Repeated electroconvulsive seizure induces c-Myc down-regulation and Bad inactivation in the rat frontal cortex

Exp Mol Med. 2008 Aug 31;40(4):435-44. doi: 10.3858/emm.2008.40.4.435.

Abstract

Repeated electroconvulsive seizure (ECS), a model for electroconvulsive therapy (ECT), exerts neuroprotective and proliferative effects in the brain. This trophic action of ECS requires inhibition of apoptotic activity, in addition to activation of survival signals. c-Myc plays an important role in apoptosis of neurons, in cooperation with the Bcl-2 family proteins, and its activity and stability are regulated by phosphorylation and ubiquitination. We examined c-Myc and related proteins responsible for apoptosis after repeated ECS. In the rat frontal cortex, repeated ECS for 10 days reduced the total amount of c-Myc, while increasing phosphorylation of c-Myc at Thr58, which reportedly induces degradation of c-Myc. As expected, ubiquitination of both phosphorylated and total c-Myc increased after 10 days ECS, suggesting that ECS may reduce c-Myc protein level via ubiquitination-proteasomal degradation. Bcl-2 family proteins, caspase, and poly(ADP-ribose) polymerase (PARP) were investigated to determine the consequence of down-regulating c-Myc. Protein levels of Bcl-2, Bcl-X(L), Bax, and Bad showed no change, and cleavage of caspase-3 and PARP were not induced. However, phosphorylation of Bad at Ser-155 and binding of Bad to 14-3-3 increased without binding to Bcl-X(L) after repeated ECS, implying that repeated ECS sequesters apoptotic Bad and frees pro-survival Bcl-XL. Taken together, c-Myc down-regulation via ubiquitination-proteasomal degradation and Bad inactivation by binding to 14-3-3 may be anti-apoptotic mechanisms elicited by repeated ECS in the rat frontal cortex. This finding further supports the trophic effect of ECS blocking apoptosis as a possible therapeutic effect of ECT.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • 14-3-3 Proteins / metabolism
  • Animals
  • Down-Regulation
  • Electroconvulsive Therapy / adverse effects*
  • Frontal Lobe / metabolism*
  • Male
  • Models, Biological
  • Neurons / metabolism
  • Periodicity
  • Phosphorylation
  • Protein Binding
  • Protein Processing, Post-Translational
  • Proto-Oncogene Proteins c-bcl-2 / metabolism
  • Proto-Oncogene Proteins c-myc / metabolism*
  • Rats
  • Rats, Sprague-Dawley
  • Seizures / etiology
  • Seizures / metabolism*
  • Tumor Cells, Cultured
  • Ubiquitination
  • bcl-Associated Death Protein / antagonists & inhibitors
  • bcl-Associated Death Protein / metabolism*

Substances

  • 14-3-3 Proteins
  • Bad protein, rat
  • Proto-Oncogene Proteins c-bcl-2
  • Proto-Oncogene Proteins c-myc
  • bcl-Associated Death Protein