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Endosome

About: Endosome is a(n) research topic. Over the lifetime, 12817 publication(s) have been published within this topic receiving 891254 citation(s). The topic is also known as: GO:0005768 & endosomes.

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Open accessJournal ArticleDOI: 10.1002/0471143030.CB0322S30
Abstract: Exosomes are small membrane vesicles found in cell culture supernatants and in different biological fluids. Exosomes form in a particular population of endosomes, called multivesicular bodies (MVBs), by inward budding into the lumen of the compartment. Upon fusion of MVBs with the plasma membrane, these internal vesicles are secreted. Exosomes possess a defined set of membrane and cytosolic proteins. The physiological function of exosomes is still a matter of debate, but increasing results in various experimental systems suggest their involvement in multiple biological processes. Because both cell-culture supernatants and biological fluids contain different types of lipid membranes, it is critical to perform high-quality exosome purification. This unit describes different approaches for exosome purification from various sources, and discusses methods to evaluate the purity and homogeneity of the purified exosome preparations.

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  • Table 3.22.2 Characteristic Protein Markers of Exosomes, as Assessed by Immunoblot
    Table 3.22.2 Characteristic Protein Markers of Exosomes, as Assessed by Immunoblot
  • Table 3.22.2 Characteristic Protein Markers of Exosomes, as Assessed by Immunoblot
    Table 3.22.2 Characteristic Protein Markers of Exosomes, as Assessed by Immunoblot
  • Figure 3.22.1 Flow chart for the exosome purification procedure based on differential ultracentrifugation. The speed and length of each centrifugation are indicated to the right of the arrows. After each of the first three centrifugations, pellets (cells, dead cells, cell debris) are discarded, and the supernatant is kept for the next step. In contrast, after the two 100,000× g centrifugations, pellets (exosomes + contaminant proteins, exosomes) are kept, and supernatants are discarded.
    Figure 3.22.1 Flow chart for the exosome purification procedure based on differential ultracentrifugation. The speed and length of each centrifugation are indicated to the right of the arrows. After each of the first three centrifugations, pellets (cells, dead cells, cell debris) are discarded, and the supernatant is kept for the next step. In contrast, after the two 100,000× g centrifugations, pellets (exosomes + contaminant proteins, exosomes) are kept, and supernatants are discarded.
  • Figure 3.22.1 Flow chart for the exosome purification procedure based on differential ultracentrifugation. The speed and length of each centrifugation are indicated to the right of the arrows. After each of the first three centrifugations, pellets (cells, dead cells, cell debris) are discarded, and the supernatant is kept for the next step. In contrast, after the two 100,000× g centrifugations, pellets (exosomes + contaminant proteins, exosomes) are kept, and supernatants are discarded.
    Figure 3.22.1 Flow chart for the exosome purification procedure based on differential ultracentrifugation. The speed and length of each centrifugation are indicated to the right of the arrows. After each of the first three centrifugations, pellets (cells, dead cells, cell debris) are discarded, and the supernatant is kept for the next step. In contrast, after the two 100,000× g centrifugations, pellets (exosomes + contaminant proteins, exosomes) are kept, and supernatants are discarded.
Topics: Exosome (69%), Exosomal secretion (52%), Circulating microvesicle (52%) ...read more

3,640 Citations


Open accessJournal ArticleDOI: 10.1042/BJ20031253
Abstract: Non-phagocytic eukaryotic cells can internalize particles <1 microm in size, encompassing pathogens, liposomes for drug delivery or lipoplexes applied in gene delivery. In the present study, we have investigated the effect of particle size on the pathway of entry and subsequent intracellular fate in non-phagocytic B16 cells, using a range of fluorescent latex beads of defined sizes (50-1000 nm). Our data reveal that particles as large as 500 nm were internalized by cells via an energy-dependent process. With an increase in size (50-500 nm), cholesterol depletion increased the efficiency of inhibition of uptake. The processing of the smaller particles was significantly perturbed upon microtubule disruption, while displaying a negligible effect on that of the 500 nm beads. Inhibitor and co-localization studies revealed that the mechanism by which the beads were internalized, and their subsequent intracellular routing, was strongly dependent on particle size. Internalization of microspheres with a diameter <200 nm involved clathrin-coated pits. With increasing size, a shift to a mechanism that relied on caveolae-mediated internalization became apparent, which became the predominant pathway of entry for particles of 500 nm in size. At these conditions, delivery to the lysosomes was no longer apparent. The data indicate that the size itself of (ligand-devoid) particles can determine the pathway of entry. The clathrin-mediated pathway of endocytosis shows an upper size limit for internalization of approx. 200 nm, and kinetic parameters may determine the almost exclusive internalization of such particles along this pathway rather than via caveolae.

