Life Sciences Research for Lifelong Health

Publications

The Babraham Institute Publications database contains details of all publications resulting from our research groups and scientific services.

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Title / Authors / Details Open Access Download

SBpipe: a collection of pipelines for automating repetitive simulation and analysis tasks.
Dalle Pezze P, Le Novère N

The rapid growth of the number of mathematical models in Systems Biology fostered the development of many tools to simulate and analyse them. The reliability and precision of these tasks often depend on multiple repetitions and they can be optimised if executed as pipelines. In addition, new formal analyses can be performed on these repeat sequences, revealing important insights about the accuracy of model predictions.

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BMC systems biology, 11, 1752-0509, 46, 2017

PMID: 28395655

Open Access

Dietary restriction protects from age-associated DNA methylation and induces epigenetic reprogramming of lipid metabolism.
Hahn O, Grönke S, Stubbs TM, Ficz G, Hendrich O, Krueger F, Andrews S, Zhang Q, Wakelam MJ, Beyer A, Reik W, Partridge L

Dietary restriction (DR), a reduction in food intake without malnutrition, increases most aspects of health during aging and extends lifespan in diverse species, including rodents. However, the mechanisms by which DR interacts with the aging process to improve health in old age are poorly understood. DNA methylation could play an important role in mediating the effects of DR because it is sensitive to the effects of nutrition and can affect gene expression memory over time.

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Genome biology, 18, 1474-760X, 56, 2017

PMID: 28351387

Open Access

Pharmacological modulators of autophagy activate a parallel noncanonical pathway driving unconventional LC3 lipidation.
Jacquin E, Leclerc-Mercier S, Judon C, Blanchard E, Fraitag S, Florey O

The modulation of canonical macroautophagy/autophagy for therapeutic benefit is an emerging strategy of medical and pharmaceutical interest. Many drugs act to inhibit autophagic flux by targeting lysosome function, while others were developed to activate the pathway. Here, we report the surprising finding that many therapeutically relevant autophagy modulators with lysosomotropic and ionophore properties, classified as inhibitors of canonical autophagy, are also capable of activating a parallel noncanonical autophagy pathway that drives MAP1LC3/LC3 lipidation on endolysosomal membranes. Further, we provide the first evidence supporting drug-induced noncanonical autophagy in vivo using the local anesthetic lidocaine and human skin biopsies. In addition, we find that several published inducers of autophagy and mitophagy are also potent activators of noncanonical autophagy. Together, our data raise important issues regarding the interpretation of LC3 lipidation data and the use of autophagy modulators, and highlight the need for a greater understanding of the functional consequences of noncanonical autophagy.

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Autophagy, , 1554-8635, 1-14, 2017

PMID: 28296541

Class (I) Phosphoinositide 3-Kinases in the Tumor Microenvironment.
Gyori D, Chessa T, Hawkins PT, Stephens LR

Phosphoinositide 3-kinases (PI3Ks) are a diverse family of enzymes which regulate various critical biological processes, such as cell proliferation and survival. Class (I) PI3Ks (PI3Kα, PI3Kβ, PI3Kγ and PI3Kδ) mediate the phosphorylation of the inositol ring at position D3 leading to the generation of PtdIns(3,4,5)P3. PtdIns(3,4,5)P3 can be dephosphorylated by several phosphatases, of which the best known is the 3-phosphatase PTEN (phosphatase and tensin homolog). The Class (I) PI3K pathway is frequently disrupted in human cancers where mutations are associated with increased PI3K-activity or loss of PTEN functionality within the tumor cells. However, the role of PI3Ks in the tumor stroma is less well understood. Recent evidence suggests that the white blood cell-selective PI3Kγ and PI3Kδ isoforms have an important role in regulating the immune-suppressive, tumor-associated myeloid cell and regulatory T cell subsets, respectively, and as a consequence are also critical for solid tumor growth. Moreover, PI3Kα is implicated in the direct regulation of tumor angiogenesis, and dysregulation of the PI3K pathway in stromal fibroblasts can also contribute to cancer progression. Therefore, pharmacological inhibition of the Class (I) PI3K family in the tumor microenvironment can be a highly attractive anti-cancer strategy and isoform-selective PI3K inhibitors may act as potent cancer immunotherapeutic and anti-angiogenic agents.

