Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UNIPROT:P21817 (RyR1)
 1,154 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Ryanodine receptor 1 (RYR1) gene mutations are associated with central core disease (CCD), multiminicore disease (MmD) and malignant hyperthermia (MH), and have been reported to be responsible for 47-67% of patients with CCD and rare cases with MmD. However, to date, the true frequency and distribution of the mutations along the RYR1 gene have not been determined yet, since mutation screening has been limited to three 'hot spots', with particular attention to the C-terminal region. In this study, 27 unrelated Japanese CCD patients were included. Clinical histories and muscle biopsies were carefully reviewed. We sequenced all the 106 exons encoding RYR1 with their flanking exon-intron boundaries, and identified 20 novel and 3 previously reported heterozygous missense mutations in 25 of the 27 CCD patients (93%), which is a much higher mutation detection rate than that perceived previously. Among them, six were located outside the known 'hot spots'. Sixteen of 27 (59%) CCD patients had mutations in the C-terminal 'hot spot'. Three CCD patients had a probable autosomal recessive disease with two heterozygous mutations. Patients with C-terminal mutations had earlier onset and rather consistent muscle pathology characterized by the presence of distinct cores in almost all type 1 fibres, interstitial fibrosis and type 2 fibre deficiency. In contrast, patients with mutations outside the C-terminal region had milder clinical phenotype and harbour more atypical cores in their muscle fibres. We also sequenced two genes encoding RYR1-associated proteins as candidate causative genes for CCD: the 12 kD FK506-binding protein (FKBP12) and the alpha1 subunit of L-type voltage-dependent calcium channel or dihydropyridine receptor (CACNA1S). However, no mutation was found, suggesting that these genes may not, or only rarely, be responsible for CCD. Our results indicate that CCD may be caused by RYR1 mutations in the majority of patients.
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PMID:Central core disease is due to RYR1 mutations in more than 90% of patients. 1662 18

1. Excitation-contraction coupling in skeletal muscle is dependent on a physical interaction between the dihydropyridine receptor (DHPR) and the ryanodine receptor (RyR). 2. A number of peptides derived from the II-III loop region of the DHPR have been shown to be functionally active in stimulating the release of calcium via RyR channels. Their function has been found to correlate with the presence of a basic helical region located at the N-terminus of the II-III loop. 3. The entire recombinant skeletal DHPR II-III loop is an efficient activator of RyR1 and RyR2. 4. The skeletal DHPR II-III loop is comprised of a series of a-helices, but its tertiary structure has been determined to be unstructured and flexible. 5. Fluorescence quenching experiments have been used to identify and measure the binding affinity of the II-III loop with fragments of the RyR.
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PMID:Structural and functional characterization of interactions between the dihydropyridine receptor II-III loop and the ryanodine receptor. 1704 24

We have defined regions of the skeletal muscle ryanodine receptor (RyR1) essential for bidirectional signaling with dihydropyridine receptors (DHPRs) and for the organization of DHPR into tetrad arrays by expressing RyR1-RyR3 chimerae in dyspedic myotubes. RyR1-RyR3 constructs bearing RyR1 residues 1-1681 restored wild-type DHPR tetrad arrays and, in part, skeletal-type excitation-contraction (EC) coupling (orthograde signaling) but failed to enhance DHPR Ca(2+) currents (retrograde signaling) to WT RyR1 levels. Within this region, the D2 domain (amino acids 1272-1455), although ineffective on its own, dramatically enhanced the formation of tetrads and EC coupling rescue by constructs that otherwise are only partially effective. These findings suggest that the orthograde signal and DHPR tetrad formation require the contributions of numerous RyR regions. Surprisingly, we found that RyR3, although incapable of supporting EC coupling or tetrad formation, restored a significant level of Ca(2+) current, revealing a functional interaction with the skeletal muscle DHPR. Thus, our data support the hypotheses that (i) the structural/functional link between RyR1 and the skeletal muscle DHPR requires multiple interacting regions, (ii) the D2 domain of RyR1 plays a key role in stabilizing this interaction, and (iii) a form of retrograde signaling from RyR3 to the DHPR occurs in the absence of direct protein-protein interactions.
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PMID:Bidirectional signaling between calcium channels of skeletal muscle requires multiple direct and indirect interactions. 1717 44

Central core disease (CCD) and multi-minicore disease (MmD) are muscle disorders characterized by foci of mitochondria depletion and sarcomere disorganization ("cores") in muscle fibers. Although core myopathies are the most frequent congenital myopathies, their pathogenesis remains elusive and specific diagnostic markers are lacking. Core myopathies are mostly caused by mutations in 2 sarcoplasmic reticulum proteins: the massive Ca-release channel RyR1 or the selenoprotein N (SelN) of unknown function. To search for distinctive markers and to obtain further pathophysiological insight, we identified the molecular defects in 12 core myopathy patients and analyzed the immunolocalization of 6 proteins of the Ca-release complex in their muscle biopsies. In 7 cases with RYR1 mutations (6 CCD, one MmD), RyR1 was depleted from the cores; in contrast, the other proteins of the sarcoplasmic reticulum (calsequestrin, SERCA1/2, and triadin) and the T-tubule (dihydropyridine receptor-alpha1subunit) accumulated within or around the lesions, suggesting an original modification of the Ca-release complex protein arrangement. Conversely, all Ca-related proteins were distributed normally in 5 MmD cases with SelN mutations. Our results provide an appropriate tool to orientate the differential and molecular diagnosis of core myopathies and suggest that different pathophysiological mechanisms lead to core formation in SelN- and in RyR1-related core myopathies.
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PMID:Abnormal distribution of calcium-handling proteins: a novel distinctive marker in core myopathies. 1720 37

