transposon mediated high-efficiency non-virus eukaryotic cell stable transfection method
阅读说明：本技术 一种转座子介导的高效非病毒真核细胞稳定转染方法 (transposon mediated high-efficiency non-virus eukaryotic cell stable transfection method ) 是由 周晓荣 丁晓凌 汪晓莺 于 2019-11-14 设计创作，主要内容包括：本发明提供一种转座子介导的高效非病毒真核细胞稳定转染方法,其特征在于通过构建了同时表达目的基因和转座酶SB100X的载体系统,在简化实验操作的同时,在真核细胞中提高了转座子介导的稳定转染效率。更具体的,本发明通过构建了单载体SB-2in1-DEST,用GFP为目的基因来测试,使稳定转染GPF的细胞比例比转座子双载体系统提高了约2.5倍,证明本发明的转染方法能显著提高非病毒稳定转染的效率。而且,本发明构建的SB-2in1-DEST载体,可以采用Gateway系统方便地将目的基因克隆进去,简化了克隆所需的技术和时间。(The invention provides a transposon-mediated high-efficiency non-viral eukaryotic cell stable transfection method, which is characterized in that a vector system for simultaneously expressing a target gene and transposase SB100X is constructed, and the transposon-mediated stable transfection efficiency is improved in eukaryotic cells while the experimental operation is simplified.)
A stable transfection method of transposon mediated high-efficiency non-viral eukaryotic cells, which is characterized by safety and high efficiency, comprising the following steps:
(1) by utilizing gene synthesis technology and service, synthesizing an EF1 promoter-driven SB100X expression vector, namely an EF1-SB100X vector, by taking a pbluescript vector as a template according to a published DNA sequence, and sequencing to identify the accuracy of the sequence;
(2) constructing a target gene with ITRs at two ends having terminal repetitive sequences, namely an ITR-CMV-GFP vector, by using a gene synthesis technology and service and taking a pbluescript vector as a template according to a published DNA sequence, and sequencing to identify the accuracy of the sequence;
(3) constructing an SB-2in1-DEST vector by using a PCR technology and by means of a multiple cloning site of a pbluescript vector, and sequencing to identify the accuracy of the sequence;
(4) utilizing Gateway technology to recombine the Entry clone expressing the target gene and SB-2in1-DEST to construct an SB-2in1-GFP vector, wherein the vector comprises ITR-CMV-GFP and EF1-SB100X sequences, and sequencing to identify the accuracy of the sequences;
(5) transforming EF1-SB100X, ITR-CMV-GFP or SB-2in1-GFP vector into DH5 α allelopathy strain;
(6) selecting single bacterial clone, amplifying for 16 hours in 3-5ml LB culture medium containing 100ug/ml ampicillin, extracting plasmid, sequencing again to verify the accuracy of the sequence;
(7) amplifying the verified clone in 100ml LB culture medium containing 100ug/ml ampicillin for 16 hours, extracting transfection-grade Plasmid by adopting PureLinkHiPure Plasmid Midiprep Kit, and measuring DNA concentration and purity;
(8) simultaneously transfecting two plasmids or SB-2in1-GFP plasmid in selected eukaryotic cells by using electrophoresis and Nucleofector of Lonza;
(9) after 10 days of cell expansion after transfection, the proportion of stably transfected cells in each group was identified by flow cytometry.
2. The method for stable transposon-mediated transfection of a non-viral eukaryotic cell as claimed in claim 1, wherein the target gene used in step (2) and step (4) is the GFP gene.
3. The transposon-mediated stable transfection method for high-efficiency non-viral eukaryotic cells as claimed in claim 1, wherein in step (3), the Gateway Clonase II is used to transfer the target gene GFP from the vector (Entry clone) directly into SB-2in1-DEST, thereby completing the construction of expression vector SB-2in 1-GFP.
4. The method for stable transfection of transposon-mediated non-viral eukaryotic cells as claimed in claim 1, wherein in step (5), the transformants are plated on agarose plates containing 100ug/ml ampicillin and cultured for 16 hours.
5. The stable transposon-mediated transfection method of claim 4, wherein 5ul of the bacterial suspension is inoculated.
6. The stable transfection method of transposon-mediated high efficiency non-viral eukaryotic cells as claimed in claim 1, wherein in step (6), 1ml of the bacterial solution is frozen in LB medium containing 20% glycerol at-80 ℃.
