The partitioning-defective 3 （Par3）, a key component in the conserved Par3/Par6/aPKC complex, plays fundamental roles in cell polarity. Herein we report the identification of Ku70 and Ku80 as novel Par3-interacting proteins through an in vitro binding assay followed by liquid chromatography-tandem mass spectrometry. Ku70/Ku80 proteins are two key regulatory subunits of the DNA-dependent protein kinase （DNA-PK）, which plays an essential role in repairing double-strand DNA breaks （DSBs）. We determined that the nuclear association of Par3 with Ku70/Ku80 was enhanced by γ-irradiation （IR）, a potent DSB inducer. Furthermore, DNA-PKcs, the catalytic subunit of DNA-PK, interacted with the Par3/Ku70/Ku80 complex in response to IR. Par3 over-expression or knockdown was capable of up- or downregulating DNA-PK activity, respectively. Moreover, the Par3 knockdown cells were found to be defective in random plasmid integration, defective in DSB repair following IR, and radiosensitive, phenotypes similar to that of Ku70 knockdown cells. These findings identify Par3 as a novel component of the DNA-PK complex and implicate an unexpected link of cell polarity to DSB repair.
Longhou FangYiGuo WangDan DuGuang YangTim Tak KwokSiu Kai KongBenjamin ChenDavid J ChenZhengjun Chen
The author affiliations were mixed up in the previous published version. The third fund number of National NaturalScience Foundation of China in the Acknowledgments was wrong, it should be "30270335". The Shanghai MunicipalCouncil for Science and Technology (No.06DZ22032) was missed in the Acknowledgments. There are some labelingand production errors in Figure 2A, Figure 3B and 3C, Figure 5C, Figure 6B and 6E, Figure 7B and 7D. In Figure 2A,left panel "A431" should be "Par3". In Figure 3B and 3C, "anti-Par3CT" should be "anti-Par3LCT", "GST-Par3CT"should be "GST-Par3LCT". In Figure 5C, the second arrow indicating "Lamin B" should be "[3-tubulin". In Figure 6Bright panel, the molecular weight for ?-actin should be "43" instead of"200". In Figure 6E, "Par3" should be "Par3i". Themolecular weight for the DNA-PKcs panel should be the same as the p-DNA-PKcs. In Figure 7B, the time point "240"in the left panel should be "120"; in the right panel of Figure 7B, the title for the y axis should be "DNA released (%)".In Figure 7D, the title for the y axis should be "Survival (%)", and the scale for the y axis should be "100, 10 and 1". These corrections do not affect the conclusions of the study. We apologize for any inconvenience this may havecaused.
Longhou FangtYiGuo WangDan DutGuang YangTim Tak KwokSiu Kai KongBenjamin ChenDavid J ChenZhengjun Chen
Dear Editor, Human embryonic stem （ES） cells possess the potential to differentiate into all the cell types of the human body and provide potential applications in regenerative medicine . However, the concerns of immune rejection hamper transplantation therapies using human ES cells. To avoid the complications of immune rejection, diverse methods, such as somatic nuclear transfer （also called therapeutic cloning） and fusion of somatic ceils with human ES ceils , have been attempted to produce patient-specific pluripotent stem cells. Most of these approaches have resulted in little success. The generation of human iPS cells （induced
Jing Liao Zhao Wu Ying Wang Lu Cheng Chun Cui Yuan Gao Taotao Chen Lingjun Rao Siye Chen Nannan Jia Huiming Dai Shunmei Xin Jiuhong Kang Gang Pei Lei Xiao
