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Wild type huntingtin reduces the cellular toxicity of mutant huntingtin in mammalian cell models of Huntington's disease 总被引:5,自引:0,他引:5
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L. Ho R. Brown M. Maxwell A. Wyttenbach D. Rubinsztein 《Journal of medical genetics》2001,38(7):450-452
OBJECTIVES—Recent data suggest that wild type huntingtin can protect against apoptosis in the testis of mice expressing full length huntingtin transgenes with expanded CAG repeats. It is not clear if this protective effect was confined to particular cell types, or if wild type huntingtin exerted its protective effect in this model by simply reducing the formation of toxic proteolytic fragments from mutant huntingtin.
METHODS—We cotransfected neuronal (SK-N-SH, human neuroblastoma) and non-neuronal (COS-7, monkey kidney) cell lines with HD exon 1 (containing either 21 or 72 CAG repeats) construct DNA and either full length wild type huntingtin or pFLAG (control vector).
RESULTS—Full length wild type huntingtin significantly reduced cell death resulting from the mutant HD exon 1 fragments containing 72 CAG repeats in both cell lines. Wild type huntingtin did not significantly modulate cell death caused by transfection of HD exon 1 fragments containing 21 CAG repeats in either cell line.
CONCLUSIONS—Our results suggest that wild type huntingtin can significantly reduce the cellular toxicity of mutant HD exon 1 fragments in both neuronal and non-neuronal cell lines. This suggests that wild type huntingtin can be protective in different cell types and that it can act against the toxicity caused by a mutant huntingtin fragment as well as against a full length transgene.
Keywords: Huntington's disease; huntingtin; apoptosis 相似文献
METHODS—We cotransfected neuronal (SK-N-SH, human neuroblastoma) and non-neuronal (COS-7, monkey kidney) cell lines with HD exon 1 (containing either 21 or 72 CAG repeats) construct DNA and either full length wild type huntingtin or pFLAG (control vector).
RESULTS—Full length wild type huntingtin significantly reduced cell death resulting from the mutant HD exon 1 fragments containing 72 CAG repeats in both cell lines. Wild type huntingtin did not significantly modulate cell death caused by transfection of HD exon 1 fragments containing 21 CAG repeats in either cell line.
CONCLUSIONS—Our results suggest that wild type huntingtin can significantly reduce the cellular toxicity of mutant HD exon 1 fragments in both neuronal and non-neuronal cell lines. This suggests that wild type huntingtin can be protective in different cell types and that it can act against the toxicity caused by a mutant huntingtin fragment as well as against a full length transgene.
Keywords: Huntington's disease; huntingtin; apoptosis 相似文献
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Ehrnhoefer DE Duennwald M Markovic P Wacker JL Engemann S Roark M Legleiter J Marsh JL Thompson LM Lindquist S Muchowski PJ Wanker EE 《Human molecular genetics》2006,15(18):2743-2751
Huntington's disease (HD) is a progressive neurodegenerative disorder for which only symptomatic treatments of limited effectiveness are available. Preventing early misfolding steps and thereby aggregation of the polyglutamine (polyQ)-containing protein huntingtin (htt) in neurons of patients may represent an attractive therapeutic strategy to postpone the onset and progression of HD. Here, we demonstrate that the green tea polyphenol (-)-epigallocatechin-3-gallate (EGCG) potently inhibits the aggregation of mutant htt exon 1 protein in a dose-dependent manner. Dot-blot assays and atomic force microscopy studies revealed that EGCG modulates misfolding and oligomerization of mutant htt exon 1 protein in vitro, indicating that it interferes with very early events in the aggregation process. Also, EGCG significantly reduced polyQ-mediated htt protein aggregation and cytotoxicity in an yeast model of HD. When EGCG was fed to transgenic HD flies overexpressing a pathogenic htt exon 1 protein, photoreceptor degeneration and motor function improved. These results indicate that modulators of htt exon 1 misfolding and oligomerization like EGCG are likely to reduce polyQ-mediated toxicity in vivo. Our studies may provide the basis for the development of a novel pharmacotherapy for HD and related polyQ disorders. 相似文献
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Correlation between magnitude of CAG repeat length alterations and length of the paternal repeat in paternally inherited Huntington's disease 总被引:5,自引:0,他引:5
Anne Nørremølle Sven Asger Sørensen Kirsten Fenger Lis Hasholt 《Clinical genetics》1995,47(3):113-117
An increasing number of diseases are being found to be due to elongation of specific trinucleotide repeat sequences. Inverse correlation between the age at onset and the length of the repeat has been found in most of these. The elongated CAG repeat causing Huntington's disease is highly unstable when inherited from an affected father. In this study we found an average parent-to-offspring difference of +0.08 repeat units in maternally inherited repeats, significantly less than the average difference of +2.92 repeat units with paternal transmission. Large repeat expansions, of more than 5 repeat units, were seen only in paternally inherited cases. With paternal transmission the magnitude of repeat length alterations was directly correlated to increasing paternal repeat length. Increasing variation in repeat length among siblings was correlated to increasing average repeat length in the sibship in both maternally and paternally inherited HD. Comparison of the magnitude of repeat length alterations to parental age at the time of birth of the offspring showed no correlation. 相似文献
