Hepatitis C virus (HCV) infection is the leading cause of chronic hepatitis worldwide. Approximately 170 million people are chronically infected and at risk to develop fatal liver damage, such as liver cirrhosis and hepatocellular carcinoma. The core protein represents the putative viral nucleocapsid and influences many cellular functions. Importantly, transgenic mice expressing core accumulate intracellular lipids, a condition called steatosis, and develop hepatocellular carcinoma. We observed that a fraction of core colocalized with mitochondrial markers in core-expressing HeLa and in Huh-7 cells containing the full-length HCV replicon. Using immunoelectron microscopy and in vitro mitochondrial import assays, we showed that core is located on the mitochondrial outer membrane. A stretch of 10 amino acids within the hydrophobic C-terminus of processed core conferred mitochondrial localization when fused to green fluorescent protein. We seek to examine whether the presence of core at the surface of mitochondria directly influences mitochondrial functions. We will generate mutants in the mitochondrial targeting motif and examine their effect on cellular lipid accumulation and apoptosis. Our preliminary experiments show that wild type core markedly induced lipid droplet formation in Jurkat T cells. We further observed a strong proapoptotic effect of core in primary oral fibroblasts after treatment with apoptosis-inducing agents. The interaction of core with several candidate proteins located at the mitochondrial outer membrane will be examined. Potential core targets include carnitine palmitoyltransferase I, a rate-limiting enzyme involved in the uptake of fatty acids by mitochondria, and members of the Bcl-2 family of apoptosis regulators. We anticipate that our studies will help elucidate the mechanisms of how HCV core induces steatosis and hepatocellular carcinoma. ? ? ?

Agency
National Institute of Health (NIH)
Institute
National Institute of Allergy and Infectious Diseases (NIAID)
Type
Small Research Grants (R03)
Project #
5R03AI069090-02
Application #
7458068
Study Section
Special Emphasis Panel (ZRG1-IDM-G (90))
Program Officer
Koshy, Rajen
Project Start
2007-07-01
Project End
2009-06-30
Budget Start
2008-07-01
Budget End
2009-06-30
Support Year
2
Fiscal Year
2008
Total Cost
$95,648
Indirect Cost
Name
J. David Gladstone Institutes
Department
Type
DUNS #
099992430
City
San Francisco
State
CA
Country
United States
Zip Code
94158
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