piggybac

piggyBac is a family of DNA transposons originally isolated from the cabbage looper moth Trichoplusia ni. The name piggyBac was developed to describe the transposable element encoding a transposase (PBase) that enables cut-and-paste transposition. It has become one of the most widely used transposon systems for genetic engineering in eukaryotes.

Mechanism: The piggyBac transposase recognizes terminal inverted repeats flanking the transposon and catalyzes excision and insertion. It transposes specifically into TTAA tetranucleotide target sites in the host genome and excises cleanly, restoring the TTAA site without a residual footprint.

System design: A typical piggyBac system involves a donor transposon plasmid carrying the gene of interest flanked by piggyBac terminal repeats and a source of transposase. Delivery into cells allows integration of the cargo into the genome. Transposase can be provided transiently, increasing safety and enabling removal if desired. Hyperactive variants such as hyPBase have been developed to improve transposition efficiency in mammalian cells.

Applications and advantages: Due to its large cargo capacity, broad host range, and efficient transposition, piggyBac is widely used to generate stable transgenic cell lines and organisms, model gene function, and deliver reprogramming factors for induced pluripotent stem cell generation. It is favored for non-viral delivery and relatively stable genomic integration compared with some other methods.

Limitations and considerations: Integration occurs at TTAA sites, causing potential insertional mutagenesis and biased genomic distribution. Although excision can be footprint-free, sustained expression of transposase can risk remobilization; thus, transient expression or removal strategies are employed. Ethical and safety considerations apply to animal and human research, and use is typically regulated by institutional guidelines.