51
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Figueroa-Romero C, Hur J, Lunn JS, Paez-Colasante X, Bender DE, Yung R, Sakowski SA, Feldman EL. Expression of microRNAs in human post-mortem amyotrophic lateral sclerosis spinal cords provides insight into disease mechanisms. Mol Cell Neurosci 2015; 71:34-45. [PMID: 26704906 DOI: 10.1016/j.mcn.2015.12.008] [Citation(s) in RCA: 52] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/27/2015] [Revised: 11/23/2015] [Accepted: 12/14/2015] [Indexed: 12/12/2022] Open
Abstract
Amyotrophic lateral sclerosis is a late-onset and terminal neurodegenerative disease. The majority of cases are sporadic with unknown causes and only a small number of cases are genetically linked. Recent evidence suggests that post-transcriptional regulation and epigenetic mechanisms, such as microRNAs, underlie the onset and progression of neurodegenerative disorders; therefore, altered microRNA expression may result in the dysregulation of key genes and biological pathways that contribute to the development of sporadic amyotrophic lateral sclerosis. Using systems biology analyses on postmortem human spinal cord tissue, we identified dysregulated mature microRNAs and their potential targets previously implicated in functional process and pathways associated with the pathogenesis of ALS. Furthermore, we report a global reduction of mature microRNAs, alterations in microRNA processing, and support for a role of the nucleotide binding protein, TAR DNA binding protein 43, in regulating sporadic amyotrophic lateral sclerosis-associated microRNAs, thereby offering a potential underlying mechanism for sporadic amyotrophic lateral sclerosis.
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Affiliation(s)
| | - Junguk Hur
- Department of Neurology, University of Michigan, Ann Arbor, MI 48109 USA
| | - J Simon Lunn
- Department of Neurology, University of Michigan, Ann Arbor, MI 48109 USA
| | | | - Diane E Bender
- Department of Neurology, University of Michigan, Ann Arbor, MI 48109 USA
| | - Raymond Yung
- Division of Geriatrics and Palliative Medicine, Department of Internal Medicine, University of Michigan, Ann Arbor, MI 48109, USA.,Geriatric Research, Education and Clinical Care Center, VA Ann Arbor Health System, Ann Arbor, MI 48105, USA
| | - Stacey A Sakowski
- A. Alfred Taubman Medical Research Institute, University of Michigan, Ann Arbor, MI 48109, USA
| | - Eva L Feldman
- Department of Neurology, University of Michigan, Ann Arbor, MI 48109 USA.,A. Alfred Taubman Medical Research Institute, University of Michigan, Ann Arbor, MI 48109, USA
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52
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Yan J, Zhang H, Liu Y, Zhao F, Zhu S, Xie C, Tang TS, Guo C. Germline deletion of huntingtin causes male infertility and arrested spermiogenesis in mice. J Cell Sci 2015; 129:492-501. [PMID: 26659666 DOI: 10.1242/jcs.173666] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/29/2015] [Accepted: 12/07/2015] [Indexed: 01/28/2023] Open
Abstract
Human Huntingtin (HTT), a Huntington's disease gene, is highly expressed in the mammalian brain and testis. Simultaneous knockout of mouse Huntingtin (Htt) in brain and testis impairs male fertility, providing evidence for a link between Htt and spermatogenesis; however, the underlying mechanism remains unclear. To understand better the function of Htt in spermatogenesis, we restricted the genetic deletion specifically to the germ cells using the Cre/loxP site-specific recombination strategy and found that the resulting mice manifested smaller testes, azoospermia and complete male infertility. Meiotic chromosome spread experiments showed that the process of meiosis was normal in the absence of Htt. Notably, we found that Htt-deficient round spermatids did not progress beyond step 3 during the post-meiotic phase, when round spermatids differentiate into mature spermatozoa. Using an iTRAQ-based quantitative proteomic assay, we found that knockout of Htt significantly altered the testis protein profile. The differentially expressed proteins exhibited a remarkable enrichment for proteins involved in translation regulation and DNA packaging, suggesting that Htt might play a role in spermatogenesis by regulating translation and DNA packaging in the testis.
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Affiliation(s)
- Jinting Yan
- CAS Key Laboratory of Genomic and Precision Medicine, China Gastrointestinal Cancer Research Center, Beijing Institute of Genomics, Chinese Academy of Sciences, Beijing 100101, China
| | - Hui Zhang
- CAS Key Laboratory of Genomic and Precision Medicine, China Gastrointestinal Cancer Research Center, Beijing Institute of Genomics, Chinese Academy of Sciences, Beijing 100101, China
| | - Yang Liu
- CAS Key Laboratory of Genomic and Precision Medicine, China Gastrointestinal Cancer Research Center, Beijing Institute of Genomics, Chinese Academy of Sciences, Beijing 100101, China
| | - Feilong Zhao
- CAS Key Laboratory of Genomic and Precision Medicine, China Gastrointestinal Cancer Research Center, Beijing Institute of Genomics, Chinese Academy of Sciences, Beijing 100101, China
| | - Shu Zhu
- State Key Laboratory of Membrane Biology, Institute of Zoology, Chinese Academy of Sciences, Beijing 100101, China
| | - Chengmei Xie
- CAS Key Laboratory of Genomic and Precision Medicine, China Gastrointestinal Cancer Research Center, Beijing Institute of Genomics, Chinese Academy of Sciences, Beijing 100101, China
| | - Tie-Shan Tang
- State Key Laboratory of Membrane Biology, Institute of Zoology, Chinese Academy of Sciences, Beijing 100101, China
| | - Caixia Guo
- CAS Key Laboratory of Genomic and Precision Medicine, China Gastrointestinal Cancer Research Center, Beijing Institute of Genomics, Chinese Academy of Sciences, Beijing 100101, China
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53
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Tang AY. RNA processing-associated molecular mechanisms of neurodegenerative diseases. J Appl Genet 2015; 57:323-33. [DOI: 10.1007/s13353-015-0330-5] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/02/2015] [Revised: 11/22/2015] [Accepted: 11/26/2015] [Indexed: 12/13/2022]
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54
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Gupta S, Verma S, Mantri S, Berman NE, Sandhir R. Targeting MicroRNAs in Prevention and Treatment of Neurodegenerative Disorders. Drug Dev Res 2015; 76:397-418. [PMID: 26359796 DOI: 10.1002/ddr.21277] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
Preclinical Research microRNAs (miRNAs) are small noncoding RNAs (ncRNAs) that are key regulators of gene expression. They act on wide range of targets by binding to mRNA via imperfect complementarity at 3' UTR. Evidence suggests that miRNAs regulate many biological processes including neuronal development, differentiation, and disease. Altered expression of several miRNAs has been reported in many neurodegenerative disorders (NDDs). Many miRNAs are altered in these diseases, but miRNA 15, miRNA 21, and miRNA 146a have been shown to play critical role in many neurodegenerative conditions. As these miRNAs regulate many genes, miRNA targeted approaches would allow concurrently targeting of multiple effectors of pathways that regulate disease progression. In this review, we describe the role of miRNAs in various NDDs and their potential as therapeutic tools in prevention and treatment of neurological conditions.
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Affiliation(s)
- Smriti Gupta
- Department of Biochemistry, Panjab University, Chandigarh, 160014, India
| | - Savita Verma
- Department of Biochemistry, Panjab University, Chandigarh, 160014, India
| | - Shrikant Mantri
- Computational Biology Laboratory, National Agri-Food Biotechnology Institute, Mohali, Punjab, 160071, India
| | - Nancy E Berman
- Department of Anatomy & Cell Biology, Kansas University Medical Center, 3901 Rainbow Blvd., Kansas City, KS 66160, USA
| | - Rajat Sandhir
- Department of Biochemistry, Panjab University, Chandigarh, 160014, India
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55
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Wen X, Tan W, Westergard T, Krishnamurthy K, Markandaiah SS, Shi Y, Lin S, Shneider NA, Monaghan J, Pandey UB, Pasinelli P, Ichida JK, Trotti D. Antisense proline-arginine RAN dipeptides linked to C9ORF72-ALS/FTD form toxic nuclear aggregates that initiate in vitro and in vivo neuronal death. Neuron 2015; 84:1213-25. [PMID: 25521377 DOI: 10.1016/j.neuron.2014.12.010] [Citation(s) in RCA: 403] [Impact Index Per Article: 44.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 12/03/2014] [Indexed: 12/13/2022]
Abstract
Expanded GGGGCC (G4C2) nucleotide repeats within the C9ORF72 gene are the most common genetic mutation associated with both amyotrophic lateral sclerosis (ALS) and frontotemporal dementia (FTD). Sense and antisense transcripts of these expansions are translated to form five dipeptide repeat proteins (DRPs). We employed primary cortical and motor neuron cultures, live-cell imaging, and transgenic fly models and found that the arginine-rich dipeptides, in particular Proline-Arginine (PR), are potently neurotoxic. Factors that anticipated their neurotoxicity included aggregation in nucleoli, decreased number of processing bodies, and stress granule formation, implying global translational dysregulation as path accountable for toxicity. Nuclear PR aggregates were also found in human induced motor neurons and postmortem spinal cord tissues from C9ORF72 ALS and ALS/FTD patients. Intronic G4C2 transcripts, but not loss of C9ORF72 protein, are also toxic to motor and cortical neurons. Interestingly, G4C2 transcript-mediated neurotoxicity synergizes with that of PR aggregates, suggesting convergence of mechanisms.
