The Spindle Assembly Checkpoint (SAC) is a signaling pathway responsible for the fidelity of chromosome segregation. Disruption of this process leads to catastrophic cellular consequences, such as aneuploidy and cancer. The primary effector of the SAC is the inhibitory complex known as Mitotic Checkpoint Complex (MCC). MCC is responsible for binding and inhibiting the 1.2 MDa ubiquitin ligase Anaphase-Promoting Complex/Cyclosome (APC). Once all of the sister chromatids achieve proper bipolar orientation, MCC is dismantled. This restores APC activity to trigger the ubiquitin-mediated proteasomal destruction of key mitotic regulators, e.g. Cyclin B and Securin, permitting mitotic exit. The mechanisms of release and disassembly of APC-bound MCC (BUBR1, MAD2, BUB3, and CDC20- an APC coactivator) by a triad of large multiprotein enzymes remain poorly understood.
I aim to dissect this process using an innovative technological approach involving enzyme kinetics, chemical crosslinking, protein engineering, electron microscopy, NMR, crystallography, and cell-based assays. Information generated from the proposed research will have a long- lasting impact on the cell cycle field and may enable the development of novel cancer therapeutics.

Public Health Relevance

Aneuploidy, a hallmark of human cancers, is prevented by a surveillance system known as the Spindle Assembly Checkpoint (SAC). Timely disassembly of the SAC effector, Mitotic Checkpoint Complex (MCC), by several multiprotein complexes is required to ensure accurate chromosome segregation. Comprehensive examination of the structural and enzymatic mechanisms of these molecular machines may enable the design of therapeutics for many cancers.

Agency
National Institute of Health (NIH)
Institute
National Institute of General Medical Sciences (NIGMS)
Type
Unknown (R35)
Project #
5R35GM128855-02
Application #
9747931
Study Section
Special Emphasis Panel (ZGM1)
Program Officer
Gindhart, Joseph G
Project Start
2018-08-01
Project End
2023-07-31
Budget Start
2019-08-01
Budget End
2020-07-31
Support Year
2
Fiscal Year
2019
Total Cost
Indirect Cost
Name
University of North Carolina Chapel Hill
Department
Pharmacology
Type
Schools of Medicine
DUNS #
608195277
City
Chapel Hill
State
NC
Country
United States
Zip Code
27599