MicroRNA Alterations in a Tg501 Mouse Model of Prion Disease.

Janne M Toivonen,David Sanz-Rubio,Juan-Maria Torres,Rosario Osta,Óscar López-Pérez,Alba Marín-Moreno,Rosa Bolea,Juan J Badiola,Pilar Zaragoza,Juan-Carlos Espinosa,Inmaculada Martín-Burriel

doi:10.3390/biom10060908

Abstract

MicroRNAs (miRNAs) may contribute to the development and pathology of many neurodegenerative diseases, including prion diseases. They are also promising biomarker candidates due to their stability in body fluids. We investigated miRNA alterations in a Tg501 mouse model of prion diseases that expresses a transgene encoding the goat prion protein (PRNP). Tg501 mice intracranially inoculated with mouse-adapted goat scrapie were compared with age-matched, mock inoculated controls in preclinical and clinical stages. Small RNA sequencing from the cervical spinal cord indicated that miR-223-3p, miR-151-3p, and miR-144-5p were dysregulated in scrapie-inoculated animals before the onset of symptoms. In clinical-stage animals, 23 significant miRNA alterations were found. These miRNAs were predicted to modify the Kyoto Encyclopedia of Genes and Genomes (KEGG) pathways including prion disease, extracellular matrix interactions, glutaminergic synapse, axon guidance, and transforming growth factor-beta signaling. MicroRNAs miR-146a-5p (up in cervical spinal cord) and miR-342-3p (down in cervical spinal cord, cerebellum and plasma), both indicated in neurodegenerative diseases earlier, were verified by quantitative real-time polymerase chain reaction (qRT-PCR). Minimal changes observed before the disease onset suggests that most miRNA alterations observed here are driven by advanced prion-associated pathology, possibly limiting their use as diagnostic markers. However, the results encourage further mechanistic studies on miRNA-regulated pathways involved in these neurodegenerative conditions.

Highlights

MicroRNAs are short noncoding RNAs that regulate posttranscriptional gene expression by imperfect base pairing with target messenger RNAs, in most cases at the 3 untranslated region
The results indicate that whereas preclinical alterations in vivo are few, some clinical-stage miRNA alterations frequently reported in neurodegenerative diseases (NDD) are present in the used model and could serve as targets for subsequent mechanistic studies and as biomarker candidates for natural human and animal prion disease
Small RNA sequencing resulted in an average of approximately ten million reads per sample with an error probability of ≤ 0.001 in more than 97% of the base calls (Phred Q-score ≥ 30)

Summary

Introduction

MicroRNAs (miRNAs) are short noncoding RNAs that regulate posttranscriptional gene expression by imperfect base pairing with target messenger RNAs (mRNAs), in most cases at the 3 untranslated region. As translation from more than half of protein-coding genes in animals is regulated by miRNAs [1], it is not surprising that perturbations in miRNA expression or function are frequently associated with neurodegenerative diseases (NDD). Some miRNAs up-regulated sporadic Creutzfeldt-Jakob disease (sCJD) brain have been shown to be enriched in RNA induced silencing complexes (RISC), the essential machineries of miRNA function in vivo [4]. This suggests for the first time that the observed miRNA alterations are not merely bystanders but may bear relevance in prion disease-associated posttranslational perturbations

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Conclusion