rst and its paralogue kirre act redundantly during embryonic muscle development in Drosophila.
The polynucleate myotubes of vertebrates and invertebrates form by fusion of myoblasts. We report the involvement of the Drosophila melanogaster Roughest (Rst) protein as a new membrane-spanning component in this process. Rst is strongly expressed in mesodermal tissues during embryogenesis, but rst null mutants display only subtle embryonic phenotypes. Evidence is presented that this is due to functional redundancy between Rst and its paralogue Kirre. Both are highly related single-pass transmembrane proteins with five extracellular immunoglobulin domains and three conserved motifs in the intracellular domain. The expression patterns of kirre and rst overlap during embryonic development in muscle founder cells. Simultaneous deletion of both genes causes an almost complete failure of fusion between muscle founder cells and fusion-competent myoblasts. This defect can be rescued by one copy of either gene. Moreover, Rst, like Kirre is a myoblast attractant.
Strünkelnberg
M
M
Institut für Biologie III, Schänzlestr.1, Albert-Ludwigs-Universität, D-79104 Freiburg im Breisgau, Germany.
Bonengel
B
B
Moda
L M
LM
Hertenstein
A
A
de Couet
H G
HG
Ramos
R G
RG
Fischbach
K F
KF
D000595:Amino Acid Sequence; D000818:Animals; D015816:Cell Adhesion Molecules, Neuronal / Q000235:genetics* / Q000378:metabolism; D029721:Drosophila Proteins; D004331:Drosophila melanogaster / Q000196:embryology* / Q000235:genetics; D004625:Embryo, Nonmammalian; D005136:Eye Proteins; D018507:Gene Expression Regulation, Developmental; D005804:Genes, Lethal; D019476:Insect Proteins / Q000235:genetics* / Q000378:metabolism; D008565:Membrane Proteins; D008969:Molecular Sequence Data; D009124:Muscle Proteins; D018482:Muscle, Skeletal / Q000166:cytology / Q000196:embryology* / Q000473:pathology; D009154:Mutation; D017386:Sequence Homology, Amino Acid
D015816:Cell Adhesion Molecules, Neuronal; D029721:Drosophila Proteins; D005136:Eye Proteins; D019476:Insect Proteins; D008565:Membrane Proteins; D009124:Muscle Proteins; C413082:kirre protein, Drosophila; C085209:rst protein, Drosophila