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Affiliation(s)
- Xinmei Wen
- Frances and Joseph Weinberg Unit for ALS Research, Department of Neuroscience, Thomas Jefferson University, 900 Walnut Street, Philadelphia, PA 19107, USA
| | - Wenzhi Tan
- Frances and Joseph Weinberg Unit for ALS Research, Department of Neuroscience, Thomas Jefferson University, 900 Walnut Street, Philadelphia, PA 19107, USA
| | - Thomas Westergard
- Frances and Joseph Weinberg Unit for ALS Research, Department of Neuroscience, Thomas Jefferson University, 900 Walnut Street, Philadelphia, PA 19107, USA
| | - Karthik Krishnamurthy
- Frances and Joseph Weinberg Unit for ALS Research, Department of Neuroscience, Thomas Jefferson University, 900 Walnut Street, Philadelphia, PA 19107, USA
| | - Shashirekha S Markandaiah
- Frances and Joseph Weinberg Unit for ALS Research, Department of Neuroscience, Thomas Jefferson University, 900 Walnut Street, Philadelphia, PA 19107, USA
| | - Yingxiao Shi
- Department of Stem Cell Biology and Regenerative Medicine, Eli and Edythe Broad Center for Regenerative Medicine and Stem Cell Research, University of Southern California, Los Angeles, CA 90089, USA
| | - Shaoyu Lin
- Department of Stem Cell Biology and Regenerative Medicine, Eli and Edythe Broad Center for Regenerative Medicine and Stem Cell Research, University of Southern California, Los Angeles, CA 90089, USA
| | - Neil A Shneider
- Department of Neurology, The Center for Motor Neuron Biology and Disease, Columbia University Medical Center, New York, NY 10032, USA
| | - John Monaghan
- Department of Pediatrics, Child Neurology and Neurobiology, Children's Hospital of Pittsburgh, University of Pittsburgh Medical Center, One Children's Hospital Drive, 4401 Penn Avenue, Pittsburgh, PA 15224, USA
| | - Udai B Pandey
- Department of Pediatrics, Child Neurology and Neurobiology, Children's Hospital of Pittsburgh, University of Pittsburgh Medical Center, One Children's Hospital Drive, 4401 Penn Avenue, Pittsburgh, PA 15224, USA
| | - Piera Pasinelli
- Frances and Joseph Weinberg Unit for ALS Research, Department of Neuroscience, Thomas Jefferson University, 900 Walnut Street, Philadelphia, PA 19107, USA
| | - Justin K Ichida
- Department of Stem Cell Biology and Regenerative Medicine, Eli and Edythe Broad Center for Regenerative Medicine and Stem Cell Research, University of Southern California, Los Angeles, CA 90089, USA
| | - Davide Trotti
- Frances and Joseph Weinberg Unit for ALS Research, Department of Neuroscience, Thomas Jefferson University, 900 Walnut Street, Philadelphia, PA 19107, USA.
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56
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Walsh MJ, Cooper-Knock J, Dodd JE, Stopford MJ, Mihaylov SR, Kirby J, Shaw PJ, Hautbergue GM. Invited review: decoding the pathophysiological mechanisms that underlie RNA dysregulation in neurodegenerative disorders: a review of the current state of the art. Neuropathol Appl Neurobiol 2015; 41:109-34. [PMID: 25319671 PMCID: PMC4329338 DOI: 10.1111/nan.12187] [Citation(s) in RCA: 35] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/06/2014] [Accepted: 10/07/2014] [Indexed: 12/12/2022]
Abstract
Altered RNA metabolism is a key pathophysiological component causing several neurodegenerative diseases. Genetic mutations causing neurodegeneration occur in coding and noncoding regions of seemingly unrelated genes whose products do not always contribute to the gene expression process. Several pathogenic mechanisms may coexist within a single neuronal cell, including RNA/protein toxic gain-of-function and/or protein loss-of-function. Genetic mutations that cause neurodegenerative disorders disrupt healthy gene expression at diverse levels, from chromatin remodelling, transcription, splicing, through to axonal transport and repeat-associated non-ATG (RAN) translation. We address neurodegeneration in repeat expansion disorders [Huntington's disease, spinocerebellar ataxias, C9ORF72-related amyotrophic lateral sclerosis (ALS)] and in diseases caused by deletions or point mutations (spinal muscular atrophy, most subtypes of familial ALS). Some neurodegenerative disorders exhibit broad dysregulation of gene expression with the synthesis of hundreds to thousands of abnormal messenger RNA (mRNA) molecules. However, the number and identity of aberrant mRNAs that are translated into proteins - and how these lead to neurodegeneration - remain unknown. The field of RNA biology research faces the challenge of identifying pathophysiological events of dysregulated gene expression. In conclusion, we discuss current research limitations and future directions to improve our characterization of pathological mechanisms that trigger disease onset and progression.
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Affiliation(s)
- M J Walsh
- Sheffield Institute for Translational Neuroscience (SITraN), Department of Neuroscience, University of SheffieldSheffield, UK
| | - J Cooper-Knock
- Sheffield Institute for Translational Neuroscience (SITraN), Department of Neuroscience, University of SheffieldSheffield, UK
| | - J E Dodd
- Sheffield Institute for Translational Neuroscience (SITraN), Department of Neuroscience, University of SheffieldSheffield, UK
| | - M J Stopford
- Sheffield Institute for Translational Neuroscience (SITraN), Department of Neuroscience, University of SheffieldSheffield, UK
| | - S R Mihaylov
- Sheffield Institute for Translational Neuroscience (SITraN), Department of Neuroscience, University of SheffieldSheffield, UK
| | - J Kirby
- Sheffield Institute for Translational Neuroscience (SITraN), Department of Neuroscience, University of SheffieldSheffield, UK
| | - P J Shaw
- Sheffield Institute for Translational Neuroscience (SITraN), Department of Neuroscience, University of SheffieldSheffield, UK
| | - G M Hautbergue
- Sheffield Institute for Translational Neuroscience (SITraN), Department of Neuroscience, University of SheffieldSheffield, UK
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57
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Qiu L, Tan EK, Zeng L. microRNAs and Neurodegenerative Diseases. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2015; 888:85-105. [PMID: 26663180 DOI: 10.1007/978-3-319-22671-2_6] [Citation(s) in RCA: 67] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
microRNAs (miRNAs) are small, noncoding RNA molecules that through imperfect base-pairing with complementary sequences of target mRNA molecules, typically cleave target mRNA, causing subsequent degradation or translation inhibition. Although an increasing number of studies have identified misregulated miRNAs in the neurodegenerative diseases (NDDs) Alzheimer's disease, Parkinson's disease, Huntington's disease, and amyotrophic lateral sclerosis, which suggests that alterations in the miRNA regulatory pathway could contribute to disease pathogenesis, the molecular mechanisms underlying the pathological implications of misregulated miRNA expression and the regulation of the key genes involved in NDDs remain largely unknown. In this chapter, we provide evidence of the function and regulation of miRNAs and their association with the neurological events in NDDs. This will help improve our understanding of how miRNAs govern the biological functions of key pathogenic genes in these diseases, which potentially regulate several pathways involved in the progression of neurodegeneration. Additionally, given the growing interest in the therapeutic potential of miRNAs, we discuss current clinical challenges to developing miRNA-based therapeutics for NDDs.
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Affiliation(s)
- Lifeng Qiu
- Neural Stem Cell Research Lab, Department of Research, National Neuroscience Institute, Singapore, 308433, Singapore
| | - Eng King Tan
- Department of Neurology, National Neuroscience Institute, SGH Campus, Singapore, 169856, Singapore
- Department of Research, National Neuroscience Institute, 11 Jalan Tan Tock Seng, Singapore, 308433, Singapore
- Neuroscience and Behavioral Disorders program, Duke-National University of Singapore, Graduate Medical School, Singapore, 169857, Singapore
| | - Li Zeng
- Neural Stem Cell Research Lab, Department of Research, National Neuroscience Institute, Singapore, 308433, Singapore.
- Department of Research, National Neuroscience Institute, 11 Jalan Tan Tock Seng, Singapore, 308433, Singapore.
- Neuroscience and Behavioral Disorders program, Duke-National University of Singapore, Graduate Medical School, Singapore, 169857, Singapore.
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58
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The Emerging Role of MitomiRs in the Pathophysiology of Human Disease. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2015; 888:123-54. [DOI: 10.1007/978-3-319-22671-2_8] [Citation(s) in RCA: 52] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
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59
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Kamal MA, Mushtaq G, Greig NH. Current Update on Synopsis of miRNA Dysregulation in Neurological Disorders. CNS & NEUROLOGICAL DISORDERS DRUG TARGETS 2015; 14:492-501. [PMID: 25714967 PMCID: PMC5878050 DOI: 10.2174/1871527314666150225143637] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/15/2014] [Revised: 12/04/2014] [Accepted: 12/04/2014] [Indexed: 02/07/2023]
Abstract
Aberrant expression of microRNAs (miRNAs) has been implicated in various neurological disorders (NDs) of the central nervous system such as Alzheimer disease, Parkinson's disease, Huntington disease, amyotrophic lateral sclerosis, schizophrenia and autism. If dysregulated miRNAs are identified in patients suffering from NDs, this may serve as a biomarker for the earlier diagnosis and monitoring of disease progression. Identifying the role of miRNAs in normal cellular processes and understanding how dysregulated miRNA expression is responsible for their neurological effects is also critical in the development of new therapeutic strategies for NDs. miRNAs hold great promise from a therapeutic point of view especially if it can be proved that a single miRNA has the ability to influence several target genes, making it possible for the researchers to potentially modify a whole disease phenotype by modulating a single miRNA molecule. Hence, better understanding of the mechanisms by which miRNA play a role in the pathogenesis of NDs may provide novel targets to scientists and researchers for innovative therapies.
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Affiliation(s)
- Mohammad A. Kamal
- King Fahd Medical Research Center, King Abdulaziz University, P. O. Box 80216, Jeddah 21589, Saudi Arabia
| | - Gohar Mushtaq
- Department of Biochemistry, College of Science, King Abdulaziz University, Jeddah, Saudi Arabia
| | - Nigel H. Greig
- Drug Design & Development Section, Translational Gerontology Branch, Intramural Research Program, National Institute on Aging, National Institutes of Health, Biomedical Research Center, 251 Bayview Boulevard, Baltimore, MD 21224, USA
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60
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Potential function for the Huntingtin protein as a scaffold for selective autophagy. Proc Natl Acad Sci U S A 2014; 111:16889-94. [PMID: 25385587 DOI: 10.1073/pnas.1420103111] [Citation(s) in RCA: 197] [Impact Index Per Article: 19.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/18/2023] Open
Abstract
Although dominant gain-of-function triplet repeat expansions in the Huntingtin (HTT) gene are the underlying cause of Huntington disease (HD), understanding the normal functions of nonmutant HTT protein has remained a challenge. We report here findings that suggest that HTT plays a significant role in selective autophagy. Loss of HTT function in Drosophila disrupts starvation-induced autophagy in larvae and conditional knockout of HTT in the mouse CNS causes characteristic cellular hallmarks of disrupted autophagy, including an accumulation of striatal p62/SQSTM1 over time. We observe that specific domains of HTT have structural similarities to yeast Atg proteins that function in selective autophagy, and in particular that the C-terminal domain of HTT shares structural similarity to yeast Atg11, an autophagic scaffold protein. To explore possible functional similarity between HTT and Atg11, we investigated whether the C-terminal domain of HTT interacts with mammalian counterparts of yeast Atg11-interacting proteins. Strikingly, this domain of HTT coimmunoprecipitates with several key Atg11 interactors, including the Atg1/Unc-51-like autophagy activating kinase 1 kinase complex, autophagic receptor proteins, and mammalian Atg8 homologs. Mutation of a phylogenetically conserved WXXL domain in a C-terminal HTT fragment reduces coprecipitation with mammalian Atg8 homolog GABARAPL1, suggesting a direct interaction. Collectively, these data support a possible central role for HTT as an Atg11-like scaffold protein. These findings have relevance to both mechanisms of disease pathogenesis and to therapeutic intervention strategies that reduce levels of both mutant and normal HTT.
