Neuropilin-1 forms complexes with vascular endothelial growth factor receptor-2 during megakaryocytic differentiation of UT-7/TPO cells.
We investigated whether the gene expression of vascular endothelial growth factor (VEGF) and its receptors (VEGFR and neuropilin-1 [NRP-1]) could be specifically regulated during the megakaryocytic differentiation of human thrombopoietin (TPO)-dependent UT-7/TPO cells. Undifferentiated UT-7/TPO cells expressed a functional VEGFR-2, leading to VEGF binding and VEGF(165)-induced tyrosine phosphorylation, cell proliferation, and apoptosis inhibition. The megakaryocytic differentiation of UT-7/TPO cells on treatment with phorbol myristate acetate (PMA) was accompanied by a marked up-regulation of NRP-1 mRNA and protein expression and by an increase in VEGF-binding activity, which was mainly mediated by VEGFR-2. VEGF(165) promoted the formation of complexes containing NRP-1 and VEGFR-2 in undifferentiated UT-7/TPO cells in a dose-dependent manner. Unlike human umbilical vein endothelial cells, PMA-differentiated UT-7/TPO cells exhibited complex formation between NRP-1 and VEGFR-2 even in the absence of VEGF(165). These findings suggest that NRP-1-VEGFR-2-complex formation may contribute to effective cellular functions mediated by VEGF(165) in megakaryocytic cells.
Department of Transfusion Medicine and Stem Cell Regulation, Juntendo University School of Medicine, 2-1-1 Hongo, Bunkyo-ku, Tokyo 113-8421, Japan. ohsaka@juntendo.ac.jp
Akimichi
A
Ohsaka
Satoko
S
Hirota-Komatsu
Miki
M
Shibata
Norio
N
Komatsu
D002454:Cell Differentiation; D002460:Cell Line; D006801:Humans; D008533:Megakaryocytes / Q000166:cytology* / Q000378:metabolism; D039942:Neuropilin-1 / Q000378:metabolism*; D040301:Vascular Endothelial Growth Factor Receptor-2 / Q000378:metabolism*
D039942:Neuropilin-1; D040301:Vascular Endothelial Growth Factor Receptor-2