This study aimed to compare the efficiencies of clustered regulatory interspaced short palindromic repeat（CRISPR）/Cas9-mediated gene knock-ins with zinc finger nucleases（ZFNs） and transcription activator-like effe...This study aimed to compare the efficiencies of clustered regulatory interspaced short palindromic repeat（CRISPR）/Cas9-mediated gene knock-ins with zinc finger nucleases（ZFNs） and transcription activator-like effector nucleases（TALENs） in bovine and dairy goat fetal fibroblasts. To test the knock-in efficiency, a set of ZFNs and CRISPR/Cas9 plasmids were designed to edit the bovine myostatin（MSTN） gene at exon 2, while a set of TALENs and CRISPR/Cas9 plasmids were designed for editing the dairy goat β-casein gene at exon 2. Donor plasmids utilizing the ZFNs, TALENs, and CRISPR/Cas9 cutting sites were constructed in theGFP-PGK-Neo R plasmid background, including a 5′ and 3′ homologous arm flanking the genes humanized Fat-1（h Fat-1） or enhanced green fluorescent protein（eGFP）. Subsequently, the ZFNs, TALENs, or CRISPR/Cas9 and thehFat-1 or eGFP plasmids were co-transfected by electroporation into bovine and dairy goat fetal fibroblasts. After G418（Geneticin） selection, single cells were obtained by mouth pipetting, flow cytometry or a cell shove. The gene knock-in events were screened by PCR across the homologous arms. The results showed that in bovine fetal fibrobalsts, the efficiencies of ZFNs-mediated eGFP andhFat-1 gene knock-ins were 13.68 and 0%, respectively. The efficiencies of CRISPR/Cas9-mediated eGFP andhFat-1 gene knock-ins were 77.02 and 79.01%, respectively. The eGFP gene knock-in efficiency using CRISPR/Cas9 was about 5.6 times higher than when using the ZFNs gene editing system. Additionally, thehFat-1 gene knock-in was only obtained when using the CRISPR/Cas9 system. The difference of knockin efficiencies between the ZFNs and CRISPR/Cas9 systems were extremely significant（P〈0.01）. In the dairy goat fetal fibroblasts, the efficiencies of TALENs-mediated eGFP andhFat-1 gene knock-ins were 32.35 and 26.47%, respectively. Theefficiencies of eGFP and hFat-1 gene knock-ins using CRISPR/Cas9 were 70.37 and 74.29%, respectively. The knock-in efficiencies difference between the TALENs and CRISPR/Cas9 systems were extremely significant（P〈0.01）. This study demonstrated that CRISPR/Cas9 was more efficient at gene knock-ins in domesticated animal cells than ZFNs and TALENs. The CRISPR/Cas9 technology offers a new era of precise gene editing in domesticated animal cell lines.展开更多
Genetic pest control strategies based on precise sex separation and only releasing sterile males can be accomplished by site-specific genome editing.In the current study,we showed that the mutation of single-allele Px...Genetic pest control strategies based on precise sex separation and only releasing sterile males can be accomplished by site-specific genome editing.In the current study,we showed that the mutation of single-allele Pxfl(2)d can significantly impair the normal mating behavior and testis development in male adults of the notorious cruciferous insect pest Plutella xylostella,in addition to its known functions in the ovarian development in female adults and egg hatching.Subsequent CRISPR/Cas9-based knock-in experiments revealed that site-specific integration of an exogenous green fluorescent protein(GFP)gene into autosomal Pxfl(2)d for labelling mutants could be achieved.However,this gene is not a suitable target for GFP insertion to establish a genetically stable knock-in strain because of the severe decline in reproductive capacity.We further screened for the W-chromosome-linked and Z-chromosome-linked regions to test the knock-in efficiency mediated by CRISPR/Cas9.The results verified that both types of chromosomes can be targeted for the site-specific insertion of exogenous sequences.We ultimately obtained a homozygous knock-in strain with the integration of both Cas9 and cyan fluorescent protein(CFP)expression cassettes on a Z-linked region in P.xylostella,which can also be used for early sex detection.By injecting the sgRNA targeting Pxfl(2)d alone into the eggs laid by female adults of the Z-Cas9-CFP strain,the gene editing efficiency reached 29.73%,confirming the success of expressing a functional Cas9 gene.Taken together,we demonstrated the feasibility of the knock-in of an exogenous gene to different genomic regions in P.xylostella,while the establishment of a heritable strain required the positioning of appropriate sites.This study provides an important working basis and technical support for further developing genetic strategies for insect pest control.展开更多
Huntington＇s disease （HD） is an inherited autosomal dominant neurodegenerative disease characterized by pro- gressive motor deficits, cognitive decline, and psychiatric symptoms. It is caused by a pathological expa...Huntington＇s disease （HD） is an inherited autosomal dominant neurodegenerative disease characterized by pro- gressive motor deficits, cognitive decline, and psychiatric symptoms. It is caused by a pathological expansion of CAG trinucleotide repeats in exon 1 of the HD gene, resulting in the translation of a mutant form of huntingtin protein （mutant Htt） with an expanded polyglutamine domain in the N-terminal region [1 ]. Despite great progress in understanding the pathogenesis of HD using multiple mouse models, the exact mechanisms by which mutant Htt induces neuronal dysfunction and death are still not completely clear, and there is no curative treatment for this disease. An important reason is that the mouse, which is the most widely used animal model in HD research, differs from the human in many aspects, including the physiology, drug metabolism, blood-brain barrier, life span, brain volume, and neuroanatomical organization [2]. Thus, it is necessary to establish HD models with higher species than rodents, such as the dog, pig, and non- human primate, so as to bridge the gap between preclinical mouse models and clinical studies.展开更多
Inducible expression systems are indispensable for precise regulation and in-depth analysis of biological process.Binary Tet-On system has been widely employed to regulate transgenic expression by doxycycline.Previous...Inducible expression systems are indispensable for precise regulation and in-depth analysis of biological process.Binary Tet-On system has been widely employed to regulate transgenic expression by doxycycline.Previous pig models with tetracycline regulatory elements were generated through random integration.This process often resulted in uncertain expression and unpredictable phenotypes,thus hindering their applications.Here,by precise knock-in of binary Tet-On 3G elements into Rosa26 and Hipp11 locus,respectively,a double knock-in reporter pig model was generated.We characterized excellent properties of this system for controllable transgenic expression both in vitro and in vivo.Two att P sites were arranged to flank the td Tomato to switch reporter gene.Single or multiple gene replacement was efficiently and faithfully achieved in fetal fibroblasts and nuclear transfer embryos.To display the flexible application of this system,we generated a pig strain with Dox-inducing h KRASexpression through phiC31 integrase-mediated cassette exchange.After eight months of Dox administration,squamous cell carcinoma developed in the nose,mouth,and scrotum,which indicated this pig strain could serve as an ideal large animal model to study tumorigenesis.Overall,the established pig models with controllable and switchable transgene expression system will provide a facilitating platform for transgenic and biomedical research.展开更多
