N-methyl-D-aspartate receptor-dependent and -independent cytotoxic effects of Dictyostelium discoideum differentiation-inducing factor-1 on rat cortical neurons.
Differentiation-inducing factor-1 (DIF-1) is a chlorinated alkylphenone (small lipophilic hormone) that induces stalk cell formation in the cellular slime mold Dictyostelium discoideum. Recent studies have revealed that DIF-1 inhibits growth and induces the differentiation of mammalian tumor cells. The present study examines the effects of DIF-1 on rat cortical neurons in primary culture. We found that DIF-1 induced rapid neuronal cell death. The release of lactate dehydrogenase (LDH), as an indicator of cell death, increased dose-dependently with DIF-1. The release of LDH was inhibited by the N-methyl-D-aspartate (NMDA) receptor antagonists MK801 and AP5, suggesting that the NMDA receptor is involved in the induction of cell death by DIF-1. However, glutamate cytotoxicity could not explain the entire action of DIF-1 on neurons because the estimated concentration of glutamate around DIF-1-treated neurons was below 50 microM and DIF-1 caused more severe cell death than 500 microM glutamate. We discovered that another portion of DIF-1 cytotoxicity is independent of the NMDA receptor; that is, coaddition of DIF-1 and MK801 induced dendritic beading and increased expression of the immediate early genes c-fos and zif/268. These results indicate that DIF-1 induces rapid cell death via both NMDA receptor-dependent and -independent pathways in rat cortical neurons.
Kanno
T
T
Laboratory of Molecular and Cellular Morphology, Institute for Molecular and Cellular Regulation, Gunma University, 3-39-15, Showamachi, Maebashi, Gunma 371-8512, Japan.
Kubohara
Y
Y
Goto
F
F
Takata
K
K
Hayashi
K
K
D000818:Animals; D001483:Base Sequence; D002470:Cell Survival / Q000187:drug effects / Q000502:physiology; D002478:Cells, Cultured; D002540:Cerebral Cortex / Q000166:cytology* / Q000201:enzymology; D017931:DNA Primers; D004023:Dictyostelium / Q000378:metabolism*; D018698:Glutamic Acid / Q000494:pharmacology; D006588:Hexanones / Q000494:pharmacology*; D007770:L-Lactate Dehydrogenase / Q000378:metabolism; D009474:Neurons / Q000166:cytology* / Q000201:enzymology; D051381:Rats; D016194:Receptors, N-Methyl-D-Aspartate / Q000502:physiology*; D020133:Reverse Transcriptase Polymerase Chain Reaction
D017931:DNA Primers; D006588:Hexanones; D016194:Receptors, N-Methyl-D-Aspartate; C053433:1-((3,5-dichloro)-2,6-dihydroxy-4-methoxyphenyl)-1-hexanone; D018698:Glutamic Acid; D007770:L-Lactate Dehydrogenase