101
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Modulation of Molecular Chaperones in Huntington’s Disease and Other Polyglutamine Disorders. Mol Neurobiol 2016; 54:5829-5854. [DOI: 10.1007/s12035-016-0120-z] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/19/2016] [Accepted: 09/12/2016] [Indexed: 12/20/2022]
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102
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Weingarten-Gabbay S, Segal E. Toward a systematic understanding of translational regulatory elements in human and viruses. RNA Biol 2016; 13:927-933. [PMID: 27442807 DOI: 10.1080/15476286.2016.1212802] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022] Open
Abstract
Translational regulation is a critical step in the production of proteins from genomic material in both human and viruses. However, unlike other steps of the central dogma, such as transcriptional regulation, little is known about the cis-regulatory elements involved. In a recent study we devised a high-throughput bicistronic reporter assay for the discovery and the characterization of thousands of novel Internal Ribosome Entry Sites (IRESs) in human and hundreds of viral genomes. Our results provide insights into the landscape of IRES elements in human and viral transcripts and the cis-regulatory sequences underlying their activity. Here, we discuss these results as well as emerging insights from other studies, providing new views about translational regulation in human and viruses. In addition, we highlight recent high-throughput technologies in the field and discuss how combining insights from high- and low-throughput approaches can illuminate yet uncovered mechanisms of translational regulation.
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Affiliation(s)
- Shira Weingarten-Gabbay
- a Department of Computer Science and Applied Mathematics , Weizmann Institute of Science , Rehovot , Israel.,b Department of Molecular Cell Biology , Weizmann Institute of Science , Rehovot , Israel
| | - Eran Segal
- a Department of Computer Science and Applied Mathematics , Weizmann Institute of Science , Rehovot , Israel.,b Department of Molecular Cell Biology , Weizmann Institute of Science , Rehovot , Israel
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103
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Jayabal S, Chang HHV, Cullen KE, Watt AJ. 4-aminopyridine reverses ataxia and cerebellar firing deficiency in a mouse model of spinocerebellar ataxia type 6. Sci Rep 2016; 6:29489. [PMID: 27381005 PMCID: PMC4933933 DOI: 10.1038/srep29489] [Citation(s) in RCA: 64] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/24/2016] [Accepted: 06/17/2016] [Indexed: 12/02/2022] Open
Abstract
Spinocerebellar ataxia type 6 (SCA6) is a devastating midlife-onset autosomal dominant motor control disease with no known treatment. Using a hyper-expanded polyglutamine (84Q) knock-in mouse, we found that cerebellar Purkinje cell firing precision was degraded in heterozygous (SCA684Q/+) mice at 19 months when motor deficits are observed. Similar alterations in firing precision and motor control were observed at disease onset at 7 months in homozygous (SCA684Q/84Q) mice, as well as a reduction in firing rate. We further found that chronic administration of the FDA-approved drug 4-aminopyridine (4-AP), which targets potassium channels, alleviated motor coordination deficits and restored cerebellar Purkinje cell firing precision to wildtype (WT) levels in SCA684Q/84Q mice both in acute slices and in vivo. These results provide a novel therapeutic approach for treating ataxic symptoms associated with SCA6.
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Affiliation(s)
- Sriram Jayabal
- Department of Biology, McGill University, Montreal, H3G 0B1, Canada.,Integrated Program in Neuroscience, McGill University, Montreal, H3G 0B1, Canada
| | | | - Kathleen E Cullen
- Department of Physiology, McGill University, Montreal, H3G 1Y6, Canada
| | - Alanna J Watt
- Department of Biology, McGill University, Montreal, H3G 0B1, Canada
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104
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Mark MD, Schwitalla JC, Groemmke M, Herlitze S. Keeping Our Calcium in Balance to Maintain Our Balance. Biochem Biophys Res Commun 2016; 483:1040-1050. [PMID: 27392710 DOI: 10.1016/j.bbrc.2016.07.020] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/30/2016] [Accepted: 07/04/2016] [Indexed: 01/13/2023]
Abstract
Calcium is a key signaling molecule and ion involved in a variety of diverse processes in our central nervous system (CNS) which include gene expression, synaptic transmission and plasticity, neuronal excitability and cell maintenance. Proper control of calcium signaling is not only vital for neuronal physiology but also cell survival. Mutations in fundamental channels, transporters and second messenger proteins involved in orchestrating the balance of our calcium homeostasis can lead to severe neurodegenerative disorders, such as Spinocerebellar (SCA) and Episodic (EA) ataxias. Hereditary ataxias make up a remarkably diverse group of neurological disorders clinically characterized by gait ataxia, nystagmus, dysarthria, trunk and limb ataxia and often atrophy of the cerebellum. The largest family of hereditary ataxias is SCAs which consists of a growing family of 42 members. A relatively smaller family of 8 members compose the EAs. The gene mutations responsible for half of the EA members and over 35 of the SCA subtypes have been identified, and several have been found to be responsible for cerebellar atrophy, abnormal intracellular calcium levels, dysregulation of Purkinje cell pacemaking, altered cerebellar synaptic transmission and/or ataxia in mouse models. Although the genetic diversity and affected cellular pathways of hereditary ataxias are broad, one common theme amongst these genes is their effects on maintaining calcium balance in primarily the cerebellum. There is emerging evidence that the pathogenesis of hereditary ataxias may be caused by imbalances in intracellular calcium due to genetic mutations in calcium-mediating proteins. In this review we will discuss the current evidence supporting the role of deranged calcium as the culprit to neurodegenerative diseases with a primary focus on SCAs and EAs.
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Affiliation(s)
- Melanie D Mark
- Department of Zoology and Neurobiology, ND7/31, Ruhr University Bochum, Universitätsstr. 150, D-44780 Bochum, Germany.
| | - Jan Claudius Schwitalla
- Department of Zoology and Neurobiology, ND7/31, Ruhr University Bochum, Universitätsstr. 150, D-44780 Bochum, Germany
| | - Michelle Groemmke
- Department of Zoology and Neurobiology, ND7/31, Ruhr University Bochum, Universitätsstr. 150, D-44780 Bochum, Germany
| | - Stefan Herlitze
- Department of Zoology and Neurobiology, ND7/31, Ruhr University Bochum, Universitätsstr. 150, D-44780 Bochum, Germany
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105
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Designing synthetic RNAs to determine the relevance of structural motifs in picornavirus IRES elements. Sci Rep 2016; 6:24243. [PMID: 27053355 PMCID: PMC4823658 DOI: 10.1038/srep24243] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/17/2015] [Accepted: 03/23/2016] [Indexed: 12/22/2022] Open
Abstract
The function of Internal Ribosome Entry Site (IRES) elements is intimately linked to their RNA structure. Viral IRES elements are organized in modular domains consisting of one or more stem-loops that harbor conserved RNA motifs critical for internal initiation of translation. A conserved motif is the pyrimidine-tract located upstream of the functional initiation codon in type I and II picornavirus IRES. By computationally designing synthetic RNAs to fold into a structure that sequesters the polypyrimidine tract in a hairpin, we establish a correlation between predicted inaccessibility of the pyrimidine tract and IRES activity, as determined in both in vitro and in vivo systems. Our data supports the hypothesis that structural sequestration of the pyrimidine-tract within a stable hairpin inactivates IRES activity, since the stronger the stability of the hairpin the higher the inhibition of protein synthesis. Destabilization of the stem-loop immediately upstream of the pyrimidine-tract also decreases IRES activity. Our work introduces a hybrid computational/experimental method to determine the importance of structural motifs for biological function. Specifically, we show the feasibility of using the software RNAiFold to design synthetic RNAs with particular sequence and structural motifs that permit subsequent experimental determination of the importance of such motifs for biological function.
