lindsay-mousemodelsof-2018.pdf (1.54 MB)
Mouse models of two missense mutations in actin-binding domain 1 of dystrophin associated with duchenne or becker muscular dystrophy
journal contribution
posted on 2018-02-01, 00:00 authored by J L McCourt, D M Talsness, Angus Lindsay, R W Arpke, P D Chatterton, D M Nelson, C M Chamberlain, J T Olthoff, J J Belanto, P M McCourt, M Kyba, D A Lowe, J M ErvastiMissense mutations in the dystrophin protein can cause Duchenne muscular dystrophy (DMD) or Becker muscular dystrophy (BMD) through an undefined pathomechanism. In vitro studies suggest that missense mutations in the N-terminal actinbinding domain (ABD1) cause protein instability, and cultured myoblast studies reveal decreased expression levels that can be restored to wild-type with proteasome inhibitors. To further elucidate the pathophysiology of missense dystrophin in vivo, we generated two transgenic mdx mouse lines expressing L54R or L172H mutant dystrophin, which correspond to missense mutations identified in human patients with DMD or BMD, respectively. Our biochemical, histologic and physiologic analysis of the L54R and L172H mice show decreased levels of dystrophin which are proportional to the phenotypic severity. Proteasome inhibitors were ineffective in both the L54R and L172H mice, yet mice homozygous for the L172H transgene were able to express even higher levels of dystrophin which caused further improvements in muscle histology and physiology. Given that missense dystrophin is likely being degraded by the proteasome but whole body proteasome inhibition was not possible, we screened for ubiquitin-conjugating enzymes involved in targeting dystrophin to the proteasome. A myoblast cell line expressing L54R mutant dystrophin was screened with an siRNA library targeting E1, E2 and E3 ligases which identified Amn1, FBXO33, Zfand5 and Trim75. Our study establishes new mouse models of dystrophinopathy and identifies candidate E3 ligases that may specifically regulate dystrophin protein turnover in vivo
History
Journal
Human Molecular GeneticsVolume
27Issue
3Pagination
451 - 462Publisher
Oxford University PressLocation
Oxford, Eng.Publisher DOI
ISSN
0964-6906eISSN
1460-2083Language
engPublication classification
C1 Refereed article in a scholarly journalUsage metrics
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