Huntingtin Exists as Multiple Splice Forms in Human Brain.

Area of Science:

• Genomics and Molecular Biology
• Neuroscience
• Transcriptomics

Background:

• Huntington's disease (HD) is caused by a CAG repeat expansion in the huntingtin (HTT) gene.
• While the major HTT transcripts are known, alternative splicing and novel transcripts remain underexplored.
• Alternative splicing diversifies the transcriptome and proteome, suggesting potential for uncharacterized HTT variants.

Purpose of the Study:

• To investigate the existence of alternative transcripts for the human huntingtin (HTT) gene.
• To identify and characterize novel splice variants of HTT.
• To assess the functional significance of identified HTT splice variants using protein modeling.

Main Methods:

• Employed an overlapping RT-PCR approach to detect novel HTT splice variants.
• Analyzed human brain samples from both Huntington's disease patients and healthy controls.
• Utilized 3D protein homology modeling to predict the functional impact of novel HTT isoforms.

Main Results:

• Identified multiple previously unreported novel HTT transcripts.
• Discovered 22 splice variants, with eight in-frame variants potentially encoding new HTT protein isoforms.
• Characterized two variants, HTT Δex4,5,6 (exon skipping) and HTTex41b (novel exon inclusion), showing potential functional impact on nuclear localization and post-translational modification sites.

Conclusions:

• The discovery of novel HTT transcripts has significant implications for understanding HTT protein expression and function.
• Alternative splicing of HTT plays a critical role in disease mechanisms.
• Understanding HTT alternative splicing is vital for developing targeted therapeutics for Huntington's disease, such as RNA silencing or splicing correction.