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61
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Pryor WM, Biagioli M, Shahani N, Swarnkar S, Huang WC, Page DT, MacDonald ME, Subramaniam S. Huntingtin promotes mTORC1 signaling in the pathogenesis of Huntington's disease. Sci Signal 2014; 7:ra103. [DOI: 10.1126/scisignal.2005633] [Citation(s) in RCA: 84] [Impact Index Per Article: 8.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
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62
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Qiu L, Zhang W, Tan EK, Zeng L. Deciphering the function and regulation of microRNAs in Alzheimer's disease and Parkinson's disease. ACS Chem Neurosci 2014; 5:884-94. [PMID: 25210999 DOI: 10.1021/cn500149w] [Citation(s) in RCA: 42] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022] Open
Abstract
MicroRNAs (miRNAs) are single stranded, noncoding RNA molecules that are encoded by eukaryotic nuclear DNA. miRNAs function through imperfect base-pairing with complementary sequences of target mRNA molecules, which is typically via the cleavage of target mRNA with transcriptional repression or translational degradation. An increasing number of studies identified dysregulation of miRNAs in neurodegenerative disease and suggest that alterations in the miRNA regulatory pathway could contribute to the disease pathogenesis. However, molecular mechanisms underlying the pathological implications of dysregulated miRNA expression and regulation of the key genes that are involved in neurodegenerative diseases remain largely unknown. Here, we review the evidence for the functional role of dysregulated miRNAs involved in disease pathogenesis, as well as how miRNAs govern neuronal functions either upstream or downstream of target genes that are disease pathogenic factors. Furthermore, we review the cellular feedback regulation between miRNAs and target genes in neurodegenerative diseases, with a focus on Alzheimer's disease and Parkinson's disease.
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Affiliation(s)
- Lifeng Qiu
- Neural
Stem Cell Research Lab, Research Department, National Neuroscience Institute, 308433, Singapore
| | - Wei Zhang
- Neural
Stem Cell Research Lab, Research Department, National Neuroscience Institute, 308433, Singapore
| | - Eng King Tan
- Department
of Neurology, National Neuroscience Institute, SGH Campus, 169856, Singapore
- Research
Department, National Neuroscience Institute, 308433, Singapore
- Neuroscience & Behavioral Disorders Program, DUKE-NUS Graduate Medical School, 169857, Singapore
| | - Li Zeng
- Neural
Stem Cell Research Lab, Research Department, National Neuroscience Institute, 308433, Singapore
- Neuroscience & Behavioral Disorders Program, DUKE-NUS Graduate Medical School, 169857, Singapore
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63
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Rajgor D, Mellad JA, Soong D, Rattner JB, Fritzler MJ, Shanahan CM. Mammalian microtubule P-body dynamics are mediated by nesprin-1. ACTA ACUST UNITED AC 2014; 205:457-75. [PMID: 24862572 PMCID: PMC4033771 DOI: 10.1083/jcb.201306076] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Abstract
Nesprins are a multi-isomeric family of spectrin-repeat (SR) proteins, predominantly known as nuclear envelope scaffolds. However, isoforms that function beyond the nuclear envelope remain poorly examined. Here, we characterize p50(Nesp1), a 50-kD isoform that localizes to processing bodies (PBs), where it acts as a microtubule-associated protein capable of linking mRNP complexes to microtubules. Overexpression of dominant-negative p50(Nesp1) caused Rck/p54, but not GW182, displacement from microtubules, resulting in reduced PB movement and cross talk with stress granules (SGs). These cells disassembled canonical SGs induced by sodium arsenite, but not those induced by hydrogen peroxide, leading to cell death and revealing PB-microtubule attachment is required for hydrogen peroxide-induced SG anti-apoptotic functions. Furthermore, p50(Nesp1) was required for miRNA-mediated silencing and interacted with core miRISC silencers Ago2 and Rck/p54 in an RNA-dependent manner and with GW182 in a microtubule-dependent manner. These data identify p50(Nesp1) as a multi-functional PB component and microtubule scaffold necessary for RNA granule dynamics and provides evidence for PB and SG micro-heterogeneity.
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Affiliation(s)
- Dipen Rajgor
- Cardiovascular Division, BHF Centre of Excellence, James Black Centre, King's College London, London SE5 9NU, England, UK
| | - Jason A Mellad
- Cardiovascular Division, BHF Centre of Excellence, James Black Centre, King's College London, London SE5 9NU, England, UK
| | - Daniel Soong
- Cardiovascular Division, BHF Centre of Excellence, James Black Centre, King's College London, London SE5 9NU, England, UK
| | - Jerome B Rattner
- Department of Biochemistry and Molecular Biology, University of Calgary, Calgary T2N 4N1, Alberta, Canada
| | - Marvin J Fritzler
- Department of Biochemistry and Molecular Biology, University of Calgary, Calgary T2N 4N1, Alberta, Canada
| | - Catherine M Shanahan
- Cardiovascular Division, BHF Centre of Excellence, James Black Centre, King's College London, London SE5 9NU, England, UK
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64
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Koscianska E, Krzyzosiak WJ. Current understanding of the role of microRNAs in spinocerebellar ataxias. CEREBELLUM & ATAXIAS 2014; 1:7. [PMID: 26331031 PMCID: PMC4552431 DOI: 10.1186/2053-8871-1-7] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 03/11/2014] [Accepted: 05/30/2014] [Indexed: 12/21/2022]
Abstract
The number of studies highlighting the role of microRNAs (miRNAs) in human physiology and diseases is growing, but many miRNA-driven regulatory mechanisms remain elusive. A proper understanding of the exact functions of individual miRNAs and their interaction with specific targets is vitally important because such knowledge might help cure diseases for which no effective treatment currently exists. Herein, we present current views on the role of the miRNA-mediated regulation of gene expression in the case of select spinocerebellar ataxias (SCAs) and their potential involvement in the pathogenesis of these diseases. Specifically, we summarize published data showing the known links between miRNAs and CAG repeat-dependent SCAs. Moreover, using the example of SCA type 3 (SCA3), we refer to the issue of prediction and validation of miRNA targets, and we demonstrate that miR-181a-1 may regulate the 3'-UTR of the ATXN3 gene.
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Affiliation(s)
- Edyta Koscianska
- Department of Molecular Biomedicine, Institute of Bioorganic Chemistry, Polish Academy of Sciences, Noskowskiego 12/14 Str, 61-704 Poznan, Poland
| | - Wlodzimierz J Krzyzosiak
- Department of Molecular Biomedicine, Institute of Bioorganic Chemistry, Polish Academy of Sciences, Noskowskiego 12/14 Str, 61-704 Poznan, Poland
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65
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Tan L, Yu JT, Tan L. Causes and Consequences of MicroRNA Dysregulation in Neurodegenerative Diseases. Mol Neurobiol 2014; 51:1249-62. [PMID: 24973986 DOI: 10.1007/s12035-014-8803-9] [Citation(s) in RCA: 92] [Impact Index Per Article: 9.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/13/2014] [Accepted: 06/22/2014] [Indexed: 12/12/2022]
Abstract
Neurodegenerative diseases, including Alzheimer's disease (AD), Parkinson's disease (PD), Huntington's disease (HD) and amyotrophic lateral sclerosis (ALS), originate from a loss of neurons in the central nervous system (CNS) and are severely debilitating. The incidence of neurodegenerative diseases increases with age, and they are expected to become more common due to extended life expectancy. Because of no clear mechanisms, these diseases have become a major challenge in neurobiology. It is well recognized that these disorders become the culmination of many different genetic and environmental influences. Prior studies have shown that microRNAs (miRNAs) are pathologically altered during the inexorable course of some neurodegenerative diseases, suggesting that miRNAs may be the contributing factor in neurodegeneration. Here, we review what is known about the involvement of miRNAs in the pathogenesis of neurodegenerative diseases. The biogenesis of miRNAs and various functions of miRNAs that act as the chief regulators will be discussed. We focus in particular on dysregulation of miRNAs which leads to several neurodegenerative diseases from three aspects: miRNA-generating disorders, miRNA-targeting genes and epigenetic alterations. Furthermore, recent evidences have shown that circulating miRNA expression levels are changed in patients with neurodegenerative diseases. Circulating miRNA expression levels are reported in patients in order to evaluate their application as biomarkers of these diseases. A discussion is included with a potential diagnostic biomarker and the possible future direction in exploring the nexus between miRNAs and various neurodegenerative diseases.
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Affiliation(s)
- Lin Tan
- College of Medicine and Pharmaceutics, Ocean University of China, Qingdao, China
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Thomas MG, Pascual ML, Maschi D, Luchelli L, Boccaccio GL. Synaptic control of local translation: the plot thickens with new characters. Cell Mol Life Sci 2014; 71:2219-39. [PMID: 24212248 PMCID: PMC11113725 DOI: 10.1007/s00018-013-1506-y] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/09/2013] [Revised: 10/11/2013] [Accepted: 10/21/2013] [Indexed: 12/18/2022]
Abstract
The production of proteins from mRNAs localized at the synapse ultimately controls the strength of synaptic transmission, thereby affecting behavior and cognitive functions. The regulated transcription, processing, and transport of mRNAs provide dynamic control of the dendritic transcriptome, which includes thousands of messengers encoding multiple cellular functions. Translation is locally modulated by synaptic activity through a complex network of RNA-binding proteins (RBPs) and various types of non-coding RNAs (ncRNAs) including BC-RNAs, microRNAs, piwi-interacting RNAs, and small interference RNAs. The RBPs FMRP and CPEB play a well-established role in synaptic translation, and additional regulatory factors are emerging. The mRNA repressors Smaug, Nanos, and Pumilio define a novel pathway for local translational control that affects dendritic branching and spines in both flies and mammals. Recent findings support a role for processing bodies and related synaptic mRNA-silencing foci (SyAS-foci) in the modulation of synaptic plasticity and memory formation. The SyAS-foci respond to different stimuli with changes in their integrity thus enabling regulated mRNA release followed by translation. CPEB, Pumilio, TDP-43, and FUS/TLS form multimers through low-complexity regions related to prion domains or polyQ expansions. The oligomerization of these repressor RBPs is mechanistically linked to the aggregation of abnormal proteins commonly associated with neurodegeneration. Here, we summarize the current knowledge on how specificity in mRNA translation is achieved through the concerted action of multiple pathways that involve regulatory ncRNAs and RBPs, the modification of translation factors, and mRNA-silencing foci dynamics.
