Mce3C促进结核分枝杆菌入胞及胞内存活的分子机制研究

Mycobacterium. tuberculosis can escape from immune surveillance and clearance so as to survive in host macrophage cells for long periods of time, but the underlying molecular mechanisms remain largely unknown. It is of great importance to investigate the molecular mechanisms underlying the invasion and intracellular survival of M. tuberculosis in macrophage cells to gain a better understanding of the pathogenesis of tuberculosis, as well as to identify novel anti-tuberculosis drug targets. Previous studies have suggested that the third operon of mammalian cell entry (mce3) from M. tuberculosis might play an important role in cell entry and intracellular survival of M. tuberculosis, but the specific function of certain individual proteins encoded by this operon (such as Mce3C) and the detailed regulatory mechanisms of them remain undefined. In this project, we will apply multiple methodologies and techniques of biochemistry and molecular biology, cell biology, and immunology into the investigation of the function of Mce3C during the invasion and intracellular survival of M. tuberculosis in macrophage cells. We will further identify Mce3C-interacting host molecules and elucidate their regulatrory roles in cellular functions such as cytoskeleton rearrangement, inflammation and immune response-associated signaling pathways, apoptosis and autophagy. This project would shed light on the molecular mechanisms of latent infection and pathogenesis of M. tuberculosis. It would also provide novel strategies and targets for the development of anti-tuberculosis drugs.

结核分枝杆菌感染宿主后可逃逸机体免疫系统的监视和清除而得以在巨噬细胞中长期存活，但其分子机制尚未完全明确。深入研究结核分枝杆菌入侵巨噬细胞及其在胞内存活的分子机制，对于阐明结核病的发病机制以及探寻抗结核新药靶具重要意义。以往研究提示：结核分枝杆菌的mce3操纵子可能与结核分枝杆菌入侵宿主细胞及胞内存活相关，但其编码的某些单个蛋白（如Mce3C）的确切功能和作用机制尚不清楚。在本项目中，我们拟综合应用生化与分子生物学、细胞生物学和免疫学等方法和技术确证Mce3C在结核分枝杆菌入侵宿主巨噬细胞及胞内存活过程中的功能。我们还将鉴定与Mce3C互作的宿主蛋白分子，并探寻Mce3C通过与特定宿主分子间相互作用进而调控宿主的细胞骨架重排、炎症免疫相关信号通路、凋亡和自噬等方面的功能及机制。该研究将有助于进一步揭示结核分枝杆菌潜伏感染和致病的分子机制，还将为抗结核药物研发提供新的策略和和靶标。

结核分枝杆菌（Mtb）可逃逸机体免疫系统的监视和清除而得以在巨噬细胞中长期存活，但其分子机制尚未完全明确。深入研究Mtb入侵巨噬细胞及其在胞内存活的分子机制，对于阐明结核病（TB）的发病机制以及探寻抗结核新药靶具有重要意义。以往研究提示：Mtb的mce3操纵子可能与Mtb入侵宿主细胞及胞内存活相关，但其编码的某些单个蛋白（如Mce3C）的确切功能和作用机制尚不清楚。本项目的主要研究内容和目标任务是确证Mce3C在Mtb入侵宿主巨噬细胞及胞内存活过程中的功能，鉴定与Mce3C互作的宿主蛋白分子，探寻Mce3C通过与特定宿主分子间相互作用进而调控宿主的细胞骨架重排、细胞凋亡等方面的功能及机制，为抗结核药物研发和优化提供理论基础和潜在靶点。我们在本项目执行期间紧扣目标任务进行了深入研究，并获得了一系列重要发现，主要包括：1）确证了Mce3C可促进分枝杆菌对巨噬细胞的粘附和入侵；2）鉴定了Mce3C的一系列宿主互作蛋白分子，并发现Mce3C通过RGD模序与宿主β2整联蛋白直接互作，进而激活β2整联蛋白-SFKs-Syk信号轴并促进Mtb入侵宿主细胞；3）发现Mce3C可在分枝杆菌感染时分泌到细胞质中，通过抑制宿主细胞凋亡并促进宿主细胞坏死进而促进Mtb胞内存活；4）发现Mce3C与宿主细胞中的Cathepsin B互作并通过与Cathepsin B重链结合进而抑制Cathepsin B的酶活并影响细胞凋亡和坏死。综上，该研究阐明了Mce3C促进Mtb入侵宿主细胞并在胞内存活的分子机制，揭示了胞内病原菌逃逸宿主固有免疫的新机制，为抗结核新药研发和优化提供了新思路和潜在新靶点。已在Nature Communications, Cellular & Molecular Immunology, Cellular Microbiology等重要杂志发表致谢了本项目的相关论文12篇。