Cell membrane integrity in myotonic dystrophy type 1: implications for therapy

• Published in: PloS one 2015-03, Vol.10 (3), p.e0121556
• Main Authors: González-Barriga, Anchel, Kranzen, Julia, Croes, Huib J E, Bijl, Suzanne, van den Broek, Walther J A A, van Kessel, Ingeborg D G, van Engelen, Baziel G M, van Deutekom, Judith C T, Wieringa, Bé, Mulders, Susan A M, Wansink, Derick G
• Format: Article
• Language: English
• Subjects: Aberration; Adult; Aged; Aged, 80 and over; Animal models; Animal tissues; Animals; Antisense oligonucleotides; Biology; Biopsy; Brain; Calcium; Calcium (intracellular); Calcium - metabolism; Cell Membrane - metabolism; Cell Membrane Permeability; Cell membranes; Cell surface; Child; Creatine; Creatine kinase; Disease; DMPK protein; Drug delivery; Drug delivery systems; Drugs; Dystrophin; Dystrophin - genetics; Dystrophin - metabolism; Dystrophy; Enzymes; Evans Blue - pharmacokinetics; Female; Fitness equipment; Humans; Integrity; Kinases; Life sciences; Male; Membrane proteins; Membrane structure; Membranes; Mice; Mice, Inbred C57BL; Middle Aged; Muscles; Muscular dystrophy; Myotonic dystrophy; Myotonic Dystrophy - drug therapy; Myotonic Dystrophy - metabolism; Oligonucleotides; Pathogenesis; Patients; Permeability; Polyglutamine; Protein binding; Protein structure; Proteins; Ribonucleic acid; RNA; RNA-protein interactions; Rodents; Skeletal muscle; Splicing; Therapy; Toxic diseases; Trinucleotide repeats; Utrophin
• ISSN: 1932-6203; 1932-6203
• DOI: 10.1371/journal.pone.0121556

Myotonic Dystrophy type 1 (DM1) is a multisystemic disease caused by toxic RNA from a DMPK gene carrying an expanded (CTG•CAG)n repeat. Promising strategies for treatment of DM1 patients are currently being tested. These include antisense oligonucleotides and drugs for elimination of expanded RNA or prevention of aberrant binding to RNP proteins. A significant hurdle for preclinical development along these lines is efficient systemic delivery of compounds across endothelial and target cell membranes. It has been reported that DM1 patients show elevated levels of markers of muscle damage or loss of sarcolemmal integrity in their serum and that splicing of dystrophin, an essential protein for muscle membrane structure, is abnormal. Therefore, we studied cell membrane integrity in DM1 mouse models commonly used for preclinical testing. We found that membranes in skeletal muscle, heart and brain were impermeable to Evans Blue Dye. Creatine kinase levels in serum were similar to those in wild type mice and expression of dystrophin protein was unaffected. Also in patient muscle biopsies cell surface expression of dystrophin was normal and calcium-positive fibers, indicating elevated intracellular calcium levels, were only rarely seen. Combined, our findings indicate that cells in DM1 tissues do not display compromised membrane integrity. Hence, the cell membrane is a barrier that must be overcome in future work towards effective drug delivery in DM1 therapy.