1
|
Barnhart MD, Moon SL, Emch AW, Wilusz CJ, Wilusz J. Changes in cellular mRNA stability, splicing, and polyadenylation through HuR protein sequestration by a cytoplasmic RNA virus. Cell Rep 2013; 5:909-17. [PMID: 24210824 PMCID: PMC3849337 DOI: 10.1016/j.celrep.2013.10.012] [Citation(s) in RCA: 58] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/11/2013] [Revised: 09/13/2013] [Accepted: 10/07/2013] [Indexed: 12/12/2022] Open
Abstract
The impact of RNA viruses on the posttranscriptional regulation of cellular gene expression is unclear. Sindbis virus causes a dramatic relocalization of the cellular HuR protein from the nucleus to the cytoplasm in infected cells. This is to the result of the expression of large amounts of viral RNAs that contain high-affinity HuR binding sites in their 3' UTRs effectively serving as a sponge for the HuR protein. Sequestration of HuR by Sindbis virus is associated with destabilization of cellular mRNAs that normally bind HuR and rely on it to regulate their expression. Furthermore, significant changes can be observed in nuclear alternative polyadenylation and splicing events on cellular pre-mRNAs as a result of sequestration of HuR protein by the 3' UTR of transcripts of this cytoplasmic RNA virus. These studies suggest a molecular mechanism of virus-host interaction that probably has a significant impact on virus replication, cytopathology, and pathogenesis.
Collapse
Affiliation(s)
| | | | - Alexander W. Emch
- Cell and Molecular Biology Program, Department of Microbiology, Immunology and Pathology, Colorado State University, Fort Collins, CO 80525
| | - Carol J. Wilusz
- Cell and Molecular Biology Program, Department of Microbiology, Immunology and Pathology, Colorado State University, Fort Collins, CO 80525
| | - Jeffrey Wilusz
- Cell and Molecular Biology Program, Department of Microbiology, Immunology and Pathology, Colorado State University, Fort Collins, CO 80525
| |
Collapse
|
2
|
What's hAPPening at synapses? The role of amyloid β-protein precursor and β-amyloid in neurological disorders. Mol Psychiatry 2013; 18:425-34. [PMID: 22925831 DOI: 10.1038/mp.2012.122] [Citation(s) in RCA: 48] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/18/2023]
Abstract
Accumulating evidence suggests that dysregulated levels of amyloid β-protein precursor (APP) and its catabolites contribute to the impaired synaptic plasticity and seizure incidence observed in several neurological disorders, including Alzheimer's disease, fragile X syndrome, Down's syndrome, autism, epilepsy and Parkinson's disease as well as in brain injury. This review article summarizes what is known regarding the synaptic synthesis, processing and function of APP and amyloid-beta (Aβ), as well as discusses how these proteins could contribute to the altered synaptic plasticity and pathology of the aforementioned disorders. In addition, APP and its proteolytic fragments are emerging as biomarkers for neurological health, and pharmacological interventions that modulate their levels, such as secretase inhibitors, passive immunotherapy against Aβ and mGluR5 antagonists, are reviewed.
Collapse
|
3
|
Abstract
This is a review of RNA as a target for small molecules (ribosomes, riboswitches, regulatory RNAs) and RNA-derived oligonucleotides as tools (antisense/small interfering RNA, ribozymes, aptamers/decoy RNA and microRNA). This review highlights the present state of research using RNA as a drug target or as a potential drug candidate and explains at which stage and to what extent rational design could eventually be involved. Special attention has been paid to the recent potential clinical applications of RNA either as drugs or drug targets. The review deals mainly with mechanistic approaches rather than with physicochemical or computational aspects of RNA-based drug design.
