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GPI-linked protein

Sahishna Phaniraj, Zhe Gao, Digamber Rane, Blake R Peterson
The endoplasmic reticulum (ER) of eukaryotic cells plays critical roles in the processing of secreted and transmembrane proteins. Defects in these functions are associated with a wide range of pathologies. To image this organelle, cells are often treated with fluorescent ER-Tracker dyes. Although these compounds are selective, existing red fluorescent probes of the ER are costly glibenclamide derivatives that inhibit ER-associated sulphonylurea receptors. To provide simpler and more cost-effective red fluorescent probes of the ER, we synthesized amino analogues of the fluorophore resorufin...
December 2016: Dyes and Pigments: An International Journal
Andreas J W Hartel, Marius Glogger, Nicola G Jones, Wasim Abuillan, Christopher Batram, Anne Hermann, Susanne F Fenz, Motomu Tanaka, Markus Engstler
The protein density in biological membranes can be extraordinarily high, but the impact of molecular crowding on the diffusion of membrane proteins has not been studied systematically in a natural system. The diversity of the membrane proteome of most cells may preclude systematic studies. African trypanosomes, however, feature a uniform surface coat that is dominated by a single type of variant surface glycoprotein (VSG). Here we study the density-dependence of the diffusion of different glycosylphosphatidylinositol-anchored VSG-types on living cells and in artificial membranes...
September 19, 2016: Nature Communications
Katsuyoshi Horibata, Akiko Ukai, Shigeo Ishikawa, Ayako Sugano, Masamitsu Honma
The recently introduced Pig-a in vivo gene mutation assay measures endogeneous mutations of Pig-a (human, PIG-A), an X-linked gene that is conserved across species from rodents to humans. Flow cytometric analysis enables the enumeration of glycosylphosphatidylinositol (GPI) anchor-deficient erythrocytes, resulting from a mutation in Pig-a/PIG-A, in only a few microliters of peripheral blood. Pig-a/PIG-A mutations appear to function in a neutral manner, allowing evaluation of the accumulated genotoxic effects of repeated exposures...
September 15, 2016: Mutation Research. Genetic Toxicology and Environmental Mutagenesis
Susanne Heider, John A Dangerfield, Christoph Metzner
Glycosylphosphatidylinositol (GPI)-anchored proteins (GPI-APs) use a unique posttranslational modification to link proteins to lipid bilayer membranes. The anchoring structure consists of both a lipid and carbohydrate portion and is highly conserved in eukaryotic organisms regarding its basic characteristics, yet highly variable in its molecular details. The strong membrane targeting property has made the anchors an interesting tool for biotechnological modification of lipid membrane-covered entities from cells through extracellular vesicles to enveloped virus particles...
October 2016: Journal of Lipid Research
Roméo Karl Imboumy-Limoukou, Sidney Maghendi-Nzondo, Charlene Lady Kouna, Lotfi Bounaadja, Sophie Mbang, Jean Claude Biteghe, Carole Eboumbou, Franck Prugnolle, Isabelle Florent, Jean-Bernard Lekana-Douki
Pf113 is a P. falciparum putatively GPI-anchored protein that has been so far localized at the surface of merozoites, suggesting it could interact with RBC surface during merozoite invasion. Previous studies conducted in Papua New Guinea and in Kenya have revealed that this protein is recognized by natural antibodies in individuals living in malaria-endemic areas and is associated with protective immunity in malaria, further supporting the potential of Pf113 for the development of anti-malaria vaccines. However, in Central Africa, no study on the immunogenicity of this protein has been conducted...
November 2016: Acta Tropica
Diana Borovikova, Renata Teparić, Vladimir Mrša, Alexander Rapoport
The state of anhydrobiosis is linked with the reversible delay of metabolism as a result of strong dehydration of cells, and is widely distributed in nature. A number of factors responsible for the maintenance of organisms' viability in these conditions have been revealed. This study was directed to understanding how changes in cell wall structure may influence the resistance of yeasts to dehydration-rehydration. Mutants lacking various cell wall mannoproteins were tested to address this issue. It was revealed that mutants lacking proteins belonging to two structurally and functionally unrelated groups (proteins non-covalently attached to the cell wall, and Pir proteins) possessed significantly lower cell resistance to dehydration-rehydration than the mother wild-type strain...
