Motor Neuron Disease and Neurodegenerative Diseases

Project 1: Molecular consequences of microglial iron-loading in motor neurone disease (MND)

Introduction

The role of excess iron (Fe) in Alzheimer's, Huntington's and Parkinson's disease has received considerable and ongoing attention as underscored by the recent successful clinical trial of the Fe-chelating drug Deferiprone in Parkinson's disease patients. High Fe has typically been linked to neurodegeneration via enhanced production of reactive oxygen species (ROS), leading to oxidative protein damage, lipid peroxidation and mitochondrial destabilisation. Biomarkers of these events are detectable in the major neurodegenerative conditions.

Microglial activation is a primary hallmark of neuroinflammation present in neurodegenerative conditions, including MND. Indeed, crosstalk between activated microglia and motor neurons is thought key to MND disease progression particularly when the neuroprotective microglial M2 phenotype changes to the M1 neurotoxic phenotype.    

Microglia are also known to play an important role in scavenging and safely storing excess Fe, thereby protecting neurons from the consequences of Fe-loading. However, microglial Fe accumulation probably triggers molecular events that can promote motor neuron degeneration. Our project examines these possibilities and tests whether Fe-lowering drugs reverse these negative effects.

Hypothesis:

  1. Microglial Fe loading results in a shift to the M1 neurotoxic phenotype and regulates the expression of disease-modifying proteins in MND.
  2. Lowering microglial Fe may be a useful therapeutic strategy in MND.

Aims:

  1. Determine the effect of Fe modulation on microglial activation and phenotype
  2. Determine how Fe levels change NF-kB activation (and its key downstream targets) in microglia, examining the resultant effects on motor neurons in co-culture and in vivo.

Research Plan:

A variety of cell-culture models will be used to dissect the role of Fe in shifting microglial phenotype and inducing expression of disease-modifying proteins. Co-cultures of motor-neurons and microglia will be used to test whether Fe modulation reduces motor neuron axon loss and death mediated by activated microglia. Advanced laser-ablation inductively coupled plasma-mass spectrometry (LA-ICP-MS) techniques will then be used to map Fe in relation to markers of inflammation, microglial phenotype and disease-modifying proteins. Other experiments in a MND mouse model will examine if Fe chelation can increase survival and prevent neuronal loss by reversing microglial activation and reducing the expression of disease-modifying proteins. 

Enquires:
Dr David Lovejoy / Professor Gilles Guillemin

Email: david.lovejoy@mq.edu.au / gilles.guillemin@mq.edu.au

Project 2:  Modulating the kynurenine pathway in Alzheimer's disease: a method of attenuating neuroinflammation and potential disease biomarker

Introduction

The two main pathological hallmarks of Alzheimer's disease (AD) include extracellular accumulation of β-amyloid, leading to senile plaques, and intraneuronal accumulation of hyperphosphorylated tau, leading to neurofibrillary tangles. It is also well appreciated that AD develops in a neuroinflammatory milieu which exacerbates progression. A consequence of neuroinflammation is activation of the kynurenine pathway (KP) of tryptophan (TRP) metabolism leading to the accumulation of the by-product quinolinic acid (QUIN). We have strong published and additional evidence that QUIN, an excitatory neurotoxin, is involved in neurodegenerative processes in AD.

Mechanistically, we demonstrated that QUIN increases tau phosphorylation and leads to tau-related cytoskeletal derangement. We also showed that activated microglia surrounding senile plaques produce neurotoxic amounts of QUIN and that this is involved in AD pathogenesis. We subsequently published studies detailing the mechanistic aspects of KP activation in AD which we subsequently corroborated with in-vivo findings.

Hypothesis:

As our data implicates KP overactivity in the pathogenesis of AD the current project addresses two key questions: i) Can KP inhibition attenuate the neuroinflammatory pathophysiology of AD? ii) Can modulations of the KP serve as prognostic or predicative AD biomarkers?