In skeletal muscle, the dihydropyridine receptor (DHPR) in the plasma membrane (PM) serves as a Ca(2+) channel and as the voltage sensor for excitation-contraction (EC coupling), triggering Ca(2+) release via the type 1 ryanodine receptor (RyR1) in the sarcoplasmic reticulum (SR) membrane. In addition to being functionally linked, these two proteins are also structurally linked to one another, but the identity of these links remains unknown. As an approach to address this issue, we have expressed DHPR alpha(1S) or beta(1a) subunits, with a biotin acceptor domain fused to targeted sites, in myotubes null for the corresponding, endogenous DHPR subunit. After saponin permeabilization, the approximately 60-kD streptavidin molecule had access to the beta(1a) N and C termini and to the alpha(1S) N terminus and proximal II-III loop (residues 671-686). Steptavidin also had access to these sites after injection into living myotubes. However, sites of the alpha(1S) C terminus were either inaccessible or conditionally accessible in saponin- permeabilized myotubes, suggesting that these C-terminal regions may exist in conformations that are occluded by other proteins in PM/SR junction (e.g., RyR1). The binding of injected streptavidin to the beta(1a) N or C terminus, or to the alpha(1S) N terminus, had no effect on electrically evoked contractions. By contrast, binding of streptavidin to the proximal alpha(1S) II-III loop abolished such contractions, without affecting agonist-induced Ca(2+) release via RyR1. Moreover, the block of EC coupling did not appear to result from global distortion of the DHPR and supports the hypothesis that conformational changes of the alpha(1S) II-III loop are necessary for EC coupling in skeletal muscle.
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PMID:Accessibility of targeted DHPR sites to streptavidin and functional effects of binding on EC coupling. 1789 91

Conformational coupling between the L-type voltage-gated Ca(2+) channel (or 1,4-dihydropyridine receptor; DHPR) and the ryanodine-sensitive Ca(2+) release channel of the sarcoplasmic reticulum (RyR1) is the mechanistic basis for excitation-contraction (EC) coupling in skeletal muscle. In this article, recent findings regarding the roles of the individual cytoplasmic domains (the amino- and carboxyl-termini, cytoplasmic loops I-II, II-III, and III-IV) of the DHPR alpha(1S) subunit in bi-directional communication with RyR1 will be discussed.
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PMID:Bridging the myoplasmic gap: recent developments in skeletal muscle excitation-contraction coupling. 1789 4

A heterozygous Ile4898 to Thr (I4898T) mutation in the human type 1 ryanodine receptor/Ca(2+) release channel (RyR1) leads to a severe form of central core disease. We created a mouse line in which the corresponding Ryr1(I4895T) mutation was introduced by using a "knockin" protocol. The heterozygote does not exhibit an overt disease phenotype, but homozygous (IT/IT) mice are paralyzed and die perinatally, apparently because of asphyxia. Histological analysis shows that IT/IT mice have greatly reduced and amorphous skeletal muscle. Myotubes are small, nuclei remain central, myofibrils are disarranged, and no cross striation is obvious. Many areas indicate probable degeneration, with shortened myotubes containing central stacks of pyknotic nuclei. Other manifestations of a delay in completion of late stages of embryogenesis include growth retardation and marked delay in ossification, dermatogenesis, and cardiovascular development. Electron microscopy of IT/IT muscle demonstrates appropriate targeting and positioning of RyR1 at triad junctions and a normal organization of dihydropyridine receptor (DHPR) complexes into RyR1-associated tetrads. Functional studies carried out in cultured IT/IT myotubes show that ligand-induced and DHPR-activated RyR1 Ca(2+) release is absent, although retrograde enhancement of DHPR Ca(2+) conductance is retained. IT/IT mice, in which RyR1-mediated Ca(2+) release is abolished without altering the formation of the junctional DHPR-RyR1 macromolecular complex, provide a valuable model for elucidation of the role of RyR1-mediated Ca(2+) signaling in mammalian embryogenesis.
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PMID:An Ryr1I4895T mutation abolishes Ca2+ release channel function and delays development in homozygous offspring of a mutant mouse line. 1800 98

