Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UMLS:C0013421 (dystonia)
 8,418 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

A mutation of the DYT1 gene, which codes for torsinA, has been identified as the cause of one form of autosomal dominantly inherited dystonia. TorsinA immunohistochemistry was used to examine a case of DYT1, and several cases of non-DYT1, dystonia. No evidence was found for alterations of immunoreactivity at the light microscopic level, specifically neither cytoplasmic aggregations nor colocalization of torsinA immunoreactivity with a marker for endoplasmic reticulum. These findings contrast with results of recent cell culture studies of torsinA.
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PMID:TorsinA immunoreactivity in brains of patients with DYT1 and non-DYT1 dystonia. 1178 16

Two mutations in torsinA have been identified to date, both of which are associated with an autosomal dominant form of early onset-dystonia. It has been reported previously that expression of the more common mutation, a deletion of one of a pair of glutamates (deltaE302/303) produces intracellular, endoplasmic reticulum-derived inclusions in cultured cells. In this study we have replicated these previous results and have additionally looked at the localization of the more recently described deltaF323-Y328 mutation. We show that the localization of this latter mutation is similar to wild type torsinA and unlike the deltaE302/303 mutation. This data suggests that the formation of intracellular inclusions is specific to deltaE302/303 and not a property shared by deltaF323-Y328.
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PMID:Normal localization of deltaF323-Y328 mutant torsinA in transfected human cells. 1209 39

Deletion of a single glutamate in torsinA correlates with early-onset dystonia, the most severe form of a neurological disorder characterized by uncontrollable muscle contractions. TorsinA is targeted to the ER (endoplasmic reticulum) in eukaryotic cells. We investigated the processing and membrane association of torsinA and the dystonia-associated Glu-deletion mutant (torsinAdeltaE). We found that the signal sequence of torsinA (residues 1-20 from the 40 amino-acid long N-terminal hydrophobic region) is cleaved in Drosophila S2 cells, as shown by the N-terminal sequencing after partial protein purification. TorsinA is not secreted from S2 cells. Consistently, sodium carbonate extraction and Triton X-114 treatment showed that torsinA is associated with the ER membrane in CHO (Chinese-hamster ovary) cells. In contrast, a variant of torsinA that contains the native signal sequence without the hydrophobic region Ile24-Pro40 does not associate with the membranes in CHO cells, and a truncated torsinA without the 40 N-terminal amino acids is secreted in the S2 culture. Thus the 20-amino-acid-long hydrophobic segment in torsinA, which remains at the N-terminus after signal-peptide cleavage, is responsible for the membrane anchoring of torsinA. TorsinAdeltaE showed similar cleavage of the 20 N-terminal amino acids and membrane association properties similar to wild-type torsinA but, unlike the wild-type, torsinAdeltaE was not secreted in the S2 culture even after deletion of the membrane-anchoring segment. This indicates that the dystonia-associated mutation produces a structurally distinct, possibly misfolded, form of torsinA, which cannot be properly processed in the secretory pathway of eukaryotic cells.
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PMID:Characterization of human torsinA and its dystonia-associated mutant form. 1278 Mar 49

Primary dystonia is a disease characterized by involuntary twisting movements caused by CNS dysfunction without underlying histopathology. DYT1 dystonia is a form of primary dystonia caused by an in-frame GAG deletion (DeltaE302/3) in the TOR1A gene that encodes the endoplasmic reticulum luminal protein torsinA. We show that torsinA is also present in the nuclear envelope (NE), where it appears to interact with substrate, and that the DeltaE302/3 mutation causes a striking redistribution of torsinA from the endoplasmic reticulum to the NE. In addition, DeltaE302/3-torsinA recruits WT torsinA to the NE, potentially providing insight into an understanding of the dominant inheritance of the disease. DYT1 dystonia appears to be a previously uncharacterized NE disease and the first, to our knowledge, to selectively affect CNS function.
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PMID:Mislocalization to the nuclear envelope: an effect of the dystonia-causing torsinA mutation. 1518 29

