Cacna2d3通过调节巨噬细胞自噬功能参与结核菌感染的机制研究

Autophagy plays an important role to clear pathogens and control infection in TB infection .Calcium signal transduction is an important pathway for regulating autophagy.Cacna2d3（α2-δ3）is a calcium channel protein subunits, the main function is to start the transport of calcium. Gene α2-δ3 is known as a tumor suppressor gene, however, what's the role of α2-δ3 in TB infection process has not been reported. Our preliminary findings:1） the expression of α2-δ3 was significantly reduced in the H37Rv infected macrophages and the PBMC of TB patients;2)deletion of α2-δ3 can suppress the autophagosome formation in macrophages infected with TB; 3） the disease was aggravated in α2-δ3 deficient mice infected with TB. These results suggest that α2-δ3 involved in regulating the TB infection process by regulating autophagy, but the mechanism of its regulation of autophagy is unclear. Therefore, here we will explore the functional role of α2-δ3 in the process of Mtb infection of host macrophages and pathogenesis of tuberculosis by combining utilization of macrophage and mouse infection model as well as clinical samples analysis, and clarify the underlying modulation mechanism. This research will finally provide novel molecular target and intervention for the prevention and treatment of tuberculosis.

结核菌感染引起的细胞自噬对于机体清除病原菌、控制感染起着非常重要的作用。钙离子信号转导是调控自噬的重要途径。Cacna2d3（α2-δ3）是钙离子通道蛋白的亚基，启动钙通道的运输，属肿瘤抑制基因，但是，其在结核菌感染过程中的作用未见报道。我们前期研究发现：1）在H37Rv感染的巨噬细胞及TB病人PBMC中α2-δ3的表达明显降低； 2）α2-δ3基因突变抑制H37Rv感染时巨噬细胞自噬体的形成；3）α2-δ3基因突变小鼠感染结核菌后肺部组织学病变加重、荷菌量增加。以上研究结果提示结核菌可能通过调节α2-δ3，进而影响细胞自噬功能及结核菌的感染过程。为此，本项目将进一步从分子水平、细胞水平、动物感染模型及临床样本分析等不同层次，研究α2-δ3在结核菌感染及致病过程中的功能及作用机制，为结核病的预防与治疗提供新的分子靶标和研究思路。

肺结核（TB）由结核分枝杆菌感染引起的一个重要的公共卫生问题，每年有960万的新发病例和150万人死亡。MicroRNAs（miRNAs）虽然已被证明能调节肺结核发病，但是miRNA调节结核菌胞内存活的机制仍然是知之甚少。我们的研究表明，活动性肺结核患者外周血单核细胞，结核分枝杆菌感染小鼠肺组织，或结核分枝杆菌感染的巨噬细胞中miR-27a的表达与对照相比显著上调。miR-27a通过下调细胞自噬反应促进结核分枝杆菌的胞内存活，且miR-27a缺失小鼠或采用antagomir注射的小鼠能够抵抗结核分枝杆菌感染。miR-27a能直接靶向 cacna2d3的3’UTR区，而cacna2d3是电压门控性钙通道（VGCC）复合物的一个亚基。cacna2d3是通过Ca流介导的自噬反应调节结核菌的胞内存活，从而保护小鼠免受结核分枝杆菌感染。因此，我们的数据表明，结核杆菌感染可引起miR-27a的表达，从而下调cacna2d3介导Ca2+流和细胞自噬，从而促进结核分枝杆菌的胞内存活。我们发现miR-27a和cacna2d3作为结核菌感染的天然免疫中的新的调节分子，为抗结核的治疗方法提供新的依据。