title: Drosophila SNS, a member of the immunoglobulin superfamily that is essential for myoblast fusion.
abstract: The Drosophila sticks-and-stones (sns) locus was identified on the basis of its mutant phenotype, the complete absence of body wall muscles and corresponding presence of unfused myoblasts. The genetic location of the mutation responsible for this apparent defect in myoblast fusion was determined by recombination and deficiency mapping, and the corresponding wild-type gene was isolated in a molecular walk. Identification of the SNS coding sequence revealed a putative member of the immunoglobulin superfamily (IgSF) of cell adhesion molecules. As anticipated from this homology, SNS is enriched at the membrane and clusters at discrete sites, coincident with the occurrence of myoblast fusion. Both the sns transcript and the encoded protein are expressed in precursors of the somatic and visceral musculature of the embryo. Within the presumptive somatic musculature, SNS expression is restricted to the putative fusion-competent cells and is not detected in unfused founder cells. Thus, SNS represents the first known marker for this subgroup of myoblasts, and provides an opportunity to identify pathways specifying this cell type as well as transcriptional regulators of fusion-specific genes. To these ends, we demonstrate that the presence of SNS-expressing cells is absolutely dependent on Notch, and that expression of SNS does not require the myogenic regulatory protein MEF2.
authors.affiliation: Department of Biochemistry and Molecular Biology, Penn State University, University Park, PA 16802 USA.
authors.forename: B A
authors.initials: BA
authors.lastname: Bour
authors.forename: M
authors.initials: M
authors.lastname: Chakravarti
authors.forename: J M
authors.initials: JM
authors.lastname: West
authors.forename: S M
authors.initials: SM
authors.lastname: Abmayr
mesh_terms: D000483:Alleles; D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D002448:Cell Adhesion / Q000235:genetics; D002462:Cell Membrane / Q000378:metabolism; D002874:Chromosome Mapping; D004268:DNA-Binding Proteins / Q000378:metabolism; D004330:Drosophila / Q000196:embryology / Q000235:genetics* / Q000276:immunology*; D029721:Drosophila Proteins; D004625:Embryo, Nonmammalian / Q000378:metabolism; D017930:Genes, Reporter / Q000235:genetics; D007136:Immunoglobulins / Q000096:biosynthesis / Q000737:chemistry / Q000235:genetics* / Q000502:physiology*; D064326:MEF2 Transcription Factors; D008565:Membrane Proteins / Q000235:genetics / Q000378:metabolism*; D008957:Models, Genetic; D008969:Molecular Sequence Data; D018485:Muscle Fibers, Skeletal / Q000737:chemistry*; D009132:Muscles / Q000196:embryology*; D009154:Mutation; D018006:Myogenic Regulatory Factors; D010641:Phenotype; D051880:Receptors, Notch; D017386:Sequence Homology, Amino Acid; D013997:Time Factors; D014157:Transcription Factors / Q000378:metabolism
chemical_list: D004268:DNA-Binding Proteins; D029721:Drosophila Proteins; D007136:Immunoglobulins; D064326:MEF2 Transcription Factors; C499409:Mef2 protein, Drosophila; D008565:Membrane Proteins; D018006:Myogenic Regulatory Factors; C497759:N protein, Drosophila; D051880:Receptors, Notch; C410904:SNS protein, Drosophila; D014157:Transcription Factors