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Affiliation(s)
- María Gabriela Thomas
- Instituto Leloir, Av. Patricias Argentinas 435, C1405BWE Buenos Aires, Argentina
- IIBBA-CONICET, C1405BWE Buenos Aires, Argentina
| | - Malena Lucía Pascual
- Instituto Leloir, Av. Patricias Argentinas 435, C1405BWE Buenos Aires, Argentina
- IIBBA-CONICET, C1405BWE Buenos Aires, Argentina
- Facultad de Ciencias Exactas y Naturales, University of Buenos Aires, Buenos Aires, Argentina
| | - Darío Maschi
- Instituto Leloir, Av. Patricias Argentinas 435, C1405BWE Buenos Aires, Argentina
- Present Address: Department of Cell Biology and Physiology, Washington University School of Medicine, St. Louis, MO USA
| | - Luciana Luchelli
- Instituto Leloir, Av. Patricias Argentinas 435, C1405BWE Buenos Aires, Argentina
- IIBBA-CONICET, C1405BWE Buenos Aires, Argentina
| | - Graciela Lidia Boccaccio
- Instituto Leloir, Av. Patricias Argentinas 435, C1405BWE Buenos Aires, Argentina
- IIBBA-CONICET, C1405BWE Buenos Aires, Argentina
- Facultad de Ciencias Exactas y Naturales, University of Buenos Aires, Buenos Aires, Argentina
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Fiszer A, Krzyzosiak WJ. Oligonucleotide-based strategies to combat polyglutamine diseases. Nucleic Acids Res 2014; 42:6787-810. [PMID: 24848018 PMCID: PMC4066792 DOI: 10.1093/nar/gku385] [Citation(s) in RCA: 42] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023] Open
Abstract
Considerable advances have been recently made in understanding the molecular aspects of pathogenesis and in developing therapeutic approaches for polyglutamine (polyQ) diseases. Studies on pathogenic mechanisms have extended our knowledge of mutant protein toxicity, confirmed the toxicity of mutant transcript and identified other toxic RNA and protein entities. One very promising therapeutic strategy is targeting the causative gene expression with oligonucleotide (ON) based tools. This straightforward approach aimed at halting the early steps in the cascade of pathogenic events has been widely tested for Huntington's disease and spinocerebellar ataxia type 3. In this review, we gather information on the use of antisense oligonucleotides and RNA interference triggers for the experimental treatment of polyQ diseases in cellular and animal models. We present studies testing non-allele-selective and allele-selective gene silencing strategies. The latter include targeting SNP variants associated with mutations or targeting the pathologically expanded CAG repeat directly. We compare gene silencing effectors of various types in a number of aspects, including their design, efficiency in cell culture experiments and pre-clinical testing. We discuss advantages, current limitations and perspectives of various ON-based strategies used to treat polyQ diseases.
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Affiliation(s)
- Agnieszka Fiszer
- Department of Molecular Biomedicine, Institute of Bioorganic Chemistry, Polish Academy of Sciences, Noskowskiego 12/14, 61-704 Poznan, Poland
| | - Wlodzimierz J Krzyzosiak
- Department of Molecular Biomedicine, Institute of Bioorganic Chemistry, Polish Academy of Sciences, Noskowskiego 12/14, 61-704 Poznan, Poland
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Hoss AG, Kartha VK, Dong X, Latourelle JC, Dumitriu A, Hadzi TC, MacDonald ME, Gusella JF, Akbarian S, Chen JF, Weng Z, Myers RH. MicroRNAs located in the Hox gene clusters are implicated in huntington's disease pathogenesis. PLoS Genet 2014; 10:e1004188. [PMID: 24586208 PMCID: PMC3937267 DOI: 10.1371/journal.pgen.1004188] [Citation(s) in RCA: 84] [Impact Index Per Article: 8.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/14/2013] [Accepted: 01/06/2014] [Indexed: 12/12/2022] Open
Abstract
Transcriptional dysregulation has long been recognized as central to the pathogenesis of Huntington's disease (HD). MicroRNAs (miRNAs) represent a major system of post-transcriptional regulation, by either preventing translational initiation or by targeting transcripts for storage or for degradation. Using next-generation miRNA sequencing in prefrontal cortex (Brodmann Area 9) of twelve HD and nine controls, we identified five miRNAs (miR-10b-5p, miR-196a-5p, miR-196b-5p, miR-615-3p and miR-1247-5p) up-regulated in HD at genome-wide significance (FDR q-value<0.05). Three of these, miR-196a-5p, miR-196b-5p and miR-615-3p, were expressed at near zero levels in control brains. Expression was verified for all five miRNAs using reverse transcription quantitative PCR and all but miR-1247-5p were replicated in an independent sample (8HD/8C). Ectopic miR-10b-5p expression in PC12 HTT-Q73 cells increased survival by MTT assay and cell viability staining suggesting increased expression may be a protective response. All of the miRNAs but miR-1247-5p are located in intergenic regions of Hox clusters. Total mRNA sequencing in the same samples identified fifteen of 55 genes within the Hox cluster gene regions as differentially expressed in HD, and the Hox genes immediately adjacent to the four Hox cluster miRNAs as up-regulated. Pathway analysis of mRNA targets of these miRNAs implicated functions for neuronal differentiation, neurite outgrowth, cell death and survival. In regression models among the HD brains, huntingtin CAG repeat size, onset age and age at death were independently found to be inversely related to miR-10b-5p levels. CAG repeat size and onset age were independently inversely related to miR-196a-5p, onset age was inversely related to miR-196b-5p and age at death was inversely related to miR-615-3p expression. These results suggest these Hox-related miRNAs may be involved in neuroprotective response in HD. Recently, miRNAs have shown promise as biomarkers for human diseases and given their relationship to disease expression, these miRNAs are biomarker candidates in HD.
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Affiliation(s)
- Andrew G. Hoss
- Department of Neurology, Boston University School of Medicine, Boston, Massachusetts, United States of America
- Graduate Program in Genetics and Genomics, Boston University School of Medicine, Boston, Massachusetts, United States of America
| | - Vinay K. Kartha
- Department of Neurology, Boston University School of Medicine, Boston, Massachusetts, United States of America
- Bioinformatics Program, Boston University, Boston, Massachusetts, United States of America
| | - Xianjun Dong
- Program in Bioinformatics and Integrative Biology, and Department of Biochemistry and Molecular Pharmacology, University of Massachusetts Medical School, Worcester, Massachusetts, United States of America
| | - Jeanne C. Latourelle
- Department of Neurology, Boston University School of Medicine, Boston, Massachusetts, United States of America
| | - Alexandra Dumitriu
- Department of Neurology, Boston University School of Medicine, Boston, Massachusetts, United States of America
| | - Tiffany C. Hadzi
- Department of Neurology, Boston University School of Medicine, Boston, Massachusetts, United States of America
| | - Marcy E. MacDonald
- Center for Human Genetic Research, Massachusetts General Hospital, Harvard Medical School, Boston, Massachusetts, United States of America
| | - James F. Gusella
- Center for Human Genetic Research, Massachusetts General Hospital, Harvard Medical School, Boston, Massachusetts, United States of America
| | - Schahram Akbarian
- Friedman Brain Institute, Department of Psychiatry, Mount Sinai School of Medicine, New York, New York, United States of America
| | - Jiang-Fan Chen
- Department of Neurology, Boston University School of Medicine, Boston, Massachusetts, United States of America
| | - Zhiping Weng
- Program in Bioinformatics and Integrative Biology, and Department of Biochemistry and Molecular Pharmacology, University of Massachusetts Medical School, Worcester, Massachusetts, United States of America
| | - Richard H. Myers
- Department of Neurology, Boston University School of Medicine, Boston, Massachusetts, United States of America
- Genome Science Institute, Boston University School of Medicine, Boston, Massachusetts, United States of America
- * E-mail:
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Maciotta S, Meregalli M, Torrente Y. The involvement of microRNAs in neurodegenerative diseases. Front Cell Neurosci 2013; 7:265. [PMID: 24391543 PMCID: PMC3867638 DOI: 10.3389/fncel.2013.00265] [Citation(s) in RCA: 168] [Impact Index Per Article: 15.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/27/2013] [Accepted: 12/03/2013] [Indexed: 12/12/2022] Open
Abstract
Neurodegenerative diseases (NDDs) originate from a loss of neurons in the central nervous system and are severely debilitating. The incidence of NDDs increases with age, and they are expected to become more common due to extended life expectancy. Because no cure is available, these diseases have become a major challenge in neurobiology. The increasing relevance of microRNAs (miRNAs) in biology has prompted investigation into their possible involvement in neurodegeneration in order to identify new therapeutic targets. The idea of using miRNAs as therapeutic targets is not far from realization, but important issues need to be addressed before moving into the clinics. Here, we review what is known about the involvement of miRNAs in the pathogenesis of NDDs. We also report the miRNA expression levels in peripheral tissues of patients affected by NDDs in order to evaluate their application as biomarkers of disease. Finally, discrepancies, innovations, and the effectiveness of collected data will be elucidated and discussed.
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Affiliation(s)
- Simona Maciotta
- Stem Cell Laboratory, Department of Pathophysiology and Transplantation, Centro Dino Ferrari, Università degli Studi di Milano, Fondazione IRCCS Cà Granda Ospedale Maggiore Policlinico Milan, Italy ; Diabetes Research Institute, University of Miami Miller School of Medicine Miami, FL, USA
| | - Mirella Meregalli
- Stem Cell Laboratory, Department of Pathophysiology and Transplantation, Centro Dino Ferrari, Università degli Studi di Milano, Fondazione IRCCS Cà Granda Ospedale Maggiore Policlinico Milan, Italy
| | - Yvan Torrente
- Stem Cell Laboratory, Department of Pathophysiology and Transplantation, Centro Dino Ferrari, Università degli Studi di Milano, Fondazione IRCCS Cà Granda Ospedale Maggiore Policlinico Milan, Italy
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70
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Martí E, Estivill X. Small non-coding RNAs add complexity to the RNA pathogenic mechanisms in trinucleotide repeat expansion diseases. Front Mol Neurosci 2013; 6:45. [PMID: 24348326 PMCID: PMC3848198 DOI: 10.3389/fnmol.2013.00045] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/12/2013] [Accepted: 11/12/2013] [Indexed: 12/02/2022] Open
Abstract
Trinucleotide-repeat expansion diseases (TREDs) are a group of inherited human genetic disorders normally involving late-onset neurological/neurodegenerative affectation. Trinucleotide-repeat expansions occur in coding and non-coding regions of unique genes that typically result in protein and RNA toxic gain of function, respectively. In polyglutamine (polyQ) disorders caused by an expanded CAG repeat in the coding region of specific genes, neuronal dysfunction has been traditionally linked to the long polyQ stretch. However, a number of evidences suggest a detrimental role of the expanded/mutant mRNA, which may contribute to cell function impairment. In this review we describe the mechanisms of RNA-induced toxicity in TREDs with special focus in small-non-coding RNA pathogenic mechanisms and we summarize and comment on translational approaches targeting the expanded trinucleotide-repeat for disease modifying therapies.
