Life Sciences Research for Lifelong Health

Michael Wakelam

Research Summary

We aim to understand the essential physiological functions of lipids. Lipids are highly dynamic structures with structural, metabolic and signalling roles. To fully understand the roles that lipids have in cell function during ageing we need the ability to determine their individual changes.

The cellular lipidome is extremely complex, with distinct classes of lipids each containing many molecular species that can differ both in the length of each acyl chain present and in the number and position of double bonds.

In our lab we have pioneered the use of high-sensitivity liquid chromatography-mass spectrometry (LC-MS) technology to rapidly and comprehensively measure the levels of lipids in a wide range of cell types, tissues and tumours. The lipidome of a cell typically comprises of ~ 1500 distinct lipid species measurable with current LC-MS technology. However, this number is most likely an underestimate since there are theoretically closer to 10 000 distinct lipid species in the lipidome.

The principal aim of our laboratory is to better understand how the distinct lipid species of a cell’s lipidome function during the healthy ageing of the whole animal.

​To achieve this we use a multidisciplinary approach combining LC-MS analysis, protein biochemistry, cell biology and genetic manipulation of model organisms. This allows us to identify the cellular signalling pathways and processes that individual lipid species regulate, and to investigate how the enzymes that determine the composition of the lipidome are regulated in response to changes in the environment.

Latest Publications

Autotaxin-lysophosphatidic acid receptor signalling regulates hepatitis C virus replication.
Farquhar MJ, Humphreys IS, Rudge SA, Wilson GK, Bhattacharya B, Ciaccia M, Hu K, Zhang Q, Mailly L, Reynolds GM, Aschcroft M, Balfe P, Baumert TF, Roessler S, Wakelam MJ, McKeating JA

Chronic hepatitis C is a global health problem with an estimated 170 million HCV infected individuals at risk of progressive liver disease and hepatocellular carcinoma (HCC). Autotaxin (ATX) is a phospholipase with diverse roles in physiological and pathological processes including inflammation and oncogenesis. Clinical studies have reported increased ATX expression in chronic hepatitis C, however, the pathways regulating ATX and its role in the viral life cycle are not well understood.

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Journal of hepatology, , 1600-0641, , 2017

PMID: 28126468

Phospholipase D activity couples plasma membrane endocytosis with retromer dependent recycling.
Thakur R, Panda A, Coessens E, Raj N, Yadav S, Balakrishnan S, Zhang Q, Georgiev P, Basak B, Pasricha R, Wakelam MJ, Ktistakis NT, Padinjat R

During illumination, the light sensitive plasma membrane (rhabdomere) of Drosophila photoreceptors undergoes turnover with consequent changes in size and composition. However the mechanism by which illumination is coupled to rhabdomere turnover remains unclear. We find that photoreceptors contain a light-dependent phospholipase D (PLD) activity. During illumination, loss of PLD resulted in an enhanced reduction in rhabdomere size, accumulation of Rab7 positive, rhodopsin1-containing vesicles (RLVs) in the cell body and reduced rhodopsin protein. These phenotypes were associated with reduced levels of phosphatidic acid, the product of PLD activity and were rescued by reconstitution with catalytically active PLD. In wild type photoreceptors, during illumination, enhanced PLD activity was sufficient to clear RLVs from the cell body by a process dependent on Arf1-GTP levels and retromer complex function. Thus, during illumination, PLD activity couples endocytosis of RLVs with their recycling to the plasma membrane thus maintaining plasma membrane size and composition.

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eLife, 5, 2050-084X, , 2016

PMID: 27848911

Insulin resistance uncoupled from dyslipidemia due to C-terminal PIK3R1 mutations.
Huang-Doran I, Tomlinson P, Payne F, Gast A, Sleigh A, Bottomley W, Harris J, Daly A, Rocha N, Rudge S, Clark J, Kwok A, Romeo S, McCann E, Müksch B, Dattani M, Zucchini S, Wakelam M, Foukas LC, Savage DB, Murphy R, O'Rahilly S, Barroso I, Semple RK

Obesity-related insulin resistance is associated with fatty liver, dyslipidemia, and low plasma adiponectin. Insulin resistance due to insulin receptor (INSR) dysfunction is associated with none of these, but when due to dysfunction of the downstream kinase AKT2 phenocopies obesity-related insulin resistance. We report 5 patients with SHORT syndrome and C-terminal mutations in PIK3R1, encoding the p85α/p55α/p50α subunits of PI3K, which act between INSR and AKT in insulin signaling. Four of 5 patients had extreme insulin resistance without dyslipidemia or hepatic steatosis. In 3 of these 4, plasma adiponectin was preserved, as in insulin receptor dysfunction. The fourth patient and her healthy mother had low plasma adiponectin associated with a potentially novel mutation, p.Asp231Ala, in adiponectin itself. Cells studied from one patient with the p.Tyr657X PIK3R1 mutation expressed abundant truncated PIK3R1 products and showed severely reduced insulin-stimulated association of mutant but not WT p85α with IRS1, but normal downstream signaling. In 3T3-L1 preadipocytes, mutant p85α overexpression attenuated insulin-induced AKT phosphorylation and adipocyte differentiation. Thus, PIK3R1 C-terminal mutations impair insulin signaling only in some cellular contexts and produce a subphenotype of insulin resistance resembling INSR dysfunction but unlike AKT2 dysfunction, implicating PI3K in the pathogenesis of key components of the metabolic syndrome.

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JCI insight, 1, , e88766, 2016

PMID: 27766312

 

Group Members

Latest Publications

Autotaxin-lysophosphatidic acid receptor signalling regulates hepatitis C virus replication.

Farquhar MJ, Humphreys IS, Rudge SA

Journal of hepatology
1600-0641: (2017)

PMID: 28126468

Insulin resistance uncoupled from dyslipidemia due to C-terminal PIK3R1 mutations.

Huang-Doran I, Tomlinson P, Payne F

JCI insight
1 :e88766 (2016)

PMID: 27766312

The Phospholipase D2 Knock Out Mouse Has Ectopic Purkinje Cells and Suffers from Early Adult-Onset Anosmia.

Vermeren MM, Zhang Q, Smethurst E

PloS one
11 1932-6203:e0162814 (0)

PMID: 27658289

C13orf31 (FAMIN) is a central regulator of immunometabolic function.

Cader MZ, Boroviak K, Zhang Q

Nature immunology
1529-2916: (2016)

PMID: 27478939

Purification, characterization and crystallization of the F-ATPase from Paracoccus denitrificans.

Morales-Rios E, Watt IN, Zhang Q

Open biology
5 2046-2441: (2015)

PMID: 26423580

Phosphoinositide 3-kinase-related overgrowth: cellular phenotype and future therapeutic options.

Parker VE, Knox RG, Zhang Q

Lancet (London, England)
385 Suppl 1 1474-547X:S77 (2015)

PMID: 26312899

Phosphatidylinositolphosphate Phosphatase Activities and Cancer.

Rudge SA, Wakelam MJ

Journal of lipid research
0022-2275: (2015)

PMID: 26302980

Speed and sensitivity of phototransduction in Drosophila depend on degree of saturation of membrane phospholipids.

Randall AS, Liu CH, Chu B

The Journal of neuroscience : the official journal of the Society for Neuroscience
35 1529-2401:2731-46 (2015)

PMID: 25673862