The N17 domain mitigates nuclear toxicity in a novel zebrafish Huntington's disease model. Mol Neurodegener 2015 Dec 09;10:67
Date
12/10/2015Pubmed ID
26645399Pubmed Central ID
PMC4673728DOI
10.1186/s13024-015-0063-2Scopus ID
2-s2.0-84949559773 (requires institutional sign-in at Scopus site) 36 CitationsAbstract
BACKGROUND: Although the genetic cause for Huntington's disease (HD) has been known for over 20 years, the mechanisms that cause the neurotoxicity and behavioral symptoms of this disease are not well understood. One hypothesis is that N-terminal fragments of the HTT protein are the causative agents in HD and that peptide sequences adjacent to the poly-glutamine (Q) repeats modify its toxicity. Here we test the function of the N-terminal 17 amino acids (N17) in the context of the exon 1 fragment of HTT in a novel, inducible zebrafish model of HD.
RESULTS: Deletion of N17 coupled with 97Q expansion (mHTT-ΔN17-exon1) resulted in a robust, rapidly progressing movement deficit, while fish with intact N17 and 97Q expansion (mHTT-exon1) have more delayed-onset movement deficits with slower progression. The level of mHTT-ΔN17-exon1 protein was significantly higher than mHTT-exon1, although the mRNA level of each transgene was marginally different, suggesting that N17 may regulate HTT protein stability in vivo. In addition, cell lineage specific induction of the mHTT-ΔN17-exon1 transgene in neurons was sufficient to recapitulate the consequences of ubiquitous transgene expression. Within neurons, accelerated nuclear accumulation of the toxic HTT fragment was observed in mHTT-ΔN17-exon1 fish, demonstrating that N17 also plays an important role in sub-cellular localization in vivo.
CONCLUSIONS: We have developed a novel, inducible zebrafish model of HD. These animals exhibit a progressive movement deficit reminiscent of that seen in other animal models and human patients. Deletion of the N17 terminal amino acids of the huntingtin fragment results in an accelerated HD-like phenotype that may be due to enhanced protein stability and nuclear accumulation of HTT. These transgenic lines will provide a valuable new tool to study mechanisms of HD at the behavioral, cellular, and molecular levels. Future experiments will be focused on identifying genetic modifiers, mechanisms and therapeutics that alleviate polyQ aggregation in the nucleus of neurons.
Author List
Veldman MB, Rios-Galdamez Y, Lu XH, Gu X, Qin W, Li S, Yang XW, Lin SAuthor
Matthew B. Veldman PhD Assistant Professor in the Cell Biology, Neurobiology and Anatomy department at Medical College of WisconsinMESH terms used to index this publication - Major topics in bold
AnimalsAnimals, Genetically Modified
Behavior, Animal
Brain
Disease Models, Animal
Exons
Huntington Disease
Mutation
Neurons
Nuclear Proteins
Zebrafish
