Posts Tagged: cell-derived microparticles

Microvesicles as Cell–Cell Messengers in Cardiovascular Diseases

Microvesicles as Cell–Cell Messengers in Cardiovascular Diseases

Xavier Loyer, Anne-Clémence Vion, Alain Tedgui, Chantal M. Boulanger

Mechanisms involving extracellular vesicles in cell-to-cell communication. Once released, exosomes, microparticles, and apoptotic bodies target recipient cells and are able to transfer information (microRNAs, proteins, etc) by membrane fusion (1), endocytosis (2), or receptor-mediated binding (3). (Illustration credit: Ben Smith). [Powerpoint File]

Circulating MicroRNAs: Novel Biomarkers and Extracellular Communicators in Cardiovascular Disease?

Circulating MicroRNAs: Novel Biomarkers and Extracellular Communicators in Cardiovascular Disease?

Esther E. Creemers, Anke J. Tijsen, Yigal M. Pinto

Cellular release mechanisms and extracellular transportation systems of miRNAs. In the nucleus, miRNAs are transcribed from DNA. A precursor hairpin miRNA (pre-miRNA) is formed after cleavage by the RNase III enzyme Drosha. After being transported into the cytoplasm, the pre-miRNA can be further cleaved into 19- to 23-nucleotide mature miRNA duplexes. One strand of the miRNA duplex can be loaded into the RNA-induced silencing complex (RISC), where it can guide the RISC to specific mRNA targets to prevent translation of the mRNA into protein (1). The other strand may be degraded or released from the cell through export mechanisms described below. In the cytoplasm, pre-miRNAs can also be incorporated into small vesicles called exosomes, which originate from the endosome and are released from cells when multivesicular bodies (MVB) fuse with the plasma membrane (2). Cytoplasmic miRNAs (pre-miRNA or mature miRNA) can also be released by microvesicles, which are released from the cell through blebbing of the plasma membrane (3). miRNAs are also found in circulation in microparticle-free form. These miRNAs can be associated with high-density lipoproteins or bound to RNA-binding proteins such as Ago2. It is not known how these miRNA-protein complexes are released from the cell. These miRNAs may be released passively, as by-products of dead cells, or actively, in an miRNA-specific manner, through interaction with specific membrane channels or proteins (4). Although pre-miRNAs have been detected in exosomes and microvesicles,20 and mature miRNAs have been found in complex with Ago28 and HDL,9 the exact proportion of mature and pre-miRNAs in the different extracellular compartments is not known. Illustration credit: Cosmocyte/Ben Smith. [Powerpoint File]