Skeletal muscle differentiation is a well-orchestrated process regulated by autocrine, paracrine, and endocrine factors via a regulatory network of signal transduction pathways. In recent years the mammalian target of rapamycin (mTOR) has begun to be recognized as a critical regulator of skeletal muscle differentiation, growth and hypertrophy. Work from our laboratory has contributed to the current understanding of mTOR regulation of myoblast differentiation, and has led to the revelation that mTOR regulates multiple stages of myogenesis by assembling distinct pathways, some of which unexpected and yet to be fully delineated. With a combination of biochemical, molecular, cellular and genetic approaches, and utilizing both in vitro and in vivo systems, we aim to fill a sizable gap in the current knowledge of molecular pathways underlying the regulation of skeletal myogenesis by addressing these three major questions: (1) How are the known components of growth-regulating mTOR pathway involved in myogenesis, and what is the mTOR pathway(s) that regulates the initiation of myoblast differentiation in response to amino acids availability signals? (2) What is the mTOR pathway that specifically regulates the second-stage myocyte fusion critical for myotube/myofiber growth and maturation, and which secreted factors regulate this process? (3) What is mTOR's role in muscle regeneration and what are the mechanisms? Our expertise in biochemical characterization of signal transduction mechanisms, our strong preliminary data, and the unique animal models we have created, put us in an ideal position to tackle those questions. Knowledge gained in these studies will contribute to the molecular understanding of skeletal muscle development, repair, regeneration and hypertrophy.

Public Health Relevance

Skeletal muscle differentiation is a well-orchestrated process regulated by autocrine, paracrine, and endocrine factors via multiple signal transduction pathways. Our proposed studies aim to dissect the molecular mechanisms underlying the regulation of skeletal muscle differentiation and regeneration, with a focus on the mammalian target of rapamycin signaling network. Knowledge gained in these studies will contribute to the molecular understanding of skeletal muscle biology, which may have significant impact on health-related issues such as muscular dystrophy, aging or disease-induced muscle atrophy, muscle regeneration, and exercise- induced muscle hypertrophy.

Agency
National Institute of Health (NIH)
Institute
National Institute of Arthritis and Musculoskeletal and Skin Diseases (NIAMS)
Type
Research Project (R01)
Project #
5R01AR048914-09
Application #
8225405
Study Section
Skeletal Muscle and Exercise Physiology Study Section (SMEP)
Program Officer
Boyce, Amanda T
Project Start
2002-07-01
Project End
2014-02-28
Budget Start
2012-03-01
Budget End
2013-02-28
Support Year
9
Fiscal Year
2012
Total Cost
$318,987
Indirect Cost
$109,899
Name
University of Illinois Urbana-Champaign
Department
Anatomy/Cell Biology
Type
Schools of Arts and Sciences
DUNS #
041544081
City
Champaign
State
IL
Country
United States
Zip Code
61820
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Yoon, Mee-Sup; Rosenberger, Christina L; Wu, Cong et al. (2015) Rapid mitogenic regulation of the mTORC1 inhibitor, DEPTOR, by phosphatidic acid. Mol Cell 58:549-56
Waldemer-Streyer, R J; Chen, J (2015) Myocyte-derived Tnfsf14 is a survival factor necessary for myoblast differentiation and skeletal muscle regeneration. Cell Death Dis 6:e2026
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Jain, Ankur; Arauz, Edwin; Aggarwal, Vasudha et al. (2014) Stoichiometry and assembly of mTOR complexes revealed by single-molecule pulldown. Proc Natl Acad Sci U S A 111:17833-8
Zeng, Min; van der Donk, Wilfred A; Chen, Jie (2014) Lanthionine synthetase C-like protein 2 (LanCL2) is a novel regulator of Akt. Mol Biol Cell 25:3954-61
He, Yuan; Li, Dong; Cook, Sara L et al. (2013) Mammalian target of rapamycin and Rictor control neutrophil chemotaxis by regulating Rac/Cdc42 activity and the actin cytoskeleton. Mol Biol Cell 24:3369-80
Ge, Yejing; Waldemer, Rachel J; Nalluri, Ramakrishna et al. (2013) RNAi screen reveals potentially novel roles of cytokines in myoblast differentiation. PLoS One 8:e68068
Yoon, Mee-Sup; Chen, Jie (2013) Distinct amino acid-sensing mTOR pathways regulate skeletal myogenesis. Mol Biol Cell 24:3754-63
Fang, Yimin; Westbrook, Reyhan; Hill, Cristal et al. (2013) Duration of rapamycin treatment has differential effects on metabolism in mice. Cell Metab 17:456-62

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