Homo sapiens Raw sequence reads. Homo sapiens

GBP5, an interferon-stimulated gene, plays a crucial role in cell autonomous immunity against intracellular pathogens. Our previous studies have linked GBP5 to inflammatory bowel diseases, suggesting its involvement in driving inflammatory activities. Here, we aim to elucidate the underlying mechanism behind the pro-inflammatory role of GBP5. In mononuclear cell line THP-1, we observed that GBP5 deficiency led to reduced expression of numerous pro-inflammatory genes, and their restoration upon GBP5 re-introduction. In a GBP5 knockout mouse model fed with dextran sulfite sodium (DSS), we demonstrated that GBP5 deficiency mitigated colonic inflammation. For mechanistic insights, transcriptome analysis revealed that, altered gene expression in the GBP5 deficient THP-1 cells mirrored those of STAT1 activation. CHIP-seq analysis demonstrated that GBP5 is not a transcription factor. On the other hand, GBP5 stimulated STAT1 expression and facilitated its translocation from the cytoplasm to the nucleus. Further, co-immunoprecipitation followed by mass spectrometry identified STAT1 as a GBP5 binding protein, which was confirmed by Western blots. In conclusion, our findings establish GBP5 as a key trigger molecule for intestinal inflammation in inflammatory bowel diseases, with the pro-inflammatory effect mediated through STAT1. Furthermore, GBP5 may enhance STAT1 expression and promote its nuclear translocation.

鸟苷酸结合蛋白5（GBP5）作为一种干扰素刺激基因（interferon-stimulated gene），在对抗细胞内病原体的细胞自主免疫中发挥关键作用。我们此前的研究将GBP5与炎症性肠病相关联，提示其参与促炎活性的调控。本研究旨在阐明GBP5促炎作用的潜在分子机制。在单核细胞系THP-1中，我们观察到GBP5缺陷会导致众多促炎基因的表达水平下调，且在重新导入GBP5后，这些促炎基因的表达可恢复至基线水平。在喂食葡聚糖亚硫酸钠（dextran sulfite sodium，DSS）的GBP5敲除小鼠模型中，我们证实GBP5缺陷可显著减轻结肠炎症反应。为深入解析其分子机制，转录组分析显示：GBP5缺陷的THP-1细胞中发生的基因表达改变与STAT1激活后的基因表达谱高度一致。染色质免疫共沉淀测序（ChIP-seq）分析证实，GBP5并非转录因子。另一方面，GBP5可促进STAT1的表达，并推动其从细胞质转位至细胞核。进一步的免疫共沉淀联合质谱分析鉴定出STAT1为GBP5的结合蛋白，该结果经蛋白质印迹（Western blots）实验验证。综上，我们的研究结果确立了GBP5作为炎症性肠病中肠道炎症的关键触发分子，其促炎效应通过STAT1介导。此外，GBP5可增强STAT1的表达并促进其核转位。