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Bases moléculaires de la clairance des exosomes de réticulocyte.

Abstract : Exosomes are small membrane vesicles secreted in the extracellular space by various celle, most of them being haematopoeitic cells. The mechanism leading to their biogenesis begins to be understood, involving the endosomal machinery and the formation of a multivesicular body (MVB). Fusion of MVB with the plasma membrane leads to the release of intralumenal vesicles called exosomes. In the case of antigen presenting cells, several studies gave a physiological role for exosomes in the antigen presentation.
The presented work demonstrates that reticulocyte-secreted exosomes are part of a cellular program allowing membrane remodeling by specific shedding of some proteins that became obsolete or dangerous at this point of red cell differentiation. Our results strongly suggest that, once released in the bloodstream, reticulocyte-secreted exosomes are eliminated by a mechanims similar to the one involved in apoptotic corpses removal. An endosomal iPLA2, actived both by reactive oxygen species (ROS) released during mitoptosis and a caspace-3 located into the vesicles, can generate lysophosphatidylcholine (LPC) on exosome surface. LPC is then recognized by natural IgMs leading to activation of the complement pathway. In a similar way, ApoH interacts with reticulocyte-secreted exosomes via recognition of phosphatidylserine and could contribute to their clearance. Indeed binding of thse opsonins on exosomal surface could finally favour their uptake by phagocytes.
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https://tel.archives-ouvertes.fr/tel-00229752
Contributor : Annie Bosch-Savary <>
Submitted on : Thursday, January 31, 2008 - 4:31:45 PM
Last modification on : Friday, May 24, 2019 - 10:39:42 AM
Long-term archiving on: : Monday, May 3, 2010 - 4:23:31 PM

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  • HAL Id : tel-00229752, version 1

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Lionel Blanc. Bases moléculaires de la clairance des exosomes de réticulocyte.. Biologie cellulaire. Université Montpellier II - Sciences et Techniques du Languedoc, 2008. Français. ⟨tel-00229752⟩

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