Shari L. Wiseman - US grants

DESCRIPTION (provided by applicant): Proper neuronal function requires precise temporal and spatial regulation of protein levels, and this is largely occurs via control over the translation of mRNAs into new proteins and the degradation of existing proteins by the ubiquitin-proteasome system (UPS). Studies using pharmacological inhibitors of protein synthesis and the UPS have indicated that these processes are critical for long-term synaptic plasticity and memory consolidation, and regulation of these processes is likely involved in the plasticity of brain reward systems that mediates the development of addiction. Emerging evidence suggests that stabilization of long-term plasticity requires gene-specific, rather than global, translational control and coordination or balance of protein synthesis and degradation processes. The mechanisms by which this occurs, the specific changes in protein expression that result, and the consequences of these processes for drug-mediated behavior are critical issues that this proposal seeks to elucidate by investigating the role and regulation of eukaryotic elongation factor-2 kinase, a Ca2????dependent protein kinase that exerts translational control by phosphorylating eukaryotic elongation factor-2 (eEF-2) and inhibiting translation at the elongation step. Previous studies and preliminary data suggest that EF2K is a central mediator both of gene-specific translation and the coordination of protein synthesis and degradation, although the mechanisms and consequences of these functions remain to be elucidated. To this end, the proposed research will characterize the mechanisms by which EF2K is targeted for UPS-mediated degradation in response to stimulation, the specific regulation that EF2K exerts on patterns of protein expression, and the role of EF2K in locomotor sensitization to cocaine. These studies will advance understanding of the role of gene-specific modes of translation and coordination of protein synthesis and degradation, as well as the mechanisms of plasticity mediated by drugs of abuse, potentially enabling the development of novel therapeutics. PUBLIC HEALTH RELEVANCE: The goal of this proposal is to characterize the function of gene-specific translational control and coordination of protein synthesis and degradation in cocaine-mediated behavior, the mechanisms by which these processes occur, and their specific consequences for patterns of protein expression. The long-term changes in neural reward circuitry that underlie addiction are thought to engage these molecular processes, and by characterizing them in detail, novel approaches to the treatment of addiction may be developed.

DESCRIPTION (provided by applicant): Huntington's disease (HD) is a neurodegenerative disorder marked by debilitating motor, cognitive, and emotional symptoms. It is caused by a dominantly inherited CAG triplet repeat expansion in the Huntingtin (HTT) gene, which gives rise to HD pathology both via toxic gains of function of the mutant HTT protein and interference with the critical functions of wild-type HTT. This proposal seeks to better elucidate how the expression of the wild-type human HTT gene is regulated by a hominid-specific long noncoding RNA (lncRNA) that has been linked to autism, highlighting its potential importance in the brain. Preliminary data indicate that the lncRNA is expressed in the human brain in a similar regional enrichment pattern as HTT mRNA, and that it increases human HTT expression in transgenic mice expressing both human genes. Cell culture assays will investigate whether an intronic transposable element in the HTT gene is necessary and sufficient to confer its regulation by the lncRNA, and to identify the chromatin remodeling processes that are recruited by the lncRNA to increase HTT transcription. The human lncRNA and HTT genes will then be expressed in transgenic mice to reconstitute the genetic regulatory system. Experiments in these mice will examine the effects of lncRNA expression on molecular, cellular, and behavioral processes that are enhanced by wild-type HTT and impaired in HD models. Specifically, neuronal gene transcription, apoptosis, vesicle motility, anxiety-like behaviors, and cognitive function in the Morris water maze will be assayed. Illuminating this novel, hominid-specific mechanism controlling the expression of wild-type HTT will provide a more thorough understanding of the normal functions that HD pathology impinges upon, and may thereby advance the development of improved therapies.