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106
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Weingarten-Gabbay S, Elias-Kirma S, Nir R, Gritsenko AA, Stern-Ginossar N, Yakhini Z, Weinberger A, Segal E. Comparative genetics. Systematic discovery of cap-independent translation sequences in human and viral genomes. Science 2016; 351:351/6270/aad4939. [PMID: 26816383 DOI: 10.1126/science.aad4939] [Citation(s) in RCA: 211] [Impact Index Per Article: 26.4] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/20/2015] [Accepted: 11/11/2015] [Indexed: 12/12/2022]
Abstract
To investigate gene specificity at the level of translation in both the human genome and viruses, we devised a high-throughput bicistronic assay to quantify cap-independent translation. We uncovered thousands of novel cap-independent translation sequences, and we provide insights on the landscape of translational regulation in both humans and viruses. We find extensive translational elements in the 3' untranslated region of human transcripts and the polyprotein region of uncapped RNA viruses. Through the characterization of regulatory elements underlying cap-independent translation activity, we identify potential mechanisms of secondary structure, short sequence motif, and base pairing with the 18S ribosomal RNA (rRNA). Furthermore, we systematically map the 18S rRNA regions for which reverse complementarity enhances translation. Thus, we make available insights into the mechanisms of translational control in humans and viruses.
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Affiliation(s)
- Shira Weingarten-Gabbay
- Department of Computer Science and Applied Mathematics, Weizmann Institute of Science, Rehovot 76100, Israel. Department of Molecular Cell Biology, Weizmann Institute of Science, Rehovot 76100, Israel
| | - Shani Elias-Kirma
- Department of Computer Science and Applied Mathematics, Weizmann Institute of Science, Rehovot 76100, Israel. Department of Molecular Cell Biology, Weizmann Institute of Science, Rehovot 76100, Israel
| | - Ronit Nir
- Department of Computer Science and Applied Mathematics, Weizmann Institute of Science, Rehovot 76100, Israel. Department of Molecular Cell Biology, Weizmann Institute of Science, Rehovot 76100, Israel
| | - Alexey A Gritsenko
- The Delft Bioinformatics Laboratory, Department of Intelligent Systems, Delft University of Technology, Delft, Netherlands. Platform Green Synthetic Biology, Delft, Netherlands. Kluyver Centre for Genomics of Industrial Fermentation, Delft, Netherlands
| | - Noam Stern-Ginossar
- Department of Molecular Genetics, Weizmann Institute of Science, Rehovot 76100, Israel
| | - Zohar Yakhini
- Department of Computer Science, Technion, Haifa, Israel. Agilent Laboratories, Tel-Aviv, Israel
| | - Adina Weinberger
- Department of Computer Science and Applied Mathematics, Weizmann Institute of Science, Rehovot 76100, Israel. Department of Molecular Cell Biology, Weizmann Institute of Science, Rehovot 76100, Israel
| | - Eran Segal
- Department of Computer Science and Applied Mathematics, Weizmann Institute of Science, Rehovot 76100, Israel. Department of Molecular Cell Biology, Weizmann Institute of Science, Rehovot 76100, Israel.
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107
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Lozano G, Fernandez N, Martinez-Salas E. Modeling Three-Dimensional Structural Motifs of Viral IRES. J Mol Biol 2016; 428:767-776. [PMID: 26778619 DOI: 10.1016/j.jmb.2016.01.005] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/10/2015] [Revised: 01/08/2016] [Accepted: 01/08/2016] [Indexed: 01/23/2023]
Abstract
RNA virus genomes are reservoirs of a wide diversity of RNA structural elements. In particular, specific regions of the viral genome have evolved to adopt specialized three-dimensional (3D) structures, which can act in concert with host factors and/or viral proteins to recruit the translation machinery on viral RNA using a mechanism that is independent on the 5' end. This strategy relies on cis-acting RNA sequences designated as internal ribosome entry site (IRES) elements. IRES elements that are found in the genome of different groups of RNA viruses perform the same function despite differing in primary sequence and secondary RNA structure and host factor requirement to recruit the translation machinery internally. Evolutionarily conserved motifs tend to preserve sequences in each group of RNA viruses impacting on RNA structure and RNA-protein interactions important for IRES function. However, due to the lack of sequence homology among genetically distant IRES elements, accurate modeling of 3D IRES structure is currently a challenging task. In addition, as a universal RNA motif unique to IRES elements has not been found, a better understanding of viral IRES structural motifs could greatly assist in the detection of IRES-like motifs hidden in genome sequences. The focus of this review is to describe recent advances in modeling viral IRES tertiary structural motifs and also novel approaches to detect sequences potentially folding as IRES-like motifs.
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Affiliation(s)
- Gloria Lozano
- Centro de Biología Molecular Severo Ochoa, Consejo Superior de Investigaciones Científicas Universidad Autónoma de Madrid, Nicolas Cabrera 1, 28049 Madrid, Spain
| | - Noemi Fernandez
- Centro de Biología Molecular Severo Ochoa, Consejo Superior de Investigaciones Científicas Universidad Autónoma de Madrid, Nicolas Cabrera 1, 28049 Madrid, Spain
| | - Encarnacion Martinez-Salas
- Centro de Biología Molecular Severo Ochoa, Consejo Superior de Investigaciones Científicas Universidad Autónoma de Madrid, Nicolas Cabrera 1, 28049 Madrid, Spain.
