Presentation Title

Rescue of Canine XL-MTM MicroRNA Transcriptome via Gene Transfer

Faculty Mentor

David L Mack

Start Date

23-11-2019 8:00 AM

End Date

23-11-2019 8:45 AM

Location

59

Session

poster 1

Type of Presentation

Poster

Subject Area

biological_agricultural_sciences

Abstract

MicroRNAs (miRNAs) are 20-30 nucleotide long non-coding RNA sequences that assist in post-transcriptional regulation by binding to mRNA and either competitively inhibiting ribosomal activity or marking the mRNA for destruction via the Argonaute family of proteins. Because miRNAs are critical in maintaining normal temporal and spatial patterning of certain mRNA transcripts, much of the pathology resulting from neuromuscular diseases may be caused by abnormal miRNA expression. This can occur even if the disease is caused by a mutation that does not directly affect miRNA as is the case in X-linked myotubular myopathy (XL-MTM), a mutation in Myotubularin 1. Myotubularin 1 encodes for a lipid phosphatase which contains no miRNA in its introns. While a loss of function mutation in Myotubularin 1 would have no direct, primary effect on miRNA transcripts or miRNA encoding genes, there are likely downstream, secondary effects on miRNA levels caused by Myotubularin’s involvement with signal transduction pathways. Our group has previously demonstrated that systemic gene transfer delivered by an AAV vector can restore muscle structure and function in a canine model of XL-MTM. RNA sequencing of muscle biopsies taken during this study showed that the transcriptome of XL-MTM dogs treated with gene therapy were corrected to near wild-type (WT) expression levels. We conducted a preliminary longitudinal study employing small RNA sequencing of muscle biopsies from various time points during the course of treatment and confirmed that the miRNA transcriptome returns to WT levels in a treatment dose-dependent manner. We also demonstrate that this rescue follows a period of dose-dependent deviation from WT miRNA expression levels, which may reveal critical information about the disease pathology of XL-MTM in particular and miRNA rescue via gene therapy in general.

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Nov 23rd, 8:00 AM Nov 23rd, 8:45 AM

Rescue of Canine XL-MTM MicroRNA Transcriptome via Gene Transfer

59

MicroRNAs (miRNAs) are 20-30 nucleotide long non-coding RNA sequences that assist in post-transcriptional regulation by binding to mRNA and either competitively inhibiting ribosomal activity or marking the mRNA for destruction via the Argonaute family of proteins. Because miRNAs are critical in maintaining normal temporal and spatial patterning of certain mRNA transcripts, much of the pathology resulting from neuromuscular diseases may be caused by abnormal miRNA expression. This can occur even if the disease is caused by a mutation that does not directly affect miRNA as is the case in X-linked myotubular myopathy (XL-MTM), a mutation in Myotubularin 1. Myotubularin 1 encodes for a lipid phosphatase which contains no miRNA in its introns. While a loss of function mutation in Myotubularin 1 would have no direct, primary effect on miRNA transcripts or miRNA encoding genes, there are likely downstream, secondary effects on miRNA levels caused by Myotubularin’s involvement with signal transduction pathways. Our group has previously demonstrated that systemic gene transfer delivered by an AAV vector can restore muscle structure and function in a canine model of XL-MTM. RNA sequencing of muscle biopsies taken during this study showed that the transcriptome of XL-MTM dogs treated with gene therapy were corrected to near wild-type (WT) expression levels. We conducted a preliminary longitudinal study employing small RNA sequencing of muscle biopsies from various time points during the course of treatment and confirmed that the miRNA transcriptome returns to WT levels in a treatment dose-dependent manner. We also demonstrate that this rescue follows a period of dose-dependent deviation from WT miRNA expression levels, which may reveal critical information about the disease pathology of XL-MTM in particular and miRNA rescue via gene therapy in general.