[Generation and phenotypic characterization of S100A9 gene knockout mice by CRISPR/Cas9-mediated gene targeting].

S100 calcium binding protein A9 (S100A9) is involved in a variety of biological processes such as inflammation and tumor cell migration and invasion regulation. The purpose of this study was to construct S100A9 gene-edited mice by using CRISPR/Cas9 technology, thereby providing an animal model for exploring the biological functions of this gene. According to the S100A9 gene sequence, the single-stranded small guide RNA (sgRNA) targeting exons 2 and 3 was transcribed in vitro, and a mixture of Cas9 mRNA and candidate sgRNA was injected into mouse fertilized eggs by microinjection. Early embryos were obtained and transferred to surrogate mice, and F0 mice were obtained and identified by PCR identification and gene sequencing. F0 mice were further mated with wild-type C57BL/6 mice to obtain F1 heterozygous mice, and then homozygous offspring were obtained through F1 mice self-crossing. Real-time PCR, Western blot and immunohistochemistry (IHC) were used to verify the expression and distribution of S100A9. In order to observe the pathological changes of mouse lung tissue using HE staining, an allergic asthma model was induced by ovalbumin from chicken egg white (OVA). The results showed that the 2 492 bp of exons 2, 3 of the S100A9 gene was successfully knocked out, and S100A9-/- mice with stable inheritance were obtained. Furthermore, it was found that S100A9 gene was highly expressed in the lung and spleen of wild-type mice. The expression of S100A9 mRNA and protein was not detected in the lung and spleen of S100A9-/- mice. However, compared with wild-type mice, the lungs of S100A9-/- mice showed a significantly worse inflammatory phenotype, and the proportion of eosinophils in bronchoalveolar lavage fluid (BALF) was significantly increased in response to the treatment of OVA. These results suggest we have successfully constructed a new strain of S100A9-/- mice, and preliminarily confirmed that the lack of S100A9 function can aggravate airway inflammation in asthmatic mice, providing a new mouse model for further study of S100A9 gene function.

Knockdown of KDM2A inhibits proliferation associated with TGF-ß expression in HEK293T cell.

Lysine-specific demethylase 2A (KDM2A, also known as JHDM1A or FBXL11) plays an important role in regulating cell proliferation. However, the mechanisms on KDM2A controlling cell proliferation are varied among cell types, even controversial conclusions have been drawn. In order to elucidate the functions and underlying mechanisms for KDM2A controlling cell proliferation and apoptosis, we screened a KDM2A knockout HEK293T cell lines by CRISPR-Cas9 to illustrate the effects of KDM2A on both biological process. The results indicate that knocking down expression of KDM2A can significantly weaken HEK293T cell proliferation. The cell cycle analysis via flow cytometry demonstrate that knockdown expression of KDM2A will lead more cells arrested at G2/M phase. Through the RNA-seq analysis of the differential expressed genes between KDM2A knockdown HEK293T cells and wild type, we screened out that TGF-ß pathway was significantly downregulated in KDM2A knockdown cells, which indicates that TGF-ß signaling pathway might be the downstream target of KDM2A to regulate cell proliferation. When the KDM2A knockdown HEK293T cells were transient-transfected with KDM2A overexpression plasmid or treated by TGF-ß agonist hydrochloride, the cell proliferation levels can be partial or completely rescued. However, the TGF-ß inhibitor LY2109761 can significantly inhibit the KDM2A WT cells proliferation, but not the KDM2A knockdown HEK293T cells. Taken together, these findings suggested that KDM2A might be a key regulator of cell proliferation and cell cycle via impacting TGF-ß signaling pathway.