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Updated: Jun 13, 2026
Analysis of Embryonic and Larval Zebrafish Skeletal Myofibers from Dissociated Preparations
Published on: November 13, 2013
Zebrafish MTMR14 is required for excitation-contraction coupling, developmental motor function and the regulation of
J J Dowling1, S E Low, A S Busta
1Department of Pediatrics, University of Michigan Medical Center, Ann Arbor, MI 48109-2200, USA. jamedowl@med.umich.edu
Abstract:
Myotubularins are a family of dual-specificity phosphatases that act to modify phosphoinositides and regulate membrane traffic. Mutations in several myotubularins are associated with human disease. Sequence changes in MTM1 and MTMR14 (also known as Jumpy) have been detected in patients with a severe skeletal myopathy called centronuclear myopathy. MTM1 has been characterized in vitro and in several model systems, while the function of MTMR14 and its specific role in muscle development and disease is much less well understood. We have previously reported that knockdown of zebrafish MTM1 results in significantly impaired motor function and severe histopathologic changes in skeletal muscle that are characteristic of human centronuclear myopathy. In the current study, we examine zebrafish MTMR14 using gene dosage manipulation. As with MTM1 knockdown, morpholino-mediated knockdown of MTMR14 results in morphologic abnormalities, a developmental motor phenotype characterized by diminished spontaneous contractions and abnormal escape response, and impaired excitation-contraction coupling. In contrast to MTM1 knockdown, however, muscle ultrastructure is unaffected. Double knockdown of both MTM1 and MTMR14 significantly impairs motor function and alters skeletal muscle ultrastructure. The combined effect of reducing levels of both MTMR14 and MTM1 is significantly more severe than either knockdown alone, an effect which is likely mediated, at least in part, by increased autophagy. In all, our results suggest that MTMR14 is required for motor function and, in combination with MTM1, is required for myocyte homeostasis and normal embryonic development.
Insights
MTMR14, like MTM1, is crucial for motor function and muscle health. Combined MTM1 and MTMR14 deficiency severely impacts zebrafish development, suggesting a critical role in myocyte homeostasis.
Area of Science:
- Molecular Biology
- Genetics
- Developmental Biology
Background:
- Myotubularins are phosphatases regulating membrane traffic; mutations cause centronuclear myopathy.
- MTM1 is linked to centronuclear myopathy, but MTMR14's role is less understood.
- Zebrafish MTM1 knockdown causes motor deficits and muscle pathology.
Purpose of the Study:
- To investigate the function of MTMR14 in zebrafish development and muscle.
- To compare the effects of MTMR14 and MTM1 knockdown.
- To assess the combined impact of MTM1 and MTMR14 deficiency.
Main Methods:
- Gene dosage manipulation using morpholinos in zebrafish.
- Assessment of motor function, muscle morphology, and excitation-contraction coupling.
- Analysis of muscle ultrastructure and autophagy markers.
Main Results:
- MTMR14 knockdown alone causes motor deficits and impaired excitation-contraction coupling, but not ultrastructural changes.
- Combined MTM1 and MTMR14 knockdown exacerbates motor deficits and alters muscle ultrastructure.
- The synergistic effect of double knockdown is partly mediated by increased autophagy.
Conclusions:
- MTMR14 is essential for motor function in zebrafish.
- MTMR14, alongside MTM1, plays a vital role in myocyte homeostasis and embryonic development.
- Dual deficiency of MTM1 and MTMR14 leads to severe developmental defects, highlighting their cooperative function.