August 2016: Yeast
Andreas Kronbichler, Moin A Saleem, Björn Meijers, Jae Il Shin
Focal segmental glomerulosclerosis (FSGS) is one of the primary glomerular disorders in both children and adults which can progress to end-stage renal failure. Although there are genetic and secondary causes, circulating factors have also been regarded as an important factor in the pathogenesis of FSGS, because about 40% of the patients with FSGS have recurrence after renal transplantation. Soluble urokinase-type plasminogen activator receptor (suPAR) is a soluble form of uPAR, which is a membrane-bound protein linked to GPI in various immunologically active cells, including podocytes...
2016: Journal of Immunology Research
R Weiss, A Bitton, L Nahary, M T Arango, I Benhar, M Blank, Y Shoenfeld, J Chapman
Antiphospholipid syndrome (APS) affects coagulation and the brain by autoimmune mechanisms. The major antigen in APS is beta-2-glycoprotein I (β2-GPI) is known to complex with annexin A2 (ANXA2), and antibodies to ANXA2 have been described in APS. We measured these antibodies in mice with experimental APS (eAPS) induced by immunization with β2-GPI. Sera of these mice reacted significantly with recombinant ANXA2 by enzyme-linked immunosorbent assay (ELISA) and the eAPS mice had significantly high levels of immunoglobulin G (IgG) in the brain by immunoblot assays compared to adjuvant immunized controls...
July 23, 2016: Immunologic Research
David Freestone, Delphine Denoyer, Matthew Jakab, M Leigh Ackland, Michael A Cater, Agnes Michalczyk
Ceruloplasmin (Cp) is a multicopper ferroxidase that is considered to be an important source of copper in milk for normal neonatal development. We investigated the expression, subcellular localization and secretion of Cp in PMC42-LA cell culture models representative of resting, lactating and suckled human mammary epithelia. Both secreted Cp (sCp) and plasma membrane associated glycosylphosphatidylinositol-linked Cp (GPI-Cp) were expressed in PMC42-LA cells. In all three epithelial models (resting, lactating and suckled), the expression and secretion of copper-bound, ferroxidase active, Cp (holo-Cp) was dependent on media copper concentration...
September 1, 2016: Metallomics: Integrated Biometal Science
Zachary Oaks, Thomas Winans, Tiffany Caza, David Fernandez, Yuxin Liu, Steve K Landas, Katalin Banki, Andras Perl
BACKGROUND: Anti-phospholipid antibodies (aPL) constitute a diagnostic criterion of systemic lupus erythematosus (SLE). aPL have been linked to liver disease in SLE. Since the mechanistic target of rapamycin (mTOR) is a regulator of oxidative stress, which contributes to the development of aPL, we examined the involvement of liver mitochondria in mouse lupus pathogenesis. METHODS: Mitochondria were isolated from lupus-prone MRL/lpr, C57BL/6.lpr and MRL mice, age-matched C57BL/6 negative controls, and transaldolase-deficient mice which exhibit oxidative stress in the liver...
June 22, 2016: Arthritis & Rheumatology
Elizaveta Katorcha, Saurabh Srivastava, Nina Klimova, Ilia V Baskakov
Prions or PrP(Sc) are proteinaceous infectious agents that consist of misfolded, self-replicating states of the prion protein or PrP(C) PrP(C) is posttranslationally modified with N-linked glycans and a sialylated glycosylphosphatidylinositol (GPI) anchor. Conformational conversion of PrP(C) gives rise to glycosylated and GPI-anchored PrP(Sc) The question of the sialylation status of GPIs within PrP(Sc) has been controversial. Previous studies that examined scrapie brains reported that both sialo- and asialo-GPIs were present in PrP(Sc), with the majority being asialo-GPIs...
