IKKβ激酶的底物差异识别机制及其在炎症性肠病中的功能研究

经典型NF-κB通路在巨噬细胞介导的免疫应答中有着重要地位。IKKβ作为通路核心激酶，通过识别活化其下游底物p105、p65和IκBα等，参与多种病理生理过程，但其如何选择性识别这些底物的机制尚不明确。IKKβ的底物之一p105异常活化与炎症性肠病（IBD）的发病密切相关，其缺失小鼠有自发性结肠炎。我们前期研究发现，IKKβ的泛素化水平在炎症时显著升高，USP16、TRIM28等分子能调控IKKβ的泛素化水平，并诱发其选择性识别活化p105而不直接影响p65和IκBα的活化。基于USP16在IBD患者外周血单核细胞中的高表达，TRIM28的低表达，及巨噬细胞USP16特异性敲除的小鼠在肠炎模型中炎症更轻微等表型，本课题拟利用多品系条件性基因敲除小鼠探索IKKβ差异识别底物p105的具体机制，以助于更好了解NF-κB信号通路的调控模式，为阐明IBD的发病机制和实现靶向精准治疗提供理论基础。

The classical NF-κB pathway plays an important role in macrophage-mediated immune responses. IKKβ, as one of the core kinase, participates in a variety of pathophysiological processes by recognizing and activating its downstream substrates including p105, p65, and IκBα. But the mechanism of selectively recognizing these substrates by IKKβ is unclear. Hyperactivation of p105, one of the substrates of IKKβ, is tightly closed to the onset of inflammatory bowel disease (IBD). P105-deficient mice have spontaneous colitis. Based on our preliminary data, IKKβ ubiquitination is significantly elevated during inflammation, and mass spectrometry analysis identified various molecules, including USP16 and TRIM28, can regulate the ubiquitination level of IKKβ and induce its selective phosphorylation of p105 without affecting the activation of p65 and IκBα. A higher expression of USP16 and a lower expression of TRIM28 was observed in peripheral blood mononuclear cells of the patient with IBD than those in healthy donors. Macrophage-conditional USP16 knockout mice have milder colon inflammation in the experimental colitis model. This project intends to explore the mechanism of USP16 and TRIM28 regulate IKKβ selectively recognizes and activates substrate p105 with multiple conditional knockout mice. This study will provide a better understanding of the NF-κB signaling pathway regulation, and a theoretical basis and targeted precision therapy for the pathogenesis of IBD.