Serum depletion increases the neurofilament protein mRNA levels in a neuroblastoma cell line, GOTO.
A human neuroblastoma cell line, GOTO, extends neurite-like processes upon withdrawal of serum from culture medium. This morphological change was accompanied by a 5-fold increase in the neurofilament (NF)-L and a 10-fold increase in the NF-M mRNA levels after 24 h. The addition of a protein kinase inhibitor, H-7 (1-(5-isoquinolinesulfonyl)-2-methylpiperazine dihydrochloride) also induced the extension of neurite-like processes; however, it did not increase the NF mRNA levels. Thrombin inhibited the extension of neurite-like processes in serum-free culture without affecting the increase in the NF mRNA levels. There was no difference in the number of cells progressing through the S phase between serum-containing and -free cultures at 24 h. This indicates that the increase in the NF mRNA levels upon withdrawal of serum was not preceded by the growth arrest. Treatment with actinomycin D and cycloheximide inhibited the increase in the NF mRNA levels. The half life of the NF gene transcripts was prolonged in the serum-free condition. These results indicate that the serum depletion-induced increase in the NF-L and -M mRNA levels was regulated by both transcriptional and post-transcriptional mechanisms, and the increase in the expression of the NF genes was not simply mediated by growth arrest but controlled by unknown regulator proteins.
Department of Pediatrics, Kobe University School of Medicine, Japan.
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Tsuneishi
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Sano
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Nakamura
D002455:Cell Division / Q000187:drug effects; D016895:Culture Media, Serum-Free / Q000494:pharmacology*; D003513:Cycloheximide / Q000494:pharmacology; D003609:Dactinomycin / Q000494:pharmacology; D015972:Gene Expression Regulation, Neoplastic / Q000187:drug effects; D006133:Growth Substances / Q000502:physiology*; D006801:Humans; D009363:Neoplasm Proteins / Q000096:biosynthesis* / Q000235:genetics; D009447:Neuroblastoma; D016900:Neurofilament Proteins / Q000096:biosynthesis* / Q000235:genetics; D009474:Neurons / Q000378:metabolism*; D014176:Protein Biosynthesis / Q000187:drug effects; D012333:RNA, Messenger / Q000096:biosynthesis*; D012334:RNA, Neoplasm / Q000096:biosynthesis*; D016196:S Phase; D014158:Transcription, Genetic / Q000187:drug effects; D014407:Tumor Cells, Cultured
D016895:Culture Media, Serum-Free; D006133:Growth Substances; D009363:Neoplasm Proteins; D016900:Neurofilament Proteins; D012333:RNA, Messenger; D012334:RNA, Neoplasm; C044882:neurofilament protein L; C061195:neurofilament protein M; D003609:Dactinomycin; D003513:Cycloheximide