Disease relevance of RYR1

• Mutations in the ryanodine receptor gene in central core disease and malignant hyperthermia [1].
• A mutation in the human ryanodine receptor gene associated with central core disease [2].
• Linkage was demonstrated between the locus for F18 E. coli receptors and the loci S, RYR1, GPI, EAH, A1BG and PGD (Z > 20) [3].
• The RYR1 g.1843C>T mutation is associated with the effect of the IGF2 intron3-g.3072G>A mutation on muscle hypertrophy [4].
• We report a German MH pedigree where in vitro contracture test (IVCT) results and haplotypes of markers for the MHS1/RYR1 region including this base transition have yielded several discrepancies [5].

High impact information on RYR1

• In porcine MH, these studies identified the skeletal muscle sarcoplasmic reticulum Ca2+ release channel gene (RYR1) as the site of the defect [6].
• As a more definitive test of whether the RYR gene is a candidate gene for the human MH phenotype, we have carried out a linkage study with MH families to determine whether the MH phenotype segregates with chromosome 19q markers, including markers in the RYR gene [7].
• Co-segregation of MH with RYR markers, resulting in a lod score of 4.20 at a linkage distance of zero centimorgans, indicates that MH is likely to be caused by mutations in the RYR gene [7].
• Abnormalities in the Ca2+ release channel of skeletal muscle sarcoplasmic reticulum (the ryanodine receptor) have been implicated in the cause of both the porcine and human syndromes by physiological and biochemical studies and genetic linkage analysis [8].
• A single point mutation in the porcine gene for the skeletal muscle ryanodine receptor (ryr1) was found to be correlated with MH in five major breeds of lean, heavily muscled swine [9].

Chemical compound and disease context of RYR1

• The substitutions of T for C1843 in the porcine ryanodine receptor (RYR1) gene, which deletes a HinPI restriction endonuclease site and creates a HgiAI site, and of T for C1840 in human RYR1, which deletes a RsaI site, lead to Cys for Arg substitutions in the ryanodine receptors and are probable causal mutations for malignant hyperthermia (MH) [10].
• In the present report we show that the presence of the Arg-to-Cys point mutation in the recombinant RYR expressed in COS-7 transfected cells causes abnormal cytosolic Ca2+ transients in response to 4-chloro-m-cresol, an agent capable of eliciting in vitro contracture of MH-susceptible muscles [11].
• The effect of peptides, corresponding to sequences in the skeletal muscle dihydropyridine receptor II-III loop, on Ca(2+) release from sarcoplasmic reticulum (SR) and on ryanodine receptor (RyR) calcium release channels have been compared in preparations from normal and malignant hyperthermia (MH)-susceptible pigs [12].
• Inhibition of calcium-release channel (ryanodine receptor) opening by administration of dantrolene prevented the increase in intracytoplasmic calcium (159 +/- 8 versus 234 +/- 18 nM, p < 0.05) and partially ameliorated systolic and diastolic ventricular dysfunction [13].
• BACKGROUND: Recent work suggests that impaired Mg(2+) regulation of the ryanodine receptor is a common feature of both pig and human malignant hyperthermia [14].

Biological context of RYR1

• We screened a porcine bacterial artificial chromosome (BAC) and a P1 derived artificial chromosome (PAC) library to construct a sequence-ready approximately 1.2-Mb BAC/PAC contig of the ryanodine receptor-1 gene (RYR1) region on porcine chromosome (SSC) 6q1 [15].
• In this report, we describe the genomic organization of a 15.5-kb genomic fragment comprising 18 exons coding for region 4624 to 7929 of the porcine skeletal muscle ryanodine receptor gene [16].
• The coefficients of correlation for the Nn genotype of the RYR1 gene between the values after slaughter and both the first and the second biopsy for pH1 and EC50 were very low (r = 0.06, r = 0.14; and r = 0.26, r = 0.26; P ? 0.05) [17].
• Our data suggest that (i) RYR1 gene expression is regulated by at least two novel transcription factors (designated RYREF-1 and RYREF-2), and (ii) tissue specificity results from a transcriptional repression in nonmuscle cells mediated by the first intron [18].
• Missense mutation analysis indicates that the Lys and Arg residues are essential for calmodulin binding to the synthetic peptide RYR1 PM3 [19].

