Autophagy Activation by Transcription Factor EB (TFEB) in Striatum of HDQ175/Q7 Mice

• Published in: Journal of Huntington's disease Vol. 5; no. 3; pp. 249 - 260
• Main Authors: Vodicka, Petr, Chase, Kathryn, Iuliano, Maria, Tousley, Adelaide, Valentine, Dana T., Sapp, Ellen, Kegel-Gleason, Kimberly B., Sena-Esteves, Miguel, Aronin, Neil, DiFiglia, Marian
• Format: Journal Article
• Language: English
• Published: London, England SAGE Publications 01.10.2016; IOS Press
• Subjects: Animals; Autophagy - genetics; Basic Helix-Loop-Helix Leucine Zipper Transcription Factors - genetics; Basic Helix-Loop-Helix Leucine Zipper Transcription Factors - metabolism; Cathepsin D - metabolism; Cell Count; Corpus Striatum - metabolism; Disease Models, Animal; Dopamine and cAMP-Regulated Phosphoprotein 32 - metabolism; Gene Expression Regulation - genetics; HSC70 Heat-Shock Proteins - metabolism; Humans; Huntingtin Protein - genetics; Huntington Disease - genetics; Huntington Disease - pathology; Lysosomal-Associated Membrane Protein 2 - metabolism; Mice; Mice, Transgenic; Mutation - genetics; Nerve Tissue Proteins - genetics; Nerve Tissue Proteins - metabolism; Phosphoric Diester Hydrolases - metabolism; rab GTP-Binding Proteins - metabolism; Research Report; autophagy; GRP78/BiP; striatum; huntingtin; neurodegeneration; TFEB; Huntington’s disease; LC3; Adeno associated virus
• ISSN: 1879-6397; 1879-6397; 1879-6400
• DOI: 10.3233/JHD-160211

Background: Mutant huntingtin (mHTT) is encoded by the Huntington’s disease (HD) gene and its accumulation in the brain contributes to HD pathogenesis. Reducing mHTT levels through activation of the autophagosome-lysosomal pathway may have therapeutic benefit. Transcription factor EB (TFEB) regulates lysosome biogenesis and autophagy. Objective: To examine if increasing TFEB protein levels in HD mouse striatum induces autophagy and influences mHTT levels. Methods: We introduced cDNA encoding TFEB with an HA tag (TFEB-HA) under the control of neuron specific synapsin 1 promoter into the striatum of 3 month old HDQ175/Q7 mice using adeno-associated virus AAV2/9. The levels of exogenous TFEB were analyzed using qPCR and Western blot. Proteins involved in autophagy, levels of huntingtin, and striatal-enriched proteins were examined using biochemical and/or immunohistochemical methods. Results: In HD mice expressing TFEB-HA, HA immunoreactivity distributed throughout the striatum in neuronal cell bodies and processes and preferentially in neuronal nuclei and overlapped with a loss of DARPP32 immunoreactivity. TFEB-HA mRNA and protein were detected in striatal lysates. There were increased levels of proteins involved with autophagosome/lysosome activity including LAMP-2A, LC3II, and cathepsin D and reduced levels of mutant HTT and the striatal enriched proteins DARPP32 and PDE10A. Compared to WT mice, HDQ175/Q7 mice had elevated levels of the ER stress protein GRP78/BiP and with TFEB-HA expression, increased levels of the astrocyte marker GFAP and pro-caspase 3. Conclusion: These results suggest that TFEB expression in the striatum of HDQ175/Q7 mice stimulates autophagy and lysosome activity, and lowers mHTT, but may also increase a neuronal stress response.