Journal Article•
Ongoing activition of sphingosine 1-phosphate receptors mediates maturation of exosomal multivesicular endosomes
TL;DR: It is shown that inhibitory G protein (Gi)-coupled sphingosine 1-phosphate (S1P) receptors regulate exosomal MVE maturation, and that the continuous activation of Gi- coupled S1P receptors on MVEs is essential for cargo sorting into ILVs destined for exosome release.
Abstract: During late endosome maturation, cargo molecules are sorted into intralumenal vesicles (ILVs) of multivesicular endosomes (MVEs), and are either delivered to lysosomes for degradation or fused with the plasma membranes for exosome release. The mechanism underlying formation of exosomal ILVs and cargo sorting into ILVs destined for exosome release is still unclear. Here we show that inhibitory G protein (Gi)-coupled sphingosine 1-phosphate (S1P) receptors regulate exosomal MVE maturation. Gi-coupled S1P receptors on MVEs are constitutively activated through a constant supply of S1P via autocrine activation within organelles. We also found that the continuous activation of Gi-coupled S1P receptors on MVEs is essential for cargo sorting into ILVs destined for exosome release. Our results reveal a mechanism underlying ESCRT-independent maturation of exosomal MVEs.
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TL;DR: Extracellular vesicles are now considered as an additional mechanism for intercellular communication, allowing cells to exchange proteins, lipids and genetic material.
Abstract: Extracellular vesicles are a heterogeneous group of cell-derived membranous structures comprising exosomes and microvesicles, which originate from the endosomal system or which are shed from the plasma membrane, respectively They are present in biological fluids and are involved in multiple physiological and pathological processes Extracellular vesicles are now considered as an additional mechanism for intercellular communication, allowing cells to exchange proteins, lipids and genetic material Knowledge of the cellular processes that govern extracellular vesicle biology is essential to shed light on the physiological and pathological functions of these vesicles as well as on clinical applications involving their use and/or analysis However, in this expanding field, much remains unknown regarding the origin, biogenesis, secretion, targeting and fate of these vesicles
4,241 citations
TL;DR: What is presently known about how exosomes are formed and released by cells is summarized and other cellular processes related to exosome biogenesis and release, such as autophagy and lysosomal exocytosis are presented.
Abstract: Exosomes are nanosized membrane vesicles released by fusion of an organelle of the endocytic pathway, the multivesicular body, with the plasma membrane. This process was discovered more than 30 years ago, and during these years, exosomes have gone from being considered as cellular waste disposal to mediate a novel mechanism of cell-to-cell communication. The exponential interest in exosomes experienced during recent years is due to their important roles in health and disease and to their potential clinical application in therapy and diagnosis. However, important aspects of the biology of exosomes remain unknown. To explore the use of exosomes in the clinic, it is essential that the basic molecular mechanisms behind the transport and function of these vesicles are better understood. We have here summarized what is presently known about how exosomes are formed and released by cells. Moreover, other cellular processes related to exosome biogenesis and release, such as autophagy and lysosomal exocytosis are presented. Finally, methodological aspects related to exosome release studies are discussed.
1,502 citations
TL;DR: This review focuses on recent findings and knowledge gaps in the area of EV biogenesis, release, and uptake and highlights examples whereby EV cargoes control basic cellular functions, including motility and polarization, immune responses, and development, and contribute to diseases such as cancer and neurodegeneration.
952 citations
Cites background from "Ongoing activition of sphingosine 1..."
...Certain cargoes have been shown to preferentially depend on ceramide synthesis [31,32] for their presence in ILVs of MVB....
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TL;DR: How the cellular context affects the composition of exosomes, and thus the outcome of the communication between the exosome-producer and recipient cells, is discussed, with particular focus on the Communication between tumor cells and with cells of the tumor microenvironment.
581 citations
Cites background from "Ongoing activition of sphingosine 1..."
...Another sphingomyelin metabolite, sphyngosine-1-phosphate (S1P), was recently shown to play a key role in MVB biogenesis [31]....
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TL;DR: The aim of this review is to reveal the emerging roles of exosomes in normal and pathological conditions and describe the controversial biological role ofExosomes, as it is now understood, in carcinogenesis.
Abstract: Intercellular communication via cell-released vesicles is a very important process for both normal and tumor cells. Cell communication may involve exosomes, small vesicles of endocytic origin that are released by all types of cells and are found in abundance in body fluids, including blood, saliva, urine, and breast milk. Exosomes have been shown to carry lipids, proteins, mRNAs, non-coding RNAs, and even DNA out of cells. They are more than simply molecular garbage bins, however, in that the molecules they carry can be taken up by other cells. Thus, exosomes transfer biological information to neighboring cells and through this cell-to-cell communication are involved not only in physiological functions such as cell-to-cell communication, but also in the pathogenesis of some diseases, including tumors and neurodegenerative conditions. Our increasing understanding of why cells release exosomes and their role in intercellular communication has revealed the very complex and sophisticated contribution of exosomes to health and disease. The aim of this review is to reveal the emerging roles of exosomes in normal and pathological conditions and describe the controversial biological role of exosomes, as it is now understood, in carcinogenesis. We also summarize what is known about exosome biogenesis, composition, functions, and pathways and discuss the potential clinical applications of exosomes, especially as biomarkers and novel therapeutic agents.
