The UCS factor Steif/Unc-45b interacts with the heat shock protein Hsp90a during myofibrillogenesis

Dev Biol. 2007 Aug 1;308(1):133-43. doi: 10.1016/j.ydbio.2007.05.014. Epub 2007 May 18.


Contraction of muscles is mediated by highly organized arrays of myosin motor proteins. We report here the characterization of a mutation of a UCS gene named steif/unc-45b that is required for the formation of ordered myofibrils in both the skeletal and cardiac muscles of zebrafish. We show that Steif/Unc-45b interacts with the chaperone Hsp90a in vitro. The two genes are co-expressed in the skeletal musculature and knockdown of Hsp90a leads to impaired myofibril formation in the same manner as lack of Steif/Unc-45b activity. Transcripts of both genes are up-regulated in steif mutants suggesting co-regulation of the two genes. Our data indicate a requirement of Steif/unc-45b and Hsp90a for the assembly of the contractile apparatus in the vertebrate skeletal musculature.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Amino Acid Sequence
  • Animals
  • Animals, Genetically Modified
  • Base Sequence
  • DNA / genetics
  • Gene Expression Regulation, Developmental
  • HSP90 Heat-Shock Proteins / genetics
  • HSP90 Heat-Shock Proteins / metabolism*
  • Heart / embryology
  • In Vitro Techniques
  • Microscopy, Electron, Transmission
  • Molecular Sequence Data
  • Muscle Development / genetics
  • Muscle Development / physiology*
  • Muscle Proteins / genetics
  • Muscle Proteins / metabolism*
  • Muscle, Skeletal / embryology
  • Muscle, Skeletal / metabolism
  • Muscle, Skeletal / ultrastructure
  • Mutation
  • Myocardium / metabolism
  • Myocardium / ultrastructure
  • Phenotype
  • Zebrafish / embryology*
  • Zebrafish / genetics
  • Zebrafish / metabolism*
  • Zebrafish Proteins / genetics
  • Zebrafish Proteins / metabolism*


  • HSP90 Heat-Shock Proteins
  • Muscle Proteins
  • Unc45b protein, zebrafish
  • Zebrafish Proteins
  • DNA