The Basis and Promise of Programmable RNA Editing and Modification

Abstract

One key advantage of RNA over genomic editing is its temporary effects. Aside from current use of DNA-targeting CRISPR-Cas9, the more recently discovered CRISPR-Cas13 has been explored as a means of editing due to its RNA-targeting capabilities. Specifically, there has been a recent interest in identifying and functionally characterizing biochemical RNA modifications, which has spurred a new field of research known as “epitranscriptomics”. As one of the most frequently occurring transcriptome modifications, N6-methyladenosine (m6A) has generated much interest. The presence of m6A modifications is under the tight control of a series of regulators, and the ability of fusing these proteins or demethylases to catalytically inactive CRISPR proteins have resulted in a new wave of programmable RNA methylation tools. In addition, studies have been conducted to develop different CRISPR/Cas and base editor systems capable of more efficient editing, and some have explored the effects of in vivo editing for certain diseases. As well, the application of CRISPR and base editors for screening shows promise in revealing the phenotypic outcomes from m6A modification, many of which are linked to physiological, and pathological effects. Thus, the therapeutic potential of CRISPR/Cas and base editors for not only m6A related, but other RNA and DNA related disease has also garnered insight. In this review, we summarize/discuss the recent findings on RNA editing with CRISPR, base editors and non-CRISPR related tools and offer a perspective regarding future applications for basic and clinical research.

Gene targeting as a therapeutic avenue in diseases mediated by the complement alternative pathway

“…The two main approaches to target RNA are RNAi and ASO, although there are also emerging technologies that utilize CRISPR‐Cas13 or a “dead” Cas9 for RNA‐targeting approaches 1 . RNA‐targeting therapies are applied to inhibit the translation of disease‐associated genes transiently and selectively.…”

The epitranscriptome of high-grade gliomas: a promising therapeutic target with implications from the tumor microenvironment to endogenous retroviruses

“…Though several small molecule inhibitors of RNA modification regulators already exist, many must be redesigned to improve their BBB penetrance and levels in GBM. CRISPR-Cas systems developed for programmable RNA modification editing [ 101 ] and nucleotide-specific editing [ 102 ] expand the scope of RNA engineering and facilitate mechanistic understanding of the epitranscriptome. Like their DNA-targeting counterparts, RNA-targeting CRISPR-Cas systems may begin to be translated into the clinic in the coming years.…”

Novel epigenetic molecular therapies for imprinting disorders

“…dCas13-METTL3/14 as a N6-adenosine-methyltransferase (A to m 6 A), increases RNA stability and translation efficiency, leading to enhancement of gene expression [ 84 ]. CRISPR-Cas13d variants such as dCasRx is the smallest form targeting RNA, and is able to be packaged into lentivirus for improved delivery efficiency to primary cells [ 88 ]. As a m 6 A demethylase, dCasRx-ALKBH5 shows bidirectional modulation depending on targeting mRNA [ 89 ].…”