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Cancers, 9, , , 2017

PMID: 28273837

Open Access

NMN Deamidase Delays Wallerian Degeneration and Rescues Axonal Defects Caused by NMNAT2 Deficiency In Vivo.
Di Stefano M, Loreto A, Orsomando G, Mori V, Zamporlini F, Hulse RP, Webster J, Donaldson LF, Gering M, Raffaelli N, Coleman MP, Gilley J, Conforti L

Axons require the axonal NAD-synthesizing enzyme NMNAT2 to survive. Injury or genetically induced depletion of NMNAT2 triggers axonal degeneration or defective axon growth. We have previously proposed that axonal NMNAT2 primarily promotes axon survival by maintaining low levels of its substrate NMN rather than generating NAD; however, this is still debated. NMN deamidase, a bacterial enzyme, shares NMN-consuming activity with NMNAT2, but not NAD-synthesizing activity, and it delays axon degeneration in primary neuronal cultures. Here we show that NMN deamidase can also delay axon degeneration in zebrafish larvae and in transgenic mice. Like overexpressed NMNATs, NMN deamidase reduces NMN accumulation in injured mouse sciatic nerves and preserves some axons for up to three weeks, even when expressed at a low level. Remarkably, NMN deamidase also rescues axonal outgrowth and perinatal lethality in a dose-dependent manner in mice lacking NMNAT2. These data further support a pro-degenerative effect of accumulating NMN in axons in vivo. The NMN deamidase mouse will be an important tool to further probe the mechanisms underlying Wallerian degeneration and its prevention.

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Current biology : CB, , 1879-0445, , 2017

PMID: 28262487

Open Access

Specifications of Standards in Systems and Synthetic Biology: Status and Developments in 2016.
Schreiber F, Bader GD, Gleeson P, Golebiewski M, Hucka M, Le Novère N, Myers C, Nickerson D, Sommer B, Walthemath D

Standards are essential to the advancement of science and technology. In systems and synthetic biology, numerous standards and associated tools have been developed over the last 16 years. This special issue of the Journal of Integrative Bioinformatics aims to support the exchange, distribution and archiving of these standards, as well as to provide centralised and easily citable access to them.

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Journal of integrative bioinformatics, 13, 1613-4516, 289, 2016

PMID: 28187405

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

Open Access

Assembly of early machinery for autophagy induction: novel insights from high resolution microscopy.
Ktistakis NT, Walker SA, Karanasios E

Oncotarget, , 1949-2553, , 2016

PMID: 27829241

Open Access

Platelets in neutrophil recruitment to sites of inflammation.
Pitchford S, Pan D, Welch HC

This review describes the essential roles of platelets in neutrophil recruitment from the bloodstream into inflamed and infected tissues, with a focus on recent findings.

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Current opinion in hematology, , 1531-7048, , 2016

PMID: 27820736

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

Open Access

Dynamics of mTORC1 activation in response to amino acids.
Manifava M, Smith M, Rotondo S, Walker S, Niewczas I, Zoncu R, Clark J, Ktistakis NT

Amino acids are essential activators of mTORC1 via a complex containing RAG GTPases, RAGULATOR and the vacuolar ATPase. Sensing of amino acids causes translocation of mTORC1 to lysosomes, an obligate step for activation. To examine the spatial and temporal dynamics of this translocation, we used live imaging of the mTORC1 component RAPTOR and a cell permeant fluorescent analogue of di-leucine methyl ester. Translocation to lysosomes is a transient event, occurring within 2 min of aa addition and peaking within 5 min. It is temporally coupled with fluorescent leucine appearance in lysosomes and is sustained in comparison to aa stimulation. Sestrin2 and the vacuolar ATPase are negative and positive regulators of mTORC1 activity in our experimental system. Of note, phosphorylation of canonical mTORC1 targets is delayed compared to lysosomal translocation suggesting a dynamic and transient passage of mTORC1 from the lysosomal surface before targetting its substrates elsewhere.

