Published In

JCI Insight

Document Type

Post-Print

Publication Date

2019

Subjects

Muscles -- Molecular aspects, Muscles -- Physiology, Neuromuscular diseases -- Animal models, Ubiquitin

Abstract

Nemaline myopathy is a congenital neuromuscular disorder characterized by muscle weakness, fiber atrophy, and presence of nemaline bodies within myofibers. However, understanding of the underlying pathomechanisms is lacking. Recently, mutations in KBTBD13, KLHL40, and KLHL41, three substrate adaptors for the E3 ubiquitin ligase Cullin-3, have been associated with early-onset nemaline myopathies. We hypothesized that deregulation of Cullin-3 and its muscle protein substrates may be responsible for disease development. Using Cullin-3–knockout mice, we identified accumulation of non-muscle α-actinins (ACTN1 and ACTN4) in muscles of these mice, which we also observed in patients with mutations in KBTBD13. Our data reveal that proper regulation of Cullin-3 activity and ACTN1 levels is essential for normal muscle and neuromuscular junction development. While ACTN1 is naturally downregulated during myogenesis, its overexpression in C2C12 myoblasts triggered defects in fusion, myogenesis, and acetylcholine receptor clustering — features that we characterized in Cullin-3–deficient mice. Taken together, our data highlight the importance of Cullin-3–mediated degradation of ACTN1 for muscle development, and indicate what is to our knowledge new pathomechanism for the etiology of myopathies seen in Cullin-3–knockout mice and patients with nemaline myopathy.

Description

This is the author's accepted manuscript of an article that subsequently appeared in JCI Insight, vol. 4, no. 10, published by the American Society for Clinical Investigation. The version of record may be found at https://dx.doi.org/10.1172%2Fjci.insight.125665.

DOI

10.1172/jci.insight.125665

Persistent Identifier

https://archives.pdx.edu/ds/psu/29664

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