7. The method of claim 1, wherein step (7) is performed in a sterile environment.
8. The method of claim 1, wherein step (8) comprises using 3ug of plasmid in 100ul of cell suspension (10 ul)7/ml) was used.
Technical Field
The invention belongs to the technical field of genes, and particularly relates to a stable transfection method of transposon mediated high-efficiency non-viral eukaryotic cells.
Background
The stable transfection of eukaryotic cells has two types of viruses and non-viruses, and the method of using viruses as vectors has high efficiency, but the size of carried genes is limited, and the viruses have potential carcinogenicity and are a remarkable safety hazard. The advantage of non-viral vectors is good safety, but the disadvantage is low efficiency. The ideal eukaryotic cell transfection technology requires both safety and high efficiency, but the current methods have defects, which is the technical bottleneck of gene modification of the current eukaryotic cells, especially primary eukaryotic cells.
The Transposon (Transposon) is a -type DNA fragment which can be inserted into other parts of genome DNA under the action of transposase, so it is also called "jump gene". by analyzing kinds of specific transposons SB of the Salmonidae family, Ivics et al find that the Transposon itself carries inactivated SB transposase genes, which results in that the DNA fragment in the Transposon cannot be transferred to other parts.
The SB system has become a powerful tool for genomics research at present, and the SB system mediated DNA integration is utilized to obtain cells for stably expressing a target gene, the SB transposase with the strongest effect at present is SB100X, moreover, besides good safety, other characteristics of the SB system are that large gene fragments can be loaded, which is also superior to viral vectors, as shown in FIG. 1, the prior SB system comprises two plasmids, are plasmids for encoding the SB transposase, and are plasmids for carrying the target gene, ITRs are arranged on both sides of the target gene, and after the two plasmids are jointly transfected, the target gene can be efficiently inserted into a genome to form integrated stable transfection.
As shown in FIG. 1, the SB system works on the principle that the current SB system comprises two vectors, encoding SB transposase (vector 1), ITRs (vector 2) containing a target gene and two ends, after cells are co-transfected, the SB transposase is expressed, the target gene is mediated to be cut off from the
Disclosure of Invention
The invention integrates the strongest SB100X transposase coding gene and the target gene into vectors to form an SB single vector system, obviously improves the efficiency of non-viral stable transfection, and can conveniently clone the target gene by adopting a Gateway system, thereby simplifying the technology and time required for preparing an expression vector.
The embodiment of the invention provides transposon mediated high-efficiency non-viral eukaryotic cell stable transfection methods, which comprise the following steps:
(1) by utilizing gene synthesis technology and service, synthesizing an EF1 promoter-driven SB100X expression vector, namely an EF1-SB100X vector, by taking a pbluescript vector as a template according to a published DNA sequence, and sequencing to identify the accuracy of the sequence;
(2) constructing a target gene driven by a CMV promoter and provided with ITR sequences at two ends, namely an ITR-CMV-GFP vector, by utilizing a gene synthesis technology and service and taking a pbluescript vector as a template according to a published DNA sequence, and sequencing to identify the accuracy of the sequence;
(3) constructing an SB-2in1-DEST cloning vector comprising ITR, EF1-SB100X sequences and sequences for Gateway cloning by means of the multiple cloning site of pbluescript vector using PCR technique;
(4) by using Gateway technology, the Entry clone for expressing the target gene GFP and the SB-2in1-DEST are recombined to construct an SB-2in1-GFP vector, and the sequencing identifies the accuracy of the sequence. The vector contains expression sequences of GFP and SB100X, and can enable SB100X to be transiently expressed after transfection, mediate GFP gene to be integrated into genome DNA, and finally achieve the effect of stable expression;
(5) taking 0.1ng of EF1-SB100X, ITR-CMV-GFP or SB-2in1-GFP vector, and transforming DH5 α competent strains according to the product instruction;
(6) selecting single bacterial clone, amplifying for 16 hours in 3-5ml LB culture medium containing 100ug/ml ampicillin, extracting plasmid, sequencing again to verify the accuracy of the sequence;
(7) the verified clones were amplified for 16 hours in 100ml LB medium containing 100ug/ml ampicillin, and transfection-grade plasmids were extracted using PureLinkHiPure Plasmid Midiprep Kit (Invitrogen Co.), and DNA concentration and purity were measured;
(8) simultaneously transfecting two plasmids or SB-2in1-GFP plasmid in selected eukaryotic cells by using electrophoresis and Nucleofector of Lonza;
(9) the transfected cells were expanded for 10 days and then the proportion of stably transfected cells was identified for each group using flow cytometry.
