title: c-fos proto-oncogene expression in astrocytes associated with differentiation or proliferation but not depolarization.
abstract: Expression of the c-fos proto-oncogene in rat neocortical astrocytes in culture was examined using Northern blotting and immunocytochemistry. Marked induction of c-fos mRNA in astrocytes was observed after treatment with epidermal growth factor (EGF), basic fibroblast growth factor (bFGF), dibutyryl cyclic AMP (db-cAMP), and phorbol diester (TPA; 12-O-tetra-decanoylphorbol 13-acetate), which are known to induce the proliferation or differentiation of astrocytes. Increase of c-fos protein immunoreactivity (IR) was obtained after treatment with fetal calf serum, EGF, bFGF, db-cAMP and TPA. High concentrations of calcium ionophore A23187, which were lethal to cultured astrocytes, also increased c-fos protein-IR. Treatment with lower concentrations of calcium ionophore (which slightly increase Ca2+ uptake), high K+ and nerve growth factor had no detectable effect on c-fos expression. These results show that depolarization does not induce c-fos in astrocytes and suggest that c-fos may play a role in differentiation and proliferation of astrocytes.
authors.affiliation: Department of Neurology, University of California, San Francisco.
authors.forename: K
authors.initials: K
authors.lastname: Hisanaga
authors.forename: S M
authors.initials: SM
authors.lastname: Sagar
authors.forename: K J
authors.initials: KJ
authors.lastname: Hicks
authors.forename: R A
authors.initials: RA
authors.lastname: Swanson
authors.forename: F R
authors.initials: FR
authors.lastname: Sharp
mesh_terms: D000818:Animals; D001253:Astrocytes / Q000166:cytology / Q000187:drug effects / Q000378:metabolism*; D002454:Cell Differentiation; D002455:Cell Division; D002478:Cells, Cultured; D005786:Gene Expression Regulation / Q000502:physiology*; D006133:Growth Substances / Q000494:pharmacology; D007150:Immunohistochemistry; D008934:Mitogens / Q000494:pharmacology; D011518:Proto-Oncogene Proteins / Q000235:genetics* / Q000378:metabolism; D016760:Proto-Oncogene Proteins c-fos; D012333:RNA, Messenger / Q000235:genetics* / Q000378:metabolism; D051381:Rats; D011919:Rats, Inbred Strains
chemical_list: D006133:Growth Substances; D008934:Mitogens; D011518:Proto-Oncogene Proteins; D016760:Proto-Oncogene Proteins c-fos; D012333:RNA, Messenger