Decorin-mediated signal transduction in endothelial cells. Involvement of Akt/protein kinase B in up-regulation of p21(WAF1/CIP1) but not p27(KIP1).
Endothelial cells undergoing angiogenesis express decorin, a small multifunctional proteoglycan. We have shown that decorin is causally involved in the formation of capillary-like structures and a decrease in apoptosis in endothelial cells cultured in a collagen lattice. Here we investigate signal transduction pathways mediating the effects of decorin. Reverse transcription-polymerase chain reaction demonstrated that p21 and p27, two inhibitors of cyclin-dependent kinases, were up-regulated by decorin induction. Decorin also increased protein levels of p21 and caused its translocation into the nucleus. p21 synthesis started 6 h after decorin addition and reached a plateau after 18 h, while cyclin A, which was also induced, peaked at 12 h and declined below basal levels within 24 h. These effects were mediated by the Akt/protein kinase B pathway. Akt phosphorylation at Thr-308 increased 4-fold and at Ser-473 1.4-fold within 10 min after decorin addition. Overexpression of dominant negative Akt inhibited the decorin-mediated induction of p21 and cyclin A, but had no effect on p27. These results show that decorin is a signaling molecule in sprouting endothelial cells where it acts via different pathways, one of them involving Akt/protein kinase B.
Schönherr
E
E
Institute of Physiological Chemistry and Pathobiochemistry, Münster, D-48149 Germany. schonhe@uni-muenster.de
Levkau
B
B
Schaefer
L
L
Kresse
H
H
Walsh
K
K
D001483:Base Sequence; D018797:Cell Cycle Proteins / Q000378:metabolism*; D002460:Cell Line; D050759:Cyclin-Dependent Kinase Inhibitor p21; D050760:Cyclin-Dependent Kinase Inhibitor p27; D016213:Cyclins / Q000378:metabolism*; D017931:DNA Primers; D058575:Decorin; D004727:Endothelium / Q000166:cytology / Q000201:enzymology / Q000378:metabolism*; D016326:Extracellular Matrix Proteins; D006801:Humans; D010766:Phosphorylation; D017346:Protein Serine-Threonine Kinases; D011509:Proteoglycans / Q000502:physiology*; D011518:Proto-Oncogene Proteins / Q000378:metabolism*; D051057:Proto-Oncogene Proteins c-akt; D020133:Reverse Transcriptase Polymerase Chain Reaction; D015398:Signal Transduction / Q000502:physiology*; D025521:Tumor Suppressor Proteins / Q000378:metabolism*; D015854:Up-Regulation
C493956:CDKN1A protein, human; D018797:Cell Cycle Proteins; D050759:Cyclin-Dependent Kinase Inhibitor p21; D016213:Cyclins; C546878:DCN protein, human; D017931:DNA Primers; D058575:Decorin; D016326:Extracellular Matrix Proteins; D011509:Proteoglycans; D011518:Proto-Oncogene Proteins; D025521:Tumor Suppressor Proteins; D050760:Cyclin-Dependent Kinase Inhibitor p27; C494918:AKT1 protein, human; D017346:Protein Serine-Threonine Kinases; D051057:Proto-Oncogene Proteins c-akt