The cell division cycle is orchestrated by the timed synthesis and subsequent ubiquitin-mediated proteolysis of key regulatory proteins. Two ubiquitin ligase complexes that are known to regulate the cell cycle are the Anaphase Promoting Complex (APC) and Skp1-Cul1-F-box (SCF) complex. However, there are numerous cell cycle regulators for which the mechanism of turnover remains unknown, and a large number of ubiquitin ligases whose targets have not been identified. To better understand how ubiquitin ligases control the cell cycle, we developed a method that utilizes a library of strains expressing GFP-fusion proteins and highthroughput microscopy to identify ubiquitin ligase targets in yeast, and are using this approach to identify the ubiquitin ligases that target 73 unstable cell cycle regulators for destruction. In the experiments proposed here, we will determine the mechanism of turnover of these cell cycle proteins by specific E3s, and examine the importance of these turnover events for nonnal cell cycle progression. The SCF(Gn'l) ubiquitin ligase is known to target both cell cycle and metabolic regulators for destruction. We previously identified the transcription factor Tye7 as a SCF(Grrl) target. Tye7 regulates transcription of metabolic genes and is itself transcriptionally regulated throughout the cell cycle. We will detennine Tye7 is targeted for degradation and analyze the consequence of blocking SCF-mediated turnover. Finally, we will investigate how the cell cycle and metabolic factors influence SCF ligase activity. SCF ligases recognize targets through one of many modular adaptor subunits called F-box proteins. It is unknown how many F-box proteins complex with the SCF at any one time, and whether these complexes change throughout the cell cycle. We will analyze SCF complex composition in different cell cycle and growth states to address these questions.

Public Health Relevance

l /lost cells in the body tightly control growth and division so that they only duplicate when appropriate. When these controls break down and cells divide at incorrect times, this leads to the development of cancer. The cell division cycle is regulated by the timed synthesis and destruction of regulatory molecules. Understanding how timed destruction of these molecules occurs will Increase our understanding of processes disrupted in cancer cells.

Agency
National Institute of Health (NIH)
Institute
National Institute of General Medical Sciences (NIGMS)
Type
Research Transition Award (R00)
Project #
5R00GM085013-05
Application #
8258793
Study Section
Special Emphasis Panel (NSS)
Program Officer
Hamlet, Michelle R
Project Start
2008-08-01
Project End
2014-04-30
Budget Start
2012-05-01
Budget End
2014-04-30
Support Year
5
Fiscal Year
2012
Total Cost
$246,510
Indirect Cost
$96,656
Name
University of Massachusetts Medical School Worcester
Department
Genetics
Type
Schools of Medicine
DUNS #
603847393
City
Worcester
State
MA
Country
United States
Zip Code
01655
Edenberg, Ellen R; Vashisht, Ajay; Benanti, Jennifer A et al. (2014) Rad53 downregulates mitotic gene transcription by inhibiting the transcriptional activator Ndd1. Mol Cell Biol 34:725-38
Landry, Benjamin D; Mapa, Claudine E; Arsenault, Heather E et al. (2014) Regulation of a transcription factor network by Cdk1 coordinates late cell cycle gene expression. EMBO J 33:1044-60
Benanti, Jennifer A (2012) Coordination of cell growth and division by the ubiquitin-proteasome system. Semin Cell Dev Biol 23:492-8