The mdx mouse is a model of Duchenne muscular dystrophy (DMD), a fatal progres-sive muscle wasting disease caused by dystrophin deficiency, and is used most widely in preclinical studies. Mice with dystrophin deficiency, however, show milder muscle strength phenotypes than humans. In human, the introduction of a sandwich enzyme- linked immunosorbent assay (ELISA) kit revealed a more than 700- fold increase in titin N- terminal fragment levels in the urine of pediatric patients with DMD. Notably, the urinary titin level declines with aging, reflecting progression of muscle wast-ing. In mouse, development of a highly sensitive ELISA kit has been awaited. Here, a sandwich ELISA kit to measure titin N- terminal fragment levels in mouse urine was developed. The developed kit showed good linearity, recovery, and repeatability in measuring recombinant or natural mouse titin N- terminal fragment levels. The titin N- terminal fragment concentration in the urine of mdx mice was more than 500- fold higher than that of normal mice. Urinary titin was further analyzed by extending the collection of urine samples to both young (3– 11 weeks old) and aged (56– 58 weeks old) mdx mice. The concentration in the young group was significantly higher than that in the aged group. It was concluded that muscle protein breakdown is active and persistent in mdx mice even though the muscle phenotype is mild. Our results pro-vide an opportunity to develop DMD treatments that aim to alleviate muscle protein breakdown by monitoring urinary titin levels.

Taku Shirakawa;Ayumu Ikushima;Nobuhiro Maruyama;Yoshinori Nambu;Hiroyuki Awano;Kayo Osawa;Kei Nirasawa;Yoichi Negishi;Hisahide Nishio;Shoji Fukushima;Masafumi Matsuo

Research Center for Locomotion Biology,Kobe Gakuin University,Kobe,Japan;KNC Department of Nucleic Acid Drug Discovery,Faculty of Rehabilitation,Kobe Gakuin University,Kobe,Japan;Department of Pharmaceutics,Faculty of Pharmaceutical Sciences,Kobe Gakuin University,Kobe,Japan;Diagnostic&Research Reagents Division,Immuno-Biological Laboratories Co.,Ltd,Fujioka,Japan;Department of Pediatrics,Kobe University Graduate School of Medicine,Kobe,Japan;Department of Medical Technology, Faculty of Health Sciences,Kobe Tokiwa University,Kobe,Japan;Department of Drug Delivery and Molecular Biopharmaceutics,School of Pharmacy,Tokyo University of Pharmacy and Life Sciences,Tokyo,Japan

动物模型与实验医学（英文）

[1]Taku Shirakawa;Ayumu Ikushima;Nobuhiro Maruyama;Yoshinori Nambu;Hiroyuki Awano;Kayo Osawa;Kei Nirasawa;Yoichi Negishi;Hisahide Nishio;Shoji Fukushima;Masafumi Matsuo-.A sandwich ELISA kit reveals marked elevation of titin N-terminal fragment levels in the urine of mdx mice)[J].动物模型与实验医学（英文）,2022(01):48-55

mdx,wast

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