Background Megalencephalic leukoencephalopathy with subcortical cysts(MLC)is a rare neurological degenerative disorder caused by the mutations of MLC1 or GLIALCAM with autosomal recessive or autosomal dominant inherit...Background Megalencephalic leukoencephalopathy with subcortical cysts(MLC)is a rare neurological degenerative disorder caused by the mutations of MLC1 or GLIALCAM with autosomal recessive or autosomal dominant inheritance and a different prognosis,characterized by macrocephaly,delayed motor and cognitive development,and bilateral abnormal signals in cerebral white matter(WM)with or without cysts on magnetic resonance imaging(MRI).This study aimed to reveal the clinical and genetic features of MLC patients with GLIALCAM mutations and to explore the brain pathological characteristics and prognosis of mouse models with different modes of inheritance.Methods Clinical information and peripheral venous blood were collected from six families.Genetic analysis was performed by Sanger sequencing of GLIALCAM.Glialcam^(Arg92Trp/+)and Glialcam^(Lys68Met/Thr132Asn)mouse models were generated based on mutations from patients(c.274C>T(p.Arg92Trp)(c.203A>T(p.Lys68Met),and c.395C>A(p.Thr132Asn))).Brain pathologies of the mouse models at different time points were analyzed.Results Six patients were clinically diagnosed with MLC.Of the six patients,five(Pt1-Pt5)presented with a heterozygous mutation in GLIALCAM(c.274C>T(p.Arg92Trp)or c.275G>C(p.Arg92Pro))and were diagnosed with MLC2B;the remaining patient(Pt6)with two compound heterozygous mutations in GLIALCAM(c.203A>T(p.Lys68Met)and c.395C>A(p.Thr132Asn))was diagnosed with MLC2A.The mutation c.275C>G(p.Arg92Pro)has not been reported before.Clinical manifestations of the patient with MLC2A(Pt6)progressed with regression,whereas the course of the five MLC2B patients remained stable or improved.The Glialcam^(Arg92Trp/+)and Glialcam^(Lys68Met/Thr132Asn)mouse models showed vacuolization in the anterior commissural WM at 1 month of age and vacuolization in the cerebellar WM at 3 and 6 months,respectively.At 9 months,the vacuolization of the GlialcamiLys68Met/Thr132Asn mouse model was heavier than that of the Glialcam^(Arg92Trp/+)mouse model.Decreased expression of Glialcam in Glialcam^(Arg92Trp/+)and Glialcam^(Lys68Met/Thr132Asn)mice may contribute to the vacuolization.Conclusions Clinical and genetic characterization of patients with MLC and GLIALCAM mutations revealed a novel mutation,expanding the spectrum of GLIALCAM mutations.The first Glialcam mouse model with autosomal recessive inheritance and a new Glialcam mouse model with autosomal dominant inheritance were generated.The two mouse models with different modes of inheritance showed different degrees of brain pathological features,which were consistent with the patients'phenotype and further confirmed the pathogenicity of the corresponding mutations.展开更多
Mutations in the leucine-rich repeat kinase 2 gene (LRRK2) are one of the most frequent genetic causes of both familial and sporadic Parkinson’s disease (PD). Mounting evidence has demonstrated pathological similarit...Mutations in the leucine-rich repeat kinase 2 gene (LRRK2) are one of the most frequent genetic causes of both familial and sporadic Parkinson’s disease (PD). Mounting evidence has demonstrated pathological similarities between LRRK2-associated PD (LRRK2-PD) and sporadic PD, suggesting that LRRK2 is a potential disease modulator and a thera-peutic target in PD. LRRK2 mutant knock-in (KI) mouse models display subtle alterations in pathological aspects that mirror early-stage PD, including increased susceptibility of nigrostriatal neurotransmission, development of motor and non-motor symptoms, mitochondrial and autophagy-lysosomal defects and synucleinopathies. This review provides a rationale for the use of LRRK2 KI mice to investigate the LRRK2-mediated pathogenesis of PD and implications from current findings from different LRRK2 KI mouse models, and ultimately discusses the therapeutic potentials against LRRK2-associated pathologies in PD.展开更多
The axolotl is broadly used in regenerative, developmental, and evolutionary biology research. Targeted gene knock-in is crucial for precision transgenesis, enabling disease modeling, visualization, tracking, and func...The axolotl is broadly used in regenerative, developmental, and evolutionary biology research. Targeted gene knock-in is crucial for precision transgenesis, enabling disease modeling, visualization, tracking, and functional manipulation of specific cells or genes of interest(GOIs). Existing CRISPR/Cas9-mediated homology-independent method for gene knock-in often causes “scars/indels” at integration junctions.Here, we develop a CRISPR/Cas9-mediated semi-homology-directed recombination(HDR) knock-in method using a donor construct containing a single homology arm for the precise integration of GOIs.This semi-HDR approach achieves seamless single-end integration of the Cherry reporter gene and a large inducible Cre cassette into intronless genes like Sox2 and Neurod6 in axolotls, which are challenging to modify with the homology-independent method. Additionally, we integrate the inducible Cre cassette into intron-containing loci(e.g., Nkx2.2 and FoxA2) without introducing indels via semi-HDR. GOIs are properly expressed in F0 founders, with approximately 5%-10% showing precise integration confirmed by genotyping. Furthermore, using the Nkx2.2:CreER^(T2)line, we fate-map spinal cord p3 neural progenitor cells,revealing that Nkx2.2^(+) cells adopt different lineages in development and regeneration, preferentially generating motoneurons over oligodendrocytes during regeneration. Overall, this semi-HDR method balances efficiency and precision in the integration of GOIs, providing a valuable tool for generating knock-in axolotls and potentially extending to other species.展开更多
Pigs are an important resource in agriculture and serve as a model for human diseases. Due to their physiological and anatomical similarities with humans, pigs can recapitulate symptoms of human diseases, making them ...Pigs are an important resource in agriculture and serve as a model for human diseases. Due to their physiological and anatomical similarities with humans, pigs can recapitulate symptoms of human diseases, making them a useful model in biomedicine. However, in the past pig models have not been widely used partially because of the difficulty in genetic modification. The lack of true embryonic stem cells in pigs forced researchers to utilize genetic modification in somatic cells and somatic cell nuclear transfer(SCNT) to generate genetically engineered(GE) pigs carrying site-specific modifications. Although possible, this approach is extremely inefficient and GE pigs born through this method often presented developmental defects associated with the cloning process. Advancement in the gene-editing systems such as Zinc-Finger Nucleases(ZFNs), Transcription activator-like effector nucleases(TALENs), and the Clustered regularly interspaced short palindromic repeat(CRISPR)/CRISPR-associated 9(Cas9) system have dramatically increased the efficiency of producing GE pigs. These gene-editing systems, specifically engineered endonucleases, are based on inducing double-stranded breaks(DSBs) at a specific location, and then site-specific modifications can be introduced through one of the two DNA repair pathways: non-homologous end joining(NHEJ) or homology direct repair(HDR).Random insertions or deletions(indels) can be introduced through NHEJ and specific nucleotide sequences can be introduced through HDR, if donor DNA is provided. Use of these engineered endonucleases provides a higher success in genetic modifications, multiallelic modification of the genome, and an opportunity to introduce site-specific modifications during embryogenesis, thus bypassing the need of SCNT in GE pig production. This review will provide a historical prospective of GE pig production and examples of how the gene-editing system, led by engineered endonucleases, have improved GE pig production. We wil also present some of our current progress related to the optimal use of CRISPR/Cas9 system during embryogenesis.展开更多
Genetically engineered mouse(GEM)models are commonly used in biomedical research.Generating GEMs involve complex set of experimental procedures requiring sophisticated equipment and highly skilled technical staff.Beca...Genetically engineered mouse(GEM)models are commonly used in biomedical research.Generating GEMs involve complex set of experimental procedures requiring sophisticated equipment and highly skilled technical staff.Because of these reasons,most research institutes set up centralized core facilities where custom GEMs are created for research groups.Researchers,on the other hand,when they begin thinking about generating GEMs for their research,several questions arise in their minds.For example,what type of model(s)would be best useful for my research,how do I design them,what are the latest technologies and tools available for developing my model(s),and finally how to breed GEMs in my research.As there are several considerations and options in mouse designs,and as it is an expensive and time-consuming endeavor,careful planning upfront can ensure the highest chance of success.In this article,we provide brief answers to several frequently asked questions that arise when researchers begin thinking about generating mouse model(s)for their work.展开更多
