Alpha-synuclein expression is up-regulated in NTera2 cells during neuronal differentiation but unaffected by exposure to cytokines and neurotrophic factors.

Increasing evidence has indicated that proinflammatory cytokines such as TNF-alpha and IL-1beta, produced by activated microglia and astrocytes, play a key role in progressive degeneration of the nigrostriatal dopaminergic neurons in Parkinson's disease (PD). Since alpha-synuclein is a major component of Lewy bodies in PD brains, we studied the constitutive and cytokine/neurotrophic factor-regulated expression of alpha-synuclein in cultured human neurons by Northern blot and Western blot analyses. The constitutive expression of alpha-synuclein mRNA was identified in a variety of human neural and non-neural cell lines. The levels of alpha-synuclein expression were elevated markedly in NTera2 teratocarcinoma cells following retinoic acid-induced neuronal differentiation, accompanied with an increased expression of synphilin-1, while they were unaltered in NTera2-derived differentiated neurons by exposure to TNF-alpha, IL-1beta, BDNF or GDNF. These results indicate that alpha-synuclein expression in human neurons is up-regulated during differentiation, but is unaffected by a panel of cytokines and neurotrophic factors which are supposed to be involved in the nigral neuronal death and survival.