The stress granule protein G3BP1 reduces the levels of different polyglutamine proteins and alleviates spinocerebellar ataxia associated deficits

Abstract Polyglutamine (polyQ) diseases are a group of 9 rare neurodegenerative disorders caused by an abnormal expansion of the CAG trinucleotide in the codifying regions of the respective disease-associated gene. The trinucleotide abnormal expansion leads to the translation of a protein containing an overexpanded tract of glutamines. PolyQ mutant proteins undergo a gain of toxic function disrupting normal cellular pathways leading to neuronal death and, consequently, leading to selective neurodegeneration of specific brain regions. Spinocerebellar ataxia (SCA) 2 and SCA3 (also known as Machado-Joseph disease) are two different polyQ diseases in which the ataxin-2 and ataxin-3 proteins, respectively, bear abnormally long polyQ tracts. Until now, there is no treatment for these fatal diseases or therapies that could delay the normal pathologic progression. Stress granules (SGs) are important structures formed in response to cellular stress, having an important role in mRNA triage. A core component of SGs is the RNA-binding protein (RBP) Ras GTPase-activating protein-binding protein 1 (G3BP1), which is also implicated in the SGs assembly. Furthermore, G3BP1 is known to have endoribonuclease activity and an important role in modulating RNA metabolism. In this study, we showed that G3BP1 is decreased in context of SCA2 and SCA3 disease. For that, we assessed whether restoring the expression levels of G3BP1 might positively impact the SCA2 and SCA3 pathology. We showed that gene delivery of G3BP1 in two distinct lentiviral mouse model of SCA2 and SCA3 was able to i) reduce the number of aggregates and ii) reduce the loss of neuronal marker associated with the mutant toxic proteins. Importantly, in a polyQ transgenic mouse model, lentiviral delivery of G3BP1 in the cerebellum was able to i) preserve the number of Purkinje cells, ii) reduce the number of HA-ataxin-3 and, importantly iii) improve the motor performance, balance and coordination. Additionally, we identify the nuclear transport nuclear transport factor 2-like (NTF2-like) domain and the ser149 phosphorylation site of G3BP1 as a key players in the reduction of mutant ataxin-2 and ataxin-3 levels and aggregation. Altogether these results showed that gene delivery of G3BP1 is able of mitigating the disease-associated phenotype in SCA2 and SCA3 disease, in three different disease mouse models. Therefore, this study suggests G3BP1 as a novel therapeutic target for SCA2 and SCA3 diseases.

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The RNA ‐binding protein and stress granule component ATAXIN ‐2 is expressed in mouse and human tissues associated with glaucoma pathogenesis

The Journal of Comparative Neurology ◽

10.1002/cne.25228 ◽

2021 ◽

Author(s):

Chad Sundberg ◽

Monika Lakk ◽

Sharan Paul ◽

K. P. Figueroa ◽

Daniel R. Scoles ◽

...

Keyword(s):

Rna Binding ◽

Binding Protein ◽

Rna Binding Protein ◽

Stress Granule ◽

Human Tissues ◽

Ataxin 2

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Constitutive Musashi1 expression impairs mouse postnatal development and intestinal homeostasis

Molecular Biology of the Cell ◽

10.1091/mbc.e20-03-0206 ◽

2021 ◽

Vol 32 (1) ◽

pp. 28-44

Author(s):

Thelma T. Chiremba ◽

Kristi L. Neufeld

Keyword(s):

Mouse Model ◽

Postnatal Development ◽

Rna Binding ◽

Binding Protein ◽

Rna Binding Protein ◽

Intestinal Homeostasis ◽

Developmental Defects ◽

Tissue Specific ◽

Specific Effects

We report the generation of a versatile mouse model that facilitates Cre-inducible and tissue-specific overexpression of RNA-binding protein Musashi1. Ubiquitous overexpression resulted in postnatal developmental defects including shortened intestines. Alterations in intestinal size and differentiation indicated region-specific effects of Musashi1.

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The RNA-binding protein ATX-2 regulates cytokinesis through PAR-5 and ZEN-4

Molecular Biology of the Cell ◽

10.1091/mbc.e16-04-0219 ◽

2016 ◽

Vol 27 (20) ◽

pp. 3052-3064 ◽

Cited By ~ 10

Author(s):

Megan M. Gnazzo ◽

Eva-Maria E. Uhlemann ◽

Alex R. Villarreal ◽

Masaki Shirayama ◽

Eddie G. Dominguez ◽

...

