研究室: 臺大生化館N203
電 話:

(02)33664066 ; (02)23620261 ext. 5574

傳 真: (02)23635038
地 址:

(10617)
台北市大安區羅斯福路四段1號
國立臺灣大學生化科學研究所

電子信箱: peterhchi@ntu.edu.tw

2007 Ph.D., Department of Molecular Biophysics and Biochemistry, Yale University

2010 Postdoctoral Associate, Yale University
2008-2010 The Rockefeller University

 

Our Interests

Our laboratory is interested in deciphering the functional and mechanistic role of homologous recombination in biology.

  The Biology of Homologous Recombination

Homologous recombination (HR) governs genomic transactions. It represents a major chromosome repair tool that helps to eliminate deleterious lesions such as DNA double strand breaks (DSBs), mediate the restart of stalled or collapsed DNA replication forks, ensure proper meiotic chromosome segregation, as well as to maintain the length of telomeres in some circumstances (Fig. 1). As such, HR is indispensable for the maintenance of genome integrity. Studies in the past have provided compelling evidence for a tumor suppression role of HR. For instance, cell lines from familial breast cancer patients that harbor mutations in BRCA2 exhibit hypersensitivity to DNA damaging agents and a pronounced deficiency in HR. Aside from its genome maintenance and tumor suppression functions, HR also serves more specialized roles in various organisms, such as mating type switching in the budding yeast and V(D)J recombination in the immune system. In summary HR play an essential role in biology and dysregulation of HR causes severe disease such as cancer.

Figure 1. Biological Roles of Homologous Recombination (HR)

 

Homologous Recombination Pathway 

HR is often induced via the formation of DSBs, which leads to the nucleolytic processing of DSB ends to generate 3' single-stranded DNA (ssDNA) tails. Herein, the 3' single-stranded tail associates with recombinases to form a nucleoprotein filament, which is then activated to invade a homologous duplex DNA molecule to form a displacement loop or D-loop. The 3' invading strand is extended by DNA synthesis, followed by the pairing of the non-invading 3' single-stranded tail with the homologous ssDNA strand in the enlarging D-loop (second end capture). The now paired second 3' end is also extended by DNA synthesis and subsequent ligations generate a double Holliday Junction (dHJ) intermediate. Resolution of the dHJ intermediate can result in crossover or non-crossover recombinant products (Fig. 2). In summary, the HR pathway is constituted by a sequence of events that involve (1) DSBs formation; (2) end resection to create 3' overhang ssDNA; (3) assembly of recombinase onto ssDNA; (4) D-loop mediated DNA synthesis; and (5) formation & resolution of dHJ intermediate.

Figure 2. Homologous Recombination (HR) Pathway

The DNA double strand break (DSB) is resected to generate 3' ssDNA overhangs. Invasion of a homologous DNA molecule by one of these 3' ssDNA tails gives rise to a D-loop intermediate. After DNA synthesis, the second DNA end is captured to form an intermediate with two Holliday Junctions (HJ)s. Resolution of the Holliday Junctions yields either non-crossover or crossover products.

 

 

Our Missions

We are fascinated with sophisticated HR process and our desire is to focus on several related projects directed at understanding the action mechanisms of HR in accomplishing their biological mission. We hope the molecular insights garnered from our studies could potentially provide the basis for devising strategies to prevent and treat various cancers such as breast cancer.

