Neuroprotective Effects Of ALDH2 Gene In Cultured Hippocampal Neurons

Background:4-Hydroxynonenal (4-HNE) is an important marker of oxidative stress in Alzheimer's disease (AD) and other neurodegenerative diseases, which can also accumulate in these diseases. Numerous studies show that 4-HNE neurotoxicity includes inhibition of neurite growth, damaging the nervous microtubules and neuronal tubulin; 4-HNE can also act directly on the receptor or the catalytic protein signaling pathway, change the protein signal transduction mechanisms which can lead to neuronal apoptosis; 4-HNE can also cause mitochondrial oxidative stress reactions.4-HNE may play an important role in the development process of neurodegenerative diseases, so treatments against the neurotoxicity of 4-HNE may be a therapeutic target for neurodegenerative diseases. Mitochondrial aldehyde dehydrogenase (aldehyde dehydrogenase-2, ALDH2) is a nuclear encoded mitochondrial enzyme, which is located in the mitochondrial matrix. ALDH2 is widely expressed in the central nervous system, but its functions in the central nervous system and roles in central nervous system-related diseases are still uncertain. We are not sure of the intrinsic link between 4-HNE and ALDH2, however ALDH2 plays a key role in the metabolism of aldehydes, so we assume that overexpression of ALDH2 could inhibit 4-HNE-induced neuronal injury and neuronal apoptosis processes, the purpose of treating neurodegenerative diseases achieved. Objective:we transfect ALDH2 gene in primary hippocampal neurons, and study the neuroprotective effects of ALDH2 and its mechanisms. Methods:we construct pEGFP-N2 vector containing ALDH2 cDNA, we use electroporation method to transfect ALDH2 cDNA into primary hippocampal neurons at the cellular level. We use Western blot, immunohistochemistry and immunofluorescence staining, real-time quantitative reverse transcription polymerase chain reaction, kinase activity assay, MTT assay, immunoprecipitation, and Axiovision software analysis method to detect over-expression of ALDH2 that can block 4HNE and reduce neurotoxicity. Results:(1) in cultured primary hippocampal neurons, ALDH2 gene transfection effectively improved ALDH2 ALDH2 mRNA expression and fusion protein expression; (2) ALDH2 gene transfection effectively reversed the 4-HNE-induced nerve neurite injury; (3) ALDH2 gene transfection can increase neuronal survival, effectively reversed the 4-HNE-induced neuronal cell death; (4) ALDH2 gene transfection can decrease casepase-3 and Bax activity, effectively reversing the 4-HNE-induced neuronal apoptosis; (5) In cultured primary hippocampal neurons, ALDH2 gene transfection effectively reverse the 4-HNE induced oxidative stress by inhibiting mitochondrial membrane potential decrease and reducing neuronal ROS level. Conclusions:ALDH2 gene transfection not only inhibits the neurotoxicity of 4-HNE but also to reduce oxidative stress, thus effectively reversing neurite injury and neuronal apoptosis, so ALDH2 can be used as a potential target for prevention and treatment of neurodegenerative diseases.