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AuthorSeidel, Monika
Authorde Meritens, Camille Rabesahala
AuthorJohnson, Louisa
AuthorParthimos, Dimitris
AuthorBannister, Mark
AuthorThomas, N Lowri
AuthorOzekhome-Mike, Esizaze
AuthorLai, F Anthony
AuthorZissimopoulos, Spyros
Available date2020-04-22T13:46:22Z
Publication Date2020-02-01
Publication NameCardiovascular Researchen_US
Identifierhttp://dx.doi.org/10.1093/cvr/cvaa043
CitationMonika Seidel, Camille Rabesahala de Meritens, Louisa Johnson, Dimitris Parthimos, Mark Bannister, Nia Lowri Thomas, Esizaze Ozekhome-Mike, Francis Anthony Lai, Spyros Zissimopoulos, Identification of an amino-terminus determinant critical for ryanodine receptor/Ca2+ release channel function, Cardiovascular Research, , cvaa043, https://doi.org/10.1093/cvr/cvaa043
ISSN0008-6363
URIhttp://hdl.handle.net/10576/14315
AbstractThe cardiac ryanodine receptor (RyR2), which mediates intracellular Ca2+ release to trigger cardiomyocyte contraction, participates in development of acquired and inherited arrhythmogenic cardiac disease. This study was undertaken to characterize the network of inter- and intra-subunit interactions regulating the activity of the RyR2 homotetramer. We use mutational investigations combined with biochemical assays to identify the peptide sequence bridging the β8 with β9 strand as the primary determinant mediating RyR2 N-terminus self-association. The negatively-charged side chains of two aspartate residues (D179 and D180) within the β8-β9 loop are crucial for the N-terminal inter-subunit interaction. We also show that the RyR2 N-terminus domain interacts with the C-terminal channel pore region in a Ca2+-independent manner. The β8-β9 loop is required for efficient RyR2 subunit oligomerization but it is dispensable for N-terminus interaction with C-terminus. Deletion of the β8-β9 sequence produces unstable tetrameric channels with subdued intracellular Ca2+ mobilization implicating a role for this domain in channel opening. The arrhythmia-linked R176Q mutation within the β8-β9 loop decreases N-terminus tetramerization but does not affect RyR2 subunit tetramerization or the N-terminus interaction with C-terminus. RyR2R176Q is a characteristic hypersensitive channel displaying enhanced intracellular Ca2+ mobilization suggesting an additional role for the β8-β9 domain in channel closing. These results suggest that efficient N-terminus inter-subunit communication mediated by the β8-β9 loop may constitute a primary regulatory mechanism for both RyR2 channel activation and suppression. Our findings that the RyR2 β8-β9 loop is involved in both Ca2+ release channel opening and closing have important clinical implications. This RyR2 domain is a known "hot-spot" for mutations associated with arrhythmogenic cardiac disease, which could produce hypersensitive as well as hyposensitive channels. Therapeutic strategies currently focus on gain-of-function RyR2 channels to suppress sarcoplasmic reticulum Ca2+ release either indirectly with class I/II anti-arrhythmic drugs, or by directly targeting RyR2 to inhibit channel activity. These strategies may not only be ineffective, but they may exacerbate the malignant phenotype in the case of loss-of-function RyR2 mutations.
Languagear
PublisherOxford University Press
SubjectArrhythmia
SubjectCalcium signalling
SubjectDisease mechanism
SubjectExcitation-contraction coupling
SubjectRyanodine receptor
TitleIdentification of an amino-terminus determinant critical for ryanodine receptor/Ca2+ release channel function.
TypeArticle
ESSN1755-3245


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