结核分枝杆菌分泌蛋白Rv2647通过泛素化调控抑制巨噬细胞焦亡的机制研究

结核分枝杆菌(Mtb)在巨噬细胞(Mφ)中存活是结核病复发与传播的主要原因，Mφ焦亡是清除其存活的重要途径。Rv2647是Mtb的分泌蛋白，有关其影响Mφ焦亡的相关研究未见文献报道。我们前期研究发现：Rv2647刺激Mφ后，Mφ焦亡明显受抑，且Mφ对Mtb清除能力、NLRP3表达及Caspase-1活化皆显著下降，E3泛素连接酶ARIH2及TRIM31表达及NLRP3的K48位多聚泛素化修饰明显增强；此外，刺激后，miR-20/142表达显著下降，Akt磷酸化水平显著上升，PI3K抑制剂可逆转miR及Akt变化。据此，我们拟通过体内外研究证实如下机制：Mtb感染Mφ，Rv2647通过激活PI3K/Akt信号通路，下调miR-20/142表达，促进ARIH2及TRIM31表达，后两者靶向修饰NLRP3促进K48位多聚泛素化与降解，使Caspase-1活化受阻，从而抑制Mφ焦亡利于Mtb存活。

Tuberculosis is an important infectious disease that threatens human health.The main reason of the recurrence and spread of the disease is that M.tb could be survival in macrophages(Mφ),and the Mφ pyroptosis is an important way to eliminate it. Rv2647 is a secreted protein of M.tb, and no data have been focused on its influence on the host Mφ pyroptosis so far.Our preliminary results showed that the clearing ability of Mφ to M.tb was significantly reduced, the expression levels of pyroptosis marker p30-GSDMD and inflammasome NLRP3 was markedly decreased, the activation level of caspase-1was obviously declined, and the expression of E3 ubiquitin ligases ARIH2 and TRIM31 and K48 of NLRP3 polyubiquitination modifications were significantly enhanced after Rv2647 stimulated Mφ. In addition, miR-20 and miR-142 expression was decreased significantly, Akt phosphorylation was increased distinctly, while the PI3K inhibitors could reverse the changes of miRNA and Akt. As has been mentioned, we intend to confirm the following mechanism through in vivo and in vitro: M.tb secreted protein Rv2647 can down-regulates the expression of miR-20 and miR-142 by activating the PI3K/Akt signaling pathway, and promotes the expression of ARIH2 and TRIM31,which target modification of NLRP3 to promotes the K48 polyubiquitination and degradation, follow up blocking caspase-1 activation, thus inhibiting macrophage pyroptosis and benefit to M.tb survival.