Drugs Made of RNA: Development and Application of Engineered RNAs for Gene Therapy

Abstract

During the past decade, RNA has become a focus of investigation into new therapeutic schemes: antisense RNA, interfering RNA and trans-cleaving ribozymes are used to silence undesired gene expression. As an additional option with its own therapeutic potential, ribozymes may be employed to specifically alter the sequence of RNA. Among these RNA based strategies the mode of action varies: while antisense and interfering RNAs are capable of making specific contacts to other RNA molecules with the result of employing the cellular machinery for degradation of the RNA target, trans-cleaving ribozymes fold into specific three-dimensional structures to form catalytic centres and to specifically cleave a chosen RNA target. Beyond this, trans-splicing ribozymes have been engineered to first cleave a RNA target followed by ligation of a new RNA fragment delivered with the ribozyme. The latter strategy potentially extends the application of ribozymes from inhibition of gene expression to RNA repair, i. e. correction of genetic disorders at the level of RNA, and has already shown promising results in cell culture experiments. On the other side, advances in RNA synthesis, ribozyme engineering, delivery methods and expression systems have greatly enhanced the prospects of ribozymes, antisense and interfering RNAs in gene therapy. This review provides an overview of existing strategies for potential RNA based gene therapy. It is focussed on the engineering of ribozymes and functional RNAs to be used as drugs and on the basic molecular principles of their action.

Structure–function analysis of the ribozymes of chrysanthemum chlorotic mottle viroid: a loop–loop interaction motif conserved in most natural hammerheads

“…Hammerheads have potential therapeutic interest as catalytic antisense agents, because they can trans-hybridize to a complementary target substrate, cleave that substrate, and bind subsequently to a new target molecule (7). In this respect, a number of engineered hammerheads are currently under clinical trials (8,9). …”

Functional RNAs: combined assembly and packaging in VLPs

“…Functional RNAs such as small interfering RNAs, microRNAs (miRNAs) and short hairpin RNAs have therapeutic (1) and research applications (2,3). Here, we produce and assemble functional nanoparticles in which precursors of active RNAs are surrounded by a protective coat protein (CP).…”

Synthesis of Specifically Modified Oligonucleotides for Application in Structural and Functional Analysis of RNA

“…Synthetic RNAs are required for a large number of applications. Antisense oligonucleotides, ribozymes, aptamers, and siRNAs are required for medicinal diagnostic and therapy as well as for a wide variety of biochemistry and molecular biology studies [1, 2]. Furthermore, aptamers and reporter ribozymes are designed and applied in environmental diagnostics [3].…”