Interaction between endothelial differentiation-related factor-1 and calmodulin in vitro and in vivo.
Calmodulin (CaM) is the principal Ca(2+) receptor protein inside the cell. When activated by Ca(2+), CaM binds and activates target proteins, thus altering the metabolism and physiology of the cell. Under basal conditions, calcium-free CaM binds to other proteins termed CaM-binding proteins. Recently, we described endothelial differentiation-related factor (EDF)-1 as a protein involved in the repression of endothelial cell differentiation (Dragoni, I., Mariotti, M., Consalez, G. G., Soria, M., and Maier, J. A. M. (1998) J. Biol. Chem. 273, 31119-31124). Here we report that (i) EDF-1 binds CaM in vitro and in vivo; (ii) EDF-1 is phosphorylated in vitro and in vivo by protein kinase C; and (iii) EDF-1-CaM interaction is modulated by the concentrations of Ca(2+) and by the phosphorylation of EDF-1 by protein kinase C both in vitro and in vivo. In addition, 12-O-tetradecanoylphorbol-13-acetate treatment of human umbilical vein endothelial cell stimulates the nuclear translocation of EDF-1. On the basis of the high homology of EDF-1 with multiprotein bridging factor-1, a transcriptional coactivator that binds TATA-binding protein (TBP), we also demonstrate that EDF-1 interacts with TBP in vitro and in human endothelial cells. We hypothesize that EDF-1 serves two main functions in endothelial cells as follows: (i) to bind CaM in the cytosol at physiologic concentrations of Ca(2+) and (ii) to act in the nucleus as a transcriptional coactivator through its binding to TBP.
Mariotti
M
M
Department of Biomedical Sciences and Technologies, University of Milan, Italy.
De Benedictis
L
L
Avon
E
E
Maier
J A
JA
D002147:Calmodulin / Q000378:metabolism*; D002148:Calmodulin-Binding Proteins / Q000378:metabolism*; D002454:Cell Differentiation; D004268:DNA-Binding Proteins / Q000378:metabolism; D004730:Endothelium, Vascular / Q000166:cytology*; D006801:Humans; D010766:Phosphorylation; D011485:Protein Binding; D011493:Protein Kinase C / Q000378:metabolism; D035181:TATA-Box Binding Protein; D013755:Tetradecanoylphorbol Acetate / Q000494:pharmacology; D014157:Transcription Factors / Q000378:metabolism
D002147:Calmodulin; D002148:Calmodulin-Binding Proteins; D004268:DNA-Binding Proteins; C115911:EDF1 protein, human; D035181:TATA-Box Binding Protein; D014157:Transcription Factors; D011493:Protein Kinase C; D013755:Tetradecanoylphorbol Acetate