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Modregger J DiProspero NA Charles V Tagle DA Plomann M 《Human molecular genetics》2002,11(21):2547-2558
Huntington's disease (HD) is caused by a pathological expansion of a CAG repeat in the first exon of the gene coding for huntingtin, resulting in an abnormally long polyglutamine stretch. Despite its widespread expression, mutant huntingtin leads to selective neuronal loss in the striatum and cortex. Here we report that the neurospecific phosphoprotein PACSIN 1, which has been implicated as playing a central role in synaptic vesicle recycling, interacts with huntingtin via its C-terminal SH3 domain. Moreover, two other isoforms, PACSIN 2 and 3, which show a wider tissue distribution including the brain, do not interact with huntingtin despite a highly conserved SH3 domain. Furthermore, this interaction is repeat-length-dependent and is enhanced with mutant huntingtin, possibly causing the sequestration of PACSIN 1. Normally, PACSIN 1 is located along neurites and within synaptic boutons, but in HD patient neurons, there is a progressive loss of PACSIN 1 immunostaining in synaptic varicosities, beginning in presymptomatic and early-stage HD. Further, PACSIN 1 immunostaining of HD patient tissue reveals a more cytoplasmic distribution of the protein, with particular concentration in the perinuclear region coincident with mutant huntingtin. Thus, the specific interaction of huntingtin with the neuronal PACSIN isoform, PACSIN 1, and its altered intracellular distribution in pathological tissue, together with the observed differences in the binding behavior, suggest a role for PACSIN 1 during early stages of the selective neuropathology of HD. 相似文献
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Lloret A Dragileva E Teed A Espinola J Fossale E Gillis T Lopez E Myers RH MacDonald ME Wheeler VC 《Human molecular genetics》2006,15(12):2015-2024
Genetically precise models of Huntington's disease (HD), Hdh CAG knock-in mice, are powerful systems in which phenotypes associated with expanded HD CAG repeats are studied. To dissect the genetic pathways that underlie such phenotypes, we have generated Hdh(Q111) knock-in mouse lines that are congenic for C57BL/6, FVB/N and 129Sv inbred genetic backgrounds and investigated four Hdh(Q111) phenotypes in these three genetic backgrounds: the intergenerational instability of the HD CAG repeat and the striatal-specific somatic HD CAG repeat expansion, nuclear mutant huntingtin accumulation and intranuclear inclusion formation. Our results reveal increased intergenerational and somatic instability of the HD CAG repeat in C57BL/6 and FVB/N backgrounds compared with the 129Sv background. The accumulation of nuclear mutant huntingtin and the formation of intranuclear inclusions were fastest in the C57BL/6 background, slowest in the 129Sv background and intermediate in the FVB/N background. Inbred strain-specific differences were independent of constitutive HD CAG repeat size and did not correlate with Hdh mRNA levels. These data provide evidence for genetic modifiers of both intergenerational HD CAG repeat instability and striatal-specific phenotypes. Different relative contributions of C57BL/6 and 129Sv genetic backgrounds to the onset of nuclear mutant huntingtin and somatic HD CAG repeat expansion predict that the initiation of each of these two phenotypes is modified by different genes. Our findings set the stage for defining disease-related genetic pathways that will ultimately provide insight into disease mechanism. 相似文献
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Length-dependent gametic CAG repeat instability in the Huntington's disease knock-in mouse 总被引:1,自引:0,他引:1
Wheeler VC; Auerbach W; White JK; Srinidhi J; Auerbach A; Ryan A; Duyao MP; Vrbanac V; Weaver M; Gusella JF; Joyner AL; MacDonald ME 《Human molecular genetics》1999,8(1):115-122
The CAG repeats in the human Huntington's disease (HD) gene exhibit
striking length-dependent intergenerational instability, typically small
size increases or decreases of one to a few CAGs, but little variation in
somatic tissues. In a subset of male transmissions, larger size increases
occur to produce extreme HD alleles that display somatic instability and
cause juvenile onset of the disorder. Initial efforts to reproduce these
features in a mouse model transgenic for HD exon 1 with 48 CAG repeats
revealed only mild intergenerational instability ( approximately 2% of
meioses). A similar pattern was obtained when this repeat was inserted into
exon 1 of the mouse Hdh gene. However, lengthening the repeats in Hdh to 90
and 109 units produced a graded increase in the mutation frequency to
>70%, with instability being more evident in female transmissions. No
large jumps in CAG length were detected in either male or female
transmissions. Instead, size changes were modest increases and decreases,
with expansions typically emanating from males and contractions from
females. Limited CAG variation in the somatic tissues gave way to marked
mosaicism in liver and striatum for the longest repeats in older mice.
