The mammalian target of rapamycin (mTOR) signaling network has emerged as a master regulator of essential processes in cell and developmental biology, including cell growth, proliferation, cellular differentiation, and metabolism. The multiple FDA-approved clinical applications of rapamycin attest to the central importance of mTOR in medicine. Recent evidence has also revealed a key role for mTOR signaling in modulating lifespan in addition to impacting health span. Molecular dissection of the mTOR regulatory network will facilitate development of therapeutics against aging and aging-related diseases, including cardiovascular diseases, metabolic diseases, and cancer. mTOR assembles two biochemically and functionally distinct protein complexes - mTORC1 and mTORC2, which nucleate distinct pathways and yet crosstalk extensively. The current knowledge of mTOR complex assembly is largely derived from conventional biochemical characterizations, which typically require lengthy and strenuous purification procedures that may disrupt native complexes, and offer limited insights into the stoichiometry and heterogeneity of complex formation. We (the Ha laboratory) have recently developed a single-molecule pull-down (SiMPull) method that enables rapid and sensitive analysis of protein complexes at single-complex resolution, directly from whole cell lysates. Here we propose to dissect the assembly of mTORC1 and mTORC2 employing the SiMPul approach. Stoichiometry of each component in the complexes will be determined. Regulation of the complexes by upstream signals, and potential physical crosstalk between the two complexes, will also be examined. Furthermore, we will develop a single-molecule kinase assay with the SiMPull platform, and apply this novel approach to interrogating the activities of various mTOR complexes. The proposed study is expected to decipher the assembly of both mTORC1 and mTORC2 at the single-complex level and reveal structure-function relationships in the mTOR assemblies. Knowledge to be gained from this study will be invaluable in guiding future investigation of the mTOR regulatory network and in facilitating potentially novel design of therapeutic strategies.

Public Health Relevance

The mammalian target of rapamycin (mTOR) signaling network plays a central role in regulating a myriad of cellular and developmental processes that directly impact health span and lifespan. We propose to study mTOR protein complex assembly and activity by employing a novel approach called single-molecule pull-down and developing a single-molecule activity assay. Knowledge to be gained in this study will potentially facilitate development of therapeutics against aging and aging-related diseases.

Agency
National Institute of Health (NIH)
Institute
National Institute on Aging (NIA)
Type
Exploratory/Developmental Grants (R21)
Project #
1R21AG042332-01A1
Application #
8469719
Study Section
Special Emphasis Panel (ZRG1-CB-F (03))
Program Officer
Velazquez, Jose M
Project Start
2013-09-30
Project End
2015-07-31
Budget Start
2013-09-30
Budget End
2014-07-31
Support Year
1
Fiscal Year
2013
Total Cost
$140,000
Indirect Cost
$45,411
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
Hua, Boyang; Han, Kyu Young; Zhou, Ruobo et al. (2014) An improved surface passivation method for single-molecule studies. Nat Methods 11:1233-6