Platelet-derived growth factor (PDGF)-induced Ca2+ signaling in the CG4 oligodendroglial cell line and in transformed oligodendrocytes expressing the beta-PDGF receptor.
Ca2+ signaling induced by platelet-derived growth factor (PDGF) was investigated in the oligodendroglial cell lines CG4 and CEINGE clone 3, using fura-2 microfluorimetry and video imaging. CEINGE cl3 cells, immortalized with polyoma middle T antigen, were found to uniformly express the polyoma middle T antigen protein as well as 2',3'-cyclic nucleotide 3'-phosphodiesterase, a specific marker for oligodendroglia. PDGF-BB induced both oscillatory and non-oscillatory Ca2+ responses in CEINGE cl3 cells as well as in CG4 cells, grown either as O-2A progenitors or differentiated oligodendrocytes. However, in CG4 cells the percentage of oscillatory Ca2+ responses was higher than that observed in CEINGE cl3 cells. In contrast, oscillatory Ca2+ responses were not observed in PC-12 cells transfected with beta-PDGF receptor (PDGFR) or in NIH 3T3 fibroblasts. CG4 cells expressed only the alpha-PDGFR, whereas CEINGE cl3 cells expressed both alpha and beta isoforms. When CEINGE cl3 cells were exposed to PDGF-AA, which binds only to the alpha-PDGFR, the percentage of oscillatory Ca2+ responses was higher than that observed after PDGF-BB stimulation. We previously reported that block of the enzyme sphingosine kinase, and a consequent increase in intracellular sphingosine levels in CEINGE cl3 cells caused an increase in the percentage of oscillatory Ca2+ responses induced by PDGF-BB. However, in CG4 cells block of sphingosine kinase did not increase the oscillatory Ca2+ response elicited by PDGF-BB, although the addition of exogenous sphingosine induced an oscillatory Ca2+ response in 77% of cells studied. We hypothesize that the alpha-PDGFR is less effective than the beta-PDGFR in stimulating the activity of sphingosine kinase. The results also suggest that alpha- and beta-PDGFRs may differently regulate sphingolipid metabolism.
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Department of Pharmacological and Physiological Sciences, The University of Chicago, Chicago, Illinois 60637, USA.
Miller
R J
RJ
D016475:3T3 Cells; D000818:Animals; D000077214:Becaplermin; D015153:Blotting, Western; D002118:Calcium / Q000378:metabolism*; D002460:Cell Line; D002461:Cell Line, Transformed; D002999:Clone Cells; D005455:Fluorescent Antibody Technique; D051379:Mice; D009355:Neomycin / Q000494:pharmacology; D009836:Oligodendroglia / Q000166:cytology / Q000378:metabolism*; D016716:PC12 Cells; D010982:Platelet-Derived Growth Factor / Q000494:pharmacology*; D020574:Proto-Oncogene Proteins c-sis; D051381:Rats; D020797:Receptor, Platelet-Derived Growth Factor beta; D017479:Receptors, Platelet-Derived Growth Factor / Q000235:genetics / Q000378:metabolism*; D015398:Signal Transduction; D013110:Sphingosine / Q000031:analogs & derivatives / Q000494:pharmacology
D010982:Platelet-Derived Growth Factor; D020574:Proto-Oncogene Proteins c-sis; C075278:platelet-derived growth factor A; D000077214:Becaplermin; D020797:Receptor, Platelet-Derived Growth Factor beta; D017479:Receptors, Platelet-Derived Growth Factor; D009355:Neomycin; D013110:Sphingosine; D002118:Calcium