背景:溃疡性结肠炎(UC)是一种慢性,以粘膜炎症和肠上皮细胞(IEC)损伤为特征的不治之症。昼夜节律基因NR1D1与UC和上皮修复的关键线粒体自噬过程有关,关于其在UC线粒体自噬调节中的作用需要进一步探索。
方法:我们创建了时差小鼠模型,并用葡聚糖硫酸钠(DSS)诱导结肠炎,正在调查NR1D1的角色。还产生了肠特异性Nr1d1敲除小鼠。RNA测序,染色质免疫沉淀(ChIP),双荧光素酶报告基因测定有助于确定NR1D1对BNIP3表达的调节作用。通过透射电子显微镜评估IEC中的线粒体状态,而共聚焦显微镜评估了结肠组织和CCD841细胞中线粒体自噬相关蛋白的表达。通过流式细胞术测量细胞凋亡和活性氧(ROS)。
结果:我们观察到UC患者的IECs中NR1D1表达减少,在小鼠的时差和DSS暴露下加重。NR1D1消融导致免疫稳态被破坏,并降低了IECs中的线粒体自噬。NR1D1,通常是转录抑制因子,是BNIP3表达的正调节因子,导致线粒体自噬受损,细胞炎症,和凋亡。施用NR1D1激动剂SR9009改善结肠炎症状,主要通过纠正有缺陷的线粒体自噬。
结论:我们的结果表明NR1D1桥接了昼夜节律和UC,控制BNIP3介导的线粒体自噬并代表潜在的治疗靶标。它的激动剂,SR9009在缓解UC症状方面显示出希望。
BACKGROUND: Ulcerative colitis (UC) is a chronic, incurable condition characterized by mucosal inflammation and intestinal epithelial cell (IEC) damage. The circadian clock gene
NR1D1, implicated in UC and the critical mitophagy process for epithelial repair, needs further exploration regarding its role in mitophagy regulation in UC.
METHODS: We created a jet lag mouse model and induced colitis with dextran sulfate sodium (DSS), investigating
NR1D1\'s role. Intestinal-specific
Nr1d1 knockout mice were also generated. RNA sequencing, chromatin immunoprecipitation (ChIP), and dual-luciferase reporter assays helped ascertain NR1D1\'s regulatory effect on BNIP3 expression. The mitochondrial state in IECs was assessed through transmission electron microscopy, while confocal microscopy evaluated mitophagy-associated protein expression in colon tissue and CCD841 cells. Cell apoptosis and reactive oxygen species (ROS) were measured via flow cytometry.
RESULTS: We observed reduced NR1D1 expression in the IECs of UC patients, accentuated under jet lag and DSS exposure in mice.
NR1D1 ablation led to disrupted immune homeostasis and declined mitophagy in IECs.
NR1D1, usually a transcriptional repressor, was a positive regulator of BNIP3 expression, leading to impaired mitophagy, cellular inflammation, and apoptosis. Administering the NR1D1 agonist SR9009 ameliorated colitis symptoms, primarily by rectifying defective mitophagy.
CONCLUSIONS: Our results suggest that NR1D1 bridges the circadian clock and UC, controlling BNIP3-mediated mitophagy and representing a potential therapeutic target. Its agonist, SR9009, shows promise in UC symptom alleviation.