Life Sciences Research for Lifelong Health

David Oxley

David obtained a degree in Chemistry from the University of Hull and completed a PhD studying the structures of the O- and K-polysaccharide antigens of the opportunistic pathogen Serratia marcescens. He then moved to the Plant Cell Biology Research Centre at the University of Melbourne in Australia, working first on the structure/function of the S-ribonucleases, the female component of the self-incompatibility system in the many flowering plants; and also on arabinogalactan proteins – ubiquitous plant cell surface and extracellular matrix proteoglycans. After a short spell at Proteome Systems Ltd – a biotech company in Sydney, where he set-up the LC-MS based platform for proteomic analysis and developed high sensitivity LC-MS methods for the analysis of glycoproteins. David joined the Babraham Institute in 2002 and established the Mass Spectrometry Facility, which he still runs.

Latest Publications

Retinol and ascorbate drive erasure of epigenetic memory and enhance reprogramming to naïve pluripotency by complementary mechanisms.
Hore TA, von Meyenn F, Ravichandran M, Bachman M, Ficz G, Oxley D, Santos F, Balasubramanian S, Jurkowski TP, Reik W

Epigenetic memory, in particular DNA methylation, is established during development in differentiating cells and must be erased to create naïve (induced) pluripotent stem cells. The ten-eleven translocation (TET) enzymes can catalyze the oxidation of 5-methylcytosine (5mC) to 5-hydroxymethylcytosine (5hmC) and further oxidized derivatives, thereby actively removing this memory. Nevertheless, the mechanism by which the TET enzymes are regulated, and the extent to which they can be manipulated, are poorly understood. Here we report that retinoic acid (RA) or retinol (vitamin A) and ascorbate (vitamin C) act as modulators of TET levels and activity. RA or retinol enhances 5hmC production in naïve embryonic stem cells by activation of TET2 and TET3 transcription, whereas ascorbate potentiates TET activity and 5hmC production through enhanced Fe(2+) recycling, and not as a cofactor as reported previously. We find that both ascorbate and RA or retinol promote the derivation of induced pluripotent stem cells synergistically and enhance the erasure of epigenetic memory. This mechanistic insight has significance for the development of cell treatments for regenenerative medicine, and enhances our understanding of how intrinsic and extrinsic signals shape the epigenome.

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Proceedings of the National Academy of Sciences of the United States of America, , 1091-6490, , 2016

PMID: 27729528

Exosomes bind autotaxin and act as a physiological delivery mechanism to stimulate LPA receptor signalling in cells.
Jethwa SA, Leah EJ, Zhang Q, Bright NA, Oxley D, Bootman MD, Rudge SA, Wakelam MJ

Autotaxin (ATX) the lysophospholipase responsible for generating the lipid receptor agonist lysophosphatidic acid (LPA) is a secreted enzyme. Here we show that once secreted it can bind to the surface of cell secreted exosomes. Exosome-bound ATX is catalytically active and carries generated LPA. Once bound to a cell, through specific integrin interaction, ATX releases the LPA to activate cell surface G-protein coupled LPA receptors; inhibition of signaling by the receptor antagonist Ki1642 suggests these are either LPAR1 or LPAR3. The binding stimulates downstream signaling including AKT and MAPK phosphorylation, the release of intracellular stored calcium and cell migration. We propose that exosomal binding of LPA-loaded ATX provides a means of efficiently delivering the lipid agonist to cell surface receptors to promote signalling. We further propose that this is a means whereby autotaxin-LPA signaling operates physiologically.

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Journal of cell science, , 1477-9137, , 2016

PMID: 27557622

Norbin Stimulates the Catalytic Activity and Plasma Membrane Localization of the Guanine-Nucleotide Exchange Factor P-Rex1.
Pan D, Barber MA, Hornigold K, Baker MJ, Toth JM, Oxley D, Welch HC

P-Rex1 is a guanine-nucleotide exchange factor (GEF) that activates the small G protein (GTPase) Rac1 to control Rac1-dependent cytoskeletal dynamics, and thus cell morphology. Three mechanisms of P-Rex1 regulation are currently known: (i) binding of the phosphoinositide second messenger PIP3, (ii) binding of the Gβγ subunits of heterotrimeric G proteins, and (iii) phosphorylation of various serine residues. Using recombinant P-Rex1 protein to search for new binding partners, we isolated the G-protein coupled receptor (GPCR)-adaptor protein Norbin (Neurochondrin, NCDN) from mouse brain fractions. Coimmunoprecipitation confirmed the interaction between overexpressed P-Rex1 and Norbin in COS-7 cells, as well as between endogenous P-Rex1 and Norbin in HEK-293 cells. Binding assays with purified recombinant proteins showed that their interaction is direct, and mutational analysis revealed that the PH domain of P-Rex1 is required. Rac-GEF activity assays with purified recombinant proteins showed that direct interaction with Norbin increases the basal, PIP3- and Gβγ-stimulated Rac-GEF activity of P-Rex1. Pak-CRIB pull-down assays demonstrated that Norbin promotes the P-Rex1 mediated activation of endogenous Rac1 upon stimulation of HEK-293 cells with lysophosphatidic acid. Finally, immunofluorescence microscopy and subcellular fractionation showed that coexpression of P-Rex1 and Norbin induces a robust translocation of both proteins from the cytosol to the plasma membrane, as well as promoting cell spreading, lamellipodia formation and membrane ruffling, cell morphologies generated by active Rac1. In summary, we have identified a novel mechanism of P-Rex1 regulation through the GPCR-adaptor protein Norbin, a direct P-Rex1 interacting protein that promotes the Rac-GEF activity and membrane localization of P-Rex1.

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The Journal of biological chemistry, , 1083-351X, , 2016

PMID: 26792863

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Latest Publications

Retinol and ascorbate drive erasure of epigenetic memory and enhance reprogramming to naïve pluripotency by complementary mechanisms.

Hore TA, von Meyenn F, Ravichandran M

Proceedings of the National Academy of Sciences of the United States of America
1091-6490: (2016)

PMID: 27729528

Norbin Stimulates the Catalytic Activity and Plasma Membrane Localization of the Guanine-Nucleotide Exchange Factor P-Rex1.

Pan D, Barber MA, Hornigold K

The Journal of biological chemistry
1083-351X: (2016)

PMID: 26792863

Fgf and Esrrb integrate epigenetic and transcriptional networks that regulate self-renewal of trophoblast stem cells.

Latos PA, Goncalves A, Oxley D

Nature communications
6 2041-1723:7776 (2015)

PMID: 26206133

Resetting transcription factor control circuitry toward ground-state pluripotency in human.

Takashima Y, Guo G, Loos R

Cell
158 1097-4172:1254-69 (2014)

PMID: 25215486

The nuclear exosome is active and important during budding yeast meiosis.

Frenk S, Oxley D, Houseley J

PloS one
9 1932-6203:e107648 (2014)

PMID: 25210768

Dictyostelium uses ether-linked inositol phospholipids for intracellular signalling.

Clark J,Kay RR,Kielkowska A,Niewczas I,Fets L,Oxley D,Stephens LR,Hawkins PT

The EMBO journal
1460-2075: (2014)

PMID: 25180230