| 1. |
- Smith, Ruben, et al.
(författare)
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Loss of SNAP-25 and rabphilin 3a in sensory-motor cortex in Huntington's disease.
- 2007
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Ingår i: Journal of Neurochemistry. - : Wiley. - 1471-4159 .- 0022-3042. ; 103:1, s. 115-123
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Tidskriftsartikel (refereegranskat)abstract
- Huntington’s disease (HD) is an autosomal dominant neurodegenerative disorder caused by a CAG-expansion in the gene encoding the protein huntingtin. The disease is characterized by progressive motor disturbances, cognitive defects, dementia, and weight loss. Using western blotting and immunohistochemistry we have assessed the expression levels and patterns of a number of proteins involved in neurotransmitter release in post-mortem frontal cortex samples from 10 HD cases with different disease grades. We report a loss of the soluble N-ethylmaleimide-sensitive factor attachment protein receptor (SNARE) protein, synaptosome-associated protein 25 (SNAP 25) in HD brains of grades I–IV. Moreover, in brains of grade III and IV we found a reduction in rabphilin 3a, a protein involved in vesicle docking and recycling. These losses appear to be specific and not due to a general loss of synapses in the HD cortex. Thus, levels of synaptobrevin II, syntaxin 1, rab3a or synaptophysin are unaltered in the same patient samples. SNAP 25 and rabphilin 3a are crucial for neurotransmitter release. Therefore, we suggest that a deficient pre-synaptic transmitter release may underlie some of the symptoms of HD.
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| 2. |
- Smith, Ruben, et al.
(författare)
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Mutant huntingtin interacts with {beta}-tubulin and disrupts vesicular transport and insulin secretion.
- 2009
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Ingår i: Human Molecular Genetics. - : Oxford University Press (OUP). - 0964-6906 .- 1460-2083. ; 18:20, s. 3942-3954
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Tidskriftsartikel (refereegranskat)abstract
- Huntington's disease is a severe progressive neurodegenerative disorder caused by a CAG-expansion in the IT15 gene, which encodes huntingtin. The disease primarily affects the neostriatum and cerebral cortex and also associates with increased incidence of diabetes. Here, we show that mutant huntingtin disrupts intracellular transport and insulin secretion by direct interference with microtubular beta-tubulin. We demonstrate that mutant huntingtin impairs glucose-stimulated insulin secretion in insulin-producing beta-cells, without altering stored levels of insulin. Using VSVG-YFP, we show that mutant huntingtin retards post-Golgi transport. Moreover, we demonstrate that the speed of insulin vesicle trafficking is reduced. Using immunoprecipitation of mutant and wild-type huntingtin in combination with mass spectrometry, we reveal an enhanced and aberrant interaction between mutant huntingtin and beta-tubulin, implying the underlying mechanism of impaired intracellular transport. Thus, our findings have revealed a novel pathogenetic process by which mutant huntingtin may disrupt hormone exocytosis from beta-cells and possibly impair vesicular transport in any cell that expresses the pathogenic protein.
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