Wherein the target gene used in the step (2) and the step (4) is a GFP gene.
Wherein, in the step (4), the Gateway cloning enzyme Clonase II is used to directly transfer the target gene from the Entry clone to the SB-2in1-DEST, thereby completing the construction of the SB-2in1-GFP vector.
In step (5), the transformants were inoculated on agarose plates containing 100ug/ml of ampicillin, respectively, and cultured for 16 hours.
, inoculating to obtain 5ul bacterial liquid.
Wherein, in the step (6), 1ml of the bacterial liquid is frozen and stored at-80 ℃ by using LB culture medium containing 20% of glycerol.
Wherein, the step (7) is operated in a sterile environment.
The technical scheme of the invention has the following beneficial effects:
according to the invention, the single vector SB-2in1-GFP is constructed, so that the cell proportion of the GPF stably transfected is improved by about 2.5 times compared with a double-vector system, and the transfection method disclosed by the invention is proved to be capable of obviously improving the non-virus stable transfection efficiency. Moreover, the SB-2in1-DEST vector is constructed, a Gateway system can be adopted to conveniently clone the target gene, and the technology and time required by cloning are simplified.
Drawings
FIG. 1 is a schematic diagram of a prior art SB system in the background of the invention;
FIG. 2 is a diagram of the structure of the EF1-SB100X vector constructed in the present invention;
FIG. 3 is a diagram showing the construction of an ITR-CMV-GFP vector constructed in the present invention;
FIG. 4 is a diagram of the construction of SB-2in1-DEST vector constructed in the present invention;
FIG. 5 is a diagram showing the structure of an SB-2in1-GFP vector constructed in the present invention;
FIG. 6 is a schematic diagram showing the proportion of cells that are flow cytometer GFP-positive after 2 days and 10 days of transfection of HBEC cells in the present invention;
FIG. 7 is a graph showing the ratio of GFP-positive cells detected by
Detailed Description
In order to make the technical problems, technical solutions and advantages of the present invention more apparent, the following detailed description is given with reference to the accompanying drawings and specific embodiments.
The invention provides a stable transfection method of transposon mediated high-efficiency non-viral eukaryotic cells, which comprises the following steps:
(1) the accuracy of the sequence was identified by sequencing using gene synthesis technology and services, based on the published DNA sequence of SB100X gene (https:// www.addgene.org/34879 /), using pbluescript vector as template, to synthesize the EF1 promoter-driven SB100X expression vector, i.e., EF1-SB100X vector (FIG. 2). The EF1-SB100X vector was used to test the transfection efficiency of the two-vector system.
As shown in FIG. 2, the structure of EF1-SB100X vector is constructed on the frame of pbluescript vector, mainly includes expression sequences of EF1 α eukaryotic promoter and SB100X gene, downstream BGH polyA sequence is necessary for transcription termination, the vector also carries ampicillin resistance gene (AmpR) and its promoter (AmpR promoter), other sequences are necessary for the amplification of the vector in prokaryotic cell.
(2) By using gene synthesis technology and service, according to published ITR sequences (refer to https:// www.addgene.org/26553 /), and still taking pbluescript vector as a template, a green fluorescent protein GFP gene with ITR sequences at two ends is constructed, a eukaryotic cell strong promoter CMV is arranged at the upstream, an ITR-CMV-GFP vector is obtained (figure 3), and the accuracy of the sequence is determined by sequencing. The ITR-CMV-GFP is used for testing the transfection efficiency of the double-vector system, and the GFP gene can be replaced by other target genes in practical use.