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eLife, 5, 2050-084X, , 2016

PMID: 27725083

Open Access

The Phospholipase D2 Knock Out Mouse Has Ectopic Purkinje Cells and Suffers from Early Adult-Onset Anosmia.
Vermeren MM, Zhang Q, Smethurst E, Segonds-Pichon A, Schrewe H, Wakelam MJ

Phospholipase D2 (PLD2) is an enzyme that produces phosphatidic acid (PA), a lipid messenger molecule involved in a number of cellular events including, through its membrane curvature properties, endocytosis. The PLD2 knock out (PLD2KO) mouse has been previously reported to be protected from insult in a model of Alzheimer's disease. We have further analysed a PLD2KO mouse using mass spectrophotometry of its lipids and found significant differences in PA species throughout its brain. We have examined the expression pattern of PLD2 which allowed us to define which region of the brain to analyse for defect, notably PLD2 was not detected in glial-rich regions. The expression pattern lead us to specifically examine the mitral cells of olfactory bulbs, the Cornus Amonis (CA) regions of the hippocampus and the Purkinje cells of the cerebellum. We find that the change to longer PA species correlates with subtle architectural defect in the cerebellum, exemplified by ectopic Purkinje cells and an adult-onset deficit of olfaction. These observations draw parallels to defects in the reelin heterozygote as well as the effect of high fat diet on olfaction.

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PloS one, 11, 1932-6203, e0162814, 0

PMID: 27658289

Open Access

Characterization of Atg38 and NRBF2, a fifth subunit of the autophagic Vps34/PIK3C3 complex.
Ohashi Y, Soler N, García Ortegón M, Zhang L, Kirsten ML, Perisic O, Masson GR, Burke JE, Jakobi AJ, Apostolakis AA, Johnson CM, Ohashi M, Ktistakis NT, Sachse C, Williams RL

The phosphatidylinositol 3-kinase Vps34 is part of several protein complexes. The structural organization of heterotetrameric complexes is starting to emerge, but little is known about organization of additional accessory subunits that interact with these assemblies. Combining hydrogen-deuterium exchange mass spectrometry (HDX-MS), X-ray crystallography and electron microscopy (EM), we have characterized Atg38 and its human ortholog NRBF2, accessory components of complex I consisting of Vps15-Vps34-Vps30/Atg6-Atg14 (yeast) and PIK3R4/VPS15-PIK3C3/VPS34-BECN1/Beclin 1-ATG14 (human). HDX-MS shows that Atg38 binds the Vps30-Atg14 subcomplex of complex I, using mainly its N-terminal MIT domain and bridges the coiled-coil I regions of Atg14 and Vps30 in the base of complex I. The Atg38 C-terminal domain is important for localization to the phagophore assembly site (PAS) and homodimerization. Our 2.2 Å resolution crystal structure of the Atg38 C-terminal homodimerization domain shows 2 segments of α-helices assembling into a mushroom-like asymmetric homodimer with a 4-helix cap and a parallel coiled-coil stalk. One Atg38 homodimer engages a single complex I. This is in sharp contrast to human NRBF2, which also forms a homodimer, but this homodimer can bridge 2 complex I assemblies.

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Autophagy, , 1554-8635, 0, 2016

PMID: 27630019

PIKfyve Regulates Vacuole Maturation and Nutrient Recovery following Engulfment.
Krishna S, Palm W, Lee Y, Yang W, Bandyopadhyay U, Xu H, Florey O, Thompson CB, Overholtzer M

The scavenging of extracellular macromolecules by engulfment can sustain cell growth in a nutrient-depleted environment. Engulfed macromolecules are contained within vacuoles that are targeted for lysosome fusion to initiate degradation and nutrient export. We have shown that vacuoles containing engulfed material undergo mTORC1-dependent fission that redistributes degraded cargo back into the endosomal network. Here we identify the lipid kinase PIKfyve as a regulator of an alternative pathway that distributes engulfed contents in support of intracellular macromolecular synthesis during macropinocytosis, entosis, and phagocytosis. We find that PIKfyve regulates vacuole size in part through its downstream effector, the cationic transporter TRPML1. Furthermore, PIKfyve promotes recovery of nutrients from vacuoles, suggesting a potential link between PIKfyve activity and lysosomal nutrient export. During nutrient depletion, PIKfyve activity protects Ras-mutant cells from starvation-induced cell death and supports their proliferation. These data identify PIKfyve as a critical regulator of vacuole maturation and nutrient recovery during engulfment.

