The cell cycle control is a fundamental regulatory process that ensures the faithful duplication and passage of genetic information during cell division. To prevent the irreversible incorporation of genetic lesions into the genome, the transitions between the G1/S and G2/M phases of cell cycle are highly regulated as part of the checkpoint control in respond to environmental cues. Aberrant cell cycle control abolishes coordination between different phases of the cell cycle and is a hallmark of neoplastic transformation. The broad, long-term objective of this proposal is to understand the mechanism of cell cycle control in cell growth and differentiation, and the consequences of its alteration during tumorigenesis. This proposal focuses on the mechanism of the G1/S cell cycle transition in mammalian cells. In particular, we describe the approaches to investigate the mechanism by which the levels of the mammalian G1 cyclins and CDK inhibitors are controlled through the selective ubiquitin-dependent degradation during the G1/S transition. The accumulation of the G1 cyclins are the rate limiting step during the G1/S transition and the CDK inhibitors usually serve as the G1/S checkpoint control proteins in response to negative growth signals. Over-expression of the G1 cyclins and the loss of CDK inhibitors are often associated with human cancer. We have previously isolated a novel p19SKP1 and p45SKP2 cell cycle complex based on its highly elevated level in many neoplastic transformed cells. We have identified additional components of this complex. Our preliminary data indicate that this complex is involved in the control of the G1/S transition by regulating the levels of the G1 cell cycle regulators through the ubiquitin-dependent proteolysis. To further investigate this important cell cycle control mechanism, we propose the following specific aims: (1) To determine and characterize the components that are involved in the control of the G/S transition through the p19SKP1 and p45SKP2-mediated ubiquitin-dependent proteolysis. (2) To identify the critical targets of this regulation during the G1/S transition. (3) To determine the cell cycle regulatory factors that control this process. (4) To establish in vitro assays to characterize the ubiquitin conjugation reaction and its regulatory mechanism. Our investigation should provide new insights into the mechanism of the mammalian G1/S transition and help to assess how the alteration of these cell cycle regulatory processes may contribute to tumorigenesis. These studies will also provide a molecular basis for designing novel strategies for the diagnostic and therapeutic treatment of human cancer.

Agency
National Institute of Health (NIH)
Institute
National Cancer Institute (NCI)
Type
Research Project (R01)
Project #
5R01CA072878-03
Application #
6150049
Study Section
Cellular Biology and Physiology Subcommittee 1 (CBY)
Program Officer
Spalholz, Barbara A
Project Start
1998-04-01
Project End
2003-01-31
Budget Start
2000-02-01
Budget End
2001-01-31
Support Year
3
Fiscal Year
2000
Total Cost
$280,728
Indirect Cost
Name
Yale University
Department
Genetics
Type
Schools of Medicine
DUNS #
082359691
City
New Haven
State
CT
Country
United States
Zip Code
06520
Higa, Leigh Ann; Yang, Xiaoming; Zheng, Jianyu et al. (2006) Involvement of CUL4 ubiquitin E3 ligases in regulating CDK inhibitors Dacapo/p27Kip1 and cyclin E degradation. Cell Cycle 5:71-7
Higa, Leigh Ann; Wu, Min; Ye, Tao et al. (2006) CUL4-DDB1 ubiquitin ligase interacts with multiple WD40-repeat proteins and regulates histone methylation. Nat Cell Biol 8:1277-83
Higa, Leigh Ann; Banks, Damon; Wu, Min et al. (2006) L2DTL/CDT2 interacts with the CUL4/DDB1 complex and PCNA and regulates CDT1 proteolysis in response to DNA damage. Cell Cycle 5:1675-80
Banks, Damon; Wu, Min; Higa, Leigh Ann et al. (2006) L2DTL/CDT2 and PCNA interact with p53 and regulate p53 polyubiquitination and protein stability through MDM2 and CUL4A/DDB1 complexes. Cell Cycle 5:1719-29
Shim, Eun-Hee; Johnson, Linda; Noh, Hye-Lim et al. (2003) Expression of the F-box protein SKP2 induces hyperplasia, dysplasia, and low-grade carcinoma in the mouse prostate. Cancer Res 63:1583-8
Higa, Leigh Ann A; Mihaylov, Ivailo S; Banks, Damon P et al. (2003) Radiation-mediated proteolysis of CDT1 by CUL4-ROC1 and CSN complexes constitutes a new checkpoint. Nat Cell Biol 5:1008-15
Zheng, Jianyu; Yang, Xiaoming; Harrell, Jennifer M et al. (2002) CAND1 binds to unneddylated CUL1 and regulates the formation of SCF ubiquitin E3 ligase complex. Mol Cell 10:1519-26
Mihaylov, Ivailo S; Kondo, Takeshi; Jones, Lynn et al. (2002) Control of DNA replication and chromosome ploidy by geminin and cyclin A. Mol Cell Biol 22:1868-80
Yang, Xiaoming; Menon, Suchithra; Lykke-Andersen, Karin et al. (2002) The COP9 signalosome inhibits p27(kip1) degradation and impedes G1-S phase progression via deneddylation of SCF Cul1. Curr Biol 12:667-72
Yokouchi, M; Kondo, T; Sanjay, A et al. (2001) Src-catalyzed phosphorylation of c-Cbl leads to the interdependent ubiquitination of both proteins. J Biol Chem 276:35185-93

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