The major focus of Professor Lavin’s research lab is on the response to DNA damage. The lab investigates the integrity of the genome and the risks associated with different diseases. Their research has focused on rare genetic disorders which are characterized by neurodegeneration and cancer predisposition. 

A major emphasis has been on ataxia-telangiectasia (A-T) (also called Louis-Bar syndrome), a rare genetic disease passed down from generation to generation. This disease is characterised by defects with cell growth and division (cell cycle checkpoint defects), extreme cell sensitivity to radiation (radio-sensitivity), compromised or absent immune system (immunodeficiency), loss of the nervous system (neurodegeneration) and cancer susceptibility. 
 
A number of different projects are currently being investigated in association with the National A-T Clinic, Lady Cilento Children’s Hospital and The Wesley Hospital. 

These include the activation mechanisms of ataxia-telangiectasia-mutated (ATM) by oxidative stress; identification of ATM underlying substances both in the nucleus and in the cytoplasm; the role of ATM in protecting against lung disease; and how ATM protects against neurodegeneration. 

Professor Lavin’s group has also investigated other neurological disorders including ataxia oculomotor apraxia type 2 (AOA2) which overlaps with A-T. Senataxin, the protein defective in AOA2, has also been shown to play a key role in cell cycle control, and also in protecting the genome.   

A second major focus of the lab, in collaboration with Professor RA Gardiner, is the process of identifying biomarkers for the early detection and prognosis of prostate cancer. 

The third major area of research is designed to develop snake-venom derived products for therapeutic and diagnostic use. To overcome problems with conventional blood collection tubes, such as lack of clotting and potential contamination, a new serum tube has been developed for analyte determination. A snake prothrombin activator, OsPA, has been added to these tubes to enhance clotting. More recently, a new form of the prothrombin activator has been developed to replace native prothrombin activator. Other projects are also in the pipeline in collaboration with industry.  

Role of oxidative stress in pulmonary disease in ataxia-telangiectasia (A-T)

To determine whether increased susceptibility to H2O2-induced oxidative stress in airway epithelial cells contributes to lung disease in patients with A-T and to improve assessment of lung disease in these patients using a novel method of assessing airway obstruction. We will test the general hypothesis that oxidative stress arising from recurrent sinopulmonary infections with H2O2-producing S. pneumoniae and other microorganisms contributes to the development of lung disease in patients with A-T.

Use of stem cell models in A-T.

Stem cells play a key role not only in development and growth of organisms but also in building new tissues and replacing others after injury. Thus they have great potential in regenerative medicine for the development of new therapies in a variety of different disease types. We employed fibroblasts from patients with A-T to reprogram into bona fide A-T induced pluripotent stem cells (A-T iPSCs). We showed that A-T iPSCs recapitulate key features of the A-T cellular phenotype, including radiation-induced cell cycle defects and increased sensitivity to radiation. We are at present in the process of differentiating these iPSCs into cerebellar neurons in collaboration with Prof. Ernst Wolvetang, AIBN.
 

Genetic correction of A-T defect in stem cells.

Before the A-T stem cells can be used to correct the defect in patients, it is necessary to restore normal ATM activity. This can now be achieved using gene editing to correct the defective gene. One such approach is the CRISPR-Cas9 assisted homologous recombination mediated gene repair. CRISPR-Cas9 operates through targeted introduction of dsDNA breaks that allow strand invasion of a repair template. Since ATM is centrally involved in dsDNA break repair, homologous recombination in A-T stem cells may prove to be particularly challenging. These resulting, corrected stem cells will need to be checked for their efficacy and safety especially with respect to genomic sequence in animal models to confirm their therapeutic use in patients. These corrected stem cells from patients represent an important resource for use as an isogenic cell model for differentiation into neuronal cells of interest to screen for therapeutic agents.

Development of animal models to investigate disease mechanism in A-T.

Animal models are valuable to study in vivo aspects of A-T which are difficult or impossible to investigate in cell culture. Over the years many labs including ours created various animal models of A-T. ATM knockout (Atm-/-) mouse displayed some of A-T phenotypic characteristics: high propensity to develop lymphoid tumours, immunological abnormalities and infertility. We showed that Atm-/- murine Purkinje neurons have a reduced number of dendrites when cultured in vitro, however the Atm-/- mice did not recapitulate characteristic ataxia and neurodegeneration seen in human A-T patients. Therefore it is difficult to use Atm-/- mouse models to study functions of defective ATM protein in the nervous system. We have recently created a novel rat model characterized by some of the neurodegenerative phenotypes seen in patients with A-T. We are currently investigating mechanisms of neurodegeneration in this model.

A novel role for Rad50 in mitosis in protecting the integrity of the genome to minimise disease risk.

The MRN complex (Mre11/Rad50/Nbs1) rapidly recognises and localizes to DNA DSBs where it acts to recruit and assist in ATM activation. ATM, in the company of several other DNA damage response proteins, in turn phosphorylates all three members of the MRN complex to initiate downstream signalling. We have recently shown that Rad50 plays a novel role in entry to and exit from mitosis, independent of its role in the MRN complex. Investigations are underway to unravel the specific mechanism involved.

Role of senataxin in protecting against neurodegeneration: Development and use of model systems.

To date, only patient-derived lymphoblastoid cells, fibroblasts, and SETX knockdown cells have mostly been used to investigate AOA2, all of which are not the most suitable model to study the neurological phenotype. Recent disruption of the Setx gene in mice did not lead to neurobehavioral defects or neurodegeneration, making it difficult to study the etiology of AOA2. Thus, we have recently developed the first AOA2 neuronal model by reprogramming AOA2 patient fibroblasts using iPSC technology to study the role of senataxin in gene regulation and neurodegeneration in this syndrome.

Role of senataxin in RNA processing and gene regulation in meiosis.

We generated the first AOA2 mouse model and demonstrated that senataxin is essential for spermatogenesis, functioning at two stages in meiosis- during crossing-over in homologous recombination and in meiotic sex chromosome inactivation (MSCI). We uncovered a critical role for senataxin in transcriptional silencing and chromatin remodeling during meiosis, providing greater insight into its critical role in gene regulation to protect against neurodegeneration.

Pre-clinical development and commercialization of snake venom prothrombin activators to generate “superior serum”.

A serum tube has been developed for analyte determination to overcome problems with conventional serum tubes such as lack of clotting with anticoagulated patients and cellular contamination. A snake prothrombin activator, OsPA, has been added to these tubes to enhance clotting. More recently, a recombinant form of the prothrombin activator has been developed to replace native prothrombin activator to enhance blood clotting and analyte determination.
 

NHMRC

  • To investigate the role of ATM protein in protecting against neurodegeneration (APP1077989) 2015-2018.
  • Research Fellowship (APP1020028) Improving the health of children with A-T. 2012-2016.
  • Research Fellowship (APP1117655) Improving the health of children with A-T. 2017.

Other funding

  • ATM protects lung epithelial cells against oxidative damage: Implications for pulmonary disease. BrAshA-T Foundation, Australia (RM2016001474). 2016-2017.
  • Investigation of role of oxidative stress in pulmonary disease in ataxia-telangiectasia. The A-T Children’s Project, USA (RM2016000563). 2016-2018.
  • RAPClot: Transforming the blood collection tube market. Q-Sera Pty Ltd. 2012-2017.