Background

Stuttering, also known as childhood-onset fluency disorder, is a chronic neurodevelopmental disorder that affects 1% of the population and can greatly impact an individual's social, occupational, and academic functioning. Prior research has shown dopamine D2 antagonists are effective in reducing the severity of stuttering symptoms, but these compounds can be associated with metabolic and movement disorder adverse effects. Ecopipam is an investigational medication that acts as a selective dopamine D1 receptor antagonist. This mechanism should reduce the likelihood of metabolic and movement disorder adverse effects of D2 antagonists.

Method

This open-label pilot study investigated ecopipam in the treatment of adults who stutter.

Results

The results showed that a majority of participants demonstrated improvement in their stuttering. The medication was well tolerated.

Conclusions

These positive, preliminary findings suggest that a doubleblind, randomized controlled clinical trial to examine the efficacy of ecopipam in the treatment of stuttering is warranted.

Proteasomes are multi-subunit protease complexes found in all domains of life. The maturation of the core particle (CP), which harbors the active sites, involves dimerization of two half CPs (HPs) and an autocatalytic cleavage that removes β propeptides. How these steps are regulated remains poorly understood. Here, we used the Rhodococcus erythropolis CP to dissect this process in vitro. Our data show that propeptides regulate the dimerization of HPs through flexible loops we identified. Furthermore, N-terminal truncations of the propeptides accelerated HP dimerization and decelerated CP auto-activation. We identified cooperativity in autocatalysis and found that the propeptide can be partially cleaved by adjacent active sites, potentially aiding an otherwise strictly autocatalytic mechanism. We propose that cross-processing during bacterial CP maturation is the underlying mechanism leading to the observed cooperativity of activation. Our work suggests that the bacterial β propeptide plays an unexpected and complex role in regulating dimerization and autocatalytic activation.