Engineering of a new type of plant base editor for simultaneous adenine transition and transversion within the editing window will greatly expand the scope and potential of base editing in directed evolution and crop ...Engineering of a new type of plant base editor for simultaneous adenine transition and transversion within the editing window will greatly expand the scope and potential of base editing in directed evolution and crop improvement.Here,we isolated a rice endogenous hypoxanthine excision protein,N-methylpurine DNA glycosylase(OsMPG),and engineered two plant A-to-K(K=G or T)base editors,rAKBE01 and rAKBE02,for simultaneous adenine transition and transversion base editing in rice by fusing OsMPG or its mutant mOsMPG to a plant adenine transition base editor,ABE8e.We further coupled either OsMPG or mOsMPG with a transactivation factor VP64 to generate rAKBE03 and rAKBE04,respectively.Testing these four rAKBEs,at five endogenous loci in rice protoplasts,indicated that rAKBE03 and rAKBE04 enabled higher levels of A-to-G base transitions when compared to ABE8e and ABE8e-VP64.Furthermore,whereas rAKBE01 only enabled A-to-C/T editing at one endogenous locus,in comparison with rAKBE02 and rAKBE03,rAKBE04 could significantly improve the A-to-C/T base transversion efficiencies by up to 6.57-and 1.75-fold in the rice protoplasts,respectively.Moreover,although no stable lines with A-to-C transversion were induced by rAKBE01 and rAKBE04,rAKBE04 could enable simultaneous A-to-G and A-to-T transition and transversion base editing,at all the five target loci,with the efficiencies of A-to-G transition and A-to-T transversion editing ranging from 70.97 to 92.31%and 1.67 to 4.84%in rice stable lines,respectively.Together,these rAKBEs enable different portfolios of editing products and,thus,now expands the potential of base editing in diverse application scenario for crop improvement.展开更多
Temozolomide(TMZ)is an anticancer agent used to treat glioblastoma,typically following radiation therapy and/or surgical resection.However,despite its effectiveness,at least 50%of patients do not respond to TMZ,which ...Temozolomide(TMZ)is an anticancer agent used to treat glioblastoma,typically following radiation therapy and/or surgical resection.However,despite its effectiveness,at least 50%of patients do not respond to TMZ,which is associated with repair and/or tolerance of TMZ-induced DNA lesions.Studies have demonstrated that alkyladenine DNA glycosylase(AAG),an enzyme that triggers the base excision repair(BER)pathway by excising TMZ-induced N3-methyladenine(3meA)and N7-methylguanine lesions,is overexpressed in glioblastoma tissues compared to normal tissues.Therefore,it is essential to develop a rapid and efficient screening method for AAG inhibitors to overcome TMZ resistance in glioblastomas.Herein,we report a robust time-resolved photoluminescence platform for identifying AAG inhibitors with improved sensitivity compared to conventional steady-state spectroscopic methods.As a proof-of-concept,this assay was used to screen 1440 food and drug administration-approved drugs against AAG,resulting in the repurposing of sunitinib as a potential AAG inhibitor.Sunitinib restored glioblastoma(GBM)cancer cell sensitivity to TMZ,inhibited GBM cell proliferation and stem cell characteristics,and induced GBM cell cycle arrest.Overall,this strategy offers a new method for the rapid identification of small-molecule inhibitors of BER enzyme activities that can prevent false negatives due to a fluorescent background.展开更多
