Cytosine extensions optimize case activity for telomere length regulation: implications for CRISPR-based therapies–A short communication
Open accessAbstract
Telomeres are nucleoprotein structures that play a crucial role in maintaining genomic stability, and their length determines cellular lifespan. Telomere shortening is linked to cellular senescence and an increased risk of cancer. The CRISPR-Cas9 system has emerged as a tool for genome engineering and telomere length regulation. However, several factors, including chromatin accessibility, the efficiency of Double-Stranded Break (DSB) repair and the specificity of the sgRNA/Cas9 complex, limit the efficiency of Cas9-mediated telomere length regulation. Recent studies have demonstrated the use of modified Cas9 nucleases, such as Cas9-NG, and the development of modified sgRNAs to improve the efficiency of Cas9-mediated telomere length regulation. In this study, Bhattacharyya, et al. investigated the optimization of Cas9 activity through the addition of cytosine (C) extensions to the 5’ end of sgRNAs. They found that C extensions significantly increased Cas9 activity at telomeres and demonstrated that the optimal length of C extensions was three Cs. The addition of C extensions did not affect the specificity of the sgRNA/Cas9 complex, as assessed by the frequency of off-target DSBs. These findings have important implications for the development of CRISPR-Cas9-based therapies for telomere-related diseases. Further studies are needed to confirm these findings and optimize the use of C extensions in different cell types and disease contexts.
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Truncating the gRNA can decrease editing efficiency.
“Truncating the gRNA from 20 nucleotides to 17–18 nucleotides has been shown to reduce off-target activity (Fu et al., 2014), though it can also decrease editing efficiency (Sai, 2021).”
From Emerging applications of gene editing technologies for the development of climate-resilient crops (2025) · cites this paper as Sai, 2021
The Optimization of Cas9 section reports that adding cytosine extensions to sgRNAs increased Cas9 activity at telomeres. Neither that section nor the passages returned for searches on truncated and shorter guide RNAs addresses whether shortening a gRNA decreases editing efficiency. Page numbers were not available in our copy. (LLM, conf=0.75)
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Armanios, M., & Blackburn, E. H. (2012) · Nature Reviews Genetics · doi:10.1038/nrg3246 · Cited by 982 · see citing works
Telomeres and telomerase: Their mechanisms of action and the effects of altering their functions
Blackburn, E. H. (2005) · FEBS Letters · doi:10.1016/j.febslet.2004.11.036 · Cited by 838 · see citing works
Removal of Shelterin Reveals the Telomere End-Protection Problem
Sfeir, A. J., & de Lange, T. (2012) · Science · doi:10.1126/science.1218498 · Cited by 578 · see citing works
Leung, N., Turbide, C., Olson, M., Marcus, V., Jothy, S., & Beauchemin, N. (2006) · Oncogene · doi:10.1038/sj.onc.1209541 · Cited by 95 · see citing works
The role of RNA N6-methyladenosine methyltransferase in cancers
Huang, J., Chen, Z., Chen, X., Chen, J., Cheng, Z., & Wang, Z. (2020) · Molecular Therapy — Nucleic Acids · doi:10.1016/j.omtn.2020.12.021 · Cited by 31 · see citing works
How to Use the H1 Deep Transcranial Magnetic Stimulation Coil for Conditions Other than Depression
Tendler, A., Roth, Y., Barnea‐Ygael, N., & Zangen, A. (2017) · Journal of Visualized Experiments · doi:10.3791/55100 · Cited by 18 · see citing works
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- Alder JK, Guo N, Kembou F, Parry EM, Anderson CJ, Gorgy E, Walsh MF, Sussan T, Biswal S, Mason K. Telomere length is a determinant of emphysema susceptibility. American Journal of Respiratory and Critical Care Medicine. 2015; 192(4): 479-486. https://doi.org/10.1164/rccm.201412-2140OC · DOI
- O'Connor MS, Safari A, Liu J, Qin L. The effects of Cas9-targeting-induced mutations on the mouse gut microbiome. Genome biology. 2018; 19(1): 1-16. https://doi.org/10.1186/s13059-018-1474-0 · DOI
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Emerging applications of gene editing technologies for the development of climate-resilient crops
Chavhan, R. L., Jaybhaye, S. G., Hinge, V. R., Deshmukh, A. S., Shaikh, U. S., Jadhav, P. K., Kadam, U. S., & Hong, J. C. (2025) · Frontiers in Genome Editing · doi:10.3389/fgeed.2025.1524767 · Cited by 43 · see citing works
“Truncating the gRNA from 20 nucleotides to 17 – 18 nucleotides has been shown to reduce off-target activity (Fu et al., 2014), though it can also decrease editing ef fi ciency (Sai, 2021).”
- Authors
- YRKM, S.
- Affiliations
- GITAM University (IN)
- Corresponding author
- YRKM, Sai
- ORCID
- YRKM, Sai
- Venue
- Annals of Molecular and Genetic Medicine
- Published
- 2021-12-28
- Volume
- 5
- Issue
- 1
- Pages
- 001-003
- ISSN
- 2692-4595 (ISSN-L)
- OpenAlex
- W4376484073
- Cited by
- 1
- References
- 6
- Citations by year
- 2025: 1
- FWCI
- 0.00
- Type
- journal article
- Language
- en
- Update notices
- new_edition (2021-12-28)
- Open access
- diamond
- doi.org
- Locations
- Annals of Molecular and Genetic Medicine (publishedVersion)
- Topics
- Life Sciences › Biochemistry, Genetics and Molecular Biology › Molecular Biology › CRISPR and Genetic Engineering
- Health Sciences › Medicine › Physiology › Telomeres, Telomerase, and Senescence
- Life Sciences › Biochemistry, Genetics and Molecular Biology › Molecular Biology › DNA and Nucleic Acid Chemistry
- Keywords
- telomere length regulation, CRISPR/Cas9, telomere shortening, genome editing
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