This MedLibrary.org supplementary page on Microvesicles is provided directly from the open source Wikipedia as a service to our readers. Please see the note below on authorship of this content, as well as the Wikipedia usage guidelines. To search for other content from our encyclopedia supplement, please use the form below:
Related Sponsors
Microvesicles are fragments of plasma membrane ranging from 100nm to 700nm shed from almost all cell types during activation. They originate directly from the plasma membrane of the cell and reflect the antigenic content of the cells which they originate from. It has recently been found that microvesicles can deliver mRNA between cells (1), leading to speculation on their possible role in intercellular exchange of genetic material.
Mechanism of shedding of MV
Under physiologic condition, the plasma membrane of cells has an asymmetric distribution of their phospholipids. Aminophospholipids, phosphatidylserine and phosphatidilethanolammine, are specifically sequestered in the inner leaflet of the membrane. The transbilayer lipid distribution is under the control of 3 phospholipidic pumps: an inward-directed pump, a flippase, an outward-directed pump, or floppase and a lipid scramblase, responsible for a non specific redistribution of lipids across the membrane. After cell stimulation, including apoptosis, a subsequent cytosolic Ca2+ increase, promotes the lost of the phospholipids asymmetry of the plasma membrane, subsequent phosphatidylserine exposure and there is a transient phospholipidic imbalance between the external leaflet at the expense of the inner leaflet leading blebbing of the plasmamembrane and microvesicles release (2).
References:
(1) Ratajczak J, Miekus K, Kucia M, Zhang J, Reca R, Dvorak P, Ratajczak MZ. (2006)Embryonic stem cell-derived microvesicles reprogram hematopoietic progenitors: evidence for horizontal transfer of mRNA and protein delivery. Leukemia 20:847-56
(2) Hugel B, MartÃnez MC, Kunzelmann C, Freyssinet JM.(2005) Membrane microparticles: two sides of the coin. Physiology (Bethesda) 20:22-7
External links
Wikipedia content modification information:
- This page was last modified on 20 March 2008, at 22:16.
Wikipedia Authorship and Review
Wikipedia content provided here is not reviewed directly by MedLibrary.org. Wikipedia content is authored by an open community of volunteers and is not produced by or in any way affiliated with MedLibrary.org.
Wikipedia Usage Guidelines
This article is licensed under the GNU Free Documentation License. It uses material from the Wikipedia article on "Microvesicles".
The URL for this specific entry is:
All Wikipedia text is available under the terms of the GNU Free Documentation License. (See Copyrights for details). Wikipedia® is a registered trademark of the Wikimedia Foundation, Inc.