Applications of piggyBac Transposons for Genome Manipulation in Stem Cells

Table 2

Comparison of genome-wide screening libraries based on cDNA, RNAi, CRISPR/Cas9, and PB transposons.

	cDNA library	RNAi library	CRISPR/Cas9 library	piggyBac library
Work mode	Gain of function	Loss of function	Loss of function/gain of function	Loss of function/gain of function
Vehicle	cDNA	Sh/siRNA	sgRNA	piggyBac transposon plasmids
Targeting restrictions	Part of transcripts	Only targets mRNA	Protospacer adjacent motif (PAM) must be present	Only at TTAA site
Mutagenesis efficiency	≥2 standard deviations induced expression signals	≥70% gene knockdown	Knockout, knockdown, or overexpress with different kinds of libraries achievable	Activation levels of genes variable, inactivation achievable in haploidy
Genome coverage	Depend on library design	Depend on library design	Depend on library design	Genome-wide in principle, but influenced by integration site preference
Types of mutations	Overexpression	Knockdown	Chromosomal deletions and translocations	Gene activation and inactivation are due to transposon insertion
Reversibility	Potentially reversible	Potentially reversible	Knockdown or overexpressed libraries reversible, knockout libraries irreversible	Reversible
Limitations	Abundance of transcripts varies	High offtarget effects	Less offtarget effects	Biallelic gene inactivation rare in diploid cells; integrations for activation need to be upstream of the transcription start site
Cytotoxicity	Variable to high	Variable to high	Low	Low