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Benucci S, Ruiz A, Franchini M, Ruggiero L, Zoppi D, Sitsapesan R, Lindsay C, Pelczar P, Pietrangelo L, Protasi F, Treves S, Zorzato F. A novel, patient-derived RyR1 mutation impairs muscle function and calcium homeostasis in mice. J Gen Physiol 2024; 156:e202313486. [PMID: 38445312 PMCID: PMC10911087 DOI: 10.1085/jgp.202313486] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/14/2023] [Revised: 12/20/2023] [Accepted: 02/09/2024] [Indexed: 03/07/2024] Open
Abstract
RYR1 is the most commonly mutated gene associated with congenital myopathies, a group of early-onset neuromuscular conditions of variable severity. The functional effects of a number of dominant RYR1 mutations have been established; however, for recessive mutations, these effects may depend on multiple factors, such as the formation of a hypomorphic allele, or on whether they are homozygous or compound heterozygous. Here, we functionally characterize a new transgenic mouse model knocked-in for mutations identified in a severely affected child born preterm and presenting limited limb movement. The child carried the homozygous c.14928C>G RYR1 mutation, resulting in the p.F4976L substitution. In vivo and ex vivo assays revealed that homozygous mice fatigued sooner and their muscles generated significantly less force compared with their WT or heterozygous littermates. Electron microscopy, biochemical, and physiological analyses showed that muscles from RyR1 p.F4976L homozygous mice have the following properties: (1) contain fewer calcium release units and show areas of myofibrillar degeneration, (2) contain less RyR1 protein, (3) fibers show smaller electrically evoked calcium transients, and (4) their SR has smaller calcium stores. In addition, single-channel recordings indicate that RyR1 p.F4976L exhibits higher Po in the presence of 100 μM [Ca2+]. Our mouse model partly recapitulates the clinical picture of the homozygous human patient and provides significant insight into the functional impact of this mutation. These results will help understand the pathology of patients with similar RYR1 mutations.
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Affiliation(s)
- Sofia Benucci
- Departments of Biomedicine and Neurology, Basel University Hospital, Basel, Switzerland
| | - Alexis Ruiz
- Departments of Biomedicine and Neurology, Basel University Hospital, Basel, Switzerland
| | - Martina Franchini
- Departments of Biomedicine and Neurology, Basel University Hospital, Basel, Switzerland
| | - Lucia Ruggiero
- Dipartimento di Neuroscienze, Scienze Riproduttive ed Odontostomatologiche, Università degli Studi di Napoli Federico II, Napoli, Italy
| | - Dario Zoppi
- Dipartimento di Neuroscienze, Scienze Riproduttive ed Odontostomatologiche, Università degli Studi di Napoli Federico II, Napoli, Italy
| | | | - Chris Lindsay
- Department of Pharmacology, University of Oxford, Oxford, UK
| | - Pawel Pelczar
- Center for Transgenic Models, University of Basel, Basel, Switzerland
| | - Laura Pietrangelo
- DMSI, Department of Medicine and Aging Sciences and CAST, Center for Advanced Studies and Technology, University G. d’Annunzio of Chieti-Pescara, Chieti, Italy
| | - Feliciano Protasi
- DMSI, Department of Medicine and Aging Sciences and CAST, Center for Advanced Studies and Technology, University G. d’Annunzio of Chieti-Pescara, Chieti, Italy
| | - Susan Treves
- Departments of Biomedicine and Neurology, Basel University Hospital, Basel, Switzerland
- Department of Life Science and Biotechnology, University of Ferrara, Ferrara, Italy
| | - Francesco Zorzato
- Departments of Biomedicine and Neurology, Basel University Hospital, Basel, Switzerland
- Department of Life Science and Biotechnology, University of Ferrara, Ferrara, Italy
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