Expression of the proto-oncogene c-fos in three-dimensional fetal brain cell cultures and the lack of correlation with maturation-inducing stimuli.
Previous work has shown that aggregating fetal brain cell cultures are able to attain a highly differentiated state, and that their development is greatly enhanced by growth and/or differentiation factors such as epidermal growth factor (EGF), basic fibroblast growth factor (bFGF), and the protein kinase C-activating tumor promoter mezerein. The present study shows that in these 3-dimensional cultures the peptide growth factors EGF and bFGF as well as mezerein are able to induce the expression of the proto-oncogene c-fos. This induction was rapid and transient, in good agreement with observations reported from a wide variety of cell types in vitro. The maximal levels of c-fos mRNA found after stimulation were low in immature cultures and increased greatly as maturation progressed. Of the three factors tested, mezerein was the most potent inducer of c-fos. In contrast to the peptide growth factors EGF and bFGF which were found to induce c-fos only in glial cells, mezerein was stimulatory in glial cells as well as in neurons. A similar cell type specificity has been observed previously for the maturation-enhancing response in immature aggregate cultures. However, in the present study no correlation was found between the degree of c-fos induction and the extent of the maturation-enhancing stimulation. Immature cultures known to be most sensitive and responsive to these maturation-enhancing agents required relatively high doses of peptide growth factors for the induction of c-fos, and the maximal levels of c-fos mRNA elicited were much lower than those in differentiated cultures which did not show any long-term response to these stimuli.(ABSTRACT TRUNCATED AT 250 WORDS)
Bardoscia
M T
MT
Institute of Physiology, University of Lausanne, Switzerland.
Amstad
P
P
Honegger
P
P
D015124:8-Bromo Cyclic Adenosine Monophosphate / Q000494:pharmacology; D000818:Animals; D002454:Cell Differentiation; D002478:Cells, Cultured; D003561:Cytarabine / Q000494:pharmacology; D004224:Diterpenes; D004815:Epidermal Growth Factor / Q000494:pharmacology; D005333:Fetus; D016222:Fibroblast Growth Factor 2 / Q000494:pharmacology; D015870:Gene Expression / Q000187:drug effects; D016762:Genes, fos / Q000187:drug effects; D009474:Neurons / Q000187:drug effects / Q000502:physiology; D012313:RNA / Q000235:genetics / Q000302:isolation & purification; D012333:RNA, Messenger / Q000235:genetics / Q000302:isolation & purification / Q000378:metabolism; D051381:Rats; D011919:Rats, Inbred Strains; D011994:Recombinant Proteins / Q000494:pharmacology; D013687:Telencephalon / Q000196:embryology / Q000502:physiology*; D013729:Terpenes / Q000494:pharmacology
D004224:Diterpenes; D012333:RNA, Messenger; D011994:Recombinant Proteins; D013729:Terpenes; D003561:Cytarabine; D016222:Fibroblast Growth Factor 2; D015124:8-Bromo Cyclic Adenosine Monophosphate; C011309:mezerein; D004815:Epidermal Growth Factor; D012313:RNA