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Indications for a novel muscular dystrophy pathway. gamma-filamin, the muscle-specific filamin isoform, interacts with myotilin

Authors

  • P.F. van der Ven
  • S. Wiesner
  • P. Salmikangas
  • D. Auerbach
  • M. Himmel
  • S. Kempa
  • K. Hayess
  • D. Pacholsky
  • A. Taivainen
  • R. Schroeder
  • O. Carpen
  • D.O. Fuerst

Journal

  • Journal of Cell Biology

Citation

  • J Cell Biol 151 (2): 235-248

Abstract

  • gamma-Filamin, also called ABP-L, is a filamin isoform that is specifically expressed in striated muscles, where it is predominantly localized in myofibrillar Z-discs. A minor fraction of the protein shows subsarcolemmal localization. Although gamma-filamin has the same overall structure as the two other known isoforms, it is the only isoform that carries a unique insertion in its immunoglobulin (Ig)-like domain 20. Sequencing of the genomic region encoding this part of the molecule shows that this insert is encoded by an extra exon. Transient transfections of the insert-bearing domain in skeletal muscle cells and cardiomyocytes show that this single domain is sufficient for targeting to developing and mature Z-discs. The yeast two-hybrid method was used to identify possible binding partners for the insert-bearing Ig-like domain 20 of gamma-filamin. The two Ig-like domains of the recently described alpha-actinin-binding Z-disc protein myotilin were found to interact directly with this filamin domain, indicating that the amino-terminal end of gamma-filamin may be indirectly anchored to alpha-actinin in the Z-disc via myotilin. Since defects in the myotilin gene were recently reported to cause a form of autosomal dominant limb-girdle muscular dystrophy, our findings provide a further contribution to the molecular understanding of this disease.


DOI

doi:10.1083/jcb.151.2.235