Collapse
Affiliation(s)
- Irene M Lagoja
- Katholieke Universiteit Leuven, Laboratory of Medicinal Chemistry, Rega Institute for Medical Research, Minderbroedersstraat 10, B-3000 Leuven, Belgium +32 16 337396 ; +32 16 337340 ;
| | | |
Collapse
|
4
|
Westmark CJ, Malter JS. The regulation of AβPP expression by RNA-binding proteins. Ageing Res Rev 2012; 11:450-9. [PMID: 22504584 DOI: 10.1016/j.arr.2012.03.005] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/01/2011] [Revised: 03/13/2012] [Accepted: 03/28/2012] [Indexed: 12/29/2022]
Abstract
Amyloid β-protein precursor (AβPP) is cleaved by β- and γ-secretases to liberate amyloid beta (Aβ), the predominant protein found in the senile plaques associated with Alzheimer's disease (AD) and Down syndrome (Masters et al., 1985). Intense investigation by the scientific community has centered on understanding the molecular pathways that underlie the production and accumulation of Aβ Therapeutics that reduce the levels of this tenacious, plaque-promoting peptide may reduce the ongoing neural dysfunction and neuronal degeneration that occurs so profoundly in AD. AβPP and Aβ production are highly complex and involve still to be elucidated combinations of transcriptional, post-transcriptional, translational and post-translational events that mediate the production, processing and clearance of these proteins. Research in our laboratory for the past two decades has focused on the role of RNA binding proteins (RBPs) in mediating the post-transcriptional as well as translational regulation of APP messenger RNA (mRNA). This review article summarizes our findings, as well as those from other laboratories, describing the identification of regulatory RBPs, where and under what conditions they interact with APP mRNA and how those interactions control AβPP and Aβ synthesis.
Collapse
Affiliation(s)
- Cara J Westmark
- University of Wisconsin, Waisman Center for Developmental Disabilities, 1500 Highland Avenue, Madison, WI 53705, USA.
| | | |
Collapse
|
5
|
Long JM, Ray B, Lahiri DK. MicroRNA-153 physiologically inhibits expression of amyloid-β precursor protein in cultured human fetal brain cells and is dysregulated in a subset of Alzheimer disease patients. J Biol Chem 2012; 287:31298-310. [PMID: 22733824 DOI: 10.1074/jbc.m112.366336] [Citation(s) in RCA: 148] [Impact Index Per Article: 12.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022] Open
Abstract
Regulation of amyloid-β (Aβ) precursor protein (APP) expression is complex. MicroRNAs (miRNAs) are expected to participate in the molecular network that controls this process. The composition of this network is, however, still undefined. Elucidating the complement of miRNAs that regulate APP expression should reveal novel drug targets capable of modulating Aβ production in AD. Here, we investigated the contribution of miR-153 to this regulatory network. A miR-153 target site within the APP 3'-untranslated region (3'-UTR) was predicted by several bioinformatic algorithms. We found that miR-153 significantly reduced reporter expression when co-transfected with an APP 3'-UTR reporter construct. Mutation of the predicted miR-153 target site eliminated this reporter response. miR-153 delivery in both HeLa cells and primary human fetal brain cultures significantly reduced APP expression. Delivery of a miR-153 antisense inhibitor to human fetal brain cultures significantly elevated APP expression. miR-153 delivery also reduced expression of the APP paralog APLP2. High functional redundancy between APP and APLP2 suggests that miR-153 may target biological pathways in which they both function. Interestingly, in a subset of human AD brain specimens with moderate AD pathology, miR-153 levels were reduced. This same subset also exhibited elevated APP levels relative to control specimens. Therefore, endogenous miR-153 inhibits expression of APP in human neurons by specifically interacting with the APP 3'-UTR. This regulatory interaction may have relevance to AD etiology, where low miR-153 levels may drive increased APP expression in a subset of AD patients.
