The role of the descending dopaminergic projection in spinal development and regeneration

Nerve cells (neurons) in the spinal cord may be lost after injury. In motor neuron diseases, motor neurons in the spinal cord also die, leading to progressive paralysis and death. The reason for the irreversibility of these conditions is that in the human spinal cord, stem cells fail to regenerate neurons. In contrast, we have shown that the zebrafish regenerates motor neurons and other neurons even in adults. It is therefore important to elucidate the signals that allow these animals such formidable tasks. We have recently described that a messenger molecule, dopamine, is able to augment the generation of motor neurons in zebrafish and in human embryonic stem cells in cell culture, indicating a degree of similarity of this signal between zebrafish and humans. Here we want to find out whether dopamine acts only on stem cells that generate motor neurons and which signals inside the stem cells, responsible for motor neuron generation, are involved. Moreover, we will determine how this dopamine signal allows correct movement patterns of the embryo to emerge during development and whether dopamine can be harnessed to improve swimming function after a loss of motor neurons. Our research thus aims to find new cascades of molecular signals that may be important to understand how the spinal cord in vertebrates develops and how these developmental signals can be re-deployed after injury or degenerative neuron loss, which may ultimately inform cell replacement therapies in injured or diseased patient spinal cords. Moreover, our research indicates that psycho-active drugs that act on dopamine signalling during critical phases of embryonic development may lead to permanent changes in spinal cord function of the embryo. This may inform future research into potentially harmful consequences of drug use during early stages of pregnancy.

In contrast to zebrafish, the human spinal cord is unable to generate new motor neurons with devastating consequences in neurodegenerative diseases or after spinal cord injury. We have recently discovered that dopamine is a long range signal that acts on spinal progenitor cells to increase motor neuron generation during development and after a spinal lesion in zebrafish (Reimer et al, Dev Cell, 2013, 25, 478). This action of dopamine is evolutionarily conserved, as in human stem cell cultures, dopamine signalling enhances motor neuron differentiation. Hence, it is important to determine which progenitor cell types and which subcellular signalling pathways dopamine acts on during developmental and regenerative neurogenesis. Moreover, with its requirement for early function, the zebrafish motor system is uniquely placed to allow us to address the functional consequences of altered dopamine signalling. We will use anatomical, electrophysiological and high-speed video assays to determine how dopamine affects spinal neurogenesis and motor function during critical phases of development and regeneration. Finally, we will perform expression profiling of highly purified progenitor domains to discover new pivotal genes for spinal neuron (re-)generation. This project aims to elucidate fundamental vertebrate mechanisms and genes involved in functional spinal cord development and regeneration. Therefore, our research will inform future therapeutic approaches to motor neuron degeneration and spinal injury. Moreover, knowledge of critical dopamine-dependent developmental phases for motor neuron generation may be relevant in the context of psychoactive drugs taken during pregnancy.

Communications and Engagement
CNR sponsors an exciting internal and external lecture series that includes Brain Awareness Week, Edinburgh Neuroscience Day, and the Annual Distinguished Lecture which are open to the public. The School of Biomedical Sciences also provide "Briefings" summaries of the research findings of each Principal Investigator written for a lay audience on its website.

Catherina Becker was a speaker at the Edinburgh Neuroscience Day 2008. Work from her laboratory has been the topic of university press releases in April 2009, January 2012 and May 2013, for which we closely worked with the University's press officer, Ms Tara Womersley. This led to National media coverage (BBC website and BBC radio, Herald, Telegraph, The Metro and others) and a blog by the MNDA. Our work has been covered in the University "Friends" magazine in January 2010 and the Packard Center's ALS-Alerts Spring 2009, Summer 2010 and 2013.

The Euan MacDonald Centre and MND Scotland have organised opportunities for their scientists to engage with patients, their relatives and other interested parties, including potential donors, which Dr Becker also attended and/or spoke at (for example the "Bash at the Brewery" in June 2009 and May 2011, MND Scotland Open Day in May 2010, MND Scotland Annual General Meetings since 2009). I also attend the annual meetings of the Packard Center for ALS Research at Johns Hopkins.

Regeneration Biology is a particularly attractive topic to engage pupils in science. We have run workshops for primary school pupils at a local school in their "Science Career Fair" and science lessons.

Collaboration
Our project will strengthen the scientific collaborations between the Sillar laboratory in St Andrews and the Becker group. This will allow the establishment of zebrafish electrophysiology in Edinburgh and exploit important synergies in expertise.

Exploitation and Application
The present project will investigate the specific actions of dopamine on spinal progenitor cells, which eventually shape the functioning locomotor system. This is a fundamental question in developmental biology and answering these questions may also lead to the identification of future therapeutic targets for spinal cord injury, motor neuron disease and inform on the potential risk of taking psychoactive drugs during pregnancy. Research programmes at the CNR benefit from close interaction with "Edinburgh Research and Innovation" (ERI) and the Edinburgh BioQuarter, ensuring early identification of commercial potential and support for any patent application or translation. We have a successful track record of working with them. In early 2008, we developed a new method for a multi-stage drug screening method, which, after consultation with ERI's Head of Research and Business Development, Dr Michael Finnen, was filed for patent in the UK on 1. July 2008 and for PCT on 1. July 2009 and has received very favourable reviews. The submission costs were provided by the University after internal review. We will liaise with ERI/BioQuarter in regular intervals to assess any commercial potential of our studies.

Drs Becker are interested in developing industry contacts and have given a presentations on our research at Astra Zeneca's Gothenburg site in 2009 and to Novartis, Genzyme and GSK in 2012. We have a collaboration with Antoxis and GSK using zebrafish for drug screening.

Capability
Many impact activities, described above, have been performed by Drs Catherina and Thomas Becker and they and Dr. Sieger will continue to do so. Moreover, we encourage our post-graduate students to present their data at scientific conferences, but also to engage the public in the various activities that Edinburgh Neuroscience and other organisations run.

There are no cost implications to the BBSRC.