Development of the secondary palate displays molecular heterogeneity along the anterior-posterior axis;however, the underlying molecular mechanism remains largely unknown. MSX1 is an anteriorly expressed transcription...Development of the secondary palate displays molecular heterogeneity along the anterior-posterior axis;however, the underlying molecular mechanism remains largely unknown. MSX1 is an anteriorly expressed transcription repressor required for palate development. Here, we investigate the role of Msx1 in regional patterning of the secondary palate. The Wnt1-Cre-mediated expression of Msx1(Rosa Msx1^(Wnt1-Cre))throughout the palatal mesenchyme leads to cleft palate in mice, associated with aberrant cell proliferation and cell death. Osteogenic patterning of the hard palate in Rosa Msx1^(Wnt1-Cre)mice is severely impaired, as revealed by a marked reduction in palatine bone formation and decreased expression of the osteogenic regulator Sp7. Overexpression and knockout of Msx1 in mice show that the transcription repressor promotes the expression of the anterior palate-specific Alx1 but represses the expression of the medialposterior palate genes Barx1, Meox2, and Tbx22. Furthermore, Tbx22 constitutes a direct Msx1 target gene in the secondary palate, suggesting that Msx1 can directly repress the expression of medial-posterior specific genes. Finally, we determine that Sp7 is downstream of Tbx22 in palatal mesenchymal cells,suggesting that a Msx1/Tbx22/Sp7 axis participates in the regulation of palate development. Our findings unveil a novel role for Msx1 in regulating the anterior-posterior growth and patterning of the secondary palate.展开更多
Efficient and stable expression of foreign genes in cells and transgenic animals is important for gain-of-function studies and the establishment of bioreactors.Safe harbor loci in the animal genome enable consistent o...Efficient and stable expression of foreign genes in cells and transgenic animals is important for gain-of-function studies and the establishment of bioreactors.Safe harbor loci in the animal genome enable consistent overexpression of foreign genes,without side effects.However,relatively few safe harbor loci are available in pigs,a fact which has impeded the development of multi-transgenic pig research.We report a strategy for efficient transgene knock-in in the endogenous collagen type I alpha 1 chain(COL1A1)gene using the clustered regularly interspaced short palindromic repeats/CRISPR-associated protein 9(CRISPR/Cas9)system.After the knock-in of a 2A peptide-green fluorescence protein(2A-GFP)transgene in the last codon of COL1A1 in multiple porcine cells,including porcine kidney epithelial(PK15),porcine embryonic fibroblast(PEF)and porcine intestinal epithelial(IPI-2I)cells,quantitative PCR(qPCR),Western blotting,RNA-seq and CCK8 assay were performed to assess the safety of COL1A1 locus.The qPCR results showed that the GFP knock-in had no effect(P=0.29,P=0.66 and P=0.20 for PK15,PEF and IPI-2I cells,respectively)on the mRNA expression of COL1A1 gene.Similarly,no significant differences(P=0.64,P=0.48 and P=0.80 for PK15,PEF and IPI-2I cells,respectively)were found between the GFP knock-in and wild type cells by Western blotting.RNA-seq results revealed that the transcriptome of GFP knock-in PEF cells had a significant positive correlation(P<2.2e–16)with that of the wild type cells,indicating that the GFP knock-in did not alter the global expression of endogenous genes.Furthermore,the CCK8 assay showed that the GFP knock-in events had no adverse effects(P_(24)h=0.31,P_(48)h=0.96,P_(72)h=0.24,P_(96)h=0.17,and P_(120)h=0.38)on cell proliferation of PK15 cells.These results indicate that the COL1A1 locus can be used as a safe harbor for foreign genes knock-in into the pig genome and can be broadly applied to farm animal breeding and biomedical model establishment.展开更多
Estrogen has various physiological functions and the estrogen receptor (ER) is a key regulator of those functions. ERα is a ligand-dependent transcription factor and that activity is mediated by the transactivating f...Estrogen has various physiological functions and the estrogen receptor (ER) is a key regulator of those functions. ERα is a ligand-dependent transcription factor and that activity is mediated by the transactivating function-1 (AF-1) in the N-terminal domain and transactivating function-2 (AF-2) in the C-terminal ligand-binding domain. The functions of ERα AF-1 and AF-2 have been characterized by various in vitro experiments, however, there is still less information about the in vivo physiological functions of ERα AF-1 and AF-2. Recently, we established a genetically mutated ERα AF-2 knock-in mouse (AF2ERKI) that possessed L543A, L544A mutated-ERα. This AF-2 core mutation disrupted AF-2 function and resulted in ERα null phenotypes. This mouse model revealed that proper AF-2 core structure and function were indispensable for ERα-mediated physiological responses and AF-1 functionality. AF2ER mutation reverses the ERα antagonists to agonists and that activity is mediated by AF-1 solely. The pure antagonist, ICI182780/fulvestrant, activated several estrogen-mediated physiological responses in the AF2ERKI mouse. The AF2ERKI mouse model will be useful to discern estrogen physiological functions which involve AF-1.展开更多
Histone modification including H3 lysine 79 methylation (H3K79me) plays a key role during gene transcription and DNA damage repair. DOT1L, the sole methyltransferase for three states of H3K79me, is implicated in leuke...Histone modification including H3 lysine 79 methylation (H3K79me) plays a key role during gene transcription and DNA damage repair. DOT1L, the sole methyltransferase for three states of H3K79me, is implicated in leukemia, colorectal cancer, and dilated cardiomyopathy. However, understanding of DOT1L and H3K79me in these pathways and disease pathogenesis has been limited due to the difficulty of working with DOT1L protein. For instance, locus-specific or genome-wide binding sites of DOT1L revealed by chromatin immunoprecipitation (ChIP)-based methods are necessary for inferring its functions, but high-quality ChIP-grade antibodies are currently not available. Herein we have developed a knock-in approach to tag endogenous DOT1L with 3 × Flag at its C-terminal domain to follow functional analyses. The knock-in was facilitated by using TALENs to induce a targeted double-strand break at the endogenous DOTIL to stimulate local homologous recombination at that site. The single cell colonies with successful knock-in were isolated and verified by different methods. We also demonstrated that tagged DOT1L maintains its normal function in terms of methylation and that the engineered cells would be very useful for further studies.展开更多
Plant diseases,caused by a wide range of pathogens,severely reduce crop yield and quality,posing a significant threat to global food security.Developing broad-spectrum resistance(BSR)in crops is a key strategy for con...Plant diseases,caused by a wide range of pathogens,severely reduce crop yield and quality,posing a significant threat to global food security.Developing broad-spectrum resistance(BSR)in crops is a key strategy for controlling crop diseases and ensuring sustainable crop production.Cloning disease-resistance(R)genes and understanding their underlying molecular mechanisms provide new genetic resources and strategies for crop breeding.Novel genetic engineering and genome editing tools have accelerated the study and engineering of BSR genes in crops,which is the primary focus of this review.We first summarize recent advances in understanding the plant immune system,followed by an examination of the molecular mechanisms underlying BSR in crops.Finally,we highlight diverse strategies employed to achieve BSR,including gene stacking to combine multiple R genes,multiplexed genome editing of susceptibility genes and promoter regions of executor R genes,editing cis-regulatory elements to fine-tune gene expression,RNA interference,saturation mutagenesis,and precise genomic insertions.The genetic studies and engineering of BSR are accelerating the breeding of disease-resistant cultivars,contributing to crop improvement and enhancing global food security.展开更多