Collapse
Affiliation(s)
- Justin M Long
- Department of Psychiatry, Indiana University School of Medicine, Indianapolis, Indiana 46202, USA
| | | | | |
Collapse
|
6
|
Cheung CMG, Vania M, Ang M, Chee SP, Li J. Comparison of aqueous humor cytokine and chemokine levels in diabetic patients with and without retinopathy. Mol Vis 2012; 12:6. [PMID: 22475346 PMCID: PMC3733519 DOI: 10.1186/1471-2415-12-6] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/11/2011] [Accepted: 04/04/2012] [Indexed: 12/15/2022] Open
Abstract
Background Major-histocompatibility-complex class I-related chain A (MICA) antigens are
the ligands of NKG2D, which is an activating or coactivating receptor
expressed on human NK cells and CD8+T cells. We sought to
determine whether MICA expression in human corneal epithelium (HCE) could
affect the cytotoxicity mediated by NK cells or CD8+T cells. Methods Cell cultures of HCE were harvested from human donor eyes. Flow cytometric
analysis and ELISA was performed to determine the levels of MICA expression
on HCE. Then, HCE was transfected with a lentivirus vector expressing MICA
and GFP. Flow cytometric analysis, RT-PCR, western blot and ELISA were
performed to check the levels of MICA expression. For cytotoxicity testing,
allogeneic NK cells and CD8+T cells were isolated from peripheral
blood mononuclear cells of healthy volunteers by magnetic cell sorting. The
cytolytic activity of NK cells and CD8+T cells was assessed
against MICA-transfected HCE (NK cells: E:T ratio = 3:1;
CD8+T cells: E:T ratio = 10:1) using the
nonradioactive cytotoxicity detection kit lactate deshydrogenase. Results Surface expression of MICA on corneal epithelium was identified at a low
level. A cell line of stable human MICA-transfected corneal epithelium was
successfully established. Heightened expression of MICA on HCE was found to
promote the cytotoxicity mediated by NK cells or CD8+T cells,
which could be blocked by an anti-MICA antibody. Conclusion MICA molecules may contribute to cytotoxic responses mediated by activated
immune effector cells in corneal epithelium immunity.
Collapse
|
7
|
Bolognani F, Gallani AI, Sokol L, Baskin DS, Meisner-Kober N. mRNA stability alterations mediated by HuR are necessary to sustain the fast growth of glioma cells. J Neurooncol 2011; 106:531-42. [PMID: 21935689 DOI: 10.1007/s11060-011-0707-1] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/07/2010] [Accepted: 08/19/2011] [Indexed: 10/17/2022]
Abstract
Regulation of mRNA decay is an important mechanism controlling gene expression. Steady state levels of mRNAs can be markedly altered by changes in the decay rate. The control of mRNA stability depends on sequences in the transcript itself and on RNA-binding proteins that dynamically bind to these sequences. A well characterized sequence motif, which has been shown to be present in many short-lived mRNAs, is the de-stabilizing adenylate/uridylate-rich element (ARE) located at the 3' untranslated region (3'UTR) of mRNAs. HuR is an RNA-binding protein, which binds to AREs and in doing so, increases the half-life and steady state levels of the corresponding mRNA. Using tissue microarray technology, we found that HuR is over-expressed in human gliomas. We also found that there is a change in HuR localization from being solely in the nucleus to being expressed at high levels in the cytosol. Moreover, a positive correlation was found between total HuR levels, cytosolic localization and tumor grade. We also studied the decay rate of several HuR target mRNAs and found that these mRNAs have a slower rate of decay in glioma cell lines than in astrocytes. Finally, we have been able to decrease both the stability and steady state level of these transcripts in glioma cells using an RNA decoy. More importantly, the decoy transfected cells and cells exposed to a HuR inhibitor have reduced cell growth. In addition, pharmacological inhibition of HuR also resulted in glioma cell growth inhibition. In conclusion, our data suggest that post-transcriptional control abnormalities mediated by HuR are necessary to sustain the rapid growth of this devastating type of cancer.
