A Novel Role for Glyceraldehyde-3-Phosphate Dehydrogenase and Monoamine Oxidase B Cascade in Ethanol-Induced Cellular Damage

Abstract

Background Alcoholism is a major psychiatric condition at least partly associated with ethanol-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 may contribute to ethanol-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 ethanol. Expression of these proteins was also examined in the prefrontal cortex from human subjects with alcohol dependence and in rats fed with an ethanol diet. Co-immunoprecipitation, subcellular fractionation, and luciferase assay were used to address nuclear GAPDH-mediated MAO B activation. To test the effects of inactivation, RNAi and pharmacological intervention were used, and cell damage was assessed by TUNEL and H2O2 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 ethanol. 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 may play a role in brain damage in subjects with alcoholism. Compounds that block this cascade are potential candidates for therapeutic strategies.

Mechanistic Role for a Novel Glucocorticoid-KLF11 (TIEG2) Protein Pathway in Stress-induced Monoamine Oxidase A Expression

“…Notably, the translocation of KLF11 into the nucleus parallels the nuclear translocation of the multifunctional protein GAPDH, which has been implicated in cellular apoptosis (44,45). KLF11 has been shown to associate intranuclearly with GAPDH and to promote neuronal cell degeneration and death via the GAPDH-KLF11-MAO B cascade (23,34). This interaction may also occur in the cytosol, similar to the complex of the ubiquitin ligase Siah1 and GAPDH (45,46).…”

“…After transfer, the membranes were probed with primary and secondary antibodies. All band intensities were normalized to those of ␤-actin using Quantity One analysis software (8,23).…”

“…It is currently better known because of its role in metabolism. Indeed, publications from our group demonstrate that KLF11 (TIEG2) regulates genes involved in the metabolism of lipids, glucose, prostaglandins, neurotransmitters, and alcohol/drugs (23)(24)(25). We have also published that KLF11 is linked to three types of diabetes (a metabolic disease) (26 -28).…”

The Reduction of R1, a Novel Repressor Protein for Monoamine Oxidase A, in Major Depressive Disorder

“…While one problematic implication for elevated MAO A levels is excessive catalysis of neurotransmitters (Goridis and Neff, 1971), a second problematic implication for elevated MAO A is that as MAO A degrades these neurotransmitters, reactive oxygen species such as hydrogen peroxide (H 2 O 2 ) are produced, and these reactive oxygen species may lead to apoptotic cell death (De Zutter and Davis, 2001;Ou et al, 2009b;Youdim and Bakhle, 2006;Youdim et al, 2004). In vitro studies suggest that mitochondrial dysfunction and apoptotic cell death may be induced by MAO-dependent H 2 O 2 production (Kunduzova et al, 2002).…”

Role of Apoptosis Signal-regulating Kinase 1 (ASK1) as an Activator of the GAPDH-Siah1 Stress-Signaling Cascade

“…Glyceraldehyde-3-phosphate dehydrogenase (GAPDH) 3 is a key enzyme in glycolysis, and so plays a major role in cellular energy supply (9). In addition to this classic concept, GAPDH is involved in many subcellular processes that include; DNA repair (10), membrane fusion, and transport (11), tRNA export (12), and cell death (13)(14)(15)(16)(17)(18)(19). The functional diversity of GAPDH is largely regulated by its subcellular localization and post-translational modifications (20).…”