These results indicate that gametogenesis is the primary source of
inherited instability in the Hdh knock-in mouse, as it is in man, but that
the underlying repeat length-dependent mechanism, which may or may not be
related in the two species, operates at higher CAG numbers. Moreover, the
large CAG repeat increases seen in a subset of male HD transmissions are
not reproduced in the mouse, suggesting that these arise by a different
fundamental mechanism than the small size fluctuations that are frequent
during gametogenesis in both species.
相似文献
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Kuhn A Goldstein DR Hodges A Strand AD Sengstag T Kooperberg C Becanovic K Pouladi MA Sathasivam K Cha JH Hannan AJ Hayden MR Leavitt BR Dunnett SB Ferrante RJ Albin R Shelbourne P Delorenzi M Augood SJ Faull RL Olson JM Bates GP Jones L Luthi-Carter R 《Human molecular genetics》2007,16(15):1845-1861
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Cummings DM Milnerwood AJ Dallérac GM Waights V Brown JY Vatsavayai SC Hirst MC Murphy KP 《Human molecular genetics》2006,15(19):2856-2868
Predictive genetic testing for Huntington's disease (HD) has revealed early cognitive deficits in asymptomatic gene carriers, such as altered working memory, executive function and impaired recognition memory. The perirhinal cortex processes aspects of recognition memory and the underlying mechanism is believed to be long-term depression (LTD) of excitatory neurotransmission, the converse of long-term potentiation (LTP). We have used the R6/1 mouse model of HD to assess synaptic plasticity in the perirhinal cortex. We report here a progressive derailment of both LTD and short-term plasticity at perirhinal synapses. Layer II/III neurones gradually lose their ability to support LTD, show early nuclear localization of mutant huntingtin and display a progressive loss of membrane integrity (depolarization and loss of cell capacitance) accompanied by a reduction in the expression of D1 and D2 dopamine receptors visualized in layer I of the perirhinal cortex. Importantly, abnormalities in both short-term and long-term plasticity can be reversed by the introduction of a D2 dopamine receptor agonist (Quinpirole), suggesting that alterations in dopaminergic signalling may underlie early cognitive dysfunction in HD. 相似文献
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Correlation between the onset age of Huntington's disease and length of the trinucleotide repeat in IT-15 总被引:19,自引:7,他引:12
Stine O.Collin; Pleasant Nicole; Franz Mary L.; Abbott Margaret H.; Folstein Susan E.; Ross Christopher A. 《Human molecular genetics》1993,2(10):1547-1549
Huntington's disease (HD) is an autosomal dominant disorderwith a variable age of onset that is influenced by the sex ofthe affected parent. The recent recognition that HD is causedby an expanded triplet repeat suggests the possibility thatthe onset age may be predicted by the length of the repeat.This hypothesis was tested by assaying the length of the repeatin 114 individuals who were clinically diagnosed with HD andhad a known onset age. Every individual had an expanded allele.The range was from 36 to 82 repeats (mean = 48.4 ± 9.51)and larger than the normal range (6 to 31). The size of theexpanded allele was correlated with the age of onset (r = 0.65p <.0001). Despite the highly significant correlation, therepeat size explains less than half of the variance in onsetage. Furthermore, the age of onset cannot be predicted fromthe size of the triplet repeat, particularly if the number ofrepeats is in the smaller end of the expanded range. If therepeat Is 相似文献
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Huntington's disease (HD) is a neurodegenerative disorder caused by a polyglutamine repeat expansion in huntingtin. A newly developed bacterial artificial chromosome transgenic mouse model (BACHD) reproduces phenotypic features of HD including predominantly neuropil-associated protein aggregation and progressive motor dysfunction with selective neurodegenerative pathology. Motor dysfunction has been shown to precede neuropathology in BACHD mice. We therefore investigated the progression of synaptic pathology in pyramidal cells and interneurons of the superficial motor cortex of BACHD mice. Whole-cell patch clamp recordings were performed on layer 2/3 primary motor cortical pyramidal cells and parvalbumin interneurons from BACHD mice at 3 months, when the mice begin to demonstrate mild motor dysfunction, and at 6 months, when the motor dysfunction is more severe. Changes in synaptic variances were detectable at 3 months, and at 6 months BACHD mice display progressive synaptic pathology in the form of reduced cortical excitation and loss of inhibition onto pyramidal cells. These results suggest that progressive alterations of the superficial cortical circuitry may contribute to the decline of motor function in BACHD mice. The synaptic pathology occurs prior to neuronal degeneration and may therefore prove useful as a target for future therapeutic design. 相似文献