Arrhythmogenic right ventricular dysplasia/cardiomyopathy(ARVD/C)is a genetic cardiac muscle disease that accounts for approximately 30%sudden cardiac death in young adults.The Ser358Leu mutation of transmembrane prot...Arrhythmogenic right ventricular dysplasia/cardiomyopathy(ARVD/C)is a genetic cardiac muscle disease that accounts for approximately 30%sudden cardiac death in young adults.The Ser358Leu mutation of transmembrane protein 43(TMEM43)was commonly identified in the patients of highly lethal and fully penetrant ARVD subtype,ARVD5.Here,we generated TMEM43 S358L mouse to explore the underlying mechanism.This mouse strain showed the classic patholo.gies of ARVD patients,including structural abnormalities and cardiac fibrofatty.TMEM43 S358L mutation led to hyper-activated nuclear factor kB(NFkB)activation in heart tissues and primary cardiomy.ocyte cells.Importantly,this hyper activation of NF-κB directly drove the expression of pro-fibrotic gene,transforming growth factor beta(TGFβ),and enhanced downstream signal,indicating that TMEM43 S358L mutation up-regulates NF-κB-TGFβ signal cascade during ARVD cardiac fibrosis.Our study partially reveals the regulatory mechanism of ARVD development.展开更多
A series of clustered regularly interspaced short palindromic repeats(CRISPR)-CRISPR associated protein 9(Cas9)systems have been engineered for genome editing.The most widely used Cas9 is SpCas9 from Streptococcus pyo...A series of clustered regularly interspaced short palindromic repeats(CRISPR)-CRISPR associated protein 9(Cas9)systems have been engineered for genome editing.The most widely used Cas9 is SpCas9 from Streptococcus pyogenes and SaCas9 from Staphylococcus aureus.However,a comparison of their detailed gene editing outcomes is still lacking.By characterizing the editing outcomes of 11 sites in human induced pluripotent stem cells(iPSCs)and K562 cells,we found that SaCas9 could edit the genome with greater efficiencies than SpCas9.We also compared the effects of spacer lengths of single-guide RNAs(sgRNAs;18–21 nt for SpCas9 and 19–23 nt for SaCas9)and found that the optimal spacer lengths were 20 nt and 21 nt for SpCas9 and SaCas9,respectively.However,the optimal spacer length for a particular sgRNA was 18–21 nt for SpCas9 and 21–22 nt for SaCas9.Furthermore,SpCas9 exhibited a more substantial bias than SaCas9 for nonhomologous end-joining(NHEJ)+1 insertion at the fourth nucleotide upstream of the protospacer adjacent motif(PAM),indicating a characteristic of a staggered cut.Accordingly,editing with SaCas9 led to higher efficiencies of NHEJ-mediated double-stranded oligodeoxynucleotide(dsODN)insertion or homology-directed repair(HDR)-mediated adeno-associated virus serotype 6(AAV6)donor knock-in.Finally,GUIDE-seq analysis revealed that SaCas9 exhibited significantly reduced off-target effects compared with SpCas9.Our work indicates the superior performance of SaCas9 to SpCas9 in transgene integration-based therapeutic gene editing and the necessity to identify the optimal spacer length to achieve desired editing results.展开更多
With their capability to undergo unlimited self-renewal and to differentiate into all cell types in the body, human embryonic stem cells （hESCs） hold great promise in human cell therapy. However, there are limited t...With their capability to undergo unlimited self-renewal and to differentiate into all cell types in the body, human embryonic stem cells （hESCs） hold great promise in human cell therapy. However, there are limited tools for easily identifying and isolating live hESC-derived cells. To track hESC-derived neural progenitor cells （NPCs）, we applied homologous recombination to knock-in the mCherry gene into the Nestin locus of hESCs. This facilitated the genetic labeling of Nestin positive neural progenitor cells with mCherry. Our reporter system enables the visualization of neural induction from hESCs both in vitro （embryoid bodies） and in vivo （ter- atomas）. This system also permits the identification of different neural subpopulations based on the intensity of our fluorescent reporter. In this context, a high level of mCherry expression showed enrichment for neural progenitors, while lower mCherry corresponded with more committed neural states. Combination of mCherry high expression with cell surface antigen staining enabled further enrichment of hESC-derived NPCs. These mCherry＊ NPCs could be expanded in culture and their differentiation resulted in a down-regulation of mCherry consistent with the loss of Nestin expression. Therefore, we have developed a fluorescent reporter system that can be used to trace neural differentiation events of hESCs.展开更多
Excessive cholesterol absorption from intestinal lumen contributes to the pathogenesis of hypercholesterolemia,which is an independent risk factor for atherosclerotic cardiovascular disease.Niemann-Pick C1-like 1(NPC1...Excessive cholesterol absorption from intestinal lumen contributes to the pathogenesis of hypercholesterolemia,which is an independent risk factor for atherosclerotic cardiovascular disease.Niemann-Pick C1-like 1(NPC1L1)is a major membrane protein responsible for cholesterol absorption,in which the physiological role of vesicular endocytosis is still controversial,and it lacks a feasible tool to visualize and evaluate the endocytosis of NPC1L1 vesicles in vivo.Here,we genetically labeled endogenous NPC1L1 protein with EGFP in a knock-in mouse model,and demonstrated fluorescent visualization and evaluation of the endocytic vesicles of NPC1L1-cago during intestinal cholesterol absorption.The homozygous NPC1L1-EGFP mice have normal NPC1L1 expression pattern as well as cholesterol homeostasis on chow or high-cholesterol diets.The fluorescence of NPC1L1-EGFP fusion protein localizes at the brush border membrane of small intestine,and EGFP-positive vesicles is visualized beneath the membrane as early as 5 min post oral gavage of cholesterol.Of note,the vesicles colocalize with the early endosomal marker early endosome antigen 1(EEA1)and the filipin-stained free cholesterol.Pretreatment with NPC1L1 inhibitor ezetimibe inhibits the formation of these cholesterol-induced endocytic vesicles.Our data support the notion that NPC1L1-mediated cholesterol absorption is a vesicular endocytic process.NPC1L1-EGFP mice are a useful model for visualizing cellular NPC1L1-cargo vesicle itineraries and for evaluating NPC1L1 activity in vivo in response to diverse pharmacological agents and nutrients.展开更多
基金supported by the National Transgenic Project of China (2016ZX08010001-002)the National Natural Science Foundation of China (81471001)+1 种基金the Inner Mongolia Science and Technology Program, China (201502073)the National 863 Prgram of China (2009AA10Z111)
文摘This study aimed to compare the efficiencies of clustered regulatory interspaced short palindromic repeat（CRISPR）/Cas9-mediated gene knock-ins with zinc finger nucleases（ZFNs） and transcription activator-like effector nucleases（TALENs） in bovine and dairy goat fetal fibroblasts. To test the knock-in efficiency, a set of ZFNs and CRISPR/Cas9 plasmids were designed to edit the bovine myostatin（MSTN） gene at exon 2, while a set of TALENs and CRISPR/Cas9 plasmids were designed for editing the dairy goat β-casein gene at exon 2. Donor plasmids utilizing the ZFNs, TALENs, and CRISPR/Cas9 cutting sites were constructed in theGFP-PGK-Neo R plasmid background, including a 5′ and 3′ homologous arm flanking the genes humanized Fat-1（h Fat-1） or enhanced green fluorescent protein（eGFP）. Subsequently, the ZFNs, TALENs, or CRISPR/Cas9 and thehFat-1 or eGFP plasmids were co-transfected by electroporation into bovine and dairy goat fetal fibroblasts. After G418（Geneticin） selection, single cells were obtained by mouth pipetting, flow cytometry or a cell shove. The gene knock-in events were screened by PCR across the homologous arms. The results showed that in bovine fetal fibrobalsts, the efficiencies of ZFNs-mediated eGFP andhFat-1 gene knock-ins were 13.68 and 0%, respectively. The efficiencies of CRISPR/Cas9-mediated eGFP andhFat-1 gene knock-ins were 77.02 and 79.01%, respectively. The eGFP gene knock-in efficiency using CRISPR/Cas9 was about 5.6 times higher than when using the ZFNs gene editing system. Additionally, thehFat-1 gene knock-in was only obtained when using the CRISPR/Cas9 system. The difference of knockin efficiencies between the ZFNs and CRISPR/Cas9 systems were extremely significant（P〈0.01）. In the dairy goat fetal fibroblasts, the efficiencies of TALENs-mediated eGFP andhFat-1 gene knock-ins were 32.35 and 26.47%, respectively. Theefficiencies of eGFP and hFat-1 gene knock-ins using CRISPR/Cas9 were 70.37 and 74.29%, respectively. The knock-in efficiencies difference between the TALENs and CRISPR/Cas9 systems were extremely significant（P〈0.01）. This study demonstrated that CRISPR/Cas9 was more efficient at gene knock-ins in domesticated animal cells than ZFNs and TALENs. The CRISPR/Cas9 technology offers a new era of precise gene editing in domesticated animal cell lines.
