Targeted deubiquitination rescues distinct trafficking-deficient ion channelopathies

Area of Science:

• Biochemistry
• Molecular Biology
• Genetics

Background:

• Ion channel dysfunction, or channelopathies, arises from impaired protein stability and trafficking.
• Ubiquitination regulates ion channel surface expression but is challenging to target therapeutically due to its role in proteostasis.
• A unifying principle for treating diverse channelopathies may involve targeting protein stabilization pathways.

Purpose of the Study:

• To develop engineered deubiquitinases (enDUBs) for selective removal of ubiquitin from target ion channels.
• To investigate the efficacy of enDUBs in rescuing functional expression of mutant ion channels underlying long QT syndrome (LQT) and cystic fibrosis (CF).
• To explore enDUBs as a protein stabilization method and a tool for studying the ubiquitin code.

Main Methods:

• Development of engineered deubiquitinases (enDUBs) for targeted protein deubiquitination.
• Utilizing an LQT type 1 (LQT1) cardiomyocyte model to assess enDUBs' effect on ion channel function.
• Testing CF-specific enDUBs in combination with FDA-approved drugs (Orkambi, Trikafta) for cystic fibrosis mutations.

Main Results:

• enDUB treatment restored delayed rectifier potassium currents and normalized action potential duration in an LQT1 model.
• CF-targeted enDUBs synergistically enhanced the efficacy of existing CF pharmacotherapies for common and resistant mutations.
• The study demonstrated enDUBs' capability to rescue functional expression of disparate mutant ion channels.

Conclusions:

• Targeted deubiquitination using enDUBs is a potent strategy for protein stabilization and correcting diseases caused by ion channel trafficking defects.
• enDUBs offer a promising therapeutic avenue for diverse channelopathies, potentially serving as a unifying treatment approach.
• This technology provides a novel tool for in situ investigation of the ubiquitin code and its role in disease.