Acute and chronic tirasemtiv treatment improves in vivo and in vitro muscle performance in actin-based nemaline myopathy mice.

Abstract

Nemaline myopathy, a disease of the actin-based thin filament, is one of the most frequent congenital myopathies. To date, no specific therapy is available to treat muscle weakness in nemaline myopathy. We tested the ability of tirasemtiv, a fast skeletal troponin activator that targets the thin filament, to augment muscle force-both in vivo and in vitro-in a nemaline myopathy mouse model with a mutation (H40Y) in Acta1. In Acta1H40Y mice, treatment with tirasemtiv increased the force response of muscles to submaximal stimulation frequencies. This resulted in a reduced energetic cost of force generation, which increases the force production during a fatigue protocol. The inotropic effects of tirasemtiv were present in locomotor muscles and, albeit to a lesser extent, in respiratory muscles, and they persisted during chronic treatment, an important finding as respiratory failure is the main cause of death in patients with congenital myopathy. Finally, translational studies on permeabilized muscle fibers isolated from a biopsy of a patient with the ACTA1H40Y mutation revealed that at physiological Ca2+ concentrations, tirasemtiv increased force generation to values that were close to those generated in muscle fibers of healthy subjects. These findings indicate the therapeutic potential of fast skeletal muscle troponin activators to improve muscle function in nemaline myopathy due to the ACTA1H40Y mutation, and future studies should assess their merit for other forms of nemaline myopathy and for other congenital myopathies.

• Authors: Josine M de Winter, Charlotte Gineste, Elisa Minardi, Lorenza Brocca, Maira Rossi, Tamara Borsboom, Alan H Beggs, Monique Bernard, David Bendahan, Darren T Hwee, Fady I Malik, Maria Antonietta Pellegrino, Roberto Bottinelli, Julien Gondin, Coen A C Ottenheijm
• Journal: Human molecular genetics (Hum Mol Genet) Vol. 30 Issue 14 Pg. 1305-1320 (06 26 2021) ISSN: 1460-2083 [Electronic] England
• PMID: 33909041 (Publication Type: Journal Article, Research Support, N.I.H., Extramural, Research Support, Non-U.S. Gov't)
• Copyright: © The Author(s) 2021. Published by Oxford University Press. All rights reserved. For Permissions, please email: [email protected].

Chemical References

• Actins
• CK-2017357
• Imidazoles
• Pyrazines

Topics

• Actins (genetics)
• Animals
• Humans
• Imidazoles
• Mice
• Muscle, Skeletal (pathology)
• Mutation
• Myopathies, Nemaline (drug therapy, genetics)
• Pyrazines (therapeutic use)