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.
Tsuneishi
S
S
Department of Pediatrics, Kobe University School of Medicine, Japan.
Sano
K
K
Nakamura
H
H
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