Physiological and pathophysiological characteristics of ataxin-3 isoforms

Area of Science:

• Neuroscience
• Genetics
• Biochemistry

Background:

• Ataxin-3 is a deubiquitinating enzyme implicated in Machado-Joseph disease (MJD).
• The ATXN3 gene exhibits alternative splicing and polymorphisms, leading to diverse protein isoforms.
• One common polymorphism introduces a premature stop codon in an ataxin-3 isoform.

Purpose of the Study:

• To investigate the impact of ATXN3 isoforms and a premature stop codon on ataxin-3 function.
• To elucidate the role of these variations in MJD pathogenesis.
• To explore interactions between normal and disease-associated ATXN3 alleles.

Main Methods:

• Analysis of ataxin-3 isoform stability, deubiquitination activity, subcellular localization, and protein interactions.
• Assessment of aggregation properties of different ataxin-3 isoforms.
• Investigation of functional interactions between normal and polyglutamine-expanded ATXN3 allelic variants.

Main Results:

• Alternative splicing and the premature stop codon alter ataxin-3 stability, enzymatic activity, and cellular distribution.
• Polyglutamine repeat expansion stabilizes ataxin-3, with isoforms exhibiting differential aggregation.
• Interactions between ATXN3 allelic variants modulate both physiological and pathological properties of ataxin-3.

Conclusions:

• ATXN3 isoforms and their interactions significantly affect ataxin-3 function and MJD pathogenesis.
• Protein isoforms and allelic interactions serve as crucial disease modifiers in MJD.
• These findings underscore the importance of considering protein isoforms and allelic interplay in inherited neurodegenerative diseases.