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1.  Retracted manuscript 
Small GTPases  2013;4(2):61.
The following article from Small GTPases, “Scientific Yellow Journalism” by Anica Klockars and Michael J. Williams, published online on 20 September 2012  (doi: 10.4161/sgtp.22289; by Landes Bioscience and subsequently published in print in Small GTPases 2012 3(4):201 has been retracted by agreement between the authors and the journal’s Editor in Chief, Michael J. Williams (also an author of the paper). 
PMCID: PMC3747257  PMID: 23485921
2.  Lipoprotein (a) upregulates ABCA1 in liver cells via scavenger receptor-B1 through its oxidized phospholipids[S] 
Journal of Lipid Research  2015;56(7):1318-1328.
Elevated levels of lipoprotein (a) [Lp(a)] are a well-established risk factor for developing CVD. While Lp(a) levels are thought to be independent of other plasma lipoproteins, some trials have reported a positive association between Lp(a) and HDL. Whether Lp(a) has a direct effect on HDL is not known. Here we investigated to determine whether Lp(a) had any effect on the ABCA1 pathway of HDL production in liver cells. Incubation of HepG2 cells with Lp(a) upregulated the PPARγ protein by 1.7-fold and the liver X receptor α protein by 3-fold. This was accompanied by a 1.8-fold increase in ABCA1 protein and a 1.5-fold increase in cholesterol efflux onto apoA1. We showed that Lp(a) was internalized by HepG2 cells, however, the ABCA1 response to Lp(a) was mediated by the selective uptake of oxidized phospholipids (oxPLs) from Lp(a) via the scavenger receptor-B1 and not by Lp(a) internalization per se. We conclude that there is a biological connection between Lp(a) and HDL through the ability of Lp(a)’s oxPLs to upregulate HDL biosynthesis.
PMCID: PMC4479336  PMID: 25852127
adenosine 5′-triphosphate binding cassette transporter A1; cholesterol efflux; high density lipoprotein; nuclear receptor/liver X receptor; nuclear receptor/peroxisome proliferator-activated receptor
3.  Implication of coronin 7 in body weight regulation in humans, mice and flies 
BMC Neuroscience  2015;16:13.
Obesity is a growing global concern with strong associations with cardiovascular disease, cancer and type-2 diabetes. Although various genome-wide association studies have identified more than 40 genes associated with obesity, these genes cannot fully explain the heritability of obesity, suggesting there may be other contributing factors, including epigenetic effects.
We performed genome wide DNA methylation profiling comparing normal-weight and obese 9–13 year old children to investigate possible epigenetic changes correlated with obesity. Of note, obese children had significantly lower methylation levels at a CpG site located near coronin 7 (CORO7), which encodes a tryptophan-aspartic acid dipeptide (WD)-repeat containing protein most likely involved in Golgi complex morphology and function. Anatomical profiling of coronin 7 (Coro7) mRNA expression in mice revealed that it is highly expressed in appetite and energy balance regulating regions, including the hypothalamus, striatum and locus coeruleus, the main noradrenergic brain site. Interestingly, we found that food deprivation in mice downregulates hypothalamic Coro7 mRNA levels, and injecting ethanol, an appetite stimulant, increased the number of Coro7 expressing cells in the locus coeruleus. Finally, by employing the genetically-tractable Drosophila melanogaster model we were able to demonstrate an evolutionarily conserved metabolic function for the CORO7 homologue pod1. Knocking down the pod1 in the Drosophila adult nervous system increased their resistance to starvation. Furthermore, feeding flies a high-calorie diet significantly increased pod1 expression.
We conclude that coronin 7 is involved in the regulation of energy homeostasis and this role stems, to some degree, from the effect on feeding for calories and reward.
PMCID: PMC4364644  PMID: 25887538
Coronin 7; Obesity; Homeostatic control; Gene expression
4.  The GPCR repertoire in the demosponge Amphimedon queenslandica: insights into the GPCR system at the early divergence of animals 
G protein-coupled receptors (GPCRs) play a central role in eukaryotic signal transduction. However, the GPCR component of this signalling system, at the early origins of metazoans is not fully understood. Here we aim to identify and classify GPCRs in Amphimedon queenslandica (sponge), a member of an earliest diverging metazoan lineage (Porifera). Furthermore, phylogenetic comparisons of sponge GPCRs with eumetazoan and bilaterian GPCRs will be essential to our understanding of the GPCR system at the roots of metazoan evolution.
