Single-base editors,including cytosine base editors(CBEs)and adenine base editors(ABEs),facilitate accurate C·G to T·A and A·T to G·C,respectively,holding promise for the precise modeling and treat...Single-base editors,including cytosine base editors(CBEs)and adenine base editors(ABEs),facilitate accurate C·G to T·A and A·T to G·C,respectively,holding promise for the precise modeling and treatment of human hereditary disorders.Efficient base editing and expanded base conversion range have been achieved in human cells through base editors fusing with Rad51 DNA binding domain(Rad51DBD),such as hyA3A-BE4max.Here,we show that hyA3A-BE4max catalyzes C-to-T substitution in the zebrafish genome and extends editing positions(C_(12)-C_(16))proximal to the protospacer adjacent motif.We develop a codon-optimized counterpart zhyA3A-CBE5,which exhibits substantially high C-to-T conversion with 1.59-to 3.50-fold improvement compared with the original hyA3A-BE4max.With these tools,disease-relevant hereditary mutations can be more efficaciously generated in zebrafish.We introduce human genetic mutation rpl11^(Q42*)and abcc6a^(R1463C) by zhyA3A-CBE5 in zebrafish,mirroring Diamond-Blackfan anemia and Pseudoxanthoma Elasticum,respectively.Our study expands the base editing platform targeting the zebrafish genomic landscape and the application of single-base editors for disease modeling and gene function study.展开更多
Cerebral autosomal dominant arteriopathy with subcortical infarcts and leukoencephalopathy (CADASIL) is a monogenic small vessel disease caused by mutations in the NOTCH3 gene. However, the pathogenesis of CADASIL rem...Cerebral autosomal dominant arteriopathy with subcortical infarcts and leukoencephalopathy (CADASIL) is a monogenic small vessel disease caused by mutations in the NOTCH3 gene. However, the pathogenesis of CADASIL remains unclear, and patients have limited treatment options. Here, we use human induced pluripotent stem cells (hiPSCs) generated from the peripheral blood mononuclear cells of a patient with CADASIL carrying a heterozygous NOTCH3 mutation (c.1261C>T, p.R421C) to develop a disease model. The correction efficiency of different adenine base editors (ABEs) is tested using the HEK293T-NOTCH3 reporter cell line. ABEmax is selected based on its higher efficiency and minimization of predicted off-target effects. Vascular smooth muscle cells (VSMCs) differentiated from CADASIL hiPSCs show NOTCH3 deposition and abnormal actin cytoskeleton structure, and the abnormalities are recovered in corrected hiPSC-derived VSMCs. Furthermore, CADASIL blood vessel organoids generated for in vivo modeling show altered expression of genes related to disease phenotypes, including the downregulation of cell adhesion, extracellular matrix organization, and vessel development. The dual adeno-associated virus (AAV) split-ABEmax system is applied to the genome editing of vascular organoids with an average editing efficiency of 8.82%. Collectively, we present potential genetic therapeutic strategies for patients with CADASIL using blood vessel organoids and the dual AAV split-ABEmax system.展开更多
The clustered regularly interspaced short palindromic repeats(CRISPR)–CRISPR-associated protein(Cas) system has been widely used for genome editing. In this system, the cytosine base editor(CBE) and adenine base edit...The clustered regularly interspaced short palindromic repeats(CRISPR)–CRISPR-associated protein(Cas) system has been widely used for genome editing. In this system, the cytosine base editor(CBE) and adenine base editor(ABE) allow generating precise and irreversible base mutations in a programmable manner and have been used in many different types of cells and organisms. However, their applications are limited by low editing efficiency at certain genomic target sites or at specific target cytosine(C) or adenine(A) residues. Using a strategy of combining optimized synergistic core components, we developed a new multiplex super-assembled ABE(sABE) in rice that showed higher base-editing efficiency than previously developed ABEs. We also designed a new type of nuclear localization signal(NLS) comprising a FLAG epitope tag with four copies of a codon-optimized NLS(F4NLS^(r2)) to generate another ABE named F4NLS-sABE. This new NLS increased editing efficiency or edited additional A at several target sites. A new multiplex super-assembled CBE(sCBE) and F4NLS^(r2) involved F4NLS-sCBE were also created using the same strategy. F4NLS-sCBE was proven to be much more efficient than sCBE in rice. These optimized base editors will serve as powerful genome-editing tools for basic research or molecular breeding in rice and will provide a reference for the development of superior editing tools for other plants or animals.展开更多
Base editing,the targeted introduction of point mutations into cellular DNA,holds promise for improving genome-scale functional genome screening to single-nucleotide resolution.Current efforts in prokaryotes,however,r...Base editing,the targeted introduction of point mutations into cellular DNA,holds promise for improving genome-scale functional genome screening to single-nucleotide resolution.Current efforts in prokaryotes,however,remain confined to loss-of-function screens using the premature stop codons-mediated gene inactivation library,which falls far short of fully releasing the potential of base editors.Here,we developed a base editor-mediated functional single nucleotide variant screening pipeline in Escherichia coli.We constructed a library with 31,123 sgRNAs targeting 462 stress response-related genes in E.coli,and screened for adaptive mutations under isobutanol and furfural selective conditions.Guided by the screening results,we successfully identified several known and novel functional mutations.Our pipeline might be expanded to the optimization of other phenotypes or the strain engineering in other microorganisms.展开更多
