Machado–Joseph Disease Gene Product Identified in Lymphocytes and Brain

doi:10.1006/bbrc.1997.6484

Biochemical and Biophysical Research Communications

Volume 233, Issue 2, 17 April 1997, Pages 476-479

https://doi.org/10.1006/bbrc.1997.6484 Get rights and content

Abstract

Machado–Joseph disease (MJD) is associated with the expansion of an unstable CAG repeat. The existence of an abnormal gene product in MJD was previously suggested with the expanded polyglutamine stretch-specific antibody. However, the product of the normal allele has not previously been identified. We generated monoclonal antibodies against the fusion protein (codon 225-310) of the MJD gene product and then identified the MJD1 gene product in normal lymphoblastoid cells as a ≈50-kDa protein by immunoblot analysis. The electrophoretic mobility differences among the normal allele products corresponds to the molecular size difference produced by the polyglutamine stretch and the polymorphism at the C-terminus. Moreover, abnormal immunoreactive bands which were larger than the normal ones were found as a ≈60-kDa protein exclusively in the MJD samples. The cytoplasm and the nuclei of neurons and glial cells were stained by these antibodies with immunocytochemistry. As in other CAG repeat diseases, the abnormal and normal allele products were almost equally expressed in lymphoblastoid cells and the brain of MJD patients.

References (21)

K. Ide et al.
Biochem. Biophys Res. Commun.
(1995)
R.N. Rosenberg
Mov. Disord.
(1992)
Y. Takiyama et al.
Nature Genet.
(1993)
Y. Kawaguchi et al.
Nature Genet.
(1994)
K. Nishiyama et al.
Ann. Neurol.
(1996)
A.R. La Spada et al.
Nature
(1991)
Cell
(1993)
H.T. Orr et al.
Nature Genet.
(1993)
R. Koide et al.
Nature Genet.
(1994)
S. Nagafuchi et al.
Nature Genet.
(1994)

There are more references available in the full text version of this article.

Cited by (38)

