Zebrafish models for nemaline myopathy reveal a spectrum of nemaline bodies contributing to reduced muscle function

Abstract KLHL40-related nemaline myopathy is a severe autosomal recessive muscle disorder. The current study describes 4 cases of KLHL40-related nemaline myopathy in Hong Kong ethnic Chinese presenting within 3 years, which are confirmed with clinicopathologic features and genetic studies. The incidence is estimated to be at least 1 in 45 226 livebirths (at least 1 in 41 608 among ethnic Chinese livebirths) in Hong Kong. Hyponatremia appears to be another common feature in these patients. Salient histological features include nemaline bodies ranging from 200 to 500 nm in diameters on ultrastructural examination as well as negative KLHL40 immunohistochemistry; type II fiber predominance is obvious in 2 cases. We demonstrate the founder effect associated with genetic variant c.1516A>C (p.Thr506Pro) by polymorphic marker analysis, which revealed a 0.56–0.75-Mb or 0.41–0.78-cM shared haplotype encompassing the disease allele. The mutation is believed to have occurred around 412 generations ago or 6220 BCE, as estimated using DMLE+ and a formula described by Boehnke. We believe the founder variant might possibly underlie a sizable portion of nemaline myopathy in ethnic Chinese. Analysis of the KLHL40 gene may be considered as the first-tier testing of congenital myopathy in this ethnic group.

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Cofilin loss in Drosophila contributes to myopathy through defective sarcomerogenesis and aggregate formation during muscle growth

10.1101/825448 ◽

2019 ◽

Author(s):

Mridula Balakrishnan ◽

Shannon F. Yu ◽

Samantha M. Chin ◽

David B. Soffar ◽

Stefanie E. Windner ◽

...

Keyword(s):

Point Mutation ◽

Muscle Function ◽

Muscle Growth ◽

Nemaline Myopathy ◽

Aggregate Formation ◽

Thin Filaments ◽

Sarcomeric Protein ◽

Thick Filaments

SUMMARYSarcomeres, the fundamental contractile units of muscles, are conserved structures composed of actin thin filaments and myosin thick filaments. How sarcomeres are formed and maintained is not well understood. Here, we show that knockdown of Drosophila Cofilin (DmCFL), an actin depolymerizing factor, leads to the progressive disruption of sarcomere structure and muscle function in vivo. Loss of DmCFL also results in the formation of sarcomeric protein aggregates and impairs sarcomere addition during growth. Strikingly, activation of the proteasome delayed muscle deterioration in our model. Further, we investigate how a point mutation in CFL2 that causes nemaline myopathy (NM) in humans, affects CFL function and leads to the muscle phenotypes observed in vivo. Our data provide significant insights to the role of CFLs during sarcomere formation as well as mechanistic implications for disease progression in NM patients.

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L-tyrosine supplementation is not therapeutic for skeletal muscle dysfunction in zebrafish and mouse models of dominant skeletal muscle α-actin nemaline myopathy

10.1101/218016 ◽

2017 ◽

Cited By ~ 1

Author(s):

Adriana M. Messineo ◽

Charlotte Gineste ◽

Tamar E. Sztal ◽

Elyshia L. McNamara ◽

Christophe Vilmen ◽

...

Keyword(s):