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108
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Wang J, Sun K, Shen Y, Xu Y, Xie J, Huang R, Zhang Y, Xu C, Zhang X, Wang R, Lin Y. DNA methylation is critical for tooth agenesis: implications for sporadic non-syndromic anodontia and hypodontia. Sci Rep 2016; 6:19162. [PMID: 26759063 PMCID: PMC4725352 DOI: 10.1038/srep19162] [Citation(s) in RCA: 28] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/01/2015] [Accepted: 12/02/2015] [Indexed: 02/05/2023] Open
Abstract
Hypodontia is caused by interactions among genetic, epigenetic, and environmental factors during tooth development, but the actual mechanism is unknown. DNA methylation now appears to play a significant role in abnormal developments, flawed phenotypes, and acquired diseases. Methylated DNA immunoprecipitation (MeDIP) has been developed as a new method of scanning large-scale DNA-methylation profiles within particular regions or in the entire genome. Here, we performed a genome-wide scan of paired DNA samples obtained from 4 patients lacking two mandibular incisors and 4 healthy controls with normal dentition. We scanned another female with non-syndromic anodontia and her younger brother with the same gene mutations of the PAX9,MSX1,AXIN2 and EDA, but without developmental abnormalities in the dentition. Results showed significant differences in the methylation level of the whole genome between the hypodontia and the normal groups. Nine genes were spotted, some of which have not been associated with dental development; these genes were related mainly to the development of cartilage, bone, teeth, and neural transduction, which implied a potential gene cascade network in hypodontia at the methylation level. This pilot study reveals the critical role of DNA methylation in hypodontia and might provide insights into developmental biology and the pathobiology of acquired diseases.
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Affiliation(s)
- Jing Wang
- Department of Stomatology, Shanghai Tenth People's Hospital, Tongji University School of Medicine, No.301, Middle Yanchang Road, Shanghai 200072, P.R. China
| | - Ke Sun
- State Key Laboratory of Oral Diseases, West China Hospital of Stomatology, Sichuan University, No.14., 3rd Sec, Ren Min Nan Road, Chengdu 610041, P.R. China
| | - Yun Shen
- Department of Stomatology, Shanghai Tenth People's Hospital, Tongji University School of Medicine, No.301, Middle Yanchang Road, Shanghai 200072, P.R. China
| | - Yuanzhi Xu
- Department of Stomatology, Shanghai Tenth People's Hospital, Tongji University School of Medicine, No.301, Middle Yanchang Road, Shanghai 200072, P.R. China
| | - Jing Xie
- State Key Laboratory of Oral Diseases, West China Hospital of Stomatology, Sichuan University, No.14., 3rd Sec, Ren Min Nan Road, Chengdu 610041, P.R. China
| | - Renhuan Huang
- State Key Laboratory of Oral Diseases, West China Hospital of Stomatology, Sichuan University, No.14., 3rd Sec, Ren Min Nan Road, Chengdu 610041, P.R. China
| | - Yiming Zhang
- Department of Stomatology, Shanghai Tenth People's Hospital, Tongji University School of Medicine, No.301, Middle Yanchang Road, Shanghai 200072, P.R. China
| | - Chenyuan Xu
- Department of Stomatology, Shanghai Tenth People's Hospital, Tongji University School of Medicine, No.301, Middle Yanchang Road, Shanghai 200072, P.R. China
| | - Xu Zhang
- Department of Stomatology, Shanghai Tenth People's Hospital, Tongji University School of Medicine, No.301, Middle Yanchang Road, Shanghai 200072, P.R. China
| | - Raorao Wang
- Department of Stomatology, Shanghai Tenth People's Hospital, Tongji University School of Medicine, No.301, Middle Yanchang Road, Shanghai 200072, P.R. China
| | - Yunfeng Lin
- State Key Laboratory of Oral Diseases, West China Hospital of Stomatology, Sichuan University, No.14., 3rd Sec, Ren Min Nan Road, Chengdu 610041, P.R. China
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109
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Rapid Onset of Motor Deficits in a Mouse Model of Spinocerebellar Ataxia Type 6 Precedes Late Cerebellar Degeneration. eNeuro 2015; 2:eN-CFN-0094-15. [PMID: 26730403 PMCID: PMC4697081 DOI: 10.1523/eneuro.0094-15.2015] [Citation(s) in RCA: 28] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/17/2015] [Revised: 11/04/2015] [Accepted: 11/11/2015] [Indexed: 01/08/2023] Open
Abstract
Spinocerebellar ataxia type 6 (SCA6) is an autosomal-dominant cerebellar ataxia that has been associated with loss of cerebellar Purkinje cells. Disease onset is typically at midlife, although it can vary widely from late teens to old age in SCA6 patients. Our study focused on an SCA6 knock-in mouse model with a hyper-expanded (84X) CAG repeat expansion that displays midlife-onset motor deficits at ∼7 months old, reminiscent of midlife-onset symptoms in SCA6 patients, although a detailed phenotypic analysis of these mice has not yet been reported. Here, we characterize the onset of motor deficits in SCA684Q mice using a battery of behavioral assays to test for impairments in motor coordination, balance, and gait. We found that these mice performed normally on these assays up to and including at 6 months, but motor impairment was detected at 7 months with all motor coordination assays used, suggesting that motor deficits emerge rapidly during a narrow age window in SCA684Q mice. In contrast to what is seen in SCA6 patients, the decrease in motor coordination was observed without alterations in gait. No loss of cerebellar Purkinje cells or striatal neurons were observed at 7 months, the age at which motor deficits were first detected, but significant Purkinje cell loss was observed in 2-year-old SCA684Q mice, arguing that Purkinje cell death does not significantly contribute to the early stages of SCA6.
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110
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Li J, You Y, Yue W, Jia M, Yu H, Lu T, Wu Z, Ruan Y, Wang L, Zhang D. Genetic Evidence for Possible Involvement of the Calcium Channel Gene CACNA1A in Autism Pathogenesis in Chinese Han Population. PLoS One 2015; 10:e0142887. [PMID: 26566276 PMCID: PMC4643966 DOI: 10.1371/journal.pone.0142887] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/05/2015] [Accepted: 10/28/2015] [Indexed: 02/06/2023] Open
Abstract
Autism spectrum disorders (ASD) are a group of neurodevelopmental disorders. Recent studies suggested that calcium channel genes might be involved in the genetic etiology of ASD. CACNA1A, encoding an alpha-1 subunit of voltage-gated calcium channel, has been reported to play an important role in neural development. Previous study detected that a single nucleotide polymorphism (SNP) in CACNA1A confers risk to ASD in Central European population. However, the genetic relationship between autism and CACNA1A in Chinese Han population remains unclear. To explore the association of CACNA1A with autism, we performed a family-based association study. First, we carried out a family-based association test between twelve tagged SNPs and autism in 239 trios. To further confirm the association, the sample size was expanded to 553 trios by recruiting 314 additional trios. In a total of 553 trios, we identified association of rs7249246 and rs12609735 with autism though this would not survive after Bonferroni correction. Our findings suggest that CACNA1A might play a role in the etiology of autism.