Halomonas bluephagenesis TD serves as an exceptional chassis for next generation industrial biotechnology to produce various products.However,the simultaneous editing of multiple loci in H.bluephagenesis TD remains a ...Halomonas bluephagenesis TD serves as an exceptional chassis for next generation industrial biotechnology to produce various products.However,the simultaneous editing of multiple loci in H.bluephagenesis TD remains a significant challenge.Herein,we report the development of a multiple loci genome editing system,named CRISPR-deaminase-assisted base editor(CRISPR-BE)in H.bluephagenesis TD.This system comprises two components:a cytidine(CRISPR-cBE)and an adenosine(CRISPR-aBE)deaminase-based base editor.CRISPR-cBE can introduce a cytidine to thymidine mutation with an efficiency of up to 100%within a 7-nt editing window in H.bluephagenesis TD.Similarly,CRISPR-aBE demonstrates an efficiency of up to 100%in converting adenosine to guanosine mutation within a 7-nt editing window.CRISPR-cBE has been further validated and successfully employed for simultaneous multiplexed editing in H.bluephagenesis TD.Our findings reveal that CRISPR-cBE efficiently inactivated all six copies of the IS1086 gene simultaneously by introducing stop codon.This system achieved an editing efficiency of 100%and 41.67%in inactivating two genes and three genes,respectively.By substituting the Pcas promoter with the inducible promoter PMmp1,we optimized CRISPR-cBE system and ultimately achieved 100%editing efficiency in inactivating three genes.In conclusion,our research offers a robust and efficient method for concurrently modifying multiple loci in H.bluephagenesis TD,opening up vast possibilities for industrial applications in the future.展开更多
Bacterial blight(BB),caused by Xanthomonas oryzae pathovar oryzae(Xoo),poses a significant threat to rice production,particularly in Asia and West Africa.Breeding resistance against BB in elite rice varieties is cruci...Bacterial blight(BB),caused by Xanthomonas oryzae pathovar oryzae(Xoo),poses a significant threat to rice production,particularly in Asia and West Africa.Breeding resistance against BB in elite rice varieties is crucial to advancing rice breeding program and supporting smallholder farmers.Transcription Activator-Like effectors(TALes)are key virulence factors in Xoo,with some targeting the susceptibility(S)genes such as the sugar transporter SWEET genes in rice.Among these,SWEET14 is an important S gene,with its promoter bound by the TALe TalC which exists across all sequenced African Xoo isolates.In the present study,we utilized CRISPR/Cas9-based cytidine and adenine base editors to alter the effector binding element(EBE)of TalC in the promoter of SWEET14 in rice cultivars Kitaake,IR24,and Zhonghua 11.Mutations with C to T changes in EBE led to reduced SWEET14 induction by TalC-containing Xoo strains,resulting in resistance to African Xoo isolates reliant on TalC for virulence.Conversely,A to G changes retained SWEET14 inducibility and susceptibility to Xoo in edited lines.Importantly,no off-target mutations were detected at predicted sites,and the edited lines exhibited no obvious defects in major agronomic traits in Kitaake.These results underscore the effectiveness of base editing systems for both molecular biology research and crop improvement endeavors.展开更多
Mutations in the Rhodopsin(RHO)gene are the main cause of autosomal dominant retinitis pigmentosa(adRP),84%of which are pathogenic gain-of-function point mutations.Treatment strategies for adRP typically involve silen...Mutations in the Rhodopsin(RHO)gene are the main cause of autosomal dominant retinitis pigmentosa(adRP),84%of which are pathogenic gain-of-function point mutations.Treatment strategies for adRP typically involve silencing or ablating the pathogenic allele,while normal RHO protein replacement has no meaningful therapeutic benefit.Here,we present an adenine base editor(ABE)-mediated therapeutic approach for adRP caused by RHO point mutations in vivo.The correctable pathogenic mutations are screened and verified,including T17M,Q344ter,and P347L.Two adRP animal models are created carrying the class 1(Q344ter)and class 2(T17M)mutations,and dual AAV-delivered ABE can effectively repair both mutations in vivo.The early intervention of ABE8e efficiently corrects the Q344ter mutation that causes a severe form of adRP,delays photoreceptor death,and restores retinal function and visual behavior.These results suggest that ABE is a promising alternative to treat RHO mutation-associated adRP.Our work provides an effective spacer-mediated point mutation correction therapy for dominantly inherited ocular disorders.展开更多
Single-nucleotide variants account for about half of known pathogenic genetic variants in human.Genome editing strategies by reversing pathogenic point mutations with minimum side effects have great therapeutic potent...Single-nucleotide variants account for about half of known pathogenic genetic variants in human.Genome editing strategies by reversing pathogenic point mutations with minimum side effects have great therapeutic potential and are now being actively pursued.The emerge of precise and effcient genome editing strategies such as base editing and prime editing provide powerful tools for nucleotide conversion without inducing double-stranded DNA breaks(DSBs),which have shown great potential for curing genetic disorders.A diverse toolkit of base editors has been devel-oped to improve the editing effciency and accuracy in different context of application.Here,we summarized the evolving of base editors(BEs),their limitations and future perspective of base editing-based therapeutic strategies.展开更多