Keyword(s):

Cell Division ◽

Posttranscriptional Regulation ◽

Direct Evidence ◽

Rna Binding ◽

Binding Protein ◽

Rna Binding Protein ◽

Spindle Midzone ◽

Ataxin 2 ◽

Temporal And Spatial

The spindle midzone harbors both microtubules and proteins necessary for furrow formation and the completion of cytokinesis. However, the mechanisms that mediate the temporal and spatial recruitment of cell division factors to the spindle midzone and midbody remain unclear. Here we describe a mechanism governed by the conserved RNA-binding protein ATX-2/Ataxin-2, which targets and maintains ZEN-4 at the spindle midzone. ATX-2 does this by regulating the amount of PAR-5 at mitotic structures, particularly the spindle, centrosomes, and midbody. Preventing ATX-2 function leads to elevated levels of PAR-5, enhanced chromatin and centrosome localization of PAR-5–GFP, and ultimately a reduction of ZEN-4–GFP at the spindle midzone. Codepletion of ATX-2 and PAR-5 rescued the localization of ZEN-4 at the spindle midzone, indicating that ATX-2 mediates the localization of ZEN-4 upstream of PAR-5. We provide the first direct evidence that ATX-2 is necessary for cytokinesis and suggest a model in which ATX-2 facilitates the targeting of ZEN-4 to the spindle midzone by mediating the posttranscriptional regulation of PAR-5.

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Myofibrillar disruption and RNA-binding protein aggregation in a mouse model of limb-girdle muscular dystrophy 1D

Human Molecular Genetics ◽

10.1093/hmg/ddv363 ◽

2015 ◽

Vol 24 (23) ◽

pp. 6588-6602 ◽

Cited By ~ 17

Author(s):

Rocio Bengoechea ◽

Sara K. Pittman ◽

Elizabeth P. Tuck ◽

Heather L. True ◽

Conrad C. Weihl

Keyword(s):

Muscular Dystrophy ◽

Mouse Model ◽

Protein Aggregation ◽

Rna Binding ◽

Binding Protein ◽

Rna Binding Protein ◽

Limb Girdle Muscular Dystrophy

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Elevation of RNA-binding protein CUGBP1 is an early event in an inducible heart-specific mouse model of myotonic dystrophy

Journal of Clinical Investigation ◽

10.1172/jci32308 ◽

2007 ◽

Vol 117 (10) ◽

pp. 2802-2811 ◽

Cited By ~ 124

Author(s):

Guey-Shin Wang ◽

Debra L. Kearney ◽

Mariella De Biasi ◽

George Taffet ◽

Thomas A. Cooper

Keyword(s):

Mouse Model ◽

Myotonic Dystrophy ◽

Rna Binding ◽

Binding Protein ◽

Rna Binding Protein ◽

Early Event

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Direct evidence that Ataxin-2 is a translational activator mediating cytoplasmic polyadenylation

Journal of Biological Chemistry ◽

10.1074/jbc.ra120.013835 ◽

2020 ◽

Vol 295 (47) ◽

pp. 15810-15825

Author(s):

Hiroto Inagaki ◽

Nao Hosoda ◽

Hitomi Tsuiji ◽

Shin-ichi Hoshino

Keyword(s):

Direct Evidence ◽

Rna Binding ◽

Profile Analysis ◽

Binding Protein ◽

Spinocerebellar Ataxia Type ◽

Causative Role ◽

Cytoplasmic Polyadenylation ◽

Intrinsically Disordered ◽

Target Mrnas ◽

Ataxin 2

The RNA-binding protein Ataxin-2 binds to and stabilizes a number of mRNA sequences, including that of the transactive response DNA-binding protein of 43 kDa (TDP-43). Ataxin-2 is additionally involved in several processes requiring translation, such as germline formation, long-term habituation, and circadian rhythm formation. However, it has yet to be unambiguously demonstrated that Ataxin-2 is actually involved in activating the translation of its target mRNAs. Here we provide direct evidence from a polysome profile analysis showing that Ataxin-2 enhances translation of target mRNAs. Our recently established method for transcriptional pulse-chase analysis under conditions of suppressing deadenylation revealed that Ataxin-2 promotes post-transcriptional polyadenylation of the target mRNAs. Furthermore, Ataxin-2 binds to a poly(A)-binding protein PABPC1 and a noncanonical poly(A) polymerase PAPD4 via its intrinsically disordered region (amino acids 906–1095) to recruit PAPD4 to the targets. Post-transcriptional polyadenylation by Ataxin-2 explains not only how it activates translation but also how it stabilizes target mRNAs, including TDP-43 mRNA. Ataxin-2 is known to be a potent modifier of TDP-43 proteinopathies and to play a causative role in the neurodegenerative disease spinocerebellar ataxia type 2, so these findings suggest that Ataxin-2–induced cytoplasmic polyadenylation and activation of translation might impact neurodegeneration (i.e. TDP-43 proteinopathies), and this process could be a therapeutic target for Ataxin-2–related neurodegenerative disorders.

