In recent years, the world of genetic engineering has revolved around innovative tools capable of precise genome modifications. One of the most significant advancements in this arena is the CRISPR-associated transposons, or CASTs, which have emerged as vital elements for efficient genetic editing. Despite their potency, harnessing the full potential of CASTs for biomedical applications has proven to be a formidable challenge. Researchers at St. Jude Children’s Research Hospital are breaking new ground by introducing a high-throughput screening approach that effectively evaluates the efficiency and specificity of numerous CAST variants.
This pioneering research, conducted by a team led by co-first authors Seong Guk Park, PhD, and Elizabeth Kellogg, PhD, from the Department of Structural Biology at St. Jude, was recently published in the journal Nucleic Acids Research. Their method stands out as it enables the rapid optimization of promising CAST candidates, ultimately uncovering essential mechanistic insights that will inform further engineering endeavors. This advancement marks a significant stride in addressing the limitations that have traditionally encumbered the adaptation of CASTs for human applications.
CASTs, which were discovered in 2017, provide a one-step solution for genome editing by integrating large DNA sequences at designated locations in the genome, guided by RNA sequences. Their specificity has been well-documented within bacterial systems, their original hosts; however, they have been less effective in human cells. Consequently, the research team’s objective concentrated on enhancing these natural systems to increase their applicability in human and other eukaryotic organisms.
Corresponding author Elizabeth Kellogg emphasized the necessity of a scalable method to evaluate engineered CASTs’ strengths and weaknesses. Prior to the development of this high-throughput screening approach, the understanding of CASTs was limited to measuring overall activity, without thoroughly assessing the specificity of their DNA integrations. The researchers aimed to fill this void in knowledge by designing a method that could simultaneously measure both aspects.
Utilizing this new screening technique, the team focused on a specific subtype known as the V-K CAST. This variant is particularly advantageous due to its relatively simpler structure compared to other CASTs, making it ideal for experimentation. By altering the proteins of the V-K CAST, the researchers were able to explore a vast range of mutations, evaluating thousands of variants in a single experiment. This broad approach allowed them to delve deep into the mutational landscape of the CAST system, which was previously unexplored territory.
Co-first author Seong Guk Park elaborated on the motivation behind this study, revealing their intention to test all possible single mutations to identify those that could enhance CAST efficiency. Their comprehensive strategy, which did not target any specific regions of the CAST, was instrumental in uncovering beneficial mutations. The team’s exhaustive exploration yielded insights that could significantly impact future research in genetic editing.
Following the application of the V-K CAST mutational screening, the researchers discovered that certain combinations of the most promising mutations could have additive benefits. Specifically, they observed a fivefold increase in activity attributable to just a few modifications. Remarkably, this increase in activity did not come at the expense of specificity—an achievement that previous engineering strategies had been unable to accomplish. This kind of advancement exemplifies the potential of the team’s high-throughput screening method to revolutionize genetic engineering approaches.
With this pressing need for specificity and efficiency in genetic editing, Kellogg and her team are encouraged by the groundbreaking possibilities brought forth by this research. The intricate nature of the natural CAST systems presents hurdles, but the screening approach enables more aspirations in the design of proteins with enhanced capabilities. The researchers are optimistic about future developments resulting from this work, believing that it could lead to more minimal systems conducive for clinical applications.
The study not only underscores the steps taken by St. Jude’s researchers to optimize CASTs, but it also highlights the collaborative efforts undertaken by a diverse team of experts. The contributions of Jung-Un Park from the University of California, Berkeley, along with colleagues Esteban Dodero-Rojas, John Bryant Jr., and Geetha Sankaranarayanan, add depth to the findings and reflect the integrative nature of modern scientific research.
Funded by prominent organizations such as the National Institutes of Health, the Pew Charitable Trusts, and various other institutions, this study exemplifies a commitment to advancing genetic research. The financial backing underscores the importance of this research in providing innovative solutions to pressing health concerns, emphasizing the collaboration between research institutions and funding bodies in the pursuit of transformative scientific knowledge.
As research continues in this dynamic area, Kellogg and her colleagues will remain steadfast in their endeavors to refine CAST designs further. The high-throughput screen they’ve developed will facilitate ambitious efforts to progress in protein design. While the complexities inherent to natural systems are extensive, the newfound capabilities will undoubtedly catalyze advancements in genetic engineering, potentially revolutionizing therapies for genetic disorders and beyond.
The implications of this research stretch far beyond the laboratory. As these engineered CASTs find greater utility in clinical settings, they could pave the way for new therapeutic approaches, enabling precise modifications that enhance human health. With ongoing research and development, the future of genetic editing appears promising, with potential breakthroughs lying just ahead.
The journey of refining CRISPR-associated transposons is a testament to the synergy of scientific exploration and technological advancement. By tapping into the nuances of genetic editing, researchers are positioned to tackle some of humanity’s most enduring challenges, ultimately contributing to a healthier, more informed world.
In conclusion, this research not only leads to practical applications in genetic engineering but also exemplifies the broader potential of interdisciplinary cooperation in science. By embracing methodologies that enhance specificity and efficiency, researchers are forging new paths in the quest for medical breakthroughs, ensuring that the work at St. Jude Children’s Research Hospital resonates for generations.
Subject of Research: CRISPR-associated transposons (CASTs)
Article Title: Screening Approach Enhances CRISPR Genome-Editing Efficiency
News Publication Date: September 23, 2025
Web References: St. Jude Children’s Research Hospital, Nucleic Acids Research
References: National Institutes of Health, Pew Charitable Trusts, Cystic Fibrosis Foundation, Jane Coffin Childs Memorial Fund, Korea Health Industry Development Institute, National Cancer Institute, American Lebanese Syrian Associated Charities
Image Credits: St. Jude Children’s Research Hospital
Keywords
CRISPR, gene editing, genome engineering, CASTs, biomedical applications, specificity, efficiency, high-throughput screening, protein design, genetic disorders.
Tags: biomedical applications of CASTsCASTs for genetic engineeringchallenges in genetic editing applicationsCRISPR genome editing advancementsefficiency of genome editinghigh-throughput screening methodsmechanistic insights in genetic engineeringoptimization of CAST candidatesprecision genome modification techniquesRNA-guided DNA integration methodsSt. Jude Children’s Research Hospital researchstructural biology in CRISPR technology
