Ion channel proteins produce the electrical impulses used to transmit information in the nervous system. Each neuron encodes a large complement of channel genes and the electrical character of the cell is dependent on the subset and quantity of channels that it expresses. In the mature nervous system, the cell must coordinately regulate the activity of ion channel genes to ensure that the properties of the cell do not drift. The Atkinson lab focuses on how channel gene expression is regulated in adult animals. They use the Drosophila model system because of the unusual molecular tools that it provides. The slo gene that they study encodes a BK type Ca2+-activated K+ channel which is highly conserved in structure and function from insects to mammals. The Drosophila slo gene has one of the best described transcriptional control regions of any channel gene. The Atkinson lab has shown that the slo gene responds to aberrant changes in neural excitability in a fashion predicted to restore normal activity. They use organic solvents as anesthetics to reduce neural excitability and observe that the animals up regulate slo gene expression. This change makes the animals resistant to further attempts at sedation (a behavior called tolerance). It is the transcriptional mechanics that link neural excitability to slo gene expression that the lab seeks to determine. The Atkinson lab has long studied the regulation of ion channel gene expression and has the tools and experience to address this question. The first objective is to use mutant analysis to identify transcription factors that up regulate slo after sedation. Flies carrying mutant transcription factor genes are tested to see if the mutation interferes with sedation-induced up regulation of slo. To date, two mutations have been identified and additional reasonable candidates exist. The second objective will be to determine if these factors act by directly by binding the slo promoter region or through an intermediary transcription factor. The chromatin immunoprecipitation assay will be used to see if the protein is physically present on the slo promoter region. Furthermore, by quantifying the amount of bound transcription factor in sedated and mocksedated animals, the lab will determine if sedation increases the binding of the transcription factor to its binding site. The third objective will be to determine the order of action of each transcription factor in the process. Previously, the lab used the chromatin immunoprecipitation assay to describe various epigenetic changes that occur across the slo promoter region following sedation. These changes are thought to be produced by transcription factor activity. Mutations in the responsible transcription factor gene are expected to block specific steps and interrupt the progression of these changes. By determining where each mutation truncates the process, the order of transcription factor activity can be determined. I
This project is designed from the ground up to have aspects that are readily accessible to undergraduate and high school students. This will enable the students the chance to join the lab and to perform important experimental work while they acquire the skills required for the technically difficult molecular portion of the project. Importantly, the undergraduates selected for the project will originate from both U.T. and from the minority institution, Texas A&M Kingsville. This project will be an important tool for encouraging minority participation in the life sciences.
