BACKGROUND: Exposure to methylmercury (MeHg) is predominantly attributed to consumption of marine products. However, the general population is exposed to low MeHg levels, which can induce chronic inflammation. Although some MeHg-related microRNAs (miRNAs) have been reported, their functions remain elusive. The objective of this study was to identify the miRNAs induced by low-level MeHg exposure in a human endothelial cell line (HAECs). This study aimed to determine the specific miRNAs induced by low-level MeHg exposure using a HAECs as a potential novel and sensitive biomarker. The roles of miRNAs in inflammatory processes have been examined. METHODS: Using HAECs, a miRNA microarray assay was performed to identify miRNAs with altered expression upon exposure to a non-cytotoxic MeHg level (0.1 and 1.5 µM). The expression patterns of interleukin-6 and -8, cyclooxygenase 2 (COX-2), RelB, and prostaglandin E₂ (PGE₂) were examined after transfection of the identified miRNAs with mimics/inhibitors. RESULTS: Although the microarray assay identified six MeHg-specific miRNAs, miR-3613-5p, upregulated by 0.1 and 1.5 µM MeHg exposures, demonstrated the best reproducibility in HAECs. Transfection with the miR-3613-5p mimic enhanced the MeHg-induced inflammatory responses, including PGE₂ and COX-2 protein levels, whereas the miR-3613-5p inhibitor suppressed these inflammatory responses. CONCLUSION This study observed that miR-3613-5p is induced by low-dose MeHg exposure, plays a crucial role in the inflammatory process, and could serve as a novel and sensitive biomarker for low-level MeHg exposure.
Methylmercury Compounds/adverse effects* ; Humans ; MicroRNAs/genetics* ; Endothelial Cells/metabolism* ; Inflammation/genetics* ; Cell Line ; Aorta/drug effects* ; Biomarkers/metabolism*

1) In problem-based learning (PBL) tutorials during the2nd year, general symptoms (fatigue, weight change, bleeding, fever, pain, and edema) were chosen as subjects.Changes in the students'way of thinking about how to learn were evaluated before and after PBL tutorials.
2) After tutorials students were significantly more likely to believe that their participation in tutorials was a more effective way of learning. The students'views after tutorials on listening to lectures differed between2006and2007.
3) We conclude that PBL tutorials affect medical students'views about learning.