Collapse
Affiliation(s)
- Federico Bolognani
- Department of Neurosurgery, The Methodist Hospital and The Methodist Hospital Research Institute, Houston, TX 77030, USA.
| | | | | | | | | |
Collapse
|
8
|
Ray B, Long JM, Sokol DK, Lahiri DK. Increased secreted amyloid precursor protein-α (sAPPα) in severe autism: proposal of a specific, anabolic pathway and putative biomarker. PLoS One 2011; 6:e20405. [PMID: 21731612 PMCID: PMC3120811 DOI: 10.1371/journal.pone.0020405] [Citation(s) in RCA: 87] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/13/2011] [Accepted: 04/23/2011] [Indexed: 12/11/2022] Open
Abstract
Autism is a neurodevelopmental disorder characterized by deficits in verbal communication, social interactions, and the presence of repetitive, stereotyped and compulsive behaviors. Excessive early brain growth is found commonly in some patients and may contribute to disease phenotype. Reports of increased levels of brain-derived neurotrophic factor (BDNF) and other neurotrophic-like factors in autistic neonates suggest that enhanced anabolic activity in CNS mediates this overgrowth effect. We have shown previously that in a subset of patients with severe autism and aggression, plasma levels of the secreted amyloid-β (Aβ) precursor protein-alpha form (sAPPα) were significantly elevated relative to controls and patients with mild-to-moderate autism. Here we further tested the hypothesis that levels of sAPPα and sAPPβ (proteolytic cleavage products of APP by α- and β-secretase, respectively) are deranged in autism and may contribute to an anabolic environment leading to brain overgrowth. We measured plasma levels of sAPPα, sAPPβ, Aβ peptides and BDNF by corresponding ELISA in a well characterized set of subjects. We included for analysis 18 control, 6 mild-to-moderate, and 15 severely autistic patient plasma samples. We have observed that sAPPα levels are increased and BDNF levels decreased in the plasma of patients with severe autism as compared to controls. Further, we show that Aβ1-40, Aβ1-42, and sAPPβ levels are significantly decreased in the plasma of patients with severe autism. These findings do not extend to patients with mild-to-moderate autism, providing a biochemical correlate of phenotypic severity. Taken together, this study provides evidence that sAPPα levels are generally elevated in severe autism and suggests that these patients may have aberrant non-amyloidogenic processing of APP.
Collapse
Affiliation(s)
- Balmiki Ray
- Department of Psychiatry, Institute of Psychiatric Research, Indiana University School of Medicine, Indianapolis, Indiana, United States of America
| | - Justin M. Long
- Department of Psychiatry, Institute of Psychiatric Research, Indiana University School of Medicine, Indianapolis, Indiana, United States of America
| | - Deborah K. Sokol
- Department of Neurology, Indiana University School of Medicine, Indianapolis, Indiana, United States of America
| | - Debomoy K. Lahiri
- Department of Psychiatry, Institute of Psychiatric Research, Indiana University School of Medicine, Indianapolis, Indiana, United States of America
- Department of Medical and Molecular Genetics, Indiana University School of Medicine, Indianapolis, Indiana, United States of America
| |
Collapse
|
9
|
Moncini S, Salvi A, Zuccotti P, Viero G, Quattrone A, Barlati S, De Petro G, Venturin M, Riva P. The role of miR-103 and miR-107 in regulation of CDK5R1 expression and in cellular migration. PLoS One 2011; 6:e20038. [PMID: 21625387 PMCID: PMC3100319 DOI: 10.1371/journal.pone.0020038] [Citation(s) in RCA: 81] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/26/2010] [Accepted: 04/24/2011] [Indexed: 11/26/2022] Open
Abstract
CDK5R1 encodes p35, a specific activator of the serine/threonine kinase CDK5, which plays crucial roles in CNS development and maintenance. CDK5 activity strongly depends on p35 levels and p35/CDK5 misregulation is deleterious for correct CNS function, suggesting that a tightly controlled regulation of CDK5R1 expression is needed for proper CDK5 activity. Accordingly, CDK5R1 expression was demonstrated to be controlled at both transcriptional and post-transcriptional levels, but a possible regulation through microRNAs (miRNAs) has never been investigated. We predicted, within the large CDK5R1 3′UTR several miRNA target sites. Among them, we selected for functional studies miR-103 and miR-107, whose expression has shown a strong inverse correlation with p35 levels in different cell lines. A significant reduction of CDK5R1 mRNA and p35 levels was observed after transfection of SK-N-BE neuroblastoma cells with the miR-103 or miR-107 precursor (pre-miR-103 or pre-miR-107). Conversely, p35 levels significantly increased following transfection of the corresponding antagonists (anti-miR-103 or anti-miR-107). Moreover, the level of CDK5R1 transcript shifts from the polysomal to the subpolysomal mRNA fraction after transfection with pre-miR-107 and, conversely, from the subpolysomal to the polysolmal mRNA fraction after transfection with anti-miR-107, suggesting a direct action on translation efficiency. We demonstrate, by means of luciferase assays, that miR-103 and miR-107 are able to directly interact with the CDK5R1 3′-UTR, in correspondence of a specific target site. Finally, miR-103 and miR-107 overexpression, as well as CDK5R1 silencing, caused a reduction in SK-N-BE migration ability, indicating that these miRNAs affect neuronal migration by modulating CDK5R1 expression. These findings indicate that miR-103 and miR-107 regulate CDK5R1 expression, allowing us to hypothesize that a miRNA-mediated mechanism may influence CDK5 activity and the associated molecular pathways.
