NEDDylation has been shown to participate in the DNA damage pathway, but the substrates of neural precursor cell expressed developmentally downregulated 8 （NEDD8） and the roles of NEDDylation involved in the DNA dam...NEDDylation has been shown to participate in the DNA damage pathway, but the substrates of neural precursor cell expressed developmentally downregulated 8 （NEDD8） and the roles of NEDDylation involved in the DNA damage response （DDR） are largely unknown. Translesion synthesis （TLS） is a damage-tolerance mechanism, in which RAD181RAD6-mediated monoubiq- uitinated proliferating cell nuclear antigen （PCNA） pro- motes recruitment of polymerase q （polq） to bypass lesions. Here we identify PCNA as a substrate of NEDD8, and show that E3 ligase RAD18-catalyzed PCNA NEDDylation antagonizes its ubiquitination. In addition, NEDP1 acts as the deNEDDylase of PCNA, and NEDP1 deletion enhances PCNA NEDDylation but reduces its ubiquitination. In response to H202 stimulation, NEDP1 disassociates from PCNA and RAD18-dependent PCNA NEDDylation increases markedly after its ubiquitination. impairment of NEDDylation by Ubc12 knockout enhances PCNA ubiquitination and promotes PCNA-polη interaction, while up-regulation of NEDDylation by NEDD8 overexpression or NEDP1 deletion reduces the excessive accumulation of ubiquitinated PCNA, thus inhibits PCNA-polη interaction and blocks polη foci formation. Moreover, Ubc12 knockout decreases cell sensitivity to H2O2-induced oxidative stress, but NEDP1 deletion aggravates this sensitivity. Collectively, our study elucidates the important role of NEDDylation in the DDR as a modulator of PCNA monoubiquitination and polη recruitment.展开更多
Based on a specially adapted questionnaire,research was carried out to explore how resources in modern distance learning were being applied in rural elementary and middle schools in Western China,in order to enhance t...Based on a specially adapted questionnaire,research was carried out to explore how resources in modern distance learning were being applied in rural elementary and middle schools in Western China,in order to enhance the usefulness of the allocated resources.One particular distance learning project was used as the subject of the study,and teachers at 22 rural elementary and middle schools in 3 prefecture-level cities in Gansu Province,Western China,acted as the sample group.Analysis of the teachers’questionnaire responses showed that,(1)there is a comparatively high number of modern distance learning resources in use in rural elementary and middle schools in Western China,and they are being effectively used in the classroom to assist in everyday teaching;(2)teachers of rural elementary and middle schools in Western China have the ability to make use of these modern resources,and can obtain them by way of multi-channel inquiry;(3)modern distance learning resources are already becoming important components of everyday teaching resources in Western China;and(4)teachers are generally able to apply these resources well,despite some problems remaining.In the case of problems in application,most teachers are able to find adequate solutions.展开更多
基金We sincerely thank Profs. Jun Huang, Wensheng Wei, and Caixia Guo for providing the plasmids used in this study. We thank Millennium Pharmaceuticals for providing the MLN4924 used in this study. This work was supported by the National Natural Science Foundation of China （Grant Nos. 31470754, 81730080 and 31670786）, the National Key Research and Development Program of China （2016YFC1302401）.
文摘NEDDylation has been shown to participate in the DNA damage pathway, but the substrates of neural precursor cell expressed developmentally downregulated 8 （NEDD8） and the roles of NEDDylation involved in the DNA damage response （DDR） are largely unknown. Translesion synthesis （TLS） is a damage-tolerance mechanism, in which RAD181RAD6-mediated monoubiq- uitinated proliferating cell nuclear antigen （PCNA） pro- motes recruitment of polymerase q （polq） to bypass lesions. Here we identify PCNA as a substrate of NEDD8, and show that E3 ligase RAD18-catalyzed PCNA NEDDylation antagonizes its ubiquitination. In addition, NEDP1 acts as the deNEDDylase of PCNA, and NEDP1 deletion enhances PCNA NEDDylation but reduces its ubiquitination. In response to H202 stimulation, NEDP1 disassociates from PCNA and RAD18-dependent PCNA NEDDylation increases markedly after its ubiquitination. impairment of NEDDylation by Ubc12 knockout enhances PCNA ubiquitination and promotes PCNA-polη interaction, while up-regulation of NEDDylation by NEDD8 overexpression or NEDP1 deletion reduces the excessive accumulation of ubiquitinated PCNA, thus inhibits PCNA-polη interaction and blocks polη foci formation. Moreover, Ubc12 knockout decreases cell sensitivity to H2O2-induced oxidative stress, but NEDP1 deletion aggravates this sensitivity. Collectively, our study elucidates the important role of NEDDylation in the DDR as a modulator of PCNA monoubiquitination and polη recruitment.
文摘Based on a specially adapted questionnaire,research was carried out to explore how resources in modern distance learning were being applied in rural elementary and middle schools in Western China,in order to enhance the usefulness of the allocated resources.One particular distance learning project was used as the subject of the study,and teachers at 22 rural elementary and middle schools in 3 prefecture-level cities in Gansu Province,Western China,acted as the sample group.Analysis of the teachers’questionnaire responses showed that,(1)there is a comparatively high number of modern distance learning resources in use in rural elementary and middle schools in Western China,and they are being effectively used in the classroom to assist in everyday teaching;(2)teachers of rural elementary and middle schools in Western China have the ability to make use of these modern resources,and can obtain them by way of multi-channel inquiry;(3)modern distance learning resources are already becoming important components of everyday teaching resources in Western China;and(4)teachers are generally able to apply these resources well,despite some problems remaining.In the case of problems in application,most teachers are able to find adequate solutions.
