Chen Ping, Zhu Hua, Mao Yujuan, Zhuo Mingxing, Yu Yali, Chen Min, Zhao Qiu, Li Lianyun, Wu Min, Ye Mei
Department of Gastroenterology, Zhongnan Hospital, Wuhan University, Wuhan, Hubei, China.
Hubei Clinical Centre & Key Laboratory of Intestinal and Colorectal Diseases, Zhongnan Hospital, Wuhan University, Wuhan, Hubei, China.
J Gastroenterol Hepatol. 2021 Oct;36(10):2850-2863. doi: 10.1111/jgh.15550. Epub 2021 May 29.
Epigenetic modification is an important part of the pathogenesis of inflammatory bowel disease (IBD). Some studies proved that p62 was involved in inflammatory response and upregulated in IBD patients, and histone modification plays an important role in regulating p62 expression. SETD8, a histone H4K20 methyltransferase, has been reported downregulated in some inflammatory diseases. Here, we investigated the role of SETD8 in the development of IBD and its underlying mechanisms.
An inflammatory cell model was established to elucidate whether SETD8 involved in inflammatory response in macrophages. Three percent dextran sodium sulfate-induced colitis murine model injection with SETD8 inhibitor was used in our study to investigate whether SETD8 inhibition can affect the progress of IBD. The expression of SETD8 and p62 was measured by qRT-PCR and western blot. The mRNA level of inflammatory cytokines was analyzed by qRT-PCR. In addition, chromatin immunoprecipitation-PCR was performed to identify the mechanism by which SETD8 regulates p62.
SETD8 expression obviously decreased in vitro, in vivo models and in IBD patients. In lipopolysaccharide-activated RAW264.7 cells, knockdown of SETD8 significantly increased the mRNA expression of inducible nitric oxide synthase, cyclooxygenase-2, TNF-α, IL-6, IL-1β, and MCP-1. Based on the dataset, we verified that p62 was a target gene of SETD8 and chromatin immunoprecipitation-PCR assay identified that silence of SETD8 distinctly decreases the H4K20me1 enrichment in the promoter of p62. Moreover, silencing of p62 partly reverses the SETD8 inhibition-mediated pro-inflammatory effect in vitro. Finally, SETD8 pharmacological inhibitor (UNC0379) aggravated the disease progression in dextran sodium sulfate-induced murine colitis.
Our findings elucidate an epigenetic mechanism by which SETD8 regulates the p62 expression and restrains the inflammatory response in colitis. Our result suggests that targeting SETD8 may be a promising therapy for IBD.
表观遗传修饰是炎症性肠病（IBD）发病机制的重要组成部分。一些研究证明，p62参与炎症反应且在IBD患者中上调，组蛋白修饰在调节p62表达中起重要作用。SETD8是一种组蛋白H4K20甲基转移酶，据报道在一些炎症性疾病中表达下调。在此，我们研究了SETD8在IBD发生发展中的作用及其潜在机制。
建立炎症细胞模型以阐明SETD8是否参与巨噬细胞的炎症反应。本研究使用3%葡聚糖硫酸钠诱导的结肠炎小鼠模型并注射SETD8抑制剂，以研究抑制SETD8是否会影响IBD的进展。通过qRT-PCR和蛋白质免疫印迹法检测SETD8和p62的表达。通过qRT-PCR分析炎性细胞因子的mRNA水平。此外，进行染色质免疫沉淀-PCR以确定SETD8调节p62的机制。
SETD8在体外、体内模型以及IBD患者中表达明显降低。在脂多糖激活的RAW264.7细胞中，敲低SETD8显著增加诱导型一氧化氮合酶、环氧化酶-2、TNF-α、IL-6、IL-1β和MCP-1的mRNA表达。基于数据集，我们验证p62是SETD8的靶基因，染色质免疫沉淀-PCR分析确定SETD8沉默明显降低p62启动子中的H4K20me1富集。此外，沉默p62在体外部分逆转了SETD8抑制介导的促炎作用。最后，SETD8药理学抑制剂（UNC0379）加剧了葡聚糖硫酸钠诱导的小鼠结肠炎的疾病进展。
我们的研究结果阐明了一种表观遗传机制，即SETD8调节p62表达并抑制结肠炎中的炎症反应。我们的结果表明，靶向SETD8可能是IBD的一种有前景的治疗方法。
