Increased susceptibility of cytoplasmic over nuclear polyglutamine aggregates to autophagic degradation.

CNS neurons are endowed with the ability to recover from cytotoxic insults associated with the accumulation of proteinaceous aggregates in mouse models of polyglutamine disease, but the cellular mechanism underlying this phenomenon is unknown. Here, we show that autophagy is essential for the elimination of aggregated forms of mutant huntingtin and ataxin-1 from the cytoplasmic but not nuclear compartments. Human orthologs of yeast autophagy genes, molecular determinants of autophagic vacuole formation, are recruited to cytoplasmic but not nuclear inclusion bodies in vitro and in vivo. These data indicate that autophagy is a critical component of the cellular clearance of toxic protein aggregates and may help to explain why protein aggregates are more toxic when directed to the nucleus.

[1]  R. Kopito,et al.  Impairment of the ubiquitin-proteasome system by protein aggregation. , 2001, Science.

[2]  T. Ueno,et al.  LC3 conjugation system in mammalian autophagy , 2004, The International Journal of Biochemistry & Cell Biology.

[3]  H. Lehrach,et al.  Membrane filter assay for detection of amyloid-like polyglutamine-containing protein aggregates. , 1999, Methods in enzymology.

[4]  I. Kanazawa,et al.  Caspase activation during apoptotic cell death induced by expanded polyglutamine in N2a cells. , 1999, Neuroreport.

[5]  H. Zoghbi,et al.  Glutamine repeats and neurodegeneration. , 2000, Annual review of neuroscience.

[6]  D. Borchelt,et al.  Nuclear-targeting of mutant huntingtin fragments produces Huntington's disease-like phenotypes in transgenic mice. , 2004, Human molecular genetics.

[7]  D. Sulzer,et al.  Expanded CAG repeats in exon 1 of the Huntington's disease gene stimulate dopamine-mediated striatal neuron autophagy and degeneration. , 2001, Human molecular genetics.

[8]  L. Notterpek,et al.  Emerging Role for Autophagy in the Removal of Aggresomes in Schwann Cells , 2003, The Journal of Neuroscience.

[9]  J P Schellens,et al.  The phosphatidylinositol 3-kinase inhibitors wortmannin and LY294002 inhibit autophagy in isolated rat hepatocytes. , 1997, European journal of biochemistry.

[10]  Joshua T. Jones,et al.  Recombinant Dicer efficiently converts large dsRNAs into siRNAs suitable for gene silencing , 2003, Nature Biotechnology.

[11]  N. Mizushima,et al.  Formation of the ∼350-kDa Apg12-Apg5·Apg16 Multimeric Complex, Mediated by Apg16 Oligomerization, Is Essential for Autophagy in Yeast* , 2002, The Journal of Biological Chemistry.

[12]  R. Kopito,et al.  Aggresomes: A Cellular Response to Misfolded Proteins , 1998, The Journal of cell biology.

[13]  M. DiFiglia,et al.  Huntingtin Expression Stimulates Endosomal–Lysosomal Activity, Endosome Tubulation, and Autophagy , 2000, The Journal of Neuroscience.

[14]  Mark Turmaine,et al.  Formation of Neuronal Intranuclear Inclusions Underlies the Neurological Dysfunction in Mice Transgenic for the HD Mutation , 1997, Cell.

[15]  Daniel J Klionsky,et al.  A unified nomenclature for yeast autophagy-related genes. , 2003, Developmental cell.

[16]  Alexei Degterev,et al.  Diversity in the Mechanisms of Neuronal Cell Death , 2003, Neuron.

[17]  Mark R. Segal,et al.  Inclusion body formation reduces levels of mutant huntingtin and the risk of neuronal death , 2004, Nature.

[18]  K. Fischbeck,et al.  Intranuclear Inclusions of Expanded Polyglutamine Protein in Spinocerebellar Ataxia Type 3 , 1997, Neuron.

[19]  C. Ross,et al.  Protein aggregation and neurodegenerative disease , 2004, Nature Medicine.

[20]  Harry T Orr,et al.  SCA1 transgenic mice: A model for neurodegeneration caused by an expanded CAG trinucleotide repeat , 1995, Cell.

