Fibrinogen gamma-chain mRNA is not detected in human megakaryocytes.
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.
Lange
W
W
Department Medicine I, Hematology and Oncology, Albert-Ludwigs University Medical Center, Freiburg, Germany.
Luig
A
A
Dölken
G
G
Mertelsmann
R
R
Kanz
L
L
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
D012333:RNA, Messenger; C027539:fibrinopeptides gamma; D005340:Fibrinogen; D004247:DNA