title: Fibrinogen gamma-chain mRNA is not detected in human megakaryocytes.
abstract: Human megakaryocytes and platelets contain counterparts of several plasma proteins. The origin of most of these alpha-granule proteins is unclear. Fibrinogen represents one of those molecules, being essential in hemostasis, thrombosis, and platelet aggregation. To study whether fibrinogen is endocytosed by megakaryocytes and packaged into alpha-granules or newly synthesized by these cells, we established a highly sensitive nested primer polymerase chain reaction for the detection of human fibrinogen gamma-chain mRNA. In enriched megakaryocyte fractions, as well as fluorescence-activated cell sorter-purified megakaryocytes from bone marrow samples of healthy volunteers, no fibrinogen gamma-chain mRNA could be detected, despite the presence of the corresponding fibrinogen gamma-chain DNA. We conclude that fibrinogen gamma-chain mRNA, as detectable by our amplification system, is missing in megakaryocytes. This finding suggests that fibrinogen might be acquired from plasma by endocytosis and sequestered in alpha-granules before reentering the circulation after platelet activation.
authors.affiliation: Department Medicine I, Hematology and Oncology, Albert-Ludwigs University Medical Center, Freiburg, Germany.
authors.forename: W
authors.initials: W
authors.lastname: Lange
authors.forename: A
authors.initials: A
authors.lastname: Luig
authors.forename: G
authors.initials: G
authors.lastname: Dölken
authors.forename: R
authors.initials: R
authors.lastname: Mertelsmann
authors.forename: L
authors.initials: L
authors.lastname: Kanz
mesh_terms: D001483:Base Sequence; D003594:Cytoplasmic Granules / Q000737:chemistry; D004247:DNA / Q000032:analysis / Q000235:genetics; D004587:Electrophoresis, Agar Gel; D005340:Fibrinogen / Q000235:genetics* / Q000378:metabolism; D005434:Flow Cytometry / Q000379:methods; D006801:Humans; D008533:Megakaryocytes / Q000737:chemistry*; D008969:Molecular Sequence Data; D010949:Plasma / Q000737:chemistry / Q000378:metabolism; D016133:Polymerase Chain Reaction; D012333:RNA, Messenger / Q000032:analysis* / Q000235:genetics
chemical_list: D012333:RNA, Messenger; C027539:fibrinopeptides gamma; D005340:Fibrinogen; D004247:DNA