The accumulation of a large amount of amyloid-β (Aβ42) in brain neurons is one of the debilitating characteristics of Alzheimer's disease. In this study, we determined the effects of peroxisome proliferator-activated receptor alpha (PPARα) activation on neuronal degeneration using a model of Aβ42-induced cytotoxicity. We found that 0.5 μM Aβ42 induced DNA damage and apoptosis in NT2N cells after 6 h of treatment. Co-treatment of Aβ42-treated cells with Wy14643, a PPARα ligand, significantly increased cell viability after 24 h compared with cells treated with Aβ42 alone. There were no differences in the protein levels of caspase-3, Bcl-2/Bax or p53 between cells treated with Aβ42 alone and those treated with both Aβ42 and Wy14643. However, the addition of Wy14643 significantly suppressed the Aβ42-induced upregulation of Endo G and AIF protein levels. Immunohistochemical analyses further demonstrated that Wy14643 reduced the expression of Endo G and AIF translocated from the cytoplasm into the nucleus, which occurred concomitantly with the decrease in DNA damage in Aβ42-treated cells. Our data clearly show that PPARα activation prevents DNA damage and neuronal cell apoptosis by decreasing the expression and translocation of AIF/Endo G to the nucleus in a caspase-3- and p53-independent pathway in the NT2N cell model. This role of PPARα in promoting neuron survival suggests a possible clinical application in treating Aβ42-associated neurotoxicity in Alzheimer's disease.

Activation of peroxisome proliferator-activated receptor alpha (PPARα) has been reported to modulate cell proliferation, migration, and differentiation in astrocytes. In this study, we used a retinoic acid (RA)-induced differentiation model of NTERA-2/clone D1 (NT2) cells to explore the functional significance of PPARα in neuronal differentiation. We found that activating PPARα by Wy14643 accelerated neuronal differentiation via regulating the expression of neuronal markers. RT-PCR assays showed a significant increase in NeuroD expression and a decrease in nestin expression in cells treated concomitantly with RA and Wy14643 for 2 days compared to the levels in cells treated with RA alone. Expression of MAP2 protein, a mature neuronal marker, was markedly upregulated at day 10 of Wy14643 treatment, which was maintained after 21 days of neuronal formation. Corresponding to the changes in MAP2 expression, the expression of Cdk5 was upregulated with Wy14643 exposure from day 10 to day 21. Moreover, cells treated with Wy14643 displayed higher expression levels of phospho-ERK and phospho-p38 in the differentiation process than cell treated with RA alone. These results indicated that activation of PPARα accelerated neuronal differentiation through upregulating the expression of NeuroD, MAP2, and Cdk5 and downregulating the expression of nestin. MAPK signals, ERK and p38, might contribute to the accelerated differentiation process. These findings suggest that PPARα plays a role in regulating neuronal differentiation and may be beneficial for functional recovery from neurological disorders.