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Affiliation(s)
- Eulàlia Martí
- Genomics and Disease, Bioinformatics and Genomics Programme, Centre for Genomic Regulation Barcelona, Spain ; Universitat Pompeu Fabra Barcelona, Spain
| | - Xavier Estivill
- Genomics and Disease, Bioinformatics and Genomics Programme, Centre for Genomic Regulation Barcelona, Spain ; Universitat Pompeu Fabra Barcelona, Spain
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71
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Alteration in Autophagic-lysosomal Potential During Aging and Neurological Diseases: The microRNA Perspective. CURRENT PATHOBIOLOGY REPORTS 2013. [DOI: 10.1007/s40139-013-0031-x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/26/2022]
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72
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Ramaswami M, Taylor JP, Parker R. Altered ribostasis: RNA-protein granules in degenerative disorders. Cell 2013; 154:727-36. [PMID: 23953108 DOI: 10.1016/j.cell.2013.07.038] [Citation(s) in RCA: 475] [Impact Index Per Article: 43.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/01/2013] [Indexed: 12/12/2022]
Abstract
The molecular processes that contribute to degenerative diseases are not well understood. Recent observations suggest that some degenerative diseases are promoted by the accumulation of nuclear or cytoplasmic RNA-protein (RNP) aggregates, which can be related to endogenous RNP granules. RNP aggregates arise commonly in degenerative diseases because RNA-binding proteins commonly self-assemble, in part through prion-like domains, which can form self-propagating amyloids. RNP aggregates may be toxic due to multiple perturbations of posttranscriptional control, thereby disrupting the normal "ribostasis" of the cell. This suggests that understanding and modulating RNP assembly or clearance may be effective approaches to developing therapies for these diseases.
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Affiliation(s)
- Mani Ramaswami
- School of Genetics and Microbiology and School of Natural Sciences, Smurfit Institute of Genetics and Trinity College Institute of Neuroscience, Trinity College Dublin, Dublin 2, Ireland.
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73
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Moumné L, Betuing S, Caboche J. Multiple Aspects of Gene Dysregulation in Huntington's Disease. Front Neurol 2013; 4:127. [PMID: 24167500 PMCID: PMC3806340 DOI: 10.3389/fneur.2013.00127] [Citation(s) in RCA: 47] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/30/2013] [Accepted: 08/20/2013] [Indexed: 12/27/2022] Open
Abstract
Huntington’s Disease (HD) is a genetic neurodegenerative disease caused by a CAG expansion in the gene encoding Huntingtin (Htt). It is characterized by chorea, cognitive, and psychiatric disorders. The most affected brain region is the striatum, and the clinical symptoms are directly correlated to the rate of striatal degeneration. The wild-type Htt is a ubiquitous protein and its deletion is lethal. Mutated (expanded) Htt produces excitotoxicity, mitochondrial dysfunctions, axonal transport deficit, altered proteasome activity, and gene dysregulation. Transcriptional dysregulation occurs at early neuropathological stages in HD patients. Multiple genes are dysregulated, with overlaps of altered transcripts between mouse models of HD and patient brains. Nuclear localization of Exp-Htt interferes with transcription factors, co-activators, and proteins of the transcriptional machinery. Another key mechanism described so far, is an alteration of cytoplasmic retention of the transcriptional repressor REST, which is normally associated with wild-type Htt. As such, Exp-Htt causes alteration of transcription of multiple genes involved in neuronal survival, plasticity, signaling, and mitochondrial biogenesis and respiration. Besides these transcriptional dysregulations, Exp-Htt affects the chromatin structure through altered post-translational modifications (PTM) of histones and methylation of DNA. Multiple alterations of histone PTM are described, including acetylation, methylation, ubiquitylation, polyamination, and phosphorylation. Exp-Htt also affects the expression and regulation of non-coding microRNAs (miRNAs). First multiple neural miRNAs are controlled by REST, and dysregulated in HD, with concomitant de-repression of downstream mRNA targets. Second, Exp-Htt protein or RNA may also play a major role in the processing of miRNAs and hence pathogenesis. These pleiotropic effects of Exp-Htt on gene expression may represent seminal deleterious effects in the pathogenesis of HD.
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Affiliation(s)
- Lara Moumné
- Laboratoire de Physiopathologie des Maladies du Système Nerveux Central, Neuronal Signaling and Gene Regulation, CNRS-UMR7224, INSERM-UMS952, Université Pierre et Marie Curie-Paris 6 , Paris , France
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74
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Goodall EF, Heath PR, Bandmann O, Kirby J, Shaw PJ. Neuronal dark matter: the emerging role of microRNAs in neurodegeneration. Front Cell Neurosci 2013; 7:178. [PMID: 24133413 PMCID: PMC3794211 DOI: 10.3389/fncel.2013.00178] [Citation(s) in RCA: 139] [Impact Index Per Article: 12.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/29/2013] [Accepted: 09/21/2013] [Indexed: 12/17/2022] Open
Abstract
MicroRNAs (miRNAs) are small, abundant RNA molecules that constitute part of the cell's non-coding RNA “dark matter.” In recent years, the discovery of miRNAs has revolutionised the traditional view of gene expression and our understanding of miRNA biogenesis and function has expanded. Altered expression of miRNAs is increasingly recognized as a feature of many disease states, including neurodegeneration. Here, we review the emerging role for miRNA dysfunction in Alzheimer's disease, Parkinson's disease, amyotrophic lateral sclerosis (ALS) and Huntington's disease pathogenesis. We emphasize the complex nature of gene regulatory networks and the need for systematic studies, with larger sample cohorts than have so far been reported, to reveal the most important miRNA regulators in disease. Finally, miRNA diversity and their potential to target multiple pathways, offers novel clinical applications for miRNAs as biomarkers and therapeutic agents in neurodegenerative diseases.
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Affiliation(s)
- Emily F Goodall
- Department of Neuroscience, Sheffield Institute for Translational Neuroscience, University of Sheffield Sheffield, UK
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75
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An SNP in the trinucleotide repeat region of the TNRC6A gene maps to a major TNGW1 autoepitope in patients with autoantibodies to GW182. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2013; 768:243-59. [PMID: 23224974 DOI: 10.1007/978-1-4614-5107-5_14] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
Abstract
GW/P bodies contain two TNRC6A protein isoforms (GW182 and TNGW1) that function as translational repressors of mRNA through Ago2-mediated RNA silencing. Autoantibodies to GW/P body components GW182, Ge-1 and Ago2 have previously been correlated with clinical autoimmune diseases including neurological disease, Sjögren's syndrome, systemic lupus erythematosus, rheumatoid arthritis and primary biliary cirrhosis. No studies were published to date examining if patients with autoantibodies directed against GW/P bodies contain autoantibodies to the trinucleotide repeat (TNR) region of TNGW1, which differs from GW182 only by the addition of an N-terminal QP-rich 253 amino acid sequence. Our data show that 85.7% of GW/P body positive plasma contain autoantibodies to various epitopes in the TNR region of TNGW1. Given the association of neurological diseases with autoantibodies directed to the TNR region on exon 5 of TNRC6A, this study examined whether there were TNR expansions as described in other neurological diseases and/or mutations in the nucleotide sequence of the CAG/CCA/G-rich region in seven anti-GW/P body positive patients, six control and eight breast cancer patients. Although a TNR expansion was not identified, 28.6% of patients containing autoantibodies to the TNR of TNGW1 were shown to have a single nucleotide polymorphism (SNP) at c.344C > A in the CAG/CCA/G-rich region of TNRC6A, which when translated, would produce a protein variant of p.Pro115Gln. The amino acid change may alter the structure of TNGW1 and/or perturb its miRNA regulatory function although this has not been examined experimentally. A putative change in protein structure may lead to a loss of tolerance to the TNGW1 protein or result in a "neo-antigen" in patients containing the specific TNRC6A SNPs. Further studies of a larger cohort of GW/P body positive patients and structure-function relationships of the variant TNRC6A are required to fully understand the role that such SNPs play in GW/P body autoantibody production and/or pathogenesis of related autoimmune diseases.
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76
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MicroRNA-22 (miR-22) overexpression is neuroprotective via general anti-apoptotic effects and may also target specific Huntington's disease-related mechanisms. PLoS One 2013; 8:e54222. [PMID: 23349832 PMCID: PMC3547907 DOI: 10.1371/journal.pone.0054222] [Citation(s) in RCA: 126] [Impact Index Per Article: 11.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/17/2012] [Accepted: 12/10/2012] [Indexed: 11/19/2022] Open
Abstract
Background Whereas many causes and mechanisms of neurodegenerative diseases have been identified, very few therapeutic strategies have emerged in parallel. One possible explanation is that successful treatment strategy may require simultaneous targeting of more than one molecule of pathway. A new therapeutic approach to have emerged recently is the engagement of microRNAs (miRNAs), which affords the opportunity to target multiple cellular pathways simultaneously using a single sequence. Methodology/Principal Findings We identified miR-22 as a potentially neuroprotective miRNA based on its predicted regulation of several targets implicated in Huntington’s disease (histone deacetylase 4 (HDAC4), REST corepresor 1 (Rcor1) and regulator of G-protein signaling 2 (Rgs2)) and its diminished expression in Huntington’s and Alzheimer’s disease brains. We then tested the hypothesis that increasing cellular levels of miRNA-22 would achieve neuroprotection in in vitro models of neurodegeneration. As predicted, overexpression of miR-22 inhibited neurodegeneration in primary striatal and cortical cultures exposed to a mutated human huntingtin fragment (Htt171-82Q). Overexpression of miR-22 also decreased neurodegeneration in primary neuronal cultures exposed to 3-nitropropionic acid (3-NP), a mitochondrial complex II/III inhibitor. In addition, miR-22 improved neuronal viability in an in vitro model of brain aging. The mechanisms underlying the effects of miR-22 included a reduction in caspase activation, consistent with miR-22′s targeting the pro-apoptotic activities of mitogen-activated protein kinase 14/p38 (MAPK14/p38) and tumor protein p53-inducible nuclear protein 1 (Tp53inp1). Moreover, HD-specific effects comprised not only targeting HDAC4, Rcor1 and Rgs2 mRNAs, but also decreasing focal accumulation of mutant Htt-positive foci, which occurred via an unknown mechanism. Conclusions These data show that miR-22 has multipartite anti-neurodegenerative activities including the inhibition of apoptosis and the targeting of mRNAs implicated in the etiology of HD. These results motivate additional studies to evaluate the feasibility and therapeutic efficacy of manipulating miR-22 in vivo.