We present a curated list of 220 GPCRs in the sponge genome after excluding incomplete sequences and false positives from our initial dataset of 282 predicted GPCR sequences obtained using Pfam search. Phylogenetic analysis reveals that the sponge genome contains members belonging to four of the five major GRAFS families including Glutamate (33), Rhodopsin (126), Adhesion (40) and Frizzled (3). Interestingly, the sponge Rhodopsin family sequences lack orthologous relationships with those found in eumetazoan and bilaterian lineages, since they clustered separately to form sponge specific groups in the phylogenetic analysis. This suggests that sponge Rhodopsins diverged considerably from that found in other basal metazoans. A few sponge Adhesions clustered basal to Adhesion subfamilies commonly found in most vertebrates, suggesting some Adhesion subfamilies may have diverged prior to the emergence of Bilateria. Furthermore, at least eight of the sponge Adhesion members have a hormone binding motif (HRM domain) in their N-termini, although hormones have yet to be identified in sponges. We also phylogenetically clarified that sponge has homologs of metabotropic glutamate (mGluRs) and GABA receptors.
Our phylogenetic comparisons of sponge GPCRs with other metazoan genomes suggest that sponge contains a significantly diversified set of GPCRs. This is evident at the family/subfamily level comparisons for most GPCR families, in particular for the Rhodopsin family of GPCRs. In summary, this study provides a framework to perform future experimental and comparative studies to further verify and understand the roles of GPCRs that predates the divergence of bilaterian and eumetazoan lineages.
Electronic supplementary material
The online version of this article (doi:10.1186/s12862-014-0270-4) contains supplementary material, which is available to authorized users.
PMCID: PMC4302439  PMID: 25528161
Neurotransmitters; G protein-coupled receptors; Adhesion; Signal transduction; Porifera; Eumetazoa
5.  Introduction to Small GTPases 
Small GTPases  2010;1(1):1.
PMCID: PMC3109482  PMID: 21686116
6.  Genome-wide association study identifies a sequence variant within the DAB2IP gene conferring susceptibility to abdominal aortic aneurysm 
Gretarsdottir, Solveig | Baas, Annette F | Thorleifsson, Gudmar | Holm, Hilma | den Heijer, Martin | de Vries, Jean-Paul P M | Kranendonk, Steef E | Zeebregts, Clark J A M | van Sterkenburg, Steven M | Geelkerken, Robert H | van Rij, Andre M | Williams, Michael J A | Boll, Albert P M | Kostic, Jelena P | Jonasdottir, Adalbjorg | Jonasdottir, Aslaug | Walters, G Bragi | Masson, Gisli | Sulem, Patrick | Saemundsdottir, Jona | Mouy, Magali | Magnusson, Kristinn P | Tromp, Gerard | Elmore, James R | Sakalihasan, Natzi | Limet, Raymond | Defraigne, Jean-Olivier | Ferrell, Robert E | Ronkainen, Antti | Ruigrok, Ynte M | Wijmenga, Cisca | Grobbee, Diederick E | Shah, Svati H | Granger, Christopher B | Quyyumi, Arshed A | Vaccarino, Viola | Patel, Riyaz S | Zafari, A Maziar | Levey, Allan I | Austin, Harland | Girelli, Domenico | Pignatti, Pier Franco | Olivieri, Oliviero | Martinelli, Nicola | Malerba, Giovanni | Trabetti, Elisabetta | Becker, Lewis C | Becker, Diane M | Reilly, Muredach P | Rader, Daniel J | Mueller, Thomas | Dieplinger, Benjamin | Haltmayer, Meinhard | Urbonavicius, Sigitas | Lindblad, Bengt | Gottsäter, Anders | Gaetani, Eleonora | Pola, Roberto | Wells, Philip | Rodger, Marc | Forgie, Melissa | Langlois, Nicole | Corral, Javier | Vicente, Vicente | Fontcuberta, Jordi | España, Francisco | Grarup, Niels | Jørgensen, Torben | Witte, Daniel R | Hansen, Torben | Pedersen, Oluf | Aben, Katja K | de Graaf, Jacqueline | Holewijn, Suzanne | Folkersen, Lasse | Franco-Cereceda, Anders | Eriksson, Per | Collier, David A | Stefansson, Hreinn | Steinthorsdottir, Valgerdur | Rafnar, Thorunn | Valdimarsson, Einar M | Magnadottir, Hulda B | Sveinbjornsdottir, Sigurlaug | Olafsson, Isleifur | Magnusson, Magnus Karl | Palmason, Robert | Haraldsdottir, Vilhelmina | Andersen, Karl | Onundarson, Pall T | Thorgeirsson, Gudmundur | Kiemeney, Lambertus A | Powell, Janet T | Carey, David J | Kuivaniemi, Helena | Lindholt, Jes S | Jones, Gregory T | Kong, Augustine | Blankensteijn, Jan D | Matthiasson, Stefan E | Thorsteinsdottir, Unnur | Stefansson, Kari
Nature genetics  2010;42(8):692-697.