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Autophagy in Spinocerebellar ataxia type 2, a dysregulated pathway, and a target for therapy

Cell Death and Disease ◽

10.1038/s41419-021-04404-1 ◽

2021 ◽

Vol 12 (12) ◽

Author(s):

Adriana Marcelo ◽

Inês T. Afonso ◽

Ricardo Afonso-Reis ◽

David V. C. Brito ◽

Rafael G. Costa ◽

...

Keyword(s):

Spinocerebellar Ataxia ◽

Neurodegenerative Disorder ◽

Clinical Manifestations ◽

Brain Regions ◽

Spinocerebellar Ataxia Type ◽

Spinocerebellar Ataxia Type 2 ◽

Neuronal Marker ◽

Severe Motor ◽

Ataxin 2

AbstractSpinocerebellar ataxia type 2 (SCA2) is an incurable and genetic neurodegenerative disorder. The disease is characterized by progressive degeneration of several brain regions, resulting in severe motor and non-motor clinical manifestations. The mutation causing SCA2 disease is an abnormal expansion of CAG trinucleotide repeats in the ATXN2 gene, leading to a toxic expanded polyglutamine segment in the translated ataxin-2 protein. While the genetic cause is well established, the exact mechanisms behind neuronal death induced by mutant ataxin-2 are not yet completely understood. Thus, the goal of this study is to investigate the role of autophagy in SCA2 pathogenesis and investigate its suitability as a target for therapeutic intervention. For that, we developed and characterized a new striatal lentiviral mouse model that resembled several neuropathological hallmarks observed in SCA2 disease, including formation of aggregates, neuronal marker loss, cell death and neuroinflammation. In this new model, we analyzed autophagic markers, which were also analyzed in a SCA2 cellular model and in human post-mortem brain samples. Our results showed altered levels of SQSTM1 and LC3B in cells and tissues expressing mutant ataxin-2. Moreover, an abnormal accumulation of these markers was detected in SCA2 patients’ striatum and cerebellum. Importantly, the molecular activation of autophagy, using the compound cordycepin, mitigated the phenotypic alterations observed in disease models. Overall, our study suggests an important role for autophagy in the context of SCA2 pathology, proposing that targeting this pathway could be a potential target to treat SCA2 patients.

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Withaferin-A Treatment Alleviates TAR DNA-Binding Protein-43 Pathology and Improves Cognitive Function in a Mouse Model of FTLD

Neurotherapeutics ◽

10.1007/s13311-020-00952-0 ◽

2020 ◽

Author(s):

Sunny Kumar ◽

Daniel Phaneuf ◽

Jean-Pierre Julien

Keyword(s):

Cognitive Function ◽

Mouse Model ◽

Neurodegenerative Diseases ◽

Withania Somnifera ◽

Rna Binding ◽

Binding Protein ◽

Withaferin A ◽

Age Related ◽

The Brain ◽

Herbal Plant

AbstractWithaferin-A, an active withanolide derived from the medicinal herbal plant Withania somnifera induces autophagy, reduces TDP-43 proteinopathy, and improves cognitive function in transgenic mice expressing mutant TDP-43 modelling FTLD. TDP-43 is a nuclear DNA/RNA-binding protein with cellular functions in RNA transcription and splicing. Abnormal cytoplasmic aggregates of TDP-43 occur in several neurodegenerative diseases including amyotrophic lateral sclerosis (ALS), frontotemporal lobar degeneration (FTLD), and limbic-predominant age-related TDP-43 encephalopathy (LATE). To date, no effective treatment is available for TDP-43 proteinopathies. Here, we tested the effects of withaferin-A (WFA), an active withanolide extracted from the medicinal herbal plant Withania somnifera, in a transgenic mouse model of FTLD expressing a genomic fragment encoding mutant TDP-43G348C. WFA treatment ameliorated the cognitive performance of the TDP-43G348C mice, and it reduced NF-κB activity and neuroinflammation in the brain. WFA alleviated TDP-43 pathology while it boosted the levels of the autophagic marker LC3BII in the brain. These data suggest that WFA and perhaps other autophagy inducers should be considered as potential therapy for neurodegenerative diseases with TDP-43 pathology.

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