[21]  Fumiaki Tanaka,et al.  Aggresomes protect cells by enhancing the degradation of toxic polyglutamine-containing protein. , 2003, Human molecular genetics.

[22]  D. Sulzer,et al.  Autophagy in neurons: a review. , 2002, Histology and histopathology.

[23]  C. Ross,et al.  Nuclear Targeting of Mutant Huntingtin Increases Toxicity , 1999, Molecular and Cellular Neuroscience.

[24]  I. Kanazawa,et al.  Formic acid dissolves aggregates of an N-terminal huntingtin fragment containing an expanded polyglutamine tract: applying to quantification of protein components of the aggregates. , 2000, Biochemical and biophysical research communications.

[25]  Harry T Orr,et al.  Recovery from Polyglutamine-Induced Neurodegeneration in Conditional SCA1 Transgenic Mice , 2004, The Journal of Neuroscience.

[26]  H. Zoghbi,et al.  SCA1 molecular genetics: a history of a 13 year collaboration against glutamines. , 2001, Human molecular genetics.

[27]  P. Mathews,et al.  The Endosomal-Lysosomal System of Neurons in Alzheimer's Disease Pathogenesis: A Review , 2000, Neurochemical Research.

[28]  Hans Lehrach,et al.  Huntingtin-Encoded Polyglutamine Expansions Form Amyloid-like Protein Aggregates In Vitro and In Vivo , 1997, Cell.

[29]  J. Penney,et al.  Huntingtin localization in brains of normal and Huntington's disease patients , 1997, Annals of neurology.

[30]  A. Kakizuka,et al.  Protein precipitation: a common etiology in neurodegenerative disorders? , 1998, Trends in genetics : TIG.

[31]  R. Kopito,et al.  The Role of Multiubiquitination in Dislocation and Degradation of the α Subunit of the T Cell Antigen Receptor* , 1999, The Journal of Biological Chemistry.

[32]  Rahul S. Rajan,et al.  Specificity in intracellular protein aggregation and inclusion body formation , 2001, Proceedings of the National Academy of Sciences of the United States of America.

[33]  Rainer Duden,et al.  Aggregate-prone proteins with polyglutamine and polyalanine expansions are degraded by autophagy. , 2002, Human molecular genetics.

[34]  L. Greene,et al.  Expression of A53T Mutant But Not Wild-Type α-Synuclein in PC12 Cells Induces Alterations of the Ubiquitin-Dependent Degradation System, Loss of Dopamine Release, and Autophagic Cell Death , 2001, The Journal of Neuroscience.

[35]  Harry T Orr,et al.  Ataxin-1 Nuclear Localization and Aggregation Role in Polyglutamine-Induced Disease in SCA1 Transgenic Mice , 1998, Cell.

[36]  L. Thompson,et al.  Autophagy regulates the processing of amino terminal huntingtin fragments. , 2003, Human molecular genetics.

[37]  D A Agard,et al.  Dispersion, aberration and deconvolution in multi‐wavelength fluorescence images , 1996, Journal of microscopy.

[38]  R. Albin,et al.  Neurological abnormalities in a knock-in mouse model of Huntington's disease. , 2001, Human molecular genetics.

[39]  M. MacDonald,et al.  Amyloid Formation by Mutant Huntingtin: Threshold, Progressivity and Recruitment of Normal Polyglutamine Proteins , 1998, Somatic cell and molecular genetics.

[40]  R. Wetzel,et al.  Polyglutamine aggregation behavior in vitro supports a recruitment mechanism of cytotoxicity. , 2001, Journal of molecular biology.

[41]  E. Bennett,et al.  Global impairment of the ubiquitin-proteasome system by nuclear or cytoplasmic protein aggregates precedes inclusion body formation. , 2005, Molecular cell.

[42]  René Hen,et al.  Reversal of Neuropathology and Motor Dysfunction in a Conditional Model of Huntington's Disease , 2000, Cell.

[43]  Takeshi Noda,et al.  LC3, a mammalian homologue of yeast Apg8p, is localized in autophagosome membranes after processing , 2000, The EMBO journal.