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Disrupted microRNA expression caused by Mecp2 loss in a mouse model of Rett syndrome
Rocio G Urdinguio1, Agustin F Fernandez, Pilar Lopez-Nieva
1Cancer Epigenetics and Biology Program (PEBC); Bellvitge Biomedical Research Institute, L’Hospitalet, Barcelona, Catalonia, Spain.
Abstract:
MicroRNAs (miRNAs) are short non-coding RNA molecules that regulate post-transcriptional gene expression. They influence a wide range of physiological functions, including neuronal processes, and are regulated by various mechanisms, such as DNA methylation. This epigenetic mark is recognized by transcriptional regulators such as the methyl CpG binding protein Mecp2. Rett syndrome is a complex neurological disorder that has been associated with mutations in the gene coding for Mecp2. Thus, we examined the possible miRNA misregulation caused by Mecp2 absence in a mouse model of Rett syndrome. Using miRNA expression microarrays, we observed that the brain of Rett syndrome mice undergoes a disruption of the expression profiles of miRNAs. Among the significantly altered miRNAs (26%, 65 of 245), overall downregulation of these transcripts was the most common feature (71%), whilst the remaining 30% were upregulated. Further validation by quantitative RT-PCR demonstrated that the most commonly disrupted miRNAs were miR-146a, miR-146b, miR-130, miR-122a, miR-342 and miR-409 (downregulated), and miR-29b, miR329, miR-199b, miR-382, miR-296, miR-221 and miR-92 (upregulated). Most importantly, transfection of miR-146a in a neuroblastoma cell line caused the downregulation of IL-1 receptor-associated kinase 1 (Irak1) levels, suggesting that the identified defect of miR-146a in Rett syndrome mice brains might be responsible for the observed upregulation of Irak1 in this model of the human disease. Overall, we provide another level of molecular deregulation occurring in Rett syndrome that might be useful for understanding the disease and for designing targeted therapies.
Insights
Rett syndrome, a neurological disorder linked to Mecp2 mutations, shows altered microRNA (miRNA) expression in the brain. Downregulation of specific miRNAs, like miR-146a, may contribute to disease pathology by affecting gene targets such as Irak1.
Area of Science:
- Neuroscience
- Epigenetics
- Molecular Biology
Background:
- MicroRNAs (miRNAs) are key regulators of gene expression, influencing numerous physiological processes, including neuronal function.
- Epigenetic mechanisms, such as DNA methylation, control miRNA expression, and the methyl CpG binding protein Mecp2 plays a crucial role in this regulation.
- Rett syndrome is a severe neurological disorder caused by mutations in the MECP2 gene.
Purpose of the Study:
- To investigate microRNA (miRNA) misregulation in the brain of a mouse model of Rett syndrome, focusing on the role of Mecp2.
- To identify specific miRNAs that are differentially expressed due to Mecp2 absence and explore their potential contribution to Rett syndrome pathogenesis.
Main Methods:
- Utilized miRNA expression microarrays to profile miRNA expression in the brains of Rett syndrome mice and control littermates.
- Performed quantitative RT-PCR for validation of selected miRNA expression changes.
- Conducted cell line transfections to assess the functional impact of specific miRNAs on target gene expression.
Main Results:
- Observed significant disruption in miRNA expression profiles in the brains of Rett syndrome mice, with 26% of analyzed miRNAs showing altered expression.
- Found that miRNA downregulation was the predominant feature (71% of altered miRNAs), while 30% were upregulated.
- Identified specific miRNAs, including miR-146a, miR-146b, and miR-130, as significantly downregulated, and miR-29b and miR-221 as upregulated.
- Demonstrated that miR-146a transfection reduced Irak1 levels in a neuroblastoma cell line, suggesting a mechanistic link between miR-146a deficiency and Irak1 upregulation in Rett syndrome.
Conclusions:
- Mecp2 absence in a mouse model of Rett syndrome leads to widespread miRNA dysregulation in the brain.
- The identified miRNA alterations, particularly the downregulation of miR-146a, represent a novel layer of molecular pathology in Rett syndrome.
- These findings offer potential insights into disease mechanisms and suggest that targeting specific miRNAs could be a therapeutic strategy for Rett syndrome.
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