CFTR: Neuronal roles for a multifunctional transporter

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Neurons rely on their electrical activity to generate signals and to communicate with other neurons. Like batteries in a flashlight, ion gradients power neurons and enable the transmission of information. Here, we study the function of cystic fibrosis transmembrane regulator (CFTR), a chloride channel that when mutated, causes the disease cystic fibrosis. Because of this link to disease, CFTR has been heavily studied in the context of systems that produce the life-threatening effects of cystic fibrosis such as the respiratory and digestive systems. In contrast, little is known about the function of CFTR in the brain where it is also found. It is known that one role of CFTR in neurons is to regulate the chloride ion gradient. This new project will take a deep dive into the regulation and unique functions of CFTR in neurons. One of the major objectives of this project is to identify the neuron-specific proteins with which CFTR interacts. This research will provide insight into the role of CFTR in the brain and a scaffold of neuronal protein interaction information which will form the basis of further studies into this multifunctional ion channel. A middle school neuroscience outreach program called GeauxNeuro has been implemented that provides a diverse group of neuroscience graduates students at LSU with outreach opportunities and brings neuroscience to public school students in Louisiana. Although CFTR expression has been demonstrated for neurons in the brain and spinal cord, the role of this Cl- channel in neuronal function is poorly understood. The expression of CFTR in neurons is becoming recognized, however, the PI could identify no more than 15 studies that directly address CFTR function in neurons. This proposal focuses on the role of CFTR in the management of neuronal cytosolic Cl- levels and in regulating synaptic function. In Aim 1 both the localization and regulation of CFTR will be elucidated. Subcellular localization of CFTR will be examined using immunocytochemistry at the electron microscope level because physiological experiments suggest that CFTR is expressed in the membranes of acidic organelles. Electrophysiological and molecular biology experiments are designed to discover the mechanistic links between CFTR and an NO-dependent release of internal Cl-. In Aim 2, similar methods will be used to investigate the functional significance of CFTR and two established interactors (anoctamin 1 and syntaxin 1A) to determine the role these interactions play in pre- and postsynaptic operations. CFTR is well known to have highly cell-type specific interactions with other proteins and as such, Aim 3 defines an immunoprecipitation-mass spectroscopy-based strategy for identifying novel neuronal binding partners for this multi-functional protein.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.