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The discovery and analysis of P Bodies. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2013; 768:23-43. [PMID: 23224963 DOI: 10.1007/978-1-4614-5107-5_3] [Citation(s) in RCA: 70] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
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78
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Ma B, Tanese N. Combined FISH and immunofluorescent staining methods to co-localize proteins and mRNA in neurons and brain tissue. Methods Mol Biol 2013; 1010:123-38. [PMID: 23754223 DOI: 10.1007/978-1-62703-411-1_9] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/16/2023]
Abstract
Combining multicolor fluorescent in situ hybridization (FISH) and immunofluorescent staining (IFS) presents a powerful method for visualizing the spatial relationship between mRNA and proteins in different neural compartments. Although seemingly straightforward, the combination of IFS/FISH and quantitative co-localization analysis of mRNA and proteins can be difficult to perform successfully, often generating variable results. Here we describe a combined method of multicolor IFS and FISH in concert with two-dimensional (2D) and three-dimensional (3D) co-localization analysis for determining the expression of individual molecules in rat neurons and brain sections. Using this approach, we have analyzed interactions of the Huntington's disease protein huntingtin with select proteins and mRNA.
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Affiliation(s)
- Bin Ma
- Department of Microbiology, New York University School of Medicine, New York, NY, USA
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79
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Giacomello M, Oliveros JC, Naranjo JR, Carafoli E. Neuronal Ca(2+) dyshomeostasis in Huntington disease. Prion 2013; 7:76-84. [PMID: 23324594 DOI: 10.4161/pri.23581] [Citation(s) in RCA: 40] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022] Open
Abstract
The expansion of the N-terminal poly-glutamine tract of the huntingtin (Htt) protein is responsible for Huntington disease (HD). A large number of studies have explored the neuronal phenotype of HD, but the molecular aethiology of the disease is still very poorly understood. This has hampered the development of an appropriate therapeutical strategy to at least alleviate its symptoms. In this short review, we have focused our attention on the alteration of a specific cellular mechanism common to all HD models, either genetic or induced by treatment with 3-NPA, i.e. the cellular dyshomeostasis of Ca(2+). We have highlighted the direct and indirect (i.e. transcriptionally mediated) effects of mutated Htt on the maintenance of the intracellular Ca(2+) balance, the correct modulation of which is fundamental to cell survival and the disturbance of which plays a key role in the death of the cell.
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80
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Leung AKL, Sharp PA. Quantifying Argonaute proteins in and out of GW/P-bodies: implications in microRNA activities. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2013; 768:165-82. [PMID: 23224970 DOI: 10.1007/978-1-4614-5107-5_10] [Citation(s) in RCA: 37] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/04/2022]
Abstract
MicroRNAs (miRNAs) are a class of ∼22nt non-coding RNAs that regulate the translational potential and stability of mRNAs. Though constituting only 1-4% of human genes, miRNAs are predicted to regulate more than 60% of all mRNAs. The action of miRNAs is mediated through their associations with Argonaute proteins and mRNA targets. Previous studies indicated that though the majority of Argonaute proteins is diffusely distributed in the cytoplasm, a small fraction is consistently observed to be concentrated in a cytoplasmic compartment called GW/P-bodies. In this chapter, we will provide a quantitative and dynamic view of the subcellular localization of miRNA function, followed by a discussion on the possible roles of PBs in miRNA silencing.
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Affiliation(s)
- Anthony K L Leung
- Department of Biochemistry and Molecular Biology, Johns Hopkins University, Baltimore, MD 21205, USA.
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81
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Swanger SA, Bassell GJ. Dendritic protein synthesis in the normal and diseased brain. Neuroscience 2012; 232:106-27. [PMID: 23262237 DOI: 10.1016/j.neuroscience.2012.12.003] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/11/2012] [Revised: 11/21/2012] [Accepted: 12/01/2012] [Indexed: 01/25/2023]
Abstract
Synaptic activity is a spatially limited process that requires a precise, yet dynamic, complement of proteins within the synaptic micro-domain. The maintenance and regulation of these synaptic proteins is regulated, in part, by local mRNA translation in dendrites. Protein synthesis within the postsynaptic compartment allows neurons tight spatial and temporal control of synaptic protein expression, which is critical for proper functioning of synapses and neural circuits. In this review, we discuss the identity of proteins synthesized within dendrites, the receptor-mediated mechanisms regulating their synthesis, and the possible roles for these locally synthesized proteins. We also explore how our current understanding of dendritic protein synthesis in the hippocampus can be applied to new brain regions and to understanding the pathological mechanisms underlying varied neurological diseases.
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Affiliation(s)
- S A Swanger
- Department of Cell Biology, Emory University School of Medicine, Atlanta, GA 30322, USA
| | - G J Bassell
- Department of Cell Biology, 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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MicroRNAs in Neurodegenerative Disorders. CURRENT GERIATRICS REPORTS 2012. [DOI: 10.1007/s13670-012-0030-5] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
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83
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Singh S, Singh PK, Bhadauriya P, Ganesh S. Lafora disease E3 ubiquitin ligase malin is recruited to the processing bodies and regulates the microRNA-mediated gene silencing process via the decapping enzyme Dcp1a. RNA Biol 2012; 9:1440-9. [PMID: 23131811 DOI: 10.4161/rna.22708] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022] Open
Abstract
Intracellular transport, processing and stability of mRNA play critical roles in the functional physiology of the cell and defects in these processes are thought to underlie the pathogenesis in a number of neurodegenerative disorders. One of the cellular sites that regulate the mRNA half-life is the processing bodies, the dynamic cytoplasmic structures that represent the non-translating mRNA and the ribonucleoprotein complex that also control the decapping and translation of mRNA. In the present study we explored the possible role of malin E3 ubiquitin ligase in the mRNA decay pathway via the processing bodies. Defects in malin are associated with Lafora disease (LD)-a neurodegenerative disorder characterized by myoclonus seizures. We show here that malin is recruited to the processing bodies and that malin regulates the recruitment of mRNA decapping enzyme Dcp1a by promoting its degradation via the ubiquitin proteasome system. Depletion of malin results in elevated levels of Dcp1a and an altered microRNA-mediated gene silencing activity. Our study suggests that malin is one of the critical regulators of processing bodies and that defects in the mRNA processing might underlie some of the disease symptoms in LD.
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Affiliation(s)
- Sweta Singh
- Department of Biological Sciences and Bioengineering, Indian Institute of Technology, Kanpur, India
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84
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Abe M, Bonini NM. MicroRNAs and neurodegeneration: role and impact. Trends Cell Biol 2012; 23:30-6. [PMID: 23026030 DOI: 10.1016/j.tcb.2012.08.013] [Citation(s) in RCA: 160] [Impact Index Per Article: 13.3] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2012] [Revised: 08/30/2012] [Accepted: 08/31/2012] [Indexed: 10/27/2022]
Abstract
Neurodegenerative diseases are typically late-onset, progressive disorders that affect neural function and integrity. Although most attention has been focused on the genetic underpinnings of familial disease, mechanisms are likely to be shared with more predominant sporadic forms, which can be influenced by age, environment, and genetic inputs. Previous work has largely addressed the roles of select protein-coding genes; however, disease pathogenesis is complicated and can be modulated through not just protein-coding genes, but also regulatory mechanisms mediated by the exploding world of small non-coding RNAs. Here, we focus on emerging roles of miRNAs in age-associated events impacting long-term brain integrity and neurodegenerative disease.
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Affiliation(s)
- Masashi Abe
- Department of Biology, University of Pennsylvania, Philadelphia, PA 19104, USA
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85
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Abstract
MicroRNAs (miRNAs) represent a class of small regulatory noncoding RNAs ∼22 bp in length that mediate post-transcriptional silencing of gene expression via the recognition of specific sequences in target messenger (m)RNAs. The current body of literature suggests that miRNAs are fine-tuning regulators of gene expression profiles in a wide range of biological processes, from development to cancer. Many miRNAs are highly expressed in the adult nervous system in a spatially and temporally controlled manner in normal physiology, as well as in certain pathological conditions. These findings emphasize that gene regulation networks based on miRNA activities may be particularly important to brain function, and that perturbation of these networks may result in abnormal brain function. Indeed, miRNAs have been implicated in various aspects of dendrite remodeling and synaptic plasticity, as well as in experience-dependent adaptive changes of neural circuits in the postnatal developmental and adult brain. Recent advances in methods of next-generation sequencing, such as RNA-seq, offer the means to quantitatively evaluate the functions of miRNAs in a genome-wide manner in large cohorts of samples. These new technologies have already yielded valuable information and are expanding our understanding of miRNA-based mechanisms in higher-order brain processing, including learning and memory and cognition, as well as in neuropsychiatric disorders.
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Affiliation(s)
- Wenyuan Wang
- Picower Institute for Learning and Memory, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, USA
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86
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Ratovitski T, Chighladze E, Arbez N, Boronina T, Herbrich S, Cole RN, Ross CA. Huntingtin protein interactions altered by polyglutamine expansion as determined by quantitative proteomic analysis. Cell Cycle 2012; 11:2006-21. [PMID: 22580459 DOI: 10.4161/cc.20423] [Citation(s) in RCA: 89] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022] Open
Abstract
Huntington disease (HD) is a neurodegenerative disorder caused by an expansion of a polyglutamine repeat within the HD gene product, huntingtin. Huntingtin, a large (347 kDa) protein containing multiple HEAT repeats, acts as a scaffold for protein-protein interactions. Huntingtin-induced toxicity is believed to be mediated by a conformational change in expanded huntingtin, leading to protein misfolding and aggregation, aberrant protein interactions and neuronal cell death. While many non-systematic studies of huntingtin interactions have been reported, they were not designed to identify and quantify the changes in the huntingtin interactome induced by polyglutamine expansion. We used tandem affinity purification and quantitative proteomics to compare and quantify interactions of normal or expanded huntingtin isolated from a striatal cell line. We found that proteins preferentially interacting with expanded huntingtin are enriched for intrinsically disordered proteins, consistent with previously suggested roles of such proteins in neurodegenerative disorders. Our functional analysis indicates that proteins related to energy production, protein trafficking, RNA post-transcriptional modifications and cell death were significantly enriched among preferential interactors of expanded huntingtin. Expanded huntingtin interacted with many mitochondrial proteins, including AIFM1, consistent with a role for mitochondrial dysfunction in HD. Furthermore, expanded huntingtin interacted with the stress granule-associated proteins Caprin-1 and G3BP and redistributed to RNA stress granules under ER-stress conditions. These data demonstrate that a number of key cellular functions and networks may be disrupted by abnormal interactions of expanded huntingtin and highlight proteins and pathways that may be involved in HD cellular pathogenesis and that may serve as therapeutic targets.
