Mind bomb 2, a founder myoblast-specific protein, regulates myoblast fusion and muscle stability
| Autor: | Marta Carrasco-Rando, Mar Ruiz-Gómez |
|---|---|
| Rok vydání: | 2008 |
| Předmět: |
Sarcomeres
Embryo Nonmammalian Sarcomere Cell Fusion Myoblasts Myoblast fusion Animals Drosophila Proteins Myocyte Muscle Skeletal Molecular Biology In Situ Hybridization Genetics Microscopy Confocal Cell fusion biology Myogenesis Gene Expression Regulation Developmental Immunohistochemistry Ubiquitin ligase Myotube differentiation Cell biology Microscopy Electron biology.protein Drosophila Carrier Proteins Myofibril Developmental Biology |
| Zdroj: | Development. 135:849-857 |
| ISSN: | 1477-9129 0950-1991 |
| Popis: | A fundamental step during Drosophila myogenesis is the specification of founder myoblasts (FMs). Founders possess the information required for the acquisition of muscle identity and for the execution of the myogenic programme, whereas fusion-competent myoblasts (FCMs) acquire this information after fusing to founders. Very little is known about genes that implement the execution of the myogenic programme. Here we characterise Mind bomb 2 (Mib2), a protein with putative E3 ubiquitin ligase activity that is exclusive of FMs and necessary for at least two distinct steps of the founder/myotube differentiation programme. Thus, in mib2 mutants, the early process of myoblast fusion is compromised, as FMs undergo a reduced number of rounds of fusion with FCMs. At later stages, with the onset of muscle contraction, many muscles degenerate, display aberrant sarcomeric structure and detach from tendons. The fusion process requires intact E3-RING-finger domains of Mib2 (the putative catalytic sites), probably to eliminate the FCM-specific activator Lmd from nascent myotubes. However, these sites appear dispensable for muscle integrity. This, and the subcellular accumulation of Mib2 in Z and M bands of sarcomeres, plus its physical interaction with nonmuscle myosin (a Z-band-localised protein necessary for the formation of myofibrils), suggest a structural role for Mib2 in maintaining sarcomeric stability. We suggest that Mib2 acts sequentially in myoblast fusion and sarcomeric stability by two separable processes involving distinct functions of Mib2. |
| Databáze: | OpenAIRE |
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