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KBTBD13 and the ever-expanding sarcomeric universe.
Stuart G Campbell1, Steven A Niederer2
1Departments of Biomedical Engineering and Cellular and Molecular Physiology, Yale University, New Haven, USA.
The Journal of Clinical Investigation
|January 7, 2020
Summary
KBTBD13 protein binds actin in muscle sarcomeres. A mutation linked to nemaline myopathy increases thin-filament stiffness, reducing muscle force and slowing relaxation.
Area of Science:
- Muscle physiology
- Sarcomere biology
- Protein-actin interactions
Background:
- KBTBD13 is a protein found in striated muscle with an unknown function.
- Nemaline myopathy is a muscle disorder characterized by weakness and hypotonia.
Purpose of the Study:
- To investigate the function of KBTBD13 in striated muscle.
- To determine the role of KBTBD13 in sarcomere structure and function.
- To elucidate the impact of a KBTBD13 mutation on muscle contractility.
Main Methods:
- Immunofluorescence to determine KBTBD13 localization within the sarcomere.
- Co-immunoprecipitation to assess KBTBD13's binding to actin.
- In vitro assays to measure the effects of KBTBD13 and its mutation on actin filament properties.
- Measurement of muscle contractile force and relaxation rates.
Main Results:
- KBTBD13 localizes to the sarcomere and directly binds to actin.
- A mutation in KBTBD13 (KBTBD13R408C), associated with nemaline myopathy, alters its interaction with actin.
- This mutation increases thin-filament stiffness, leading to reduced contractile force and slower relaxation rates.
Conclusions:
- KBTBD13 is a novel sarcomeric protein that modulates actin dynamics.
- Dysfunctional KBTBD13, due to specific mutations, contributes to nemaline myopathy pathogenesis by impairing muscle contractility.
- Computational modeling can aid in interpreting functional data related to muscle proteins.
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