Nerve growth factor determines survival and death of PC12 cells by regulation of the bcl-x, bax, and caspase-3 genes.
We investigated the effects of nerve growth factor (NGF) and NGF withdrawal on expression of members of the bcl-2 family of genes and caspase-3 in PC12 cells. NGF regulated several members of the bcl-2 family and caspase-3 in a manner consistent with its effect on apoptosis in PC12 cells. Levels of bcl-xl, bcl-xs, and caspase-3 mRNAs were increased by NGF treatment. The increases in caspase-3 and bcl-xs levels should have disposed the cells toward apoptosis but were opposed by the simultaneous increase in bcl-xl level. NGF withdrawal resulted in abrupt down-regulation of bcl-xl and up-regulation of bax, favoring apoptosis. Forced expression of bcl-xl after NGF withdrawal was sufficient to prevent cell death. Cell death was rapid when NGF was withdrawn after 5 days of treatment but relatively slow when NGF was withdrawn after only 1 or 2 days of treatment. This was consistent with the reduced accumulation of caspase-3 mRNA with shorter NGF treatments. These results indicate that Bcl-xl, Bcl-xs, Bax, and caspase-3 are important regulators of apoptosis in PC12 cells. Furthermore, regulation of their mRNA levels is implicated in the signal transduction of NGF.
Rong
P
P
Department of Physiology, University of Melbourne, Parkville, Victoria, Australia.
Bennie
A M
AM
Epa
W R
WR
Barrett
G L
GL
D000818:Animals; D017209:Apoptosis / Q000187:drug effects / Q000502:physiology*; D053148:Caspase 3; D020169:Caspases / Q000235:genetics*; D002470:Cell Survival / Q000187:drug effects / Q000502:physiology*; D005786:Gene Expression Regulation / Q000187:drug effects*; D009414:Nerve Growth Factors / Q000494:pharmacology* / Q000502:physiology; D016716:PC12 Cells; D011518:Proto-Oncogene Proteins / Q000235:genetics*; D019253:Proto-Oncogene Proteins c-bcl-2 / Q000235:genetics*; D012333:RNA, Messenger / Q000378:metabolism; D051381:Rats; D020133:Reverse Transcriptase Polymerase Chain Reaction; D013997:Time Factors; D014158:Transcription, Genetic / Q000187:drug effects*; D051028:bcl-2-Associated X Protein; D051020:bcl-X Protein
C494828:Bax protein, rat; C494813:Bcl2l1 protein, rat; D009414:Nerve Growth Factors; D011518:Proto-Oncogene Proteins; D019253:Proto-Oncogene Proteins c-bcl-2; D012333:RNA, Messenger; D051028:bcl-2-Associated X Protein; D051020:bcl-X Protein; C505410:Casp3 protein, rat; D053148:Caspase 3; D020169:Caspases