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Affiliation(s)
- Tamara Ratovitski
- Division of Neurobiology, Department of Psychiatry, Johns Hopkins University School of Medicine, Baltimore, MD, USA.
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87
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Sinha M, Mukhopadhyay S, Bhattacharyya NP. Mechanism(s) of alteration of micro RNA expressions in Huntington's disease and their possible contributions to the observed cellular and molecular dysfunctions in the disease. Neuromolecular Med 2012; 14:221-43. [PMID: 22581158 DOI: 10.1007/s12017-012-8183-0] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/17/2011] [Accepted: 04/24/2012] [Indexed: 12/27/2022]
Abstract
To identify the mechanism of deregulation of micro RNAs (miRNAs) altered in Huntington's disease (HD) and their possible contributions to the altered cellular and molecular functions observed in the disease, we analyzed the altered miRNAs in the postmortem brains of HD patients. There are 54 miRNAs differentially expressed in HD brains of which 30 are upregulated and 24 downregulated. Some of these miRNAs were also altered in various models of the disease. Regulation of these miRNAs was attributed to transcription factors and the host genes to which these miRNAs reside. We observed that transcription regulators TP53, E2F1, REST, and GATA4 together could regulate expressions of 26 miRNAs in HD. Altered expressions of 13 intronic miRNAs were correlated with the expressions of their host genes. From literature, we further collected 287 experimentally validated targets of miRNAs upregulated in HD, while 304 validated targets of downregulated miRNAs in HD. Analysis of these validated target genes of altered miRNAs by gene ontology (GO) revealed that these genes are significantly enriched in GO terms belonging to (1) apoptosis, (2) differentiation and development, (3) fatty acid, cholesterol, lipid, glucose, and carbohydrate metabolism, (4) cell cycle and growth, and (5) transcription regulation. Experimental evidences that these processes are altered in HD are provided from published reports. In conclusion, altered miRNAs in HD might target many genes and may contribute to the altered cellular and molecular functions observed in HD.
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Affiliation(s)
- Mithun Sinha
- Structural Genomics Division, Saha Institute of Nuclear Physics, 1/AF Bidhan Nagar, Kolkata, 700 064, India
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88
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Culver BP, Savas JN, Park SK, Choi JH, Zheng S, Zeitlin SO, Yates JR, Tanese N. Proteomic analysis of wild-type and mutant huntingtin-associated proteins in mouse brains identifies unique interactions and involvement in protein synthesis. J Biol Chem 2012; 287:21599-614. [PMID: 22556411 DOI: 10.1074/jbc.m112.359307] [Citation(s) in RCA: 94] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Huntington disease is a neurodegenerative disorder caused by a CAG repeat amplification in the gene huntingtin (HTT) that is reflected by a polyglutamine expansion in the Htt protein. Nearly 20 years of research have uncovered roles for Htt in a wide range of cellular processes, and many of these discoveries stemmed from the identification of Htt-interacting proteins. However, no study has employed an impartial and comprehensive strategy to identify proteins that differentially associate with full-length wild-type and mutant Htt in brain tissue, the most relevant sample source to the disease condition. We analyzed Htt affinity-purified complexes from wild-type and HTT mutant juvenile mouse brain from two different biochemical fractions by tandem mass spectrometry. We compared variations in protein spectral counts relative to Htt to identify those proteins that are the most significantly contrasted between wild-type and mutant Htt purifications. Previously unreported Htt interactions with Myo5a, Prkra (PACT), Gnb2l1 (RACK1), Rps6, and Syt2 were confirmed by Western blot analysis. Gene Ontology analysis of these and other Htt-associated proteins revealed a statistically significant enrichment for proteins involved in translation among other categories. Furthermore, Htt co-sedimentation with polysomes in cytoplasmic mouse brain extracts is dependent upon the presence of intact ribosomes. Finally, wild-type or mutant Htt overexpression inhibits cap-dependent translation of a reporter mRNA in an in vitro system. Cumulatively, these data support a new role for Htt in translation and provide impetus for further study into the link between protein synthesis and Huntington disease pathogenesis.
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Affiliation(s)
- Brady P Culver
- Department of Microbiology, New York University School of Medicine, New York, New York 10016, USA
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89
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Gascon E, Gao FB. Cause or Effect: Misregulation of microRNA Pathways in Neurodegeneration. Front Neurosci 2012; 6:48. [PMID: 22509148 PMCID: PMC3321503 DOI: 10.3389/fnins.2012.00048] [Citation(s) in RCA: 67] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/13/2012] [Accepted: 03/23/2012] [Indexed: 12/12/2022] Open
Abstract
During normal aging or neurodegenerative diseases, neuronal survival and function depend on protein homeostasis, which is regulated by multiple mechanisms, including the microRNA (miRNA) pathway. In different cells types, the absence of Dicer, a key miRNA processing enzyme, leads to neurodegeneration through cell-autonomous and non-cell-autonomous mechanisms. Loss of certain miRNAs also causes neurodegeneration in some model organisms. On the other hand, miRNA expression is misregulated in patients with different neurodegenerative diseases. Thus, the miRNA pathway appears to be essential in the pathogenesis of several age-dependent neurodegenerative conditions; however, our understanding of the underlying mechanism remains rudimentary. The precise causal relationships between specific miRNAs and neurodegeneration in humans need to be further investigated.
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Affiliation(s)
- Eduardo Gascon
- Department of Neurology, University of Massachusetts Medical School Worcester, MA, USA
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90
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Human prion protein binds Argonaute and promotes accumulation of microRNA effector complexes. Nat Struct Mol Biol 2012; 19:517-24, S1. [PMID: 22484317 DOI: 10.1038/nsmb.2273] [Citation(s) in RCA: 40] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/05/2011] [Accepted: 02/28/2012] [Indexed: 12/13/2022]
Abstract
Despite intense research in the context of neurodegenerative diseases associated with its misfolding, the endogenous human prion protein PrP(C) (or PRNP) has poorly understood physiological functions. Whereas most PrP(C) is exposed to the extracellular environment, conserved domains result in transmembrane forms of PrP(C) that traffic in the endolysosomal system and are linked to inherited and infectious neuropathologies. One transmembrane PrP(C) variant orients the N-terminal 'octarepeat' domain into the cytoplasm. Here we demonstrate that the octarepeat domain of human PrP(C) contains GW/WG motifs that bind Argonaute (AGO) proteins, the essential components of microRNA (miRNA)-induced silencing complexes (miRISCs). Transmembrane PrP(C) preferentially binds AGO, and PrP(C) promotes formation or stability of miRISC effector complexes containing the trinucleotide repeat-containing gene 6 proteins (TNRC6) and miRNA-repressed mRNA. Accordingly, effective repression of several miRNA targets requires PrP(C). We propose that dynamic interactions between PrP(C)-enriched endosomes and subcellular foci of AGO underpin these effects.
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91
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A pathogenic mechanism in Huntington's disease involves small CAG-repeated RNAs with neurotoxic activity. PLoS Genet 2012; 8:e1002481. [PMID: 22383888 PMCID: PMC3285580 DOI: 10.1371/journal.pgen.1002481] [Citation(s) in RCA: 134] [Impact Index Per Article: 11.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/19/2011] [Accepted: 11/24/2011] [Indexed: 11/19/2022] Open
Abstract
Huntington's disease (HD) is an autosomal dominantly inherited disorder caused by the expansion of CAG repeats in the Huntingtin (HTT) gene. The abnormally extended polyglutamine in the HTT protein encoded by the CAG repeats has toxic effects. Here, we provide evidence to support that the mutant HTT CAG repeats interfere with cell viability at the RNA level. In human neuronal cells, expanded HTT exon-1 mRNA with CAG repeat lengths above the threshold for complete penetrance (40 or greater) induced cell death and increased levels of small CAG-repeated RNAs (sCAGs), of ≈21 nucleotides in a Dicer-dependent manner. The severity of the toxic effect of HTT mRNA and sCAG generation correlated with CAG expansion length. Small RNAs obtained from cells expressing mutant HTT and from HD human brains significantly decreased neuronal viability, in an Ago2-dependent mechanism. In both cases, the use of anti-miRs specific for sCAGs efficiently blocked the toxic effect, supporting a key role of sCAGs in HTT-mediated toxicity. Luciferase-reporter assays showed that expanded HTT silences the expression of CTG-containing genes that are down-regulated in HD. These results suggest a possible link between HD and sCAG expression with an aberrant activation of the siRNA/miRNA gene silencing machinery, which may trigger a detrimental response. The identification of the specific cellular processes affected by sCAGs may provide insights into the pathogenic mechanisms underlying HD, offering opportunities to develop new therapeutic approaches. Huntington's disease (HD) is a neurodegenerative disorder caused by an abnormal CAG expansion in the Huntingtin gene (HTT), resulting in an expanded polyglutamine track in the HTT protein. Longer CAG expansions correlate with an earlier more severe manifestation of the disease that produces choreic movement, behavioural and psychiatric disturbances, and dementia. Although the causative gene is widely expressed, neuropathology is characterized by striatal and cortical atrophy. HTT interacts with proteins involved in transcription, cell signaling, and transport. The pathogenic role of mutant HTT is not fully understood. This study shows that CAG expanded HTT RNA also contributes to neuronal toxicity. Mutant HTT RNA gives rise to small CAG-repeated RNAs (sCAGs) with neurotoxic activity. These short RNAs interfere with cell functions by silencing the expression of genes that are fully or partially complementary, through a mechanism similar to that of microRNAs. These findings suggest that a small RNA–dependent mechanism may contribute to HD neuronal cell loss. The exhaustive identification of the target genes modulated by sCAGs may lead to a better understanding of HD pathology, allowing the development of new therapeutic strategies.