August 12, 2016: Journal of Biological Chemistry
Joohae Park, Mark Hulsman, Mark Arentshorst, Matthijs Breeman, Ebru Alazi, Ellen L Lagendijk, Marina C Rocha, Iran Malavazi, Benjamin M Nitsche, Cees A M J J van den Hondel, Vera Meyer, Arthur F J Ram
The biosynthesis of cell surface-located galactofuranose (Galf)-containing glycostructures such as galactomannan, N-glycans and O-glycans in filamentous fungi is important to secure the integrity of the cell wall. UgmA encodes an UDP-galactopyranose mutase, which is essential for the formation of Galf. Consequently, the ΔugmA mutant lacks Galf-containing molecules. Our previous work in Aspergillus niger work suggested that loss of function of ugmA results in activation of the cell wall integrity (CWI) pathway which is characterized by increased expression of the agsA gene, encoding an α-glucan synthase...
September 2016: Cellular Microbiology
Maria Stella Ritorto, Heidrun Rhode, Arndt Vogel, Jürgen Borlak
Recent research implicated glycosylphosphatidylinositol-anchored proteins (GPI-AP) and GPI-specific phospholipase-D (GPI-PLD) in the pathogenesis of fatty liver disease and hepatocellular carcinoma (HCC). Given that c-Myc is frequently amplified in HCC we investigated their regulation in a c-Myc transgenic disease model of liver cancer and HCC patient samples. Whole genome scans defined 54 significantly regulated genes coding for GPI-anchored proteins of which 29 and 14 were repressed in expression in transgenic tumors and steatotic human hepatocyte cultures, respectively to influence lipid-mediated signal transduction, extracellular matrix and immunity pathways...
May 27, 2016: Biological Chemistry
Lihong Liu, Michael Wen, Qianqian Zhu, Jason T Kimata, Paul Zhou
Lipid rafts of the plasma membrane have been shown to be gateways for HIV-1 budding and entry. In nature, many glycosyl-phosphatidylinositol (GPI) anchored proteins are targeted to the lipid rafts. In the present study we constructed two fusion genes, in which C34 peptide or AVF peptide control was genetically linked with a GPI-attachment signal. Recombinant lentiviruses expressing the fusion genes were used to transduce and CEMss-CCR5 cells. Here, we show that with a GPI attachment signal both C34 and AVF are targeted to the lipid rafts through a GPI anchor...
September 2016: Journal of Neuroimmune Pharmacology: the Official Journal of the Society on NeuroImmune Pharmacology
Berta Puig, Hermann C Altmeppen, Sarah Ulbrich, Luise Linsenmeier, Susanne Krasemann, Karima Chakroun, Claudia Y Acevedo-Morantes, Holger Wille, Jörg Tatzelt, Markus Glatzel
Misfolding of proteins in the biosynthetic pathway in neurons may cause disturbed protein homeostasis and neurodegeneration. The prion protein (PrP(C)) is a GPI-anchored protein that resides at the plasma membrane and may be misfolded to PrP(Sc) leading to prion diseases. We show that a deletion in the C-terminal domain of PrP(C) (PrPΔ214-229) leads to partial retention in the secretory pathway causing a fatal neurodegenerative disease in mice that is partially rescued by co-expression of PrP(C). Transgenic (Tg(PrPΔ214-229)) mice show extensive neuronal loss in hippocampus and cerebellum and activation of p38-MAPK...
