The MARVEL domain protein, Singles Bar, is required for progression past the pre-fusion complex stage of myoblast fusion

Estrada, Beatriz and Maeland, Anne D. and Gisselbrecht, Stephen S. and Bloor, James W. and Brown, Nicholas H. and Michelson, Alan M. (2007) The MARVEL domain protein, Singles Bar, is required for progression past the pre-fusion complex stage of myoblast fusion. Developmental Biology, 307 (2). pp. 328-339. ISSN 0012-1606 . (The full text of this publication is not available from this repository)

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Official URL
http://dx.doi.org/10.1016/j.ydbio.2007.04.045

Abstract

Multinucleated myotubes develop by the sequential fusion of individual myoblasts. Using a convergence of genomic and classical genetic approaches, we have discovered a novel gene, singles bar (sing), that is essential for myoblast fusion. sing encodes a small multipass transmembrane protein containing a MARVEL domain, which is found in vertebrate proteins involved in processes such as tight junction formation and vesicle trafficking where-as in myoblast fusion-membrane apposition occurs. sing is expressed in both founder cells and fusion competent myoblasts, preceding and during myoblast fusion. Examination of embryos injected with double-stranded sing RNA or embryos homozygous for ethane methyl sulfonate-induced sing alleles revealed an identical phenotype: replacement of multinucleated myofibers by groups of single, myosin-expressing myoblasts at a stage when formation of the mature muscle pattern is complete in wild-type embryos. Unfused sing mutant myoblasts form clusters, suggesting that early recognition and adhesion of these cells are unimpaired. To further investigate this phenotype, we undertook electron microscopic ultrastructural studies of fusing myoblasts in both sing and wild-type embryos. These experiments revealed that more sing mutant myoblasts than wild-type contain pre-fusion complexes, which are characterized by electron-dense vesicles paired on either side of the fusing plasma membranes. In contrast, embryos mutant for another muscle fusion gene, blown fuse (blow), have a normal number of such complexes. Together, these results lead to the hypothesis that sing acts at a step distinct from that of blow, and that sing is required on both founder cell and fusion-competent myoblast membranes to allow progression past the pre-fusion complex stage of myoblast fusion, possibly by mediating fusion of the electron-dense vesicles to the plasma membrane.

Item Type: Article
Uncontrolled keywords: cell-cell fusion; myoblast fusion; mesoderm; myogenesis; muscle; development; Drosophila; MARVEL domain
Subjects: Q Science > QH Natural history > QH426 Genetics
Divisions: Faculties > Science Technology and Medical Studies > School of Biosciences
Depositing User: James W Bloor
Date Deposited: 07 Jul 2008 14:36
Last Modified: 12 May 2014 15:54
Resource URI: http://kar.kent.ac.uk/id/eprint/9896 (The current URI for this page, for reference purposes)
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