Targeted point mutagenesis through homologous recombination has been widely used in genetic studies and holds considerable promise for repairing disease- causing mutations in patients. However, problems such as mosaic...Targeted point mutagenesis through homologous recombination has been widely used in genetic studies and holds considerable promise for repairing disease- causing mutations in patients. However, problems such as mosaicism and low mutagenesis efficiency continue to pose challenges to clinical applicaUon of such approaches. Recently, a base editor （BE） system built on cytidine （C） deaminase and CRISPR/Cas9 technology was developed as an alternative method for targeted point mutagenesis in plant, yeast, and human cells. Base editors convert C in the deamination window to thymidine （T） efficiently, however, it remains unclear whether targeted base editing in mouse embryos is feasible. In this report, we generated a modified high- fidelity version of base editor 2 （HF2-BE2）, and investigated its base editing efficacy in mouse embryos. We found that HF2-BE2 could convert C to T efficiently, with up to 100% biallelic mutation efficiency in mouse embryos. Unlike BE3, HF2-BE2 could convert C to T on both the target and non-target strand, expanding the editing scope of base editors. Surprisingly, we found HF2-BE2 could also deaminate C that was proximal to the gRNA-binding region. Taken together, our work demonstrates the feasibility of generating point mutations in mouse by base editing, and underscores the need to carefully optimize base editing systems in order to eliminate proximal-site deamination.展开更多
Exploiting novel endogenous glyphosate-tolerant alleles is highly desirable and has promising potential for weed control in rice breeding. Here,through fusions of different effective cytosine and adenine deaminases wi...Exploiting novel endogenous glyphosate-tolerant alleles is highly desirable and has promising potential for weed control in rice breeding. Here,through fusions of different effective cytosine and adenine deaminases with nCas9-NG, we engineered an effective surrogate two-component composite base editing system, STCBE-2, with improved C-to-T and A-to-G base editing efficiency and expanded the editing window. Furthermore,we targeted a rice endogenous OsEPSPS gene for artificial evolution through STCBE-2-mediated near-saturated mutagenesis. After hygromycin and glyphosate selection, we identified a novel OsEPSPS allele with an Asp-213-Asn(D213N)mutation(OsEPSPS-D213N) in the predicted glyphosate-binding domain, which conferred rice plants reliable glyphosate tolerance and had not been reported or applied in rice breeding. Collectively, we developed a novel dual base editor which will be valuable for artificial evolution of important genes in crops. And the novel glyphosate-tolerant rice germplasm generated in this study will benefit weeds management in rice paddy fields.展开更多
Cytosine and adenine base editors are promising new tools for introducing precise genetic modifications that are required to generate disease models and to improve traits in pigs. Base editors can catalyze the convers...Cytosine and adenine base editors are promising new tools for introducing precise genetic modifications that are required to generate disease models and to improve traits in pigs. Base editors can catalyze the conversion of C→T(C>T) or A→G(A>G) in the target site through a single guide RNA. Injection of base editors into the zygote cytoplasm can result in the production of offspring with precise point mutations, but most F0 are mosaic, and breeding of F1 heterozygous pigs is time-intensive. Here, we developed a method called germinal vesicle oocyte base editing(GVBE) to produce point mutant F0 porcine embryos by editing the maternal alleles during the GV to MⅡ transition. Injection of cytosine base editor 3(BE3) mRNA and X-linked Dmdspecific guide RNAs into GVoocytes efficiently edited maternal Dmd during in vitro maturation and did not affect the maturation potential of the oocytes. The edited MⅡ oocytes developed into blastocysts after parthenogenetic activation(PA) or in vitro fertilization(IVF). However, BE3 may reduce the developmental potential of IVF blastocysts from 31.5%±0.8% to 20.4%±2.1%. There 40%–78.3% diploid PA blastocysts had no more than two different alleles, including up to 10% embryos that had only C>T mutation alleles. Genotyping of IVF blastocysts indicated that over 70% of the edited embryos had one allele or two different alleles of Dmd. Since the male embryos had only a copy of Dmd allele, all five(5/19) F0 male embryos are homozygous and three of them were Dmd precise C>T mutation. Nine(9/19) female IVF embryos had two different alleles including a WT and a C>T mutation. DNA sequencing showed that some of them might be heterozygous embryos. In conclusion, the GVBE method is a valuable method for generating F0 embryos with maternal point mutated alleles in a single step.展开更多
Clustered regularly interspaced short palindromic repeats(CRISPR)—CRISPR-associated protein(Cas)and base editors are fundamental tools in plant genome editing.Cas9 from Streptococcus pyogenes(SpCas9),recognizing an N...Clustered regularly interspaced short palindromic repeats(CRISPR)—CRISPR-associated protein(Cas)and base editors are fundamental tools in plant genome editing.Cas9 from Streptococcus pyogenes(SpCas9),recognizing an NGG protospacer adjacent motif(PAM),is a widely used nuclease for genome editing in living cells.Cas12a nucleases,targeting T-rich PAMs,have also been recently demonstrated in several plant species.Furthermore,multiple Cas9 and Cas12a engineered variants and orthologs,with different PAM recognition sites,editing efficiencies and fidelity,have been explored in plants.These RNA-guided sequence-specific nucleases(SSN)generate double-stranded breaks(DSBs)in DNA,which trigger non-homologous end-joining(NHEJ)repair or homology-directed repair(HDR),resulting in insertion and deletion(indel)mutations or precise gene replacement,respectively.Alternatively,genome editing can be achieved by base editors without introducing DSBs.So far,several base editors have been applied in plants to introduce C-to-T or A-to-G transitions,but they are still undergoing improvement in editing window size,targeting scope,off-target effects in DNA and RNA,product purity and overall activity.Here,we summarize recent progress on the application of Cas nucleases,engineered Cas variants and base editors in plants.展开更多