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Affiliation(s)
- Jun Li
- Institute of Mental Health, The Sixth Hospital, Peking University, Beijing, China
- Key Laboratory of Mental Health, Ministry of Health & National Clinical Research Center for Mental Disorders (Peking University), Beijing, China
| | - Yang You
- Institute of Mental Health, The Sixth Hospital, Peking University, Beijing, China
- Key Laboratory of Mental Health, Ministry of Health & National Clinical Research Center for Mental Disorders (Peking University), Beijing, China
| | - Weihua Yue
- Institute of Mental Health, The Sixth Hospital, Peking University, Beijing, China
- Key Laboratory of Mental Health, Ministry of Health & National Clinical Research Center for Mental Disorders (Peking University), Beijing, China
| | - Meixiang Jia
- Institute of Mental Health, The Sixth Hospital, Peking University, Beijing, China
- Key Laboratory of Mental Health, Ministry of Health & National Clinical Research Center for Mental Disorders (Peking University), Beijing, China
| | - Hao Yu
- Institute of Mental Health, The Sixth Hospital, Peking University, Beijing, China
- Key Laboratory of Mental Health, Ministry of Health & National Clinical Research Center for Mental Disorders (Peking University), Beijing, China
- Peking-Tsinghua Center for Life Sciences, Peking University, Beijing, P. R. China
| | - Tianlan Lu
- Institute of Mental Health, The Sixth Hospital, Peking University, Beijing, China
- Key Laboratory of Mental Health, Ministry of Health & National Clinical Research Center for Mental Disorders (Peking University), Beijing, China
| | - Zhiliu Wu
- Institute of Mental Health, The Sixth Hospital, Peking University, Beijing, China
- Key Laboratory of Mental Health, Ministry of Health & National Clinical Research Center for Mental Disorders (Peking University), Beijing, China
| | - Yanyan Ruan
- Institute of Mental Health, The Sixth Hospital, Peking University, Beijing, China
- Key Laboratory of Mental Health, Ministry of Health & National Clinical Research Center for Mental Disorders (Peking University), Beijing, China
| | - Lifang Wang
- Institute of Mental Health, The Sixth Hospital, Peking University, Beijing, China
- Key Laboratory of Mental Health, Ministry of Health & National Clinical Research Center for Mental Disorders (Peking University), Beijing, China
- * E-mail: (DZ); (LFW)
| | - Dai Zhang
- Institute of Mental Health, The Sixth Hospital, Peking University, Beijing, China
- Key Laboratory of Mental Health, Ministry of Health & National Clinical Research Center for Mental Disorders (Peking University), Beijing, China
- Peking-Tsinghua Center for Life Sciences, Peking University, Beijing, P. R. China
- PKU-IDG/McGovern Institute for Brain Research, Peking University, Beijing, P. R. China
- * E-mail: (DZ); (LFW)
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111
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Aikawa T, Mogushi K, Iijima-Tsutsui K, Ishikawa K, Sakurai M, Tanaka H, Mizusawa H, Watase K. Loss of MyD88 alters neuroinflammatory response and attenuates early Purkinje cell loss in a spinocerebellar ataxia type 6 mouse model. Hum Mol Genet 2015; 24:4780-91. [PMID: 26034136 PMCID: PMC4527484 DOI: 10.1093/hmg/ddv202] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/08/2015] [Accepted: 05/26/2015] [Indexed: 11/14/2022] Open
Abstract
Spinocerebellar ataxia type 6 (SCA6) is dominantly inherited neurodegenerative disease, caused by an expansion of CAG repeat encoding a polyglutamine (PolyQ) tract in the Cav2.1 voltage-gated calcium channel. Its key pathological features include selective degeneration of the cerebellar Purkinje cells (PCs), a common target for PolyQ-induced toxicity in various SCAs. Mutant Cav2.1 confers toxicity primarily through a toxic gain-of-function mechanism; however, its molecular basis remains elusive. Here, we studied the cerebellar gene expression patterns of young Sca6-MPI(118Q/118Q) knockin (KI) mice, which expressed mutant Cav2.1 from an endogenous locus and recapitulated many phenotypic features of human SCA6. Transcriptional signatures in the MPI(118Q/118Q) mice were distinct from those in the Sca1(154Q/2Q) mice, a faithful SCA1 KI mouse model. Temporal expression profiles of the candidate genes revealed that the up-regulation of genes associated with microglial activation was initiated before PC degeneration and was augmented as the disease progressed. Histological analysis of the MPI(118Q/118Q) cerebellum showed the predominance of M1-like pro-inflammatory microglia and it was concomitant with elevated expression levels of tumor necrosis factor, interleukin-6, Toll-like receptor (TLR) 2 and 7. Genetic ablation of MyD88, a major adaptor protein conveying TLR signaling, altered expression patterns of M1/M2 microglial phenotypic markers in the MPI(118Q/118Q) cerebellum. More importantly, it ameliorated PC loss and partially rescued motor impairments in the early disease phase. These results suggest that early neuroinflammatory response may play an important role in the pathogenesis of SCA6 and its modulation could pave the way for slowing the disease progression during the early stage of the disease.
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Affiliation(s)
- Tomonori Aikawa
- Center for Brain Integration Research, Core Research for Evolutional Science and Technology (CREST) of the Japan Science and Technology (JST), Tokyo 102-8666, Japan
| | - Kaoru Mogushi
- Department of Bioinformatics, Medical Research Institute, Core Research for Evolutional Science and Technology (CREST) of the Japan Science and Technology (JST), Tokyo 102-8666, Japan, Center for Genomic and Regenerative Medicine, Juntendo University, Tokyo 113-0033, Japan
| | - Kumiko Iijima-Tsutsui
- Department of Bioinformatics, Medical Research Institute, Core Research for Evolutional Science and Technology (CREST) of the Japan Science and Technology (JST), Tokyo 102-8666, Japan, Department of Social Services and Healthcare Management, International University of Health and Welfare, Tochigi 324-8501, Japan and
| | - Kinya Ishikawa
- Department of Neurology and Neurogical Science, Tokyo Medical and Dental University, Tokyo 113-8510, Japan, Core Research for Evolutional Science and Technology (CREST) of the Japan Science and Technology (JST), Tokyo 102-8666, Japan
| | | | - Hiroshi Tanaka
- Department of Bioinformatics, Medical Research Institute, Core Research for Evolutional Science and Technology (CREST) of the Japan Science and Technology (JST), Tokyo 102-8666, Japan
| | - Hidehiro Mizusawa
- Center for Brain Integration Research, Department of Neurology and Neurogical Science, Tokyo Medical and Dental University, Tokyo 113-8510, Japan, Core Research for Evolutional Science and Technology (CREST) of the Japan Science and Technology (JST), Tokyo 102-8666, Japan, National Center Hospital, National Center of Neurology and Psychiatry, Tokyo 187-8551, Japan
| | - Kei Watase
- Center for Brain Integration Research, Core Research for Evolutional Science and Technology (CREST) of the Japan Science and Technology (JST), Tokyo 102-8666, Japan,
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112
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Spinocerebellar ataxia type 6 protein aggregates cause deficits in motor learning and cerebellar plasticity. J Neurosci 2015; 35:8882-95. [PMID: 26063920 DOI: 10.1523/jneurosci.0891-15.2015] [Citation(s) in RCA: 48] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
Spinocerebellar ataxia type 6 (SCA6) is linked to poly-glutamine (polyQ) within the C terminus (CT) of the pore-forming subunits of P/Q-type Ca(2+) channels (Cav2.1) and is characterized by CT protein aggregates found in cerebellar Purkinje cells (PCs). One hypothesis regarding SCA6 disease is that a CT fragment of the Cav2.1 channel, which is detected specifically in cytosolic and nuclear fractions in SCA6 patients, is associated with the SCA6 pathogenesis. To test this hypothesis, we expressed P/Q-type channel protein fragments from two different human CT splice variants, as predicted from SCA6 patients, in PCs of mice using viral and transgenic approaches. These splice variants represent a short (CT-short without polyQs) and a long (CT-long with 27 polyQs) CT fragment. Our results show that the different splice variants of the CTs differentially distribute within PCs, i.e., the short CTs reveal predominantly nuclear inclusions, whereas the long CTs prominently reveal both nuclear and cytoplasmic aggregates. Postnatal expression of CTs in PCs in mice reveals that only CT-long causes SCA6-like symptoms, i.e., deficits in eyeblink conditioning (EBC), ataxia, and PC degeneration. The physiological phenotypes associated specifically with the long CT fragment can be explained by an impairment of LTD and LTP at the parallel fiber-to-PC synapse and alteration in spontaneous PC activity. Thus, our results suggest that the polyQ carrying the CT fragment of the P/Q-type channel is sufficient to cause SCA6 pathogenesis in mice and identifies EBC as a new diagnostic strategy to evaluate Ca(2+) channel-mediated human diseases.
