title: Heat-shock protein 90alpha1 is required for organized myofibril assembly in skeletal muscles of zebrafish embryos.
abstract: Heat-shock protein 90alpha (Hsp90alpha) is a member of the molecular chaperone family involved in protein folding and assembly. The role of Hsp90alpha in the developmental process, however, remains unclear. Here we report that zebrafish contains two Hsp90alpha genes, Hsp90alpha1, and Hsp90alpha2. Hsp90alpha1 is specifically expressed in developing somites and skeletal muscles of zebrafish embryos. We have demonstrated that Hsp90alpha1 is essential for myofibril organization in skeletal muscles of zebrafish embryos. Knockdown of Hsp90alpha1 resulted in paralyzed zebrafish embryos with poorly organized myofibrils in skeletal muscles. In contrast, knockdown of Hsp90alpha2 had no effect on muscle contraction and myofibril organization. The filament defects could be rescued in a cell autonomous manner by an ectopic expression of Hsp90alpha1. Biochemical analyses revealed that knockdown of Hsp90alpha1 resulted in significant myosin degradation and up-regulation of unc-45b gene expression. These results indicate that Hsp90alpha1 plays an important role in muscle development, likely through facilitating myosin folding and assembly into organized myofibril filaments.
authors.affiliation: Center of Marine Biotechnology, University of Maryland Biotechnology Institute, 701 East Pratt Street, Baltimore, MD 21202, USA. dus@umbi.umd.edu
authors.forename: Shao Jun
authors.initials: SJ
authors.lastname: Du
authors.forename: Huiqing
authors.initials: H
authors.lastname: Li
authors.forename: Yuehong
authors.initials: Y
authors.lastname: Bian
authors.forename: Yongwang
authors.initials: Y
authors.lastname: Zhong
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D018507:Gene Expression Regulation, Developmental; D018841:HSP90 Heat-Shock Proteins / Q000737:chemistry*; D018832:Molecular Chaperones / Q000378:metabolism; D008969:Molecular Sequence Data; D009124:Muscle Proteins / Q000737:chemistry; D018482:Muscle, Skeletal / Q000196:embryology*; D009210:Myofibrils / Q000378:metabolism*; D009218:Myosins / Q000737:chemistry; D016376:Oligonucleotides, Antisense / Q000737:chemistry; D017386:Sequence Homology, Amino Acid; D012689:Sequence Homology, Nucleic Acid; D015027:Zebrafish; D029961:Zebrafish Proteins / Q000737:chemistry
chemical_list: D018841:HSP90 Heat-Shock Proteins; D018832:Molecular Chaperones; D009124:Muscle Proteins; D016376:Oligonucleotides, Antisense; C472790:Unc45b protein, zebrafish; D029961:Zebrafish Proteins; D009218:Myosins