Zhang Guoliang, Liu Xi, Wang Wenfei, Cai Yi, Li Shaoyuan, Chen Qi, Liao Mingfeng, Zhang Mingxia, Zeng Gucheng, Zhou Boping, Feng Carl G, Chen Xinchun
a Guangdong Key Lab for Diagnosis & Treatment of Emerging Infectious Diseases, Shenzhen Key Lab of Infection & Immunity, Shenzhen Third People's Hospital, Guangdong Medical University , Shenzhen , China.
b Department of Infectious Diseases and Immunology , Sydney Medical School, The University of Sydney , NSW , Australia.
Cell Cycle. 2016 Sep 16;15(18):2527-38. doi: 10.1080/15384101.2016.1215386. Epub 2016 Aug 5.
Induction of cell apoptosis is one of the major host defense mechanisms through which macrophages control Mycobacterium tuberculosis (Mtb) infection. However, the mechanisms underlying macrophage apoptosis triggered by Mtb infection are still largely unknown. In this study, a microarray profiling survey revealed 14 miRNAs were down-regulated in CD14+ monocytes from active pulmonary tuberculosis patients, and only the reduction of miR-20a-5p could be reversed after successful anti-tuberculosis treatment. Validation of miR-20a-5p expression was confirmed using real time qPCR. Moreover, miR-20a-5p expression also decreased in differentiated THP-1 macrophages after mycobacterial infection in vitro. Functional assays through forced or inhibited expression of miR-20a-5p in THP-1 macrophages demonstrated that miR-20a-5p functioned as a negative regulator of mycobacterial-triggered apoptosis. Importantly, inhibition of miR-20a-5p expression resulted in more efficient mycobacterial clearance from infected THP-1 macrophages while miR-20a-5p overexpression promoted mycobacterial survival. Mechanistically, miR-20a-5p was demonstrated to regulate Bim expression in a JNK2-dependent manner, unlike Bcl2, and luciferase assay showed JNK2 was a novel direct target of miR-20a-5p. Together, our findings indicate that downregulation of miR-20a-5p triggers macrophage apoptosis as a novel mechanism for host defense against mycobacterial infection.
细胞凋亡的诱导是巨噬细胞控制结核分枝杆菌（Mtb）感染的主要宿主防御机制之一。然而，Mtb感染引发巨噬细胞凋亡的潜在机制仍 largely未知。在本研究中，一项微阵列分析调查显示，活动性肺结核患者的CD14+单核细胞中有14种miRNA表达下调，而只有miR-20a-5p的表达降低在成功的抗结核治疗后可以逆转。使用实时定量PCR证实了miR-20a-5p表达的验证。此外，体外分枝杆菌感染后，分化的THP-1巨噬细胞中miR-20a-5p表达也降低。通过在THP-1巨噬细胞中强制或抑制miR-20a-5p的表达进行功能分析表明，miR-20a-5p作为分枝杆菌触发的凋亡的负调节因子发挥作用。重要的是，抑制miR-20a-5p的表达导致从感染的THP-1巨噬细胞中更有效地清除分枝杆菌，而miR-20a-5p的过表达促进分枝杆菌的存活。从机制上讲，与Bcl2不同，miR-20a-5p被证明以JNK2依赖的方式调节Bim表达，荧光素酶测定表明JNK2是miR-20a-5p的一个新的直接靶点。总之，我们的研究结果表明，miR-20a-5p的下调触发巨噬细胞凋亡，作为宿主抵抗分枝杆菌感染的一种新机制。