We report the characterization of a uracil-DNA glycosylase（UDG） from the hyperthermophilic archaea Pyrococcus furiosus（P, furiosus）. P. furiosus UDG（PfUDG） has high sequence similarity to the families IV and V U...We report the characterization of a uracil-DNA glycosylase（UDG） from the hyperthermophilic archaea Pyrococcus furiosus（P, furiosus）. P. furiosus UDG（PfUDG） has high sequence similarity to the families IV and V UDGs（thermostable UDG family and PaUDG-b family）. PfUDG excises uracil from various DNA substrates with the following order： U/T=U/C〉U/G=U/AP=U/-〉U/U=U/I=U/A. The optimal temperature and pH value for uracil exci- sion by PfUDG are 70 ℃ and 9.0, respectively. The removal of U is inhibited by the divalent ions of Fe, Ca, Zn, Cu, Co, Ni and Mn, as well as a high concentration of NaC1. The phosphorothioates near uracil strongly inhibit the exci- sion of uracil by PfUDG. Interestingly, pfuDNA（Pyrococcusfuriosus DNA） polymerase, which tightly binds the ura- cil-carrying oligonucleotide, does not inhibit the excision by Pfl.IDG, suggesting PfUDG in vivo functions as the re- pair enzyme to excise uracil damage in genome.展开更多
目的本研究首先观察N-烷基嘧啶DNA糖基化酶(MPG)在人体骨肉瘤中的表达特点及其与患者预后的关系,进而构建复制缺陷型腺病毒MPG表达载体,探讨人骨肉瘤细胞HOS过表达MPG及其对DNA损伤药物MMS,MNNG和TMZ敏感性的影响。方法应用免疫组化方...目的本研究首先观察N-烷基嘧啶DNA糖基化酶(MPG)在人体骨肉瘤中的表达特点及其与患者预后的关系,进而构建复制缺陷型腺病毒MPG表达载体,探讨人骨肉瘤细胞HOS过表达MPG及其对DNA损伤药物MMS,MNNG和TMZ敏感性的影响。方法应用免疫组化方法检测60例骨肉瘤组织和3株骨肉瘤细胞中MPG的表达。按染色强度将其分为低表达组和高表达组,统计分析它们与临床病理及患者预后的关系。应用流式细胞术、蛋白印迹和HEX标记寡核苷酸方法确定MPG腺病毒表达载体Ad5 HA-MPG在人体骨肉瘤细胞HOS中的感染效率,MPG蛋白表达和MPG酶活性;MTS、SRB和[3H]胸腺嘧啶掺入法检测细胞存活;PE-Annexinv/7-AAD流式细胞术检测细胞凋亡。结果3株骨肉瘤细胞MPG均呈弱阳性表达。60例骨肉瘤中MPG 40例(65%)为高表达,MPG表达和WHO分型和患者预后显著相关。10 MO I Ad5 HA-MPG可使90%以上HOS感染,感染细胞高表达MPG并具有MPG酶活性。MPG过表达HOS显著地提高DNA损伤性化疗药物MMS、MNNG和TMZ的敏感性,其IC50值分别下降了6.0、4.5和2.5倍。结论Ad5 HA-MPG瞬时MPG过表达,可能是一种提高骨肉瘤细胞对DNA损伤性化疗药物敏感性的潜在治疗方法。展开更多
基金funded by the National Natural Science Foundation of China(Grant No.32188102 to L.X),Hainan Yazhou Bay Seed Lab(Grant No.B23CJ0208 to L.X)the Central Public-interest Scientific Institution Basal Research Fund(Grant No.ZDXM2308 to L.X)National Engineering Research Centre of Crop Molecular Breeding.
文摘Engineering of a new type of plant base editor for simultaneous adenine transition and transversion within the editing window will greatly expand the scope and potential of base editing in directed evolution and crop improvement.Here,we isolated a rice endogenous hypoxanthine excision protein,N-methylpurine DNA glycosylase(OsMPG),and engineered two plant A-to-K(K=G or T)base editors,rAKBE01 and rAKBE02,for simultaneous adenine transition and transversion base editing in rice by fusing OsMPG or its mutant mOsMPG to a plant adenine transition base editor,ABE8e.We further coupled either OsMPG or mOsMPG with a transactivation factor VP64 to generate rAKBE03 and rAKBE04,respectively.Testing these four rAKBEs,at five endogenous loci in rice protoplasts,indicated that rAKBE03 and rAKBE04 enabled higher levels of A-to-G base transitions when compared to ABE8e and ABE8e-VP64.Furthermore,whereas rAKBE01 only enabled A-to-C/T editing at one endogenous locus,in comparison with rAKBE02 and rAKBE03,rAKBE04 could significantly improve the A-to-C/T base transversion efficiencies by up to 6.57-and 1.75-fold in the rice protoplasts,respectively.Moreover,although no stable lines with A-to-C transversion were induced by rAKBE01 and rAKBE04,rAKBE04 could enable simultaneous A-to-G and A-to-T transition and transversion base editing,at all the five target loci,with the efficiencies of A-to-G transition and A-to-T transversion editing ranging from 70.97 to 92.31%and 1.67 to 4.84%in rice stable lines,respectively.Together,these rAKBEs enable different portfolios of editing products and,thus,now expands the potential of base editing in diverse application scenario for crop improvement.
基金supported by the Science and Technology Development Fund(Grant Nos.:0007/2020/A1 and 0020/2022/A1)the State Key Laboratory of Quality Research in Chinese Medicine,University of Macao(Grant No.:SKL-QRCM(UM)-2020-2022)+4 种基金the University of Macao(Grant Nos.:MYRG2019-00002-ICMS and MYRG2020-00017-ICMS)2022 Internal Research Grant of SKLQRCM(University of Macao)(Grant No.:QRCM-IRG2022-011)the National Natural Science Foundation of China(Grant No.:22101230)the Natural Science Basic Research Program of Shaanxi(Grant No.:2021JQ-089)the Natural Science Foundation of Chongqing,China(Grant No.:cstc2021jcyj-msxmX0659).
