miR-30c and miR-193 are a part of the TGF-β-dependent regulatory network controlling extracellular matrix genes in liver fibrosis

Plasma microRNAs expression profile in female workers occupationally exposed to mercury

BACKGROUND

Circulating microRNAs (miRNAs) have attracted interests as non-invasive biomarkers of physiological and pathological conditions. Several studies have examined the potential effects of mercury exposure on miRNAs expression profiles of general population environmentally exposed to mercury. The objective is to identify mercury-related miRNAs of female workers occupationally exposed to mercury.

METHODS

In this case-control study, we used a microarray assay to detect the miRNA expression profiles in pooled plasma samples between (I) chronic mercury poisoning group; (II) mercury absorbing group and (III) control group in the discovery stage. Each group has ten individuals. In addition, we conducted a validation of eight candidate miRNAs in the same 30 workers by quantitative real-time PCR.

RESULTS

In the discovery stage, eight miRNAs were conformed following our selection criteria. In the validation stage, RT-PCR confirmed up-regulation of miR-92a and miR-486 in the mercury poisoned group (P<0.05) compared to the other two groups. The results were consistent with the microarray analysis.

CONCLUSIONS

Plasma miR-92a-3p and miR-486-5p might prove to be potential biomarkers to indicate responses to mercury exposure. However, further studies are necessary to prove the causal association between miRNAs changes and mercury exposure, and to determine whether these two miRNAs are clear biomarkers to mercury exposure.

Changes in interconnected pathways implicating microRNAs are associated with the activity of apocynin in attenuating myocardial fibrogenesis

Myocardial fibrosis is the endpoint pathology common to many cardiovascular disorders. We have previously shown that apocynin (APO), a naturally occurring NADPH oxidase inhibitor, significantly prevents the development of isoproterenol (ISO)-induced myocardial injury and fibrogenesis. The current study investigated the changes in microRNAs (miRNAs) and their potential implication in the cardioprotective effects of APO. Integrative analyses of whole-genome miRNA and gene expression profiles were first performed, revealing that altered expression of miRNAs likely contributed to dysregulated expression of genes associated with multiple interconnected fibrogenic signaling pathways. Importantly, APO treatment exhibited a broad impact on these signaling pathways, which could in part be mediated through miRNA-mediated gene expression regulation. The expression of differentially expressed miRNAs was further validated by real-time PCR analyses. Consistent with the data from miRNA array, compared to that from vehicle-treated normal controls, significantly decreased expression of miR-10b, miR-29c*, miR-30c-1*, miR-30e*, miR-148b, miR-181d, miR-218 and miR-3107* was observed in ISO-challenged vehicle-treated mouse hearts. In contrast, significantly increased expression of these miRNAs was observed in ISO-challenged APO-treated hearts compared to that from ISO-challenged vehicle-treated mice. Moreover, increased expression of miR-21 was observed as a result of ISO administration, which was significantly reduced by APO treatment. Altered protein levels of Col1, TIMP1, Rac2 and gp91(phox) were also validated. Lastly, APO treatment was shown to attenuate pre-established myocardial fibrosis induced by ISO. The results therefore demonstrated for the first time that complex changes in miRNA-mRNA interactome network are associated with the protective effects of APO against ISO-induced myocardial injury and fibrogenesis.

Blocking TGF-β expression inhibits silica particle-induced epithelial-mesenchymal transition in human lung epithelial cells

The main characteristic of silicosis is irreversible fibrosis. Certain studies have shown that epithelial-mesenchymal transition (EMT) regulated by transforming growth factor-β (TGF-β) is involved in fibrosis. Thus, we suggest that TGF-β regulated EMT may play an important role in silicosis. In this study, we determined the expression of TGF-β-Smad2/3, EMT- and ECM-related markers in lung epithelial cells treated with silica particle by RT-PCR, western-blot and ELISA. In order to explore the role of TGF-β, we used TGF-β inhibitor in the cell model. We found that the cells lost the expression of epithelial phenotypic markers and acquired increased expression of mesenchymal cells markers with ECM deposition after treatment with silica particle. Moreover, the changes of EMT-related event was restricted in response to TGF-β inhibitor. These findings suggest that EMT is essentially involved in the pathogenesis of fibrosis induced by silica particles and down-regulating the TGF-β expression can inhibit the process of EMT.