title: Phosphatidylethanolamine is externalized at the surface of microparticles.
abstract: Microparticles (MPs) are membrane-bound vesicles shed normally or as a result of various (pathological) stimuli. MPs contain a wealth of bio-active macromolecules. Aminophospholipid phosphatidylserine (PS) is present on the surface of many MPs. As PS and phosphatidylethanolamine (PE) are related, yet distinct aminophospholipids, the purpose of this study was to systematically and directly assess PE exposure on MPs. We examined MPs from various human cellular sources (human breast cancer, endothelial, red and white blood cells) by flow cytometry using a PE-specific probe, duramycin, and two PS-specific probes, annexin V and lactadherin. PS and PE exposure percentage was comparable on vascular and blood cell-derived MPs (80-90% of MP-gated events). However, the percentage of malignant breast cancer MPs exposing PE (~90%) was significantly higher than PS (~50%). Thus, while PS and PE exposure can result from a general loss of membrane asymmetry, there may also be distinct mechanisms of PE and PS exposure on MPs that vary by cellular source.
authors.affiliation: Department of Biophysics, Medical College of Wisconsin, Milwaukee, WI, 53226 USA; Blood Research Institute, Blood Center of Wisconsin, Milwaukee, WI, 53226 USA. mlarson@mcw.edu
authors.forename: Michael C
authors.initials: MC
authors.lastname: Larson
authors.forename: Jeffrey E
authors.initials: JE
authors.lastname: Woodliff
authors.forename: Cheryl A
authors.initials: CA
authors.lastname: Hillery
authors.forename: Tyce J
authors.initials: TJ
authors.lastname: Kearl
authors.forename: Ming
authors.initials: M
authors.lastname: Zhao
mesh_terms: D001430:Bacteriocins / Q000737:chemistry / Q000378:metabolism / Q000494:pharmacology; D001710:Biotin / Q000737:chemistry; D001777:Blood Coagulation / Q000187:drug effects; D001943:Breast Neoplasms / Q000378:metabolism / Q000473:pathology; D045744:Cell Line, Tumor; D002462:Cell Membrane / Q000737:chemistry / Q000378:metabolism; D055252:Cell-Derived Microparticles / Q000737:chemistry / Q000378:metabolism*; D002478:Cells, Cultured; D004305:Dose-Response Relationship, Drug; D042783:Endothelial Cells / Q000378:metabolism*; D004912:Erythrocytes / Q000378:metabolism*; D005434:Flow Cytometry; D006801:Humans; D018613:Microscopy, Confocal; D010455:Peptides / Q000737:chemistry / Q000378:metabolism / Q000494:pharmacology; D010714:Phosphatidylethanolamines / Q000737:chemistry / Q000378:metabolism*
chemical_list: D001430:Bacteriocins; D010455:Peptides; D010714:Phosphatidylethanolamines; C040522:duramycin; C483858:phosphatidylethanolamine; D001710:Biotin