Protective Effects Of Aldh2 In β-amyloid-induced Neuronal Damage And Its Mechanism

As the world enters the process of accelerated aging society, Alzheimer’s disease a serious threat to the health of the elderly neurodegenerative disease incidence, mortality also showed an increasing trend, which is a heavy burden to the society and the family. However, clinically effective treatment of AD and its lack of efficacy is limited. The mainly reason is the lack of in-depth understanding of the pathogenesis of AD and explore the application of novel therapeutic agents for the treatment of AD’s target.Aβ is the major AD pathology- a main component of neuritic plaques in vivo by amyloid precursor protein production in the β- lyase acting. The current study suggests that neurons in the brain Aβ deposition may be a core pathogenic mechanism of AD, is also an important target for the treatment of AD.ALDH2, aldehyde dehydrogenase family is a member of the nuclear-encoded mitochondrial enzyme, evolutionary conserved, ubiquitously expressed in various organs of the body. Its main function is to acetaldehyde metabolism of alcohol dehydrogenation process can produce acetic acid, can reduce the risk of many alcohol-related diseases. Secondly, ALDH2 having the role of nitrate reductase, nitrates can be converted to biologically active nitric oxide, thereby red ucing the risk of sudden severe cardiovascular disease. Recent studies have found that, ALDH2 its direct and indirect conversion of the body’s tissues and organs, metabolic processes cytotoxic cells produce reactive aldehydes and other substances, has a significant protective effect of nerve cells, a variety of diseases and neurodegenerative related. Recent studies have found that, ALDH2 can be transformed in cytotoxic aldehydes body tissues and organs and cells in the metabolic process, a significant protective effect of nerve cells, and a variety of neurodegenerative diseases associated.Foreign epidemiological studies showed that, ALDH2 gene deletion were significantly higher in patients with Alzheimer’s disease; animal experiments showed that, ALDH2 gene knockout mice more susceptible to oxidative stress, showing age-related neurological degenerative pathology and memory loss and a series of neurological dysfunction.Cell experiments show that in primary cultured hippocampal neurons, overexpression of ALDH2 can effectively reduce the metabolite 4-HNE cause neuronal apoptosis, oxidative stress and mitochondrial damage.ALDH2 plays what role in neuronal apoptosis process caused by Aβ? Since ALDH2 mutation can increase the risk of suffering from AD using ALDH2 activator Alda-1 can plays neuronal protective effect caused by Aβ? Currently have no relevant reports.Objective: To confirm ALDH2 neuroprotective effects in AD pathological conditions, and further study of ALDH2 activation mechanism neuroprotective effect. Provide experimental evidence for the cause as a new target for the treatment of AD.Methods: Using HT22 mouse hippocampal neuronal cell line load 50?mol / L Aβ build AD cell model, following using ALDH2 specific activator Alda-1; ALDH2 inhibitor Daidzin. MTT assay cell viability; Flow cytometry, Tunel detect cell apoptosis. Western-bolt detected apoptosis-related proteins caspase3, Bcl2. Further in primary neural stem cells induced to differentiate AD cell model is further evidence ALDH2 neuronal protection. Neuronal mechanisms of the protective effect of ALDH2 activation, mitochondrial damage is one of the early features of Alzheimer’s disease, the use of transmission electron microscopy to detect cell mitochondria, superoxide anion fluorescent probes to detect ROS levels, Elisa detection 4-HN E levels of fluorescence Su enzymatic detection of intracellular ATP content.Result: We use the aggregation of Aβ treated HT22 cells, build AD cell damage model, MTT experiments showed significantly reduc for 24 hours. We then added Aβ processing ALDH2 activator Alda-1 50?mol/L, ALDH2 inhibitors Daidzin60?mol / L, MTT cell viability assay showed that adding Alda-1 50?mol / L significantly increased cell survival The use Daidzin60?mol / L inhibited cell viability decreased ALDH2 activity. Follow-up experiments are used above approach. We used flow cytometry to detect the effect on the rate of apoptosis after activation or inhibition of ALDH2, results showed that adding ALDH2 activator Alda-1 50?mol / L after the apoptosis rate and Aβ-treated group was significantly lower compared to after using ALDH2 inhibitors Daidzin no significant increase in the rate of apoptosis. Western-bolt detected apoptotic protein Caspase3 active, and the content of the anti-apoptotic protein Bcl2. Experimental results showed that after added ALDH2 activator of Alda-1 50?mol / L the intracellular Caspase3 active content decreased, Bcl2 were significantly increased. Finally, we use the Tunel staining of apoptotic cells ve rify the above phenomenon. Fluorescence microscopy when add Alda-1 green fluorescence- labeled apoptotic cel s was significantly reduced.To further demonstrate the neurons protective effects of ALDH2, using primary cultures of mouse neural stem cells were treated with 10% fetal bovine serum induced differentiation for five days, followed by drug intervention join Aβ25-35 50?mol / L, ALDH2 activator Alda-1 50?mol / L, ALDH2 inhibitors Daidzin60 ?mol / L. The results showed that after using Daidzin inhibit ALDH2 activity, differentiation of clone ball morphological abnormalities. The ALDH2 activation cloned ball more normal shape.TEM observation the mitochondria, compared with the normal control group, Aβ treatments presence of vacuoles and mitochondria membrane rupture, but after adding Alda-1 returned to normal mitochondrial morphology. ROS is one of the direct factors Aβ caused mitochondrial damage, we used a fluorescent probe DHE detected intracellular ROS level, found that after the addition ALDH2 activator Alda-1 ROS fluorescence intensity was significantly decreased. 4-HN E is under oxidizing conditions of cellular stress produce lipid peroxidation, mitochondrial DNA was binded to toxic aldehydes caused structural damage and mitochondrial dysfunction. ALDH2 can play its role in dehydrogenation reductase cells without damage to the formation of acetic acid. Experiments found that after ALDH2 activation can significantly reduce the intracellular content of 4-HN E. We used luciferase enzyme was detected intracellular ATP content, a significant increase in intracellular ATP content after ALDH2 activation.In summary ALDH2 activation can protect neurons against Aβ-induced damage, the possible mechanisms: ALDH2 can reduce mitochondrial toxicity of Aβ and reduce ROS, 4-HNE production, increase ATP content of mitochondria. Conclusion1. Alda-1 activation of ALDH2 can reduce Aβ- induced HT22 cells decreased survival, reduce Caspase3 expression, increased expressio n of Bcl2, suggesting that ALDH2 protection Aβ-induced neuronal damage.2. The neural stem cells differentiated cells in AD brain simulation environment, Aβ-induced neurons and astrocytes dysplasia, in the application of Alda-1 restored after, on the other hand confirmed that the neuroprotective ALDH2 effect.3. ALDH2 neuroprotective mechanism may reduce mitochondrial ROS damage and toxic aldehydes produced Aβ caused by increased ATP production.