Journal Article

Functional Substitution by TAT-Utrophin in Dystrophin-Deficient Mice

Baltgalvis, Kristen A., Turner, Amy J., Sonnemann, Kevin J., Ervasti, James M., Heun-Johnson, Hanke, Lowe, Dawn A.

2009

Overview

The loss of dystrophin compromises muscle cell membrane stability and causes Duchenne muscular dystrophy and/or various forms of cardiomyopathy. Increased expression of the dystrophin homolog utrophin by gene delivery or pharmacologic up-regulation has been demonstrated to restore membrane integrity and improve the phenotype in the dystrophin-deficient mdx mouse. However, the lack of a viable therapy in humans predicates the need to explore alternative methods to combat dystrophin deficiency. We investigated whether systemic administration of recombinant full-length utrophin (Utr) or DeltaR4-21 \"micro\" utrophin (muUtr) protein modified with the cell-penetrating TAT protein transduction domain could attenuate the phenotype of mdx mice. Recombinant TAT-Utr and TAT-muUtr proteins were expressed using the baculovirus system and purified using FLAG-affinity chromatography. Age-matched mdx mice received six twice-weekly intraperitoneal injections of either recombinant protein or PBS. Three days after the final injection, mice were analyzed for several phenotypic parameters of dystrophin deficiency. Injected TAT-muUtr transduced all tissues examined, integrated with members of the dystrophin complex, reduced serum levels of creatine kinase (11,290+/-920 U versus 5,950+/-1,120 U; PBS versus TAT), the prevalence of muscle degeneration/regeneration (54%+/-5% versus 37%+/-4% of centrally nucleated fibers; PBS versus TAT), the susceptibility to eccentric contraction-induced force drop (72%+/-5% versus 40%+/-8% drop; PBS versus TAT), and increased specific force production (9.7+/-1.1 N/cm(2) versus 12.8+/-0.9 N/cm(2); PBS versus TAT). These results are, to our knowledge, the first to establish the efficacy and feasibility of TAT-utrophin-based constructs as a novel direct protein-replacement therapy for the treatment of skeletal and cardiac muscle diseases caused by loss of dystrophin.

• Publisher: Public Library of Science,Public Library of Science (PLoS)
• Subject: Animals / Cardiovascular Disorders/Myopathies / Creatine Kinase - blood / Dystrophin - deficiency / Dystrophin - genetics / Gene Products, tat - genetics / Mice / Mice, Inbred mdx / Muscle, Skeletal - metabolism / Muscle, Skeletal - pathology / Muscular Dystrophy, Animal - drug therapy / Muscular Dystrophy, Animal - pathology / Muscular Dystrophy, Duchenne - drug therapy / Muscular Dystrophy, Duchenne - pathology / Neurological Disorders/Neuromuscular Diseases / Recombinant Fusion Proteins - genetics / Recombinant Fusion Proteins - metabolism / Recombinant Fusion Proteins - therapeutic use / Utrophin - genetics / Utrophin - metabolism / Utrophin - therapeutic use