Autophagy serves a pivotal role in host defense during fungal infections, and the contribution by toll-like receptor 2 (TLR2) has been well demonstrated. It has been reported that microRNA-344a-1-3p (miR-344a-1-3p) can directly target TLR2. However, the expression of TLR2 significantly decreases during Aspergillus fumigatus infection. Therefore, the specific role of miR-344a-1-3p in the host defense against A. fumigatus infection remains to be elucidated. In the present study, A. fumigatus infection increased the expression of TLR2 and induced autophagy, which was indicated by increasing expression levels of autophagy-related protein 5 (ATG5), Beclin-1, light chain 3 (LC3)-1 and LC3-II, as measured by western blot analysis, and an increased number of GFP-LC3 puncta, as measured by fluorescence. Following transfection with miR-344a-1-3p mimics and/or TLR2, miR-344b-1-3p significantly inhibited the expression of TLR2, Beclin-1, ATG5, LC3-I and LC3-II, whereas the overexpression of TLR2 significantly attenuated the inhibitory effect on autophagy by miR-344b-1-3p. Collectively, these findings demonstrate that A. fumigatus can be controlled by the induction of autophagy following de-repression of the expression of TLR2, mediated by miR-344a-1-3p.
Keywords: Aspergillus fumigatus; autophagy; microRNA-344a-1-3p; toll-like receptor 2.