Muscles in both humans and Drosophila are composed of multinucleate myofibers that are generated by the fusion of myoblasts. However, the events and molecules that regulate myoblast fusion are not well understood. Our long-term goal is to understand myoblast fusion, and in particular, the regulation of the number of fusion events required to create a muscle fiber. The objective of this proposal is to determine the critical cellular and molecular mechanisms controlling myoblast fusion in the model organism, Drosophila melanogaster. The conservation of genes and mechanisms in muscle development between Drosophila and mammals allows us to use the simpler Drosophila system to make relevant discoveries for treatments of human muscular diseases and of muscle wasting due to aging and chemotherapies. Our central hypothesis in this proposal is that specific cytoskeletal rearrangements are critical for myoblast fusion. Guided by our strong preliminary data, this hypothesis will be tested in three specific aims: (1) Identify the critical cytoskeletal rearrangements that underlie myoblast fusion;(2) Determine the requirement of known fusion genes in regulating specific cytoskeletal behaviors underlying myoblast fusion;and (3) Identify the role of new fusion genes in regulating the specific cytoskeletal rearrangements critical for myoblast fusion. Under the first aim, we have developed novel imaging techniques to identify cytoskeletal rearrangements during myoblast fusion in living and fixed embryos. Our preliminary data has pinpointed several such important cytoskeletal rearrangements. Under the second aim, we will test the impact of known fusion genes in relationship to these cytoskeletal rearrangements. Already we can link specific genes'activities to specific cytoskeletal rearrangements. Under the third aim we will investigate the mechanisms underlying the cytoskeletal changes during fusion by examining novel genes that we have identified. Our work is significant because it expected to reveal the cellular and molecular mechanisms underlying cell-cell fusion. The proposed research is relevant to public health because once the molecular players and the cellular targets of their action are identified or understood, therapies designed to regulate myoblast fusion can be developed to promote fusion for the treatment of muscle wasting due to aging or disease.

Agency
National Institute of Health (NIH)
Institute
National Institute of General Medical Sciences (NIGMS)
Type
Research Project (R01)
Project #
5R01GM078318-04
Application #
7904252
Study Section
Skeletal Muscle and Exercise Physiology Study Section (SMEP)
Program Officer
Ainsztein, Alexandra M
Project Start
2007-08-01
Project End
2012-07-31
Budget Start
2010-08-01
Budget End
2012-07-31
Support Year
4
Fiscal Year
2010
Total Cost
$357,390
Indirect Cost
Name
Sloan-Kettering Institute for Cancer Research
Department
Type
DUNS #
064931884
City
New York
State
NY
Country
United States
Zip Code
10065
Deng, Su; Azevedo, Mafalda; Baylies, Mary (2017) Acting on identity: Myoblast fusion and the formation of the syncytial muscle fiber. Semin Cell Dev Biol 72:45-55
Rosen, Jonathan N; Baylies, Mary K (2017) Myofibrils put the squeeze on nuclei. Nat Cell Biol 19:1148-1150
Bothe, Ingo; Baylies, Mary K (2016) Drosophila myogenesis. Curr Biol 26:R786-91
Deng, Su; Bothe, Ingo; Baylies, Mary K (2015) The Formin Diaphanous Regulates Myoblast Fusion through Actin Polymerization and Arp2/3 Regulation. PLoS Genet 11:e1005381
Schulman, Victoria K; Dobi, Krista C; Baylies, Mary K (2015) Morphogenesis of the somatic musculature in Drosophila melanogaster. Wiley Interdiscip Rev Dev Biol 4:313-34
Schulman, Victoria K; Folker, Eric S; Rosen, Jonathan N et al. (2014) Syd/JIP3 and JNK signaling are required for myonuclear positioning and muscle function. PLoS Genet 10:e1004880
Folker, Eric S; Schulman, Victoria K; Baylies, Mary K (2014) Translocating myonuclei have distinct leading and lagging edges that require kinesin and dynein. Development 141:355-66
Bothe, Ingo; Deng, Su; Baylies, Mary (2014) PI(4,5)P2 regulates myoblast fusion through Arp2/3 regulator localization at the fusion site. Development 141:2289-301
Aguilar, Pablo S; Baylies, Mary K; Fleissner, Andre et al. (2013) Genetic basis of cell-cell fusion mechanisms. Trends Genet 29:427-37
Schulman, Victoria K; Folker, Eric S; Baylies, Mary K (2013) A method for reversible drug delivery to internal tissues of Drosophila embryos. Fly (Austin) 7:193-203

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