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113
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Welham A, Barth B, Moss J, Penhallow J, Sheth K, Wilde L, Wynn S, Oliver C. Behavioral characteristics associated with 19p13.2 microdeletions. Am J Med Genet A 2015; 167A:2334-43. [PMID: 26189583 DOI: 10.1002/ajmg.a.37180] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/10/2014] [Accepted: 05/03/2015] [Indexed: 01/16/2023]
Abstract
A small number of recent papers have described individuals with intellectual disabilities and microdeletions in chromosome band 19p13.2. However, little is known about the behavioral characteristics of individuals with microdeletions in this area. The current study examines behavioral characteristics of a series of 10 participants ranging in age from 2 to 20 years with 19p13.2 microdeletions. Parents/caregivers completed a series of established behavioral measures which have aided the elucidation of the behavioral phenotypes of a number of genetic neurodevelopmental syndromes. All but the youngest two participants (aged 2 and 3 years) were verbal, ambulant, and classified as "partly able" or "able" with regard to self-help skills. Six of eight participants for whom a screening measure for autism spectrum disorders (ASD) could be deployed met criteria for an ASD. Six of the 10 participants had displayed self-injurious behavior in the month prior to assessment, eight had displayed destruction/disruption of property, and eight had shown physically aggressive behaviors. Repetitive behaviors were prevalent in the sample (with all participants displaying at least one repetitive behavior to a clinically relevant level), as were problems with sleep. Low mood was not prevalent in this group, and nor were overactivity or impulsivity. Full determination of a behavioral phenotype for this group would require a larger sample size, distinguishing between genetic subtypes. However, the current data suggest that ASD characteristics, repetitive, and challenging behaviors (such as aggression and self-injury) might be associated with 19p13.2 microdeletions, providing a basis for future investigation.
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Affiliation(s)
| | | | | | | | | | - Lucy Wilde
- University of Birmingham, Birmingham, UK
| | - Sarah Wynn
- University of Birmingham, Birmingham, UK.,UNIQUE Rare Chromosome Disorder Support Group, London, UK
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114
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Tsou WL, Hosking RR, Burr AA, Sutton JR, Ouyang M, Du X, Gomez CM, Todi SV. DnaJ-1 and karyopherin α3 suppress degeneration in a new Drosophila model of Spinocerebellar Ataxia Type 6. Hum Mol Genet 2015; 24:4385-96. [PMID: 25954029 DOI: 10.1093/hmg/ddv174] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/02/2015] [Accepted: 05/05/2015] [Indexed: 11/15/2022] Open
Abstract
Spinocerebellar ataxia type 6 (SCA6) belongs to the family of CAG/polyglutamine (polyQ)-dependent neurodegenerative disorders. SCA6 is caused by abnormal expansion in a CAG trinucleotide repeat within exon 47 of CACNA1A, a bicistronic gene that encodes α1A, a P/Q-type calcium channel subunit and a C-terminal protein, termed α1ACT. Expansion of the CAG/polyQ region of CACNA1A occurs within α1ACT and leads to ataxia. There are few animal models of SCA6. Here, we describe the generation and characterization of the first Drosophila melanogaster models of SCA6, which express the entire human α1ACT protein with a normal or expanded polyQ. The polyQ-expanded version of α1ACT recapitulates the progressively degenerative nature of SCA6 when expressed in various fly tissues and the presence of densely staining aggregates. Additional studies identify the co-chaperone DnaJ-1 as a potential therapeutic target for SCA6. Expression of DnaJ-1 potently suppresses α1ACT-dependent degeneration and lethality, concomitant with decreased aggregation and reduced nuclear localization of the pathogenic protein. Mutating the nuclear importer karyopherin α3 also leads to reduced toxicity from pathogenic α1ACT. Little is known about the steps leading to degeneration in SCA6 and the means to protect neurons in this disease are lacking. Invertebrate animal models of SCA6 can expand our understanding of molecular sequelae related to degeneration in this disorder and lead to the rapid identification of cellular components that can be targeted to treat it.
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Affiliation(s)
| | | | - Aaron A Burr
- Department of Pharmacology, Cancer Biology Graduate Program and
| | | | | | - Xiaofei Du
- Department of Neurology, University of Chicago School of Medicine, Chicago, IL 60637, USA
| | - Christopher M Gomez
- Department of Neurology, University of Chicago School of Medicine, Chicago, IL 60637, USA
| | - Sokol V Todi
- Department of Pharmacology, Cancer Biology Graduate Program and Department of Neurology, Wayne State University School of Medicine, Detroit, MI 48201, USA and
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115
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Hekman KE, Gomez CM. The autosomal dominant spinocerebellar ataxias: emerging mechanistic themes suggest pervasive Purkinje cell vulnerability. J Neurol Neurosurg Psychiatry 2015; 86:554-61. [PMID: 25136055 PMCID: PMC6718294 DOI: 10.1136/jnnp-2014-308421] [Citation(s) in RCA: 34] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/25/2014] [Accepted: 07/27/2014] [Indexed: 01/05/2023]
Abstract
The spinocerebellar ataxias are a genetically heterogeneous group of disorders with clinically overlapping phenotypes arising from Purkinje cell degeneration, cerebellar atrophy and varying degrees of degeneration of other grey matter regions. For 22 of the 32 subtypes, a genetic cause has been identified. While recurring themes are emerging, there is no clear correlation between the clinical phenotype or penetrance, the type of genetic defect or the category of the disease mechanism, or the neuronal types involved beyond Purkinje cells. These phenomena suggest that cerebellar Purkinje cells may be a uniquely vulnerable neuronal cell type, more susceptible to a wider variety of genetic/cellular insults than most other neuron types.
