Increasing Specificity of Targeted DNA Methylation Editing by Non-Enzymatic CRISPR/dCas9-Based Steric Hindrance

Abstract

As advances in genome engineering inch the technology towards wider clinical use—slowed by technical and ethical hurdles—a newer offshoot, termed “epigenome engineering”, offers the ability to correct disease-causing changes in the DNA without changing its sequence and, thus, without some of the unfavorable correlates of doing so. In this review, we note some of the shortcomings of epigenetic editing technology—specifically the risks involved in the introduction of epigenetic enzymes—and highlight an alternative epigenetic editing strategy using physical occlusion to modify epigenetic marks at target sites without a requirement for any epigenetic enzyme. This may prove to be a safer alternative for more specific epigenetic editing.

The role of epigenetic mechanisms in the long‐term effects of early‐life adversity and mother–infant relationship on physiology and behavior of offspring in laboratory rats and mice

“…Third, to be efficient, methylation requires prolonged high expression of dCas9-DNMT3A that declines rapidly after the termination of dCas9-DNMT3A expression (Sapozhnikov & Szyf, 2023). Four, DNMTs exhibit a nonspecific activity, independent of targeting, that makes them unsuitable for precise epigenetic editing (Sapozhnikov & Szyf, 2023). Five, this technique is selective to the gene but not the position of acetylated histones.…”

“…Second, it can involve off-target effects-unintended modifications that occur at genomic loci other than the intended target site (Zhang et al, 2015). Third, to be efficient, methylation requires prolonged high expression of dCas9-DNMT3A that declines rapidly after the termination of dCas9-DNMT3A expression (Sapozhnikov & Szyf, 2023). Four, DNMTs exhibit a nonspecific activity, independent of targeting, that makes them unsuitable for precise epigenetic editing (Sapozhnikov & Szyf, 2023).…”