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.

Amphioxus muscle transcriptomes reveal vertebrate-like myoblast fusion genes and a highly conserved role of insulin signalling in the metabolism of muscle

“…Sns ( Sticks and stones ) [ 11 ] and Hbs ( Hibris ) [ 4 , 28 , 110 ] in FCMs bind to Duf ( Dumfounded a.k.a. Kirre ( Kin of Irregular-chiasm-C )) [ 105 ] and Rst ( Roughest a.k.a.…”

Selective endocytosis controls slit diaphragm maintenance and dynamics

“…For immunofluorescence, nephrocytes were dissected, fixed for 20 minutes in PBS containing 4% paraformaldehyde, and stained according to the standard procedure. The following primary antibodies were used: rabbit anti-sns 42 (1:200, gift from S. Abmayr) and guinea pig anti-Kirre 43 (1:200, gift from S. Abmayr). Other antibodies used were rabbit anti-Rab5 (ab18211, abcam), mouse anti-Rab7 (Rab7, DSHB), mouse anti-Myc (9E10; DSHB), mouse anti-c-Myc (sc-40; Santa Cruz Biotechnology), and rabbit anti-RAB11 (#5589S; Cell Signaling Technology).…”

Drosophila melanogaster: A Model System to Study Distinct Genetic Programs in Myoblast Fusion

“…Dumbfounded (Duf/Kirre) and its homolog Roughest (Rst) are expressed in founder cells where they serve redundant functions [26]. Hibris (Hbs), Sticks and Stones (Sns), and Roughest (Rst) are found in fusion-competent myoblasts [27,28]. Duf, Sns, and Rst are expressed in a ring-like structure at cell-cell contact points [29].…”