Tsu-Fang Wu1, Ya-Li Yao2, I-Lu Lai3, Tsung-Han Lee4, D Alan Underhill5, Wen-Ming Yang6. 1. Department of Life Sciences, National Chung Hsing University, Taichung, Taiwan, R.O.C. Department of Applied Cosmetology, Hung Kuang University, Taichung, Taiwan, R.O.C. 2. Department of Biotechnology, Asia University, Taichung, Taiwan, R.O.C. 3. Institute of Molecular Biology, National Chung Hsing University, Taichung, Taiwan, R.O.C. 4. Department of Life Sciences, National Chung Hsing University, Taichung, Taiwan, R.O.C. 5. Experimental Oncology, Department of Oncology, University of Alberta, Cross Cancer Institute, Edmonton, AB, Canada. 6. Institute of Molecular Biology, National Chung Hsing University, Taichung, Taiwan, R.O.C. yangwm@nchu.edu.tw.
Abstract
BACKGROUND: Proper re-establishment of heterochromatin after each round of DNA replication is critical to the preservation of cell identity. Paired box 3 (PAX3), a transcription factor important in embryonic development, was found to mediate the formation of pericentromeric heterochromatin. However, how PAX3 recognizes the heterochromatic environment and re-establishes it after DNA replication remains unclear. MATERIALS AND METHODS: Cell-cycle synchronization, fluorescence microscopic analyses, and co-immunoprecipitation were used to analyze the heterochromatic localization of PAX3 in HEK 293 cells and NIH 3T3 cells. RESULTS: We found that PAX3 binds pericentromeric heterochromatin during middle-to-late S phase. Loading of PAX3 onto pericentromeric heterochromatin requires poly(ADP-ribose) polymerase 1 (PARP1). Furthermore, loss of PAX3 or PARP1 delays cell-cycle progression through the S phase. CONCLUSION: Our results reveal how PAX3 recognizes and maintains pericentromeric heterochromatin at the S phase of the cell cycle. Copyright
BACKGROUND: Proper re-establishment of heterochromatin after each round of DNA replication is critical to the preservation of cell identity. Paired box 3 (PAX3), a transcription factor important in embryonic development, was found to mediate the formation of pericentromeric heterochromatin. However, how PAX3 recognizes the heterochromatic environment and re-establishes it after DNA replication remains unclear. MATERIALS AND METHODS: Cell-cycle synchronization, fluorescence microscopic analyses, and co-immunoprecipitation were used to analyze the heterochromatic localization of PAX3 in HEK 293 cells and NIH 3T3 cells. RESULTS: We found that PAX3 binds pericentromeric heterochromatin during middle-to-late S phase. Loading of PAX3 onto pericentromeric heterochromatin requires poly(ADP-ribose) polymerase 1 (PARP1). Furthermore, loss of PAX3 or PARP1 delays cell-cycle progression through the S phase. CONCLUSION: Our results reveal how PAX3 recognizes and maintains pericentromeric heterochromatin at the S phase of the cell cycle. Copyright