Regulation and function of HDAC1 in spinal neuron regeneration in zebrafish

After spinal cord injury, nerve cells in the vicinity of the injury site are destroyed and not replaced. In contrast, in zebrafish, which are capable of full spinal cord regeneration, nerve cells are replaced. The source for new nerve cells are special progenitor cells. These progenitor cells also exist in the spinal cord of mammals, but fail to generate new neurons. We want to understand how progenitor cells in zebrafish can flexibly switch on the production of nerve cells after injury. In preliminary experiments we have identified a DNA-modifying enzyme, called HDAC1, as important. We will manipulate the activity of this enzyme after spinal cord injury in zebrafish using specific drugs and transgenic fish to determine whether HDAC1 is necessary for progenitor cell activity. We will determine how HDAC1 is activated by inflammatory events at the injury site. Then we will identify alterations in gene activity mediated by HDAC1. This will give us important insights into regeneration of new neurons in a vertebrate system. Understanding the important factors in the spinal progenitor cells that allow for neurogenesis in zebrafish may lead to new targets for future therapeutic aiming to harness the endogenous repair capacity of spinal progenitor cells in mammals.

In zebrafish, in contrast to mammals, spinal progenitor cells re-initiate neurogenesis to replace lost neurons. A number of factors, including immune system activation, are known that stimulate the spinal progenitor cells, however, the intrinsic molecular mechanisms in spinal progenitors, the so-called ependymoradial glial cells (ERGs), are poorly understood. Our preliminary results indicate a role for histone deacetylase 1 (HDAC1), shown to be important for developmental neurogenesis, in this process. Here we propose to manipulate HDAC1 activity specifically in ERGs and determine how this will influence regenerative neurogenesis. To this end we will conditionally over-express active and dominant-negative forms of the enzyme specifically in ERGs using the TetON system. These techniques allow us to highly specifically target this cell type. Results will be confirmed by specific pharmacological manipulations of HDAC1 activity. We will also determine regulation of HDAC1 in ERGs by the immune system using gain-and loss of function manipulations, e.g. mutants that are deficient in macrophage development. Furthermore, gene expression changes in FACS purified transgenically-labeled ERGs will be determined by qRT-PCR and expression profiling. This will elucidate specific down-stream pathways of HDAC1 activity. This project will elucidate the function and regulation of HDAC1 for regenerative neurogenesis, providing targets for future therapeutic approaches to mammalian progenitor cells that fail to show regenerative neurogenesis.

The present project aims at finding how the inflammatory response, caused by a spinal lesion is acting on chromatin modification to control spinal neurogenesis. These are fundamental questions in developmental/regenerative biology that could identify potential targets for therapies for motor neuron disease and/spinal cord regeneration. We benefit from close interactions with Edinburgh Research and Innovation (ERI) and Sunergos, the commercial branch of the University, which ensures early identification of commercial potential and support for any patent application or translation. Our current Sunergos liaison Dr Mike Capaldi is aware of our experimental plans. We will liaise with him once a year to assess any commercial potential of the results from this grant.

Our project will comprise aspects of immunology and neuroscience, strengthening scientific collaboration and exchanges with colleagues working in inflammation and repair at the neighbouring Centre for Inflammation Research, in particular Prof Adriano Rossi. We have submitted a project to the WT Tissue Repair programme for a student to work between the Rossi and Becker groups.

We will present our scientific findings at local, regional, national and international meetings of the zebrafish and neuroscience associations (e.g. International Zebrafish Meeting, ISRT, SfN).

Our work will be covered in University press releases, which are leading to media coverage. Press releases are planned for August 2017 to highlight the work in this grant. Further press coverage is planned to accompany publications arising from our work.

The Centre for Neuroregeneration (CNR) is fully committed to increasing public awareness of neuroscience. We sponsor internal and external lecture series including Edinburgh Neuroscience Day, Brain Awareness Week and the Annual Distinguished Lecture, the latter two open to the public. Findings from this grant, in lay language, will be featured on the Centre's and Deanery's web sites.

We regularly participate in public engagement activities, e.g. Centre tours, to explain our science to patients, carers, potential donors and the general public. For example, our postgraduate students have presented our work in the main mall of the New Royal Infirmary (2014/2015), and TB has presented to a Muscular Dystrophy Patient group (2015). We will continue these activities and participate in tours of the Centre explaining our work to the public.

Regeneration research is a particularly attractive topic to engage pupils in science. We will participate in Science and Career Fair activities at local primary and high schools and use work from the current grant to underscore the importance of developmental and regenerative biology and the use of animals in research. For example, TB has presented our work to school pupils (George Watson College, 2016).

The impact activities will be performed by the PIs and our post-graduate students who present their data at conferences, engage the public in science outreach activities, and participate in the annual 3-minute thesis competition, receiving public engagement training through the University and Beltane Network. PI and postgraduate researchers on this grant will present data at the international Zebrafish Meetings (United States 2018, 2020, Europe 2019) and the Network meeting of the International Spinal Research Trust (2019). We will also engage the lay public and scientists at Edinburgh Science Festival Activities.
We plan to provide research and transferable skills training to 2 PhD students and 3 MSc students in the course of this project, building on our significant success in postgraduate training.
There are no resource implications of our above activities for the BBSRC.