Collapse
Affiliation(s)
- Silvia Moncini
- Department of Biology and Genetics for Medical Sciences, University of Milan, Milan, Italy
| | - Alessandro Salvi
- Division of Biology and Genetics, Department of Biomedical Sciences and Biotechnology, University of Brescia, Brescia, Italy
| | - Paola Zuccotti
- Department of Biology and Genetics for Medical Sciences, University of Milan, Milan, Italy
| | - Gabriella Viero
- Centre for Integrative Biology (CIBIO), University of Trento, Trento, Italy
- Institute of Biophysics, National Research Council, Trento, Italy
| | | | - Sergio Barlati
- Division of Biology and Genetics, Department of Biomedical Sciences and Biotechnology, University of Brescia, Brescia, Italy
| | - Giuseppina De Petro
- Division of Biology and Genetics, Department of Biomedical Sciences and Biotechnology, University of Brescia, Brescia, Italy
| | - Marco Venturin
- Department of Biology and Genetics for Medical Sciences, University of Milan, Milan, Italy
| | - Paola Riva
- Department of Biology and Genetics for Medical Sciences, University of Milan, Milan, Italy
- * E-mail:
| |
Collapse
|
10
|
Chow AM, Mok P, Xiao D, Khalouei S, Brown IR. Heteromeric complexes of heat shock protein 70 (HSP70) family members, including Hsp70B', in differentiated human neuronal cells. Cell Stress Chaperones 2010; 15:545-53. [PMID: 20084477 PMCID: PMC3006619 DOI: 10.1007/s12192-009-0167-0] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/28/2009] [Revised: 12/18/2009] [Accepted: 12/22/2009] [Indexed: 12/20/2022] Open
Abstract
Human neurodegenerative disorders such as Alzheimer's disease, Parkinson's disease, and amyotrophic lateral sclerosis have been termed "protein misfolding disorders." Upregulation of heat shock proteins that target misfolded aggregation-prone proteins has been proposed as a potential therapeutic strategy to counter neurodegenerative disorders. The heat shock protein 70 (HSP70) family is well characterized for its cytoprotective effects against cell death and has been implicated in neuroprotection by overexpression studies. HSP70 family members exhibit sequence and structural conservation. The significance of the multiplicity of HSP70 proteins is unknown. In this study, coimmunoprecipitation was employed to determine if association of HSP70 family members occurs, including Hsp70B' which is present in the human genome but not in mouse and rat. Heteromeric complexes of Hsp70B', Hsp70, and Hsc70 were detected in differentiated human SH-SY5Y neuronal cells. Hsp70B' also formed complexes with Hsp40 suggesting a common co-chaperone for HSP70 family members.
