α-Synuclein overexpression represses 14-3-3θ transcription.

Previous gene microarray studies have shown that expression of 14-3-3θ is significantly decreased in an α-synuclein transgenic mouse model. In this study, we tested whether α-synuclein can regulate 14-3-3θ transcription. We demonstrate that the 14-3-3θ mRNA level is decreased in SH-SY5Y cells overexpressing α-synuclein. Luciferase activity under the control of the 14-3-3θ promoter is reduced both in stable SH-SY5Y cells constitutively overexpressing α-synuclein and in doxycycline-inducible SH-SY5Y cells upon α-synuclein induction, suggesting that the regulation of 14-3-3θ by α-synuclein occurs at the transcriptional level. Knockdown of α-synuclein by RNA interference does not increase the 14-3-3θ mRNA level. These findings suggest that α-synuclein represses 14-3-3θ transcription under pathologic conditions, but that regulation of 14-3-3θ expression is not a function of endogenous α-synuclein at baseline.