The role of hHR23A function in mammalian cell cycle progression

• Main Authors: Xiao-Tong Tan, 陳筱彤
• Other Authors: Show-Mei Chuang
• Format: Others
• Language: zh-TW
• Published: 2012
• Online Access: http://ndltd.ncl.edu.tw/handle/11363471089685662878

碩士 === 國立中興大學 === 生物醫學研究所 === 100 === Rad23 is an evolutionarily conserved protein from yeast to human. Human cells express two isoforms of Rad23, named hHR23A and hHR23B. Rad23 plays a critical role in nuclear excision repair (NER) and ubiquitin-proteasome system (UPS). However, the signaling regulation of Rad23 function is still unclear. In the previous experiments showed that ubiquitin chain binding ability of hHR23 might be used for degradation of cell cycle regulator protein, which consequently affect the cell cycle progression. hHR23 proteins has been shown a key role to regulate cell cycle progression in yeast but seldom investigated in mammalian cells. Based on it, the goal of our study is to distinguish the different role of hHR23 homologs in mammalian cell cycle progression. Therefore, we further knocked down hHR23 by siRNA and shRNA and found that knockdown of hHR23 didnt affect cell cycle progression. Interestingly, depletion of hHR23 expression led to significantly enhance cisplatin induced cell cycle delay. Depended on these results, we suggest that hHR23A is important for cell cycle progression but hHR23B plays a different role in it. Moreover, from cell synchronize assay, we showed that knockdown of hHR23A alone delay cell cycle progression and cell division. Based on these results, we screened cell cycle regulator proteins and tested which protein was effected when depletion of hHR23A. In collectively, we found that Checkpoint kinase 1 (Chk1) was being upregulated with or without DNA damage agent in knockdown hHR23A cell lines. Moreover, immunoprecipitated analysis showed that Chk1 and hHR23A interaction in nucleus and hHR23A responsible for Chk1 degradation. In sum, the molecular mechanism of hHR23A and Chk1 regulates cell cycle progression by signaling will be further investigated.