A human CAGinSTEM platform for decoding HTT repeats’ somatic instability links CAG interruption to HD pathology in neurons
Somatic CAG instability in the mutant Huntingtin (HTT) gene is increasingly recognized as a key hallmark of Huntington's disease (HD). Using our novel human CAGinSTEM platform, we manipulated cis genetic elements influencing instability in human HD neurons, monitoring repeat length. Quality-controlled CRISPR-engineered stem cells with increasing CAG lengths and clinical haplotypes were analyzed using third-generation sequencing. Our findings link interruptions in the CAG repeat, especially the loss or duplication of the penultimate CAA of canonical alleles, to significant instability modulation. Notably, four internal CAA interruptions completely abolish CAG instability, reversing HD phenotypes such as altered striatal fate acquisition and nuclear disorganization. This platform highlights the role of cis modifiers, emphasizing the direct influence of HTT DNA repeat composition on CAG instability and providing a robust framework for modeling HTT repeat instability in vitro.
Authors
- Vincenza Colonna (ORCID: https://orcid.org/0000-0002-3966-0474)
- Maria Lidia Mignogna (ORCID: https://orcid.org/0000-0001-9144-6363)
- Raffaele Iennaco (ORCID: https://orcid.org/0000-0002-7309-7232)
- Simone Maestri (ORCID: https://orcid.org/0000-0002-1192-0684)
- Giulio Formenti (ORCID: https://orcid.org/0000-0002-7554-5991)
- Chiara Zuccato (ORCID: https://orcid.org/0000-0003-1771-3392)
- Dario Besusso (ORCID: https://orcid.org/0000-0001-9793-9644)
- Andrea Cossu (ORCID: https://orcid.org/0000-0003-4086-8640)
- Laura Antonelli (ORCID: https://orcid.org/0000-0002-4031-099X)
- Elena Cattaneo (ORCID: https://orcid.org/0000-0002-0755-4917)
- Paola Conforti (ORCID: https://orcid.org/0000-0002-0829-1397)
- Francesco Gregoretti (ORCID: https://orcid.org/0000-0003-3822-1215)
- Ilaria Campus
- Mariacristina Crosti (ORCID: https://orcid.org/0000-0001-8314-1391)
- Gianluca Damaggio (ORCID: https://orcid.org/0000-0001-6567-0660)
- Saveria Mazzara (ORCID: https://orcid.org/0000-0003-1799-2360)
- Riccardo L. Rossi (ORCID: https://orcid.org/0000-0002-4964-3264)
- Andrea Scolz (ORCID: https://orcid.org/0009-0005-6227-7608)
- Gennaro Oliva (ORCID: https://orcid.org/0000-0001-5676-2133)
- Camilla Trovesi
- Matteo Cereda (ORCID: https://orcid.org/0009-0008-5134-6390)
- Francesco Cortina
- Davide Scalzo
- Martina Zobel
Institutions
- Institute for High Performance Computing and Networking (IT)
- Institute of Genetics and Biophysics (IT)
- Istituto Nazionale Genetica Molecolare (IT)
Publication Details
- Journal
- Cell Reports
- Published
- 2025-12-01
- DOI
- https://doi.org/10.1016/j.celrep.2025.116685
- Citations
- 1
- Primary Topic
- Genetic Neurodegenerative Diseases
- Type
- article
- Field-Weighted Citation Impact
- 0.91