Circular RNA TRAPPC6B inhibits intracellular growth while inducing autophagy in macrophages by targeting microRNA-874-3p.

OBJECTIVES

Genetic and epigenetic mechanisms regulate antimicrobial immunity against (Mtb) infection.

METHODS

The present study assessed circular RNA TRAPPC6B (circTRAPPC6B) for antimicrobial immune functions and defined mechanisms wherein circTRAPPC6B regulates Mtb growth, autophagy and microRNA in macrophages.

RESULTS

The Mtb infection of monocytes/macrophages resulted in a significantly decreased level of circTRAPPC6B that inhibited intracellular Mtb growth in macrophages. Conversely, circTRAPPC6B expression enhanced autophagy or autophagy-associated protein LC3-II production in Mtb-infected macrophages. circTRAPPC6B-enhanced autophagy aggregation or sequestration was also observed in fluorescence hybridisation (FISH) analysis and confocal imaging. Mechanistically, circTRAPPC6B targets an inhibiting element miR-874-3p, as shown by bioinformatics, dual-luciferase reporter gene analysis and pull-down assay, respectively. Notably, miR-874-3p prohibited autophagy via suppressing autophagy protein ATG16L1 by binding to its 3'-untranslated region (UTR) in Mtb-infected macrophages and thus promoting intracellular Mtb growth. Concurrently, circTRAPPC6B enhanced autophagy in Mtb-infected macrophages by blocking the ability of miR-874-3p to inhibit ATG16L1. Thus, circTRAPPC6B antagonises the ability of to suppress expression and activate and enhance autophagy sequestration to restrict Mtb growth in macrophages.

CONCLUSION

The current findings suggested that both circTRAPPC6B and miR-874-3p mechanisms can be explored as potential therapeutics against Mtb infection.