We performed a genome-wide association study on 1,292 individuals with abdominal aortic aneurysms (AAAs) and 30,503 controls from Iceland and The Netherlands, with a follow-up of top markers in up to 3,267 individuals with AAAs and 7,451 controls. The A allele of rs7025486 on 9q33 was found to associate with AAA, with an odds ratio (OR) of 1.21 and P = 4.6 × 10−10. In tests for association with other vascular diseases, we found that rs7025486[A] is associated with early onset myocardial infarction (OR = 1.18, P = 3.1 × 10−5), peripheral arterial disease (OR = 1.14, P = 3.9 × 10−5) and pulmonary embolism (OR = 1.20, P = 0.00030), but not with intracranial aneurysm or ischemic stroke. No association was observed between rs7025486[A] and common risk factors for arterial and venous diseases—that is, smoking, lipid levels, obesity, type 2 diabetes and hypertension. Rs7025486 is located within DAB2IP, which encodes an inhibitor of cell growth and survival.
PMCID: PMC4157066  PMID: 20622881
7.  Obesity-Linked Homologues TfAP-2 and Twz Establish Meal Frequency in Drosophila melanogaster 
PLoS Genetics  2014;10(9):e1004499.
In all animals managing the size of individual meals and frequency of feeding is crucial for metabolic homeostasis. In the current study we demonstrate that the noradrenalin analogue octopamine and the cholecystokinin (CCK) homologue Drosulfakinin (Dsk) function downstream of TfAP-2 and Tiwaz (Twz) to control the number of meals in adult flies. Loss of TfAP-2 or Twz in octopaminergic neurons increased the size of individual meals, while overexpression of TfAP-2 significantly decreased meal size and increased feeding frequency. Of note, our study reveals that TfAP-2 and Twz regulate octopamine signaling to initiate feeding; then octopamine, in a negative feedback loop, induces expression of Dsk to inhibit consummatory behavior. Intriguingly, we found that the mouse TfAP-2 and Twz homologues, AP-2β and Kctd15, co-localize in areas of the brain known to regulate feeding behavior and reward, and a proximity ligation assay (PLA) demonstrated that AP-2β and Kctd15 interact directly in a mouse hypothalamus-derived cell line. Finally, we show that in this mouse hypothalamic cell line AP-2β and Kctd15 directly interact with Ube2i, a mouse sumoylation enzyme, and that AP-2β may itself be sumoylated. Our study reveals how two obesity-linked homologues regulate metabolic homeostasis by modulating consummatory behavior.
Author Summary
The size of individual meals and feeding frequency are important for homeostatic control. Due to the complex neuroendocrine system regulating human food intake it is difficult to uncover the mechanisms underlying eating disorders. The genetically tractable model system Drosophila melanogaster has a comparatively simple brain; yet, similar to humans, its eating behavior can adapt to respond to nutritional needs. Our study describes how the obesity-linked homologues TfAP-2 (human TFAP2B) and Tiwaz (human KCTD15) regulate a unique feedback system involving noradrenalin-like octopamine and the CCK homolog Dsk, that exert positive and negative effects on Drosophila feeding behavior. Our findings provide insight into how two conserved obesity-linked genes regulate feeding behavior in order to maintain metabolic balance.
