MicroRNA-144-3p inhibits autophagy activation and enhances Bacillus Calmette-Guérin infection by targeting ATG4a in RAW264.7 macrophage cells

PLoS One. 2017 Jun 21;12(6):e0179772. doi: 10.1371/journal.pone.0179772. eCollection 2017.

Abstract

MicroRNAs (miRNAs) are small noncoding nucleotides that play major roles in the response of host immune cells. Autophagy plays a key role in activating the antimicrobial host defense against Mycobacterium tuberculosis (M. tuberculosis). Whether miRNAs specifically influence the activation of macrophage autophagy during M. tuberculosis infection is largely unknown. In the present study, we demonstrate that Mycobacterium bovis Bacillus Calmette-Guérin (BCG) infection of macrophages leads to increased expression of miR-144-3p, which targets autophagy-related gene 4a (ATG4a), to inhibit autophagy activation and antimicrobial responses to BCG. Overexpression of miR-144-3p significantly decreased both mRNA and protein levels of ATG4a, inhibited the formation of autophagosomes in RAW264.7 cells and increased intracellular survival of BCG. However, transfection with miR-144-3p inhibitor led to an increase in ATG4a levels, accelerated the autophagic response in macrophages, and decreased BCG survival in macrophages. The experimental results of this study reveal a novel role of miR-144-3p in inhibiting autophagy activation by targeting ATG4a and enhancing BCG infection, and provide potential targets for developing improved treatment.

MeSH terms

  • 3' Untranslated Regions
  • Animals
  • Antagomirs / metabolism
  • Anti-Bacterial Agents / pharmacology
  • Autophagosomes / metabolism
  • Autophagy
  • Base Sequence
  • Cysteine Endopeptidases / chemistry
  • Cysteine Endopeptidases / genetics
  • Cysteine Endopeptidases / metabolism*
  • Macrophages / cytology
  • Macrophages / metabolism
  • Macrophages / microbiology
  • Mice
  • MicroRNAs / antagonists & inhibitors
  • MicroRNAs / genetics
  • MicroRNAs / metabolism*
  • Microscopy, Electron, Transmission
  • Microscopy, Fluorescence
  • Mycobacterium bovis / physiology*
  • RAW 264.7 Cells
  • Sequence Alignment
  • Sirolimus / pharmacology

Substances

  • 3' Untranslated Regions
  • Antagomirs
  • Anti-Bacterial Agents
  • MicroRNAs
  • Atg4a protein, mouse
  • Cysteine Endopeptidases
  • Sirolimus

Grants and funding

This work was funded by the National Natural Science Foundation of China (No. 31472168; No. 31160494) and the 2013 Clinical Laboratory Diagnosis Creative Group Open Project.