The CRISPR/Cas9-mediated base editing technology can efficiently generate point mutations in the genome without introducing a double-strand break(DSB)or supplying a DNA donor template for homology-directed repair(HDR)...The CRISPR/Cas9-mediated base editing technology can efficiently generate point mutations in the genome without introducing a double-strand break(DSB)or supplying a DNA donor template for homology-directed repair(HDR).In this study,adenine base editors(ABEs)were used for rapid generation of precise point mutations in two distinct genes,OsWSL5,and OsZEBRA3(Z3),in both rice protoplasts and regenerated plants.The precisely engineered point mutations were stably inherited to subsequent generations.These single nucleotide alterations resulted in single amino acid changes and associated wsl5 and z3 phenotypes as evidenced by white stripe leaf and light green/dark green leaf pattern,respectively.Through selfing and genetic segregation,transgene-free,base edited wsl5 and z3 mutants were obtained in a short period of time.We noticed a novel mutation(V540A)in Z3 locus could also mimic the phenotype of Z3 mutation(S542P).Furthermore,we observed unexpected non-A/G or T/C mutations in the ABE editing window in a few of the edited plants.The ABE vectors and the method from this study could be used to simultaneously generate point mutations in multiple target genes in a single transformation and serve as a useful base editing tool for crop improvement as well as basic studies in plant biology.展开更多
Approximately 140 million people worldwide are homozygous carriers of APOE4(ε4),a strong genetic risk factor for late onset familial and sporadic Alzheimer’s disease(AD),91%of whom will develop AD at earlier age tha...Approximately 140 million people worldwide are homozygous carriers of APOE4(ε4),a strong genetic risk factor for late onset familial and sporadic Alzheimer’s disease(AD),91%of whom will develop AD at earlier age than heterozygous carriers and noncarriers.Susceptibility to AD could be reduced by targeted editing of APOE4,but a technical basis for controlling the off-target effects of base editors is necessary to develop low-risk personalized gene therapies.Here,we first screened eight cytosine base editor variants at four injection stages(from 1-to 8-cell stage),and found that FNLS-YE1 variant in 8-cell embryos achieved the comparable base conversion rate(up to 100%)with the lowest bystander effects.In particular,80%of AD-susceptibleε4 allele copies were converted to the AD-neutralε3 allele in humanε4-carrying embryos.Stringent control measures combined with targeted deep sequencing,whole genome sequencing,and RNA sequencing showed no DNA or RNA off-target events in FNLS-YE1-treated human embryos or their derived stem cells.Furthermore,base editing with FNLS-YE1 showed no effects on embryo development to the blastocyst stage.Finally,we also demonstrated FNLS-YE1 could introduce known protective variants in human embryos to potentially reduce human susceptivity to systemic lupus erythematosus and familial hypercholesterolemia.Our study therefore suggests that base editing with FNLS-YE1 can efficiently and safely introduce known preventive variants in 8-cell human embryos,a potential approach for reducing human susceptibility to AD or other genetic diseases.展开更多
APOBECs（apolipoprotein B mRNA editing enzyme, catalytic polypeptide-like） are a family of cytidine deaminases that prefer single-stranded nucleic acids as substrates. Besides their physiological functions,APOBEC fam...APOBECs（apolipoprotein B mRNA editing enzyme, catalytic polypeptide-like） are a family of cytidine deaminases that prefer single-stranded nucleic acids as substrates. Besides their physiological functions,APOBEC family members have been found to cause hypermutations of cancer genomes, which could be correlated with cancer development and poor prognosis. Recently, APOBEC family members have been combined with the versatile CRISPR/Cas9 system to perform targeted base editing or induce hypermutagenesis. This combination improved the CRISPR/Cas9-mediated gene editing at single-base precision, greatly enhancing its usefulness. Here, we review the physiological functions and structural characteristics of APOBEC family members and their roles as endogenous mutators that contribute to hypermutations during carcinogenesis. We also review the various iterations of the APOBEC-CRISPR/Cas9 gene-editing tools, pointing out their features and limitations as well as the possibilities for future developments.展开更多
基金supported by grants from Ministry of Science and Technology of the People's Republic of China(2018YFA0801004 and 2018YFA0800103)the National Natural Science Foundation of China(NSFC31530044,NSFC31970780,NSFC82202056).
文摘Single-base editors,including cytosine base editors(CBEs)and adenine base editors(ABEs),facilitate accurate C·G to T·A and A·T to G·C,respectively,holding promise for the precise modeling and treatment of human hereditary disorders.Efficient base editing and expanded base conversion range have been achieved in human cells through base editors fusing with Rad51 DNA binding domain(Rad51DBD),such as hyA3A-BE4max.Here,we show that hyA3A-BE4max catalyzes C-to-T substitution in the zebrafish genome and extends editing positions(C_(12)-C_(16))proximal to the protospacer adjacent motif.We develop a codon-optimized counterpart zhyA3A-CBE5,which exhibits substantially high C-to-T conversion with 1.59-to 3.50-fold improvement compared with the original hyA3A-BE4max.With these tools,disease-relevant hereditary mutations can be more efficaciously generated in zebrafish.We introduce human genetic mutation rpl11^(Q42*)and abcc6a^(R1463C) by zhyA3A-CBE5 in zebrafish,mirroring Diamond-Blackfan anemia and Pseudoxanthoma Elasticum,respectively.Our study expands the base editing platform targeting the zebrafish genomic landscape and the application of single-base editors for disease modeling and gene function study.
