Protein phosphorylation in response to PDGF stimulation in cultured neurons and astrocytes.
Platelet-derived growth factor (PDGF) is an important growth factor for a variety of cells, including neurons and glial cells. PDGF signal transduction pathways have been studied primarily in mesenchyme-derived cells (such as fibroblasts and smooth muscle cells). However, little is known about these pathways in the central nervous system (CNS). It is believed that phosphorylation is a critical aspect of several steps in the signal transduction pathway. In this study, neurons and type 1 astrocytes in vitro were radiolabeled with 32P-orthophosphate (32P-Pi). The cells were lysed, and labeled proteins were separated by two-dimensional gel electrophoresis. Autoradiograms of PDGF-stimulated and control samples were compared. We found that in neurons and type 1 astrocytes in vitro, PDGF-BB greatly enhances protein phosphorylation while PDGF-AA has less of an effect on protein phosphorylation. Furthermore, because PDGF signal transduction pathways are likely to affect the cytoskeleton, we studied changes in actin-binding proteins induced by PDGF-BB. We found that PDGF-BB alters the expression, migration pattern and/or avidity of some actin-binding proteins in neurons. In conclusion, protein phosphorylation is up-regulated by PDGF in mouse cortical neurons and type 1 astrocytes in vitro. PDGF's effects on phosphorylation of cytoskeletal proteins might be a important mechanism by which PDGF affects the development and normal functions of central nervous system cells.
Zhang
F X
FX
Department of Anatomy, University of Mississippi Medical Center, Jackson 39216-4500, USA.
Hutchins
J B
JB
D000818:Animals; D000925:Anticoagulants / Q000494:pharmacology*; D001253:Astrocytes / Q000737:chemistry / Q000187:drug effects / Q000378:metabolism*; D001345:Autoradiography; D000077214:Becaplermin; D015153:Blotting, Western; D002478:Cells, Cultured; D002540:Cerebral Cortex / Q000166:cytology; D003598:Cytoskeletal Proteins / Q000378:metabolism; D015180:Electrophoresis, Gel, Two-Dimensional; D005260:Female; D051379:Mice; D008810:Mice, Inbred C57BL; D008840:Microfilament Proteins / Q000378:metabolism; D009474:Neurons / Q000737:chemistry / Q000187:drug effects / Q000201:enzymology*; D010750:Phosphoproteins / Q000032:analysis / Q000276:immunology; D010766:Phosphorylation; D010982:Platelet-Derived Growth Factor / Q000494:pharmacology*; D011233:Precipitin Tests; D011247:Pregnancy; D020574:Proto-Oncogene Proteins c-sis; D017479:Receptors, Platelet-Derived Growth Factor / Q000378:metabolism; D015398:Signal Transduction / Q000187:drug effects / Q000502:physiology; D000099149:Ezrin
D000925:Anticoagulants; D000077214:Becaplermin; D003598:Cytoskeletal Proteins; D008840:Microfilament Proteins; D010750:Phosphoproteins; D010982:Platelet-Derived Growth Factor; D020574:Proto-Oncogene Proteins c-sis; D017479:Receptors, Platelet-Derived Growth Factor; D000099149:Ezrin; C075278:platelet-derived growth factor A