Kim Jin Kyung, Lee Hye-Mi, Park Ki-Sun, Shin Dong-Min, Kim Tae Sung, Kim Yi Sak, Suh Hyun-Woo, Kim Soo Yeon, Kim In Soo, Kim Jin-Man, Son Ji-Woong, Sohn Kyung Mok, Jung Sung Soo, Chung Chaeuk, Han Sang-Bae, Yang Chul-Su, Jo Eun-Kyeong
a Department of Microbiology , Chungnam National University School of Medicine , Daejeon , Korea.
b Department of Medical Science , Chungnam National University School of Medicine , Daejeon , Korea.
Autophagy. 2017 Feb;13(2):423-441. doi: 10.1080/15548627.2016.1241922. Epub 2016 Oct 20.
Autophagy is an important antimicrobial effector process that defends against Mycobacterium tuberculosis (Mtb), the human pathogen causing tuberculosis (TB). MicroRNAs (miRNAs), endogenous noncoding RNAs, are involved in various biological functions and act as post-transcriptional regulators to target mRNAs. The process by which miRNAs affect antibacterial autophagy and host defense mechanisms against Mtb infections in human monocytes and macrophages is largely uncharacterized. In this study, we show that Mtb significantly induces the expression of MIR144*/hsa-miR-144-5p, which targets the 3'-untranslated region of DRAM2 (DNA damage regulated autophagy modulator 2) in human monocytes and macrophages. Mtb infection downregulated, whereas the autophagy activators upregulated, DRAM2 expression in human monocytes and macrophages by activating AMP-activated protein kinase. In addition, overexpression of MIR144* decreased DRAM2 expression and formation of autophagosomes in human monocytes, whereas inhibition of MIR144* had the opposite effect. Moreover, the levels of MIR144* were elevated, whereas DRAM2 levels were reduced, in human peripheral blood cells and tissues in TB patients, indicating the clinical significance of MIR144* and DRAM2 in human TB. Notably, DRAM2 interacted with BECN1 and UVRAG, essential components of the autophagic machinery, leading to displacement of RUBCN from the BECN1 complex and enhancement of Ptdlns3K activity. Furthermore, MIR144* and DRAM2 were critically involved in phagosomal maturation and enhanced antimicrobial effects against Mtb. Our findings identify a previously unrecognized role of human MIR144* in the inhibition of antibacterial autophagy and the innate host immune response to Mtb. Additionally, these data reveal that DRAM2 is a key coordinator of autophagy activation that enhances antimicrobial activity against Mtb.
自噬是一种重要的抗微生物效应过程，可抵御结核分枝杆菌（Mtb），这是一种导致结核病（TB）的人类病原体。微小RNA（miRNA）是内源性非编码RNA，参与各种生物学功能，并作为转录后调节因子靶向mRNA。miRNA影响人类单核细胞和巨噬细胞中抗菌自噬及宿主针对Mtb感染的防御机制的过程在很大程度上尚未明确。在本研究中，我们发现Mtb显著诱导MIR144*/hsa-miR-144-5p的表达，其靶向人类单核细胞和巨噬细胞中DRAM2（DNA损伤调节自噬调节剂2）的3'-非翻译区。Mtb感染下调了DRAM2在人类单核细胞和巨噬细胞中的表达，而自噬激活剂通过激活AMP激活的蛋白激酶上调了其表达。此外，MIR144的过表达降低了人类单核细胞中DRAM2的表达及自噬体的形成，而抑制MIR144则产生相反的效果。此外，结核病患者外周血细胞和组织中MIR144水平升高，而DRAM2水平降低，表明MIR144和DRAM2在人类结核病中的临床意义。值得注意的是，DRAM2与自噬机制的重要组成部分BECN1和UVRAG相互作用，导致RUBCN从BECN1复合物中被取代，并增强了磷脂酰肌醇3激酶（Ptdlns3K）的活性。此外，MIR144和DRAM2在吞噬体成熟及增强对Mtb的抗菌作用中起关键作用。我们的研究结果确定了人类MIR144在抑制抗菌自噬及宿主对Mtb的固有免疫反应中以前未被认识的作用。此外，这些数据表明DRAM2是自噬激活的关键协调因子，可增强对Mtb的抗菌活性。
