Therapeutic applications of group I intron‐based trans‐splicing ribozymes

Abstract

Since the breakthrough discovery of catalytic RNAs (ribozymes) in the early 1980s, valuable ribozyme-based gene therapies have been developed for incurable diseases ranging from genetic disorders to viral infections and cancers. Ribozymes can be engineered and used to downregulate or repair pathogenic genes via RNA cleavage mediated by trans-cleaving ribozymes or repair and reprograming mediated by trans-splicing ribozymes, respectively. Uniquely, trans-splicing ribozymes can edit target RNAs via simultaneous destruction and repair (and/or reprograming) to yield the desired therapeutic RNAs, thus selectively inducing therapeutic gene activity in cells expressing the target RNAs. In contrast to traditional gene therapy approaches, such as simple addition of therapeutic transgenes or inhibition of disease-causing genes, the selective repair and/or reprograming abilities of trans-splicing ribozymes in target RNA-expressing cells facilitates the maintenance of endogenous spatial and temporal gene regulation and reduction of disease-associated transcript expression. In molecular imaging technologies, trans-splicing ribozymes can be used to reprogram specific RNAs in living cells and organisms by the 3'-tagging of reporter RNAs. The past two decades have seen progressive improvements in trans-splicing ribozymes and the successful application of these elements in gene therapy and molecular imaging approaches for various pathogenic conditions, such as genetic, infectious, and malignant disease. This review provides an overview of the current status of trans-splicing ribozyme therapeutics, focusing on Tetrahymena group I intron-based ribozymes, and their future prospects. This article is categorized under: RNA in Disease and Development > RNA in Disease.

Non-Canonical Splicing and Its Implications in Brain Physiology and Cancer

“…Mechanisms of trans-splicing have been recently investigated as potential targets to obtain a functional correction of desired RNAs. Conveniently engineered trans-splicing molecules that contain the chosen splicing domains were delivered to cells, and by exploiting the nuclear splicing machinery (SMaRT, spliceosome-mediated RNA trans-splicing) or internal group I intron ribozymes, they were able to trans-splice the corrected coding sequences into target pre-mRNAs [ 215 , 216 , 217 ]. Both methods have been used to restore the wild-type functions of the tumour-suppressor proteins p16 and p53 in different models of solid tumours [ 218 , 219 , 220 , 221 ].…”

“…In the suicide gene therapy approach, inactive molecules are converted to active cytotoxic compounds in cancer cells via proteins encoded by exogenous trans-splicing sequences. To obtain specificity toward tumour cells, the trans-splicing reaction is targeted to genes that are overexpressed in cancer [ 215 ]. For example, a system using Herpes simplex virus thymidine kinase-ganciclovir has been trans-spliced into the transcript of hTERT [ 215 ].…”

“…To obtain specificity toward tumour cells, the trans-splicing reaction is targeted to genes that are overexpressed in cancer [ 215 ]. For example, a system using Herpes simplex virus thymidine kinase-ganciclovir has been trans-spliced into the transcript of hTERT [ 215 ]. Interestingly, additional selectivity can be introduced by adding tissue-specific promoters or responsive elements regulating the exogenous expression of the trans-splicing RNA molecules [ 227 , 228 , 229 , 230 , 231 , 232 ].…”

Mutation-Directed Therapeutics for Neurofibromatosis Type I

“…Moreover, trans-splicing group I intron ribozymes have been developed that reprogram hepatitis C virus and dengue virus RNA and induce apoptosis of infected cells, while other types of ribozymes have been proposed for addressing other infectious diseases, most notably HIV. We refer to Lee et al 64 for a recent review of therapeutic applications of trans-splicing group I intron ribozymes to inheritable genetic diseases, infectious diseases, and cancers.…”

At the Intersection of Biomaterials and Gene Therapy: Progress in Non-viral Delivery of Nucleic Acids

“…This has been achieved by incorporating miR target sites or hypoxia-inducible elements in ribozymes to regulate their activity in a miR expression status-dependent manner or the ambient cellular environment, respectively. The potential of trans -splicing ribozymes in gene therapy and as anti-viral and anti-cancer tools has been reviewed elsewhere (Lee et al, 2018).…”