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92
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Baez MV, Luchelli L, Maschi D, Habif M, Pascual M, Thomas MG, Boccaccio GL. Smaug1 mRNA-silencing foci respond to NMDA and modulate synapse formation. ACTA ACUST UNITED AC 2012; 195:1141-57. [PMID: 22201125 PMCID: PMC3246892 DOI: 10.1083/jcb.201108159] [Citation(s) in RCA: 43] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
S-foci, the first reported mRNA-silencing foci specific to neurons, may control local mRNA translation in response to NMDA receptor stimulation and synaptic plasticity. Mammalian Smaug1/Samd4A is a translational repressor. Here we show that Smaug1 forms mRNA-silencing foci located at postsynapses of hippocampal neurons. These structures, which we have named S-foci, are distinct from P-bodies, stress granules, or other neuronal RNA granules hitherto described, and are the first described mRNA-silencing foci specific to neurons. RNA binding was not required for aggregation, which indicates that S-foci formation is not a consequence of mRNA silencing. N-methyl-d-aspartic acid (NMDA) receptor stimulation provoked a rapid and reversible disassembly of S-foci, transiently releasing transcripts (the CaMKIIα mRNA among others) to allow their translation. Simultaneously, NMDA triggered global translational silencing, which suggests the specific activation of Smaug1-repressed transcripts. Smaug1 is expressed during synaptogenesis, and Smaug1 knockdown affected the number and size of synapses, and also provoked an impaired response to repetitive depolarizing stimuli, as indicated by a reduced induction of Arc/Arg3.1. Our results suggest that S-foci control local translation, specifically responding to NMDA receptor stimulation and affecting synaptic plasticity.
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93
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Tan H, Xu Z, Jin P. Role of noncoding RNAs in trinucleotide repeat neurodegenerative disorders. Exp Neurol 2012; 235:469-75. [PMID: 22309832 DOI: 10.1016/j.expneurol.2012.01.019] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/10/2011] [Revised: 01/11/2012] [Accepted: 01/19/2012] [Indexed: 11/25/2022]
Abstract
Increasingly complex networks of noncoding RNAs are being found to play important and diverse roles in the regulation of gene expression throughout the genome. Many lines of evidence are linking mutations and dysregulations of noncoding RNAs to a host of human diseases, and noncoding RNAs have been implicated in the molecular pathogenesis of some neurodegenerative disorders. The expansion of trinucleotide repeats is now recognized as a major cause of neurological disorders. Here we will review our current knowledge of the proposed mechanisms behind the involvement of noncoding RNAs in the molecular pathogenesis of neurodegenerative disorders, particularly the sequestration of specific RNA-binding proteins, the regulation of antisense transcripts, and the role of the microRNA pathway in the context of known neurodegenerative disorders caused by the expansion of trinucleotide repeats.
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Affiliation(s)
- Huiping Tan
- Department of Human Genetics, Emory University School of Medicine, Atlanta, GA 30322, USA
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94
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Seredenina T, Luthi-Carter R. What have we learned from gene expression profiles in Huntington's disease? Neurobiol Dis 2012; 45:83-98. [DOI: 10.1016/j.nbd.2011.07.001] [Citation(s) in RCA: 112] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/16/2011] [Revised: 06/24/2011] [Accepted: 07/01/2011] [Indexed: 12/22/2022] Open
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95
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Ma B, Savas JN, Yu MS, Culver BP, Chao MV, Tanese N. Huntingtin mediates dendritic transport of β-actin mRNA in rat neurons. Sci Rep 2011; 1:140. [PMID: 22355657 PMCID: PMC3216621 DOI: 10.1038/srep00140] [Citation(s) in RCA: 46] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/16/2011] [Accepted: 10/18/2011] [Indexed: 12/30/2022] Open
Abstract
Transport of mRNAs to diverse neuronal locations via RNA granules serves an important function in regulating protein synthesis within restricted sub-cellular domains. We recently detected the Huntington's disease protein huntingtin (Htt) in dendritic RNA granules; however, the functional significance of this localization is not known. Here we report that Htt and the huntingtin-associated protein 1 (HAP1) are co-localized with the microtubule motor proteins, the KIF5A kinesin and dynein, during dendritic transport of β-actin mRNA. Live cell imaging demonstrated that β-actin mRNA is associated with Htt, HAP1, and dynein intermediate chain in cultured neurons. Reduction in the levels of Htt, HAP1, KIF5A, and dynein heavy chain by lentiviral-based shRNAs resulted in a reduction in the transport of β-actin mRNA. These findings support a role for Htt in participating in the mRNA transport machinery that also contains HAP1, KIF5A, and dynein.
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Affiliation(s)
- Bin Ma
- Department of Microbiology, New York University School of Medicine, 550 First Ave., New York, NY 10016, USA; Institute of Pathology, University Medical Center, Johannes Gutenberg University, Langenbeckstrasse 1, D-55101 Mainz, Germany
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96
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Abstract
Recent experiments on nucleoli suggest that their dynamic behavior is liquid-like with common fusion events and that the surrounding actin plays an active role in these dynamics.
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97
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Zheng D, Chen CYA, Shyu AB. Unraveling regulation and new components of human P-bodies through a protein interaction framework and experimental validation. RNA (NEW YORK, N.Y.) 2011; 17:1619-34. [PMID: 21750099 PMCID: PMC3162328 DOI: 10.1261/rna.2789611] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/18/2023]
Abstract
The cellular factors involved in mRNA degradation and translation repression can aggregate into cytoplasmic domains known as GW bodies or mRNA processing bodies (P-bodies). However, current understanding of P-bodies, especially the regulatory aspect, remains relatively fragmentary. To provide a framework for studying the mechanisms and regulation of P-body formation, maintenance, and disassembly, we compiled a list of P-body proteins found in various species and further grouped both reported and predicted human P-body proteins according to their functions. By analyzing protein-protein interactions of human P-body components, we found that many P-body proteins form complex interaction networks with each other and with other cellular proteins that are not recognized as P-body components. The observation suggests that these other cellular proteins may play important roles in regulating P-body dynamics and functions. We further used siRNA-mediated gene knockdown and immunofluorescence microscopy to demonstrate the validity of our in silico analyses. Our combined approach identifies new P-body components and suggests that protein ubiquitination and protein phosphorylation involving 14-3-3 proteins may play critical roles for post-translational modifications of P-body components in regulating P-body dynamics. Our analyses provide not only a global view of human P-body components and their physical interactions but also a wealth of hypotheses to help guide future research on the regulation and function of human P-bodies.
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Affiliation(s)
- Dinghai Zheng
- Department of Biochemistry and Molecular Biology, The University of Texas Medical School, Houston, Texas 77021, USA
| | - Chyi-Ying A. Chen
- Department of Biochemistry and Molecular Biology, The University of Texas Medical School, Houston, Texas 77021, USA
| | - Ann-Bin Shyu
- Department of Biochemistry and Molecular Biology, The University of Texas Medical School, Houston, Texas 77021, USA
- Corresponding author.E-mail .
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98
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Maes OC, Chertkow HM, Wang E, Schipper HM. MicroRNA: Implications for Alzheimer Disease and other Human CNS Disorders. Curr Genomics 2011; 10:154-68. [PMID: 19881909 PMCID: PMC2705849 DOI: 10.2174/138920209788185252] [Citation(s) in RCA: 159] [Impact Index Per Article: 12.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/23/2009] [Revised: 02/18/2009] [Accepted: 03/11/2009] [Indexed: 02/06/2023] Open
Abstract
Understanding complex diseases such as sporadic Alzheimer disease (AD) has been a major challenge. Unlike the familial forms of AD, the genetic and environmental risks factors identified for sporadic AD are extensive. MicroRNAs are one of the major noncoding RNAs that function as negative regulators to silence or suppress gene expression via translational inhibition or message degradation. Their discovery has evoked great excitement in biomedical research for their promise as potential disease biomarkers and therapeutic targets. Key microRNAs have been identified as essential for a variety of cellular events including cell lineage determination, proliferation, apoptosis, DNA repair, and cytoskeletal organization; most, if not all, acting to fine-tune gene expression at the post-transcriptional level in a host of cellular signaling networks. Dysfunctional microRNA-mediated regulation has been implicated in the pathogenesis of many disease states. Here, the current understanding of the role of miRNAs in the central nervous system is reviewed with emphasis on their impact on the etiopathogenesis of sporadic AD.
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Affiliation(s)
- Olivier C Maes
- Bloomfield Centre for Research in Aging, Lady Davis Institute for Medical Research, Sir Mortimer B. Davis Jewish General Hospital, Montreal, Canada
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99
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Active liquid-like behavior of nucleoli determines their size and shape in Xenopus laevis oocytes. Proc Natl Acad Sci U S A 2011; 108:4334-9. [PMID: 21368180 DOI: 10.1073/pnas.1017150108] [Citation(s) in RCA: 860] [Impact Index Per Article: 66.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023] Open
Abstract
For most intracellular structures with larger than molecular dimensions, little is known about the connection between underlying molecular activities and higher order organization such as size and shape. Here, we show that both the size and shape of the amphibian oocyte nucleolus ultimately arise because nucleoli behave as liquid-like droplets of RNA and protein, exhibiting characteristic viscous fluid dynamics even on timescales of < 1 min. We use these dynamics to determine an apparent nucleolar viscosity, and we show that this viscosity is ATP-dependent, suggesting a role for active processes in fluidizing internal contents. Nucleolar surface tension and fluidity cause their restructuring into spherical droplets upon imposed mechanical deformations. Nucleoli exhibit a broad distribution of sizes with a characteristic power law, which we show is a consequence of spontaneous coalescence events. These results have implications for the function of nucleoli in ribosome subunit processing and provide a physical link between activity within a macromolecular assembly and its physical properties on larger length scales.
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100
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Abstract
It has been more than 17 years since the causative mutation for Huntington's disease was discovered as the expansion of the triplet repeat in the N-terminal portion of the Huntingtin (HTT) gene. In the intervening time, researchers have discovered a great deal about Huntingtin's involvement in a number of cellular processes. However, the role of Huntingtin in the key pathogenic mechanism leading to neurodegeneration in the disease process has yet to be discovered. Here, we review the body of knowledge that has been uncovered since gene discovery and include discussions of the HTT gene, CAG triplet repeat expansion, HTT expression, protein features, posttranslational modifications, and many of its known protein functions and interactions. We also highlight potential pathogenic mechanisms that have come to light in recent years.
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Affiliation(s)
- Karen N McFarland
- Department of Neurology, University of Florida, Gainesville, FL 32610-0236, USA.
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