Article type: Research Article
Authors: Vodicka, Petr | Lim, Junghyun | Williams, Dana T. | Kegel, Kimberly B. | Chase, Kathryn | Park, Hyunsun | Marchionini, Deanna | Wilkinson, Stephen | Mead, Tania | Birch, Helen | Yates, Dawn | Lyons, Kathy | Dominguez, Celia | Beconi, Maria | Yue, Zhenyu | Aronin, Neil | DiFiglia, Marian
Affiliations: Department of Neurology, Massachusetts General Hospital and Harvard Medical School, Charlestown, MA, USA | Department of Neurology, Department of Neuroscience, Friedman Brain Institute, Icahn School of Medicine at Mount Sinai, Leon and Norma Hess Center for Science and Medicine, New York, NY, USA | Departments of Medicine and Cell Biology, University of Massachusetts, Worcester, MA, USA | CHDI Management/CHDI Foundation, Los Angeles, CA, USA | BioFocus DPI Limited, Chesterford Research Park, UK | Independent consultant
Note: [] Correspondence to: Petr Vodicka, Department of Neurology, Massachusetts General Hospital, 114 16th Street, Charlestown, MA 02129, USA. Tel.: +1 6177265762; Fax: +1 6177261264; E-mail: pvodicka@partners.org
Note: [] Present address: Retrophin Inc., Cambridge, MA, USA.
Abstract: Background: Increasing mutant huntingtin (mHTT) clearance through the autophagy pathway may be a way to treat Huntington's disease (HD). Tools to manipulate and measure autophagy flux in brain in vivo are not well established. Objective: To examine the in vivo pharmacokinetics and pharmacodynamics of the lysosomal inhibitor chloroquine (CQ) and the levels of selected autophagy markers to determine usefulness of CQ as a tool to study autophagy flux in brain. Methods: Intraperitoneal injections of CQ were administered to WT and HDQ175/Q175 mice. CQ levels were measured by LC-MS/MS in WT brain, muscle and blood at 4 to 24 hours after the last dose. Two methods of tissue preparation were used to detect by Western blot levels of the macroautophagy markers LC3II and p62, the chaperone mediated autophagy receptor LAMP-2A and the late endosome/lysosomal marker RAB7. Results: Following peripheral administration, CQ levels were highest in muscle and declined rapidly between 4 and 24 hours. In the brain, CQ levels were greater in the cortex than striatum, and levels persisted up to 24 hours post-injection. CQ treatment induced changes in LC3II and p62 that were variable across regions and tissue preparations. HDQ175/Q175 mice exposed to CQ had variable but diminished levels of LC3II, p62 and LAMP-2A, and increased levels of RAB7. Higher levels of mHTT were found in the membrane compartment of CQ treated HD mice. Conclusion: Our findings suggest that the response of brain to CQ treatment, a blocker of autophagy flux, is variable and not as robust as it has been demonstrated in vitro, suggesting that CQ treatment has limitations for modulating autophagy flux in vivo. Alternative methods, compounds, and technologies need to be developed to further investigate autophagy flux in vivo, especially in the brain.
DOI: 10.3233/JHD-130081
Journal: Journal of Huntington's Disease, vol. 3, no. 2, pp. 159-174, 2014