文摘Temozolomide(TMZ)is an anticancer agent used to treat glioblastoma,typically following radiation therapy and/or surgical resection.However,despite its effectiveness,at least 50%of patients do not respond to TMZ,which is associated with repair and/or tolerance of TMZ-induced DNA lesions.Studies have demonstrated that alkyladenine DNA glycosylase(AAG),an enzyme that triggers the base excision repair(BER)pathway by excising TMZ-induced N3-methyladenine(3meA)and N7-methylguanine lesions,is overexpressed in glioblastoma tissues compared to normal tissues.Therefore,it is essential to develop a rapid and efficient screening method for AAG inhibitors to overcome TMZ resistance in glioblastomas.Herein,we report a robust time-resolved photoluminescence platform for identifying AAG inhibitors with improved sensitivity compared to conventional steady-state spectroscopic methods.As a proof-of-concept,this assay was used to screen 1440 food and drug administration-approved drugs against AAG,resulting in the repurposing of sunitinib as a potential AAG inhibitor.Sunitinib restored glioblastoma(GBM)cancer cell sensitivity to TMZ,inhibited GBM cell proliferation and stem cell characteristics,and induced GBM cell cycle arrest.Overall,this strategy offers a new method for the rapid identification of small-molecule inhibitors of BER enzyme activities that can prevent false negatives due to a fluorescent background.
基金Supported by the National High Technology Research and Development Program of China(No.2006AA02Z108)the National Basic Research Program of China(No.2009CB118906)the National Natural Science Foundation of China(Nos.30700131,30870512)
文摘We report the characterization of a uracil-DNA glycosylase（UDG） from the hyperthermophilic archaea Pyrococcus furiosus（P, furiosus）. P. furiosus UDG（PfUDG） has high sequence similarity to the families IV and V UDGs（thermostable UDG family and PaUDG-b family）. PfUDG excises uracil from various DNA substrates with the following order： U/T=U/C〉U/G=U/AP=U/-〉U/U=U/I=U/A. The optimal temperature and pH value for uracil exci- sion by PfUDG are 70 ℃ and 9.0, respectively. The removal of U is inhibited by the divalent ions of Fe, Ca, Zn, Cu, Co, Ni and Mn, as well as a high concentration of NaC1. The phosphorothioates near uracil strongly inhibit the exci- sion of uracil by PfUDG. Interestingly, pfuDNA（Pyrococcusfuriosus DNA） polymerase, which tightly binds the ura- cil-carrying oligonucleotide, does not inhibit the excision by Pfl.IDG, suggesting PfUDG in vivo functions as the re- pair enzyme to excise uracil damage in genome.
文摘目的本研究首先观察N-烷基嘧啶DNA糖基化酶(MPG)在人体骨肉瘤中的表达特点及其与患者预后的关系,进而构建复制缺陷型腺病毒MPG表达载体,探讨人骨肉瘤细胞HOS过表达MPG及其对DNA损伤药物MMS,MNNG和TMZ敏感性的影响。方法应用免疫组化方法检测60例骨肉瘤组织和3株骨肉瘤细胞中MPG的表达。按染色强度将其分为低表达组和高表达组,统计分析它们与临床病理及患者预后的关系。应用流式细胞术、蛋白印迹和HEX标记寡核苷酸方法确定MPG腺病毒表达载体Ad5 HA-MPG在人体骨肉瘤细胞HOS中的感染效率,MPG蛋白表达和MPG酶活性;MTS、SRB和[3H]胸腺嘧啶掺入法检测细胞存活;PE-Annexinv/7-AAD流式细胞术检测细胞凋亡。结果3株骨肉瘤细胞MPG均呈弱阳性表达。60例骨肉瘤中MPG 40例(65%)为高表达,MPG表达和WHO分型和患者预后显著相关。10 MO I Ad5 HA-MPG可使90%以上HOS感染,感染细胞高表达MPG并具有MPG酶活性。MPG过表达HOS显著地提高DNA损伤性化疗药物MMS、MNNG和TMZ的敏感性,其IC50值分别下降了6.0、4.5和2.5倍。结论Ad5 HA-MPG瞬时MPG过表达,可能是一种提高骨肉瘤细胞对DNA损伤性化疗药物敏感性的潜在治疗方法。