Collapse
Affiliation(s)
- Ari M. Chow
- Centre for the Neurobiology of Stress, University of Toronto Scarborough, 1265 Military Trail, Toronto, ON M1C 1A4 Canada
| | - Philip Mok
- Centre for the Neurobiology of Stress, University of Toronto Scarborough, 1265 Military Trail, Toronto, ON M1C 1A4 Canada
| | - Dawn Xiao
- Centre for the Neurobiology of Stress, University of Toronto Scarborough, 1265 Military Trail, Toronto, ON M1C 1A4 Canada
| | - Sam Khalouei
- Centre for the Neurobiology of Stress, University of Toronto Scarborough, 1265 Military Trail, Toronto, ON M1C 1A4 Canada
| | - Ian R. Brown
- Centre for the Neurobiology of Stress, University of Toronto Scarborough, 1265 Military Trail, Toronto, ON M1C 1A4 Canada
| |
Collapse
|
11
|
Vilardo E, Barbato C, Ciotti M, Cogoni C, Ruberti F. MicroRNA-101 regulates amyloid precursor protein expression in hippocampal neurons. J Biol Chem 2010; 285:18344-51. [PMID: 20395292 PMCID: PMC2881760 DOI: 10.1074/jbc.m110.112664] [Citation(s) in RCA: 180] [Impact Index Per Article: 12.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/09/2010] [Revised: 03/24/2010] [Indexed: 12/31/2022] Open
Abstract
The amyloid precursor protein (APP) and its proteolytic product amyloid beta (Abeta) are associated with both familial and sporadic forms of Alzheimer disease (AD). Aberrant expression and function of microRNAs has been observed in AD. Here, we show that in rat hippocampal neurons cultured in vitro, the down-regulation of Argonaute-2, a key component of the RNA-induced silencing complex, produced an increase in APP levels. Using site-directed mutagenesis, a microRNA responsive element (RE) for miR-101 was identified in the 3'-untranslated region (UTR) of APP. The inhibition of endogenous miR-101 increased APP levels, whereas lentiviral-mediated miR-101 overexpression significantly reduced APP and Abeta load in hippocampal neurons. In addition, miR-101 contributed to the regulation of APP in response to the proinflammatory cytokine interleukin-1beta (IL-lbeta). Thus, miR-101 is a negative regulator of APP expression and affects the accumulation of Abeta, suggesting a possible role for miR-101 in neuropathological conditions.
Collapse
Affiliation(s)
- Elisa Vilardo
- From the INMM-Istituto di Neurobiologia e Medicina Molecolare, CNR, and
| | - Christian Barbato
- From the INMM-Istituto di Neurobiologia e Medicina Molecolare, CNR, and
- EBRI-European Brain Research Institute-Fondazione EBRI-Rita Levi-Montalcini, Via del Fosso di Fiorano, 64/65, 00143 Roma, Italy and
| | | | - Carlo Cogoni
- EBRI-European Brain Research Institute-Fondazione EBRI-Rita Levi-Montalcini, Via del Fosso di Fiorano, 64/65, 00143 Roma, Italy and
- the Dipartimento di Biotecnologie Cellulari ed Ematologia, Università di Roma “La Sapienza”, Viale Regina Elena, 324, 00161 Roma, Italy
| | - Francesca Ruberti
- From the INMM-Istituto di Neurobiologia e Medicina Molecolare, CNR, and
| |
Collapse
|
12
|
Patel N, Hoang D, Miller N, Ansaloni S, Huang Q, Rogers JT, Lee JC, Saunders AJ. MicroRNAs can regulate human APP levels. Mol Neurodegener 2008; 3:10. [PMID: 18684319 PMCID: PMC2529281 DOI: 10.1186/1750-1326-3-10] [Citation(s) in RCA: 138] [Impact Index Per Article: 8.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/21/2008] [Accepted: 08/06/2008] [Indexed: 12/20/2022] Open
Abstract
A number of studies have shown that increased APP levels, resulting from either a genomic locus duplication or alteration in APP regulatory sequences, can lead to development of early-onset dementias, including Alzheimer's disease (AD). Therefore, understanding how APP levels are regulated could provide valuable insight into the genetic basis of AD and illuminate novel therapeutic avenues for AD. Here we test the hypothesis that APP protein levels can be regulated by miRNAs, evolutionarily conserved small noncoding RNA molecules that play an important role in regulating gene expression. Utilizing human cell lines, we demonstrate that miRNAs hsa-mir-106a and hsa-mir-520c bind to their predicted target sequences in the APP 3'UTR and negatively regulate reporter gene expression. Over-expression of these miRNAs, but not control miRNAs, results in translational repression of APP mRNA and significantly reduces APP protein levels. These results are the first to demonstrate that levels of human APP can be regulated by miRNAs.
