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Endocytosis of plasma‐derived factor V by megakaryocytes occurs via a clathrin‐dependent, specific membrane binding event
Author(s) -
BOUCHARD B. A.,
WILLIAMS J. L.,
MEISLER N. T.,
LONG M. W.,
TRACY P. B.
Publication year - 2005
Publication title -
journal of thrombosis and haemostasis
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.947
H-Index - 178
eISSN - 1538-7836
pISSN - 1538-7933
DOI - 10.1111/j.1538-7836.2005.01190.x
Subject(s) - endocytosis , megakaryocyte , microbiology and biotechnology , tissue factor , platelet , biology , chemistry , cell , immunology , medicine , progenitor cell , coagulation , biochemistry , stem cell
Summary. Megakaryocytes were analyzed for their ability to endocytose factor V to define the cellular mechanisms regulating this process. In contrast to fibrinogen, factor V was endocytosed by megakaryocytes derived from CD34 + cells or megakaryocyte‐like cell lines, but not by platelets. CD41 + ex vivo ‐derived megakaryocytes endocytosed factor V, as did subpopulations of the megakaryocyte‐like cells MEG‐01, and CMK. Similar observations were made for fibrinogen. Phorbol diester‐induced megakaryocytic differentiation of the cell lines resulted in a substantial increase in endocytosis of both proteins as compared to untreated cells that did not merely reflect their disparate plasma concentrations. Factor IX, which does not associate with platelets or megakaryocytes, was not endocytosed by any of the cells examined. Endocytosis of factor V by megakaryocytes proceeds through a specific and independent mechanism as CHRF‐288 cells endocytosed fibrinogen but not factor V, and the presence of other plasma proteins had no effect on the endocytosis of factor V by MEG‐01 cells. Furthermore, as the endocytosis of factor V was also demonstrated to occur through a clathrin‐dependent mechanism, these combined data demonstrate that endocytosis of factor V by megakaryocytes occurs via a specific, independent, and most probably receptor‐mediated, event.