The long-term objective of this application is to characterize what appears to be a new cellular mechanism for regulating the activity of protein phosphatase 2A (PP2A), an enzyme which plays a critical role in modulating cell growth regulatory pathways by dephosphorylating key proteins in these pathways. Specifically, we propose that a protein called HSF2 regulates PP2A activity by binding to the PR65/A subunit of PP2A and preventing its association with the catalytic subunit by directly competing with catalytic subunit for its binding site in PR65. The biological relevance of HSF2's ability to block interaction between PR65 and catalytic subunit is demonstrated by results showing that mutations in PR65 that prevent binding of catalytic subunit are associated with human lung and colon cancers. HSF2 is also known to be a transcription factor which regulates expression of heat shock protein (hsp) genes, and thus we hypothesize that HSF2 regulation of PP2A could serve as a mechanism for cross-talk between control of hsp expression and cell growth regulatory pathways. To elucidate the function of HSF2 as a novel regulator of PP2A we propose to 1) identify the sequences in HSF2 and PR65 important for this interaction, 2) characterize cellular mechanisms which regulate the HSF2:PR65 interaction, 3) determine the function of HSF2 in regulating cellular PP2A activity, and 4) identify other potential members of this new class of PP2A regulatory protein using yeast two-hybrid interaction screens (we have already identified one new candidate using this meth6d, a growth regulatory protein called mel-18). These studies will advance knowledge by elucidating a new mechanism of PP2A regulation as well as a new mechanism for cross-talk between two important signaling pathways in cells, hsp regulation and control of cell growth/differentiation. This knowledge could aid understanding of both normal cell growth regulation as well as aberrant proliferation control in cancer cells.

Agency
National Institute of Health (NIH)
Institute
National Institute of General Medical Sciences (NIGMS)
Type
Research Project (R01)
Project #
5R01GM061053-04
Application #
6700760
Study Section
Physiological Chemistry Study Section (PC)
Program Officer
Jones, Warren
Project Start
2001-02-01
Project End
2006-01-31
Budget Start
2004-02-01
Budget End
2006-01-31
Support Year
4
Fiscal Year
2004
Total Cost
$210,322
Indirect Cost
Name
University of Kentucky
Department
Biochemistry
Type
Schools of Medicine
DUNS #
939017877
City
Lexington
State
KY
Country
United States
Zip Code
40506
Gandhapudi, Siva K; Murapa, Patience; Threlkeld, Zachary D et al. (2013) Heat shock transcription factor 1 is activated as a consequence of lymphocyte activation and regulates a major proteostasis network in T cells critical for cell division during stress. J Immunol 191:4068-79
Sarge, Kevin D; Park-Sarge, Ok-Kyong (2011) SUMO and its role in human diseases. Int Rev Cell Mol Biol 288:167-83
Xing, Hongyan; Hong, Yiling; Sarge, Kevin D (2010) PEST sequences mediate heat shock factor 2 turnover by interacting with the Cul3 subunit of the Cul3-RING ubiquitin ligase. Cell Stress Chaperones 15:301-8
Sarge, Kevin D; Park-Sarge, Ok-Kyong (2009) Sumoylation and human disease pathogenesis. Trends Biochem Sci 34:200-5
Sarge, Kevin D; Xing, Hongyan; Park-Sarge, Ok-Kyong (2009) Chromosome-wide analysis of protein binding and modifications. Methods Mol Biol 590:223-33
Wilkerson, Donald C; Sarge, Kevin D (2009) RNA polymerase II interacts with the Hspa1b promoter in mouse epididymal spermatozoa. Reproduction 137:923-9
Sarge, Kevin D; Park-Sarge, Ok-Kyong (2009) Mitotic bookmarking of formerly active genes: keeping epigenetic memories from fading. Cell Cycle 8:818-23
Sarge, Kevin D; Park-Sarge, Ok-Kyong (2009) Detection of proteins sumoylated in vivo and in vitro. Methods Mol Biol 590:265-77
Zhang, Jie; Goodson, Michael L; Hong, Yiling et al. (2008) MEL-18 interacts with HSF2 and the SUMO E2 UBC9 to inhibit HSF2 sumoylation. J Biol Chem 283:7464-9
Wilkerson, Donald C; Murphy, Lynea A; Sarge, Kevin D (2008) Interaction of HSF1 and HSF2 with the Hspa1b promoter in mouse epididymal spermatozoa. Biol Reprod 79:283-8

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