Alternative splicing is a fundamental gene regulatory mechanism that allows cells to significantly diversify their protein products. Splicing defects, often caused by mutations that disrupt the function of RNA-binding proteins (RBPs), which regulate splicing, have increasingly been implicated in aging-related disorders including cancer and neurodegenerative disease. Yet, despite this emerging pattern, few splicing factors have been studied with regard to aging and aging-related disease. The long-term goal of this project is to begin to elucidate how aberrant splicing that results from the dysfunction of a highly conserved RBP, leads to abnormal aging phenotypes. To this end, the highly conserved splicing factor Caper will be used as a model. Caper is required for the development and maintenance of Drosophila sensory neurons, and for adult locomotor behavior. Our preliminary data show that caper dysfunction leads to a shortened lifespan and a decline in locomotor behavior that is exacerbated with age. Moreover, these aging phenotypes show a strong sex bias, where males are more affected than females. Such sex biases are often seen in aging-related diseases, but the underlying mechanism for such sex biases remains unknown. Though little is known about the function of the human caper ortholog, the human caper ortholog, RBM39, is implicated in cancer progression and is expressed throughout the nervous system. The research proposed within this application will test the following hypotheses: (1) Caper regulates the maintenance of neurons in the adult brain and nervous system; (2) caper is differentially spliced in males compared to females; (3) Caper regulates sex-specific splicing during aging. Using the highly tractable model, Drosophila, we will utilize immunofluorescence to examine various markers of brain anatomy, apoptosis and mitochondrial markers over time in adult flies to determine if caper dysfunction results in neurodegeneration. We will use differential gene expression and spliceform analyses to determine whether caper itself is differentially spliced in aging male versus female flies, and if caper regulates differential splicing of other genes in aging male versus female flies. Finally, we will perform a pilot genetic screen to identify genes that interact with caper to regulate aging phenotypes. The outcomes of this study will establish the foundation for a more comprehensive research program aimed at using caper as a model for aging and sex biases in aging-related disease. Since aberrant alternative splicing has emerged as a common theme in various aging disorders, the knowledge gained from this study has broad implications for understanding and treating such disorders.
Aging related diseases represent one of the leading public health challenges of our time. While the precise cause of many aging-related diseases remains unknown, recently, proteins termed splicing factors have been specifically implicated in aging-related disorders, including cancer and, neurodegenerative disorders such as amyotrophic lateral sclerosis. The research proposed within this application will help understand why inappropriate function of splicing factors leads to aging-related disease and will begin to explain why aging- related diseases often display a sex bias.
