| [Purpose]Bromodomain-containing protein7(BRD7) is a full-length novel gene cloned by our laboratory independently. More than ten years of work has confirmed that BRD7, a nuclear transcriptional regulation factor, regulates a variety of target genes, and invovles in different signaling pathways, inducing different biological phenotypes, such as inflammation, development, reproduction and tumorigenesis. The findings in recent years indicated that many tumor suppressor genes, such as PTEN, P53, PDCD4, not only have close relationship with the tumor initiation and development, but also participate in the immune response, inflammatory diseases and other physiological and pathological process. Therefore, based on the BRD7knockout mouse model, it is of great importance to study the effect and mechanism of BRD7involved in inflammation suppression, providing us insight into the mechanism and clinical diaginosis of a variety of inflammation related diseases.[method]We systematically studied the effects of BRD7knockout on the initiation of inflammation by using BRD7conditional knockout mouse model. As spleen is an important immune organ in mouse, we next investigated the gene expression profile differentially expressed in the spleens between KO and WT mice through the whole-genome microarray hybridization, and validated by real-time PCR. Moreover, we explored the role of BRD7in the inflammation pathogenesis by constructing the LPS-induced MEF cell inflammatory model and AOM/DSS induced ulcerative colitis animal model, and further confirmed BRD7-mediated pathways and some important inflammatory cytokines in MEF cells and mouse colitis tissues, including IL-6, TNFa, iNOS, CXCL1and p65, by employing qRT-PCR and immunohistochemical techniques.[Results]In this study, based on the BRD7knockout mouse model, we found that the BRD7-/-mice were susceptible to surface inflammation compared with the wild type mice, such as externalia inflammation, abdominal abscess and papillary cell tumor of tongue, by observing the external phenotype, and the significant enlargement of the spleens were found in KO mice, followed with the occurrence of hypersplenism and hemolysis phenomenon. The changes in these inflammatory phenotype and related immune organ morphology indicate a decreased immune function of BRD7-/-mice. The spleen gene expression profiles were constructed by using whole genome microarray techniques, and the target genes and signaling pathways were further screened out, of which the mRNA expression of IL-6, iNOS and CXCL1were significantly increased in spleen of BRD7-/-mice compared with the wild type mice, whereas the TNFa were significantly decreased. After stimulation by LPS, the mRNA expression of IL-6, iNOS, CXCL1were significantly increased in MEF cells obtained from BRD7-/-mice, whereas the TNFa expression were significantly decreased. Similarly, after AOM/DSS induced ulcerative colitis animal model, the inflammatory grade of colorectal in BRD7-/-mice was found to be higher than that of wild type mice. The immunohistochemistry staining showed that IL-6, iNOS, CXCL1and NF-κB/P65were significantly increased in BRD7-/-mice compared with that in wild type mice, and the TNFa expression were also significantly decreased in BRD7-/-mice. Meanwhile, nuclear staining of NF-κB/P65was obvious increasing in BRD7-/-mice, which was further confirmed by immunofluorescence assay, suggesting that BRD7knockout might be involved in the initiation of inflammation by mainly activating NF-κB signaling pathway.[Conclusion](1) It is the first time to find that BRD7knockout leads to the BRD7-/-mice susceptible to inflammation.(2) The ulcerative colitis mouse model has been successfully constructed by using AOM/DSS induced chemical modeling method.(3) BRD7knockout is involved in the initiation and development by activating NF-κB signaling pathway, which changed the expression of IL-6, TNFα, iNOS and CXCL1. |
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