Sensitive biochemical aggregate detection reveals aggregation onset before symptom development in cellular and murine models of Huntington's disease.
A CAG-repeat gene expansion translated into a pathogenic polyglutamine stretch at the N-terminus of huntingtin triggers Huntington's Disease. Mutated huntingtin is predicted to adopt toxic properties mainly if aggregation-prone N-terminal fragments are released by proteolysis. Huntingtin-aggregates are indeed a major hallmark of this disorder and could represent useful markers of disease-onset or progression. We designed a simple method for qualitative and quantitative characterization of aggregates. For this, we analyzed samples from in vitro and in vivo Huntington's Disease models by agarose gel electrophoresis and showed that in the brain of transgenic mice huntingtin-aggregates became larger as a function of disease progression. This appears to be a property of cytoplasmic but not nuclear aggregates. In cell cultures, treatment with Congo Red inhibited aggregate growth but not total load. Finally, we showed that in primary striatal neurons and in brains of R6/2 and HdhQ150 mice, the presence of aggregates preceded initiation of any other functional deficits. This observation argues for a pathogenic role of huntingtin-aggregation in Huntington's Disease. Our results emphasize that thorough analysis of huntingtin metabolism and aggregation is now feasible, thus significantly improving the power of studies assessing therapies designed to lower huntingtin levels or to interfere with its aggregation.
Weiss
Andreas
A
Neuroscience Discovery, Novartis Institutes for BioMedical Research, Basel, Switzerland.
Klein
Corinna
C
Woodman
Ben
B
Sathasivam
Kirupa
K
Bibel
Miriam
M
Régulier
Etienne
E
Bates
Gillian P
GP
Paganetti
Paolo
P
D000367:Age Factors; D000818:Animals; D001921:Brain / Q000378:metabolism / Q000473:pathology / Q000648:ultrastructure; D002478:Cells, Cultured; D003342:Corpus Striatum / Q000473:pathology; D004195:Disease Models, Animal; D015180:Electrophoresis, Gel, Two-Dimensional / Q000379:methods; D004622:Embryo, Mammalian; D005260:Female; D000071058:Huntingtin Protein; D006816:Huntington Disease / Q000378:metabolism / Q000473:pathology* / Q000503:physiopathology; D051379:Mice; D008822:Mice, Transgenic; D009154:Mutation / Q000502:physiology; D009419:Nerve Tissue Proteins / Q000235:genetics / Q000378:metabolism*; D009474:Neurons / Q000502:physiology*; D009687:Nuclear Proteins / Q000235:genetics / Q000378:metabolism*; D011247:Pregnancy; D013347:Subcellular Fractions / Q000378:metabolism; D013997:Time Factors; D014162:Transfection / Q000379:methods; D019680:Trinucleotide Repeat Expansion / Q000235:genetics
C506812:Htt protein, mouse; D000071058:Huntingtin Protein; D009419:Nerve Tissue Proteins; D009687:Nuclear Proteins