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Developmental cell, 38, 1878-1551, 536-47, 2016

PMID: 27623384

The health care and life sciences community profile for dataset descriptions.
Dumontier M, Gray AJ, Marshall MS, Alexiev V, Ansell P, Bader G, Baran J, Bolleman JT, Callahan A, Cruz-Toledo J, Gaudet P, Gombocz EA, Gonzalez-Beltran AN, Groth P, Haendel M, Ito M, Jupp S, Juty N, Katayama T, Kobayashi N, Krishnaswami K, Laibe C, Le Novère N, Lin S, Malone J, Miller M, Mungall CJ, Rietveld L, Wimalaratne SM, Yamaguchi A

Access to consistent, high-quality metadata is critical to finding, understanding, and reusing scientific data. However, while there are many relevant vocabularies for the annotation of a dataset, none sufficiently captures all the necessary metadata. This prevents uniform indexing and querying of dataset repositories. Towards providing a practical guide for producing a high quality description of biomedical datasets, the W3C Semantic Web for Health Care and the Life Sciences Interest Group (HCLSIG) identified Resource Description Framework (RDF) vocabularies that could be used to specify common metadata elements and their value sets. The resulting guideline covers elements of description, identification, attribution, versioning, provenance, and content summarization. This guideline reuses existing vocabularies, and is intended to meet key functional requirements including indexing, discovery, exchange, query, and retrieval of datasets, thereby enabling the publication of FAIR data. The resulting metadata profile is generic and could be used by other domains with an interest in providing machine readable descriptions of versioned datasets.

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PeerJ, 4, 2167-8359, e2331, 2016

PMID: 27602295

Open Access

In B cells, phosphatidylinositol 5-phosphate 4-kinase-α synthesizes PI(4,5)P2 to impact mTORC2 and Akt signaling.
Bulley SJ, Droubi A, Clarke JH, Anderson KE, Stephens LR, Hawkins PT, Irvine RF

Phosphatidylinositol 5-phosphate 4-kinases (PI5P4Ks) are enigmatic lipid kinases with physiological functions that are incompletely understood, not the least because genetic deletion and cell transfection have led to contradictory data. Here, we used the genetic tractability of DT40 cells to create cell lines in which endogenous PI5P4Kα was removed, either stably by genetic deletion or transiently (within 1 h) by tagging the endogenous protein genomically with the auxin degron. In both cases, removal impacted Akt phosphorylation, and by leaving one PI5P4Kα allele present but mutating it to be kinase-dead or have PI4P 5-kinase activity, we show that all of the effects on Akt phosphorylation were dependent on the ability of PI5P4Kα to synthesize phosphatidylinositol (4,5)-bisphosphate [PI(4,5)P2] rather than to remove PI5P. Although stable removal of PI5P4Kα resulted in a pronounced decrease in Akt phosphorylation at Thr308 and Ser473, in part because of reduced plasma membrane PIP3, its acute removal led to an increase in Akt phosphorylation only at Ser473. This process invokes activation primarily of mammalian target of rapamycin complex 2 (mTORC2), which was confirmed by increased phosphorylation of other mTORC2 substrates. These findings establish PI5P4Kα as a kinase that synthesizes a physiologically relevant pool of PI(4,5)P2 and as a regulator of mTORC2, and show a phenomenon similar to the "butterfly effect" described for phosphatidylinositol 3-kinase Iα [Hart JR, et al. (2015) Proc Natl Acad Sci USA 112(4):1131-1136], whereby through apparently the same underlying mechanism, the removal of a protein's activity from a cell can have widely divergent effects depending on the time course of that removal.

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

PMID: 27601656

Open Access

Phosphoproteomic Analyses of Interleukin 2 Signaling Reveal Integrated JAK Kinase-Dependent and -Independent Networks in CD8(+) T Cells.
Ross SH, Rollings C, Anderson KE, Hawkins PT, Stephens LR, Cantrell DA

Interleukin-2 (IL-2) is a fundamental cytokine that controls proliferation and differentiation of T cells. Here, we used high-resolution mass spectrometry to generate a comprehensive and detailed map of IL-2 protein phosphorylations in cytotoxic T cells (CTL). The data revealed that Janus kinases (JAKs) couple IL-2 receptors to the coordinated phosphorylation of transcription factors, regulators of chromatin, mRNA translation, GTPases, vesicle trafficking, and the actin and microtubule cytoskeleton. We identified an IL-2-JAK-independent SRC family Tyr-kinase-controlled signaling network that regulates ∼10% of the CTL phosphoproteome, the production of phosphatidylinositol (3,4,5)-trisphosphate (PIP3), and the activity of the serine/threonine kinase AKT. These data reveal a signaling framework wherein IL-2-JAK-controlled pathways coordinate with IL-2-independent networks of kinase activity and provide a resource toward the further understanding of the networks of protein phosphorylation that program CTL fate.