基金supported by the National Natural Science Foundation of China(32172503 and 32260721)the Natural Science Foundation of Fujian Province,China(2023J01069)+2 种基金the State Key Laboratory of Ecological Pest Control for Fujian and Taiwan Crops,China(SKL2022001)the Innovation Fund of Fujan Agriculture and Forestry University,China(KFB23014A)the Undergraduate Training Program for Innovation and Entrepreneurship of Fujian Province,China(S202210389101).
文摘Genetic pest control strategies based on precise sex separation and only releasing sterile males can be accomplished by site-specific genome editing.In the current study,we showed that the mutation of single-allele Pxfl(2)d can significantly impair the normal mating behavior and testis development in male adults of the notorious cruciferous insect pest Plutella xylostella,in addition to its known functions in the ovarian development in female adults and egg hatching.Subsequent CRISPR/Cas9-based knock-in experiments revealed that site-specific integration of an exogenous green fluorescent protein(GFP)gene into autosomal Pxfl(2)d for labelling mutants could be achieved.However,this gene is not a suitable target for GFP insertion to establish a genetically stable knock-in strain because of the severe decline in reproductive capacity.We further screened for the W-chromosome-linked and Z-chromosome-linked regions to test the knock-in efficiency mediated by CRISPR/Cas9.The results verified that both types of chromosomes can be targeted for the site-specific insertion of exogenous sequences.We ultimately obtained a homozygous knock-in strain with the integration of both Cas9 and cyan fluorescent protein(CFP)expression cassettes on a Z-linked region in P.xylostella,which can also be used for early sex detection.By injecting the sgRNA targeting Pxfl(2)d alone into the eggs laid by female adults of the Z-Cas9-CFP strain,the gene editing efficiency reached 29.73%,confirming the success of expressing a functional Cas9 gene.Taken together,we demonstrated the feasibility of the knock-in of an exogenous gene to different genomic regions in P.xylostella,while the establishment of a heritable strain required the positioning of appropriate sites.This study provides an important working basis and technical support for further developing genetic strategies for insect pest control.
文摘Huntington＇s disease （HD） is an inherited autosomal dominant neurodegenerative disease characterized by pro- gressive motor deficits, cognitive decline, and psychiatric symptoms. It is caused by a pathological expansion of CAG trinucleotide repeats in exon 1 of the HD gene, resulting in the translation of a mutant form of huntingtin protein （mutant Htt） with an expanded polyglutamine domain in the N-terminal region [1 ]. Despite great progress in understanding the pathogenesis of HD using multiple mouse models, the exact mechanisms by which mutant Htt induces neuronal dysfunction and death are still not completely clear, and there is no curative treatment for this disease. An important reason is that the mouse, which is the most widely used animal model in HD research, differs from the human in many aspects, including the physiology, drug metabolism, blood-brain barrier, life span, brain volume, and neuroanatomical organization [2]. Thus, it is necessary to establish HD models with higher species than rodents, such as the dog, pig, and non- human primate, so as to bridge the gap between preclinical mouse models and clinical studies.
基金the National Key Research and Development Program of China(2017YFA0105103,2021YFA0805903)the National Natural Science Foundation of China(81941004,32170542)+10 种基金2020 Research Program of Sanya Yazhou Bay Science and Technology City(202002011)Major Science and Technology Projects of Hainan Province(ZDKJ2021030)Key Research&Development Program of Hainan Province(ZDYF2021SHFZ052)Youth Innovation Promotion Association of the Chinese Academy of Sciences(2019347)Young Elite Scientist Sponsorship Program by CAST(YESS20200024)Biological Resources Progaramme,Chinese Academy of Sciences(KFJBRP-017-57)Key Research&Development Program of Bioland Laboratory(Guangzhou Regenerative Medicine and Health Guangdong Laboratory)(2018GZR110104004)China Postdoctoral Science Foundation(2020M682943)Science and Technology Planning Project of Guangdong Province,China(2019A030317010,2020B1212060052,2021B1212040016,2021A1515011110)Science and Technology Program of Guangzhou,China(202007030003)Research Unit of Generation of Large Animal Disease Models,Chinese Academy of Medical Sciences(2019-I2M-5-025)。
文摘Inducible expression systems are indispensable for precise regulation and in-depth analysis of biological process.Binary Tet-On system has been widely employed to regulate transgenic expression by doxycycline.Previous pig models with tetracycline regulatory elements were generated through random integration.This process often resulted in uncertain expression and unpredictable phenotypes,thus hindering their applications.Here,by precise knock-in of binary Tet-On 3G elements into Rosa26 and Hipp11 locus,respectively,a double knock-in reporter pig model was generated.We characterized excellent properties of this system for controllable transgenic expression both in vitro and in vivo.Two att P sites were arranged to flank the td Tomato to switch reporter gene.Single or multiple gene replacement was efficiently and faithfully achieved in fetal fibroblasts and nuclear transfer embryos.To display the flexible application of this system,we generated a pig strain with Dox-inducing h KRASexpression through phiC31 integrase-mediated cassette exchange.After eight months of Dox administration,squamous cell carcinoma developed in the nose,mouth,and scrotum,which indicated this pig strain could serve as an ideal large animal model to study tumorigenesis.Overall,the established pig models with controllable and switchable transgene expression system will provide a facilitating platform for transgenic and biomedical research.
基金funded by the National Natural Science Foundation of China(Grant Number:81741053,81501123)the Beijing Natural Science Foundation(Grant Number:7151010,7172217)+5 种基金the Bejing Municipal Science&Technology Commission(Grant Number:Z161100000216133,Z161100004916169)the Beijing Institute for Brain Disorders Foundation(Grant Number:BIBDPXM2014_014226_000016)the Beijing Municipal Natural Science Key Project(Grant Number 15G10050)Bejing key laboratory of molecular diagnosis and study on pediatric genetic discases(Grant Number BZ0317)the National Key Rescarch and Development Program of China(Grant Number:2016YFC1306201,2016YFC0901505)the Fundamental Research Funds for the Central Universities(Grant Number:BMU2017JI002).
