Transgenic mice expressing the myotilin T57I mutation unite the pathology associated with LGMD1A and MFM.

Journal Article

Myotilin is a muscle-specific Z-disc protein with putative roles in myofibril assembly and structural upkeep of the sarcomere. Several myotilin point mutations have been described in patients with limb-girdle muscular dystrophy type 1A (LGMD1A), myofibrillar myopathy (MFM), spheroid body myopathy (SBM), three similar adult-onset, progressive and autosomal dominant muscular dystrophies. To further investigate myotilin's role in the pathogenesis of these muscle diseases, we have characterized three independent lines of transgenic mice expressing mutant (T57I) myotilin under the control of the human skeletal actin promoter. Similar to LGMD1A and MFM patients, these mice develop progressive myofibrillar pathology that includes Z-disc streaming, excess myofibrillar vacuolization and plaque-like myofibrillar aggregation. These aggregates become progressively larger and more numerous with age. We show that the mutant myotilin protein properly localizes to the Z-disc and also heavily populates the aggregates, along with several other Z-disc associated proteins. Whole muscle physiological analysis reveals that the extensor digitorum longus muscle of transgenic mice exhibits significantly reduced maximum specific isometric force compared with littermate controls. Intriguingly, the soleus and diaphragm muscles are spared of any abnormal myopathology and show no reductions in maximum specific force. These data provide evidence that myotilin mutations promote aggregate-dependent contractile dysfunction. In sum, we have established a promising patho-physiological mouse model that unifies the phenotypes of LGMD1A, MFM and SBM.

Full Text

Duke Authors

Cited Authors

  • Garvey, SM; Miller, SE; Claflin, DR; Faulkner, JA; Hauser, MA

Published Date

  • August 1, 2006

Published In

Volume / Issue

  • 15 / 15

Start / End Page

  • 2348 - 2362

PubMed ID

  • 16801328

International Standard Serial Number (ISSN)

  • 0964-6906

Digital Object Identifier (DOI)

  • 10.1093/hmg/ddl160

Language

  • eng

Conference Location

  • England