| Summary: | 碩士 === 長庚大學 === 醫學生物技術研究所 === 97 === Megakaryocytes are derived from hematopoietic stem cell in the bone marrow, and express integrin (alpha)IIb(beta)3 that can bind and uptake their ligand fibrinogen and stored in (alpha)-granule during megakaryocyte maturation. An endocytosis associated protein Disabled-2 (DAB2) is up-regulated and translocates to membrane interacting with integrin (beta)3 in the progress of megakaryocyte differentiation. Based on these studies, we are interested in investigating whether DAB2 is involved in integrin (alpha)IIb(beta)3-mediated fibrinogen endocytosis, and in integrin (alpha)IIb(beta)3 signaling pathway. First we used K562 cell line to establish the hematopoietic cell differentiation system. We found that megakaryocyte-like cells can uptake fibrinogen but this endocytosis was decreased in DAB2-knockdown cells. In addition, we used(alpha)IIb(beta)3-transfected CHO-K1 cells as a model system to confirm that fibrinogen endocytosis is an integrin (alpha)IIb(beta)3 dependent mechanism. Furthermore, we utilized the immunofluorescence staining to observe the distribution of fibrinogen, DAB2 and clathrin, and found they colocalized with each other. We also found that fibrinogen endocytosis can be blocked with hypertonic buffer, it means endocytosis of fibrinogen by megakaryocytes occurs via a clathrin-dependent process. This study demonstrates for the first time that DAB2 interacts with clathrin complex that play a role in the regulation of fibrinogen endocytosis during megakaryocytic differentiation.
|
|---|
