title: Small heat shock protein HSPB1 regulates growth of embryonic zebrafish craniofacial muscles.
abstract: The small heat shock protein HspB1 (Hsp27) is abundantly expressed in embryonic muscle tissues of a wide variety of vertebrate species. However, the functional significance of this expression pattern is not well established. In the present study, we observed specific, high level expression of HspB1 protein and an HspB1 gene reporter in developing craniofacial muscles of the zebrafish, Danio rerio, and examined the consequences of reducing HspB1 expression to the development and growth of these muscles. Quantitative morphometric analyses revealed a reduction in the cross-sectional area of myofibers in embryos expressing reduced HspB1 levels by as much as 47% compared to controls. In contrast, we detected no differences in the number of myofibrils or associated nuclei, nor the number, size or development of chondrocytes in surrounding tissues. We also did not detect changes to the overall organization of sarcomeres or myofibrils in embryos expressing reduced levels of HspB1. Together our results reveal a critical role for HspB1 in the growth of myofibrils and provide new insight into the mechanism underlying its developmental function.
authors: School of Molecular Biosciences, College of Veterinary Medicine, Washington State University, Pullman, WA, USA.
authors: Ryan C
authors: RC
authors: Middleton
authors: Eric A
authors: EA
authors: Shelden
mesh_terms: D000818:Animals; D030801:Animals, Genetically Modified / Q000196:embryology / Q000235:genetics / Q000378:metabolism; D002452:Cell Count; D002467:Cell Nucleus / Q000235:genetics / Q000378:metabolism; D048429:Cell Size; D019902:Chondrocytes / Q000378:metabolism; D004625:Embryo, Nonmammalian / Q000187:drug effects / Q000378:metabolism; D005152:Facial Muscles / Q000254:growth & development* / Q000378:metabolism; D018507:Gene Expression Regulation, Developmental; D017930:Genes, Reporter; D055551:HSP27 Heat-Shock Proteins / Q000235:genetics / Q000378:metabolism*; D007150:Immunohistochemistry; D009025:Morpholines / Q000008:administration & dosage / Q000494:pharmacology; D024510:Muscle Development; D009210:Myofibrils / Q000235:genetics / Q000378:metabolism; D015027:Zebrafish / Q000196:embryology* / Q000235:genetics / Q000378:metabolism; D029961:Zebrafish Proteins / Q000235:genetics / Q000378:metabolism*
chemical_list: D055551:HSP27 Heat-Shock Proteins; D009025:Morpholines; D029961:Zebrafish Proteins; C503308:hspb1 protein, zebrafish; C037574:morpholine