基金funded by the National Natural Science Foundation of China(31971365)the Guangdong Basic and Applied Basic Research Foundation(2020B1515120090)the Local Innovative and Research Teams Project of Guangdong Pearl River Talents Program(2019BT02Y276).
文摘Cerebral autosomal dominant arteriopathy with subcortical infarcts and leukoencephalopathy (CADASIL) is a monogenic small vessel disease caused by mutations in the NOTCH3 gene. However, the pathogenesis of CADASIL remains unclear, and patients have limited treatment options. Here, we use human induced pluripotent stem cells (hiPSCs) generated from the peripheral blood mononuclear cells of a patient with CADASIL carrying a heterozygous NOTCH3 mutation (c.1261C>T, p.R421C) to develop a disease model. The correction efficiency of different adenine base editors (ABEs) is tested using the HEK293T-NOTCH3 reporter cell line. ABEmax is selected based on its higher efficiency and minimization of predicted off-target effects. Vascular smooth muscle cells (VSMCs) differentiated from CADASIL hiPSCs show NOTCH3 deposition and abnormal actin cytoskeleton structure, and the abnormalities are recovered in corrected hiPSC-derived VSMCs. Furthermore, CADASIL blood vessel organoids generated for in vivo modeling show altered expression of genes related to disease phenotypes, including the downregulation of cell adhesion, extracellular matrix organization, and vessel development. The dual adeno-associated virus (AAV) split-ABEmax system is applied to the genome editing of vascular organoids with an average editing efficiency of 8.82%. Collectively, we present potential genetic therapeutic strategies for patients with CADASIL using blood vessel organoids and the dual AAV split-ABEmax system.
基金supported by the Beijing Scholars Program[BSP041]。
文摘The clustered regularly interspaced short palindromic repeats(CRISPR)–CRISPR-associated protein(Cas) system has been widely used for genome editing. In this system, the cytosine base editor(CBE) and adenine base editor(ABE) allow generating precise and irreversible base mutations in a programmable manner and have been used in many different types of cells and organisms. However, their applications are limited by low editing efficiency at certain genomic target sites or at specific target cytosine(C) or adenine(A) residues. Using a strategy of combining optimized synergistic core components, we developed a new multiplex super-assembled ABE(sABE) in rice that showed higher base-editing efficiency than previously developed ABEs. We also designed a new type of nuclear localization signal(NLS) comprising a FLAG epitope tag with four copies of a codon-optimized NLS(F4NLS^(r2)) to generate another ABE named F4NLS-sABE. This new NLS increased editing efficiency or edited additional A at several target sites. A new multiplex super-assembled CBE(sCBE) and F4NLS^(r2) involved F4NLS-sCBE were also created using the same strategy. F4NLS-sCBE was proven to be much more efficient than sCBE in rice. These optimized base editors will serve as powerful genome-editing tools for basic research or molecular breeding in rice and will provide a reference for the development of superior editing tools for other plants or animals.
基金supported by the National Key Research and Development Program of China (2018YFA0901500)the National Natural Science Foundation of China (U2032210)。
文摘Base editing,the targeted introduction of point mutations into cellular DNA,holds promise for improving genome-scale functional genome screening to single-nucleotide resolution.Current efforts in prokaryotes,however,remain confined to loss-of-function screens using the premature stop codons-mediated gene inactivation library,which falls far short of fully releasing the potential of base editors.Here,we developed a base editor-mediated functional single nucleotide variant screening pipeline in Escherichia coli.We constructed a library with 31,123 sgRNAs targeting 462 stress response-related genes in E.coli,and screened for adaptive mutations under isobutanol and furfural selective conditions.Guided by the screening results,we successfully identified several known and novel functional mutations.Our pipeline might be expanded to the optimization of other phenotypes or the strain engineering in other microorganisms.
基金supported by the National Natural Science Foundation of China(Grant No.32171415)the Chongqing Talents Top Youth Talent Program(No.CQYC202105065).
文摘Halomonas bluephagenesis TD serves as an exceptional chassis for next generation industrial biotechnology to produce various products.However,the simultaneous editing of multiple loci in H.bluephagenesis TD remains a significant challenge.Herein,we report the development of a multiple loci genome editing system,named CRISPR-deaminase-assisted base editor(CRISPR-BE)in H.bluephagenesis TD.This system comprises two components:a cytidine(CRISPR-cBE)and an adenosine(CRISPR-aBE)deaminase-based base editor.CRISPR-cBE can introduce a cytidine to thymidine mutation with an efficiency of up to 100%within a 7-nt editing window in H.bluephagenesis TD.Similarly,CRISPR-aBE demonstrates an efficiency of up to 100%in converting adenosine to guanosine mutation within a 7-nt editing window.CRISPR-cBE has been further validated and successfully employed for simultaneous multiplexed editing in H.bluephagenesis TD.Our findings reveal that CRISPR-cBE efficiently inactivated all six copies of the IS1086 gene simultaneously by introducing stop codon.This system achieved an editing efficiency of 100%and 41.67%in inactivating two genes and three genes,respectively.By substituting the Pcas promoter with the inducible promoter PMmp1,we optimized CRISPR-cBE system and ultimately achieved 100%editing efficiency in inactivating three genes.In conclusion,our research offers a robust and efficient method for concurrently modifying multiple loci in H.bluephagenesis TD,opening up vast possibilities for industrial applications in the future.
