Abstract
Spinal and bulbar muscular atrophy (SBMA) is one of eight inherited neurodegenerative diseases known to be caused by CAG repeat expansion. The expansion results in an expanded polyglutamine tract, which likely confers a novel, toxic function to the affected protein. Cell culture and transgenic mouse studies have implicated the nucleus as a site for pathogenesis, suggesting that a critical nuclear factor or process is disrupted by the polyglutamine expansion. In this report we present evidence that CREB-binding protein (CBP), a transcriptional co-activator that orchestrates nuclear response to a variety of cell signaling cascades, is incorporated into nuclear inclusions formed by polyglutamine-containing proteins in cultured cells, transgenic mice and tissue from patients with SBMA. We also show CBP incorporation into nuclear inclusions formed in a cell culture model of another polyglutamine disease, spinocerebellar ataxia type 3. We present evidence that soluble levels of CBP are reduced in cells expressing expanded polyglutamine despite increased levels of CBP mRNA. Finally, we demonstrate that over-expression of CBP rescues cells from polyglutamine-mediated toxicity in neuronal cell culture. These data support a CBP-sequestration model of polyglutamine expansion disease.
Publication types
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Research Support, U.S. Gov't, P.H.S.
MeSH terms
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Animals
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Ataxin-3
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CREB-Binding Protein
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Cell Death / drug effects
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Cell Line
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Cell Nucleus / metabolism
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Cells, Cultured
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DNA-Binding Proteins
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Fungal Proteins / metabolism
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Green Fluorescent Proteins
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HeLa Cells
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Humans
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Luciferases / metabolism
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Luminescent Proteins / metabolism
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Machado-Joseph Disease / genetics
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Machado-Joseph Disease / metabolism
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Male
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Mice
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Mice, Transgenic
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Muscular Atrophy, Spinal / genetics
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Muscular Atrophy, Spinal / metabolism
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Nerve Tissue Proteins / metabolism
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Nuclear Proteins / metabolism*
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Peptides / metabolism*
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Peptides / pharmacology
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RNA, Messenger / metabolism
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Repressor Proteins
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Saccharomyces cerevisiae Proteins*
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Scrotum / metabolism
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Tetrazolium Salts / pharmacology
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Thiazoles / pharmacology
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Time Factors
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Trans-Activators / metabolism*
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Transcription Factors / metabolism
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Transcription, Genetic
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Trinucleotide Repeat Expansion*
Substances
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DNA-Binding Proteins
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Fungal Proteins
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GAL4 protein, S cerevisiae
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Luminescent Proteins
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Nerve Tissue Proteins
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Nuclear Proteins
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Peptides
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RNA, Messenger
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Repressor Proteins
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Saccharomyces cerevisiae Proteins
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Tetrazolium Salts
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Thiazoles
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Trans-Activators
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Transcription Factors
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Green Fluorescent Proteins
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polyglutamine
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Luciferases
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CREB-Binding Protein
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CREBBP protein, human
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Crebbp protein, mouse
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ATXN3 protein, human
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Ataxin-3
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Atxn3 protein, mouse
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thiazolyl blue