Torsion dystonia-1 (DYT1) dystonia, the most common inherited form of dystonia, is caused by a three base pair deletion that eliminates a single amino acid from the disease protein, torsinA. TorsinA is an "AAA" protein thought to reside in the endoplasmic reticulum (ER), yet both its cellular function and the basis for neuronal dysfunction in DYT1 remain unknown. A clue to disease pathogenesis is the fact that mutant, but not wild-type, torsinA forms membranous inclusions in cell culture. To explore the pathobiology of DYT1 dystonia, we generated PC12 neural cell lines that inducibly express wild-type or mutant torsinA. Although in this model torsinA displays some properties consistent with ER localization, mutant torsinA also accumulates in the nuclear envelope (NE), a structure contiguous with cytoplasmic ER. Consistent with this, membranous inclusions formed by mutant torsinA are shown to derive not from the ER, as thought previously, but from the NE. We demonstrate further that torsinA forms different disulfide-linked complexes that may be linked functionally to subcellular localization in the NE versus cytoplasmic ER. Despite mutant TA accumulation in NE structures, nucleocytoplasmic transport of a reporter protein was unaffected. These findings, together with parallel studies failing to demonstrate perturbation of ER function, implicate the NE as a primary site of dysfunction in DYT1. DYT1 dystonia can be added to the growing list of inherited neurological disorders involving the NE.
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PMID:Aberrant cellular behavior of mutant torsinA implicates nuclear envelope dysfunction in DYT1 dystonia. 1502 51

TorsinA is a novel protein identified in the search for mutations underlying the human neurologic movement disorder, early onset torsion dystonia. Relatively little is understood about the normal function of torsinA or the physiological effects of the codon deletion associated with most cases of disease. Overexpression of wild-type torsinA in cultured cells by DNA transfection results in a reticular distribution of immunoreactive protein that co-localizes with endoplasmic reticulum resident chaperones, while the dystonia-related mutant form accumulates within concentric membrane whorls and nuclear-associated membrane stacks. In this study we examined the biogenesis of mutant torsinA-positive membrane inclusions using tetracycline-regulated herpes simplex virus amplicon vectors. At low expression levels, mutant torsinA was localized predominantly around the nucleus, while at high levels it was also concentrated within cytosolic spheroid inclusions. In contrast, the distribution of wild-type torsinA did not vary, appearing diffuse and reticular at all expression levels. These observations are consistent with descriptions of inducible membrane synthesis in other systems in which cytosolic membrane whorls are derived from multilayered membrane stacks that first form around the nuclear envelope. These results also suggest that formation of mutant torsinA-positive inclusions occurs at high expression levels in culture, whereas the perinuclear accumulation of the mutant protein is present even at low expression levels that are more likely to resemble those of the endogenous protein. These nuclear-associated membrane structures enriched in mutant torsinA may therefore be of greater relevance to understanding how the dystonia-related mutation compromises cellular physiology.
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PMID:Perinuclear biogenesis of mutant torsin-A inclusions in cultured cells infected with tetracycline-regulated herpes simplex virus type 1 amplicon vectors. 1509 79

Early-onset torsion dystonia, a CNS-based movement disorder, is usually associated with a single amino acid deletion (Delta E302/303) in the protein torsinA. TorsinA is an AAA+ ATPase in the endoplasmic reticulum, but what it does is unknown. Here, we use torsinA mutants with defects in ATP hydrolysis (E171Q, ATP-bound) and ATP binding (K108A, ATP-free) to probe torsinA's normal cellular function. Surprisingly, ATP-bound torsinA is recruited to the nuclear envelope (NE) of transfected cells, where it alters connections between inner and outer nuclear membranes. In contrast, ATP-free torsinA is diffusely distributed throughout the endoplasmic reticulum and has no effect on the NE. Among AAA+ ATPases, affinity for substrates is high in the ATP-bound and low in the ATP-free state, leading us to propose that component(s) of the NE may be substrates for torsinA. We also find that the disease-promoting Delta E302/303 mutant is in the NE, and that this relocalization, as well as the mutant's previously described ability to induce membranous inclusions, is eliminated by the K108A ATP-binding mutation. These results suggest that changes in interactions involving torsinA in the NE could be important for the pathogenesis of dystonia and point to torsinA and related proteins as a class of ATPases that may operate in the NE.
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PMID:TorsinA in the nuclear envelope. 1518 29

