How synthetic membrane systems contribute to the understanding of lipid-driven endocytosis

Schubert, Thomas; Römer, Winfried

doi:10.1016/j.bbamcr.2015.07.014

Cited by 32 publications

(36 citation statements)

References 147 publications

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“…The data open obvious questions about the GGT-operated signal transduction pathways upstream NFkB activation including the mechanisms allowing membrane permeation of the exogenous protein and the interaction with its intracellular targets. Although our results cannot answer this specific point, one might conjecture of a specific but insofar not identified GGT-receptor or lipid-driven endocytosis [32]. Perhaps, some role may play a chemokine-like CX3C motif contained in the GGT molecule [33] or exogenous GGT might mimick cytokine-like activities of GGT-related proteins produced by genes different from the GGT1 [34].…”

Section: Discussionmentioning

confidence: 95%

Non enzymatic upregulation of tissue factor expression by gamma-glutamyl transferase in human peripheral blood mononuclear cells

et al. 2016

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BackgroundBesides maintaining intracellular glutathione stores, gamma-glutamyltransferase(GGT) generates reactive oxygen species and activates NFkB, a redox-sensitive transcription factor key in the induction of Tissue Factor (TF) gene expression, the principal initiator of the clotting cascade. Thus, GGT might be involved in TF-mediated coagulation processes, an assumption untested insofar.MethodsExperiments were run with either equine, enzymatically active GGT or human recombinant (hr) GGT, a wheat germ-derived protein enzymatically inert because of missing post-translational glycosylation. TF Procoagulant Activity (PCA, one-stage clotting assay), TF antigen(ELISA) and TFmRNA(real-time PCR) were assessed in unpooled human peripheral blood mononuclear cell(PBMC) suspensions obtained from healthy donors through discontinuous Ficoll/Hystopaque density gradient.ResultsEquine GGT increased PCA, an effect insensitive to GGT inhibition by acivicin suggesting mechanisms independent of its enzymatic activity, a possibility confirmed by the maintained stimulation in response to hrGGT, an enzymatically inactive molecule. Endotoxin(LPS) contamination of GGT preparations was excluded by heat inactivation studies and direct determination(LAL method) of LPS concentrations <0.1 ng/mL practically devoid of procoagulant effect. Inhibition by anti-GGT antibodies corroborated that conclusion. Upregulation by hrGGT of TF antigen and mRNA and its downregulation by BAY-11-7082, a NFkB inhibitor, and N-acetyl-L-cysteine, an antioxidant, was consistent with a NFkB-driven, redox-sensitive transcriptional site of action.ConclusionsGGT upregulates TF expression independent of its enzymatic activity, a cytokine-like behaviour mediated by NFκB activation, a mechanism contributing to promote acute thrombotic events, a possibility in need, however, of further evaluation.

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Section: Discussionmentioning

confidence: 95%

Non enzymatic upregulation of tissue factor expression by gamma-glutamyl transferase in human peripheral blood mononuclear cells

et al. 2016

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“…In this section we have highlighted some applications of protocells to gain a more detailed understanding of endocytosis processes. For more details, especially about lipid-driven endocytosis, we refer readers to previously published reviews [105,111,112]. Except for the combined MA/OT techniques, which have been used in above-mentioned examples [92,93,109], other micromanipulation techniques can be applied to study, for example, phagocytosis in artificial membrane systems.…”

Section: Application Of Glycan-decorated Protocells In Endocytosismentioning

confidence: 99%

Glycan-decorated protocells: novel features for rebuilding cellular processes

Omidvar

Römer

2019

Interface Focus.

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In synthetic biology approaches, lipid vesicles are widely used as protocell models. While many compounds have been encapsulated in vesicles (e.g. DNA, cytoskeleton and enzymes), the incorporation of glycocalyx components in the lipid bilayer has attracted much less attention so far. In recent years, glycoconjugates have been integrated in the membrane of giant unilamellar vesicles (GUVs). These minimal membrane systems have largely contributed to shed light on the molecular mechanisms of cellular processes. In this review, we first introduce several preparation and biophysical characterization methods of GUVs. Then, we highlight specific applications of protocells investigating glycolipid-mediated endocytosis of toxins, viruses and bacteria. In addition, we delineate how prototissues have been assembled from glycan-decorated protocells by using lectin-mediated cross-linking of opposed glycoreceptors (e.g. glycolipids and glycopeptides). In future applications, glycan-decorated protocells might be useful for investigating cell–cell interactions (e.g. adhesion and communication). We also speculate about the implication of lectin–glycoreceptor interactions in membrane fusion processes.

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“…In addition, other functional tags can be selectively attached to the peptide chain. The presented approach is of course not limited to GUVs, but can be employed for any biomimetic lipid membrane, such as supported lipid bilayers . Furthermore, it should also enable new glyco‐targeted delivery strategies for vesicle‐enclosed drugs in selected disease models.…”

Section: Methodsmentioning

confidence: 99%

“…Native cell membranes have heterogeneous compositions,h owever,s oi ti sc hallenging to study mechanistic details of interactions between distinct proteins or lipids within them directly.O ne way to overcome this challenge is to use minimal membrane systems: giant unilamellar vesicles (GUVs), for example. [1] Synthetic vesicles have been successfully used to study biophysical phenomenas uch as phase separation in lipid membranes that mimic the cell membrane lipid composition. [2] Furthermore, GUVs have also been employed to reconstitute complex biological processes such as the induction of endocytic processes by bacterial proteins.…”

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confidence: 99%

“…The presented approachi so f course not limited to GUVs, but can be employed for any biomimeticl ipid membrane, such as supportedl ipid bilayers. [1] Furthermore, it should also enablen ew glyco-targeted delivery strategies for vesicle-enclosed drugs in selected disease models. Even on surfaces not intended for direct mimicry of cell surfaces the lipidated glycopeptides should be of advantage.…”

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confidence: 99%

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Synthesis of Cholesterol‐Substituted Glycopeptides for Tailor‐Made Glycocalyxification of Artificial Membrane Systems

et al. 2016

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Synthetic minimal membrane systems are extremely useful for better understanding of complex cellular structures and cell surface processes. We have developed a facile method for synthesis of cholesterylated peptides, each bearing a carbohydrate moiety and a fluorescent tag. The position of the cholesterol moiety on the peptide can be controlled by using a new Fmoc-protected cholesterol-triazole-lysine group, which we constructed by means of solid-phase peptide synthesis. We succeeded in integrating the glyco modules into giant unilamellar vesicles by electroformation or infusion in buffer solution. The glyco-decorated liposomes were recognized by a lectin and had unique topological membrane features. In conclusion, this work is a proof of principle for the functionalization of artificial membranes with a primitive synthetic glycocalyx useful for studying carbohydrate-protein interactions on a simplified cell-like membrane surface.

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How synthetic membrane systems contribute to the understanding of lipid-driven endocytosis

Cited by 32 publications

References 147 publications

Non enzymatic upregulation of tissue factor expression by gamma-glutamyl transferase in human peripheral blood mononuclear cells

Non enzymatic upregulation of tissue factor expression by gamma-glutamyl transferase in human peripheral blood mononuclear cells

Glycan-decorated protocells: novel features for rebuilding cellular processes

Synthesis of Cholesterol‐Substituted Glycopeptides for Tailor‐Made Glycocalyxification of Artificial Membrane Systems

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