The Role of miR-218 in Motor Neurons

• Main Author: Reichenstein, Irit
• Format: Dissertation
• Language: English
• Published: ProQuest Dissertations & Theses 01-01-2017
• Subjects: Alzheimers disease; Amyotrophic lateral sclerosis; Automation; Binding sites; Biosynthesis; Developmental biology; Embryos; Enzymes; Gene expression; Genomes; Hybridization; Metabolism; Nervous system; Neurodegeneration; Neurons; Neurosciences; Potassium; Spinal cord; Stains & staining; Stem cells
• ISBN: 9798802709290
• DOI: 10.34933/wis.000267

microRNAs (miRNAs) are key posttranscriptional regulators, involved in a variety of processes in the central nervous system (CNS). miRNAs play roles in neurodevelopment and are crucial for the proper homeostatic function of neurons in the adult. To uncover the role of specific miRNAs in motor neurons, I have mapped the expression of all known miRNAs in human and mouse and discovered that only a small subset is expressed in motor neurons. One of the most abundant miRNAs, miR-218, is expressed in a highly specific manner from early stages of motor neuron development and onto adulthood. In this study, I explore the function of miR-218 in motor neurons and demonstrate that a principal function for this miRNA is in controlling neuronal excitability. Using patch clamp studies I demonstrate that miR-218 controls intrinsic neuronal properties including membrane resting potential, rheobase, input resistance and firing frequency. I further show that miR-218 regulates network activity, by monitoring intracellular calcium dynamics in motor neurons. Thus, miR-218 overexpression results in hyper-excitability, whereas miR-218 knockdown silences neuronal electric activity. I also characterize by next-generation sequencing and functional rescue experiments new effectors downstream of miR-218. These include the two potassium channels, Kv4.2 and Kv10.1 and the GABA transporters GAT1 and GAT3. Because of its selective expression in motor neurons, miR-218 activity uncovers a previously unappreciated facet of motor neuron specificity that may be particularly susceptible to failure in disease.