SMaRT™ RNA Platform – General background information
VIRxSYS’ RNA platform technology, Spliceosome-Mediated RNA Trans-splicing (“SMaRT™” or “SMaRT™ RNA”), is a novel, fully-patented, highly published, and versatile RNA technology, which has been successfully tested in various small animal models for multiple disease indications.
This proprietary technology can be viewed as a second generation of RNA technology, capable of repairing and re-programming genes at the RNA level. SMaRT™ accomplishes this by targeting gene transcripts in a cell. A gene transcript is the RNA copy of the gene itself, which is then translated into a protein. Contrary to all other existing technologies, SMaRTTM can efficiently delete any defective or otherwise unwanted part of a gene transcript, and insert, or “splice-in,” new genetic information leading to a healthy, functional protein. SMaRT™ is analogous to a genomic word processor which can delete and add letters, correcting a misspelled word or creating an entirely new word, which is desired for a situation.
SMaRT™ technology has a much broader array of possible therapeutic and diagnostic applications than RNA interference (RNAi) and microRNA (miRNA) can offer. Most of the RNA technologies currently being advanced deploy RNA modifications as “gene silencers” to block selected gene functions. However SMaRT™ can be used to repair genes which are defective, or to completely reprogram a specific gene transcript to produce a totally different protein of therapeutic interest, such as diverting plasma albumin production in the liver toward apolipoprotein A-I (apoA-I), factor VIII, or even small antibody fragments.
VIRxSYS' SMaRT™ technology has been demonstrated in many in vivo proof of principle animal studies for multiple diseases. It is currently the foundational technology for VIRxSYS’ preclinical therapies for cardiovascular disease and hemophilia A (see Human Therapies tab above).
SMaRTTM also can be used for second generation antibody production (in vivo antibody manufacturing), real-time molecular imaging, genomics and molecular evolution, and induced pluripotent stem cells (iPS cells) generation.
Please visit the Publications page under the Resources tab above to view publications on SMaRT™ technology in top tier scientific and medical journals.
The genetic information contained in a gene is “copied” first in the nucleus into a primary transcript or pre-messenger RNA (pre-mRNA) molecule, then processed into a shorter messenger RNA (mRNA), where segments of the pre-mRNA transcript called introns are removed and other segments, called exons, are joined together. This process is called cis-splicing which is catalyzed by the macromolecular enzymatic machinery called the “spliceosome”. The processed mRNA then is exported into cytoplasmic area of the cell, where it is translated into proteins.
As depicted in the illustration below, SMaRT™ repairs and reprograms genes by trans-splicing between two different RNA molecules: a target cellular pre-mRNA (present within the cell) and an exogenously delivered pre-trans-splicing molecule, i.e. PTM. The trans-splicing process is triggered by VIRxSYS’ PTM, a highly engineered RNA molecule which interferes with the normal cis-splicing process resulting in a composite mRNA molecule of therapeutic or diagnostic value.
VIRxSYS’s SMaRT™ technology provides an effective means to repair and reprogram specific pre-mRNAs and has broad applications (therapeutic and diagnostic), each governed by the nature of the coding sequences included in a specifically engineered PTM. PTMs that encode correct, functional genetic sequences or toxins have been used in RNA therapies to repair mutant mRNAs from genes associated with human disease or to kill diseased cells (e.g. cancer cells).
Because the coding domain can consist of one or more exons, a single PTM can be used to correct all the mutations in the region of the target RNA that is replaced.
| Schematic illustration above of a SMaRTTM reaction between the endogenous target pre-mRNA with a mutation and repair of this mutation through trans-splicing mediated by the delivered PTM. |
| Schematic illustration above of a SMaRTTM reprogramming reaction between highly abundant pre-mRNA transcript and a PTM encoding sequence for therapeutic value. |
Breadth of SMaRTTM Applications
PTMs containing reporter genes coding for fluorescent markers have also been developed. These PTMs have been used for real-time imaging of gene expression. Alternatively, PTMs containing mutant sequences or stop codons can be used to reduce wild-type gene expression and may be useful for target validation.
In addition to PTMs with binding domains comprised of sequences complementary to specific pre-mRNA targets, populations of PTMs with randomized binding domain sequences are capable of nonspecific trans-splicing, which is desirable in certain applications. Such non-specific trans-splicing can be used to identify alternative splice sites, and to map intron–exon junctions.
Additionally, such randomized trans-splicing could be used for molecular evolution by shuffling specific exon(s) in the PTM with other exons expressed by the genome. The resulting library of exon-shuffled proteins could then be selected for recombinant proteins with optimized or modified function