基金supported by a sub-award to the University of Missouri from the Heinrich Heine University of Dusseldorf funded by the Bill&Melinda Gates Foundation(OPP1155704)(Bing Yang)and the China Scholar Council(Chenhao Li,as a joint Ph.D.student).
文摘Bacterial blight(BB),caused by Xanthomonas oryzae pathovar oryzae(Xoo),poses a significant threat to rice production,particularly in Asia and West Africa.Breeding resistance against BB in elite rice varieties is crucial to advancing rice breeding program and supporting smallholder farmers.Transcription Activator-Like effectors(TALes)are key virulence factors in Xoo,with some targeting the susceptibility(S)genes such as the sugar transporter SWEET genes in rice.Among these,SWEET14 is an important S gene,with its promoter bound by the TALe TalC which exists across all sequenced African Xoo isolates.In the present study,we utilized CRISPR/Cas9-based cytidine and adenine base editors to alter the effector binding element(EBE)of TalC in the promoter of SWEET14 in rice cultivars Kitaake,IR24,and Zhonghua 11.Mutations with C to T changes in EBE led to reduced SWEET14 induction by TalC-containing Xoo strains,resulting in resistance to African Xoo isolates reliant on TalC for virulence.Conversely,A to G changes retained SWEET14 inducibility and susceptibility to Xoo in edited lines.Importantly,no off-target mutations were detected at predicted sites,and the edited lines exhibited no obvious defects in major agronomic traits in Kitaake.These results underscore the effectiveness of base editing systems for both molecular biology research and crop improvement endeavors.
基金funded by the National Key Research and Development Program of China(2023YFC2506100)the National Natural Science Foundation of China(31971365,32371509,32001063,and 82271688)+3 种基金the Local Innovative and Research Teams Project of Guangdong Pearl River Talents Program(2019BT02Y276)the Guangdong Basic and Applied Basic Research Foundation(2023A1515010176)the grant from MOE Key Laboratory of Gene Function and Regulation,the Guangzhou Science and Technology Planning Project(2023A04J1952)the Fundamental Research Funds for the Central Universities,Sun Yat-sen University(23ptpy59).
文摘Mutations in the Rhodopsin(RHO)gene are the main cause of autosomal dominant retinitis pigmentosa(adRP),84%of which are pathogenic gain-of-function point mutations.Treatment strategies for adRP typically involve silencing or ablating the pathogenic allele,while normal RHO protein replacement has no meaningful therapeutic benefit.Here,we present an adenine base editor(ABE)-mediated therapeutic approach for adRP caused by RHO point mutations in vivo.The correctable pathogenic mutations are screened and verified,including T17M,Q344ter,and P347L.Two adRP animal models are created carrying the class 1(Q344ter)and class 2(T17M)mutations,and dual AAV-delivered ABE can effectively repair both mutations in vivo.The early intervention of ABE8e efficiently corrects the Q344ter mutation that causes a severe form of adRP,delays photoreceptor death,and restores retinal function and visual behavior.These results suggest that ABE is a promising alternative to treat RHO mutation-associated adRP.Our work provides an effective spacer-mediated point mutation correction therapy for dominantly inherited ocular disorders.
基金supported by CAMS Innovation Fund for Medical Sciences(CIFMS,2022-I2M-1-024,2022-RC180-02 to Z.G.).
文摘Single-nucleotide variants account for about half of known pathogenic genetic variants in human.Genome editing strategies by reversing pathogenic point mutations with minimum side effects have great therapeutic potential and are now being actively pursued.The emerge of precise and effcient genome editing strategies such as base editing and prime editing provide powerful tools for nucleotide conversion without inducing double-stranded DNA breaks(DSBs),which have shown great potential for curing genetic disorders.A diverse toolkit of base editors has been devel-oped to improve the editing effciency and accuracy in different context of application.Here,we summarized the evolving of base editors(BEs),their limitations and future perspective of base editing-based therapeutic strategies.
基金This work was supported by the National Natural Science Foundation of China （Grant Nos. 91640119, 31601196, 81330055, 31371508, and 31671540）, the Natural Science Foundation of Guangdong Province （2016A030310206 and 2014A030312011）, the Science and Technology Planning Project of Guangdong Province （2015B020228002 and 2015A020212005）, the Guangzhou Science and Technology Project （201605030012 and 201707010085）, and the Fundamental Research Funds for the Central Universities （161gzd13 and 161gpy31）. We would also like to acknowledge the support of CA211653, CPRIT RP160462, the Welch Foundation Q-1673, and the C-BASS Shared Resource at the Dan L. Duncan Cancer Center （DLDCC） of Baylor College of Medicine （P30CA125123）.
