Myoblast fusion in Drosophila melanogaster is mediated through a fusion‐restricted myogenic‐adhesive structure (FuRMAS)

Abstract

During myogenesis in Drosophila embryos, a prominent adhesive structure is formed between precursor cells and fusion-competent myoblasts (fcms). Here, we show that Duf/Kirre and its interaction partners Rols7 (found in founder myoblasts and growing myotubes) and Sns (found in fcms) are organized in a ring-structure at the contact points of fcms with precursor cells, while cytoskeletal components like F-actin and Titin are centered in this ring in both cell types. The cytoplasmic protein Blow colocalizes with the actin plugs in fcms after cell adhesion. Furthermore, the requirement of additional as yet unidentified components was demonstrated by using mammalian C2C12 myoblasts. In this study, we propose that the fusion-restricted myogenic-adhesive structure (FuRMAS) is pivotal in linking cell adhesion as well as local F-actin assembly and dynamics to downstream events that ultimately lead to plasma membrane fusion. Moreover, we suggest that the FuRMAS may restrict the area of membrane breakdown. Developmental Dynamics 236:404 -415, 2007.

FuRMAS: triggering myoblast fusion in Drosophila

“…The FuRMAS was defined as a ring-like arrangement of cell adhesion molecules (and interacting molecules) with local F-actin accumulation in plugs at the site of myoblast fusion (Kesper et al, 2007; see Fig. 1B1-B3 for the ring-like expression of Duf in fcs).…”

“…1B1-B3 for the ring-like expression of Duf in fcs). F-actin and D-Titin are known to accumulate in fc/growing myotubes and fcms, while Blow is concentrated in fcms (Kesper et al, 2007;Richardson et al, 2007). The Factin plugs at the site of fusion have also been termed actin foci (Kim et al, 2007;Richardson et al, 2007).…”

“…The Factin plugs at the site of fusion have also been termed actin foci (Kim et al, 2007;Richardson et al, 2007). However, before cell adhesion rings (Kesper et al, 2007) and actin plugs/foci (Richardson et al, 2007) can be established, successful cell adhesion must take place. Here, we describe the establishment of the FuRMAS by heterophilic cell adhesion (Figs.…”

“…In Drosophila, heterologous cell adhesion between a founder cell (fc) and a fusion-competent myoblast (fcm) is the precondition for myoblast fusion followed by local F-actin accumulation and branching (Kesper et al, 2007;Kim et al, 2007;Richardson et al, 2007). It has been proposed that a signalling pathway initiated by successful cell adhesion between fcs and fcms relays fusion signals from the cell membrane to the actin cytoskeleton (reviewed by Chen and Olson, 2004).…”

“…It has been proposed that a signalling pathway initiated by successful cell adhesion between fcs and fcms relays fusion signals from the cell membrane to the actin cytoskeleton (reviewed by Chen and Olson, 2004). Recent data show that cell adhesion leads to the assembly of a multiprotein complex at the site of fusion (Kesper et al, 2007;Kim et al, 2007;Richardson et al, 2007), which was named the FuRMAS, a specific Fusion-Restricted Myogenic-Adhesive Structure, that contains F-actin at the sites of cell contact as plugs/foci (Kesper et al, 2007).…”