6 results on '"van der Laan AM"'
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2. Correction: Variant Exported Blood-Stage Proteins Encoded by Plasmodium Multigene Families Are Expressed in Liver Stages Where They Are Exported into the Parasitophorous Vacuole.
- Author
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Fougère A, Jackson AP, Paraskevi Bechtsi D, Braks JA, Annoura T, Fonager J, Spaccapelo R, Ramesar J, Chevalley-Maurel S, Klop O, van der Laan AM, Tanke HJ, Kocken CH, Pasini EM, Khan SM, Böhme U, van Ooij C, Otto TD, Janse CJ, and Franke-Fayard B more...
- Abstract
[This corrects the article DOI: 10.1371/journal.ppat.1005917.].
- Published
- 2016
- Full Text
- View/download PDF
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3. Variant Exported Blood-Stage Proteins Encoded by Plasmodium Multigene Families Are Expressed in Liver Stages Where They Are Exported into the Parasitophorous Vacuole.
- Author
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Fougère A, Jackson AP, Bechtsi DP, Braks JA, Annoura T, Fonager J, Spaccapelo R, Ramesar J, Chevalley-Maurel S, Klop O, van der Laan AM, Tanke HJ, Kocken CH, Pasini EM, Khan SM, Böhme U, van Ooij C, Otto TD, Janse CJ, and Franke-Fayard B more...
- Subjects
- Animals, Disease Models, Animal, Erythrocytes parasitology, Fluorescent Antibody Technique, Humans, Liver, Malaria, Falciparum virology, Mice, Multigene Family, Organisms, Genetically Modified, Phylogeny, Plasmodium falciparum, Protein Transport, Vacuoles virology, Hepatocytes virology, Malaria, Falciparum metabolism, Protozoan Proteins metabolism
- Abstract
Many variant proteins encoded by Plasmodium-specific multigene families are exported into red blood cells (RBC). P. falciparum-specific variant proteins encoded by the var, stevor and rifin multigene families are exported onto the surface of infected red blood cells (iRBC) and mediate interactions between iRBC and host cells resulting in tissue sequestration and rosetting. However, the precise function of most other Plasmodium multigene families encoding exported proteins is unknown. To understand the role of RBC-exported proteins of rodent malaria parasites (RMP) we analysed the expression and cellular location by fluorescent-tagging of members of the pir, fam-a and fam-b multigene families. Furthermore, we performed phylogenetic analyses of the fam-a and fam-b multigene families, which indicate that both families have a history of functional differentiation unique to RMP. We demonstrate for all three families that expression of family members in iRBC is not mutually exclusive. Most tagged proteins were transported into the iRBC cytoplasm but not onto the iRBC plasma membrane, indicating that they are unlikely to play a direct role in iRBC-host cell interactions. Unexpectedly, most family members are also expressed during the liver stage, where they are transported into the parasitophorous vacuole. This suggests that these protein families promote parasite development in both the liver and blood, either by supporting parasite development within hepatocytes and erythrocytes and/or by manipulating the host immune response. Indeed, in the case of Fam-A, which have a steroidogenic acute regulatory-related lipid transfer (START) domain, we found that several family members can transfer phosphatidylcholine in vitro. These observations indicate that these proteins may transport (host) phosphatidylcholine for membrane synthesis. This is the first demonstration of a biological function of any exported variant protein family of rodent malaria parasites., Competing Interests: The authors have declared that no competing interests exist. more...
- Published
- 2016
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4. Circulating MicroRNAs Characterizing Patients with Insufficient Coronary Collateral Artery Function.
- Author
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Hakimzadeh N, Nossent AY, van der Laan AM, Schirmer SH, de Ronde MW, Pinto-Sietsma SJ, van Royen N, Quax PH, Hoefer IE, and Piek JJ
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- Aged, Female, Humans, Leukocytes classification, Male, Middle Aged, Collateral Circulation genetics, Coronary Vessels physiopathology, MicroRNAs blood
- Abstract
Background: Coronary collateral arteries function as natural bypasses in the event of coronary obstruction. The degree of collateral network development significantly impacts the outcome of patients after an acute myocardial infarction (AMI). MicroRNAs (miRNAs, miRs) have arisen as biomarkers to identify heterogeneous patients, as well as new therapeutic targets in cardiovascular disease. We sought to identify miRNAs that are differentially expressed in chronic total occlusion (CTO) patients with well or poorly developed collateral arteries., Methods and Results: Forty-one CTO patients undergoing coronary angiography and invasive assessment of their coronary collateralization were dichotomized based on their collateral flow index (CFI). After miRNA profiling was conducted on aortic plasma, four miRNAs were selected for validation by real-time quantitative reverse transcription polymerase chain reaction in patients with low (CFI<0.39) and high (CFI>0.39) collateral artery capacity. We confirmed significantly elevated levels of miR423-5p (p<0.05), miR10b (p<0.05), miR30d (p<0.05) and miR126 (p<0.001) in patients with insufficient collateral network development. We further demonstrated that each of these miRNAs could serve as circulating biomarkers to discriminate patients with low collateral capacity (p<0.01 for each miRNA). We also determined significantly greater expression of miR30d (p<0.05) and miR126 (p<0.001) in CTO patients relative to healthy controls., Conclusion: The present study identifies differentially expressed miRNAs in patients with high versus low coronary collateral capacity. We have shown that these miRNAs can function as circulating biomarkers to discriminate between patients with insufficient or sufficient collateralization. This is the first study to identify miRNAs linked to coronary collateral vessel function in humans. more...