Anatomical context of RYR1

• Genomic organization of the porcine skeletal muscle ryanodine receptor (RYR1) gene coding region 4624 to 7929 [16].
• Calcium is released from the terminal cisternae of the sarcoplasmic reticulum via the ryanodine receptor [16].
• Although, the skeletal muscle isoform (RYR1) was shown to be expressed predominantly in skeletal muscle, expression was also detected in the esophagus and brain [18].
• To analyze the transcriptional regulation of the RYR1 gene, we have constructed chimeric genes composed of the upstream region of the RYR1 gene and the bacterial chloramphenicol acetyltransferase (CAT) gene and transiently transfected them into primary cultured porcine myoblasts, myotubes, and fibroblasts [18].
• IVM media, oocyte diameter and donor genotype at RYR1 locus in relation to the incidence of porcine diploid oocytes after maturation in vitro [20].

Associations of RYR1 with chemical compounds

• Direct detection of calmodulin tuning by ryanodine receptor channel targets using a Ca2+-sensitive acrylodan-labeled calmodulin [21].
• The substitution of thymine for cytosine at position 1840 of the RYR1 transcript results in a cysteine-for-arginine substitution at position 614 (R614C) of the amino acid sequence [22].
• The best conditions for detecting the point mutation were by using a 5% polyacrylamide gel without glycerol and loading at 3 degrees C. The RYR1 genotypes diagnosed by PCR-SSCP were identical to the genotypes diagnosed by restriction enzyme fragment length polymorphism in all cases examined (n = 606) [23].
• This study investigated the possible interactions between the genotypes of the RYR1 and IGF2 QTN on IGF2 expression [4].
• A method allowing simultaneous genotyping of two loci: ryanodine receptor 1 (RYR1) and estrogen receptor (ESR) is presented [24].

Enzymatic interactions of RYR1

• In skeletal muscle SR, however, the level of cAMP-PK or calmodulin catalyzed phosphorylation of the intact ryanodine receptor (0.2 or 2.9 pmol Pi/mg SR, respectively) was much less than the [3H]ryanodine binding activity of this fraction (11.6 pmol/mg) [25].

Regulatory relationships of RYR1

• Unexpectedly, simultaneous blockade of InsP3 receptor and ryanodine receptor (RyR) by 2-APB and ryanodine enhanced SP-evoked muscle contraction and Ca2+ mobilization [26].

Other interactions of RYR1

• Regulation of the RYR1 and RYR2 Ca2+ release channel isoforms by Ca2+-insensitive mutants of calmodulin [27].
• One YAC clone harboring parts of the porcine cardiac muscle ryanodine receptor (RYR2) gene allowed us to assign this locus to Chromosome (Chr) 14q22-q23 [28].

Analytical, diagnostic and therapeutic context of RYR1

• This population allowed us to narrow the genetic region harbouring the affected gene(s) and to demonstrate that the region was confined between RYR1 and SW782 (5.7 cM on the National Institute of Animal Industry (NIAI) map and 100 cR on the INRA/University of Minnesota porcine radiation hybrid panel map) [29].
• In multiplex PCR amplification, two amplicons were simultaneously produced: a 272 bp fragment of RYR1 gene and a 185 bp fragment of ESR gene and were then subjected to "one-tube" restriction enzyme digestion with Hin6 I and Ava I, respectively [24].
• The tissue distribution of mRNA for ryanodine receptor (ryr) isoforms in various porcine tissues has been determined using the reverse transcription-polymerase chain reaction (RT-PCR) [30].
• The specific amplification of each of the ryr isoforms was confirmed by restriction enzyme mapping and DNA sequencing [30].
• Immunoprecipitation of solubilized, [(3)H]azidodantrolene-photolabeled SR protein reveals that the cleaved 160/172 kDa protein remains associated with the C-terminal, 410 kDa portion of the RyR [31].

References