NF-kappaB-mediated up-regulation of Bcl-X(S) and Bax contributes to cytochrome c release in cyanide-induced apoptosis

J Neurochem. 2002 May;81(4):842-52. doi: 10.1046/j.1471-4159.2002.00880.x.


Cyanide induces apoptosis through cytochrome c activated caspase cascade in primary cultured cortical neurons. The underlying mechanism for cytochrome c release from mitochondria after cyanide treatment is still unclear. In this study, the roles of endogenous Bcl-2 proteins in cyanide-induced apoptosis were investigated. After cyanide (100-500 microm) treatment for 24 h, two pro-apoptotic Bcl-2 proteins, Bcl-X(S) and Bax were up-regulated as shown by western blot and RT-PCR analysis. The expression levels of two antiapoptotic Bcl-2 proteins, Bcl-2 and Bcl-X(L), remained unchanged after cyanide treatment, whereas the mRNA levels of Bcl-X(S) and Bax began to increase within 2 h and their protein levels increased 6 h after treatment. NF-kappaB, a redox-sensitive transcription factor activated after cyanide treatment, is responsible for the up-regulation of Bcl-X(S) and Bax. SN50, which is a synthetic peptide that blocks translocation of NF-kappaB from cytosol to nucleus, inhibited the up-regulation of Bcl-X(S) and Bax. Similar results were obtained using a specific kappaB decoy DNA. NMDA receptor activation and reactive oxygen species (ROS) generation are upstream events of NF-kappaB activation, as blockade of these two events by MK801, l-NAME or PBN inhibited cyanide-induced up-regulation of Bcl-X(S) and Bax. Up-regulation of pro-apoptotic Bcl-X(S) and Bax contributed to cyanide-induced cytochrome c release, because SN50 and a specific Bax antisense oligodeoxynucleotide significantly reduced release of cytochrome c from mitochondria as shown by western blot analysis. It was concluded that NF-kappaB-mediated up-regulation of Bcl-X(S) and Bax is involved in regulating cytochrome c release in cyanide-induced apoptosis.

Publication types

  • Research Support, U.S. Gov't, P.H.S.

MeSH terms

  • Animals
  • Apoptosis* / drug effects
  • Blotting, Western
  • Caspases / metabolism
  • Cyanides / toxicity*
  • Cytochrome c Group / metabolism*
  • DNA Fragmentation
  • Enzyme Inhibitors / pharmacology
  • Mitochondria / drug effects
  • Mitochondria / metabolism
  • NF-kappa B / antagonists & inhibitors
  • NF-kappa B / metabolism*
  • Neurons / cytology
  • Neurons / drug effects
  • Neurons / metabolism
  • Oligonucleotides, Antisense / pharmacology
  • Oxidation-Reduction
  • Peptides / pharmacology
  • Proto-Oncogene Proteins / antagonists & inhibitors
  • Proto-Oncogene Proteins / genetics
  • Proto-Oncogene Proteins / metabolism*
  • Proto-Oncogene Proteins c-bcl-2 / genetics
  • Proto-Oncogene Proteins c-bcl-2 / metabolism*
  • RNA, Messenger / metabolism
  • Rats
  • Rats, Sprague-Dawley
  • Reverse Transcriptase Polymerase Chain Reaction
  • Up-Regulation / drug effects
  • bcl-2-Associated X Protein
  • bcl-X Protein


  • Bax protein, rat
  • Bcl2l1 protein, rat
  • Cyanides
  • Cytochrome c Group
  • Enzyme Inhibitors
  • NF-kappa B
  • Oligonucleotides, Antisense
  • Peptides
  • Proto-Oncogene Proteins
  • Proto-Oncogene Proteins c-bcl-2
  • RNA, Messenger
  • SN50 peptide
  • bcl-2-Associated X Protein
  • bcl-X Protein
  • Caspases