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ABSTRACT: Exosomes are 30-100 nm membrane vesicles of endocytic origin produced by numerous cells. They can mediate diverse biological functions, including antigen presentation. Exosomes have recently been shown to contain functional RNA, which can be delivered to other cells. Exosomes may thus mediate biological functions either by surface-to-surface interactions with cells, or by the delivery of functional RNA to cells. Our aim was therefore to determine the presence of RNA in exosomes from human saliva, plasma and breast milk and whether these exosomes can be taken up by macrophages.
Exosomes were purified from human saliva, plasma and breast milk using ultracentrifugation and filtration steps. Exosomes were detected by electron microscopy and examined by flow cytometry. Flow cytometry was performed by capturing the exosomes on anti-MHC class II coated beads, and further stain with anti-CD9, anti-CD63 or anti-CD81. Breast milk exosomes were further analysed for the presence of Hsc70, CD81 and calnexin by Western blot. Total RNA was detected with a Bioanalyzer and mRNA was identified by the synthesis of cDNA using an oligo (dT) primer and analysed with a Bioanalyzer. The uptake of PKH67-labelled saliva and breast milk exosomes by macrophages was examined by measuring fluorescence using flow cytometry and fluorescence microscopy.
RNA was detected in exosomes from all three body fluids. A portion of the detected RNA in plasma exosomes was characterised as mRNA. Our result extends the characterisation of exosomes in healthy humans and confirms the presence of RNA in human saliva and plasma exosomes and reports for the first time the presence of RNA in breast milk exosomes. Our results also show that the saliva and breast milk exosomes can be taken up by human macrophages.
Exosomes in saliva, plasma and breast milk all contain RNA, confirming previous findings that exosomes from several sources contain RNA. Furthermore, exosomes are readily taken up by macrophages, supporting the notion that exosomal RNA can be shuttled between cells.
Journal of Translational Medicine 01/2011; 9:9. · 3.41 Impact Factor
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ABSTRACT: Exosomes are small extracellular nanovesicles of endocytic origin that mediate different signals between cells, by surface interactions and by shuttling functional RNA from one cell to another. Exosomes are released by many cells including mast cells, dendritic cells, macrophages, epithelial cells and tumour cells. Exosomes differ compared to their donor cells, not only in size, but also in their RNA, protein and lipid composition.
In this study, we show that exosomes, released by mouse mast cells exposed to oxidative stress, differ in their mRNA content. Also, we show that these exosomes can influence the response of other cells to oxidative stress by providing recipient cells with a resistance against oxidative stress, observed as an attenuated loss of cell viability. Furthermore, Affymetrix microarray analysis revealed that the exosomal mRNA content not only differs between exosomes and donor cells, but also between exosomes derived from cells grown under different conditions; oxidative stress and normal conditions. Finally, we also show that exposure to UV-light affects the biological functions associated with exosomes released under oxidative stress.
These results argue that the exosomal shuttle of RNA is involved in cell-to-cell communication, by influencing the response of recipient cells to an external stress stimulus.
PLoS ONE 01/2010; 5(12):e15353. · 4.09 Impact Factor
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ABSTRACT: Exosomes are small vesicles of endosomal origin that can be released by many different cells to the microenvironment. Exosomes have been shown to participate in the immune system, by mediating antigen presentation. We have recently shown the presence of both mRNA and microRNA in exosomes, specifically in exosomes derived from mast cells. This RNA can be transferred between one mast cell to another, most likely through fusion of the exosome to the recipient cell membrane. The delivered RNA is functional, as the mRNA can lead to translation of new proteins in a recipient cell. The RNA shuttled between cells via exosomes is called esRNA. We propose that several types of exosomes may exist, and that an additional function of exosomes is to communicate to neighbouring cells through delivery of RNA-signals.
Cell adhesion & migration 08/2007; 1(3):156-8. · 1.82 Impact Factor
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ABSTRACT: Exosomes are vesicles of endocytic origin released by many cells. These vesicles can mediate communication between cells, facilitating processes such as antigen presentation. Here, we show that exosomes from a mouse and a human mast cell line (MC/9 and HMC-1, respectively), as well as primary bone marrow-derived mouse mast cells, contain RNA. Microarray assessments revealed the presence of mRNA from approximately 1300 genes, many of which are not present in the cytoplasm of the donor cell. In vitro translation proved that the exosome mRNAs were functional. Quality control RNA analysis of total RNA derived from exosomes also revealed presence of small RNAs, including microRNAs. The RNA from mast cell exosomes is transferable to other mouse and human mast cells. After transfer of mouse exosomal RNA to human mast cells, new mouse proteins were found in the recipient cells, indicating that transferred exosomal mRNA can be translated after entering another cell. In summary, we show that exosomes contain both mRNA and microRNA, which can be delivered to another cell, and can be functional in this new location. We propose that this RNA is called "exosomal shuttle RNA" (esRNA).