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Affiliation(s)
- Katherine E Hekman
- Department of Vascular Surgery, McGaw Medical Center of Northwestern University, Chicago, Illinois, USA
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116
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Coutelier M, Stevanin G, Brice A. Genetic landscape remodelling in spinocerebellar ataxias: the influence of next-generation sequencing. J Neurol 2015; 262:2382-95. [DOI: 10.1007/s00415-015-7725-4] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2015] [Revised: 03/25/2015] [Accepted: 03/26/2015] [Indexed: 12/23/2022]
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117
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Cortes CJ, La Spada AR. Autophagy in polyglutamine disease: Imposing order on disorder or contributing to the chaos? Mol Cell Neurosci 2015; 66:53-61. [PMID: 25771431 DOI: 10.1016/j.mcn.2015.03.010] [Citation(s) in RCA: 39] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/26/2015] [Revised: 03/07/2015] [Accepted: 03/09/2015] [Indexed: 12/13/2022] Open
Abstract
Autophagy is an essential, fundamentally important catabolic pathway in which double membrane-bound vesicles form in the cytosol and encircle macromolecules and organelles to permit their degradation after fusion with lysosomes. More than a decade of research has revealed that autophagy is required for normal central nervous system (CNS) function and plays a central role in maintaining protein and organelle quality controls in neurons. Neurodegenerative diseases occur when misfolded proteins accumulate and disrupt normal cellular processes, and autophagy has emerged as a key arbiter of the cell's homeostatic response to this threat. One class of inherited neurodegenerative disease is known as the CAG/polyglutamine repeat disorders, and these diseases all result from the expansion of a CAG repeat tract in the coding regions of distinct genes. Polyglutamine (polyQ) repeat diseases result in the production polyQ-expanded proteins that misfold to form inclusions or aggregates that challenge the main cellular proteostasis system of the cell, the ubiquitin proteasome system (UPS). The UPS cannot efficiently degrade polyQ-expanded disease proteins, and components of the UPS are enriched in polyQ disease aggregate bodies found in degenerating neurons. In addition to components of the UPS, polyQ protein cytosolic aggregates co-localize with key autophagy proteins, even in autophagy deficient cells, suggesting that they probably do not reflect the formation of autophagosomes but rather the sequestration of key autophagy components. Furthermore, recent evidence now implicates polyQ proteins in the regulation of the autophagy pathway itself. Thus, a complex model emerges where polyQ proteins play a dual role as both autophagy substrates and autophagy offenders. In this review, we consider the role of autophagy in polyQ disorders and the therapeutic potential for autophagy modulation in these diseases. This article is part of a Special Issue entitled "Neuronal Protein".
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Affiliation(s)
- Constanza J Cortes
- Department of Pediatrics, University of California, San Diego, La Jolla, CA 92037, USA
| | - Albert R La Spada
- Department of Pediatrics, University of California, San Diego, La Jolla, CA 92037, USA; Department of Cellular & Molecular Medicine, University of California, San Diego, La Jolla, CA 92037, USA; Department of Neurosciences, University of California, San Diego, La Jolla, CA 92037, USA; Division of Biological Sciences, University of California, San Diego, La Jolla, CA 92037, USA; Institute for Genomic Medicine, University of California, San Diego, La Jolla, CA 92037, USA; Sanford Consortium for Regenerative Medicine, University of California, San Diego, La Jolla, CA 92037, USA; Rady Children's Hospital, San Diego, CA 92193, USA.
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118
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Giunti P, Mantuano E, Frontali M, Veneziano L. Molecular mechanism of Spinocerebellar Ataxia type 6: glutamine repeat disorder, channelopathy and transcriptional dysregulation. The multifaceted aspects of a single mutation. Front Cell Neurosci 2015; 9:36. [PMID: 25762895 PMCID: PMC4329791 DOI: 10.3389/fncel.2015.00036] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/01/2014] [Accepted: 01/21/2015] [Indexed: 11/23/2022] Open
Abstract
Spinocerebellar Ataxia type 6 (SCA6) is an autosomal dominant neurodegenerative disease characterized by late onset, slowly progressive, mostly pure cerebellar ataxia. It is one of three allelic disorders associated to CACNA1A gene, coding for the Alpha1 A subunit of P/Q type calcium channel Cav2.1 expressed in the brain, particularly in the cerebellum. The other two disorders are Episodic Ataxia type 2 (EA2), and Familial Hemiplegic Migraine type 1 (FHM1). These disorders show distinct phenotypes that often overlap but have different pathogenic mechanisms. EA2 and FHM1 are due to mutations causing, respectively, a loss and a gain of channel function. SCA6, instead, is associated with short expansions of a polyglutamine stretch located in the cytoplasmic C-terminal tail of the protein. This domain has a relevant role in channel regulation, as well as in transcription regulation of other neuronal genes; thus the SCA6 CAG repeat expansion results in complex pathogenic molecular mechanisms reflecting the complex Cav2.1 C-terminus activity. We will provide a short review for an update on the SCA6 molecular mechanism.
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Affiliation(s)
- Paola Giunti
- Laboratory of Neurogenetics, Department of Molecular Neuroscience, UCL Institute of Neurology London, UK
| | - Elide Mantuano
- Laboratory of Neurogenetics, Institute of Translational Pharmacology, National Research Council of Italy Rome, Italy
| | - Marina Frontali
- Laboratory of Neurogenetics, Institute of Translational Pharmacology, National Research Council of Italy Rome, Italy
| | - Liana Veneziano
- Laboratory of Neurogenetics, Institute of Translational Pharmacology, National Research Council of Italy Rome, Italy
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119
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Marzban H, Del Bigio MR, Alizadeh J, Ghavami S, Zachariah RM, Rastegar M. Cellular commitment in the developing cerebellum. Front Cell Neurosci 2015; 8:450. [PMID: 25628535 PMCID: PMC4290586 DOI: 10.3389/fncel.2014.00450] [Citation(s) in RCA: 94] [Impact Index Per Article: 10.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/13/2014] [Accepted: 12/12/2014] [Indexed: 12/11/2022] Open
Abstract
The mammalian cerebellum is located in the posterior cranial fossa and is critical for motor coordination and non-motor functions including cognitive and emotional processes. The anatomical structure of cerebellum is distinct with a three-layered cortex. During development, neurogenesis and fate decisions of cerebellar primordium cells are orchestrated through tightly controlled molecular events involving multiple genetic pathways. In this review, we will highlight the anatomical structure of human and mouse cerebellum, the cellular composition of developing cerebellum, and the underlying gene expression programs involved in cell fate commitments in the cerebellum. A critical evaluation of the cell death literature suggests that apoptosis occurs in ~5% of cerebellar cells, most shortly after mitosis. Apoptosis and cellular autophagy likely play significant roles in cerebellar development, we provide a comprehensive discussion of their role in cerebellar development and organization. We also address the possible function of unfolded protein response in regulation of cerebellar neurogenesis. We discuss recent advancements in understanding the epigenetic signature of cerebellar compartments and possible connections between DNA methylation, microRNAs and cerebellar neurodegeneration. Finally, we discuss genetic diseases associated with cerebellar dysfunction and their role in the aging cerebellum.