Collapse
Affiliation(s)
- Neha Patel
- Department of Bioscience & Biotechnology, Drexel University, Philadelphia, PA, USA.
| | | | | | | | | | | | | | | |
Collapse
|
13
|
Broytman O, Westmark PR, Gurel Z, Malter JS. Rck/p54 interacts with APP mRNA as part of a multi-protein complex and enhances APP mRNA and protein expression in neuronal cell lines. Neurobiol Aging 2008; 30:1962-74. [PMID: 18378046 DOI: 10.1016/j.neurobiolaging.2008.02.011] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/10/2007] [Revised: 01/28/2008] [Accepted: 02/19/2008] [Indexed: 01/25/2023]
Abstract
Overproduction of amyloid precursor protein (APP) and beta-amyloid likely contribute to neurodegeneration seen in Alzheimer's disease (AD). APP mRNA contains several, 3'-untranslated region (UTR), cis-acting regulatory elements. A 52 base element (52sce), immediately downstream from the stop codon, has been previously shown to complex with uncharacterized cytoplasmic proteins. In this study, we purify and identify six proteins that specifically bind to the 52sce, and show that these proteins interact with each other and with APP mRNA in intact human neuroblastoma cells. We also present evidence that at least one of these proteins, the DEAD-box helicase rck/p54, is involved in post-transcriptional regulation, as its overexpression in cultured cells results in elevated levels of APP mRNA and protein. These findings suggest a novel mechanism for post-transcriptional regulation of APP mRNA.
Collapse
Affiliation(s)
- Oleg Broytman
- Department of Pathology and Laboratory Medicine, Neuroscience Training Program, Waisman Center for Developmental Disabilities and Institute on Aging, University of Wisconsin, Madison, 1500 Highland Avenue, Madison, WI 53705, USA
| | | | | | | |
Collapse
|
14
|
Chow AM, Brown IR. Induction of heat shock proteins in differentiated human and rodent neurons by celastrol. Cell Stress Chaperones 2007; 12:237-44. [PMID: 17915556 PMCID: PMC1971233 DOI: 10.1379/csc-269.1] [Citation(s) in RCA: 62] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/22/2023] Open
Abstract
Neurodegenerative disorders such as Alzheimer's disease, Parkinson's disease, and amyotrophic lateral sclerosis have been termed protein misfolding disorders that are characterized by the neuronal accumulation of protein aggregates. Manipulation of the cellular stress-response involving induction of heat shock proteins (Hsps) in differentiated neurons offers a therapeutic strategy to counter conformational changes in neuronal proteins that trigger pathogenic cascades resulting in neurodegenerative diseases. Hsps are protein repair agents that provide a line of defense against misfolded, aggregation-prone proteins. These proteins are not induced in differentiated neurons by conventional heat shock. We have found that celastrol, a quinine methide triterpene, induced expression of a wider set of Hsps, including Hsp70B', in differentiated human neurons grown in tissue culture compared to cultured rodent neuronal cells. Hence the beneficial effect of celastrol against human neurodegenerative diseases may exceed its potential in rodent models of these diseases.
Collapse
Affiliation(s)
- Ari M Chow
- Centre for the Neurobiology of Stress, University of Toronto at Scarborough, 1265 Military Trail, Toronto, ON M1C 1A4, Canada
| | | |
Collapse
|