Regulatory role of Notch signalling on hepatic stellate cells in the development of NASH and liver fibrosis
In this project, we aim to investigate the whether activation of HSCs is associated with enhanced expression and function of Notch signaling, and whether activation of HSCs and the production of fibrogenic molecules such as collagen I and TGF1 by HSCs is mediated by Notch signaling.
Primary liver cancer or hepatocellular carcinoma (HCC) is a classical example of inflammation-related malignancy as the vast majority of HCC cases were caused by chronic viral hepatitis. In Asian and African countries, chronic infection with hepatitis B virus (HBV) is the major cause for liver cancer, whereas in Western countries including Australia, chronic infection with hepatitis C virus is responsible for the vast majority of HCC cases. Overall, more than 75% of the HCC cases are caused by HBV and HCV infections. Apart from viral infections, other causes of HCC have been identified, among which nonalcoholic steatohepatitis (NASH), a severe form of nonalcoholic fatty liver disease (NAFLD), has been proposed as a serious pre-cancerous condition for HCC. In Western countries, NASH/NAFLD is the most common form of liver disease that causes abnormal liver function in clinical settings. NASH is characterized by fatty changes in the liver, inflammation and various degree of fibrosis. If persists for a long period of time, NASH may develop into end stage liver diseases mainly cirrhosis, even HCC.
During the development of NASH and liver fibrosis, hepatic stellate cells (HSCs) play a critical role. Although HSCs only constitute approximately 8-14% of cell populations in the normal liver, they are the primary site for retinoid storage and the principal cell type for the development of liver fibrosis. In response to hepatic inflammation, HSCs trans-differentiate from lipocyte-like cells into contractile and highly proliferative myofibroblast-like cells (this is the process of HSC activation). Activation of HSCs is responsible for the enhanced production of extracellular matrix (ECM), collagen 1, and transforming growth factor 1 (TGF1). Interestingly, in recent years, HSCs have been found to behave as stem cells. In this respect, liver fibrosis may be regarded as a stem cell disease. As the vast majority of HCC cases occur in the diseased liver especially liver fibrosis and cirrhosis, fibrosis may be a common process bridging the etiological factors with liver cancer. However, how HSCs are activated during liver fibrosis and how fibrosis eventually leads to end stage liver diseases including liver cancer remains unknown.
We have recently observed that in the methionine and choline deficient diet (MCD) diet induced liver injury and NASH in mice, there was an up-regulation of Notch signaling component genes such as Notch1 and Hes1. As Notch signaling is an important pathway that determines cell fate and differentiation, we therefore speculate that in response to inflammatory insults or liver injury, activation of HSCs may be associated with activation of Notch signaling which then decides whether the HSCs should undergo apoptosis or differentiate into activated form to produce fibrogenic molecules. However, direct evidence linking HSC activation and Notch signaling is still missing.
Isolation of and in vitro culture of rodent HSCs; culture of quiescent and activated human HSCs cell line;
Establishment of mouse model of NASH;
Basic molecular biological techniques such as extraction of total RNA and protein from cultured cells and tissues; reverse transcription of RNA to cDNA; quantitation of RNA and protein; real time PCR (qPCR); plasmid purification; bacterial transformation; cloning and sub-cloning; transfection of cells with siRNA and plasmids; Western Blotting;
Other cell biology techniques: histology, immunohistochemistry; light and fluorescence microscopy; cell proliferation assay; apoptosis assay; migration assay
About the Storr Liver Unit
The Western Clinical School's Storr Liver Unit investigates the pathogenesis of liver disease, and the diverse causes of liver injury, such as drugs and toxins, metabolic factors and viruses. Internationally acclaimed, the Unit has made substantial contributions to defining how the liver responds to injury, and how genes involved in the metabolisms of drugs and toxic products of liver metabolism are regulated.
Liver cancer is Australia's fastest growing cancer, and this is an opportunity to take a role in the research of this emerging health focus. The Unit is well funded and thus there is the opportunity to employed cutting edge techniques and tools to bring each project to fruition. Joining a successful research team with expertise in liver disease and cancer, there will also be opportunity to collaborate with internationally-renowned cancer researchers at the Westmead Millennium Institute. As part of the community of over 400 researchers based on the Westmead campus, there will be the possibility to utilise the Institute's state-of-the-art molecular, translational and cell biological facilities.
Want to find out more?
The opportunity ID for this research opportunity is: 1317
Other opportunities with Dr Liang Qiao