Overexpression of FKH-2/FOXG1 is neuroprotective in a C. elegans model of Machado-Joseph disease
2021, Experimental Neurology
Citation Excerpt :
The CAG repeat number in healthy individuals is between 10 and 51, whereas in MJD patients, this repeat is expanded to 55–87 (Maciel et al., 2001; Cummings and Zoghbi, 2000). The mutated ATXN3 gene when translated contains an abnormal poly-Q tract within the ataxin-3 protein (Kawaguchi et al., 1994; Wang et al., 1997). This abnormal expansion in ATXN3 gene leads to misfolding of ATXN3 inducing numerous harmful impacts and disrupting cellular homeostasis (Shao and Diamond, 2007; Da Silva et al., 2019).
Machado-Joseph disease (MJD), also known as spinocerebellar ataxia type 3 (SCA3), is the most common form of dominantly inherited ataxia worldwide. This disease is caused by an expanded CAG repeat in the coding region of ATXN3. Due to our incomplete understanding of mechanisms and molecular pathways related to this disease, there are no therapies that successfully treat core MJD patients. Therefore, the identification of new candidate targets related to this disease is needed.
In this study, we performed a large-scale RNA interference (RNAi) screen of 387 transcription factor genes leading to the identification of several modifiers (suppressors and enhancers) of impaired motility phenotypes in a mutant ATXN3 transgenic C. elegans model. We showed that inactivation of one particular gene, fkh-2/FOXG1, enhanced the motility defect, neurodegeneration and reduced longevity in our MJD models. Opposite to genetic inactivation, the overexpression of fkh-2 rescued the impaired motility, shortened-lifespan, and neurodegeneration phenotypes of mutant ATXN3 transgenics. We found that overexpression of FKH-2/FOXG1 in ATXN3 mutant worms is neuroprotective.
Using our transgenic ATXN3 C. elegans models and the screening of an RNAi library, we gained insights into the pathways contributing to neurodegeneration, and found that FKH-2/FOXG1 has neuroprotective activity. These findings may aid the development of novel therapeutic interventions for MJD.
Experimental and Clinical Strategies for Treating Spinocerebellar Ataxia Type 3
2018, Neuroscience
Spinocerebellar ataxia type 3 (SCA3), or Machado–Joseph disease (MJD), is an autosomal dominant neurodegenerative disorder caused by the expansion of a polyglutamine (polyQ) tract in the ataxin-3 protein. To date, there is no effective therapy available to prevent progression of this disease. However, clinical strategies for alleviating various symptoms are imperative to promote a better quality of life for SCA3/MJD patients. Furthermore, experimental therapeutic strategies, including gene silencing or mutant protein clearance, mutant polyQ protein modification, stabilizing the native protein conformation, rescue of cellular dysfunction and neuromodulation to slow the progression of SCA3/MJD, have been developed. In this study, based on the current knowledge, I detail the clinical and experimental therapeutic strategies for treating SCA3/MJD, paying particular attention to drug discovery.
Toward understanding Machado-Joseph disease
2012, Progress in Neurobiology
Citation Excerpt :
The properties described for ATXN3 in vitro may represent an overly simplistic view of how ATXN3 actually functions in cells when interacting with its multiple known partners and potential substrates. ATXN3 is widely expressed throughout peripheral and neuronal tissues in many different cell types (Paulson et al., 1997a; Schmidt et al., 1998; Trottier et al., 1998; Wang et al., 1997). A similar expression pattern is observed for ATXN3 orthologs in other species (Costa et al., 2004; Rodrigues et al., 2007; Schmitt et al., 1997).
Machado–Joseph disease (MJD), also known as spinocerebellar ataxia type 3 (SCA3), is the most common inherited spinocerebellar ataxia and one of many polyglutamine neurodegenerative diseases. In MJD, a CAG repeat expansion encodes an abnormally long polyglutamine (polyQ) tract in the disease protein, ATXN3. Here we review MJD, focusing primarily on the function and dysfunction of ATXN3 and on advances toward potential therapies. ATXN3 is a deubiquitinating enzyme (DUB) whose highly specialized properties suggest that it participates in ubiquitin-dependent proteostasis. By virtue of its interactions with VCP, various ubiquitin ligases and other ubiquitin-linked proteins, ATXN3 may help regulate the stability or activity of many proteins in diverse cellular pathways implicated in proteotoxic stress response, aging, and cell differentiation. Expansion of the polyQ tract in ATXN3 is thought to promote an altered conformation in the protein, leading to changes in interactions with native partners and to the formation of insoluble aggregates. The development of a wide range of cellular and animal models of MJD has been crucial to the emerging understanding of ATXN3 dysfunction upon polyQ expansion. Despite many advances, however, the principal molecular mechanisms by which mutant ATXN3 elicits neurotoxicity remain elusive. In a chronic degenerative disease like MJD, it is conceivable that mutant ATXN3 triggers multiple, interconnected pathogenic cascades that precipitate cellular dysfunction and eventual cell death. A better understanding of these complex molecular mechanisms will be important as scientists and clinicians begin to focus on developing effective therapies for this incurable, fatal disorder.
Machado-Joseph disease/spinocerebellar ataxia type 3
2012, Handbook of Clinical Neurology
Citation Excerpt :
Thus, understanding the disease protein in which the MJD expansion occurs is important to understanding the mechanism of neurodegeneration. The ATXN3 gene encodes ataxin-3 (Fig. 27.1), also known as ATXN3, a 42-kD protein that is widely expressed in the CNS and elsewhere (Nihiyama et al., 1996; Paulson et al., 1997a; Wang et al., 1997; Schmidt et al., 1998; Tait et al., 1998; Schmitt et al., 2003; Do Carmo Costa et al., 2004). This discrepancy between widespread expression of ataxin-3 and selective neuronal degeneration is reminiscent of the many neurodegenerative diseases in which selective tissue vulnerability cannot be explained by restricted disease protein expression.
