Ferulic Acid Induces NURR1 Expression and Promotes Dopaminergic Differentiation in Neural Precursor Cells

Abstract

Degeneration of dopaminergic (DA) neurons in the substantia nigra is known as the main cause of Parkinson's disease (PD). Preventing the loss of DA neurons alongside the cell-replacement therapy have brought tremendous hope for the treatment of PD. For this purpose, various studies have been done to find the specific DA neuro-protective compounds or progressing DA-differentiation methods. Ferulic acid (FA) has strong neuro-protective effects, but at this point its role on protection and differentiation of DA neurons is not well-defined. Mouse neural stem cells (mNSCs) were treated with FA and expressions of TH (tyrosine hydroxylase) and NURR1 as the DA neuron specific markers were determined using real time qRT-PCR and immunostaining assays . Finally, efficacy of FA on DA differentiation was evaluated in comparison with other methods using fibroblast growth factor 8b (FGF8b) and sonic hedgehog (SHH). Treatment with FA could increase the Th and Nurr1 gene expressions in mNSCs. Also, it enhanced β - tubullin - III expression and increased the neurite length in treated groups. Real time qRT-PCR and immunostaining assays showed that FA could increase DA differentiation in mNSCs effectively. Also, gene expression profile in some groups showed that FA can raise the differentiation rate of other neuronal subtypes such as cholinergic neurons. FA effectively induces the DA differentiation in neural precursor cells by its ability to increase the expression of the NURR1 transcription factor, which is a known transcription factor for differentiation of midbrain DA neurons.

Keywords: Dopaminergic; Ferulic acid; Nurr1; Tyrosine hydroxylase; differentiation; neural stem cell.

Fig 1

Effect of different concentrations of FA on expressions of Th, Nurr1 and β-tubulin 3 genes in mNSCs. As represented in schematic timeline, cells were treated for 7 days with 0, 50, 100, 200 and 300 µg/mL of FA (A-E). Real time qPCR results for Th, Nurr1 and β-Tub III gene expressions shows that FA 100 µg/mL had the most potent effect on expressions of Th and Nurr1 (F). Scale bars represent 50 µm (A-E). Data is presented as mean ± S.E.M

Fig. 2

Expression of Th, Chat and Gad1 genes in FA-terated group and its comparison with cells treated with DA induction factors (SHH and FGF8b) and control. NSCs were treated based on different groups: 1) no treatment or control, 2) FA 100 µg/mL, and 3) SHH+FGF8b (A-C), for seven days, and later the expressions of Th, Chat and Gad1 genes were evaluated (D). Scale bars are representing 50 µm (A-C). Data is presented as mean ± S.E.M

Fig. 3

Effect of FA on DA differentiation in comparison with conventional DA induction factors (SHH and FGF8b). To determine the DA differentiation in neurons, NSCs were treated with defined factors and then stained against TH, NURR1 and β-TUB III proteins (A-F). G & H are representing the percentage of TH- and NURR1-positive neurons respectively. Scale bars represent 25 µm (A) and 50 µm (B-F). Data is presented as mean ± S.E.M (***: P < 0.001 and ****: P < 0.0001)