Nature Cell Biology 07/2007; 9(6):654-9. · 19.49 Impact Factor
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ABSTRACT: It is known that interleukin (IL)-23, an IL-12-family cytokine, can be released by certain antigen-presenting cells in response to bacterial pathogens. Recent in vitro studies indicate that this cytokine stimulates a unique subset of CD4 cells, the T helper cell (Th)17 subset, to produce and release the proinflammatory cytokine IL-17. However, it has not been known whether this is an action of IL-23 per se that has bearing for the early innate response in lungs in vivo and whether there is an IL-23-responsive population of IL-17-producing CD4 cells in the bronchoalveolar space. We now present evidence that IL-23 can be involved in the early innate response to both gram-negative and gram-positive bacterial products in the lungs: Recombinant IL-23 protein per se accumulates inflammatory cells in the bronchoalveolar space in part via endogenous production of IL-17, and this IL-17 production occurs locally in IL-23-responsive CD4 cells. This IL-17 response to IL-23 occurs without any pronounced impact on Th1/Th2 polarization. Moreover, recombinant IL-23 protein increases the local MMP-9 activity, which is generated by neutrophils mainly. CD4 cells in the lungs may thus respond to IL-23 from antigen-presenting cells exposed to gram-negative and gram-positive pathogens and thereby reinforce the early innate response. These findings support that IL-23 and IL-17 form a functionally relevant "immunological axis" in the lungs in vivo.
American Journal of Respiratory Cell and Molecular Biology 05/2007; 36(4):442-51. · 5.13 Impact Factor
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ABSTRACT: Yeast cells adapt to hyperosmotic shock by accumulating glycerol and altering expression of hundreds of genes. This transcriptional response of Saccharomyces cerevisiae to osmotic shock encompasses genes whose products are implicated in protection from oxidative damage. We addressed the question of whether osmotic shock caused oxidative stress. Osmotic shock did not result in the generation of detectable levels of reactive oxygen species (ROS). To preclude any generation of ROS, osmotic shock treatments were performed in anaerobic cultures. Global gene expression response profiles were compared by employing a novel two-dimensional cluster analysis. The transcriptional profiles following osmotic shock under anaerobic and aerobic conditions were qualitatively very similar. In particular, it appeared that expression of the oxidative stress genes was stimulated upon osmotic shock even if there was no apparent need for their function. Interestingly, cells adapted to osmotic shock much more rapidly under anaerobiosis, and the signaling as well as the transcriptional response was clearly attenuated under these conditions. This more rapid adaptation is due to an enhanced glycerol production capacity in anaerobic cells, which is caused by the need for glycerol production in redox balancing. Artificially enhanced glycerol production led to an attenuated response even under aerobic conditions. These observations demonstrate the crucial role of glycerol accumulation and turgor recovery in determining the period of osmotic shock-induced signaling and the profile of cellular adaptation to osmotic shock.
Eukaryotic Cell 01/2005; 3(6):1381-90. · 3.60 Impact Factor
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ABSTRACT: A strain of Saccharomyces cerevisiae lacking the GPD2 gene, encoding one of the glycerol-3-phosphate dehydrogenases, grows slowly under anaerobic conditions, due to reductive stress caused by the accumulation of cytoplasmic NADH. We used 2D-PAGE to study the effect on global protein expression of reductive stress in the anaerobically grown gpd2Delta strain. The most striking response was a strongly elevated expression of Tdh1p, the minor isoform of glyceraldehyde-3-phosphate dehydrogenase. This increased expression could be reversed by the addition of acetoin, a NADH-specific redox sink, which furthermore largely restored anaerobic growth of the gpd2Delta strain. Additional deletion of the TDH1 gene (but not of TDH2 or TDH3) improved anaerobic growth of the gpd2Delta strain. We therefore propose that TDH1 has properties not displayed by the other TDH isogenes and that its expression is regulated by reductive stress caused by an excess of cytoplasmic NADH.
Current Genetics 03/2004; 45(2):90-5. · 2.56 Impact Factor
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ABSTRACT: The yeast Saccharomyces cerevisiae produces large amounts of glycerol as an osmoregulator during hyperosmotic stress and as a redox sink at low oxygen availability. NAD+-dependent glycerol-3-phosphate dehydrogenase in S. cerevisiae is present in two isoforms, coded for by two different genes, GPD1 and GPD2. Mutants for either one or both of these genes were investigated under carefully controlled static and dynamic conditions in continuous cultures at low oxygen transfer rates. Our results show that S. cerevisiae controls the production of glycerol in response to hypoxic conditions by regulating the expression of several genes. At high demand for NADH reoxidation, a strong induction was seen not only of the GPD2 gene, but also of GPP1, encoding one of the molecular forms of glycerol-3-phosphatase. Induction of the GPP1 gene appears to play a decisive role at elevated growth rates. At low demand for NADH reoxidation via glycerol formation, the GPD1, GPD2, GPP1, and GPP2 genes were all expressed at basal levels. The dynamics of the gene induction and the glycerol formation at low demand for NADH reoxidation point to an important role of the Gpd1p; deletion of the GPD1 gene strongly altered the expression patterns of the GPD2 and GPP1 genes under such conditions. Furthermore, our results indicate that GCY1 and DAK1, tentatively encoding glycerol dehydrogenase and dihydroxyacetone kinase, respectively, may be involved in the redox regulation of S. cerevisiae. Copyright © 2000 John Wiley & Sons, Ltd.
Yeast 10/2000; 16(16):1483 - 1495. · 1.89 Impact Factor
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ABSTRACT: A cultivation set-up for multiple cultures has been designed that can be used for anaerobic screening for quantitative changes in growth rate or other analyses, e.g. protein composition of different strains. The developed gas distribution system provides a reproducible level of anaerobicity in 30 cultivation flasks and resembles the open system of a high-performance bioreactor in that it ensures cultivation at atmospheric pressure and avoids supersaturation of carbon dioxide. The system is cheap and user-friendly and allows rapid screenings of many strains simultaneously.
Journal of Microbiological Methods.