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Topics: Internalization (60%), Particle size (53%), Endosome (53%) ...read more

2,415 Citations


Journal ArticleDOI: 10.1126/SCIENCE.1153124
29 Feb 2008-Science
Abstract: Intraluminal vesicles of multivesicular endosomes are either sorted for cargo degradation into lysosomes or secreted as exosomes into the extracellular milieu. The mechanisms underlying the sorting of membrane into the different populations of intraluminal vesicles are unknown. Here, we find that cargo is segregated into distinct subdomains on the endosomal membrane and that the transfer of exosome-associated domains into the lumen of the endosome did not depend on the function of the ESCRT (endosomal sorting complex required for transport) machinery, but required the sphingolipid ceramide. Purified exosomes were enriched in ceramide, and the release of exosomes was reduced after the inhibition of neutral sphingomyelinases. These results establish a pathway in intraendosomal membrane transport and exosome formation.

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Topics: Exosome (63%), Endosome (59%), ESCRT (58%) ...read more

2,315 Citations


Juan S. Bonifacino1, Linton M. TraubInstitutions (1)
Abstract: Sorting of transmembrane proteins to endosomes and lysosomes is mediated by signals present within the cytosolic domains of the proteins. Most signals consist of short, linear sequences of amino acid residues. Some signals are referred to as tyrosine-based sorting signals and conform to the NPXY or YXXO consensus motifs. Other signals known as dileucine-based signals fit [DE]XXXL[LI] or DXXLL consensus motifs. All of these signals are recognized by components of protein coats peripherally associated with the cytosolic face of membranes. YXXO and [DE]XXXL[LI] signals are recognized with characteristic fine specificity by the adaptor protein (AP) complexes AP-1, AP-2, AP-3, and AP-4, whereas DXXLL signals are recognized by another family of adaptors known as GGAs. Several proteins, including clathrin, AP-2, and Dab2, have been proposed to function as recognition proteins for NPXY signals. YXXO and DXXLL signals bind in an extended conformation to the mu2 subunit of AP-2 and the VHS domain of the GGAs, respectively. Phosphorylation events regulate signal recognition. In addition to peptide motifs, ubiquitination of cytosolic lysine residues also serves as a signal for sorting at various stages of the endosomal-lysosomal system. Conjugated ubiquitin is recognized by UIM, UBA, or UBC domains present within many components of the internalization and lysosomal targeting machinery. This complex array of signals and recognition proteins ensures the dynamic but accurate distribution of transmembrane proteins to different compartments of the endosomal-lysosomal system.

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Topics: Clathrin adaptor complex (54%), Signal transducing adaptor protein (53%), Endosome (53%) ...read more

1,941 Citations


Open accessJournal ArticleDOI: 10.1083/JCB.116.5.1071
Abstract: THE definition of cellular organelles has evolved over the last hundred years largely driven by morphologic observations, but more recently has been supplemented and complemented by functional and biochemical studies (Palade, 1975) . Thus, organelles are now identified both by their morphology and by the set ofcomponents that comprise them . Determining how organelle identity is established and maintained and how newly synthesized protein and membrane are sorted to different organelles are the central issues of organellogenesis . Essential to the many cellular functions that take place within the central vacuolar system (which consists ofthe ER, Golgi apparatus, secretory vesicles, endosomes, and lysosomes) is membrane traffic which mediates the exchange of components between different organelles . There are two critical characteristics of membrane traffic . First, only certain sets oforganelles exchange membrane and the patterns of this exchange define what are called membrane pathways . Second, multiple pathways intersect at specific points within the central vacuolar system . For specific components to "choose" the correct pathway at such points of crossing, mechanisms exist to impose choices on specific molecules . This process is called sorting . The characteristicsofeachorganelle within the central vacuolar system are likely to be intimately tied to the properties ofmembrane traffic . An imbalance in the magnitude ofmembrane input into and egress from an organelle would have profound effects on the size ofthat compartment . In addition, failures in sorting or aberrations in targeting pathways would be expected to profoundly affect the identity of individual organelles . Recently, the relationship between the control of membrane traffic and the maintenance of organelle structure has been investigated with the use ofa remarkable drug, brefeldin A (BFA).' In this review we will summarize recent findings with BFA and propose some speculative models concerning the mechanism and regulation ofmembrane traffic within the central vacuolar system .

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Topics: Vesicular-tubular cluster (56%), Endosome (51%), Golgi apparatus (51%) ...read more

1,805 Citations


Performance
Metrics
No. of papers in the topic in previous years
YearPapers
20227
2021475
2020532
2019478
2018484
2017480

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Topic's top 5 most impactful authors

Harald Stenmark

111 papers, 16.2K citations

Jean Gruenberg

87 papers, 13.3K citations

Robert G. Parton

82 papers, 16.8K citations

Philip D. Stahl

63 papers, 7.5K citations

Graça Raposo

57 papers, 17.8K citations

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