文摘Background Megalencephalic leukoencephalopathy with subcortical cysts(MLC)is a rare neurological degenerative disorder caused by the mutations of MLC1 or GLIALCAM with autosomal recessive or autosomal dominant inheritance and a different prognosis,characterized by macrocephaly,delayed motor and cognitive development,and bilateral abnormal signals in cerebral white matter(WM)with or without cysts on magnetic resonance imaging(MRI).This study aimed to reveal the clinical and genetic features of MLC patients with GLIALCAM mutations and to explore the brain pathological characteristics and prognosis of mouse models with different modes of inheritance.Methods Clinical information and peripheral venous blood were collected from six families.Genetic analysis was performed by Sanger sequencing of GLIALCAM.Glialcam^(Arg92Trp/+)and Glialcam^(Lys68Met/Thr132Asn)mouse models were generated based on mutations from patients(c.274C>T(p.Arg92Trp)(c.203A>T(p.Lys68Met),and c.395C>A(p.Thr132Asn))).Brain pathologies of the mouse models at different time points were analyzed.Results Six patients were clinically diagnosed with MLC.Of the six patients,five(Pt1-Pt5)presented with a heterozygous mutation in GLIALCAM(c.274C>T(p.Arg92Trp)or c.275G>C(p.Arg92Pro))and were diagnosed with MLC2B;the remaining patient(Pt6)with two compound heterozygous mutations in GLIALCAM(c.203A>T(p.Lys68Met)and c.395C>A(p.Thr132Asn))was diagnosed with MLC2A.The mutation c.275C>G(p.Arg92Pro)has not been reported before.Clinical manifestations of the patient with MLC2A(Pt6)progressed with regression,whereas the course of the five MLC2B patients remained stable or improved.The Glialcam^(Arg92Trp/+)and Glialcam^(Lys68Met/Thr132Asn)mouse models showed vacuolization in the anterior commissural WM at 1 month of age and vacuolization in the cerebellar WM at 3 and 6 months,respectively.At 9 months,the vacuolization of the GlialcamiLys68Met/Thr132Asn mouse model was heavier than that of the Glialcam^(Arg92Trp/+)mouse model.Decreased expression of Glialcam in Glialcam^(Arg92Trp/+)and Glialcam^(Lys68Met/Thr132Asn)mice may contribute to the vacuolization.Conclusions Clinical and genetic characterization of patients with MLC and GLIALCAM mutations revealed a novel mutation,expanding the spectrum of GLIALCAM mutations.The first Glialcam mouse model with autosomal recessive inheritance and a new Glialcam mouse model with autosomal dominant inheritance were generated.The two mouse models with different modes of inheritance showed different degrees of brain pathological features,which were consistent with the patients'phenotype and further confirmed the pathogenicity of the corresponding mutations.
基金Tai Hung Fai Charitable Foundation-Edwin S H Leong Research Programme for Parkinson’s DiseaseThe Henry G.Leong Endowed Professorship in Neurology+1 种基金The Donation Fund for Neurology ResearchHealth and Medical Research Fund(HMRF),Food and Health Bureau,Hong Kong S.A.R.
文摘Mutations in the leucine-rich repeat kinase 2 gene (LRRK2) are one of the most frequent genetic causes of both familial and sporadic Parkinson’s disease (PD). Mounting evidence has demonstrated pathological similarities between LRRK2-associated PD (LRRK2-PD) and sporadic PD, suggesting that LRRK2 is a potential disease modulator and a thera-peutic target in PD. LRRK2 mutant knock-in (KI) mouse models display subtle alterations in pathological aspects that mirror early-stage PD, including increased susceptibility of nigrostriatal neurotransmission, development of motor and non-motor symptoms, mitochondrial and autophagy-lysosomal defects and synucleinopathies. This review provides a rationale for the use of LRRK2 KI mice to investigate the LRRK2-mediated pathogenesis of PD and implications from current findings from different LRRK2 KI mouse models, and ultimately discusses the therapeutic potentials against LRRK2-associated pathologies in PD.
基金supported by the National Key R&D Program of China(2021YFA0805000,2023YFA1800600,2019YFE0106700)the National Natural Science Foundation of China(92268114,31970782,32070819)+1 种基金the High-level Hospital Construction Project of GuangdongProvincial People'sHospital(DFJHBF202103 and KJ012021012)BGI grant(BGIRSZ20210002).
文摘The axolotl is broadly used in regenerative, developmental, and evolutionary biology research. Targeted gene knock-in is crucial for precision transgenesis, enabling disease modeling, visualization, tracking, and functional manipulation of specific cells or genes of interest(GOIs). Existing CRISPR/Cas9-mediated homology-independent method for gene knock-in often causes “scars/indels” at integration junctions.Here, we develop a CRISPR/Cas9-mediated semi-homology-directed recombination(HDR) knock-in method using a donor construct containing a single homology arm for the precise integration of GOIs.This semi-HDR approach achieves seamless single-end integration of the Cherry reporter gene and a large inducible Cre cassette into intronless genes like Sox2 and Neurod6 in axolotls, which are challenging to modify with the homology-independent method. Additionally, we integrate the inducible Cre cassette into intron-containing loci(e.g., Nkx2.2 and FoxA2) without introducing indels via semi-HDR. GOIs are properly expressed in F0 founders, with approximately 5%-10% showing precise integration confirmed by genotyping. Furthermore, using the Nkx2.2:CreER^(T2)line, we fate-map spinal cord p3 neural progenitor cells,revealing that Nkx2.2^(+) cells adopt different lineages in development and regeneration, preferentially generating motoneurons over oligodendrocytes during regeneration. Overall, this semi-HDR method balances efficiency and precision in the integration of GOIs, providing a valuable tool for generating knock-in axolotls and potentially extending to other species.
基金the National Institutes of Health R21OD019934(KL)and U42OD011140(RSP)
文摘Pigs are an important resource in agriculture and serve as a model for human diseases. Due to their physiological and anatomical similarities with humans, pigs can recapitulate symptoms of human diseases, making them a useful model in biomedicine. However, in the past pig models have not been widely used partially because of the difficulty in genetic modification. The lack of true embryonic stem cells in pigs forced researchers to utilize genetic modification in somatic cells and somatic cell nuclear transfer(SCNT) to generate genetically engineered(GE) pigs carrying site-specific modifications. Although possible, this approach is extremely inefficient and GE pigs born through this method often presented developmental defects associated with the cloning process. Advancement in the gene-editing systems such as Zinc-Finger Nucleases(ZFNs), Transcription activator-like effector nucleases(TALENs), and the Clustered regularly interspaced short palindromic repeat(CRISPR)/CRISPR-associated 9(Cas9) system have dramatically increased the efficiency of producing GE pigs. These gene-editing systems, specifically engineered endonucleases, are based on inducing double-stranded breaks(DSBs) at a specific location, and then site-specific modifications can be introduced through one of the two DNA repair pathways: non-homologous end joining(NHEJ) or homology direct repair(HDR).Random insertions or deletions(indels) can be introduced through NHEJ and specific nucleotide sequences can be introduced through HDR, if donor DNA is provided. Use of these engineered endonucleases provides a higher success in genetic modifications, multiallelic modification of the genome, and an opportunity to introduce site-specific modifications during embryogenesis, thus bypassing the need of SCNT in GE pig production. This review will provide a historical prospective of GE pig production and examples of how the gene-editing system, led by engineered endonucleases, have improved GE pig production. We wil also present some of our current progress related to the optimal use of CRISPR/Cas9 system during embryogenesis.