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Affiliation(s)
- Hassan Marzban
- Department of Human Anatomy and Cell Science, University of Manitoba Winnipeg, MB, Canada
| | - Marc R Del Bigio
- Department of Human Anatomy and Cell Science, University of Manitoba Winnipeg, MB, Canada ; Department of Pathology, University of Manitoba Winnipeg, MB, Canada
| | - Javad Alizadeh
- Department of Human Anatomy and Cell Science, University of Manitoba Winnipeg, MB, Canada
| | - Saeid Ghavami
- Department of Human Anatomy and Cell Science, University of Manitoba Winnipeg, MB, Canada
| | - Robby M Zachariah
- Department of Biochemistry and Medical Genetics, University of Manitoba Winnipeg, MB, Canada ; Regenerative Medicine Program, University of Manitoba Winnipeg, MB, Canada
| | - Mojgan Rastegar
- Department of Biochemistry and Medical Genetics, University of Manitoba Winnipeg, MB, Canada ; Regenerative Medicine Program, University of Manitoba Winnipeg, MB, Canada
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120
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Lamandé SR, North KN. Activating internal ribosome entry to treat Duchenne muscular dystrophy. Nat Med 2014; 20:987-8. [PMID: 25198047 DOI: 10.1038/nm.3677] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/22/2023]
Abstract
Mutations in the DMD gene, encoding dystrophin, cause the most common forms of muscular dystrophy. A new study shows that forcing translation of DMD from an internal ribosome entry site can alleviate Duchenne muscular dystrophy symptoms in a mouse model.
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Affiliation(s)
- Shireen R Lamandé
- Murdoch Childrens Research Institute and Department of Paediatrics, University of Melbourne, Royal Children's Hospital, Melbourne, Victoria, Australia
| | - Kathryn N North
- Murdoch Childrens Research Institute and Department of Paediatrics, University of Melbourne, Royal Children's Hospital, Melbourne, Victoria, Australia
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121
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Chopra R, Shakkottai VG. The role for alterations in neuronal activity in the pathogenesis of polyglutamine repeat disorders. Neurotherapeutics 2014; 11:751-63. [PMID: 24986674 PMCID: PMC4391381 DOI: 10.1007/s13311-014-0289-7] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022] Open
Abstract
Polyglutamine diseases are a class of neurodegenerative diseases that share an expansion of a glutamine-encoding CAG tract in the respective disease genes as a central hallmark. In all of these diseases there is progressive degeneration in a select subset of neurons, and the mechanisms behind this degeneration remain unclear. Emerging evidence from animal models of disease has identified abnormalities in synaptic signaling and intrinsic excitability in affected neurons, which coincide with the onset of symptoms and precede apparent neuropathology. The appearance of these early changes suggests that altered neuronal activity might be an important component of network dysfunction and that these alterations in network physiology could contribute to symptoms of disease. Here we review abnormalities in neuronal function that have been identified in both animal models and patients, and highlight ways in which these changes in neuronal activity may contribute to disease symptoms. We then review the literature supporting an emerging role for abnormalities in neuronal activity as a driver of neurodegeneration. Finally, we identify common themes that emerge from studies of neuronal dysfunction in polyglutamine disease.
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Affiliation(s)
- Ravi Chopra
- Department of Neurology, University of Michigan, 109 Zina Pitcher Place, Ann Arbor, MI 48109-2200 USA
| | - Vikram G. Shakkottai
- Department of Neurology, University of Michigan, 109 Zina Pitcher Place, Ann Arbor, MI 48109-2200 USA
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122
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Mohan RD, Abmayr SM, Workman JL. The expanding role for chromatin and transcription in polyglutamine disease. Curr Opin Genet Dev 2014; 26:96-104. [PMID: 25108806 DOI: 10.1016/j.gde.2014.06.008] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/05/2013] [Revised: 06/22/2014] [Accepted: 06/25/2014] [Indexed: 11/28/2022]
Abstract
Nine genetic diseases arise from expansion of CAG repeats in seemingly unrelated genes. They are referred to as polyglutamine (polyQ) diseases due to the presence of elongated glutamine tracts in the corresponding proteins. The pathologic consequences of polyQ expansion include progressive spinal, cerebellar, and neural degeneration. These pathologies are not identical, however, suggesting that disruption of protein-specific functions is crucial to establish and maintain each disease. A closer examination of protein function reveals that several act as regulators of gene expression. Here we examine the roles these proteins play in regulating gene expression, discuss how polyQ expansion may disrupt these functions to cause disease, and speculate on the neural specificity of perturbing ubiquitous gene regulators.
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Affiliation(s)
- Ryan D Mohan
- Stowers Institute for Medical Research, 1000 E 50th St., Kansas City, MO 64110, USA
| | - Susan M Abmayr
- Stowers Institute for Medical Research, 1000 E 50th St., Kansas City, MO 64110, USA.
| | - Jerry L Workman
- Stowers Institute for Medical Research, 1000 E 50th St., Kansas City, MO 64110, USA.
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123
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Rose SJ, Kriener LH, Heinzer AK, Fan X, Raike RS, van den Maagdenberg AMJM, Hess EJ. The first knockin mouse model of episodic ataxia type 2. Exp Neurol 2014; 261:553-62. [PMID: 25109669 DOI: 10.1016/j.expneurol.2014.08.001] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/30/2014] [Revised: 07/07/2014] [Accepted: 08/01/2014] [Indexed: 12/28/2022]
Abstract
Episodic ataxia type 2 (EA2) is an autosomal dominant disorder associated with attacks of ataxia that are typically precipitated by stress, ethanol, caffeine or exercise. EA2 is caused by loss-of-function mutations in the CACNA1A gene, which encodes the α1A subunit of the CaV2.1 voltage-gated Ca(2+) channel. To better understand the pathomechanisms of this disorder in vivo, we created the first genetic animal model of EA2 by engineering a mouse line carrying the EA2-causing c.4486T>G (p.F1406C) missense mutation in the orthologous mouse Cacna1a gene. Mice homozygous for the mutated allele exhibit a ~70% reduction in CaV2.1 current density in Purkinje cells, though surprisingly do not exhibit an overt motor phenotype. Mice hemizygous for the knockin allele (EA2/- mice) did exhibit motor dysfunction measurable by rotarod and pole test. Studies using Cre-flox conditional genetics explored the role of cerebellar Purkinje cells or cerebellar granule cells in the poor motor performance of EA2/- mice and demonstrate that manipulation of either cell type alone did not cause poor motor performance. Thus, it is possible that subtle dysfunction arising from multiple cell types is necessary for the expression of certain ataxia syndromes.