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Immunity, , 1097-4180, , 2016

PMID: 27566939

Open Access

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

Coincident signals from GPCRs and receptor tyrosine kinases are uniquely transduced by PI3Kβ in myeloid cells.
Houslay DM, Anderson KE, Chessa T, Kulkarni S, Fritsch R, Downward J, Backer JM, Stephens LR, Hawkins PT

Class I phosphoinositide 3-kinases (PI3Ks) catalyze production of the lipid messenger phosphatidylinositol 3,4,5-trisphosphate (PIP3), which plays a central role in a complex signaling network regulating cell growth, survival, and movement. This network is overactivated in cancer and inflammation, and there is interest in determining the PI3K catalytic subunit (p110α, p110β, p110γ, or p110δ) that should be targeted in different therapeutic contexts. Previous studies have defined unique regulatory inputs for p110β, including direct interaction with Gβγ subunits, Rac, and Rab5. We generated mice with knock-in mutations of p110β that selectively blocked the interaction with Gβγ and investigated its contribution to the PI3K isoform dependency of receptor tyrosine kinase (RTK) and G protein (heterotrimeric guanine nucleotide-binding protein)-coupled receptor (GPCR) responses in primary macrophages and neutrophils. We discovered a unique role for p110β in supporting synergistic PIP3 formation in response to the coactivation of macrophages by macrophage colony-stimulating factor (M-CSF) and the complement protein C5a. In contrast, we found partially redundant roles for p110α, p110β, and p110δ downstream of M-CSF alone and a nonredundant role for p110γ downstream of C5a alone. This role for p110β completely depended on direct interaction with Gβγ, suggesting that p110β transduces GPCR signals in the context of coincident activation by an RTK. The p110β-Gβγ interaction was also required for neutrophils to generate reactive oxygen species in response to the Fcγ receptor-dependent recognition of immune complexes and for their β2 integrin-mediated adhesion to fibrinogen or poly-RGD+, directly implicating heterotrimeric G proteins in these two responses.

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Science signaling, 9, 1937-9145, ra82, 2016

PMID: 27531651

Open Access

Autophagy initiation by ULK complex assembly on ER tubulovesicular regions marked by ATG9 vesicles.
Karanasios E, Walker SA, Okkenhaug H, Manifava M, Hummel E, Zimmermann H, Ahmed Q, Domart MC, Collinson L, Ktistakis NT

Autophagosome formation requires sequential translocation of autophagy-specific proteins to membranes enriched in PI3P and connected to the ER. Preceding this, the earliest autophagy-specific structure forming de novo is a small punctum of the ULK1 complex. The provenance of this structure and its mode of formation are unknown. We show that the ULK1 structure emerges from regions, where ATG9 vesicles align with the ER and its formation requires ER exit and coatomer function. Super-resolution microscopy reveals that the ULK1 compartment consists of regularly assembled punctate elements that cluster in progressively larger spherical structures and associates uniquely with the early autophagy machinery. Correlative electron microscopy after live imaging shows tubulovesicular membranes present at the locus of this structure. We propose that the nucleation of autophagosomes occurs in regions, where the ULK1 complex coalesces with ER and the ATG9 compartment.

