Hill - Neurodegenerative diseases, extracellular vesicles and noncoding RNAs
Neurodegenerative diseases such as Alzheimer's, Prion and Parkinson's diseases have an increasing prevalence amongst our ageing population. Recent estimates suggest the numbers of Australians suffering from dementia is set to double to 500,000 individuals by the year 2030. Many of these diseases are associated with the misfolding of certain proteins into aberrant forms that are found in the brain tissues of individuals with these diseases. The Hill lab uses a combination of Biochemistry, Molecular and Cell Biology to investigate these diseases. We are interested in understanding the molecular mechanisms by which these proteins exert their neurodegenerative properties and in the case of prion proteins, gain their infectious properties.
Our lab is also interested in extracellular vesicles such as exosomes and microvesicles as vehicles for the transfer of misfolded proteins between cells. We also investigate the RNA content of these vesicles using next generation sequencing and have used this to develop potential diagnostics for prion and Alzheimer's diseases.
The role of extracellular vesicles in neurodegenerative diseases
Extracellular vesicles (EV) are released by cells and include exosomes, microvesicles and microparticles. These vesicles have been shown to contain many proteins associated with neurodegenerative diseases, including the prion protein (PrP), amyloid precursor protein (APP), Tau and α-synuclein. We are interested in investigating the mechanisms, of how these proteins are packaged into these vesicles and also how they transfer their contents between cells. In particular, we are interested in a class of EVs known as exosomes. This project will also investigate the role of modifiers in exosome biogenesis by altering their expression with RNAi, using a lentiviral delivery system in neuronal cells.
We are also using high-resolution cryo-electron microscopy to study the structure of exosomes isolated from neuronal cells and characterise their protein and RNA content using high throughput sequencing and proteomics techniques.
The use of exosomal biomarkers for the diagnosis of neurodegenerative diseases
This project involves developing a minimally invasive blood test for the early detection of neurodegenerative diseases such as Alzheimer's disease (AD) and Parkinson's disease (PD). Diagnostic tests for AD and PD need to be greatly improved in order detect the disease early and implement preventative strategies. The technology behind our work involves detecting a disease signature of RNA molecules called microRNA which can be isolated from small biological vesicles called 'exosomes' that travel in the bloodstream. Using 'Next-Generation' deep sequencing to identify all the microRNA species in patients' blood, microRNA biomarkers can be selected by comparing differences in microRNA profiles from AD and PD patients to healthy controls. These differences in microRNA profiles can be developed into a blood test to improve diagnostic tools.
As it is not possible to isolate brain material from live patients to test for neurodegeneration, the capture of exosomes in the bloodstream can be equivalent to non-invasive brain biopsy. Brain biomarkers would have to cross the blood brain barrier (BBB) which serves as a strict control point between the brain and blood. One possible mechanism whereby brain biomarkers such as microRNA can travel across the BBB is via exosomes. Our research aims to determine whether exosomes provides a vehicle for brain biomarkers to travel through the BBB where they can be detected in the blood.
How do highly conserved regions of PrP control prion formation?
Much remains to be understood about how the normal cellular isoform of the prion protein undergoes structural changes to become the disease associated form. We have developed several approaches to study this aspect of prion biology using cellular, molecular and biophysical techniques. We have refined a model based around a highly conserved region of the prion protein. This project will uses a combination of structural and cell biological approaches to investigate the mechanism of prion inhibition through this conserved region of the prion protein.
Molecular mechanisms of A-beta toxicity in Alzheimer’s disease ‐ a role for the prion protein?
Recently it has been demonstrated that PrP can act as a receptor for Aβ oligomers which are implicated in the pathogenesis of Alzheimer's disease. Aβ is derived from a larger protein called the amyloid precursor protein (APP). We have well established cell lines expressing different forms of PrP and APP (which generate Aβ). These will be used to investigate the interactions of different forms of Aβ with PrP using a combination of biochemical and cell biological assays to determine the molecular mechanisms underlying this interaction.