Award details

Function of a Drosophila DAG lapase in nervous system development

Reference	BB/D523427/1
Principal Investigator / Supervisor	Professor Patrick Doherty
Co-Investigators / Co-Supervisors	Dr Susana Romani-Paez
Institution	King's College London
Department	Wolfson Centre for Age Related Diseases
Funding type	Research
Value (£)	308,245
Status	Completed
Type	Research Grant
Start date	01/01/2006
End date	31/12/2008
Duration	36 months

Abstract

This project is aimed to understand the role of DAG Lipase (DAGL), a key enzyme that hydrolises diacylglycerol (DAG) to 2-arachidonylglycerol (2-AG). DAG is an essential lipid-derived second messenger that drives a wide variety of cellular responses and its activity can be limited by DAGL. DAGL activity also controls the synthesis of a number of other lipid-derived second messengers such as 2-arachidonylglyceroll (2-AG), which in vertebrates can serve as a ligand for the CB1 cannabinoid receptor. However, 2-AG can also serve as a precursor for other second messengers including arachidonic acid and the glycerol esters of the prostaglandins. Thus DAG Lipase can control a multitude of different processes. DAGL became important for us as a direct consequence of our work on cell adhesion molecule (CAM) signalling; we have established that CAMs promote axonal growth by activating FGF receptors in neurons, and that DAGL activity couples CAM and FGF responses to axonal growth. Since then other groups have corroborated and extended our observations. We have cloned two human DAG Lipase but studies in vivo are very complicated in vertebrates and impossible in humans. We decided to use the fruit fly Drosophila melanogaster as a tool to analyse the function of this enzyme in the context of CAM-FGFr signalling in the nervous system. After cloning the enzyme and producing basic tools such as antibodies and mutations in the gene we propose to characterise the gene genetically, molecularly and functionally with respect to its function in axonal growth and guidance both in the whole fly and in an in vitro neuronal culture assay. We also anticipate that the fly will be useful for structure-function studies aimed at making drugs to modulate the activity of the enzymes.

Summary

Second messengers play an essential role in allowing cells to respond to their environment and communicate with each other. Diacyglycerol (DAG) is one of the essential second messengers that is made from lipids in the membrane in response to signals from the outside of the cell. It controls many cellular functions such as proliferation (how many cells we make) differentiation (what the cell becomes). As the second messengers are very powerful (e.g. too much could give you a cancer), it is very important to make them and destroy them in a highly regulated manner. The action of DAG can be terminated by an enzyme called DAG lipase, and this not only stops DAG signalling, it also generates a whole new family of second messengers. One of these is a molecule that activates cannabinoid receptors in the brain. DAG lipase activity is required for neurons to extend axons, and is likely to play a role in processes required for the development and repair of the brain. DAG lipase activity is also required in order to allow synapses in the adult brain to function properly by controlling cannabinoid signalling, and this has been shown to be important for many things including the control of pain. In fact, it has been suggested that the cannabinoid pathway might be modulated for therapeutic benefit for a wide range of conditions such as pain, obesity, spastic disorders, epilepsy, various psychiatric conditions. My group has recently cloned the DAG lipases that are present in man, and found interesting patterns of expression that are in keeping with what was predicted about where they need to be to do their job. However, to fully understand what they do, we need to make animals that do not have the enzymes; we can determine what this does to the development of the brain and also use the animals as a model for introducing mutated forms of the enzymes back to identify the important bits that allow the enzymes to do their jobs. To do this in mice might kill them, and even if it did notit would be time consuming and expensive, with results complicated by the fact that there are two enzymes that pretty much to the same job and we would need to get rid of both. However, the fruit fly has a single enzyme that is also present in the nervous system, this provides a faster, simpler and reliable way to gain insight into biological processes that are common to most living organisms including the fly and man (we both need a nervous system, and they develop in similar ways). If we can understand what the enzymes do, and find out which parts of the enzymes are important, we can think about making drugs that will help with pain and a number of brain diseases.

Committee	Closed Committee - Genes & Developmental Biology (GDB)
Research Topics	Neuroscience and Behaviour, The 3 Rs (Replacement, Reduction and Refinement of animals in research)
Research Priority	X – Research Priority information not available
Research Initiative	X - not in an Initiative
Funding Scheme	X – not Funded via a specific Funding Scheme

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