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ZFIN ID: ZDB-PUB-080915-19
Sparc Protein Is Required for Normal Growth of Zebrafish Otoliths
Kang, Y.J., Stevenson, A.K., Yau, P.M., and Kollmar, R.
Date: 2008
Source: Journal of the Association for Research in Otolaryngology : JARO   9(4): 436-451 (Journal)
Registered Authors: Kollmar, Richard
Keywords: inner ear, morphogenesis, biomineral, proteomics, immunofluorescence, antisense oligonucleotides
MeSH Terms:
  • Age Factors
  • Amino Acid Sequence
  • Animals
  • Fluorescent Antibody Technique
  • Gene Expression Regulation, Developmental
  • Mass Spectrometry
  • Minerals/metabolism
  • Molecular Sequence Data
  • Oligonucleotides, Antisense
  • Osteonectin/genetics*
  • Osteonectin/metabolism
  • Otolithic Membrane/embryology
  • Otolithic Membrane/growth & development*
  • Otolithic Membrane/physiology*
  • Proteomics
  • Zebrafish/embryology
  • Zebrafish/growth & development*
  • Zebrafish Proteins/genetics*
  • Zebrafish Proteins/metabolism
PubMed: 18784957 Full text @ J. Assoc. Res. Otolaryngol.
FIGURES
ABSTRACT
Otoliths and the homologous otoconia in the inner ear are essential for balance. Their morphogenesis is less understood than that of other biominerals, such as bone, and only a small number of their constituent proteins have been characterized. As a novel approach to identify unknown otolith proteins, we employed shotgun proteomics to analyze crude extracts from trout and catfish otoliths. We found three proteins that had not been associated previously with otolith or otoconia formation: 'Secreted acidic cysteine rich glycoprotein' (Sparc), an important bone protein that binds collagen and Ca(2+); precerebellin-like protein, which contains a C1q domain and may associate with the collagenous otolin-1 during its assembly into a framework; and neuroserpin, a serine protease inhibitor that may regulate local protease activity during framework assembly. We then used the zebrafish to investigate whether Sparc plays a role in otolith morphogenesis. Immunodetection demonstrated that Sparc is a true constituent of otoliths. Knockdown of Sparc expression in morphant zebrafish resulted in four principal types of defective otoliths: smaller, extra and ectopic, missing and fused, or completely absent. Smaller size was the predominant phenotype and independent of the severity of otic-vesicle defects. These results suggested that Sparc is directly required for normal otolith growth.
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