Alternative Splicing Modulates the Activity of CaV3.1. an Ion Channel Gene Involved in Spinocerebellar Ataxia, Epilepsy, and Autism Spectrum Disorders

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PROJECT SUMMARY/ABSTRACT The central nervous system comprises the tissues and cells with the highest rate of alternative splicing in the body, and RNA-binding proteins play a major functional role in neurons. To better understand the contribution of RNA splicing to nerve cell biology, and to help elucidate the function that splicing plays in neuron physiology and neurologic disorders it is necessary to characterize how the inclusion or skipping of specific exons modulates the physiological properties of molecules — such as ion channels — that are critical for neuronal function, and to characterize how these splicing events are regulated at the cellular and molecular level. Our long-term goal is to understand the molecular mechanisms regulating protein-RNA networks that control alternative splicing in the brain, and how they relate to the biology of neurons and to disorders of the nervous system. The objective of this proposal is to study how alternative splicing of CaV3.1, a voltage-gated Calcium channel that significantly contributes to the regulation of cell membrane excitability — particularly in muscle and neurons — and that is mutated in patients with spinocerebellar ataxia-42 (SCA42) is regulated in different neuron cell types, and how it may contributes to the modulation of channel activity. The central hypothesis of this proposal is that neuronal cell type-specific alternative splicing of CaV3.1 at the C-terminus shapes the physiological properties of this voltage-gated ion channel. In Aim 1 we will test the hypothesis that CaV3.1 alternatively spliced exons are differentially expressed in different neuronal cell types in the brain. To tackle this question, we have developed an RNAseq-based bioinformatics pipeline that will allow us to interrogate differential splicing between neuronal subclasses defined at different hierarchical levels. This methodology will not only provide a snapshot of the alternative splicing landscape of CaV3.1 in different neuronal subclasses in the brain, but it will also allow us to generate predictions on how these alternative splicing events are regulated. In Aim 2 we will test the hypothesis that alternative splicing at the C-terminus significantly contributes to the regulation of the physiological activity of this ion channel. Since several disease-associated mutations in CaV3.1 map to alternatively spliced exons, understanding how alternative splicing modulates channel activity is critical. Since patients with CaV3.1-associated pathologies display defects in Calcium current properties, understanding how alternative splicing may modulate the biological functions of CaV3.1 and how this modulation is regulated, may have broad and significant clinical implications in spinocerebellar ataxia, epilepsy, and autism spectrum disorders, and it may inform the design of novel therapeutic strategies. Moreover, this project will provide both undergraduate and graduate students with a unique opportunity to learn the fundamentals of molecular biology and biomedical research and help them in their pursue of a career in the biomedical field.