scholarly journals The Pore Region of the Skeletal Muscle Ryanodine Receptor Is a Primary Locus for Excitation-Contraction Uncoupling in Central Core Disease

2003 ◽  
Vol 121 (4) ◽  
pp. 277-286 ◽  
Author(s):  
Guillermo Avila ◽  
Kristen M. S. O'Connell ◽  
Robert T. Dirksen
Keyword(s):  
Skeletal Muscle ◽  
Ryanodine Receptor ◽  
Central Core ◽  
Central Core Disease ◽  
Release Channel ◽  
Voltage Gated ◽  
Ryr1 Gene ◽  
Ec Coupling ◽  
Store Depletion ◽  
Sensor Activation

Human central core disease (CCD) is caused by mutations/deletions in the gene that encodes the skeletal muscle ryanodine receptor (RyR1). Previous studies have shown that CCD mutations in the NH2-terminal region of RyR1 lead to the formation of leaky SR Ca2+ release channels when expressed in myotubes derived from RyR1-knockout (dyspedic) mice, whereas a COOH-terminal mutant (I4897T) results in channels that are not leaky to Ca2+ but lack depolarization-induced Ca2+ release (termed excitation-contraction [EC] uncoupling). We show here that store depletion resulting from NH2-terminal (Y523S) and COOH-terminal (Y4795C) leaky CCD mutant release channels is eliminated after incorporation of the I4897T mutation into the channel (Y523S/I4897T and Y4795C/I4897T). In spite of normal SR Ca2+ content, myotubes expressing the double mutants lacked voltage-gated Ca2+ release and thus exhibited an EC uncoupling phenotype similar to that of I4897T-expressing myotubes. We also show that dyspedic myotubes expressing each of seven recently identified CCD mutations located in exon 102 of the RyR1 gene (G4890R, R4892W, I4897T, G4898E, G4898R, A4905V, R4913G) behave as EC-uncoupled release channels. Interestingly, voltage-gated Ca2+ release was nearly abolished (reduced ∼90%) while caffeine-induced Ca2+ release was only marginally reduced in R4892W-expressing myotubes, indicating that this mutation preferentially disrupts voltage-sensor activation of release. These data demonstrate that CCD mutations in exon 102 disrupt release channel permeation to Ca2+ during EC coupling and that this region represents a primary molecular locus for EC uncoupling in CCD.

scholarly journals Functional Effects of Central Core Disease Mutations in the Cytoplasmic Region of the Skeletal Muscle Ryanodine Receptor

2001 ◽  
Vol 118 (3) ◽  
pp. 277-290 ◽  
Author(s):  
Guillermo Avila ◽  
Robert T. Dirksen
Keyword(s):  
Skeletal Muscle ◽  
Ryanodine Receptor ◽  
Central Core ◽  
Central Core Disease ◽  
Calcium Release Channel ◽  
Release Channel ◽  
Voltage Gated ◽  
Channel Function ◽  
Store Depletion ◽  
The Impact

Central core disease (CCD) is a human myopathy that involves a dysregulation in muscle Ca2+ homeostasis caused by mutations in the gene encoding the skeletal muscle ryanodine receptor (RyR1), the protein that comprises the calcium release channel of the SR. Although genetic studies have clearly demonstrated linkage between mutations in RyR1 and CCD, the impact of these mutations on release channel function and excitation-contraction coupling in skeletal muscle is unknown. Toward this goal, we have engineered the different CCD mutations found in the NH2-terminal region of RyR1 into a rabbit RyR1 cDNA (R164C, I404M, Y523S, R2163H, and R2435H) and characterized the functional effects of these mutations after expression in myotubes derived from RyR1-knockout (dyspedic) mice. Resting Ca2+ levels were elevated in dyspedic myotubes expressing four of these mutants (Y523S > R2163H > R2435H R164C > I404M RyR1). A similar rank order was also found for the degree of SR Ca2+ depletion assessed using maximal concentrations of caffeine (10 mM) or cyclopiazonic acid (CPA, 30 μM). Although all of the CCD mutants fully restored L-current density, voltage-gated SR Ca2+ release was smaller and activated at more negative potentials for myotubes expressing the NH2-terminal CCD mutations. The shift in the voltage dependence of SR Ca2+ release correlated strongly with changes in resting Ca2+, SR Ca2+ store depletion, and peak voltage–gated release, indicating that increased release channel activity at negative membrane potentials promotes SR Ca2+ leak. Coexpression of wild-type and Y523S RyR1 proteins in dyspedic myotubes resulted in release channels that exhibited an intermediate degree of SR Ca2+ leak. These results demonstrate that the NH2-terminal CCD mutants enhance release channel sensitivity to activation by voltage in a manner that leads to increased SR Ca2+ leak, store depletion, and a reduction in voltage-gated Ca2+ release. Two fundamentally distinct cellular mechanisms (leaky channels and EC uncoupling) are proposed to explain how altered release channel function caused by different mutations in RyR1 could result in muscle weakness in CCD.

