EGF- and PDGF-stimulated phosphorylation in young and senescent WI-38 cells.
We have examined the ability of epidermal growth factor (EGF) and platelet-derived growth factor (PDGF) to stimulate cultures of young and senescent WI-38 cells to carry out tyrosine-specific phosphorylation of their respective membrane receptors. Previously we reported no reduction in EGF-stimulated phosphorylation in plasma membrane preparations of senescent cells. In this study we found no reduction in PDGF-stimulated phosphorylation in plasma membrane preparations from senescent cells. Furthermore, we found no differences in the EGF- or PDGF-stimulated phosphorylation of their respective receptors in intact cells. These data support the previous findings that although the EGF receptor autokinase activity becomes highly labile during extraction and immunoprecipitation of senescent cells, in situ loss of receptor tyrosine kinase activity is apparently not responsible for the age-associated loss of mitogenic responsiveness.
Gerhard
G S
GS
Wistar Institute of Anatomy and Biology, Philadelphia, Pennsylvania 19104.
Phillips
P D
PD
Cristofalo
V J
VJ
D001667:Binding, Competitive; D015153:Blotting, Western; D002460:Cell Line; D002462:Cell Membrane / Q000201:enzymology; D002470:Cell Survival / Q000502:physiology*; D004815:Epidermal Growth Factor / Q000502:physiology*; D006801:Humans; D007457:Iodine Radioisotopes; D007700:Kinetics; D010766:Phosphorylation; D010982:Platelet-Derived Growth Factor / Q000378:metabolism / Q000502:physiology*; D011505:Protein-Tyrosine Kinases / Q000378:metabolism; D011956:Receptors, Cell Surface / Q000378:metabolism; D017479:Receptors, Platelet-Derived Growth Factor
D007457:Iodine Radioisotopes; D010982:Platelet-Derived Growth Factor; D011956:Receptors, Cell Surface; D004815:Epidermal Growth Factor; D011505:Protein-Tyrosine Kinases; D017479:Receptors, Platelet-Derived Growth Factor