The role of miRNA biogenesis and decay in spinal muscular atrophy
Molecular Biology and Physiology of Neurons and Glial Cells
Final Report Abstract
The aim of this proposal was to understand miRNA function and regulation in motor neurons and their associated disease, spinal muscular atrophy (SMA). Previously, we discovered that a small subset of miRNAs accounts for over 80% of miRNA expression in motor neurons, and these miRNAs are regulated by neuronal activity and autophagy. Analyzing transcriptomic profiles using RNA-seq after manipulating miRNA levels via moto-miR knockdown and overexpression is a critical investigative approach to uncover dysregulated pathways contributing to the pathophysiology of SMA. To investigate the role of these miRNAs in motor neuron physiology and elucidate potential molecular mechanisms underlying miRNA regulation, we performed transcriptome and proteome analyses using SMA, HET and wild-type E13.5-derived motor neurons. Additionally, we specifically inhibited or overexpressed the three most significant miRNAs. One of the candidates identified in our study was PRPF4. By participating in the intricate process of pre-mRNA splicing, PRPF4 contributes to the proper formation of mature mRNAs, which subsequently dictate the synthesis of functional proteins. Dysregulation or alteration in PRPF4 levels, influenced by moto-miR inhibition, can potentially impact the accuracy and fidelity of pre-mRNA splicing, leading to disruptions in gene expression and contributing to disease-related mechanisms such as SMA. Therefore, understanding the regulation of PRPF4 by moto-miRs provides valuable insights into the intricate molecular processes underlying gene expression and cellular function. In the context of SMA, where there is a deficiency in SMN protein leading to disrupted splicing and mRNA processing, PRPF4's role in pre-mRNA splicing becomes highly relevant. Dysregulated splicing is a hallmark of SMA pathology, contributing to the misregulation of crucial genes involved in motor neuron survival and function. The observed alteration in PRPF4 expression following moto-miR inhibition suggests that it might be a key player in the complex network of molecular events contributing to SMA pathogenesis. However, validating alterations in PRPF4 protein levels, as well as assessing changes in other candidate proteins following moto-miR modulation through miRNA mimics and inhibitors, posed challenges during validation through Western blotting. Furthermore, modifications in mRNA expression require validation within our transcriptomic datasets.
Publications
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Mitochondrial defects in the respiratory complex I contribute to impaired translational initiation via ROS and energy homeostasis in SMA motor neurons. Acta Neuropathologica Communications, 8(1).
Thelen, Maximilian Paul; Wirth, Brunhilde & Kye, Min Jeong
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The Role of RNA Binding Proteins for Local mRNA Translation: Implications in Neurological Disorders. Frontiers in Molecular Biosciences, 6.
Thelen, Maximilian Paul & Kye, Min Jeong
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Twenty-Five Years of Spinal Muscular Atrophy Research: From Phenotype to Genotype to Therapy, and What Comes Next. Annual Review of Genomics and Human Genetics, 21(1), 231-261.
Wirth, Brunhilde; Karakaya, Mert; Kye, Min Jeong & Mendoza-Ferreira, Natalia
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Mitochondrial Dysfunction in Spinal Muscular Atrophy. International Journal of Molecular Sciences, 23(18), 10878.
Zilio, Eleonora; Piano, Valentina & Wirth, Brunhilde
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S-Glutathionylation and S-Nitrosylation in Mitochondria: Focus on Homeostasis and Neurodegenerative Diseases. International Journal of Molecular Sciences, 23(24), 15849.
Vrettou, Sofia & Wirth, Brunhilde
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CLUH maintains functional mitochondria and translation in motoneuronal axons and prevents peripheral neuropathy. Science Advances, 10(22).
Zaninello, Marta; Schlegel, Tim; Nolte, Hendrik; Pirzada, Mujeeb; Savino, Elisa; Barth, Esther; Klein, Ines; Wüstenberg, Hauke; Uddin, Tesmin; Wolff, Lisa; Wirth, Brunhilde; Lehmann, Helmar C.; Cioni, Jean-Michel; Langer, Thomas & Rugarli, Elena I.
