Suppression of c-jun influences nNOS expression in differentiated PC12 cells

In various animal models of central neuronal diseases, both c-jun and nNOS genes are expressed inside injured neurons; however, the mechanism of these two genes in neuronal diseases remains uncertain. Our previous studies have shown that c-jun expression always occurs prior to expression of nNOS in motoneuron injuries. We aimed to determine whether there is a correlation between c-jun and nNOS, and whether the crosstalk between these two genes regulated the pathological progression of injury-induced neuronal degeneration. In the present study, we used the neuron-like differentiated PC12 cells, which express c-jun and nNOS, to examine whether c-jun is the upstream molecule modulating nNOS expression. The c-jun small interfering RNAs (c-jun siRNA) were transfected into PC12 cells and cells were treated for 72 h in vitro. Western blotting and immunofluorescence were used to check the protein levels and the expression of c-jun and nNOS in differentiated PC12 cells. The results from the immunofluorescence experiments showed that the c-jun and nNOS proteins were co-expressed in the differentiated PC12 cells. The results from the western blotting experiments revealed that the protein levels of c-jun were significantly decreased by c-jun siRNA. Moreover, the nNOS protein levels were also downregulated in differentiated PC12 cells following c-jun siRNA treatment. The present study found that siRNA used against c-jun not only knocked down c-jun, but also downregulated the nNOS protein expression in differentiated PC12 cells. These results indicate that there is a functional relationship between c-jun and nNOS in differentiated PC12 cells.