364 citations
Cites background from "Ongoing activition of sphingosine 1..."
...Silencing of S1P1 receptors impairs the formation of CD63-, CD81-, or flotillin-positive exosomes [58]....
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References
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TL;DR: The physical properties that define exosomes as a specific population of secreted vesicles are described, their biological effects, particularly on the immune system, are summarized, and the potential roles that secretedvesicles could have as intercellular messengers are discussed.
Abstract: Exosomes are small membrane vesicles of endocytic origin that are secreted by most cells in culture. Interest in exosomes has intensified after their recent description in antigen-presenting cells and the observation that they can stimulate immune responses in vivo. In the past few years, several groups have reported the secretion of exosomes by various cell types, and have discussed their potential biological functions. Here, we describe the physical properties that define exosomes as a specific population of secreted vesicles, we summarize their biological effects, particularly on the immune system, and we discuss the potential roles that secreted vesicles could have as intercellular messengers.
4,380 citations
TL;DR: Extracellular vesicles are now considered as an additional mechanism for intercellular communication, allowing cells to exchange proteins, lipids and genetic material.
Abstract: Extracellular vesicles are a heterogeneous group of cell-derived membranous structures comprising exosomes and microvesicles, which originate from the endosomal system or which are shed from the plasma membrane, respectively They are present in biological fluids and are involved in multiple physiological and pathological processes Extracellular vesicles are now considered as an additional mechanism for intercellular communication, allowing cells to exchange proteins, lipids and genetic material Knowledge of the cellular processes that govern extracellular vesicle biology is essential to shed light on the physiological and pathological functions of these vesicles as well as on clinical applications involving their use and/or analysis However, in this expanding field, much remains unknown regarding the origin, biogenesis, secretion, targeting and fate of these vesicles
4,241 citations
TL;DR: The data show that exosome production, transfer and education of bone marrow cells supports tumor growth and metastasis, has prognostic value and offers promise for new therapeutic directions in the metastatic process.
Abstract: Tumor-derived exosomes are emerging mediators of tumorigenesis. We explored the function of melanoma-derived exosomes in the formation of primary tumors and metastases in mice and human subjects. Exosomes from highly metastatic melanomas increased the metastatic behavior of primary tumors by permanently 'educating' bone marrow progenitors through the receptor tyrosine kinase MET. Melanoma-derived exosomes also induced vascular leakiness at pre-metastatic sites and reprogrammed bone marrow progenitors toward a pro-vasculogenic phenotype that was positive for c-Kit, the receptor tyrosine kinase Tie2 and Met. Reducing Met expression in exosomes diminished the pro-metastatic behavior of bone marrow cells. Notably, MET expression was elevated in circulating CD45(-)C-KIT(low/+)TIE2(+) bone marrow progenitors from individuals with metastatic melanoma. RAB1A, RAB5B, RAB7 and RAB27A, regulators of membrane trafficking and exosome formation, were highly expressed in melanoma cells. Rab27A RNA interference decreased exosome production, preventing bone marrow education and reducing, tumor growth and metastasis. In addition, we identified an exosome-specific melanoma signature with prognostic and therapeutic potential comprised of TYRP2, VLA-4, HSP70, an HSP90 isoform and the MET oncoprotein. Our data show that exosome production, transfer and education of bone marrow cells supports tumor growth and metastasis, has prognostic value and offers promise for new therapeutic directions in the metastatic process.
3,076 citations
TL;DR: It is found that cargo is segregated into distinct subdomains on the endosomal membrane and that the transfer of exosome-associated domains into the lumen of theendosome did not depend on the function of the ESCRT (endosomal sorting complex required for transport) machinery, but required the sphingolipid ceramide.
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.
2,818 citations
French Institute of Health and Medical Research1, Instituto de Medicina Molecular2, Curie Institute3, Centre national de la recherche scientifique4, National Institutes of Health5, Harvard University6, Broad Institute7, Tohoku University8, Universidade Nova de Lisboa9, Instituto Gulbenkian de Ciência10
TL;DR: The results therefore strengthen the link between MVEs and exosomes, and introduce ways of manipulating exosome secretion in vivo.
Abstract: Exosomes are secreted membrane vesicles that share structural and biochemical characteristics with intraluminal vesicles of multivesicular endosomes (MVEs). Exosomes could be involved in intercellular communication and in the pathogenesis of infectious and degenerative diseases. The molecular mechanisms of exosome biogenesis and secretion are, however, poorly understood. Using an RNA interference (RNAi) screen, we identified five Rab GTPases that promote exosome secretion in HeLa cells. Among these, Rab27a and Rab27b were found to function in MVE docking at the plasma membrane. The size of MVEs was strongly increased by Rab27a silencing, whereas MVEs were redistributed towards the perinuclear region upon Rab27b silencing. Thus, the two Rab27 isoforms have different roles in the exosomal pathway. In addition, silencing two known Rab27 effectors, Slp4 (also known as SYTL4, synaptotagmin-like 4) and Slac2b (also known as EXPH5, exophilin 5), inhibited exosome secretion and phenocopied silencing of Rab27a and Rab27b, respectively. Our results therefore strengthen the link between MVEs and exosomes, and introduce ways of manipulating exosome secretion in vivo.
2,006 citations