BAC TG-EMBED: one-step method for high-level, copy-number-dependent, position-independent transgene expression

Area of Science:

• Molecular Biology
• Genetics
• Biotechnology

Background:

• Chromosome position effects and transgene silencing limit mini-gene expression in mammalian cells.
• Achieving high-level, reproducible transgene expression for therapeutic proteins or multiple transgenes is challenging.

Purpose of the Study:

• To develop a simple, one-step procedure for high-level, reproducible mini-gene expression in mammalian cells.
• To overcome position-dependent gene silencing and variability in transgene expression.

Main Methods:

• Mini-genes were inserted into a Bacterial Artificial Chromosome (BAC) containing the DHFR housekeeping gene locus.
• Multi-copy DHFR BAC insertions were integrated into mammalian chromosomes at various locations.
• Chromatin conformations of BAC insertions were analyzed.
• Reporter mini-gene expression stability was assessed during long-term culture with drug selection.

Main Results:

• Copy-number-dependent, position-independent mini-gene expression was achieved with BAC insertions.
• Multi-copy DHFR BAC insertions adopted similar large-scale chromatin conformations regardless of integration site.
• Stable expression of reporter mini-genes was maintained during continuous culture.
• The method was extended for reproducible, high-level expression of multiple mini-genes.

Conclusions:

• Embedding mini-genes within a BAC-specific chromatin structure prevents chromosome position effects.
• This BAC-based method enables robust and reproducible transgene expression in mammalian cells.
• The approach is suitable for both single and multiple transgene expression, with potential applications in gene therapy and biotechnology.