scholarly journals Structural and functional properties of ryanodine receptor type 3 in zebrafish tail muscle

2015 ◽  
Vol 145 (3) ◽  
pp. 173-184 ◽  
Author(s):  
Stefano Perni ◽  
Kurt C. Marsden ◽  
Matias Escobar ◽  
Stephen Hollingworth ◽  
Stephen M. Baylor ◽  
...  
Keyword(s):  
Ryanodine Receptor ◽  
Muscle Fibers ◽  
Complete Disappearance ◽  
Cell Stage ◽  
Release Channel ◽  
Functional Roles ◽  
Ec Coupling ◽  
Structural And Functional Properties ◽  
Fast Twitch ◽  
Type 3

The ryanodine receptor (RyR)1 isoform of the sarcoplasmic reticulum (SR) Ca2+ release channel is an essential component of all skeletal muscle fibers. RyR1s are detectable as “junctional feet” (JF) in the gap between the SR and the plasmalemma or T-tubules, and they are required for excitation–contraction (EC) coupling and differentiation. A second isoform, RyR3, does not sustain EC coupling and differentiation in the absence of RyR1 and is expressed at highly variable levels. Anatomically, RyR3 expression correlates with the presence of parajunctional feet (PJF), which are located on the sides of the SR junctional cisternae in an arrangement found only in fibers expressing RyR3. In frog muscle fibers, the presence of RyR3 and PJF correlates with the occurrence of Ca2+ sparks, which are elementary SR Ca2+ release events of the EC coupling machinery. Here, we explored the structural and functional roles of RyR3 by injecting zebrafish (Danio rerio) one-cell stage embryos with a morpholino designed to specifically silence RyR3 expression. In zebrafish larvae at 72 h postfertilization, fast-twitch fibers from wild-type (WT) tail muscles had abundant PJF. Silencing resulted in a drop of the PJF/JF ratio, from 0.79 in WT fibers to 0.03 in the morphants. The frequency with which Ca2+ sparks were detected dropped correspondingly, from 0.083 to 0.001 sarcomere−1 s−1. The few Ca2+ sparks detected in morphant fibers were smaller in amplitude, duration, and spatial extent compared with those in WT fibers. Despite the almost complete disappearance of PJF and Ca2+ sparks in morphant fibers, these fibers looked structurally normal and the swimming behavior of the larvae was not affected. This paper provides important evidence that RyR3 is the main constituent of the PJF and is the main contributor to the SR Ca2+ flux underlying Ca2+ sparks detected in fully differentiated frog and fish fibers.

Expression levels of RyR1 and RyR3 control resting free Ca2+ in skeletal muscle

2005 ◽  
Vol 288 (3) ◽  
pp. C640-C649 ◽  
Author(s):  
Claudio F. Perez ◽  
José R. López ◽  
Paul D. Allen
Keyword(s):  
Skeletal Muscle ◽  
Ryanodine Receptor ◽  
Tibialis Anterior ◽  
Muscle Fibers ◽  
Expression Levels ◽  
Cultured Myotubes ◽  
Increased Sensitivity ◽  
Type 3 ◽  
Different Levels

To better understand the role of the transient expression of ryanodine receptor (RyR) type 3 (RyR3) on Ca2+ homeostasis during the development of skeletal muscle, we have analyzed the effect of expression levels of RyR3 and RyR1 on the overall physiology of cultured myotubes and muscle fibers. Dyspedic myotubes were infected with RyR1 or RyR3 containing virions at 0.2, 0.4, 1.0, and 4.0 moieties of infection (MOI), and analysis of their pattern of expression, caffeine sensitivity, and resting free Ca2+ concentration ([Ca2+]r) was performed. Although increased MOI resulted in increased expression of each receptor isoform, it did not significantly affect the immunopattern of RyRs or the expression levels of calsequestrin, triadin, or FKBP-12. Interestingly, myotubes expressing RyR3 always had significantly higher [Ca2+]r and lower caffeine EC50 than did cells expressing RyR1. Although some of the increased sensitivity of RyR3 to caffeine could be attributed to the higher [Ca2+]r in RyR3-expressing cells, studies of [3H]ryanodine binding demonstrated intrinsic differences in caffeine sensitivity between RyR1 and RyR3. Tibialis anterior (TA) muscle fibers at different stages of postnatal development exhibited a transient increase in [Ca2+]r coordinately with their level of RyR3 expression. Similarly, adult soleus fibers, which also express RyR3, had higher [Ca2+]r than did adult TA fibers, which exclusively express RyR1. These data show that in skeletal muscle, RyR3 increases [Ca2+]r more than RyR1 does at any expression level. These data suggest that the coexpression of RyR1 and RyR3 at different levels may constitute a novel mechanism by which to regulate [Ca2+]r 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.

Eugenol-induced contractions of saponin-skinned fibers are inhibited by heparin or by a ryanodine receptor blocker

2005 ◽  
Vol 83 (12) ◽  
pp. 1093-1100 ◽  
Author(s):  
Marco S. Lofrano-Alves ◽  
Edson L. Oliveira ◽  
Carlos E.N. Damiani ◽  
Ilana Kassouf-Silva ◽  
Rosalvo T.H. Fogaça
Keyword(s):  
Ryanodine Receptor ◽  
Rana Catesbeiana ◽  
Ryanodine Receptors ◽  
Muscle Fibers ◽  
Ruthenium Red ◽  
Muscle Contractions ◽  
Skinned Fibers ◽  
Receptor Blocker ◽  
Release Channel ◽  
Skinned Muscle

The effects of eugenol on the sarcoplasmic reticulum (SR) and contractile apparatus of chemically skinned skeletal muscle fibers of the frog Rana catesbeiana were investigated. In saponin-skinned fibers, eugenol (5 mmol/L) induced muscle contractions, probably by releasing Ca2+ from the SR. The Ca2+-induced Ca2+ release blocker ruthenium red (10 μmol/L) inhibited both caffeine- and eugenol-induced muscle contractions. Ryanodine (200 μmol/L), a specific ryanodine receptor/Ca2+ release channel blocker, promoted complete inhibition of the contractions induced by caffeine, but only partially blocked the contractions induced by eugenol. Heparin (2.5 mg/mL), an inositol 1,4,5-trisphosphate (InsP3) receptor blocker, strongly inhibited the contractions induced by eugenol but had only a small effect on the caffeine-induced contractions. Eugenol neither altered the Ca2+ sensitivity nor the maximal force in Triton X-100 skinned muscle fibers. These data suggest that muscle contraction induced by eugenol involves at least 2 mechanisms of Ca2+ release from the SR: one related to the activation of the ryanodine receptors and another through a heparin-sensitive pathway.

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.

Calmodulin Regulation and Identification of Calmodulin Binding Region of Type-3 Ryanodine Receptor Calcium Release Channel†

Biochemistry ◽  
2005 ◽  
Vol 44 (45) ◽  
pp. 15074-15081 ◽  
Author(s):  
Naohiro Yamaguchi ◽  
Le Xu ◽  
Daniel A. Pasek ◽  
Kelly E. Evans ◽  
S. R. Wayne Chen ◽  
...  
Keyword(s):  
Ryanodine Receptor ◽  
Calcium Release ◽  
Binding Region ◽  
Calcium Release Channel ◽  
Release Channel ◽  
Calmodulin Binding ◽  
Type 3
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