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Front. Neurosci. | doi: 10.3389/fnins.2018.00075

Precise excision of the CAG tract from the huntingtin gene by Cas9 nickases

Magdalena Dabrowska1, Wojciech Juzwa2,  Wlodzimierz J. Krzyzosiak1 and  Marta Olejniczak1*
  • 1Department of Molecular Biomedicine, Institute of Bioorganic Chemistry (PAS), Poland
  • 2Department of Biotechnology and Food Microbiology,, Poznan University of Life Sciences, Poland

Huntington’s disease (HD) is a progressive autosomal dominant neurodegenerative disorder caused by the expansion of CAG repeats in the first exon of the huntingtin gene (HTT). The accumulation of polyglutamine-rich huntingtin proteins affects various cellular functions and causes selective degeneration of neurons in the striatum. Therapeutic strategies used to date to silence the expression of mutant HTT include antisense oligonucleotides, RNA interference-based approaches and, recently, genome editing with the CRISPR/Cas9 system. Here, we demonstrate that the CAG repeat tract can be precisely excised from the HTT gene with the use of the paired Cas9 nickase strategy. As a model, we used HD patient-derived fibroblasts with varied numbers of CAG repeats. The repeat excision inactivated the HTT gene and abrogated huntingtin synthesis in a CAG repeat length-independent manner. Because Cas9 nickases are known to be safe and specific, our approach provides an attractive treatment tool for HD that can be extended to other polyQ disorders.

Keywords: Genome editing, CRISPR/Cas9, Neurodegenerative Diseases, Repeat expansion, Engineered nucleases, CAG repeats, paired nickases

Received: 28 Nov 2017; Accepted: 29 Jan 2018.

Edited by:

Sandro Alves, Brainvectis Therapeutics, France

Reviewed by:

Panchanan Maiti, University of California, Los Angeles, United States
Nicole Déglon, Centre Hospitalier Universitaire Vaudois (CHUV), Switzerland  

Copyright: © 2018 Dabrowska, Juzwa, Krzyzosiak and Olejniczak. This is an open-access article distributed under the terms of the Creative Commons Attribution License (CC BY). The use, distribution or reproduction in other forums is permitted, provided the original author(s) and the copyright owner are credited and that the original publication in this journal is cited, in accordance with accepted academic practice. No use, distribution or reproduction is permitted which does not comply with these terms.

* Correspondence: Dr. Marta Olejniczak, Institute of Bioorganic Chemistry (PAS), Department of Molecular Biomedicine, Noskowskiego 12/14, Poznań, 61-704, Poland, marta.olejniczak@ibch.poznan.pl