High-frequency intrachromosomal gene conversion induced by triplex-forming oligonucleotides microinjected into mouse...

Area of Science:

• Molecular Biology
• Genetics
• Biotechnology

Background:

• Site-specific recombination is crucial for genetic engineering and understanding DNA repair mechanisms.
• Triple helix-forming oligonucleotides (TFOs) are designed to bind specific DNA sequences, offering potential for targeted genetic manipulation.
• Previous methods for inducing recombination often lack specificity or efficiency in mammalian chromosomal sites.

Purpose of the Study:

• To evaluate the efficacy of TFOs in promoting recombination at specific chromosomal locations in mammalian cells.
• To investigate the potential of TFOs as tools for targeted gene modification.

Main Methods:

• A mouse LTK(-) cell line was engineered with two mutant copies of the herpes simplex virus thymidine kinase (TK) gene as direct repeats.
• Microinjection or cationic lipid transfection was used to deliver TFOs designed to bind a polypurine site between the TK gene repeats.
• Genomic Southern blotting was employed to analyze the recombination events and gene conversion in resulting clones.

Main Results:

• Microinjected TFOs induced recombination at frequencies up to 1%, a 2,500-fold increase over spontaneous background levels.
• Both psoralen-conjugated and unconjugated TFOs demonstrated efficient, sequence-specific induction of recombination.
• TFO-mediated recombination resulted in gene conversion events, with either the upstream or downstream TK gene corrected to wild-type.

Conclusions:

• TFOs are potent tools for inducing site-specific recombination within chromosomal loci in mammalian cells.
• Efficient intracellular delivery methods enhance TFO effectiveness for targeted genetic modification.
• TFOs hold promise for advancing gene therapy and genome engineering applications.