Early onset generalized dystonia is a severe form of primary dystonia linked to a mutation of the DYT1(TOR1A) gene on chromosome 9q34. DYT1 gene codifies for human torsinA, an AAA+ ATPase associated with the membranes of endoplasmic reticulum (ER) and the synaptic vesicles and proposed to be involved in trafficking of tubular-vesicular membrane through neuronal processes. In this study, the presence and the intracellular distribution of torsinA protein in SH-SY5Y neuroblastoma cells were evaluated by immunofluorescence and Western blot analysis following differentiation with retinoic acid and BDNF. Protein expression was then inhibited by transient antisense transfection and the possible effect on neurite outgrowth was observed. In SH-SY5Y cells torsinA, with an apparent MW of 38 kDa, is endogenously present and distributed, with a punctate pattern, in the cytosol and along the neurites. The protein showed high intensity of immunoreactivity in the neurite varicosities and was partially co-localized with vesicles markers. Terminally differentiated cells showed an increase of protein expression. Oligonucleotide antisense treatment induced a significant response to differentiating stimuli, lead to sprouting of longer neurites and increase in growth cone areas. A relationship between torsinA and tau protein, which is involved in axon elongation and establishment of neuronal polarity, was demonstrated by co-immunoprecipitation experiments. These findings suggest that torsinA, throughout the interaction with microtubule associated proteins, may contribute to control neurite outgrowth and could be involved in maintaining cell polarity.
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PMID:TorsinA negatively controls neurite outgrowth of SH-SY5Y human neuronal cell line. 1515 63

Most cases of early-onset torsion dystonia (EOTD) are caused by a deletion of one glutamic acid in the carboxyl terminus of a protein named torsinA. The mutation causes the protein to aggregate in perinuclear inclusions as opposed to the endoplasmic reticulum localization of the wild-type protein. Although there is increasing evidence that dysfunction of the dopamine system is implicated in the development of EOTD, the biological function of torsinA and its relation to dopaminergic neurotransmission has remained unexplored. Here, we show that torsinA can regulate the cellular trafficking of the dopamine transporter, as well as other polytopic membrane-bound proteins, including G protein-coupled receptors, transporters, and ion channels. This effect was prevented by mutating the ATP-binding site in torsinA. The dystonia-associated torsinA deletion mutant (DeltaE-torsinA) did not have any effect on the cell surface distribution of polytopic membrane-associated proteins, suggesting that the mutation linked with EOTD results in a loss of function. However, a mutation in the ATP-binding site in DeltaE-torsinA reversed the aggregate phenotype associated with the mutant. Moreover, the deletion mutant acts as a dominant-negative of wild-type torsinA through a mechanism presumably involving association of wild-type and mutant torsinA. Taken together, our results provide evidence for a functional role for torsinA and a loss of function and a dominant-negative phenotype of the DeltaE-torsinA mutation. These properties may contribute to the autosomal dominant nature of the condition.
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PMID:Effect of torsinA on membrane proteins reveals a loss of function and a dominant-negative phenotype of the dystonia-associated DeltaE-torsinA mutant. 1550 7

Most cases of early-onset torsion dystonia are associated with a mutation in the DYT1 gene that results in the loss of a glutamic acid residue in the carboxy terminus of the encoded protein, torsinA. When overexpressed in cultured cells, wild-type torsinA distributes diffusely throughout the endoplasmic reticulum (ER), while the dystonia-related mutant, torsinADeltaE, accumulates within multilamellar membrane inclusions. Here we show that inclusion formation requires the addition of an N-linked oligosaccharide to one of two asparagine residues within the ATP-binding domain of the mutant protein. In the absence of this modification, overexpressed torsinADeltaE was localized diffusely throughout the cell in a reticular pattern resembling that of wild-type torsinA. In contrast, the localization of wild-type torsinA did not appear to vary with its glycosylation state. These results thus indicate that torsinADeltaE must achieve a specific conformation to induce formation of intracellular membrane inclusions.
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PMID:Inhibition of N-linked glycosylation prevents inclusion formation by the dystonia-related mutant form of torsinA. 1555 20


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