A novel role for glyceraldehyde-3-phosphate dehydrogenase and monoamine oxidase B cascade in ethanol-induced cellular damage.
BACKGROUND
Alcoholism is a major psychiatric condition at least partly associated with ethanol (EtOH)-induced cell damage. Although brain cell loss has been reported in subjects with alcoholism, the molecular mechanism is unclear. Glyceraldehyde-3-phosphate dehydrogenase (GAPDH) and monoamine oxidase B (MAO B) reportedly play a role in cellular dysfunction under stressful conditions and might contribute to EtOH-induced cell damage.


METHODS
Expression of GAPDH and MAO B protein was studied in human glioblastoma and neuroblastoma cell lines exposed to physiological concentrations of EtOH. Expression of these proteins was also examined in the prefrontal cortex from human subjects with alcohol dependence and in rats fed with an EtOH diet. Coimmunoprecipitation, subcellular fractionation, and luciferase assay were used to address nuclear GAPDH-mediated MAO B activation. To test the effects of inactivation, RNA interference and pharmacological intervention were used, and cell damage was assessed by terminal deoxynucleotidyl transferase (TdT)-mediated dUTP Nick End Labeling (TUNEL) and hydrogen peroxide measurements.


RESULTS
Ethanol significantly increases levels of GAPDH, especially nuclear GAPDH, and MAO B in neuronal cells as well as in human and rat brains. Nuclear GAPDH interacts with the transcriptional activator, transforming growth factor-beta-inducible early gene 2 (TIEG2), and augments TIEG2-mediated MAO B transactivation, which results in cell damage in neuronal cells exposed to EtOH. Knockdown expression of GAPDH or treatment with MAO B inhibitors selegiline (deprenyl) and rasagiline (Azilect) can block this cascade.


CONCLUSIONS
Ethanol-elicited nuclear GAPDH augments TIEG2-mediated MAO B, which might play a role in brain damage in subjects with alcoholism. Compounds that block this cascade are potential candidates for therapeutic strategies.
Ou
Xiao-Ming
XM
Department of Psychiatry and Human Behavior, University of Mississippi Medical Center, Jackson, Mississippi 39216, USA. xou@psychiatry.umsmed.edu
Stockmeier
Craig A
CA
Meltzer
Herbert Y
HY
Overholser
James C
JC
Jurjus
George J
GJ
Dieter
Lesa
L
Chen
Kevin
K
Lu
Deyin
D
Johnson
Chandra
C
Youdim
Moussa B H
MB
Austin
Mark C
MC
Luo
Jia
J
Sawa
Akira
A
May
Warren
W
Shih
Jean C
JC
D000437:Alcoholism / Q000473:pathology*; D000704:Analysis of Variance; D000818:Animals; D051017:Apoptosis Regulatory Proteins; D018797:Cell Cycle Proteins / Q000378:metabolism; D045744:Cell Line, Tumor; D002492:Central Nervous System Depressants / Q000009:adverse effects*; D000431:Ethanol / Q000009:adverse effects*; D005786:Gene Expression Regulation / Q000187:drug effects* / Q000235:genetics; D005909:Glioblastoma; D005987:Glyceraldehyde-3-Phosphate Dehydrogenases / Q000235:genetics / Q000378:metabolism*; D006801:Humans; D006861:Hydrogen Peroxide / Q000378:metabolism; D047468:Immunoprecipitation / Q000379:methods; D020287:In Situ Nick-End Labeling / Q000379:methods; D008297:Male; D008995:Monoamine Oxidase / Q000235:genetics / Q000378:metabolism*; D008996:Monoamine Oxidase Inhibitors / Q000494:pharmacology; D009447:Neuroblastoma; D009474:Neurons / Q000187:drug effects / Q000378:metabolism; D017397:Prefrontal Cortex / Q000187:drug effects / Q000378:metabolism; D012333:RNA, Messenger / Q000378:metabolism; D051381:Rats; D017208:Rats, Wistar; D012097:Repressor Proteins / Q000378:metabolism; D012642:Selegiline / Q000494:pharmacology; D014162:Transfection / Q000379:methods
D051017:Apoptosis Regulatory Proteins; D018797:Cell Cycle Proteins; D002492:Central Nervous System Depressants; C115117:KLF11 protein, human; D008996:Monoamine Oxidase Inhibitors; D012333:RNA, Messenger; D012097:Repressor Proteins; D012642:Selegiline; D000431:Ethanol; D006861:Hydrogen Peroxide; D005987:Glyceraldehyde-3-Phosphate Dehydrogenases; D008995:Monoamine Oxidase