Knockdown and replacement therapy mediated by artificial mirtrons in spinocerebellar ataxia 7
Abstract
HJ Curtis, Y Seow, MJA Wood and MA Varela,
Nucleic acids research , Jul 27 2017
We evaluate a knockdown-replacement strategy mediated by mirtrons as an alternative to allele-specific silencing using spinocerebellar ataxia 7 (SCA7) as a model. Mirtrons are introns that form pre-microRNA hairpins after splicing, producing RNAi effectors not processed by Drosha. Mirtron mimics may therefore avoid saturation of the canonical processing pathway. This method combines gene silencing mediated by an artificial mirtron with delivery of a functional copy of the gene such that both elements of the therapy are always expressed concurrently, minimizing the potential for undesirable effects and preserving wild-type function. This mutation- and single nucleotide polymorphism-independent method could be crucial in dominant diseases that feature both gain- and loss-of-function pathologies or have a heterogeneous genetic background. Here we develop mirtrons against ataxin 7 with silencing efficacy comparable to shRNAs, and introduce silent mutations into an ataxin 7 transgene such that it is resistant to their effect. We successfully express the transgene and one mirtron together from a single construct. Hence, we show that this method can be used to silence the endogenous allele of ataxin 7 and replace it with an exogenous copy of the gene, highlighting the efficacy and transferability across patient genotypes of this approach.
What does all this exactly mean for patients. Is this type of gene manipulation close to being used in a clinical setting with patients.
Rilusol, the generic name for Rilutek, offers the first medication of any type for symptom control of many strains of ataxia. If it lives up to its promise, it could be the difference between walking the dog and having the dog come along while you ride in a motorized chair. This is huge and you need to inform your doctor about it