基金We thank D.D.Meigs(University of Nebraska Medical Center)and Tonya Cejka(freelance English editor)for editing assistance.C.B.G.is funded by NIH grants R35HG010719,R21GM129559,R21AI143394 and R21DA046831.M.O.is funded by 2016–2017 Tokai University School of Medicine Project Research,the Research Aid from the Institute of Medical Sciences in Tokai University,Grant-in-Aid for Scientific Research(25290035)from MEXTa Grant-in-Aid for Challenging Exploratory Research(15K14371)from JSPS.
文摘Genetically engineered mouse(GEM)models are commonly used in biomedical research.Generating GEMs involve complex set of experimental procedures requiring sophisticated equipment and highly skilled technical staff.Because of these reasons,most research institutes set up centralized core facilities where custom GEMs are created for research groups.Researchers,on the other hand,when they begin thinking about generating GEMs for their research,several questions arise in their minds.For example,what type of model(s)would be best useful for my research,how do I design them,what are the latest technologies and tools available for developing my model(s),and finally how to breed GEMs in my research.As there are several considerations and options in mouse designs,and as it is an expensive and time-consuming endeavor,careful planning upfront can ensure the highest chance of success.In this article,we provide brief answers to several frequently asked questions that arise when researchers begin thinking about generating mouse model(s)for their work.
基金supported by grants from the National Natural Scientific Foundation of China (81771028 and 317771593)Medical Health Science and Technology Project of Zhejiang (2021KY891)Medical Health Science and Technology Major Project of Hangzhou (Z20200046)。
文摘Development of the secondary palate displays molecular heterogeneity along the anterior-posterior axis;however, the underlying molecular mechanism remains largely unknown. MSX1 is an anteriorly expressed transcription repressor required for palate development. Here, we investigate the role of Msx1 in regional patterning of the secondary palate. The Wnt1-Cre-mediated expression of Msx1(Rosa Msx1^(Wnt1-Cre))throughout the palatal mesenchyme leads to cleft palate in mice, associated with aberrant cell proliferation and cell death. Osteogenic patterning of the hard palate in Rosa Msx1^(Wnt1-Cre)mice is severely impaired, as revealed by a marked reduction in palatine bone formation and decreased expression of the osteogenic regulator Sp7. Overexpression and knockout of Msx1 in mice show that the transcription repressor promotes the expression of the anterior palate-specific Alx1 but represses the expression of the medialposterior palate genes Barx1, Meox2, and Tbx22. Furthermore, Tbx22 constitutes a direct Msx1 target gene in the secondary palate, suggesting that Msx1 can directly repress the expression of medial-posterior specific genes. Finally, we determine that Sp7 is downstream of Tbx22 in palatal mesenchymal cells,suggesting that a Msx1/Tbx22/Sp7 axis participates in the regulation of palate development. Our findings unveil a novel role for Msx1 in regulating the anterior-posterior growth and patterning of the secondary palate.
基金supported by the Major Scientific Research Tasks for Scientific and Technological Innovation Projects of the Chinese Academy of Agricultural Sciences(CAAS-ZDRW202006)the National Transgenic Breeding Project(2018ZX08010-10B)the Agricultural Science and Technology Innovation Program of Chinese Academy of Agricultural Sciences(ASTIP-IAS05).
文摘Efficient and stable expression of foreign genes in cells and transgenic animals is important for gain-of-function studies and the establishment of bioreactors.Safe harbor loci in the animal genome enable consistent overexpression of foreign genes,without side effects.However,relatively few safe harbor loci are available in pigs,a fact which has impeded the development of multi-transgenic pig research.We report a strategy for efficient transgene knock-in in the endogenous collagen type I alpha 1 chain(COL1A1)gene using the clustered regularly interspaced short palindromic repeats/CRISPR-associated protein 9(CRISPR/Cas9)system.After the knock-in of a 2A peptide-green fluorescence protein(2A-GFP)transgene in the last codon of COL1A1 in multiple porcine cells,including porcine kidney epithelial(PK15),porcine embryonic fibroblast(PEF)and porcine intestinal epithelial(IPI-2I)cells,quantitative PCR(qPCR),Western blotting,RNA-seq and CCK8 assay were performed to assess the safety of COL1A1 locus.The qPCR results showed that the GFP knock-in had no effect(P=0.29,P=0.66 and P=0.20 for PK15,PEF and IPI-2I cells,respectively)on the mRNA expression of COL1A1 gene.Similarly,no significant differences(P=0.64,P=0.48 and P=0.80 for PK15,PEF and IPI-2I cells,respectively)were found between the GFP knock-in and wild type cells by Western blotting.RNA-seq results revealed that the transcriptome of GFP knock-in PEF cells had a significant positive correlation(P<2.2e–16)with that of the wild type cells,indicating that the GFP knock-in did not alter the global expression of endogenous genes.Furthermore,the CCK8 assay showed that the GFP knock-in events had no adverse effects(P_(24)h=0.31,P_(48)h=0.96,P_(72)h=0.24,P_(96)h=0.17,and P_(120)h=0.38)on cell proliferation of PK15 cells.These results indicate that the COL1A1 locus can be used as a safe harbor for foreign genes knock-in into the pig genome and can be broadly applied to farm animal breeding and biomedical model establishment.
文摘Estrogen has various physiological functions and the estrogen receptor (ER) is a key regulator of those functions. ERα is a ligand-dependent transcription factor and that activity is mediated by the transactivating function-1 (AF-1) in the N-terminal domain and transactivating function-2 (AF-2) in the C-terminal ligand-binding domain. The functions of ERα AF-1 and AF-2 have been characterized by various in vitro experiments, however, there is still less information about the in vivo physiological functions of ERα AF-1 and AF-2. Recently, we established a genetically mutated ERα AF-2 knock-in mouse (AF2ERKI) that possessed L543A, L544A mutated-ERα. This AF-2 core mutation disrupted AF-2 function and resulted in ERα null phenotypes. This mouse model revealed that proper AF-2 core structure and function were indispensable for ERα-mediated physiological responses and AF-1 functionality. AF2ER mutation reverses the ERα antagonists to agonists and that activity is mediated by AF-1 solely. The pure antagonist, ICI182780/fulvestrant, activated several estrogen-mediated physiological responses in the AF2ERKI mouse. The AF2ERKI mouse model will be useful to discern estrogen physiological functions which involve AF-1.
文摘Histone modification including H3 lysine 79 methylation (H3K79me) plays a key role during gene transcription and DNA damage repair. DOT1L, the sole methyltransferase for three states of H3K79me, is implicated in leukemia, colorectal cancer, and dilated cardiomyopathy. However, understanding of DOT1L and H3K79me in these pathways and disease pathogenesis has been limited due to the difficulty of working with DOT1L protein. For instance, locus-specific or genome-wide binding sites of DOT1L revealed by chromatin immunoprecipitation (ChIP)-based methods are necessary for inferring its functions, but high-quality ChIP-grade antibodies are currently not available. Herein we have developed a knock-in approach to tag endogenous DOT1L with 3 × Flag at its C-terminal domain to follow functional analyses. The knock-in was facilitated by using TALENs to induce a targeted double-strand break at the endogenous DOTIL to stimulate local homologous recombination at that site. The single cell colonies with successful knock-in were isolated and verified by different methods. We also demonstrated that tagged DOT1L maintains its normal function in terms of methylation and that the engineered cells would be very useful for further studies.
基金supported by Biological Breeding-National Science and Technology Major Projects(2023ZD04070)the Key R&D Program of Hubei Province(2023BBB171)+3 种基金the National Key R&D Program of China(2022YFA1304402)Fundamental Research Funds for the Central Universities(2662023PY006,AML2023A05,2662024ZKPY001)(to G.L.)supported by the Fundamental Research Funds for the Central Universities(2662023PY006)(to K.X.)supported by the National Natural Science Foundation of China(32172373 and 32293243)(to G.L.and K.X.,respectively)and Hubei Hongshan Laboratory.