  葉欣怡
蘇綸勤
張皓衍
李致瑩
王函悠
許家嘉
陳奕成
高誌遠
江宜蓁
林柏廷
柯旻佑
蔡孟真
余貞瑩
李佳怡
謝竣丞

2015 Chang, H.Y., Liao, C.Y., Su, G.C., Lin, S.W., Wang, H.W., Chi, P. (2015) Functional Relationship of ATP Hydrolysis, Presynaptic Filament Stability, and Homologous DNA Pairing Activity of the Human Meiotic Recombinase DMC1. J Biol Chem., 290(32):19863-73.
2014 Zhao, W., Saro, D., Hammel, M., Kwon, Y., Xu, Y., Rambo, R.P., Williams, G.J., Chi, P., Lu, L., Pezza, R.J., Camerini-Otero, R.D., Tainer, J.A., Wang, H.W., Sung, P. (2014) Mechanistic insights into the role of Hop2-Mnd1 in meiotic homologous DNA pairing. Nucleic Acids Res., 42(2):906-17.
2014 Su, G.C., Chung, C.I., Liao, C.Y., Lin, S.W., Tsai, C.T., Huang, T., Li, H.W., Chi, P. (2014) Enhancement of ADP release from the RAD51 presynaptic filament by the SWI5-SFR1 complex. Nucleic Acids Res., 42(1):349-58.
2013 Wilson, M.A., Kwon, Y., Xu, Y., Chung, W.H., Chi, P., Niu, H., Mayle, R., Chen, X., Malkova, A., Sung, P., Ira, G. (2013) Pif1 helicase and Polδ promote recombination-coupled DNA synthesis via bubble migration. Nature, 502(7471):393-6.
2013 Busygina, V., Gaines, W.A., Xu, Y., Kwon, Y., Williams, G.J., Lin, S.W., Chang, H.Y., Chi, P., Wang, H.W., and Sung, P. (2013) Functional attributes of the Saccharomyces cerevisiae meiotic recombinase Dmc1. DNA Repair (Amst), 12(9):707-12.
2012 Tsai, S.P., Su, G.C., Lin, S.W., Chung, C.I., Xue, X., Dunlop, M.H., Akamatsu, Y., Jasin, M., Sung, P., and Chi, P. (2012) Rad51 presynaptic filament stabilization function of the mouse Swi5-Sfr1 heterodimeric complex. Nucleic Acids Res., 40 (14):6558-69.
2012 Chen, C.H., Chu, P.C., Lee, L., Lien, H.W., Lin, T.L., Fan, C.C., Chi, P., Huang, C.J., and Chang, M.S. (2012) Disruption of murine mp29/Syf2/Ntc31 gene results in embryonic lethality with aberrant checkpoint response. PLoS One, e33538.
2011 Chi, P., Kwon, Y., Visnapuu, M.L., Lam, I., Santa Maria, S.R., Zheng, X., Epshtein, A., Greene, E.C., Sung, P., and Klein, H.L. (2011) Analyses of the yeast Rad51 recombinase A265V mutant reveal different in vivo roles of Swi2-like factors. Nucleic Acids Res., 1-12.
2010 Niu, H., Chung, W.H., Zhu, Z., Kwon, Y., Zhao, W., Chi, P., Prakash, P., Seong, C., Liu, D., Lu, L., Ira, G., and Sung, P. (2010) Mechanism of the ATP-dependent DNA end-resection machinery from Saccharomyces cerevisiae. Nature, 467(7311):108-11.
2009 Robertson, R.B., Moses, D.N., Kwon, Y., Chan, P., Chi, P., Klein, H., Sung, P., and Greene, E.C. (2009) Structural transitions within human Rad51 nucleoprotein filaments. PNAS, 106(31):12688-93.
2009 Chi, P., Kwon, Y., Moses, D.N., Seong, C., Sehorn, M.G., Singh, A.K., Tsubouchi, H., Greene, E.C., Klein, H.L., and Sung, P. (2009) Functional interactions of meiotic recombination factors Rdh54 and Dmc1. DNA Repair (Amst), 8(2):279-84.
2009 Robertson, R.B., Moses, D.N., Kwon, Y., Chan, P., Chi, P., Klein, H., Sung, P., and Greene, E.C., (2009) Visualizing the disassembly of S.cerevisiae Rad51 nucleoprotein filaments. J. Mol. Biol., 388(4):703-20.
2008 Seong, C., Sehorn, M.G., Plate, I., Shi, I., Song, B., Chi, P., Mortensen, U., Sung, P., and Krejci, L. (2008) Molecular anatomy of the recombination mediator function of Saccharomyces cerevisiae Rad52. J. Biol. Chem., 283(18):12166-74.
2008 Kwon, Y., Seong, C., Chi, P., Greene, E.C., Klein, H., and Sung, P. (2008) ATP-dependent chromatin remodeling by the Saccharomyces cerevisiae homologous recombination factor Rdh54/Tid1. J. Biol. Chem., 283(16):10445-52.
2007 Hu, Y., Raynard, S., Sehorn, M.G., Lu, X., Bussen, W., Zheng, L., Stark, J.M., Barnes, E.L., Chi, P., Janscak, P., Jasin, M., Vogel, H., Sung, P., and Luo, G. (2007) RECQL5/Recql5 helicase regulates homologous recombination and suppresses tumor formation via disruption of Rad51 presynaptic filaments. Genes & Develop., 21(23):3078-84.
2007 Chi, P., San Filippo, J., Sehorn, M.G., Petukhova, G.V., and Sung, P. (2007) Bipartite stimulatory action of the Hop2-Mnd1 complex on the Rad51 recombinase. Genes & Develop., 21(14):1747-57.
2007 Kwon,Y., Chi, P., Roh, D. H., Klein, H., and Sung, P. (2007) Synergistic action of the Saccharomyces cerevisiae homologous recombination factors Rad54 and Rad51 in chromatin remodeling. DNA Repair (Amst), 6(10):1496-506.
2007 Prasad, T.K., Robertson, R.B., Visnapuu, M.L., Chi, P., Sung, P., and Greene, E.C. (2007) A DNA-translocating Snf2 molecular motor: Saccharomyces cerevisiae Rdh54 displays processive translocation and extrudes DNA loops. J. Mol. Biol., 369(4):940-53.
2006 Chi, P., Kwon, Y., Seong, C., Epshtein, A., Lam, I., Sung, P., and Klein, H. L. (2006) Yeast recombination factor Rdh54 functionally interacts with the Rad51 recombinase and catalyzes Rad51 removal from DNA. J. Biol. Chem., 281(36):26268-79.
2006 Chi, P., Van Komen, S., Sehorn, M.G., Sigurdsson, S., and Sung, P. (2006) Roles of ATP binding and ATP hydrolysis in human Rad51 recombinase function. DNA Repair (Amst), 5(3): 381-91.
2006 San Filippo, J., Chi, P., Sehorn, M.G., Etchin, J., Krejci, L., and Sung, P. (2006) Recombination mediator and Rad51 targeting activities of a human BRCA2 polypeptide. J. Biol. Chem., 281 (17):11649-57.
2004 Raschle, M., Van Komen, S., Chi, P., Ellenberger, T., and Sung, P. (2004) Multiple interactions with the Rad51 recombinase govern the homologous recombination function of Rad54. J. Biol.Chem., 279(50):51973-80.
1998 Chi, P., Doong, S.L., Lin-Shiau, S.Y., Boone, C. W., Kelloff, G. J., and Lin, J.K. (1998) Oltipraz, a novel inhibitor of hepatitis B virus transcription through elevation of p53 protein. Carcinogenesis,19(12):2133-2138. (Note: my name was Wei-Jie Chi in the publication)