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VEGFR‐1/FLT‐1 is induced by protein kinase C and its Ectodomain Cleavage is regulated by glycosylation and metalloproteases
Author(s) -
Raikwar Nandita S,
Liu Kang Z,
Thomas Christie P
Publication year - 2012
Publication title -
the faseb journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.709
H-Index - 277
eISSN - 1530-6860
pISSN - 0892-6638
DOI - 10.1096/fasebj.26.1_supplement.750.2
Subject(s) - ectodomain , microbiology and biotechnology , chemistry , tyrosine kinase , receptor tyrosine kinase , metalloproteinase , angiogenesis , adam10 , kinase insert domain receptor , kinase , signal transduction , biology , biochemistry , receptor , vascular endothelial growth factor , vascular endothelial growth factor a , matrix metalloproteinase , disintegrin , cancer research , vegf receptors
Vascular endothelial growth factor receptor‐1/fms‐related tyrosine kinase 1 (VEGF‐1/FLT‐1) is a membrane bound receptor tyrosine kinase involved in angiogenesis and vasculogenesis. In vascular endothelial cells, the protein kinase C agonist phorbol 12‐myristate 13‐acetate (PMA) stimulates Flt1 expression and promotes the cleavage of Flt1. To explore the regulation of Flt1 biogenesis and cleavage we expressed FLT‐1 with N and C terminal epitopes in HEK 293cells. We observed that Flt1 expression is strongly induced by PMA in a time dependent manner with an N‐terminal soluble fragment in conditioned media and a~60 kDa intracellular C‐terminal fragment. Heparin treatment led to increase in the ectodomain of FLT‐1 in conditioned media suggesting that the cleaved form of Flt1 although extracellular is bound to the cell surface proteoglycans as described for soluble Flt1(sFlt1). Application of pharmacological ER and Golgi stress agents inhibited glycosylation of Flt1 and completely blocked the cleavage and release of the ectodomain of FLT‐1. Co‐expression of the metalloproteases ADAM10 or ADAM17 significantly reduced full length FLT‐1 expression consistent with enhanced cleavage. Together our data suggests that post translational proteolytic cleavage of FLT‐1 releases its extracellular domain in the media and this release is modulated in part by heparin binding, glycosylation and metalloproteases. NIDDK