Hay-Oak Park

Focus

Regulation of Cell Growth and Oriented Cell Division; Oxidative Stress Response

Research interests

Our lab is interested in understanding the molecular mechanisms by which GTPases control various cellular processes in response to intra- and extra-cellular signals. One project focuses on the function of GTPases that control cell growth and division using the budding yeast Saccharomyces cerevisiae as a model system. Yeast cells undergo oriented cell division by choosing a specific site for growth depending on their cell type. The choice of a growth site determines the axis of cell polarity and the cell division plane. Proper choice of cell division plane is critical for growth of many other cells including epithelial tissues. It is thought that escape from the normal growth controls of the epithelial cells is a critical step in the initiation of cancer. Thus, elucidation of the GTPase regulatory circuitry that controls cell growth and division has important health-related implications.

Yeast cells exhibit two distinct budding patterns that reflect the genetic programming of cell polarization. It is believed that these different patterns occur in response to the cell-type-specific cortical markers. A GTPase module comprised of the Ras-family GTPase Rsr1/Bud1, its GDP/GTP exchange factor Bud5, and its GTPase activating protein Bud2, is necessary for these specific growth patterns. The Rho-family GTPase Cdc42 and its associated proteins then establish an axis of polarized growth by triggering an asymmetric organization of the actin cytoskeleton and secretory apparatus at the selected site for growth. We combine techniques in genetics, biochemistry, and cell biology, to study the structure-function relationships of GTPases and their regulators.

Another project focuses on the role of Rho GTPases in oxidant signaling and the oxidative stress response. Oxidative stress occurs when cellular defense mechanisms are unable to cope with increased reactive oxygen species (ROS) in the cell. ROS have been associated with a number of age-related diseases including cancer, heart disease, and neurodegenerative diseases. We aim to establish the signaling pathways that regulate cellular redox balance by using functional genomic and biochemical methods.

Park Lab Members:

Research Scientist: Pil Jung Kang 

Graduate  Students: Komudi Singh, Mid eum Lee

Undergraduate Students: Bryanta Spencer, Dominik Berdysz

Research Staff: Jonathon Konz

 

 

 

 

Publications

• Singh, K., P. J. Kang, and H.-O. Park* (2008) The Rho5 GTPase is necessary for oxidant-induced cell death in budding yeast. Proc. Natl. Acad. Sci. USA 105: 1522-1527
• Park, H.-O.* and E. Bi (2007) Central roles of small GTPases in the development of cell polarity in yeast and beyond. Microbiology & Molecular Biology Reviews, 71: 48-96
• Kang, P. J., B. Lee, and H.-O. Park * (2004) Specific residues of the GDP/GTP exchange factor Bud5p are involved in the cell-type-specific budding pattern in yeast. J. Biol. Chem., 279: 27980-27985 . (Epub 2004 May 10).
• Kang, P. J., E. Angerman , K. Nakashima, J. R. Pringle, and H.-O. Park* (2004) Interactions among Rax1p, Rax2p, Bud8p, and Bud9p in Marking Cortical Sites for Bipolar Bud-site Selection in Yeast. Mol. Biol. Cell, 15: 5145-5157 (Epub. 2004 Sept 08).
• Kozminski, K. G.@, L. Beven@, E. Angerman, A. Tong, C. Boone, & H.-O. Park* (2003) Interaction between a Ras-like and a Rho-like GTPase couples the selection of a growth site to the development of cell polarity. Mol. Biol. Cell 14: 4958-4970. -- received the "MBC Paper of the Year" Award.
• Park, H.-O.*, P. J. Kang, and A. W. Rachfal (2002) Localization of the Bud1/Rsr1 GTPase involved in selection of a proper growth site in yeast. J. Biol. Chem. 277: 26721-26724. (Epub 2002 Jun 10).
• Kang, P. J., A. Sanson, B. Lee, & H.-O. Park* (2001) A GDP/GTP exchange factor involved in linking a spatial landmark to cell polarity. Science 292:1376-1378. (Science Express, 19 April, 2001) - reviewed in Curr. Biol. (2001) 11:R610-R612