The role of mitochondrial function and DNA mutation in chronic hepatitis B

This project proposal sets out a programme of work designed to study the role of mitochondria in chronic hepatitis B, which our knowledge of their nature and effects on viral replication and disease progression is unknown. We aim to study the change mitochondrial function and common mitochondrial DNA (mtDNA) mutation in patients with chronic hepatitis B and infer their clinical importance. Following this we will induce HBV infection in vitro and test the influence on mitochondrial function and mtDNA mutation. Finally, we will induce mitochondrial dysfunction via drug and RNA interference, and evaluate the influence on hepatitis B virus (HBV) replication. We expect this can answer the foundimental questions addressed on HBV virology and help us to develop a novel strategy through modify mitochondrial function to reduce HBV replication. Mitochondria are intracellular organelles responsible for energy supplyment through oxidative phosphorylation in liver. The major changes of mitochondrial dysfunction include the impairment of the electron transport chain, decreased ATP synthesis, and reduced hepatocyte tolerance towards stressing insults. It has been demonstrated that mitochondrial dysfunction can occur in normal liver and various liver diseases including alcoholic liver disease, nonalcoholic liver disease, chronic hepatitis C, cholestasis, hemochromatosis, and Wilson’s disease. In chronic hepatitis B, the data is relative limited. Current studies mainly focused on HBx protein which can localize to mitochondria, alter its tansmembrane potential and increase cell death. However, the very nature and effects of mitochondrial dysfunction and mtDNA mutation on chronic hepatitis B and HBV viral replication are still unknown. Our preliminary datas showed the impairment of cytochrome c oxidase (COX), a mainly mtDNA-encoded protein in respiratory chain, can occur in cirrhotic liver tissues from patients with chronic hepatitis B. The HBsAg expression was mainly observed in hepatocytes with normal COX activities, while the increased HBcAg nuclear expression was found in the COX defect tissues. These findings suggest a potential role of mitochondrial function in HBV replication. To clarify this, we have the following goals to achieve in three years: 1. To confirm the above findings by analyzing more patients. 2. To find the commom mtDNA mutations in chronic hepatitis B. 3. To test the change of mitochondrial function and mtDNA mutation in hepatocyte with HBV infection 4. To evaluate the effects of mitochondrial dysfunction on HBsAg and HBV DNA expression 5. To develop a novel strategy to reduce HBV replication by modifying mitochondrial function Our lab, the Liver Research Unit in Likuo Chang Gung Memorial Hosptal, is a well equipped research unit for liver diseases and HBV studies in Taiwan. Furthermore, we have recently purchased a new machine, seahorse XF24-3 analyzer, which can analyse the dynamic change of mitochondrial function in live cells. Our preliminary data suggested the potential roles of mitochondria in HBV replication. We believe this project can help us not only to understand the fundamental relationships between mitochondria and HBV, but also to find a novel strategy to fight against chronic hepatitis B by modifying mitochondrial function.

Project ID:PC10202-0912
External Project ID:NSC101-2314-B182-096-MY2