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The effect of target site transcription on gene targeting in human cells in vitro
B Thyagarajan1, B L Johnson, C Campbell
1Department of Pharmacology, University of Minnesota Medical School, Minneapolis 55455, USA
Abstract:
We evaluate the effect of target site transcription on gene targeting in cultured human fibrosarcoma cells. A number of cell lines that harbored a plasmid recombination substrate within their chromosomal DNA were created. Gene targeting frequency was then measured at these different loci in the presence and absence of an agent that stimulated target site transcription. We observed that gene targeting was significantly enhanced by RNA transcription. The magnitude of transcription-stimulated gene targeting varied from 3-fold to > 20-fold. No increase in gene targeting was observed, however, when transcription proceeded away from, rather than through, the recombination site. Transcription-stimulated gene targeting was also observed when single-stranded plasmid vectors complementary to either the coding or template strand were used as recombination substrates. Our results indicate that gene targeting, like other forms of DNA recombination, can be stimulated by target site transcription. The implications of our observations on current models of transcription-stimulated recombination are discussed.
Insights
Target site transcription significantly enhances gene targeting in human cells. This RNA transcription effect, observed in gene editing, can increase targeting efficiency by over 20-fold.
Area of Science:
- Molecular Biology
- Genetics
- Cell Biology
Background:
- Gene targeting is a crucial tool in genetic research and therapeutic development.
- Understanding factors that influence gene targeting efficiency is essential for improving its application.
- The role of transcriptional activity at the target locus in gene targeting remains an area of investigation.
Purpose of the Study:
- To investigate the effect of target site transcription on gene targeting frequency in cultured human fibrosarcoma cells.
- To determine if RNA transcription influences the efficiency of gene targeting at specific chromosomal loci.
Main Methods:
- Creation of human fibrosarcoma cell lines containing a plasmid recombination substrate integrated into chromosomal DNA.
- Measurement of gene targeting frequency in the presence and absence of an agent that stimulates target site transcription.
- Analysis of gene targeting with transcription proceeding towards, away from, or through the recombination site, and with single-stranded plasmid vectors.
Main Results:
- Gene targeting was significantly enhanced by RNA transcription, with increases ranging from 3-fold to over 20-fold.
- Enhanced gene targeting was observed only when transcription proceeded through the recombination site, not away from it.
- Transcription-stimulated gene targeting was also demonstrated using single-stranded plasmid vectors complementary to either the coding or template strand.
Conclusions:
- Target site transcription acts as a stimulatory factor for gene targeting in human cells.
- These findings support the broader principle that DNA recombination processes can be modulated by transcriptional activity.
- The results have implications for understanding and optimizing gene targeting strategies in various biological contexts.