scholarly journals A central core disease mutation in the Ca2+-binding site of skeletal muscle ryanodine receptor impairs single-channel regulation

2019 ◽  
Vol 317 (2) ◽  
pp. C358-C365 ◽  
Author(s):  
Venkat R. Chirasani ◽  
Le Xu ◽  
Hannah G. Addis ◽  
Daniel A. Pasek ◽  
Nikolay V. Dokholyan ◽  
...  
Keyword(s):  
Skeletal Muscle ◽  
Amino Acid ◽  
Missense Mutation ◽  
Ryanodine Receptor ◽  
Single Channel ◽  
Central Core ◽  
Central Core Disease ◽  
Hek293 Cells ◽  
Amino Acid Residues ◽  
Single Channel Recordings

Cryoelectron microscopy and mutational analyses have shown that type 1 ryanodine receptor (RyR1) amino acid residues RyR1-E3893, -E3967, and -T5001 are critical for Ca2+-mediated activation of skeletal muscle Ca2+ release channel. De novo missense mutation RyR1-Q3970K in the secondary binding sphere of Ca2+ was reported in association with central core disease (CCD) in a 2-yr-old boy. Here, we characterized recombinant RyR1-Q3970K mutant by cellular Ca2+ release measurements, single-channel recordings, and computational methods. Caffeine-induced Ca2+ release studies indicated that RyR1-Q3970K formed caffeine-sensitive, Ca2+-conducting channel in HEK293 cells. However, in single-channel recordings, RyR1-Q3970K displayed low Ca2+-dependent channel activity and greatly reduced activation by caffeine or ATP. A RyR1-Q3970E mutant corresponds to missense mutation RyR2-Q3925E associated with arrhythmogenic syndrome in cardiac muscle. RyR1-Q3970E also formed caffeine-induced Ca2+ release in HEK293 cells and exhibited low activity in the presence of the activating ligand Ca2+ but, in contrast to RyR1-Q3970K, was activated by ATP and caffeine in single-channel recordings. Computational analyses suggested distinct structural rearrangements in the secondary binding sphere of Ca2+ of the two mutants, whereas the interaction of Ca2+ with directly interacting RyR1 amino acid residues Glu3893, Glu3967, and Thr5001 was only minimally affected. We conclude that RyR1-Q3970 has a critical role in Ca2+-dependent activation of RyR1 and that a missense RyR1-Q3970K mutant may give rise to myopathy in skeletal muscle.

scholarly journals PKA phosphorylation activates the calcium release channel (ryanodine receptor) in skeletal muscle

2003 ◽  
Vol 160 (6) ◽  
pp. 919-928 ◽  
Author(s):  
Steven Reiken ◽  
Alain Lacampagne ◽  
Hua Zhou ◽  
Aftab Kherani ◽  
Stephan E. Lehnart ◽  
...  
Keyword(s):  
Skeletal Muscle ◽  
Ryanodine Receptor ◽  
Calcium Release ◽  
Calcium Release Channel ◽  
Skeletal Muscle Function ◽  
Release Channel ◽  
Fk506 Binding Protein ◽  
Ec Coupling ◽  
Increased Activity

The type 1 ryanodine receptor (RyR1) on the sarcoplasmic reticulum (SR) is the major calcium (Ca2+) release channel required for skeletal muscle excitation–contraction (EC) coupling. RyR1 function is modulated by proteins that bind to its large cytoplasmic scaffold domain, including the FK506 binding protein (FKBP12) and PKA. PKA is activated during sympathetic nervous system (SNS) stimulation. We show that PKA phosphorylation of RyR1 at Ser2843 activates the channel by releasing FKBP12. When FKB12 is bound to RyR1, it inhibits the channel by stabilizing its closed state. RyR1 in skeletal muscle from animals with heart failure (HF), a chronic hyperadrenergic state, were PKA hyperphosphorylated, depleted of FKBP12, and exhibited increased activity, suggesting that the channels are “leaky.” RyR1 PKA hyperphosphorylation correlated with impaired SR Ca2+ release and early fatigue in HF skeletal muscle. These findings identify a novel mechanism that regulates RyR1 function via PKA phosphorylation in response to SNS stimulation. PKA hyperphosphorylation of RyR1 may contribute to impaired skeletal muscle function in HF, suggesting that a generalized EC coupling myopathy may play a role in HF.

scholarly journals Muscle weakness in Ryr1I4895T/WT knock-in mice as a result of reduced ryanodine receptor Ca2+ ion permeation and release from the sarcoplasmic reticulum

