Apelin (65-77) activates p70 S6 kinase and is mitogenic for umbilical endothelial cells.
We report here that apelin (65-77) activates p70 S6 kinase (p70S6K), not only in CHO cells that have been stably transfected with the apelin receptor, but also in umbilical endothelial cells (HUVEC), which express it endogenously. Apelin (65-77) induces a time-dependent phosphorylation of p70S6K at residues T421/S424 and T389. This dual phosphorylation is associated with two transduction cascades, involving a PI3K pathway and an ERK pathway, respectively. The PI3K pathway, which can be blocked by wortmannin, leads to phosphorylation of Akt at residues T308 or S473, which then promotes the phosphorylation of p70S6K at T421/S424 and T389. The ERK pathway is blocked by PD 098059, a MEK inhibitor, and results in the phosphorylation of p70S6K at T421/S424. Phosphorylation both of Akt and p70S6K is abrogated by pretreatment with pertussis toxin (PTX) and an inhibitor of atypical PKCs. In addition, we demonstrate that apelin (65-77) also increases the enzymatic activity of p70S6K and that the effects of the previously mentioned inhibitors on the level of T389 phosphorylation correlate with their action on enzyme activity. Interestingly, the main findings were reproduced in umbilical endothelial cells and apelin (65-77) promoted thymidine incorporation into DNA of these cells, revealing that apelin is a new mitogenic peptide for the endothelial cell.
Masri
Bernard
B
Institut National de la Santé et de la Recherche Médicale INSERM U-589, C.H.U. Rangueil, Toulouse Cédex, France
Morin
Natacha
N
Cornu
Marion
M
Knibiehler
Bernard
B
Audigier
Yves
Y
D000818:Animals; D016466:CHO Cells; D002352:Carrier Proteins / Q000494:pharmacology*; D006224:Cricetinae; D003412:Cricetulus; D042783:Endothelial Cells / Q000187:drug effects / Q000201:enzymology; D004730:Endothelium, Vascular / Q000201:enzymology*; D004789:Enzyme Activation; D048049:Extracellular Signal-Regulated MAP Kinases / Q000037:antagonists & inhibitors; D005419:Flavonoids / Q000494:pharmacology; D006801:Humans; D008934:Mitogens / Q000494:pharmacology*; D037342:Pertussis Toxin / Q000494:pharmacology; D019869:Phosphatidylinositol 3-Kinases / Q000378:metabolism; D010766:Phosphorylation; D011493:Protein Kinase C / Q000502:physiology; D047428:Protein Kinase Inhibitors / Q000494:pharmacology; D017346:Protein Serine-Threonine Kinases / Q000378:metabolism; D011518:Proto-Oncogene Proteins / Q000378:metabolism; D051057:Proto-Oncogene Proteins c-akt; D038762:Ribosomal Protein S6 Kinases, 70-kDa / Q000378:metabolism*; D015398:Signal Transduction; D020123:Sirolimus / Q000494:pharmacology; D014470:Umbilical Cord / Q000166:cytology; D019061:src-Family Kinases / Q000378:metabolism
D002352:Carrier Proteins; D048049:Extracellular Signal-Regulated MAP Kinases; D005419:Flavonoids; D008934:Mitogens; D037342:Pertussis Toxin; D019869:Phosphatidylinositol 3-Kinases; D011493:Protein Kinase C; D047428:Protein Kinase Inhibitors; D017346:Protein Serine-Threonine Kinases; D011518:Proto-Oncogene Proteins; D051057:Proto-Oncogene Proteins c-akt; D038762:Ribosomal Protein S6 Kinases, 70-kDa; D020123:Sirolimus; D019061:src-Family Kinases; C494918:AKT1 protein, human; C093973:2-(2-amino-3-methoxyphenyl)-4H-1-benzopyran-4-one