PMCID: PMC4154645  PMID: 25187989
8.  A sequence variant associated with sortilin-1 (SORT1) on 1p13.3 is independently associated with abdominal aortic aneurysm 
Human Molecular Genetics  2013;22(14):2941-2947.
Abdominal aortic aneurysm (AAA) is a common human disease with a high estimated heritability (0.7); however, only a small number of associated genetic loci have been reported to date. In contrast, over 100 loci have now been reproducibly associated with either blood lipid profile and/or coronary artery disease (CAD) (both risk factors for AAA) in large-scale meta-analyses. This study employed a staged design to investigate whether the loci for these two phenotypes are also associated with AAA. Validated CAD and dyslipidaemia loci underwent screening using the Otago AAA genome-wide association data set. Putative associations underwent staged secondary validation in 10 additional cohorts. A novel association between the SORT1 (1p13.3) locus and AAA was identified. The rs599839 G allele, which has been previously associated with both dyslipidaemia and CAD, reached genome-wide significance in 11 combined independent cohorts (meta-analysis with 7048 AAA cases and 75 976 controls: G allele OR 0.81, 95% CI 0.76–0.85, P = 7.2 × 10−14). Modelling for confounding interactions of concurrent dyslipidaemia, heart disease and other risk factors suggested that this marker is an independent predictor of AAA susceptibility. In conclusion, a genetic marker associated with cardiovascular risk factors, and in particular concurrent vascular disease, appeared to independently contribute to susceptibility for AAA. Given the potential genetic overlap between risk factor and disease phenotypes, the use of well-characterized case–control cohorts allowing for modelling of cardiovascular disease risk confounders will be an important component in the future discovery of genetic markers for conditions such as AAA.
PMCID: PMC3690970  PMID: 23535823
9.  Drosophila Insulin-Producing Cells Are Differentially Modulated by Serotonin and Octopamine Receptors and Affect Social Behavior 
PLoS ONE  2014;9(6):e99732.
A set of 14 insulin-producing cells (IPCs) in the Drosophila brain produces three insulin-like peptides (DILP2, 3 and 5). Activity in IPCs and release of DILPs is nutrient dependent and controlled by multiple factors such as fat body-derived proteins, neurotransmitters, and neuropeptides. Two monoamine receptors, the octopamine receptor OAMB and the serotonin receptor 5-HT1A, are expressed by the IPCs. These receptors may act antagonistically on adenylate cyclase. Here we investigate the action of the two receptors on activity in and output from the IPCs. Knockdown of OAMB by targeted RNAi led to elevated Dilp3 transcript levels in the brain, whereas 5-HT1A knockdown resulted in increases of Dilp2 and 5. OAMB-RNAi in IPCs leads to extended survival of starved flies and increased food intake, whereas 5-HT1A-RNAi produces the opposite phenotypes. However, knockdown of either OAMB or 5-HT1A in IPCs both lead to increased resistance to oxidative stress. In assays of carbohydrate levels we found that 5-HT1A knockdown in IPCs resulted in elevated hemolymph glucose, body glycogen and body trehalose levels, while no effects were seen after OAMB knockdown. We also found that manipulations of the two receptors in IPCs affected male aggressive behavior in different ways and 5-HT1A-RNAi reduced courtship latency. Our observations suggest that activation of 5-HT1A and OAMB signaling in IPCs generates differential effects on Dilp transcription, fly physiology, metabolism and social interactions. However the findings do not support an antagonistic action of the two monoamines and their receptors in this particular system.
PMCID: PMC4055686  PMID: 24923784
10.  Cerebral blood flow and cerebrovascular reactivity at rest and during sub-maximal exercise: Effect of age and 12-week exercise training 
Age  2012;35(3):905-920.