Skeletal Muscle ◽

Animal Models ◽

Mouse Models ◽

Muscle Function ◽

Skeletal Muscles ◽

Nemaline Myopathy ◽

Quadriceps Muscle ◽

Therapeutic Benefit ◽

Skeletal Muscle Function ◽

Tyrosine Concentration

ABSTRACTNemaline myopathy (NM) is a skeletal muscle disorder with no curative treatment. Although L-tyrosine administration has been indicated to provide benefit to patients, previous studies have been limited due to sample size or not testing for raised L-tyrosine levels. We evaluated the efficacy of L-tyrosine treatment to improve skeletal muscle function in three animal models of NM caused by skeletal muscle α-actin (ACTA1) mutations. Firstly we determined the maximum safest L-tyrosine concentration for inclusion in the water of wildtype zebrafish. We then treated NM TgACTA1D286G-eGFP zebrafish from 24 hours post fertilization with the highest safe L-tyrosine dose (10 µM). At 6 days post fertilization, no significant improvement was detected in skeletal muscle function (swimming distance). We also determined the highest safe L-tyrosine dose for dietary L-tyrosine supplementation to wildtype mice. Next we treated the NM TgACTA1D286G mouse model continuously from preconception with 2% L-tyrosine supplemented to regular feed. We examined skeletal muscles at 6–7 weeks using indicators of skeletal muscle integrity: bodyweight, voluntary running wheel and rotarod performance, all parameters previously shown to be reduced in TgACTA1D286G mice. The L-tyrosine treatment regime did not result in any improvement of these parameters, despite significant elevation of free L-tyrosine levels in sera (57%) and quadriceps muscle (45%) of treated TgACTA1D286G mice. Additionally, we assessed the effects of 4 weeks of 2% L-tyrosine dietary supplementation on skeletal muscle function of older (6-7 month old) NM TgACTA1D286G and KIActa1H40Y mice. This dosing regime did not improve decreased bodyweight, nor the mechanical properties, energy metabolism, or atrophy of skeletal muscles in these NM models. Together these findings demonstrate that with the treatment regimes and doses evaluated, L-tyrosine does not therapeutically modulate dysfunctional skeletal muscles in NM animal models with dominant ACTA1 mutations. Therefore this study yields important information on aspects of the clinical utility of L-tyrosine for ACTA1 NM.Summary statementDespite previous encouraging reports, this study utilising zebrafish and mouse models of nemaline myopathy shows no therapeutic benefit on skeletal muscle functionality in response to L-tyrosine supplementation.

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Alterations at the Cross-Bridge Level Are Associated with a Paradoxical Gain of Muscle Function In Vivo in a Mouse Model of Nemaline Myopathy

PLoS ONE ◽

10.1371/journal.pone.0109066 ◽

2014 ◽

Vol 9 (9) ◽

pp. e109066 ◽

Cited By ~ 3

Author(s):

Charlotte Gineste ◽

Coen Ottenheijm ◽

Yann Le Fur ◽

Sébastien Banzet ◽

Emilie Pecchi ◽

...

Keyword(s):

Mouse Model ◽

Muscle Function ◽

Nemaline Myopathy ◽

Cross Bridge ◽

The Cross

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173. The Cardiac Alkali Myosin Light Chain Can Restore Skeletal Muscle Function in a Mouse Model of Nemaline Myopathy

Molecular Therapy ◽

10.1016/s1525-0016(16)34508-7 ◽

2013 ◽

Vol 21 ◽

pp. S68

Keyword(s):

Skeletal Muscle ◽

Mouse Model ◽

Light Chain ◽

Muscle Function ◽

Myosin Light Chain ◽

Nemaline Myopathy ◽

Skeletal Muscle Function

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Multimodal MRI and 31P-MRS Investigations of the ACTA1(Asp286Gly) Mouse Model of Nemaline Myopathy Provide Evidence of Impaired In Vivo Muscle Function, Altered Muscle Structure and Disturbed Energy Metabolism

PLoS ONE ◽

10.1371/journal.pone.0072294 ◽

2013 ◽

Vol 8 (8) ◽

pp. e72294 ◽

Cited By ~ 12

Author(s):

Charlotte Gineste ◽

Guillaume Duhamel ◽

Yann Le Fur ◽

Christophe Vilmen ◽

Patrick J. Cozzone ◽

...

Keyword(s):

Energy Metabolism ◽

Mouse Model ◽

Muscle Function ◽

Nemaline Myopathy ◽

Muscle Structure ◽

31P Mrs ◽

Multimodal Mri

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Combined MRI and 31P-MRS Investigations of the ACTA1(H40Y) Mouse Model of Nemaline Myopathy Show Impaired Muscle Function and Altered Energy Metabolism

PLoS ONE ◽

10.1371/journal.pone.0061517 ◽

2013 ◽

Vol 8 (4) ◽

pp. e61517 ◽

Cited By ~ 12

Author(s):

Charlotte Gineste ◽

Yann Le Fur ◽

Christophe Vilmen ◽

Arnaud Le Troter ◽

Emilie Pecchi ◽

...

Keyword(s):

Energy Metabolism ◽

Mouse Model ◽

Muscle Function ◽

Nemaline Myopathy ◽

31P Mrs

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Alpha-actinin in nemaline bodies in congenital nemaline myopathy: immunological confirmation by light and electron microscopy

Neuromuscular Disorders ◽

10.1016/0960-8966(94)00035-8 ◽

1995 ◽

Vol 5 (2) ◽

pp. 93-104 ◽

Cited By ~ 39

Author(s):

Carina Wallgren-Pettersson ◽

Bharat Jasani ◽

Geoffrey R. Newman ◽

Glenn E. Morris ◽

Sally Jones ◽

...