2010 ◽  
Vol 137 (1) ◽  
pp. 43-57 ◽  
Author(s):  
Ryan E. Loy ◽  
Murat Orynbayev ◽  
Le Xu ◽  
Zoita Andronache ◽  
Simona Apostol ◽  
...  
Keyword(s):  
Skeletal Muscle ◽  
Sarcoplasmic Reticulum ◽  
Ryanodine Receptor ◽  
Muscle Weakness ◽  
Dominant Negative ◽  
Release Mechanism ◽  
Ion Permeation ◽  
Release Channel ◽  
Ec Coupling

The type 1 isoform of the ryanodine receptor (RYR1) is the Ca2+ release channel of the sarcoplasmic reticulum (SR) that is activated during skeletal muscle excitation–contraction (EC) coupling. Mutations in the RYR1 gene cause several rare inherited skeletal muscle disorders, including malignant hyperthermia and central core disease (CCD). The human RYR1I4898T mutation is one of the most common CCD mutations. To elucidate the mechanism by which RYR1 function is altered by this mutation, we characterized in vivo muscle strength, EC coupling, SR Ca2+ content, and RYR1 Ca2+ release channel function using adult heterozygous Ryr1I4895T/+ knock-in mice (IT/+). Compared with age-matched wild-type (WT) mice, IT/+ mice exhibited significantly reduced upper body and grip strength. In spite of normal total SR Ca2+ content, both electrically evoked and 4-chloro-m-cresol–induced Ca2+ release were significantly reduced and slowed in single intact flexor digitorum brevis fibers isolated from 4–6-mo-old IT/+ mice. The sensitivity of the SR Ca2+ release mechanism to activation was not enhanced in fibers of IT/+ mice. Single-channel measurements of purified recombinant channels incorporated in planar lipid bilayers revealed that Ca2+ permeation was abolished for homotetrameric IT channels and significantly reduced for heterotetrameric WT:IT channels. Collectively, these findings indicate that in vivo muscle weakness observed in IT/+ knock-in mice arises from a reduction in the magnitude and rate of RYR1 Ca2+ release during EC coupling that results from the mutation producing a dominant-negative suppression of RYR1 channel Ca2+ ion permeation.

scholarly journals Type 1 ryanodine receptor knock-in mutation causing central core disease of skeletal muscle also displays a neuronal phenotype

2011 ◽  
Vol 109 (2) ◽  
pp. 610-615 ◽  
Author(s):  
V. De Crescenzo ◽  
K. E. Fogarty ◽  
J. J. Lefkowitz ◽  
K. D. Bellve ◽  
E. Zvaritch ◽  
...  
Keyword(s):  
Skeletal Muscle ◽  
Ryanodine Receptor ◽  
Central Core ◽  
Central Core Disease ◽  
Neuronal Phenotype

scholarly journals Central core disease mutations R4892W, I4897T and G4898E in the ryanodine receptor isoform 1 reduce the Ca2+ sensitivity and amplitude of Ca2+-dependent Ca2+ release

2004 ◽  
Vol 382 (2) ◽  
pp. 557-564 ◽  
Author(s):  
Guo Guang DU ◽  
Vijay K. KHANNA ◽  
Xinghua GUO ◽  
David H. MacLENNAN
Keyword(s):  
Ryanodine Receptor ◽  
Central Core ◽  
Central Core Disease ◽  
Peak Amplitude ◽  
Wild Type ◽  
Release Channel ◽  
Hek 293 ◽  
Disease Mutations ◽  
293 Cells ◽  
Ryanodine Receptor 1

Three CCD (central core disease) mutants, R4892W (Arg4892→Trp), I4897T and G4898E, in the pore region of the skeletal-muscle Ca2+-release channel RyR1 (ryanodine receptor 1) were characterized using a newly developed assay that monitored Ca2+ release in the presence of Ca2+ uptake in microsomes isolated from HEK-293 cells (human embryonic kidney 293 cells), co-expressing each of the three mutants together with SERCA1a (sarcoplasmic/endoplasmic-reticulum Ca2+-ATPase 1a). Both Ca2+ sensitivity and peak amplitude of Ca2+ release were either absent from or sharply decreased in homotetrameric mutants. Co-expression of wild-type RyR1 with mutant RyR1 (heterotetrameric mutants) restored Ca2+ sensitivity partially, in the ratio 1:2, or fully, in the ratio 1:1. Peak amplitude was restored only partially in the ratio 1:2 or 1:1. Reduced amplitude was not correlated with maximum Ca2+ loading or the amount of expressed RyR1 protein. High-affinity [3H]ryanodine binding and caffeine-induced Ca2+ release were also absent from the three homotetrameric mutants. These results indicate that decreased Ca2+ sensitivity is one of the serious defects in these three excitation–contraction uncoupling CCD mutations. In CCD skeletal muscles, where a mixture of wild-type and mutant RyR1 is expressed, these defects are expected to decrease Ca2+-induced Ca2+ release, as well as orthograde Ca2+ release, in response to transverse tubular membrane depolarization.

Sign in / Sign up

Export Citation Format

Share Document