Chronic reductions in cerebral blood flow (CBF) and cerebrovascular reactivity to CO2 are risk factors for cerebrovascular disease. Higher aerobic fitness is associated with higher CBF at any age; however, whether CBF or reactivity can be elevated following an exercise training intervention in healthy individuals is unknown. The aim of this study was to assess the effect of exercise training on CBF and cerebrovascular reactivity at rest and during exercise in young and older individuals. Ten young (23 ± 5 years; body mass index (BMI), 26 ± 3 kg m−2; \documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$ {\mathop{V}\limits^{ \cdot }{_{\text{O2}}}}\max $$\end{document}, 35 ± 5 ml kg−1 min−1) and 10 older (63 ± 5 years; BMI, 25 ± 3.0 kg m−2; \documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$ {\mathop{V}\limits^{ \cdot }{_{\text{O2}}}}\max $$\end{document}, 26 ± 4 ml kg-1 min−1) previously sedentary individuals breathed 5 % CO2 for 3 min at rest and during steady-state cycling exercise (30 and 70 % heart rate range (HRR)) prior to and following a 12-week aerobic exercise intervention. Effects of training on middle cerebral artery blood velocity (MCAv) at rest were unclear in both age groups. The absolute MCAv response to exercise was greater in the young (9 and 9 cm s−1 (30 and 70 % HRR, respectively) vs. 5 and 4 cm s−1 (older), P < 0.05) and was similar following training. Cerebrovascular reactivity was elevated following the 12-week training at rest (2.87 ± 0.76 vs. 2.54 ± 1.12 cm s−1 mm Hg−1, P = 0.01) and during exercise, irrespective of age. The finding of a training-induced elevation in cerebrovascular reactivity provides further support for exercise as a preventative tool in cerebrovascular and neurological disease with ageing.
PMCID: PMC3636405  PMID: 22669592
Ageing; Exercise training; Fitness; Cerebral blood flow; CO2 reactivity
11.  Biogeography and body size shuffling of aquatic salamander communities on a shifting refuge 
Freshwater habitats of coastal plains are refugia for many divergent vertebrate lineages, yet these environments are highly vulnerable to sea-level fluctuations, which suggest that resident communities have endured dynamic histories. Using the fossil record and a multi-locus nuclear phylogeny, we examine divergence times, biogeography, body size evolution and patterns of community assembly of aquatic salamanders from North American coastal plains since the Late Cretaceous. At least five salamander families occurred on the extensive Western Interior Coastal Plain (WICP), which existed from the Late Cretaceous through the Eocene. Four of these families subsequently colonized the emergent Southeastern Coastal Plain (SECP) by the Early Oligocene to Late Miocene. Three families ultimately survived and underwent extensive body size evolution in situ on the SECP. This included at least two major size reversals in recent taxa that are convergent with confamilial WICP ancestors. Dynamics of the coastal plain, major lineage extinctions and frequent extreme changes in body size have resulted in significant shuffling of the size structure of aquatic salamander communities on this shifting refuge since the Cretaceous.
PMCID: PMC3619470  PMID: 23466988
Amphibia; Caudata; coastal plain; body size evolution; community evolution; incumbency
12.  Rho GTPases 
Small GTPases  2012;3(1):1.
PMCID: PMC3398910  PMID: 22710727
13.  Small GTPases 
Small GTPases  2011;2(4):189.
PMCID: PMC3225907  PMID: 22145090
14.  Cholecystokinin-Like Peptide (DSK) in Drosophila, Not Only for Satiety Signaling 
Cholecystokinin (CCK) signaling appears well conserved over evolution. In Drosophila, the CCK-like sulfakinins (DSKs) regulate aspects of gut function, satiety and food ingestion, hyperactivity and aggression, as well as escape-related locomotion and synaptic plasticity during neuromuscular junction development. Activity in the DSK-producing neurons is regulated by octopamine. We discuss mechanisms behind CCK function in satiety, aggression, and locomotion in some detail and highlight similarities to mammalian CCK signaling.
PMCID: PMC4270250  PMID: 25566191
neuropeptide; peptide hormone; aggression; feeding; intestinal function; locomotion
15.  Systemic inflammation and lung function in young adults 
Thorax  2007;62(12):1064-1068.
Impaired lung function is associated with systemic inflammation and is a risk factor for cardiovascular disease in older adults. It is unknown when these associations emerge and to what extent they are mediated by smoking, chronic airways disease, and/or established atherosclerosis. We explored the association between the forced expiratory volume in one second (FEV1) and the systemic inflammatory marker C‐reactive protein (CRP) in young adults.
