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MIR144* inhibits antimicrobial responses against Mycobacterium tuberculosis in human monocytes and macrophages by targeting the autophagy protein DRAM2.

ABSTRACT: 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.

SUBMITTER: Kim JK

PROVIDER: S-EPMC5324854 | biostudies-literature | 2017 Feb

REPOSITORIES: biostudies-literature

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MIR144* inhibits antimicrobial responses against Mycobacterium tuberculosis in human monocytes and macrophages by targeting the autophagy protein DRAM2.

Kim Jin Kyung JK Lee Hye-Mi HM Park Ki-Sun KS Shin Dong-Min DM Kim Tae Sung TS Kim Yi Sak YS Suh Hyun-Woo HW Kim Soo Yeon SY Kim In Soo IS Kim Jin-Man JM Son Ji-Woong JW Sohn Kyung Mok KM Jung Sung Soo SS Chung Chaeuk C Han Sang-Bae SB Yang Chul-Su CS Jo Eun-Kyeong EK

Autophagy 20161020 2

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 ...[more]

PMID: 27764573

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Project description:Tuberculosis is one of the most important infectious diseases worldwide and macrophage apoptosis is the major host defense mechanism against TB. We attempted to characterize the role of miRNA (miR)-125b-5p on mycobacterium tuberculosis (Mtb) infection and macrophages behaviors in vitro. According to fluorescence-activated cell separation (FACS), primary monocytes (CD14+) in TB patients were accumulated, and apoptotic monocytes were decreased. Peripheral blood mononuclear cells (PBMCs)-derived macrophages (MDMs) and monocytic cells THP-1-derived macrophage-like cells (TDMs) in vitro were used to be infected with H37Rv. After infection, colony-forming units assay revealed the increase of bacterial activity, FACS demonstrated the decrease of apoptosis rate of MDMs and TDMs, as well as promoted levels of IL-6, TNF-α, Bax, and Bim and suppressed levels of IL-10 and Bcl-2, examined by enzyme-linked immunosorbent assay (ELISA) and western blot assay. Expression of miR-125b-5p and DNA damage-regulated autophagy modulator 2 (DRAM2) was examined, and real-time PCR and western blot assay showed that miR-125b-5p was upregulated, whereas DRAM2 was downregulated in primary monocytes and H37Rv-infected macrophages (MDMs and TDMs). Moreover, blocking miR-125b-5p could attenuated H37Rv-induced bacterial activity and inflammatory response of MDMs and TDMs, accompanied with apoptosis inhibition. Whereas these effects of miR-125b-5p knockdown were abolished by downregulating DRAM2. In mechanism, DRAM2 was a downstream target of miR-125b-5p, as evidenced by dual-luciferase reporter assay. Collectively, silencing miR-125b-5p could protect human macrophages against Mtb infection through promoting apoptosis and inhibiting inflammatory response via targeting DRAM2, suggesting a novel target for Mtb eliminating. Abbreviations: TB: tuberculosis; PBMCs: peripheral blood mononuclear cells; Mtb: mycobacterium tuberculosis; AFB: acid fast bacilli; FITC: fluorescein isothiocyanate; MDMs: monocytes-derived macrophages; TDMs: THP-1-derived macrophage-like cells; ERFP: Mtb-enhanced red fluorescent protein; CFU: colony-forming units; ELISA: enzyme-linked immunosorbent assay; FACS: fluorescence-activated cell separation; PI: propidium iodide; DRAM2: DNA damage-regulated autophagy modulator 2; Real-time PCR: real-time polymerase chain reaction; in-miR-125b-5p: miR-125b-5p inhibitor; si-DRAM2: siRNA against DRAM2.

Project description:The immune response to Mycobacterium tuberculosis infection determines tuberculosis disease outcomes, yet we have an incomplete understanding of what immune factors contribute to a protective immune response. Neutrophilic inflammation has been associated with poor disease prognosis in humans and in animal models during M. tuberculosis infection and, therefore, must be tightly regulated. ATG5 is an essential autophagy protein that is required in innate immune cells to control neutrophil-dominated inflammation and promote survival during M. tuberculosis infection; however, the mechanistic basis for how ATG5 regulates neutrophil recruitment is unknown. To interrogate what innate immune cells require ATG5 to control neutrophil recruitment during M. tuberculosis infection, we used different mouse strains that conditionally delete Atg5 in specific cell types. We found that ATG5 is required in CD11c+ cells (lung macrophages and dendritic cells) to control the production of proinflammatory cytokines and chemokines during M. tuberculosis infection, which would otherwise promote neutrophil recruitment. This role for ATG5 is autophagy dependent, but independent of mitophagy, LC3-associated phagocytosis, and inflammasome activation, which are the most well-characterized ways that autophagy proteins regulate inflammation. In addition to the increased proinflammatory cytokine production from macrophages during M. tuberculosis infection, loss of ATG5 in innate immune cells also results in an early induction of TH17 responses. Despite prior published in vitro cell culture experiments supporting a role for autophagy in controlling M. tuberculosis replication in macrophages, the effects of autophagy on inflammatory responses occur without changes in M. tuberculosis burden in macrophages. These findings reveal new roles for autophagy proteins in lung resident macrophages and dendritic cells that are required to suppress inflammatory responses that are associated with poor control of M. tuberculosis infection.

Dataset Information

MIR144* inhibits antimicrobial responses against Mycobacterium tuberculosis in human monocytes and macrophages by targeting the autophagy protein DRAM2.

Publications

MIR144* inhibits antimicrobial responses against Mycobacterium tuberculosis in human monocytes and macrophages by targeting the autophagy protein DRAM2.

Similar Datasets

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