PDGF-AA effectively stimulates early events but has no mitogenic activity in AKR-2B mouse fibroblasts.
The response of AKR-2B mouse fibroblasts, which express approximately equal numbers of platelet-derived growth factor (PDGF)-alpha and -beta receptors on their surface (V. Hoppe et al. Eur. J. Biochem. 187, 207-214, 1990) to all three isoforms of PDGF, was studied. All isoforms stimulated early events, i.e., receptor autophosphorylation on tyrosine, total cellular phosphorylation, increase in 32P-labeled phospholipid content, but there was no correlation between the extents measured for the different effects. Although rPDGF-AA effectively stimulated these early events, it was unable to induce [3H]thymidine incorporation and cell growth whereas rPDGF-BB and -AB stimulated the division of more than 90% of the cells. This activity was restored by addition of insulin-like growth factor I (IGF-I), which itself exhibited only a low mitogenic activity. rPDGF-AB or -BB did not require the presence of IGF-I to fully stimulate cells for [3H]thymidine incorporation and cell division. Apparently, rPDGF-AA induced only a "competence" state of the cells whereas rPDGF-AB or -BB was also able to initiate "progression". It is speculated that some early events occurring during the competence phase might be part of a "maintenance" program elicited by growth factors.
Simm
A
A
Theodor-Boveri-Institut für Biowissenschaften (Biozentrum) der Universität, Würzburg, Germany.
Hoppe
V
V
Tatje
D
D
Schenzinger
A
A
Hoppe
J
J
D000818:Animals; D002453:Cell Cycle / Q000187:drug effects; D002478:Cells, Cultured / Q000187:drug effects; D005347:Fibroblasts / Q000166:cytology / Q000187:drug effects*; D051379:Mice; D008806:Mice, Inbred AKR; D008938:Mitosis / Q000187:drug effects; D008954:Models, Biological; D010743:Phospholipids / Q000378:metabolism; D010766:Phosphorylation / Q000187:drug effects; D010982:Platelet-Derived Growth Factor / Q000737:chemistry / Q000494:pharmacology*; D011956:Receptors, Cell Surface / Q000378:metabolism; D017479:Receptors, Platelet-Derived Growth Factor; D014443:Tyrosine / Q000187:drug effects / Q000378:metabolism
D010743:Phospholipids; D010982:Platelet-Derived Growth Factor; D011956:Receptors, Cell Surface; D014443:Tyrosine; D017479:Receptors, Platelet-Derived Growth Factor