2016: Scientific Reports
Jeffrey S Rush, Thangaiah Subramanian, Karunai Leela Subramanian, Fredrick O Onono, Charles J Waechter, H Peter Spielmann
BACKGROUND: Dolichyl phosphate-linked mono- and oligosaccharides (DLO) are essential intermediates in protein N-glycosylation, C- and O-mannosylation and GPI anchor biosynthesis. While many membrane proteins in the endoplasmic reticulum (ER) involved in the assembly of DLOs are known, essential proteins believed to be required for the transbilayer movement (flip-flopping) and proteins potentially involved in the regulation of DLO synthesis remain to be identified. METHODS: The synthesis of a series of Dol-P derivatives composed of citronellyl-based photoprobes with benzophenone groups equipped with alkyne moieties for Huisgen "click" chemistry is now described to utilize as tools for identifying ER proteins involved in regulating the biosynthesis and transbilayer movement of lipid intermediates...
2015: Current Chemical Biology
Ryu Okumura, Takashi Kurakawa, Takashi Nakano, Hisako Kayama, Makoto Kinoshita, Daisuke Motooka, Kazuyoshi Gotoh, Taishi Kimura, Naganori Kamiyama, Takashi Kusu, Yoshiyasu Ueda, Hong Wu, Hideki Iijima, Soumik Barman, Hideki Osawa, Hiroshi Matsuno, Junichi Nishimura, Yusuke Ohba, Shota Nakamura, Tetsuya Iida, Masahiro Yamamoto, Eiji Umemoto, Koichi Sano, Kiyoshi Takeda
Colonic epithelial cells are covered by thick inner and outer mucus layers. The inner mucus layer is free of commensal microbiota, which contributes to the maintenance of gut homeostasis. In the small intestine, molecules critical for prevention of bacterial invasion into epithelia such as Paneth-cell-derived anti-microbial peptides and regenerating islet-derived 3 (RegIII) family proteins have been identified. Although there are mucus layers providing physical barriers against the large number of microbiota present in the large intestine, the mechanisms that separate bacteria and colonic epithelia are not fully elucidated...
April 7, 2016: Nature
Paul A Howles, Leigh K Gebbie, David A Collings, Arvind Varsani, Ronan C Broad, Stephen Ohms, Rosemary J Birch, Ann H Cork, Tony Arioli, Richard E Williamson
The putative RNA helicase encoded by the Arabidopsis gene At1g32490 is a homolog of the yeast splicing RNA helicases Prp2 and Prp22. We isolated a temperature-sensitive allele (rsw12) of the gene in a screen for root radial swelling mutants. Plants containing this allele grown at the restrictive temperature showed weak radial swelling, were stunted with reduced root elongation, and contained reduced levels of cellulose. The role of the protein was further explored by microarray analysis. By using both fold change cutoffs and a weighted gene coexpression network analysis (WGCNA) to investigate coexpression of genes, we found that the radial swelling phenotype was not linked to genes usually associated with primary cell wall biosynthesis...
May 2016: Plant Molecular Biology
E V Abakushina
The review presents main characteristics of human natural killer cells (NK-cells), their phenotype and methods of detection of functional activities using flow cytometry. The NK-cells play important role in inherent and adaptive immunity against infections and tumors. Initially these cells were characterized on the basis of capacity to lyse malignant and infected cells without preliminary sensibilization or immunization. The human NK-cells have phenotype CD3-CD56+CD16+ and can be separated in two subpopulations depending on level of expression CD56...
November 2015: Klinicheskaia Laboratornaia Diagnostika
Sander A A Kooijmans, Clara Gómez Aleza, Steve R Roffler, Wouter W van Solinge, Pieter Vader, Raymond M Schiffelers
BACKGROUND: Extracellular vesicles (EVs) are attractive candidate drug delivery systems due to their ability to functionally transport biological cargo to recipient cells. However, the apparent lack of target cell specificity of exogenously administered EVs limits their therapeutic applicability. In this study, we propose a novel method to equip EVs with targeting properties, in order to improve their interaction with tumour cells. METHODS: EV producing cells were transfected with vectors encoding for anti-epidermal growth factor receptor (EGFR) nanobodies, which served as targeting ligands for tumour cells, fused to glycosylphosphatidylinositol (GPI) anchor signal peptides derived from decay-accelerating factor (DAF)...
2016: Journal of Extracellular Vesicles
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