Huntingtin Ubiquitination Mechanisms and Novel Possible Therapies to Decrease the Toxic Effects of Mutated Huntingtin

Area of Science:

• Neurodegenerative Disorders
• Molecular Biology
• Drug Discovery

Background:

• Huntington Disease (HD) is a lethal neurodegenerative disorder caused by expanded CAG repeats in the HTT gene.
• Mutated huntingtin protein (mHtt) forms aggregates, leading to neuronal ER stress, injury, and apoptosis.
• Degrading mHtt via the ubiquitin-proteasome system (UPS) is a promising therapeutic strategy.

Purpose of the Study:

• To elucidate the mechanism of mHtt degradation by the UPS.
• To explore the role of E3 ligase proteins in mHtt degradation.
• To discuss the potential of PROteolysis TArgeting Chimeras (PROTACs) for HD therapy.

Main Methods:

• Focus on the ubiquitin-proteasome system (UPS) pathway for mHtt degradation.
• Detailed analysis of E3 ligase structure-function relationships.
• Conceptual framework for PROTAC application in Huntington's Disease.

Main Results:

• The UPS plays a significant role in mHtt degradation, surpassing the autophagy-lysosomal pathway.
• E3 ligases are key regulators of mHtt ubiquitination and degradation.
• PROTACs can induce proximity between mHtt and E3 ligases, promoting mHtt ubiquitination.

Conclusions:

• Targeting mHtt degradation via the UPS is a viable therapeutic approach for HD.
• PROTACs represent a novel therapeutic modality for Huntington's Disease by facilitating mHtt clearance.
• Further research into E3 ligase-specific PROTACs could lead to effective HD treatments.