title: Two central core disease (CCD) deletions in the C-terminal region of RYR1 alter muscle excitation-contraction (EC) coupling by distinct mechanisms.
abstract: Central core disease (CCD) and malignant hyperthermia (MH) are skeletal muscle disorders that are linked to mutations in the gene that encodes the type 1 ryanodine receptor (RYR1). The RYR1 ion channel plays a central role in excitation-contraction (EC) coupling by releasing Ca(2+) from an internal store. Pathogenic CCD mutations in RYR1 result in changes in the magnitude of Ca(2+) release during EC coupling. CCD has recently been linked to two novel deletions (c.12640_12648delCGCCAGTTC [p.Arg4214_Phe4216del] and c.14779_14784delGTCATC [p.Val4927_Ile4928del]) in the C-terminal region of RYR1. To determine the phenotypic consequences of these mutations and extend our understanding of the pathogenic mechanisms that underlie CCD, we determined functional effects on Ca(2+) release channel activity of analogous deletions (p.Arg4215_Phe4217del and p.Val4926_Ile4927del) engineered into rabbit RYR1 following expression in RYR1-null (dyspedic) myotubes and HEK293 cells. In addition, we assessed effects of the p.Arg4214 Phe4216del mutation on RYR1 function in lymphoblastoid cells obtained from CCD patients heterozygous for the mutation. Here we report that both deletions significantly reduce Ca(2+) release following RYR1 activation, but by different mechanisms. While the p.Arg4214_Phe4216del deletion promotes Ca(2+) depletion from intracellular stores by exhibiting a classic "leaky channel" behavior, the p.Val4927_Ile4928del deletion reduces Ca(2+) release by disrupting Ca(2+) gating and eliminating Ca(2+) permeation through the open channel.
authors.affiliation: Department of Physiology and Pharmacology, University of Rochester, Rochester, New York 14642, USA.
authors.forename: Alla D
authors.initials: AD
authors.lastname: Lyfenko
authors.forename: Sylvie
authors.initials: S
authors.lastname: Ducreux
authors.forename: Ying
authors.initials: Y
authors.lastname: Wang
authors.forename: Le
authors.initials: L
authors.lastname: Xu
authors.forename: Francesco
authors.initials: F
authors.lastname: Zorzato
authors.forename: Ana
authors.initials: A
authors.lastname: Ferreiro
authors.forename: Gerhard
authors.initials: G
authors.lastname: Meissner
authors.forename: Susan
authors.initials: S
authors.lastname: Treves
authors.forename: Robert T
authors.initials: RT
authors.lastname: Dirksen
mesh_terms: D000818:Animals; D000831:Animals, Newborn; D002118:Calcium / Q000378:metabolism; D002478:Cells, Cultured; D004558:Electric Stimulation / Q000379:methods; D004594:Electrophysiology / Q000379:methods; D017353:Gene Deletion; D006801:Humans; D007473:Ion Channels / Q000502:physiology; D017136:Ion Transport / Q000502:physiology; D007962:Leukocytes / Q000378:metabolism / Q000502:physiology; D051379:Mice; D018345:Mice, Knockout; D009119:Muscle Contraction / Q000502:physiology*; D020512:Myopathy, Central Core / Q000235:genetics*; D017434:Protein Structure, Tertiary / Q000235:genetics; D011817:Rabbits; D019837:Ryanodine Receptor Calcium Release Channel / Q000235:genetics* / Q000502:physiology
chemical_list: D007473:Ion Channels; D019837:Ryanodine Receptor Calcium Release Channel; D002118:Calcium