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Nature communications, 7, 2041-1723, 12420, 2016

PMID: 27510922

Open Access

C13orf31 (FAMIN) is a central regulator of immunometabolic function.
Cader MZ, Boroviak K, Zhang Q, Assadi G, Kempster SL, Sewell GW, Saveljeva S, Ashcroft JW, Clare S, Mukhopadhyay S, Brown KP, Tschurtschenthaler M, Raine T, Doe B, Chilvers ER, Griffin JL, Kaneider NC, Floto RA, D'Amato M, Bradley A, Wakelam MJ, Dougan G, Kaser A

Single-nucleotide variations in C13orf31 (LACC1) that encode p.C284R and p.I254V in a protein of unknown function (called 'FAMIN' here) are associated with increased risk for systemic juvenile idiopathic arthritis, leprosy and Crohn's disease. Here we set out to identify the biological mechanism affected by these coding variations. FAMIN formed a complex with fatty acid synthase (FASN) on peroxisomes and promoted flux through de novo lipogenesis to concomitantly drive high levels of fatty-acid oxidation (FAO) and glycolysis and, consequently, ATP regeneration. FAMIN-dependent FAO controlled inflammasome activation, mitochondrial and NADPH-oxidase-dependent production of reactive oxygen species (ROS), and the bactericidal activity of macrophages. As p.I254V and p.C284R resulted in diminished function and loss of function, respectively, FAMIN determined resilience to endotoxin shock. Thus, we have identified a central regulator of the metabolic function and bioenergetic state of macrophages that is under evolutionary selection and determines the risk of inflammatory and infectious disease.

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Nature immunology, , 1529-2916, , 2016

PMID: 27478939

3D correlative light and electron microscopy of cultured cells using serial blockface scanning electron microscopy.
Russell MR, Lerner TR, Burden JJ, Nkwe DO, Pelchen-Matthews A, Domart MC, Durgan J, Weston A, Jones ML, Peddie CJ, Carzaniga R, Florey O, Marsh M, Gutierrez MG, Collinson LM

The processes of life take place in multiple dimensions, but imaging these processes in even three dimensions is challenging. Here we describe a workflow for 3D correlative light and electron microscopy (CLEM) of cell monolayers using fluorescence microscopy to identify and follow biological events, combined with serial blockface scanning electron microscopy to analyse the underlying ultrastructure. The workflow encompasses all steps from cell culture to sample processing, imaging strategy and 3D image processing/analysis. We demonstrate successful application of the workflow to three studies, each aiming to better understand complex and dynamic biological processes, including bacterial and viral infections of cultured cells and formation of entotic cell-in-cell structures commonly observed in tumours. Our workflow revealed new insight into the replicative niche of Mycobacterium tuberculosis in primary human lymphatic endothelial cells, HIV-1 in human monocyte-derived macrophages, and the composition of the entotic vacuole. The broad application of this 3D CLEM technique will make it a useful addition to the correlative imaging toolbox for biomedical research.

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

PMID: 27445312

Open Access

Synaptophysin depletion and intraneuronal Aβ in organotypic hippocampal slice cultures from huAPP transgenic mice.
Harwell CS, Coleman MP

To date, there are no effective disease-modifying treatments for Alzheimer's disease (AD). In order to develop new therapeutics for stages where they are most likely to be effective, it is important to identify the first pathological alterations in the disease cascade. Changes in Aβ concentration have long been reported as one of the first steps, but understanding the source, and earliest consequences, of pathology requires a model system that represents all major CNS cell types, is amenable to repeated observation and sampling, and can be readily manipulated. In this regard, long term organotypic hippocampal slice cultures (OHSCs) from neonatal amyloid mice offer an excellent compromise between in vivo and primary culture studies, largely retaining the cellular composition and neuronal architecture of the in vivo hippocampus, but with the in vitro advantages of accessibility to live imaging, sampling and intervention.

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Molecular neurodegeneration, 11, 1750-1326, 44, 2016

PMID: 27287430

Application of virtual screening to the discovery of novel nicotinamide phosphoribosyltransferase (NAMPT) inhibitors with potential for the treatment of cancer and axonopathies.
Clark DE, Waszkowycz B, Wong M, Lockey PM, Adalbert R, Gilley J, Clark J, Coleman MP

NAMPT may represent a novel target for drug discovery in various therapeutic areas, including oncology and inflammation. Additionally, recent work has suggested that targeting NAMPT has potential in treating axon degeneration. In this work, publicly available X-ray co-crystal structures of NAMPT and the structures of two known NAMPT inhibitors were used as the basis for a structure- and ligand-based virtual screening campaign. From this, two novel series of NAMPT inhibitors were identified, one of which showed a statistically significant protective effect when tested in a cellular model of axon degeneration.

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Bioorganic & medicinal chemistry letters, , 1464-3405, , 2016

PMID: 27158141

Open Access