This study aimed to clarify changes in the spatial expressions of types 1, 2 and 3 ryanodine receptors (RyR1, RyR2 and RyR3) in the cerebellum of a Ca(2+) channel alpha(1A) subunit mutant, rolling mouse Nagoya. Semi-quantitative reverse transcription-polymerase chain reaction (RT-PCR) revealed that the mRNA signal levels of RyR1 and RyR3 were altered in the rolling cerebellum, which exhibited lower densities of RyR1 bands and higher densities of RyR3 bands than in the control cerebellum. Quite consistent with the RT-PCR results, the staining intensity of RyR1 and RyR3 was altered in the rolling cerebellum. RyR1 immunostaining appeared in somata and the proximal dendrites of Purkinje cells, and the staining intensity of both subcellular regions was equally lower in all cerebellar lobules of rolling mice than in those of controls. Although RyR3 immunostaining appeared in the dendrites of granule cells, more intense RyR3 staining in rolling mice than in controls was uniformly observed throughout all cerebellar lobules. The present study further examined co-localizations of ryanodine receptor subtypes and voltage-gated Ca(2+) channel alpha(1) subunits in the rolling cerebellum. Somatodendritic RyR1 immunostaining in Purkinje cells overlapped with either a mutated Ca(2+) channel alpha(1A) subunit (P/Q-type), or a Ca(2+) channel alpha(1C) subunit (L-type; dihydropyridine receptor) immunostaining. Immunostaining of these alpha(1) subunits also emerged in granule cells. Those results suggest non-region-related alterations in RyR1 and RyR3 expressions in the rolling mouse cerebellum. Such expressional changes in ryanodine receptor subtypes may be involved in Ca(2+) channel alpha(1A) subunit gene mutation, and may alter regulation of intracellular Ca(2+) concentrations in cerebellar cortical neurons.
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PMID:Differential alterations in expressions of ryanodine receptor subtypes in cerebellar cortical neurons of an ataxic mutant, rolling mouse Nagoya. 1831 30

In skeletal muscle, coupling between the 1,4-dihydropyridine receptor (DHPR) and the type 1 ryanodine receptor (RyR1) underlies excitation-contraction (EC) coupling. The III-IV loop of the DHPR alpha(1S) subunit binds to a segment of RyR1 in vitro, and mutations in the III-IV loop alter the voltage dependence of EC coupling, raising the possibility that this loop is directly involved in signal transmission from the DHPR to RyR1. To clarify the role of the alpha(1S) III-IV loop in EC coupling, we examined the functional properties of a chimera (GFP-alpha(1S)[III-IVa]) in which the III-IV loop of the divergent alpha(1A) isoform replaced that of alpha(1S). Dysgenic myotubes expressing GFP-alpha(1S)[III-IVa] yielded myoplasmic Ca(2+) transients that activated at approximately 10 mV more hyperpolarized potentials and that were approximately 65% smaller than those of GFP-alpha(1S). A similar reduction was observed in voltage-dependent charge movements for GFP-alpha(1S)[III-IVa], indicating that the chimeric channels trafficked less well to the membrane but that those that were in the membrane functioned as efficiently in EC coupling as GFP-alpha(1S). Relative to GFP-alpha(1S), L-type currents mediated by GFP-alpha(1S)[III-IVa] were approximately 40% smaller and activated at approximately 5 mV more hyperpolarized potentials. The altered gating of GFP-alpha(1S)[III-IVa] was accentuated by exposure to +/-Bay K 8644, which caused a much larger hyperpolarizing shift in activation compared with its effect on GFP-alpha(1S). Taken together, our observations indicate that the alpha(1S) III-IV loop is not directly involved in EC coupling but does influence DHPR gating transitions important both for EC coupling and activation of L-type conductance.
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PMID:The alpha(1S) III-IV loop influences 1,4-dihydropyridine receptor gating but is not directly involved in excitation-contraction coupling interactions with the type 1 ryanodine receptor. 1855 50

The II-III loop of the dihydropyridine receptor (DHPR) alpha(1s) subunit is a modulator of the ryanodine receptor (RyR1) Ca(2+) release channel in vitro and is essential for skeletal muscle contraction in vivo. Despite its importance, the structure of this loop has not been reported. We have investigated its structure using a suite of NMR techniques which revealed that the DHPR II-III loop is an intrinsically unstructured protein (IUP) and as such belongs to a burgeoning structural class of functionally important proteins. The loop does not possess a stable tertiary fold: it is highly flexible, with a strong N-terminal helix followed by nascent helical/turn elements and unstructured segments. Its residual structure is loosely globular with the N and C termini in close proximity. The unstructured nature of the II-III loop may allow it to easily modify its interaction with RyR1 following a surface action potential and thus initiate rapid Ca(2+) release and contraction. The in vitro binding partner for the II-III was investigated. The II-III loop interacts with the second of three structurally distinct SPRY domains in RyR1, whose function is unknown. This interaction occurs through two preformed N-terminal alpha-helical regions and a C-terminal hydrophobic element. The A peptide corresponding to the helical N-terminal region is a common probe of RyR function and binds to the same SPRY domain as the full II-III loop. Thus the second SPRY domain is an in vitro binding site for the II-III loop. The possible in vivo role of this region is discussed.
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PMID:A dihydropyridine receptor alpha1s loop region critical for skeletal muscle contraction is intrinsically unstructured and binds to a SPRY domain of the type 1 ryanodine receptor. 1876 Nov 2


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