Document Detail

Founder cells regulate fiber number but not fiber formation during adult myogenesis in Drosophila.
MedLine Citation:
PMID:  18616937     Owner:  NLM     Status:  MEDLINE    
During insect myogenesis, myoblasts are organized into a pre-pattern by specialized organizer cells. In the Drosophila embryo, these cells have been termed founder cells and play important roles in specifying muscle identity and in serving as targets for myoblast fusion. A group of adult muscles, the dorsal longitudinal (flight) muscles, DLMs, is patterned by persistent larval scaffolds; the second set, the dorso-ventral muscles, DVMs is patterned by mono-nucleate founder cells (FCs) that are much larger than the surrounding myoblasts. Both types of organizer cells express Dumbfounded, which is known to regulate fusion during embryonic myogenesis. The role of DVM founder cells as well as the DLM scaffolds was tested in genetic ablation studies using the UAS/Gal4 system of targeted transgene expression. In both cases, removal of organizer cells prior to fusion, causes formation of supernumerary fibers, suggesting that cells in the myoblast pool have the capacity to initiate fiber formation, which is normally inhibited by the organizers. In addition to the large DVM FCs, some (smaller) cells in the myoblast pool also express Dumbfounded. We propose that these cells are responsible for seeding supernumerary fibers, when DVM FCs are eliminated prior to fusion. When these cells are also eliminated, myogenesis fails to occur. In the second set of studies, targeted expression of constitutively active Ras(V12) also resulted in the appearance of supernumerary fibers. In this case, the original DVM FCs are present, suggesting alterations in cell fate. Taken together, these data suggest that DVM myoblasts are able to respond to cues other than the original founder cell, to initiate fusion and fiber formation. Thus, the role of the large DVM founder cells is to generate the correct number of fibers, but they are not required for fiber formation itself. We also present evidence that the DVM FCs may arise from the leg imaginal disc.
Krishan B Atreya; Joyce J Fernandes
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Publication Detail:
Type:  Journal Article; Research Support, N.I.H., Extramural; Research Support, U.S. Gov't, Non-P.H.S.     Date:  2008-06-24
Journal Detail:
Title:  Developmental biology     Volume:  321     ISSN:  1095-564X     ISO Abbreviation:  Dev. Biol.     Publication Date:  2008 Sep 
Date Detail:
Created Date:  2008-08-18     Completed Date:  2008-09-08     Revised Date:  2008-11-21    
Medline Journal Info:
Nlm Unique ID:  0372762     Medline TA:  Dev Biol     Country:  United States    
Other Details:
Languages:  eng     Pagination:  123-40     Citation Subset:  IM    
Department of Zoology, Miami University, Oxford, OH 45056, USA.
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MeSH Terms
Drosophila / growth & development*
Drosophila Proteins / genetics,  metabolism
Membrane Proteins / genetics,  metabolism
Muscle Development
Muscle Proteins / genetics,  metabolism
Muscles / cytology,  embryology
Myoblasts / metabolism
Promoter Regions, Genetic
Grant Support
Reg. No./Substance:
0/Drosophila Proteins; 0/Membrane Proteins; 0/Muscle Proteins; 0/kin of irre protein, Drosophila; 0/reaper protein, Drosophila

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