Associations between spirometric lung function and blood CRP were assessed in a population based birth cohort of approximately 1000 New Zealanders at ages 26 and 32 years. Analyses adjusted for height and sex to account for differences in predicted lung function and excluded pregnant women.
There were significant inverse associations between FEV1 and CRP at both ages. Similar results were found for the forced vital capacity. These associations were similar in men and women and were independent of smoking, asthma, and body mass index.
Reduced lung function is associated with systemic inflammation in young adults. This association is not related to smoking, asthma, or obesity. The reasons for the association are unexplained, but the findings indicate that the association between lower lung function and increased inflammation predates the development of either chronic lung disease or clinically significant atherosclerosis. The association between poor lung function and cardiovascular disease may be mediated by an inflammatory mechanism.
PMCID: PMC2094275  PMID: 17604302
inflammation; C‐reactive protein; spirometry; cohort studies
16.  The peer review process from an editor's point of view 
Small GTPases  2010;1(2):77.
PMCID: PMC3116592  PMID: 21686258
17.  Effects of Community-Based Cardiac Rehabilitation on Body Composition and Physical Function in Individuals with Stable Coronary Artery Disease: 1.6-Year Followup 
BioMed Research International  2013;2013:903604.
Objective. To examine long-term changes in physical function and body composition in coronary artery disease (CAD) patients participating in ongoing community-based cardiac rehabilitation (CR). Design. Thirty-four individuals (69.7 ± 8.2 years; 79% men) participated in this longitudinal observational study. Baseline and follow-up assessments included incremental shuttle walk, short physical performance battery, handgrip strength, chair stands, body composition, last year physical activity, and CR attendance. Results. Participants attended 38.5 ± 30.3% sessions during 1.6 ± 0.2 year followup. A significant increase in 30-second chair stands (17.0 ± 4.7 to 19.6 ± 6.4, P < 0.001), body weight (75.8 ± 11.1 to 77.2 ± 12.1 kg, P = 0.001), and body fat (27.0 ± 9.5 to 29.1 ± 9.6%, P < 0.001) and a decline in handgrip strength (36.4 ± 9.4 to 33.0 ± 10.6 kg·f, P < 0.001) and muscle mass (40.8 ± 5.6 to 39.3 ± 5.8%, P < 0.001) were observed during followup. There was no significant change in shuttle walk duration. CR attendance was not correlated to observed changes. Conclusions. Elderly CAD patients participating in a maintenance CR program improve lower-body muscle strength but experience a decline in handgrip strength and unfavourable changes in body composition, irrespective of CR attendance.
PMCID: PMC3707214  PMID: 23865071
18.  Scientific yellow journalism 
Small GTPases  2012;3(4):201.
PMCID: PMC3520881  PMID: 22995950
19.  Real-Time Analysis of Drosophila Post-Embryonic Haemocyte Behaviour 
PLoS ONE  2012;7(1):e28783.
The larval stage of the model organism Drosophila is frequently used to study host-pathogen interactions. During embryogenesis the cellular arm of the immune response, consisting of macrophage-like cells known as plasmatocytes, is extremely motile and functions to phagocytise pathogens and apoptotic bodies, as well as produce extracellular matrix. The cellular branch of the larval (post-embryonic) innate immune system consists of three cell types—plasmatocytes, crystal cells and lamellocytes—which are involved in the phagocytosis, encapsulation and melanisation of invading pathogens. Post-embryonic haemocyte motility is poorly understood thus further characterisation is required, for the purpose of standardisation.
In order to examine post-embryonic haemocyte cytoskeletal dynamics or migration, the most commonly used system is in vitro cell lines. The current study employs an ex vivo system (an adaptation of in vitro cell incubation using primary cells), in which primary larval or pre-pupal haemocytes are isolated for short term analysis, in order to discover various aspects of their behaviour during events requiring cytoskeleton dynamics.
The ex vivo method allows for real-time analysis and manipulation of primary post-embryonic haemocytes. This technique was used to characterise, and potentially standardised, larval and pre-pupal haemocyte cytoskeleton dynamics, assayed on different extracellular matrices. Using this method it was determined that, while larval haemocytes are unable to migrate, haemocytes recovered from pre-pupae are capable of migration.
