Fibroblast growth factor-stimulated phosphorylation of a lipocortin I-like protein is S-phase cell cycle specific in human vascular endothelial cells.
We examined whether the phosphorylation of a 34 kDa lipocortin I-like protein may be associated with internalization process of fibroblast growth factor (FGF) in human umbilical vein endothelial (HUVE) cells. We show that: 1) exposure of synchronized HUVE cells to basic FGF for an appreciable time lag (> or = 30 min) at 37 degrees C and subsequent phosphorylation at 37 degrees C are required to obtain an increased 32P-labelling of a 34 kDa substrate; 2) this FGF-stimulated phosphorylation occurs in S phase but not G1 phase of the growth cycle; 3) the 34 kDa substrate appears to be phosphorylated on tyrosine residues; 4) a major fraction of the 34 kDa 32P-labelled substrate is immunoprecipitated with an antibody that has been raised against human lipocortin/annexin of type I. It is suggested that internalized FGF-receptor/kinase complexes might be primarily responsible for the phosphorylation of the 34 kDa lipocortin I-related protein in S phase HUVE cells.
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Unité de Recherches Gérontologiques, INSERM U. 118, Paris, France.
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D017305:Annexin A1 / Q000378:metabolism*; D002478:Cells, Cultured; D004730:Endothelium, Vascular / Q000166:cytology / Q000378:metabolism*; D005346:Fibroblast Growth Factors / Q000502:physiology*; D006801:Humans; D015151:Immunoblotting; D007700:Kinetics; D010766:Phosphorylation; D016196:S Phase
D017305:Annexin A1; D005346:Fibroblast Growth Factors