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Affiliation(s)
- Samuel J Rose
- Department of Pharmacology, Emory University School of Medicine, Atlanta, GA 30322, USA
| | - Lisa H Kriener
- Department of Pharmacology, Emory University School of Medicine, Atlanta, GA 30322, USA
| | - Ann K Heinzer
- Department of Neuroscience, Johns Hopkins University School of Medicine, Baltimore, MD 21287, USA
| | - Xueliang Fan
- Department of Pharmacology, Emory University School of Medicine, Atlanta, GA 30322, USA
| | - Robert S Raike
- Department of Pharmacology, Emory University School of Medicine, Atlanta, GA 30322, USA
| | - Arn M J M van den Maagdenberg
- Department of Human Genetics, Leiden University Medical Centre, 2300 RC Leiden, The Netherlands; Department of Neurology, Leiden University Medical Centre, 2300 RC Leiden, The Netherlands
| | - Ellen J Hess
- Department of Pharmacology, Emory University School of Medicine, Atlanta, GA 30322, USA; Department of Neurology, Emory University School of Medicine, Atlanta, GA 30322, USA.
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124
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Affiliation(s)
- Xiaofei Du
- Department of Neurology; University of Chicago; Chicago, IL USA
| | - Bert L Semler
- Department of Microbiology and Molecular Genetics; School of Medicine; University of California, Irvine; Irvine, CA USA
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125
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Dotu I, Lozano G, Clote P, Martinez-Salas E. Using RNA inverse folding to identify IRES-like structural subdomains. RNA Biol 2013; 10:1842-52. [PMID: 24253111 DOI: 10.4161/rna.26994] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022] Open
Abstract
Internal ribosome entry site (IRES) elements govern protein synthesis of mRNAs that bypass cap-dependent translation inhibition under stress conditions. Picornavirus IRES are cis-acting elements, organized in modular domains that recruit the ribosome to internal mRNA sites. The aim of this study was to retrieve short RNA sequences with the capacity to adopt RNA folding patterns conserved with IRES structural subdomains, likely corresponding to RNA modules. We have applied a new program, RNAiFold, an inverse folding algorithm that determines all sequences whose minimum free energy structure is identical to that of the structural domains of interest. Sequences differing by more than 1 nt were clustered. Then, BLASTing one randomly chosen sequence from each cluster of the RNAiFold output, we retrieved viral and cellular sequences among output hits. As a proof of principle, we present the data corresponding to a coding region of Drosophila melanogaster TAF6, a transcription factor-associated protein that contains a structural motif within its coding region potentially folding into an IRES-like subdomain. This RNA region shows a biased codon usage, as predicted from structural constraints at the RNA level, it harbors conserved IRES structural motifs in loops, and interestingly, it has the capacity to confer internal initiation of translation in tissue culture cells.
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Affiliation(s)
- Ivan Dotu
- Biology Department; Boston College; Chestnut Hill, MA USA
| | - Gloria Lozano
- Centro de Biologia Molecular Severo Ochoa; Consejo Superior de Investigaciones Cientificas-Universidad Autonoma de Madrid; Madrid, Spain
| | - Peter Clote
- Biology Department; Boston College; Chestnut Hill, MA USA
| | - Encarnacion Martinez-Salas
- Centro de Biologia Molecular Severo Ochoa; Consejo Superior de Investigaciones Cientificas-Universidad Autonoma de Madrid; Madrid, Spain
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126
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Martínez-Salas E, Lozano G, Fernandez-Chamorro J, Francisco-Velilla R, Galan A, Diaz R. RNA-binding proteins impacting on internal initiation of translation. Int J Mol Sci 2013; 14:21705-26. [PMID: 24189219 PMCID: PMC3856030 DOI: 10.3390/ijms141121705] [Citation(s) in RCA: 46] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/06/2013] [Revised: 10/17/2013] [Accepted: 10/22/2013] [Indexed: 12/20/2022] Open
Abstract
RNA-binding proteins (RBPs) are pivotal regulators of all the steps of gene expression. RBPs govern gene regulation at the post-transcriptional level by virtue of their capacity to assemble ribonucleoprotein complexes on certain RNA structural elements, both in normal cells and in response to various environmental stresses. A rapid cellular response to stress conditions is triggered at the step of translation initiation. Two basic mechanisms govern translation initiation in eukaryotic mRNAs, the cap-dependent initiation mechanism that operates in most mRNAs, and the internal ribosome entry site (IRES)-dependent mechanism activated under conditions that compromise the general translation pathway. IRES elements are cis-acting RNA sequences that recruit the translation machinery using a cap-independent mechanism often assisted by a subset of translation initiation factors and various RBPs. IRES-dependent initiation appears to use different strategies to recruit the translation machinery depending on the RNA organization of the region and the network of RBPs interacting with the element. In this review we discuss recent advances in understanding the implications of RBPs on IRES-dependent translation initiation.
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Affiliation(s)
- Encarnación Martínez-Salas
- Centro de Biología Molecular Severo Ochoa, Consejo Superior de Investigaciones Científicas-Universidad Autónoma de Madrid, Cantoblanco, Madrid 28049, Spain.
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127
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Zameel Cader M. The molecular pathogenesis of migraine: new developments and opportunities. Hum Mol Genet 2013; 22:R39-44. [DOI: 10.1093/hmg/ddt364] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022] Open
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128
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Nelson DL, Orr HT, Warren ST. The unstable repeats--three evolving faces of neurological disease. Neuron 2013; 77:825-43. [PMID: 23473314 PMCID: PMC3608403 DOI: 10.1016/j.neuron.2013.02.022] [Citation(s) in RCA: 152] [Impact Index Per Article: 13.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 02/20/2013] [Indexed: 01/08/2023]
Abstract
Disorders characterized by expansion of an unstable nucleotide repeat account for a number of inherited neurological diseases. Here, we review examples of unstable repeat disorders that nicely illustrate three of the major pathogenic mechanisms associated with these diseases: loss of function typically by disrupting transcription of the mutated gene, RNA toxic gain of function, and protein toxic gain of function. In addition to providing insight into the mechanisms underlying these devastating neurological disorders, the study of these unstable microsatellite repeat disorders has provided insight into very basic aspects of neuroscience.
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Affiliation(s)
- David L. Nelson
- Department of Molecular and Human Genetics, Baylor College
of Medicine, Houston, TX 77030
| | - Harry T. Orr
- Department of Laboratory Medicine and Pathology, University
of Minnesota, Minneapolis, MN 55455
| | - Stephen T. Warren
- Department of Human Genetics, Emory University School of
Medicine, Atlanta, GA 30322
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