Liberation of Intracellular Zinc and Neuronal Cell Death

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Dysregulation of cellular Zn2+ has been tightly linked to neuronal injury in neurodegenerative conditions present in stroke, trauma and epilepsy. Our group first suggested that Zn2+ released from intracellular binding proteins by oxidative and nitrosative stress represents a critical and ubiquitous trigger for the activation of neuronal cell death processes in these and other neurological disorders. In work performed during the first funding period of this grant, we characterized cell death signaling cascades resulting from ntracellular Zn2+ liberation, and demonstrated in vivo injurious intraneuronal accumulation of this metal in the absence of synaptic Zn2+ release. The completion and publication of nearly all of the originally proposed experiments has allowed us to continue to expand our work in this novel and exciting area of research. In this competitive renewal application we propose: 1) To establish the mechanism by which intracellular Zn2* release activates specific MAPK-dependent cell death signaling pathways. With these studies, we aim to characterize the process by which Zn2+ can initiate divergent signaling processes. 2) To investigate the factors that modulate Zn2+-regulated neuronal gene expression in order to resolve conditions affecting Zn2+ buffering systems and, ultimately, Zn2+ cellular homeostasis. These studies aim to elucidate the fundamental properties of Zn2+-mediated gene expression in neurons, a relatively unexplored but critically important area of research. And 3) to determine the molecular cell-death pathway activated by intracellular Zn2+ release in vivo and uncover the endogenous stimulus for the liberation of this metal. Our long-term objectives are to characterize in detail the molecular signaling cascades leading to neuronal cell death following the liberation of intracellular Zn2+. As such, results of these studies will likely generate new avenues for therapeutic intervention in the large number of neurodegenerative disorders associated with oxidative and nitrosative injury. Relevance to public health. Results from these studies will provide fundamental information about the cellular mechanisms responsible for a host of neurological disorders, including stroke, trauma and epilepsy. With this information, we hope to uncover novel therapeutic strategies to prevent or halt the progression of these and other neurodegenerative conditions.