphorylation of RyR2 using PP1 or thiol reduction using DTT eliminated any significant difference in the activity of RyR2 from healthy and failing hearts. We also report a subgroup of RyR2 in failing hearts that were not responsive to regulation by intracellular Ca²⁺ or Mg²⁺. Conclusion: Despite different aetiologies, disrupted RyR2 Ca²⁺ sensitivity and biochemical modification of the channel are common constituents of failing heart RyR2 and may underlie the pathological disturbances in intracellular Ca²⁺ signalling.
- Subject
- ryanodine receptor; Mg²⁺ and Ca²⁺ signalling; heart failure; phosphorylation; lipid bilayer; regulatory proteins
- Identifier
- http://hdl.handle.net/1959.13/1391679
- Identifier
- uon:33274
- Identifier
- ISSN:0022-2828
- Language
- eng
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