- Published
- 2015
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5. Galectin-2 induces a proinflammatory, anti-arteriogenic phenotype in monocytes and macrophages.
- Author
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Yıldırım C, Vogel DY, Hollander MR, Baggen JM, Fontijn RD, Nieuwenhuis S, Haverkamp A, de Vries MR, Quax PH, Garcia-Vallejo JJ, van der Laan AM, Dijkstra CD, van der Pouw Kraan TC, van Royen N, and Horrevoets AJ more...
- Subjects
- Animals, CD40 Antigens biosynthesis, Cell Differentiation, Cells, Cultured, Collateral Circulation drug effects, Dendritic Cells metabolism, Galectin 2 deficiency, Galectin 2 genetics, Galectin 2 pharmacology, Gene Expression Regulation, Humans, Lectins, C-Type biosynthesis, Lipopolysaccharide Receptors immunology, Lipopolysaccharide Receptors physiology, Macrophages classification, Macrophages drug effects, Mannose Receptor, Mannose-Binding Lectins biosynthesis, Mice, Mice, Inbred C57BL, Mice, Knockout, Monocytes drug effects, Phenotype, Protein Binding drug effects, RAW 264.7 Cells, Receptors, Cell Surface biosynthesis, Recombinant Fusion Proteins metabolism, Recombinant Fusion Proteins pharmacology, Signal Transduction, T-Lymphocytes metabolism, Toll-Like Receptor 4 metabolism, Collateral Circulation physiology, Galectin 2 physiology, Inflammation physiopathology, Macrophages physiology, Monocytes physiology
- Abstract
Galectin-2 is a monocyte-expressed carbohydrate-binding lectin, for which increased expression is genetically determined and associated with decreased collateral arteriogenesis in obstructive coronary artery disease patients. The inhibiting effect of galectin-2 on arteriogenesis was confirmed in vivo, but the mechanism is largely unknown. In this study we aimed to explore the effects of galectin-2 on monocyte/macrophage phenotype in vitro and vivo, and to identify the receptor by which galectin-2 exerts these effects. We now show that the binding of galectin-2 to different circulating human monocyte subsets is dependent on monocyte surface expression levels of CD14. The high affinity binding is blocked by an anti-CD14 antibody but not by carbohydrates, indicating a specific protein-protein interaction. Galectin-2 binding to human monocytes modulated their transcriptome by inducing proinflammatory cytokines and inhibiting pro-arteriogenic factors, while attenuating monocyte migration. Using specific knock-out mice, we show that galectin-2 acts through the CD14/toll-like receptor (TLR)-4 pathway. Furthermore, galectin-2 skews human macrophages to a M1-like proinflammatory phenotype, characterized by a reduced motility and expression of an anti-arteriogenic cytokine/growth factor repertoire. This is accompanied by a switch in surface protein expression to CD40-high and CD206-low (M1). In a murine model we show that galectin-2 administration, known to attenuate arteriogenesis, leads to increased numbers of CD40-positive (M1) and reduced numbers of CD206-positive (M2) macrophages surrounding actively remodeling collateral arteries. In conclusion galectin-2 is the first endogenous CD14/TLR4 ligand that induces a proinflammatory, non-arteriogenic phenotype in monocytes/macrophages. Interference with CD14-Galectin-2 interaction may provide a new intervention strategy to stimulate growth of collateral arteries in genetically compromised cardiovascular patients. more...
- Published
- 2015
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6. In vivo monitoring of mRNA movement in Drosophila body wall muscle cells reveals the presence of myofiber domains.
- Author
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van Gemert AM, van der Laan AM, Pilgram GS, Fradkin LG, Noordermeer JN, Tanke HJ, and Jost CR
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- Animals, Animals, Genetically Modified, Base Sequence, DNA Primers, Green Fluorescent Proteins genetics, Immunohistochemistry, Microscopy, Confocal, Microscopy, Electron, RNA, Messenger genetics, Drosophila embryology, Muscles metabolism, Myofibrils metabolism, RNA, Messenger metabolism
- Abstract
Background: In skeletal muscle each muscle cell, commonly called myofiber, is actually a large syncytium containing numerous nuclei. Experiments in fixed myofibers show that mRNAs remain localized around the nuclei in which they are produced., Methodology/principal Findings: In this study we generated transgenic flies that allowed us to investigate the movement of mRNAs in body wall myofibers of living Drosophila embryos. We determined the dynamic properties of GFP-tagged mRNAs using in vivo confocal imaging and photobleaching techniques and found that the GFP-tagged mRNAs are not free to move throughout myofibers. The restricted movement indicated that body wall myofibers consist of three domains. The exchange of mRNAs between the domains is relatively slow, but the GFP-tagged mRNAs move rapidly within these domains. One domain is located at the centre of the cell and is surrounded by nuclei while the other two domains are located at either end of the fiber. To move between these domains mRNAs have to travel past centrally located nuclei., Conclusions/significance: These data suggest that the domains made visible in our experiments result from prolonged interactions with as yet undefined structures close to the nuclei that prevent GFP-tagged mRNAs from rapidly moving between the domains. This could be of significant importance for the treatment of myopathies using regenerative cell-based therapies. more...
- Published
- 2009
- Full Text
- View/download PDF
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