By transcription activator-like effector nucleases (TALENs) gene editing technology, the Chinese scientists have produced MECP2 gene mutation female cynomolgus monkey, which is the first non-human primate disease model constructed using TALENs technology(1).
Transcription activator-like effector nucleases (TALENs)(2-4) are genetic engineering recombinases generated by fusing a TAL effector DNA binding domain to a DNA cleavage domain. By combining such an engineered TALE with the wild-type FokI cleavage domain (which be responsible for cutting DNA double strands), people can create restriction enzymes that are specific for any desired DNA sequence. The technique successfully avoid inefficiency using RNAi for gene knockdown, while overcoming the zinc finger nuclease (ZFN)’s high cost disadvantage, and even more reduce the CRISPR/Cas9 serious off-target effects. TALEN technique makes targeted gene modification become more efficient and convenient.
In the past, scientists have only taken viral-mediated gene transfer to generate transgenic monkeys(5). In this study, the researchers via micro-injection method of MECP2 targeting TALEN plasmid into fertilized eggs of monkey, achieved the MECP2 gene effective editing, and they did not detect any off-target mutation. The researchers confirmed that MECP2 mutations were present among the monkey’s skin, umbilical cord and placenta. Now, the monkey has been a few months old.
The mutation of methyl-CpG-binding protein 2 (MECP2) is proved to associate with neurodevelopmental disorder in the grey matter leading cerebroatrophic hyperammonemia in human(6).
1.H. Liu et al., TALEN-Mediated Gene Mutagenesis in Rhesus and Cynomolgus Monkeys. Cell stem cell 14, 323 (Mar 6, 2014).
2.J. Boch, TALEs of genome targeting. Nature biotechnology 29, 135 (Feb, 2011).
3.J. Boch et al., Breaking the code of DNA binding specificity of TAL-type III effectors. Science 326, 1509 (Dec 11, 2009).
4.M. Christian et al., Targeting DNA double-strand breaks with TAL effector nucleases. Genetics 186, 757 (Oct, 2010).
5.S. H. Yang et al., Towards a transgenic model of Huntington’s disease in a non-human primate. Nature 453, 921 (Jun 12, 2008).
6.R. E. Amir et al., Rett syndrome is caused by mutations in X-linked MECP2, encoding methyl-CpG-binding protein 2. Nature genetics 23, 185 (Oct, 1999).