Construction of Hsf1 gene-knockout mouse model using CRISPR/Cas9 / 中华骨科杂志

ABSTRACT

Objective:To explore the efficient construction of HSF1 gene knockout mouse model using CRISPR/Cas9 gene editing technology, and to establish the early basis for the mouse model of primary osteosarcoma.Methods:According to exon 9 of HSF1 gene structure, the corresponding GRNA (guideRNA) was selected and screened. Then the transcription template of sgRNA (small guide RNA) was amplified by PCR, and four up stream primers were obtained. Subsequently, sgRNA was transcribed in vitro and screened by Tube Screen platform to screen the sgRNA with effective cutting, and the sgRNA with the highest cutting efficiency was selected from the screening results for subsequent experiments. The transcription template of SPCas9mRNA was amplified by PCR, and then Cas9mRNA was transcribed in vitro. The sgRNA transcribed in vitro and Cas9mRNA were injected into the fertilized eggs of healthy C57BL/6 mice, and the tissue was extracted from the tail of the born mice and identified by PCR sequencing. Heterozygous female mice of F0 generation were selected to mate with wild-type male mice too btain F1 generation off spring. The mutation of gene bases of F1 generation mice was detected by AGAR gel electrophoresis and gene sequencing. The heterozygous male mice of the F1 generation and female mice of the F0 generation were back crossed to obtain the F2 generation daughter mice. The tail tissues were cut and sequenced to obtain the F2 generation homozygous knockout mice. PCR was used to observe the cutting efficiency of sgRNA and the sequencing of rat tail tissue, and SNAPGene software was used for gene sequence alignment to determine the deletion of base fragments.Results:The up stream primers sgRNA-1 Primer-f, sgRNA-2 Primer-f, sgRNA-3 Primer-f, sgRNA-4 Primer-f and down stream primers sgRNA-4 Primer -r were obtained by PCR amplification. After in vitro tran scription and screening of sgrRNA, sgrRNA-1, sgrRNA-2 and sgrRNA-4 had high cleavage efficiency and were selected for subsequent experiments. T7 promoter was added to the 5 'end of Cas9 mRNA, and Cas9 mRNA was obtained by PCR and in vitro transcription kit. Mixed Cas9-sgRNA solution was injected into the fertilized eggs of mice and cultured. The cultured two-cell fertilized eggs were injected into the ampulla of the pseudo pregnant female mice, and the F0 generation mice were obtained successfully. A total of 8 heterozygous mice of F0 generation were obtained by Agar gel electrophoresis. Three heterozygous knockout mice of F1 generation were obtained by breeding the female heterozygous mice of F0 generation with healthy wild-type male mice and PCR and sequencing. Three heterozygous male mice of F1 generation were back crossed with female mice of F0 generation 3 to obtain F2 generation mice. Through the observation of electrophoresis and sequencing results of F2 generation mice, it was confirmed that 7 mice were missing HSF1 base sequence, and the electrophoresis results showed mutant bands and no wild-type bands, which were identified as homozygous. The F2 generation homozygous mice were able to breed stably. As eries of results proved that the HSF1 gene knockout mouse model was successfully established in this experiment.Conclusion:CRISPR/Cas9 technology was successfully used to construct HSF1 gene knockout mouse model, with strong stability and high reproducibility, which laida foundation for further study of HSF1 gene expression products and establishment of mouse model of primary osteosarcoma.