DNA methylation and de-methylation using hybrid site-targeting proteins

Table 2 Summary table of TALE and CRISPR based targeted demethylation tools

Strategy	Delivery	Efficacy	Duration	Locus	Peak site	Editing range	Target	Off-targets	Highlights	Refs
TALE-TET1CD, TALE-TET1	Transfection	~ 15%	4 days	KLF4 HBB	n.a.	n.a.	CpG	Off-targets from unspeci_c binding	First TALE-TE T study (2013)	[53]
dCas9-TET1CD	Transfection	~ 15%	24 h	BRCA1	n.a.	n.a.	CpG	Not detectable in LINE1 elements	First dCas9-TE T study (2016)	[56]
dCas9-TET1CD, MS2-TET1CD	Transfection	~ 15%	4 days	RANKL MMP2 MAGEB2	n.a.	~ 500 bp by multi-sgRNAs	CpG	Not detectable at sgRN A similar sites	MS2 coated sgRNA (2016)	[57]
dCas-TET1CD	Transduction	~ 26%	3 days	Dazl-Snrpn	n.a.	n.a.	CpG	Minimal o ff-target on methylation and expression using dCas9-ChIP-BS-seq and RNA-seq	Induce an active chromatin status for promote r. Sustainable in a human/mouse chimeric model (2016)	[40, 58]
dCas9-Sun Tag-TET1CD	Transfection	~ 80%	2 days	Gfap H19	n.a.	200–1000 bp	CpG	Not detectable (WGBS; RNA-seq)	Long range demethylation. In vivo delivery by in utero electroporation (2016)	[46]
Gal4-ROS1 CD	Transfection	n.a.	2 days	Reporter plasmid	n.a.	n.a.	CpG	n.a.	Direct removal of 5mC without hydroxymethylation (2017)	[59]

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