Nrdp1在巨噬细胞抗结核感染中的作用及分子机制研究

Mycobacterium tuberculosis (Mtb) infection of macrophages can induce the apoptosis of host macrophages to generate a protective immune response against Mtb infection, while some of its special bacterial ingredients or secretory protein can inhibit the apoptosis of host macrophages to escape the killing by them. Therefore, to explore the key molecules in the regulation of apoptosis of host macrophage is important for understanding the pathogenesis and treatment of tuberculosis. Recently, we have found a new Nrdp1 interacting protein (NIP) to promote Nrdp1-mediated ubiquitination and degradation of inhibitory apoptosis protein BRUCE, moreover, the survival of Mtb in the NIP knockout MEF cells is promoted compared with wild type MEF cells, indicating that Nrdp1 and NIP may play important roles in the regulation of anti-Mtb infection by the host. Therefore, In this project, we aim to: 1) confirm whether NIP is involved in the process of anti-Mtb infection by promoting the Nrdp1 mediated ubiquitination and degradation of BRUCE; 2) further explore whether the ASK1, p38 and c-Abl are involved in the regulation of phosphorylation of BRUCE to regulate the apoptosis of macrophages. The study will reveal the roles and molecular mechanism of Nrdp1 in the host anti-Mtb infection, and the results from this study will provide novel information for the development of anti-TB drugs.

结核分枝杆菌(Mtb)感染巨噬细胞后，一方面可诱导宿主巨噬细胞凋亡及产生抗感染的保护性免疫反应，而另一方面其某些特殊菌体成分或分泌蛋白可抑制巨噬细胞凋亡而发生免疫逃逸。因此，探寻调控巨噬细胞凋亡的宿主关键分子对于了解结核病的发病和治疗意义重大。我们最近发现了Nrdp1的一个新的互作蛋白（命名为NIP)可促进Nrdp1介导的凋亡抑制蛋白BRUCE的泛素化和降解而促进细胞凋亡，且NIP缺失细胞中的分枝杆菌存活数明显高于野生细胞，提示Nrdp1和NIP可能在抗Mtb感染中起作用。因此在本项目中，我们拟：1）确证NIP是否可通过调控Nrdp1介导的BRUCE的降解及巨噬细胞凋亡而发挥抗Mtb感染作用；2）进一步探索ASK1等激酶是否可通过调控BRUCE的磷酸化而影响Nrdp1介导的抗Mtb感染作用。该研究将揭示Nrdp1在宿主抗结核感染中的作用及分子机制，并将为抗结核新药的研制提供新思路。

Nrdp1是一种Ring Finger家族的泛素连接酶，它可催化底物BRUCE的泛素化降解而导致细胞凋亡。我们发现的Nrdp1互作蛋白-NIP同样对细胞凋亡有显著的促进作用。因此我们推测NIP和Nrdp1可能通过促进细胞凋亡而在巨噬细胞抗结核分枝杆菌感染过程中起重要拮抗作用。为深入探寻NIP调控BRUCE泛素化及细胞凋亡的分子机制，我们在本研究中：1）确证NIP参与调控促进细胞凋亡；2）NIP对抑制分枝杆菌的胞内存活至关重要；3）NIP对结核分枝杆菌感染过程中部分细胞因子基因的转录激活是必需的。该研究揭示了宿主蛋白NIP在抗分枝杆菌感染过程中发挥重要作用，该成果将为抗结核药物的研究提供新思路。