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MicroRNA‑502‑3p promotes Mycobacterium tuberculosis survival in macrophages by modulating the inflammatory response by targeting ROCK1.

ABSTRACT: Tuberculosis (TB) is caused by Mycobacterium tuberculosis (M. tuberculosis) infection and has the highest mortality rate of any single infectious disease worldwide. The aim of the present study was to investigate the function of microRNA (miR)‑502‑3p in M. tuberculosis‑infected macrophages. The Gene Expression Omnibus database was used to analyze miR‑502‑3p expression in patients with TB and healthy individuals. THP‑1 and RAW 264.7 cells were transfected with miR‑502‑3p mimic, miR‑502‑3p inhibitor, pcDNA3.1‑ROCK1 or their negative controls. The expression levels of miR‑502‑3p and inflammatory cytokines were evaluated using reverse transcription‑quantitative PCR. The colony‑forming unit assay was performed to assess the survival of M. tuberculosis in macrophages, and Toll‑like receptor (TLR)4/NF‑κB signaling pathway‑associated protein expression levels were detected by western blotting. The nuclear translocation of NF‑κB p65 was detected via immunocytochemistry. TargetScan was used to predict the binding sites between miR‑502‑3p and ROCK1. The interaction between miR‑502‑3p and Rho‑associated coiled‑coil‑forming protein kinase 1 (ROCK1) was confirmed using a dual‑luciferase reporter assay; ROCK1 was demonstrated to be a direct target gene of miR‑502‑3p. Results from the present study demonstrated that miR‑502‑3p expression was significantly increased during M. tuberculosis infection in macrophages. Upregulation of miR‑502‑3p expression levels significantly enhanced the survival of intracellular M. tuberculosis. IL‑6, TNF‑α, and IL‑1β mRNA expression levels were significantly upregulated during M. tuberculosis infection but were downregulated by miR‑502‑3p overexpression. Moreover, miR‑502‑3p mimics transfection significantly downregulated TLR4/NF‑κB signaling pathway‑associated protein expression and significantly reduced nuclear transcription of NF‑κB in M. tuberculosis‑infected macrophages. ROCK1 overexpression reversed the miR‑502‑3p inhibitory effect on cytokine production in M. tuberculosis‑infected macrophages. In conclusion, miR‑502‑3p/ROCK1 may serve an anti‑inflammatory role and may improve the survival of M. tuberculosis within macrophages, which may provide a promising therapeutic target for TB.

SUBMITTER: Liu F

PROVIDER: S-EPMC8436224 | biostudies-literature |

REPOSITORIES: biostudies-literature

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Project description:Intracellular survival plays a central role in the pathogenesis of Mycobacterium tuberculosis. To identify M. tuberculosis genes required for intracellular survival within macrophages, an M. tuberculosis H37Rv plasmid library was constructed by using the shuttle vector pOLYG. This plasmid library was electroporated into Mycobacterium smegmatis 1-2c, and the transformants were used to infect the human macrophage-like cell line U-937. Because M. smegmatis does not readily survive within macrophages, any increased intracellular survival is likely due to cloned M. tuberculosis H37Rv DNA. After six sequential passages of M. smegmatis transformants through U-937 cells, one clone (p69) was enriched more than 70% as determined by both restriction enzyme and PCR analyses. p69 demonstrated significantly enhanced survival compared to that of the vector control, ranging from 2.4- to 5.3-fold at both 24 and 48 h after infection. DNA sequence analysis revealed three open reading frames (ORFs) in the insert of p69. ORF2 (1.2 kb) was the only one which contained a putative promoter region and a ribosome-binding site. Deletion analysis of the p69 insert DNA showed that disruption of ORF2 resulted in complete loss of the enhanced intracellular survival phenotype. This gene was named the enhanced intracellular survival (eis) gene. By using an internal region of eis as a probe for Southern analysis, eis was found in the genomic DNA of various M. tuberculosis strains and of Mycobacterium bovis BCG but not in that of M. smegmatis or 10 other nonpathogenic mycobacterial species. Sodium dodecyl sulfate-polyacrylamide gel electrophoretic analysis showed that all M. smegmatis eis-containing constructs expressed a unique protein of 42 kDa, the predicted size of Eis. The expression of this 42-kDa protein directly correlated to the enhanced survival of M. smegmatis p69 in U-937 cells. These results suggest a possible role for eis and its protein product in the intracellular survival of M. tuberculosis.

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MicroRNA‑502‑3p promotes Mycobacterium tuberculosis survival in macrophages by modulating the inflammatory response by targeting ROCK1.

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