The dual role of endothelial differentiation-related factor-1 in the cytosol and nucleus: modulation by protein kinase A.
Endothelial differentiation-related factor (EDF)-1 is involved in the repression of endothelial cell differentiation and is the first studied calmodulin (CaM)-binding protein in endothelial cells. Here we report that (i) EDF-1 is in vitro and in vivo phosphorylated by protein kinase A (PKA); (ii) EDF-1/CaM interaction is modulated by the phosphorylation of EDF-1 by PKA; (iii) forskolin stimulates nuclear accumulation of EDF-1, and (iv) PKA phosphorylation enhances EDF-1 interaction with the TATA-binding protein. CaM modulates the activity of several enzymes, among which is nitric oxide synthase (NOS). EDF-1, but not phosphorylated EDF-1, inhibits the activity of NOS. Accordingly, we detected an increase in NOS activity in cells that express low amounts of EDF-1. Our results indicate that EDF-1 serves two main functions in endothelial cells: (i) it regulates CaM availability in the cytosol, and (ii) it acts in the nucleus as a transcriptional coactivator.
Ballabio
E
E
DIBIT-H San Raffaele, Milan, Italy.
Mariotti
M
M
De Benedictis
L
L
Maier
J A M
JA
D002148:Calmodulin-Binding Proteins / Q000378:metabolism*; D002467:Cell Nucleus / Q000378:metabolism*; D017868:Cyclic AMP-Dependent Protein Kinases / Q000378:metabolism*; D003600:Cytosol / Q000378:metabolism*; D042783:Endothelial Cells / Q000378:metabolism; D004730:Endothelium, Vascular / Q000378:metabolism; D006801:Humans; D009569:Nitric Oxide / Q000096:biosynthesis; D019001:Nitric Oxide Synthase / Q000378:metabolism; D010766:Phosphorylation; D035181:TATA-Box Binding Protein / Q000378:metabolism
D002148:Calmodulin-Binding Proteins; C115911:EDF1 protein, human; D035181:TATA-Box Binding Protein; D009569:Nitric Oxide; D019001:Nitric Oxide Synthase; D017868:Cyclic AMP-Dependent Protein Kinases