Keyword(s):

Electron Microscopy ◽

Light And Electron Microscopy ◽

Nemaline Myopathy ◽

Nemaline Bodies

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Clinical course correlates poorly with muscle pathology in nemaline myopathy

Neurology ◽

10.1212/01.wnl.0000046585.81304.bc ◽

2003 ◽

Vol 60 (4) ◽

pp. 665-673 ◽

Cited By ~ 93

Author(s):

M. M. Ryan ◽

B. Ilkovski ◽

C. D. Strickland ◽

C. Schnell ◽

D. Sanoudou ◽

...

Keyword(s):

Electron Microscopy ◽

North American ◽

Fiber Type ◽

Size Variation ◽

Nemaline Myopathy ◽

Clinical Severity ◽

Pathologic Findings ◽

Fiber Size ◽

Nemaline Bodies

Objective: To report pathologic findings in 124 Australian and North American cases of primary nemaline myopathy.Methods: Results of 164 muscle biopsies from 124 Australian and North American patients with primary nemaline myopathy were reviewed, including biopsies from 19 patients with nemaline myopathy due to α-actin (ACTA1) mutations and three with mutations in α-tropomyosinSLOW (TPM3). For each biopsy rod number per fiber, percentage of fibers with rods, fiber-type distribution of rods, and presence or absence of intranuclear rods were documented.Results: Rods were present in all skeletal muscles and diagnosis was possible at all ages. Most biopsies contained nemaline bodies in more than 50% of fibers, although rods were seen only on electron microscopy in 10 patients. Rod numbers and localization correlated poorly with clinical severity. Frequent findings included internal nuclei and increased fiber size variation, type 1 fiber predominance and atrophy, and altered expression of fiber type specific proteins. Marked sarcomeric disruption, increased glycogen deposition, and intranuclear rods were associated with more severe clinical phenotypes. Serial biopsies showed progressive fiber size variation and increasing numbers of rods with time. Pathologic findings varied widely in families with multiple affected members.Conclusions: Very numerous nemaline bodies, glycogen accumulation, and marked sarcomeric disruption were common in nemaline myopathy associated with mutations in skeletal α-actin. Nemaline myopathy due to mutations in α-tropomyosinSLOW was characterized by preferential rod formation in, and atrophy of, type 1 fibers. Light microscopic features of nemaline myopathy correlate poorly with disease course. Electron microscopy may correlate better with disease severity and genotype.

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Abnormal actin binding of aberrant β-tropomyosins is a molecular cause of muscle weakness in TPM2-related nemaline and cap myopathy

Biochemical Journal ◽

10.1042/bj20111030 ◽

2012 ◽

Vol 442 (1) ◽

pp. 231-239 ◽

Cited By ~ 39

Author(s):

Minttu Marttila ◽

Elina Lemola ◽

William Wallefeld ◽

Massimiliano Memo ◽

Kati Donner ◽

...

Keyword(s):

Muscle Weakness ◽

Nemaline Myopathy ◽

Actin Binding ◽

Muscle Fibres ◽

Gene Encoding ◽

Related Disorder ◽

Structural Abnormalities ◽

Muscle Disorder ◽

Myosin Interaction ◽

Nemaline Bodies

NM (nemaline myopathy) is a rare genetic muscle disorder defined on the basis of muscle weakness and the presence of structural abnormalities in the muscle fibres, i.e. nemaline bodies. The related disorder cap myopathy is defined by cap-like structures located peripherally in the muscle fibres. Both disorders may be caused by mutations in the TPM2 gene encoding β-Tm (tropomyosin). Tm controls muscle contraction by inhibiting actin–myosin interaction in a calcium-sensitive manner. In the present study, we have investigated the pathogenetic mechanisms underlying five disease-causing mutations in Tm. We show that four of the mutations cause changes in affinity for actin, which may cause muscle weakness in these patients, whereas two show defective Ca2+ activation of contractility. We have also mapped the amino acids altered by the mutation to regions important for actin binding and note that two of the mutations cause altered protein conformation, which could account for impaired actin affinity.

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