As shown in FIG. 3, the ITR-GFP vector has the following structural formula: the vector was constructed in the frame of the pbluescript vector. Mainly comprises expression sequences of eukaryotic promoter CMV and GFP genes and ITR sequences at two ends. Downstream BGH polyA sequences are necessary for transcription termination. The vector also carries an ampicillin resistance gene (AmpR) and its promoter (AmpR promoter). Other sequences are necessary for the amplification of the vector in prokaryotic cells.
(3) By using PCR technology and gene synthesis technology and service, SB-2in1-DEST vector (FIG. 4) is constructed by means of multiple cloning sites of pbluescript vector, which contains ITR and EF1-SB100X sequence, among ITRs is the sequence Gateway cassette needed by Gateway cloning (refer to https:// block. edge. org/plasmids-101-Gateway-cloning). The target gene is rapidly transferred from vector (Entry vector) directly to SB-2in1-DEST vector (Destination vector) by using Gateway cloning enzyme, and the time needed for cloning can be greatly shortened by using Entry vector of commercial target gene.
As shown in FIG. 4, the structure of SB-2in1-DEST vector is constructed on the frame of pbluescript vector, which mainly includes two parts, part includes two ITR sequences upstream and downstream, eukaryotic promoter CMV, Gateway (attR 1-CamR-ccdB-attR 2) and downstream PolyA sequence, Gateway cassette is used for Gateway cloning of target gene to obtain integration and stable expression of target gene, the second part is expression sequence of EF1 α and SB100X gene, and downstream BGH polyA sequence for transient expression of SB100X, which also carries ampicillin resistance gene (AmpR) and its promoter (AmpR promoter), other sequences are necessary for the amplification of vector in prokaryotic cells.
(4) As described above, the GFP vector purchased from Addge was recombined with the SB-2in1-DEST in vector (pDONR 221_ EGFP, reference https:// www.addgene.org/25899 /) and SB-2in1-DEST using Gateway technology to construct the SB-2in1-GFP expression vector (FIG. 5). As shown in the figure, the SB-2in1-GFP vector contains ITR-CMV-GFP and EF1-SB100X sequences, and the sequencing identified the accuracy of the sequences.
As shown in FIG. 5, the structure of SB-2in1-GFP vector is shown, which is obtained by using the above-mentioned SB-2in1-DEST vector (Destination vector) and vectors containing GFP gene (Entry vector) using Gateway cloning method.SB-2 in1-GFP vector mainly comprises two parts. part is eukaryotic promoter, CMV expression sequence of GFP and downstream PolyA sequence, and upstream and downstream ITR sequence for inserting GFP into genomic DNA and stably expressing.A second part is expression sequence of EF1 α and SB100X gene, and downstream BGH polyA sequence for transiently expressing SBX.
(5) EF1-SB100X, ITR-CMV-GFP or SB-2in1-GFP vectors are transformed into DH5 α sensitive strains, transformed products are respectively inoculated on agarose plates containing 100ug/ml ampicillin, and are cultured for 16 hours, 5ul of bacteria liquid is inoculated in an inoculating loop, and the aim is to pick up a single clone.
(6) Individual colonies were picked and expanded in 3-5ml LB medium containing 100ug/ml ampicillin for 16 hours. And extracting plasmids, and sequencing again to verify the accuracy of the sequence. 1ml of the bacterial liquid was frozen and stored at-80 ℃ for a long period of time in LB medium containing 20% glycerol.
(7) The verified clones were amplified for 16 hours in 100ml LB medium containing 100ug/ml ampicillin, and transfection-grade Plasmid was extracted using PureLinkHiPure Plasmid Midiprep Kit (Invitrogen) according to the instructions, DNA concentration and purity were measured, and aseptic manipulations were performed.
(8) Two plasmids or the SB-2in1-GFP plasmid were transfected simultaneously in selected eukaryotic cells using the Electroporation and Nucleofector from Lonza (see examples 1 and 2 for details).
(9) The transfected cells were expanded for 10 days and harvested 106Cells, resuspended in 200ul PBS buffer, and then the proportion of stably transfected (GFP expressing) cells in each group was identified using flow cytometry. This time point assay was chosen because only stably transfected cells were GFP positive, while transiently transfected cells lost GPF expression during the amplification process.
The transfection method of the present invention is further illustrated at in conjunction with specific examples.
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