Aims:

  1. Determine how KP inhibition can reduce neuroinflammation, tau hyperphosphorylation and neurofibrillary tangle (NFT) in AD mouse models.
  2. Assess if KP metabolites in an Australian Imaging, Biomarkers and Lifestyle (AIBL) Flagship Study of Ageing cohort can be biomarkers of AD.

Methods:

We will use pharmacokinetic techniques to assess structurally diverse KP inhibitors to define BBB penetration and effective doses for in-vivo administration. PET imaging techniques will be used to follow neuroinflammation over disease course and in KP inhibitor intervention cohorts in AD mouse models. Immunohistochemical and molecular biology techniques (RT-PCR, Western blotting and ELISAs) will be used to assess impact of KP inhibition on AD pathophysiology. Cell culture models will be used to probe mechanisms by which KP metabolites exacerbate formation of amyloid-β and tau hyperphosphorylation. Biomarker studies will utilize world-leading analytical techniques to quantify KP metabolites.

Enquires:
Dr David Lovejoy / Professor Gilles Guillemin

Email: david.lovejoy@mq.edu.au / gilles.guillemin@mq.edu.au

Project 3: Investigating the involvement of cyanobacteria toxin BMAA in motor neuron disease

Overview

The research will focus on elucidating the potential role that BMAA (an amino acid produced by cyanobacteria but not by mammals) plays in neurodegenerative diseases. Indeed, there is mounting evidence that BMAA is associated with motor neuron disease and other pathologies of the nervous system but our molecular understanding is still lacking. Our group has privileged access to primary neuronal cells, including motor neurons. The candidate will thus be in the unique position to investigate the effects of BMAA directly on such cells. A combination of experimental and computational approaches is suggested. Cells will be grown and exposed to BMAA in controlled conditions. Their response will be tested using multiple technologies spanning immunohistochemistry, imaging and expression arrays. We are particularly interested in the effect of BMAA on neurite dynamics (extension/retraction, protein trafficking, formation of connections with other neurons).

Methods

This research will expose the candidate to DNA and RNA biology, advanced microscopy, image analysis, DNA methylation assays, western blots, HPLC, etc. Applicants should have some laboratory experience with strong biology knowledge and interest to learn new techniques.

There are 2 PhD positions for this project: one in collaboration with Dr. Pascal Vallotton at CSIRO and one with Dr Kenneth Rodgers at UTS.

Enquires:
Professor Gilles Guillemin

Email: gilles.guillemin@mq.edu.au

Project 4: The role of C9ORF72 in Amyotrophic Lateral Sclerosis

Overview:

Amyotrophic Lateral Sclerosis (ALS)/Motor Neuron Disease (MND) is a progressive neurodegenerative disease which causes weakness, muscle wasting, and breathing difficulties. Most patients die within 2 to 3 years of the first symptoms. Frontotemporal dementia (FTD) is the most common form of early onset dementia, and ALS/MND and FTD are disorders with clinical, genetic, and neuropathological overlap. However the exact mechanisms that trigger motor neuron degeneration in these disorders remain elusive. Recently, hexanucleotide (GGGGCC) repeat expansions in a non-coding region of C9ORF72 were identified to be the major cause of both familial ALS (~40%) and FTD (~20%) in Australia and worldwide and they are also present in sporadic ALS. C9ORF72 encodes a protein of previously unknown function, and how mutations in C9ORF72 lead to ALS and FTD also remain unclear. Recently our group made an important discovery when we was the first to describe the normal cellular function for C9ORF72: regulation of both autophagy and endosomal transport. This project will further define the molecular basis for the normal cellular role of C9ORF72 and how the repeat expansion triggers ALS. It will involve using advanced microscopy and other cell biology, molecular biology and protein chemistry techniques, including the use of animal disease models.
 

Enquires:
Professor Julie Atkin

Email: julie.atkin@mq.edu.au