Machado–Joseph disease (MJD), also known as spinocerebellar ataxia type 3 (SCA3), may be the most common dominantly inherited ataxia in the world. Here I will review historical, clinical, neuropathological, genetic, and pathogenic features of MJD, and finish with a brief discussion of present, and possible future, treatment for this currently incurable disorder. Like many other dominantly inherited ataxias, MJD/SCA3 shows remarkable clinical heterogeneity, reflecting the underlying genetic defect: an unstable CAG trinucleotide repeat that varies in size among affected persons. This pathogenic repeat in MJD/SCA3 encodes an expanded tract of the amino acid glutamine in the disease protein, which is known as ataxin-3. MJD/SCA3 is one of nine identified polyglutamine neurodegenerative diseases which share features of pathogenesis centered on protein misfolding and accumulation. The specific properties of MJD/SCA3 and its disease protein are discussed in light of what is known about the entire class of polyglutamine diseases.
Polyglutamine diseases: The special case of ataxin-3 and Machado-Joseph disease
2011, Progress in Neurobiology
Citation Excerpt :
Atx3 participation in the UPP may make it responsible for the regulation of the half-life of several different proteins, which in turn take part in diverse cell functions (do Carmo Costa et al., 2010; Evert et al., 2006a; Rodrigues et al., 2007, 2010). In addition to the ubiquitous distribution of atx3 among tissues, the protein seems to be widely, though heterogeneously, distributed within the cells themselves, being found in the cytoplasm (mitochondria included) and the nucleus, with varying degrees of predominance depending on the cell type (Macedo-Ribeiro et al., 2009; Paulson et al., 1997b; Pozzi et al., 2008; Reina et al., 2010; Tait et al., 1998; Trottier et al., 1998; Wang et al., 1997). In human brain cells, atx3 localizes mainly in the perikarya, though, depending on the analyzed cells, it was also detected on proximal processes, axons and nuclei.
Polyglutamine (polyQ) diseases are a group of nine neurodegenerative disorders caused by an unstable CAG expansion in the codifying region of their respective associated genes. However, each polyQ disease displays a different symptomatic and pathoanatomic profile and the proteins involved share no homology outside the polyQ tract. This suggests that the other regions of the proteins and the cellular functions they mediate are important in defining disease progression and specificity. Machado–Joseph disease (MJD), the most common form of spinocerebellar ataxia worldwide, is a progressive and ultimately fatal neurodegenerative disorder caused by polyQ expansion in ataxin-3 (atx3), a conserved and ubiquitous protein known to bind polyubiquitin chains and to function as a deubiquitinating enzyme. Atx3 has been linked to protein homeostasis maintenance, transcription, cytoskeleton regulation and myogenesis, but its precise biologic function remains a mystery, limiting the understanding of the mechanisms by which the mutated protein leads to the selective neuronal death profile observed in MJD patients. A number of recent evidence support the idea that the toxic entities behind neuronal demise may be either the dysfunctional expanded atx3 or the soluble amyloid-like oligomers formed by self-assembly of the aggregation-prone mutated protein. Expanded atx3 pathogenicity is likely the result of a series of events implicating both atx3 dysfunction and aggregation, possibly involving both full-length atx3 and polyQ-containing fragments that may act as seeds for protein aggregation. A deeper understanding of polyQ protein biology, the way the expansion alters their features, and the consequences of these changes for cell functioning and survival are sure to be of critical importance for developing future treatment of polyQ diseases.
Decreased protein synthesis of Hsp27 associated with cellular toxicity in a cell model of Machado-Joseph disease
2009, Neuroscience Letters
Machado–Joseph disease is an autosomal dominant spinocerebellar degeneration caused by the expansion of a polyglutamine tract within the gene product, ataxin-3. We have previously shown that increased oxidative stress and decreased expression of Hsp27 may be contributory factors to the disease progression. In this study, we utilized neuroblastoma SK-N-SH cells stably transfected with full-length expanded ataxin-3 to further investigate the mechanism(s) resulting in the decreased expression of Hsp27. Results from ³⁵S-methionine pulse-chase labeling and protein degradation assays revealed that decreased Hsp27 in mutant MJD cells is due to defects in protein synthesis. Our results further demonstrated that Hsp27 degradation is independent of the proteasome degradation pathway. In addition, we showed that overexpression of Hsp27 desensitizes mutant MJD cells to apoptotic stress. Taken together, these findings provide the first evidence that expanded ataxin-3 interferes with Hsp27 synthesis, which may contribute to the impairment of the cells’ ability to respond to stresses and trigger the progression of this late-onset disease.

View all citing articles on Scopus

^☆: G. Wang and K. Ide contributed equally to this work.

²: To whom correspondence should be addressed. Fax: 813-3813-2129. E-mail:[email protected].

View full text

Regular ArticleMachado–Joseph Disease Gene Product Identified in Lymphocytes and Brain☆

Abstract

Biochem. Biophys Res. Commun.

Mov. Disord.

Nature Genet.

Nature Genet.

Ann. Neurol.

Nature

Cell

Nature Genet.

Nature Genet.

Nature Genet.

Regular Article
Machado–Joseph Disease Gene Product Identified in Lymphocytes and Brain☆