The physiological importance of phospholipase D signalling

Lead Research Organisation: Babraham Institute
Department Name: Deputy Director's Office

Abstract

Hormones, neurotransmitters and growth factors regulate the body s functions by activating processes in cells that produce signals that control the way a cell grows, divides, moves or secretes. One of these signalling pathways involves activation of the enzyme phospholipase D which produces the messenger phosphatidic acid. Studies in cells in tissue culture have suggested that this pathway is activated in many responses and is involved in processes such as how inflammation is activated, how cells move and how they secrete factors. There is a need to understand how these pathways are regulated and the precise roles played by this signalling event, since distortion of the regulation is implicated in inflammatory disorders and other diseases including cancer. The only way to understand this physiological role is to generate and study a genetically modified mouse model. We will isolate cells from the mice and thereby characterise the role and regulation of the signalling. This work has the potential to identify targets for future therapeutic intervention.
The Babraham Institute has an extensive Science and Society programme, involving outreach to local schools and colleges and work with local and national media. In 2007 Babraham won the ?Large Business Award? for its work with schools ? a competition sponsored by the BBC and EU amongst others. All Babraham scientists are actively involved in this programme, with each group leader required to spend 2 days/year on some form of public engagement activity. The Wakelam lab hosts summer and work experience students and assists with other public engagement events as well as being actively involved in visiting primary and secondary schools to attempt to enthuse children about science in general and research in particular, this includes explaining the importance of animal use in research.

Technical Summary

Phospholipase D (PLD) catalyses the hydrolysis of phosphatidylcholine generating phosphatidic acid (PtdOH) as its lipid product. This reaction is stimulated by ligation of receptors for a variety of hormones, neurotransmitter, cytokines and growth factors. PtdOH binds to and activates a number of intracellular targets including phosphatidylinositol-4-phosphate-5-kinase, mTOR, S6kinase, sphingosine kinase1 and the NADPH oxidase. Activation of PLD signalling has been implicated in the regulation of membrane trafficking events, e.g. exocytosis and cytoskeletal events such as adhesion and migration; other reports have suggested roles in regulating glucose transport, superoxide generation, apoptosis, proliferation and differentiation. The two mammalian PLD genes are expressed in all tissues, but their regulation and physiological functions appear to differ. The lack of isoform-specific inhibitors and the limitations of cell line studies have prevented a clear definition of the physiological roles of this ubiquitous signalling pathway. This has pointed to the need to generate genetic models to examine PLD regulation and function. This application builds upon MRC-funded preliminary work that generated a PLD2 knock out mouse that demonstrated effects upon neutrophil responsiveness and brain lipids, in addition defects in ras signaling were detected in derived MEFs . In this programme we will determine the physiological importance of PLD2 by studying the mouse, isolated cells and derived MEFS. The importance of PLD signalling in adhesion, migration and superoxide generation will be examined in isolated neutrophils, whilst mast cells will be used to examine the regulated secretion of inflammatory mediators. By making use of knockouts in other signalling enzymes, particularly PI-3-kinases and PIP-5-kinases to generate double knockouts, we will investigate the regulation and importance of signalling cross talk in physiological regulation. These studies will define the importance of PLD signalling pathways in physiological systems and may point to potential therapeutic targets in inflammatory disorders and other diseases.
 
Description Engagement with House of Commons Science and Technology Committee
Geographic Reach National 
Policy Influence Type Gave evidence to a government review
 
Description Invited lecturer to international meetings (average 2-3 per year) 
Form Of Engagement Activity A talk or presentation
Part Of Official Scheme? No
Geographic Reach International
Primary Audience Professional Practitioners
Results and Impact Generated discussion, exchange of ideas and collaborations
Year(s) Of Engagement Activity Pre-2006,2006,2007,2008,2009,2010,2011,2012,2013,2014,2015,2016,2017,2018,2019
 
Description Schools day 
Form Of Engagement Activity Participation in an open day or visit at my research institution
Part Of Official Scheme? No
Geographic Reach National
Primary Audience Schools
Results and Impact 125 pupils attended schools day, talks given to all and lab practicals ran for two small groups.
Year(s) Of Engagement Activity 2018,2019