Thesis
Interplay between microRNA and hepatitis B virus replication
Master of Science (M.S.), Drexel University
May 2013
DOI:
https://doi.org/10.17918/etd-4239
Abstract
Chronic infection with the hepatitis B virus (HBV), which affects 350 million people worldwide, is an important global health issue. Virus-mediated changes in normal cellular physiology of hepatocytes, the main target cell of HBV, are considered to facilitate persistent and chronic infection of HBV, potentially leading to the development of HBV-associated liver cancer. Recent work with microRNAs (miRNAs) has shown that many cell types express distinct profiles of miRNAs specifically suited for regulating normal cellular function. This is particularly apparent in hepatocytes, where a single miRNA, mircoRNA-122 (miR-122), makes up at least 50% of the total miRNAs in the cell. Given the important role of miRNAs in regulating cellular function, and the particular importance of miR-122 to hepatocytes, we hypothesize that the levels of miR-122 in the cell may directly influence HBV replication, which may in turn regulate levels of miR-122. To address this hypothesis, the expression levels of miR-122 in HepG2.215 cells, which stably express HBV, were compared to their parental cell line, HepG2. Levels of miR-122 were significantly higher in HepG2.215 cells compared to HepG2. We then measured miR-122 using a luciferase reporter system in which luciferase activity is directly proportional to the amount of functional miR-122. These results, however, indicated minimal alteration of levels of miR-122 between these two cell lines. Also, when HepG2 cells were transfected with a plasmid expressing the HBV genome, HBV failed to elevate miR-122 levels, despite the presence of HBV proteins. On the other hand, exploring the effects of miR-122 expression on HBV replication showed that miR-122 enhanced HBV replication in transfected HepG2 cells in a dose dependent manner. These results may help explain why HBV specifically infects hepatocytes, the only cell type known to express significant levels of miR-122. Additionally, an assay was developed to confirm the authenticity of isolated primary rat hepatocytes using real-time reverse transcription-polymerase chain reaction for hepatocyte specific markers. Future work will replicate these miR-122 experiments in this more biologically relevant system. Together, while the effect of HBV infection on miR-122 expression remains controversial, these results do suggest a potential role for miR-122 in enhancing HBV replication.
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Details
- Title
- Interplay between microRNA and hepatitis B virus replication
- Creators
- Yi Guo - DU
- Contributors
- Michael Bouchard (Advisor) - Drexel University (1970-)
- Awarding Institution
- Drexel University
- Degree Awarded
- Master of Science (M.S.)
- Publisher
- Drexel University; Philadelphia, Pennsylvania
- Resource Type
- Thesis
- Language
- English
- Academic Unit
- School of Biomedical Engineering, Science, and Health Systems (1997-2026); Drexel University
- Other Identifier
- 4239; 991014632596804721