HDAC6 and the intersection between the UPS, autophagy, and neurodegeneration

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DESCRIPTION (provided by applicant): The long-term objective of this project is to characterize the molecular machinery responsible for eliminating misfolded, neurotoxic proteins so that they may be exploited for therapeutic intervention for neurodegenerative diseases such as spinobulbar muscular atrophy (SBMA). SBMA is a hereditary disease characterized by progressive loss of motor neurons in the brainstem and spinal cord. SBMA is caused by trinucleotide (CAG) repeat expansion in the first exon of the androgen receptor gene leading to polyglutamine expansion in AR protein. Like other polyglutamine diseases, SBMA is characterized by accumulation of misfolded protein aggregates in degenerating neurons. Histone deacetylase 6 (HDAC6) is a microtubule-associated deacetylase with intrinsic polyubiquitin-binding activity. We recently determined that over-expression of HDAC6 rescues degeneration in SBMA flies, flies with proteasome mutations, and other fly models of neurodegenerative disease. HDAC6 rescues degeneration by facilitating the degradation of aberrant, ubiquitinated protein by the autophagy-lysosomal system. In this application, we will (1) test specific hypotheses regarding the molecular mechanism whereby HDAC6 facilitates autophagic degradation of aberrant protein, (2) determine the therapeutic potential of HDAC6 in mammals, and (3) use the power of fly genetics to gain unanticipated insights into the role of HDAC6 in cellular management of misfolded protein stress. PUBLIC HEALTH RELEVANCE: Histone deacetylase 6 contributes to elimination of misfolded proteins from neurons and protects against neurodegeneration. It is not known how HDAC6 functions. This application seeks to understand the mechanism of HDAC6 function so that it may be exploited for therapeutics development.