Interaction Of Membrane Vesicles Research Articles

Tumor-Derived Membrane Vesicles from the IL-2 Overexpression Melanoma Cells Affect on the Expression of Surface Markers of Human Peripheral Blood Mononuclear Cells In Vitro

Nowadays, immunotherapy, in particular immunotherapeutic vaccines, is a promising approach in the treatment of cancer which has already demonstrated its effectiveness. Extracellular vesicles (EVs), which are capable of delivering biologically active agents to the cells, can be a promising candidate for such vaccines. M14 human melanoma cells were transduced with lentivirus encoding interleukin (IL)–2. Membrane vesicles from M14 cells expressing IL-2 were isolated using cytochalasin B. The interaction of membrane vesicles with human peripheral blood mononuclear cells has been analyzed. Activation of T cells was shown, as well as a decrease in the number of NK cells, after cultivation with tumor-derived vesicles. However, no cytotoxic activity of T cells after cultivation with tumor-derived vesicles was observed, which can be explained by their immunosuppressive properties. On the other hand, such vesicles can be a promising source of tumor-specific antigens for dendritic vaccines. Therefore, further studies are required in view of the possible use of tumor-derived vesicles as a target antigen for dendritic cells.

Interaction of membrane vesicles with the Pseudomonas functional amyloid protein FapC facilitates amyloid formation

Functional amyloids (FA) are proteins which are evolutionarily optimized to form highly stable fibrillar structures that strengthen the bacterial biofilm matrix. FA such as CsgA (E. coli) and FapC (Pseudomonas) are secreted to the bacterial surface where they integrate into growing fibril structures projecting from the outer membrane. FA are exposed to membrane surfaces in this process, but it remains unclear how membranes can interact with FA and potentially affect the self-assembly. Here we report the effect of different vesicles (DOPG, DMPG, DOPS, DOPC and DMPC) on the kinetics and structural endpoints of FapC fibrillation using various biophysical techniques. Particularly anionic lipids such as DMPG trigger FapC fibrillation, and the protein's second repeat sequence (R2) appears to be important for this interaction. Vesicles formed from phospholipids extracted from three different Pseudomonas strains (Δfap, ΔFapC and pfap) induce FapC fibrillation by accelerating nucleation. The general aggregation inhibitor epigallocatechin gallate (EGCG) inhibits FapC fibrillation by blocking interactions between FapC and vesicles and redirecting FapC monomers to oligomer structures. Our work indicates that biological membranes can contribute significantly to the fibrillation of functional amyloid.

Interaction of Membrane Vesicles with the Pseudomonas Functional Amyloid Protein FapC Facilitates Amyloid Formation

Interaction of Membrane Vesicles with the Pseudomonas Functional Amyloid Protein FapC Facilitates Amyloid Formation

Functional Analysis of Chromatin Assembled in Synthetic Nuclei

Numerous regulatory mechanisms contribute to the control of eukaryotic transcription. These controls are manifested through higher-order protein–DNA structure within the nucleus.In vitroassays have proven extremely useful in deciphering the potential regulatory roles of chromatin and nuclear structure in transcription. Embryonic egg extracts ofXenopuswith their vast maternal stores and rapid cell-cycle oscillations can be exploited to recapitulate multiple layers of nuclear regulation. Incubation of cloned DNA templates inXenopusegg extracts promotes a self-ordered assembly of physiologically spaced nucleosomes and synthetic nuclei structure formation. Interaction of membrane vesicles with chromatin leads to formation of a bilayer nuclear envelope encapsulating the DNA. These synthetic nuclei are functional organelles capable of active protein transport and a single round of semiconservative DNA synthesis. This system can be used to directly test the mechanisms by whichtrans-acting factors promote transcription on nucleosomal DNA, either during chromatin assembly or postassembly or in conjunction with remodeling machinery and/or DNA replication. The functional consequences oftrans-acting factor interaction within synthetic nuclei are determined by a coupledin vitrotranscription analysis. Immobilizing biotin end-labeled DNA templates on paramagnetic streptavidin beads greatly improves the flexibility of the system. The ease of chromatin-assembled template recovery allows the introduction of wash steps, buffer changes, and specific reaction optimization. These methods for reconstituting gene regulatory mechanismsin vitroare an attempt to strike a balance between biochemical accessibility and physiological relevance.