PMCID: PMC3252279  PMID: 22242151
20.  The Rho-Family GTPase Rac1 Regulates Integrin Localization in Drosophila Immunosurveillance Cells 
PLoS ONE  2011;6(5):e19504.
When the parasitoid wasp Leptopilina boulardi lays an egg in a Drosophila larva, phagocytic cells called plasmatocytes and specialized cells known as lamellocytes encapsulate the egg. The Drosophila β-integrin Myospheroid (Mys) is necessary for lamellocytes to adhere to the cellular capsule surrounding L. boulardi eggs. Integrins are heterodimeric adhesion receptors consisting of α and β subunits, and similar to other plasma membrane receptors undergo ligand-dependent endocytosis. In mammalian cells it is known that integrin binding to the extracellular matrix induces the activation of Rac GTPases, and we have previously shown that Rac1 and Rac2 are necessary for a proper encapsulation response in Drosophila larvae. We wanted to test the possibility that Myospheroid and Rac GTPases interact during the Drosophila anti-parasitoid immune response.
In the current study we demonstrate that Rac1 is required for the proper localization of Myospheroid to the cell periphery of haemocytes after parasitization. Interestingly, the mislocalization of Myospheroid in Rac1 mutants is rescued by hyperthermia, involving the heat shock protein Hsp83. From these results we conclude that Rac1 and Hsp83 are required for the proper localization of Mys after parasitization.
We show for the first time that the small GTPase Rac1 is required for Mysopheroid localization. Interestingly, the necessity of Rac1 in Mys localization was negated by hyperthermia. This presents a problem, in Drosophila we quite often raise larvae at 29°C when using the GAL4/UAS misexpression system. If hyperthermia rescues receptor endosomal recycling defects, raising larvae in hyperthermic conditions may mask potentially interesting phenotypes.
PMCID: PMC3095607  PMID: 21603603
22.  The Drosophila cell adhesion molecule Neuroglian regulates Lissencephaly-1 localisation in circulating immunosurveillance cells 
BMC Immunology  2009;10:17.
When the parasitoid wasp Leptopilina boulardi lays its eggs in Drosophila larvae phagocytic cells called plasmatocytes and specialized cells known as lamellocytes encapsulate the egg. This requires these circulating immunosurveillance cells (haemocytes) to change from a non-adhesive to an adhesive state enabling them to bind to the invader. Interestingly, attachment of leukocytes, platelets, and insect haemocytes requires the same adhesion complexes as epithelial and neuronal cells.
Here evidence is presented showing that the Drosophila L1-type cell adhesion molecule Neuroglian (Nrg) is required for haemocytes to encapsulate L. boulardi wasp eggs. The amino acid sequence FIGQY containing a conserved phosphorylated tyrosine is found in the intracellular domain of all L1-type cell adhesion molecules. This conserved tyrosine is phosphorylated at the cell periphery of plasmatocytes and lamellocytes prior to parasitisation, but dephosphorylated after immune activation. Intriguingly, another pool of Nrg located near the nucleus of plasmatocytes remains phosphorylated after parasitisation. In mammalian neuronal cells phosphorylated neurofascin, another L1-type cell adhesion molecule interacts with a nucleokinesis complex containing the microtubule binding protein lissencephaly-1 (Lis1) [1]. Interestingly in plasmatocytes from Nrg mutants the nucleokinesis regulating protein Lissencephaly-1 (Lis1) fails to localise properly around the nucleus and is instead found diffuse throughout the cytoplasm and at unidentified perinuclear structures. After attaching to the wasp egg control plasmatocytes extend filopodia laterally from their cell periphery; as well as extending lateral filopodia plasmatocytes from Nrg mutants also extend many filopodia from their apical surface.
The Drosophila cellular adhesion molecule Neuroglian is expressed in haemocytes and its activity is required for the encapsulation of L. boularli eggs. At the cell periphery of haemocytes Neuroglian may be involved in cell-cell interactions, while at the cell centre Neuroglian regulates the localisation of the nucleokinesis complex protein lissencephaly-1.
PMCID: PMC2667480  PMID: 19320973
23.  Sarcoidosis presenting with Polyarthritis 
Annals of the Rheumatic Diseases  1961;20(2):138-143.
PMCID: PMC1007197  PMID: 13785473

Results 1-23 (23)