文摘Targeted point mutagenesis through homologous recombination has been widely used in genetic studies and holds considerable promise for repairing disease- causing mutations in patients. However, problems such as mosaicism and low mutagenesis efficiency continue to pose challenges to clinical applicaUon of such approaches. Recently, a base editor （BE） system built on cytidine （C） deaminase and CRISPR/Cas9 technology was developed as an alternative method for targeted point mutagenesis in plant, yeast, and human cells. Base editors convert C in the deamination window to thymidine （T） efficiently, however, it remains unclear whether targeted base editing in mouse embryos is feasible. In this report, we generated a modified high- fidelity version of base editor 2 （HF2-BE2）, and investigated its base editing efficacy in mouse embryos. We found that HF2-BE2 could convert C to T efficiently, with up to 100% biallelic mutation efficiency in mouse embryos. Unlike BE3, HF2-BE2 could convert C to T on both the target and non-target strand, expanding the editing scope of base editors. Surprisingly, we found HF2-BE2 could also deaminate C that was proximal to the gRNA-binding region. Taken together, our work demonstrates the feasibility of generating point mutations in mouse by base editing, and underscores the need to carefully optimize base editing systems in order to eliminate proximal-site deamination.
基金partly funded by the National Natural Science Foundation of China (32188102 to LX)Hainan Yazhou Bay Seed Lab (B21HJ0215 to LX)+2 种基金the Central Public-Interest Scientific Institution-Based Research Fund (S2023ZD03 to LX)Key Laboratory of Gene Editing Technologies (Hainan), ChinaNational Engineering Research Center of Crop Molecular Breeding。
文摘Exploiting novel endogenous glyphosate-tolerant alleles is highly desirable and has promising potential for weed control in rice breeding. Here,through fusions of different effective cytosine and adenine deaminases with nCas9-NG, we engineered an effective surrogate two-component composite base editing system, STCBE-2, with improved C-to-T and A-to-G base editing efficiency and expanded the editing window. Furthermore,we targeted a rice endogenous OsEPSPS gene for artificial evolution through STCBE-2-mediated near-saturated mutagenesis. After hygromycin and glyphosate selection, we identified a novel OsEPSPS allele with an Asp-213-Asn(D213N)mutation(OsEPSPS-D213N) in the predicted glyphosate-binding domain, which conferred rice plants reliable glyphosate tolerance and had not been reported or applied in rice breeding. Collectively, we developed a novel dual base editor which will be valuable for artificial evolution of important genes in crops. And the novel glyphosate-tolerant rice germplasm generated in this study will benefit weeds management in rice paddy fields.
基金supported by the National Key R&D Program of China (2017YFC1001901 and 2017YFA0102801)the National Natural Science Foundation (31671540)+3 种基金the National Transgenic Major Program (2016ZX08006003-006)the Natural Science Foundation of Guangdong Province (2015A020212005 and 2014A030312011)the Key R&D Program of Guangdong Province (2018B020203003)the Guangzhou Science and Technology Project (201803010020)。
文摘Cytosine and adenine base editors are promising new tools for introducing precise genetic modifications that are required to generate disease models and to improve traits in pigs. Base editors can catalyze the conversion of C→T(C>T) or A→G(A>G) in the target site through a single guide RNA. Injection of base editors into the zygote cytoplasm can result in the production of offspring with precise point mutations, but most F0 are mosaic, and breeding of F1 heterozygous pigs is time-intensive. Here, we developed a method called germinal vesicle oocyte base editing(GVBE) to produce point mutant F0 porcine embryos by editing the maternal alleles during the GV to MⅡ transition. Injection of cytosine base editor 3(BE3) mRNA and X-linked Dmdspecific guide RNAs into GVoocytes efficiently edited maternal Dmd during in vitro maturation and did not affect the maturation potential of the oocytes. The edited MⅡ oocytes developed into blastocysts after parthenogenetic activation(PA) or in vitro fertilization(IVF). However, BE3 may reduce the developmental potential of IVF blastocysts from 31.5%±0.8% to 20.4%±2.1%. There 40%–78.3% diploid PA blastocysts had no more than two different alleles, including up to 10% embryos that had only C>T mutation alleles. Genotyping of IVF blastocysts indicated that over 70% of the edited embryos had one allele or two different alleles of Dmd. Since the male embryos had only a copy of Dmd allele, all five(5/19) F0 male embryos are homozygous and three of them were Dmd precise C>T mutation. Nine(9/19) female IVF embryos had two different alleles including a WT and a C>T mutation. DNA sequencing showed that some of them might be heterozygous embryos. In conclusion, the GVBE method is a valuable method for generating F0 embryos with maternal point mutated alleles in a single step.
基金Our plant genome editing research is supported by the National Science Foundation Plant Genome Research Program(IOS-1758745)USDA-NIFA Biotechnology Risk Assessment Research Program(2018-33522-28789)+1 种基金Foundation for Food and Agriculture Research(593603)Syngenta Biotechnology.
文摘Clustered regularly interspaced short palindromic repeats(CRISPR)—CRISPR-associated protein(Cas)and base editors are fundamental tools in plant genome editing.Cas9 from Streptococcus pyogenes(SpCas9),recognizing an NGG protospacer adjacent motif(PAM),is a widely used nuclease for genome editing in living cells.Cas12a nucleases,targeting T-rich PAMs,have also been recently demonstrated in several plant species.Furthermore,multiple Cas9 and Cas12a engineered variants and orthologs,with different PAM recognition sites,editing efficiencies and fidelity,have been explored in plants.These RNA-guided sequence-specific nucleases(SSN)generate double-stranded breaks(DSBs)in DNA,which trigger non-homologous end-joining(NHEJ)repair or homology-directed repair(HDR),resulting in insertion and deletion(indel)mutations or precise gene replacement,respectively.Alternatively,genome editing can be achieved by base editors without introducing DSBs.So far,several base editors have been applied in plants to introduce C-to-T or A-to-G transitions,but they are still undergoing improvement in editing window size,targeting scope,off-target effects in DNA and RNA,product purity and overall activity.Here,we summarize recent progress on the application of Cas nucleases,engineered Cas variants and base editors in plants.
