Co-expression of multiple genes at a desired ratio is highly desirable for various basic research and biomedical applications including cell reprogramming1,2,3, expression of complex multisubunit protein-based therapeutic agents in gene therapy4,6,7,8, tagging of proteins for live-cell imaging or sorting9,10,11, and genome editing12,13,14,15,16. Several strategies for multigene co-expression have been developed, such as introducing multiple vectors, use of multiple promoters in a single vector, fusion proteins, proteolytic cleavage sites between genes and internal ribosome entry (IRE) sequences with 2A peptides. However, most of these approaches suffer from severe inefficiency or unbalanced expression.
The present article demonstrates the effectiveness of the t2a peptide as an efficient 2A-based multiple-gene expression system for enhanced biomedical applications. The t2a peptide, originally identified in foot-and-mouth disease virus belonging to the Picornaviridae family of viruses, enhances the expression of EGFP and RFP in PCKC cells inoculated with EtER sporozoites, as shown by enhanced nucleus localization of EGFP and secretion of RFP into parasitophorous vacuoles at trophozoite (24 h post-infection [hpi]) and 1st-generation schizont stages (48 and 72 hpi) phases.
Oligonucleotides encoding P2A, T2A, E2A and F2A were purchased from Bioneer and individually cloned into the SphI/BglII sites of pCS4+ plasmid (provided by Chang-Yeol Yeo). NLS-EGFP and membrane localization sequences mCherry were fused to the C-terminus of each of these 2A peptides, and the constructs were introduced into adenoviral packaging cells, amplified and then transduced to mouse livers. The resulting infectious adenoviruses were analyzed by WB and confocal microscopy.