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Author Notes:

Correspondence and requests for materials should be addressed to G.B. (email: gang.bao@rice.edu)

Author contributions: E.J.F. conceived of the concept, performed experiments, and wrote the manuscript with the help of all authors.

C.M.A., D.E.W., M.T.B., and H.D. performed experiments.

G.B. and M.L.K. directed the research.

Competing financial interests: E.J.F. and G.B. have filed a provisional patent application on the basis of these results.



  • Science & Technology
  • Multidisciplinary Sciences
  • Science & Technology - Other Topics
  • RNA
  • TALE
  • TOOL
  • DNA
  • Genetic Engineering
  • Protein delivery

Trans-spliced Cas9 allows cleavage of HBB and CCR5 genes in human cells using compact expression cassettes


Journal Title:

Scientific Reports


Volume 5


, Pages 10777-10777

Type of Work:

Article | Final Publisher PDF


CRISPR/Cas9 systems have been used in a wide variety of biological studies; however , the large size of CRISPR/Cas9 presents challenges in packaging it within adeno-associated viruses (AAVs) for clinical applications. We identified a two-cassette system expressing pieces of the S. pyogenes Cas9 (SpCas9) protein which splice together in cellula to form a functional protein capable of site-specific DNA cleavage. With specific CRISPR guide strands , we demonstrated the efficacy of this system in cleaving the HBB and CCR5 genes in human HEK-293T cells as a single Cas9 and as a pair of Cas9 nickases. The trans-spliced SpCas9 (tsSpCas9) displayed ∼35% of the nuclease activity compared with the wild-type SpCas9 (wtSpCas9) at standard transfection doses , but had substantially decreased activity at lower dosing levels. The greatly reduced open reading frame length of the tsSpCas9 relative to wtSpCas9 potentially allows for more complex and longer genetic elements to be packaged into an AAV vector including tissue-specific promoters , multiplexed guide RNA expression , and effector domain fusions to SpCas9. For unknown reasons , the tsSpCas9 system did not work in all cell types tested. The use of protein trans-splicing may help facilitate exciting new avenues of research and therapeutic applications through AAV-based delivery of CRISPR/Cas9 systems.

Copyright information:

© 2015, Macmillan Publishers Limited

This is an Open Access work distributed under the terms of the Creative Commons Attribution 4.0 International License (https://creativecommons.org/licenses/by/4.0/).
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