Identification of Muscle-Specific MicroRNAs in Serum of Muscular Dystrophy Animal Models: Promising Novel Blood-Based Markers for Muscular Dystrophy

Hideya Mizuno,Soichiro Kishi,Yoshitsugu Aoki,Kazuo Hashido,Masayuki Sekiguchi,Naoki Ito,Kazuhiro Yamamoto,Shin'Ichi Takeda,Akinori Nakamura,Sebastien Pfeffer

doi:10.1371/journal.pone.0018388

Hideya Mizuno, Soichiro Kishi + Show 8 more

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https://doi.org/10.1371/journal.pone.0018388

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Abstract

Duchenne muscular dystrophy (DMD) is a lethal X-linked disorder caused by mutations in the dystrophin gene, which encodes a cytoskeletal protein, dystrophin. Creatine kinase (CK) is generally used as a blood-based biomarker for muscular disease including DMD, but it is not always reliable since it is easily affected by stress to the body, such as exercise. Therefore, more reliable biomarkers of muscular dystrophy have long been desired. MicroRNAs (miRNAs) are small, ∼22 nucleotide, noncoding RNAs which play important roles in the regulation of gene expression at the post-transcriptional level. Recently, it has been reported that miRNAs exist in blood. In this study, we hypothesized that the expression levels of specific serum circulating miRNAs may be useful to monitor the pathological progression of muscular diseases, and therefore explored the possibility of these miRNAs as new biomarkers for muscular diseases. To confirm this hypothesis, we quantified the expression levels of miRNAs in serum of the dystrophin-deficient muscular dystrophy mouse model, mdx, and the canine X-linked muscular dystrophy in Japan dog model (CXMDJ), by real-time PCR. We found that the serum levels of several muscle-specific miRNAs (miR-1, miR-133a and miR-206) are increased in both mdx and CXMDJ. Interestingly, unlike CK levels, expression levels of these miRNAs in mdx serum are little influenced by exercise using treadmill. These results suggest that serum miRNAs are useful and reliable biomarkers for muscular dystrophy.

Highlights

Duchenne muscular dystrophy (DMD) is a lethal X-linked disorder caused by mutations in the dystrophin gene, which encodes a cytoskeletal protein, dystrophin[1]
Creatine kinase (CK) is commonly used as a blood-based biomarker for muscular dystrophy to evaluate the level of muscle damage and necrosis, and the efficacy of potential therapies, but it is not always reliable since it is affected by stress to the body, such as exercise[5,6,7]
We demonstrate that the serum levels of several muscle-specific miRNAs are increased in the dystrophin-deficient muscular dystrophy mouse model, mdx, as well as the canine X-linked muscular dystrophy in Japan dog model (CXMDJ) [13,14,15]

Summary

Introduction

Duchenne muscular dystrophy (DMD) is a lethal X-linked disorder caused by mutations in the dystrophin gene, which encodes a cytoskeletal protein, dystrophin[1]. The absence of dystrophin results in progressive degeneration of skeletal and cardiac muscle with fibrotic tissue replacement, fatty infiltration, and subsequent early death by respiratory or heart failure[2,3]. CK is commonly used as a blood-based biomarker for muscular dystrophy to evaluate the level of muscle damage and necrosis, and the efficacy of potential therapies, but it is not always reliable since it is affected by stress to the body, such as exercise[5,6,7]. Other markers for muscular dystrophy, such as myoglobin, aldolase or lactate dehydrogenase, have the same problem. More reliable biomarkers of muscular dystrophy have long been desired

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Conclusion