Rationally designed DNA therapeutics can modulate human tyrosine hydroxylase expression by controlling specific G-quadruplex formation in its promoter

Abstract

Tyrosine hydroxylase (TH) catalyzes the rate-limiting step in catecholamine (CA) biosynthesis pathway making TH a molecular target for controlling CA production, specifically dopamine. Dysregulation of dopamine is correlated with neurological diseases such as Parkinson's disease (PD) and post-traumatic stress disorder (PTSD) among others. Previously, we showed that a 49-nucleotide guanine (G)-rich sequence within the human TH promoter adopts two different sets of G-quadruplex (GQ) structures (5ʹGQ and 3ʹGQ) where the 5ʹGQ uses G-stretches I, II, IV and VI in TH49 which enhances TH transcription, while the 3ʹGQ utilizes G-stretches II, IV, VI and VII which represses transcription. Herein, we demonstrated targeted switching of these GQs to their active state using rationally designed DNA GQ Clips (5ʹGQ and 3ʹGQ Clips) to modulate endogenous TH gene expression and dopamine production. As a translational approach, we synthesized a targeted nanoparticle delivery system to effectively deliver the 5ʹGQ Clip in vivo. We believe this strategy could potentially be an improved approach for controlling dopamine production in a multitude of neurological disorders including PD.