Role of Pannexin-1 in sensory systems

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Pannexin1 (Panx1) is one of three integral membrane proteins of the pannexin gene family characterized by distinct post-translational protein modifications, subcellular localization, and broad tissue distribution including the brain and sensory organs. Current knowledge is that Panx1 forms voltage gated channels. These channels appear involved in the cell-signaling cascades downstream of the purinergic, adrenergic, transient receptor potential vanilloid, and NMDA receptors. Further evidence suggests a complex regulation of Panx1 channels by elevated extracellular K+ and Zn2+, increased intracellular Ca2+, mechanical stimulation, voltage, caspase-mediated cleavage, redox regulation, kinases, NMDA stimulation, or changes in extracellular pH. Together, Panx1 channels represent a significant molecular hub with complex regulation and multiple physiological roles throughout the vertebrate body. The long-term objective of this research program is to understand the physiological role of Panx1 in synaptic transmission in the brain and sensory systems, with a focus on the visual system. The renewal of the current research program has three objectives testing distinct, but complementary aspects of Panx1 biology. They will be tested in vitro using cell-based approaches and in vivo using transgenic zebrafish generated by TALEN technology. Objective#1 inquires the regulatory role of phosphorylation as a "stop-go" signal when Panx1 is transported from the ER-Golgi complex to the cell membrane. Objective #2 inquires how extracellular pH regulates Panx1 channels when Panx1 has arrived at the cell surface. Objective #3 will investigate how genetic ablation of Panx1 genes in the zebrafish affects major signaling pathways, which impact sensory and motor behaviors. In the next five years, primary outcomes are poised to close significant knowledge gaps surrounding Panx1 channel function. In summary, I propose a highly synergistic and innovative approach using in vitro and in vivo methodology. The expected outcomes will provide novel mechanistic insight into Panx1 channel regulation and integration of signaling pathways converging on this molecular hub. Trainees will engage in this research at all levels and in the process acquire a broad skill set in a vibrant and challenging program. Finally, the unique zebrafish models used in the proposal will be made available for others who wish to pursue studies exploiting our animal models for investigating other fundamental biological questions, or for toxicology, drug screening, or biomedical/bioengineering research.