基金This work was supported by National Science Foundation Plant Genome Research Program Grant No.1740874the USDA National Institute of Food and Agriculture and Hatch Appropriations under Project#PEN04659 and Accession#1016432 to Yinong Yang.
文摘The CRISPR/Cas9-mediated base editing technology can efficiently generate point mutations in the genome without introducing a double-strand break(DSB)or supplying a DNA donor template for homology-directed repair(HDR).In this study,adenine base editors(ABEs)were used for rapid generation of precise point mutations in two distinct genes,OsWSL5,and OsZEBRA3(Z3),in both rice protoplasts and regenerated plants.The precisely engineered point mutations were stably inherited to subsequent generations.These single nucleotide alterations resulted in single amino acid changes and associated wsl5 and z3 phenotypes as evidenced by white stripe leaf and light green/dark green leaf pattern,respectively.Through selfing and genetic segregation,transgene-free,base edited wsl5 and z3 mutants were obtained in a short period of time.We noticed a novel mutation(V540A)in Z3 locus could also mimic the phenotype of Z3 mutation(S542P).Furthermore,we observed unexpected non-A/G or T/C mutations in the ABE editing window in a few of the edited plants.The ABE vectors and the method from this study could be used to simultaneously generate point mutations in multiple target genes in a single transformation and serve as a useful base editing tool for crop improvement as well as basic studies in plant biology.
基金supported by Chinese National Science and Technology major project R&D Program of China(2018YFC2000101)Strategic Priority Research Program of Chinese Academy of Science(XDB32060000)+7 种基金National Natural Science Foundation of China(Grant Nos.31871502,31901047,31925016,91957122,82021001,and 31922048)Basic Frontier Scientific Research Program of Chinese Academy of Sciences From 0 to 1 original innovation project(ZDBS-LYSM001)Shanghai Municipal Science and Technology Major Project(2018SHZDZX05)Shanghai City Committee of Science and Technology Project(18411953700,18JC1410100,19XD1424400 and 19YF1455100)Innovative Research Team of High-Level Local Universities in Shanghai(SHSMU-ZDCX20212200 and SHSMU-ZLCX20210200)International Partnership Program of Chinese Academy of Sciences(153D31KYSB20170059)Postdoctoral Science Foundation of China(2020M681417 and 2021T140684)Sailing Program of Shanghai(21YF1453000)(to J.H.).
文摘Approximately 140 million people worldwide are homozygous carriers of APOE4(ε4),a strong genetic risk factor for late onset familial and sporadic Alzheimer’s disease(AD),91%of whom will develop AD at earlier age than heterozygous carriers and noncarriers.Susceptibility to AD could be reduced by targeted editing of APOE4,but a technical basis for controlling the off-target effects of base editors is necessary to develop low-risk personalized gene therapies.Here,we first screened eight cytosine base editor variants at four injection stages(from 1-to 8-cell stage),and found that FNLS-YE1 variant in 8-cell embryos achieved the comparable base conversion rate(up to 100%)with the lowest bystander effects.In particular,80%of AD-susceptibleε4 allele copies were converted to the AD-neutralε3 allele in humanε4-carrying embryos.Stringent control measures combined with targeted deep sequencing,whole genome sequencing,and RNA sequencing showed no DNA or RNA off-target events in FNLS-YE1-treated human embryos or their derived stem cells.Furthermore,base editing with FNLS-YE1 showed no effects on embryo development to the blastocyst stage.Finally,we also demonstrated FNLS-YE1 could introduce known protective variants in human embryos to potentially reduce human susceptivity to systemic lupus erythematosus and familial hypercholesterolemia.Our study therefore suggests that base editing with FNLS-YE1 can efficiently and safely introduce known preventive variants in 8-cell human embryos,a potential approach for reducing human susceptibility to AD or other genetic diseases.
基金supported by grants from the National Natural Science Foundation of China (Nos. 31600619 and 31600654)Shanghai Municipal Science and Technology Commission (Nos. 16PJ1407000 and 16PJ1407500)
文摘APOBECs（apolipoprotein B mRNA editing enzyme, catalytic polypeptide-like） are a family of cytidine deaminases that prefer single-stranded nucleic acids as substrates. Besides their physiological functions,APOBEC family members have been found to cause hypermutations of cancer genomes, which could be correlated with cancer development and poor prognosis. Recently, APOBEC family members have been combined with the versatile CRISPR/Cas9 system to perform targeted base editing or induce hypermutagenesis. This combination improved the CRISPR/Cas9-mediated gene editing at single-base precision, greatly enhancing its usefulness. Here, we review the physiological functions and structural characteristics of APOBEC family members and their roles as endogenous mutators that contribute to hypermutations during carcinogenesis. We also review the various iterations of the APOBEC-CRISPR/Cas9 gene-editing tools, pointing out their features and limitations as well as the possibilities for future developments.