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Gohil VM Offner N Walker JA Sheth SA Fossale E Gusella JF MacDonald ME Neri C Mootha VK 《Human molecular genetics》2011,20(2):294-300
Defects in cellular energy metabolism represent an early feature in a variety of human neurodegenerative diseases. Recent studies have shown that targeting energy metabolism can protect against neuronal cell death in such diseases. Here, we show that meclizine, a clinically used drug that we have recently shown to silence oxidative metabolism, suppresses apoptotic cell death in a murine cellular model of polyglutamine (polyQ) toxicity. We further show that this protective effect extends to neuronal dystrophy and cell death in Caenorhabditis elegans and Drosophila melanogaster models of polyQ toxicity. Meclizine's mechanism of action is not attributable to its anti-histaminergic or anti-muscarinic activity, but rather, strongly correlates with its ability to suppress mitochondrial respiration. Since meclizine is an approved drug that crosses the blood-brain barrier, it may hold therapeutic potential in the treatment of polyQ toxicity disorders, such as Huntington's disease. 相似文献
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D'Amelio M Cavallucci V Middei S Marchetti C Pacioni S Ferri A Diamantini A De Zio D Carrara P Battistini L Moreno S Bacci A Ammassari-Teule M Marie H Cecconi F 《Nature neuroscience》2011,14(1):69-76
Synaptic loss is the best pathological correlate of the cognitive decline in Alzheimer's disease; however, the molecular mechanisms underlying synaptic failure are unknown. We found a non-apoptotic baseline caspase-3 activity in hippocampal dendritic spines and an enhancement of this activity at the onset of memory decline in the Tg2576-APPswe mouse model of Alzheimer's disease. In spines, caspase-3 activated calcineurin, which in turn triggered dephosphorylation and removal of the GluR1 subunit of AMPA-type receptor from postsynaptic sites. These molecular modifications led to alterations of glutamatergic synaptic transmission and plasticity and correlated with spine degeneration and a deficit in hippocampal-dependent memory. Notably, pharmacological inhibition of caspase-3 activity in Tg2576 mice rescued the observed Alzheimer-like phenotypes. Our results identify a previously unknown caspase-3-dependent mechanism that drives synaptic failure and contributes to cognitive dysfunction in Alzheimer's disease. These findings indicate that caspase-3 is a potential target for pharmacological therapy during early disease stages. 相似文献
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Shirendeb U Reddy AP Manczak M Calkins MJ Mao P Tagle DA Reddy PH 《Human molecular genetics》2011,20(7):1438-1455
The purpose of our study was to determine the relationship between mutant huntingtin (Htt) and mitochondrial dynamics in the progression of Huntington's disease (HD). We measured the mRNA levels of electron transport chain genes, and mitochondrial structural genes, Drp1 (dynamin-related protein 1), Fis1 (fission 1), Mfn1 (mitofusin 1), Mfn2 (mitofusin 2), Opa1 (optric atrophy 1), Tomm40 (translocase of outermembrane 40) and CypD (cyclophilin D) in grade III and grade IV HD patients and controls. The mutant Htt oligomers and the mitochondrial structural proteins were quantified in the striatum and frontal cortex of HD patients. Changes in expressions of the electron transport chain genes were found in HD patients and may represent a compensatory response to mitochondrial damage caused by mutant Htt. Increased expression of Drp1 and Fis1 and decreased expression of Mfn1, Mfn2, Opa1 and Tomm40 were found in HD patients relative to the controls. CypD was upregulated in HD patients, and this upregulation increased as HD progressed. Significantly increased immunoreactivity of 8-hydroxy-guanosine was found in the cortical specimens from stage III and IV HD patients relative to controls, suggesting increased oxidative DNA damage in HD patients. In contrast, significantly decreased immunoreactivities of cytochrome oxidase 1 and cytochrome b were found in HD patients relative to controls, indicating a loss of mitochondrial function in HD patients. Immunoblotting analysis revealed 15, 25 and 50 kDa mutant Htt oligomers in the brain specimens of HD patients. All oligomeric forms of mutant Htt were significantly increased in the cortical tissues of HD patients, and mutant Htt oligomers were found in the nucleus and in mitochondria. The increase in Drp1, Fis1 and CypD and the decrease in Mfn1 and Mfn2 may be responsible for abnormal mitochondrial dynamics that we found in the cortex of HD patients, and may contribute to neuronal damage in HD patients. The presence of mutant Htt oligomers in the nucleus of HD neurons and in mitochondria may disrupt neuronal functions. Based on these findings, we propose that mutant Htt in association with mitochondria imbalance and mitochondrial dynamics impairs axonal transport of mitochondria, decreases mitochondrial function and damages neurons in affected brain regions of HD patients. 相似文献