DOI
https://doi.org/10.25772/YT55-NY74
Defense Date
2016
Document Type
Thesis
Degree Name
Master of Science
Department
Human Genetics
First Advisor
Larisa Litovchick
Abstract
The DREAM complex assembles during G0/G1 when RB-like protein p130 recruits E2F4, DP1, and a core complex of five MuvB proteins to repress genes involved in cell cycle progression. In S-phase, the MuvB core dissociates from p130 and binds to BMYB transcription factor. Binding of the MuvB core to p130 requires phosphorylation of its subunit LIN52 at S28 residue by DYRK1A protein kinase. However, little is known about how the MuvB core interacts with p130 to form the DREAM complex, and how these interactions are manipulated throughout the cell cycle. In collaboration with Dr. Seth Rubin, we characterized the structural basis for DREAM assembly, and found that the LxSxExL sequence in LIN52 directly interacts with the LxCxE binding cleft within the pocket domain of p130. Furthermore, immunoprecipitation and proliferation assays revealed that mutating the LIN52 LxSxExL sequence to mimic the canonical LxCxE motif found in viral oncoproteins reduces cellular proliferation and stabilizes the DREAM complex in the presence of viral proteins. We addressed how the DREAM complex is disassembled upon cell cycle entry and found that CDK phosphorylation of p130 inactivates the DREAM complex by displacing p130 from the MuvB core. Under certain conditions, we found that BMYB and p130 simultaneously bind the MuvB core, while overexpression of BMYB disrupts DREAM assembly. Together, our study provides insight into the structural mechanisms of DREAM assembly and function, which can help identify novel approaches to halt tumor cell proliferation or dormancy.
Rights
© The Author
Is Part Of
VCU University Archives
Is Part Of
VCU Theses and Dissertations
Date of Submission
4-29-2016