文摘Plant diseases,caused by a wide range of pathogens,severely reduce crop yield and quality,posing a significant threat to global food security.Developing broad-spectrum resistance(BSR)in crops is a key strategy for controlling crop diseases and ensuring sustainable crop production.Cloning disease-resistance(R)genes and understanding their underlying molecular mechanisms provide new genetic resources and strategies for crop breeding.Novel genetic engineering and genome editing tools have accelerated the study and engineering of BSR genes in crops,which is the primary focus of this review.We first summarize recent advances in understanding the plant immune system,followed by an examination of the molecular mechanisms underlying BSR in crops.Finally,we highlight diverse strategies employed to achieve BSR,including gene stacking to combine multiple R genes,multiplexed genome editing of susceptibility genes and promoter regions of executor R genes,editing cis-regulatory elements to fine-tune gene expression,RNA interference,saturation mutagenesis,and precise genomic insertions.The genetic studies and engineering of BSR are accelerating the breeding of disease-resistant cultivars,contributing to crop improvement and enhancing global food security.
基金grants from National Natural Science Foundation of China(81570211 to X.Lin)China Postdoctoral Science Foundation(023221010 to G.Zheng).
文摘Arrhythmogenic right ventricular dysplasia/cardiomyopathy(ARVD/C)is a genetic cardiac muscle disease that accounts for approximately 30%sudden cardiac death in young adults.The Ser358Leu mutation of transmembrane protein 43(TMEM43)was commonly identified in the patients of highly lethal and fully penetrant ARVD subtype,ARVD5.Here,we generated TMEM43 S358L mouse to explore the underlying mechanism.This mouse strain showed the classic patholo.gies of ARVD patients,including structural abnormalities and cardiac fibrofatty.TMEM43 S358L mutation led to hyper-activated nuclear factor kB(NFkB)activation in heart tissues and primary cardiomy.ocyte cells.Importantly,this hyper activation of NF-κB directly drove the expression of pro-fibrotic gene,transforming growth factor beta(TGFβ),and enhanced downstream signal,indicating that TMEM43 S358L mutation up-regulates NF-κB-TGFβ signal cascade during ARVD cardiac fibrosis.Our study partially reveals the regulatory mechanism of ARVD development.
基金supported by the National Natural Science Foundation of China(Grant Nos.82070115,81770198,81870149,81970121,and 8142100)the National Key R&D Program of China(Grant Nos.2019YFA0110803,2019YFA0110802,2019YFA0110204,and 2016YFA0100600)+1 种基金the Tianjin Municipal Science and Technology Commission Grant(Grant No.19JCZDJC33000)the CAMS Innovation Fund for Medical Sciences(Grant Nos.2017-I2M-2-001,2017-I2M-B&R-04,and 2019-I2M-1-006).
文摘A series of clustered regularly interspaced short palindromic repeats(CRISPR)-CRISPR associated protein 9(Cas9)systems have been engineered for genome editing.The most widely used Cas9 is SpCas9 from Streptococcus pyogenes and SaCas9 from Staphylococcus aureus.However,a comparison of their detailed gene editing outcomes is still lacking.By characterizing the editing outcomes of 11 sites in human induced pluripotent stem cells(iPSCs)and K562 cells,we found that SaCas9 could edit the genome with greater efficiencies than SpCas9.We also compared the effects of spacer lengths of single-guide RNAs(sgRNAs;18–21 nt for SpCas9 and 19–23 nt for SaCas9)and found that the optimal spacer lengths were 20 nt and 21 nt for SpCas9 and SaCas9,respectively.However,the optimal spacer length for a particular sgRNA was 18–21 nt for SpCas9 and 21–22 nt for SaCas9.Furthermore,SpCas9 exhibited a more substantial bias than SaCas9 for nonhomologous end-joining(NHEJ)+1 insertion at the fourth nucleotide upstream of the protospacer adjacent motif(PAM),indicating a characteristic of a staggered cut.Accordingly,editing with SaCas9 led to higher efficiencies of NHEJ-mediated double-stranded oligodeoxynucleotide(dsODN)insertion or homology-directed repair(HDR)-mediated adeno-associated virus serotype 6(AAV6)donor knock-in.Finally,GUIDE-seq analysis revealed that SaCas9 exhibited significantly reduced off-target effects compared with SpCas9.Our work indicates the superior performance of SaCas9 to SpCas9 in transgene integration-based therapeutic gene editing and the necessity to identify the optimal spacer length to achieve desired editing results.
文摘With their capability to undergo unlimited self-renewal and to differentiate into all cell types in the body, human embryonic stem cells （hESCs） hold great promise in human cell therapy. However, there are limited tools for easily identifying and isolating live hESC-derived cells. To track hESC-derived neural progenitor cells （NPCs）, we applied homologous recombination to knock-in the mCherry gene into the Nestin locus of hESCs. This facilitated the genetic labeling of Nestin positive neural progenitor cells with mCherry. Our reporter system enables the visualization of neural induction from hESCs both in vitro （embryoid bodies） and in vivo （ter- atomas）. This system also permits the identification of different neural subpopulations based on the intensity of our fluorescent reporter. In this context, a high level of mCherry expression showed enrichment for neural progenitors, while lower mCherry corresponded with more committed neural states. Combination of mCherry high expression with cell surface antigen staining enabled further enrichment of hESC-derived NPCs. These mCherry＊ NPCs could be expanded in culture and their differentiation resulted in a down-regulation of mCherry consistent with the loss of Nestin expression. Therefore, we have developed a fluorescent reporter system that can be used to trace neural differentiation events of hESCs.
基金This work was supported by grants from the National Key R&D Program and the National Natural Science Foundation of China(2019YFA0802503,91857203,2018YFA0800602)Collaborative Innovation Program of Shanghai Municipal Health Commission(2020CXJQ01).
文摘Excessive cholesterol absorption from intestinal lumen contributes to the pathogenesis of hypercholesterolemia,which is an independent risk factor for atherosclerotic cardiovascular disease.Niemann-Pick C1-like 1(NPC1L1)is a major membrane protein responsible for cholesterol absorption,in which the physiological role of vesicular endocytosis is still controversial,and it lacks a feasible tool to visualize and evaluate the endocytosis of NPC1L1 vesicles in vivo.Here,we genetically labeled endogenous NPC1L1 protein with EGFP in a knock-in mouse model,and demonstrated fluorescent visualization and evaluation of the endocytic vesicles of NPC1L1-cago during intestinal cholesterol absorption.The homozygous NPC1L1-EGFP mice have normal NPC1L1 expression pattern as well as cholesterol homeostasis on chow or high-cholesterol diets.The fluorescence of NPC1L1-EGFP fusion protein localizes at the brush border membrane of small intestine,and EGFP-positive vesicles is visualized beneath the membrane as early as 5 min post oral gavage of cholesterol.Of note,the vesicles colocalize with the early endosomal marker early endosome antigen 1(EEA1)and the filipin-stained free cholesterol.Pretreatment with NPC1L1 inhibitor ezetimibe inhibits the formation of these cholesterol-induced endocytic vesicles.Our data support the notion that NPC1L1-mediated cholesterol absorption is a vesicular endocytic process.NPC1L1-EGFP mice are a useful model for visualizing cellular NPC1L1-cargo vesicle itineraries and for evaluating NPC1L1 activity in vivo in response to diverse pharmacological agents and nutrients.
