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Papadimitriou E, Thomaidou D. Post-transcriptional mechanisms controlling neurogenesis and direct neuronal reprogramming. Neural Regen Res 2024; 19:1929-1939. [PMID: 38227517 DOI: 10.4103/1673-5374.390976] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2023] [Accepted: 11/08/2023] [Indexed: 01/17/2024] Open
Abstract
Neurogenesis is a tightly regulated process in time and space both in the developing embryo and in adult neurogenic niches. A drastic change in the transcriptome and proteome of radial glial cells or neural stem cells towards the neuronal state is achieved due to sophisticated mechanisms of epigenetic, transcriptional, and post-transcriptional regulation. Understanding these neurogenic mechanisms is of major importance, not only for shedding light on very complex and crucial developmental processes, but also for the identification of putative reprogramming factors, that harbor hierarchically central regulatory roles in the course of neurogenesis and bare thus the capacity to drive direct reprogramming towards the neuronal fate. The major transcriptional programs that orchestrate the neurogenic process have been the focus of research for many years and key neurogenic transcription factors, as well as repressor complexes, have been identified and employed in direct reprogramming protocols to convert non-neuronal cells, into functional neurons. The post-transcriptional regulation of gene expression during nervous system development has emerged as another important and intricate regulatory layer, strongly contributing to the complexity of the mechanisms controlling neurogenesis and neuronal function. In particular, recent advances are highlighting the importance of specific RNA binding proteins that control major steps of mRNA life cycle during neurogenesis, such as alternative splicing, polyadenylation, stability, and translation. Apart from the RNA binding proteins, microRNAs, a class of small non-coding RNAs that block the translation of their target mRNAs, have also been shown to play crucial roles in all the stages of the neurogenic process, from neural stem/progenitor cell proliferation, neuronal differentiation and migration, to functional maturation. Here, we provide an overview of the most prominent post-transcriptional mechanisms mediated by RNA binding proteins and microRNAs during the neurogenic process, giving particular emphasis on the interplay of specific RNA binding proteins with neurogenic microRNAs. Taking under consideration that the molecular mechanisms of neurogenesis exert high similarity to the ones driving direct neuronal reprogramming, we also discuss the current advances in in vitro and in vivo direct neuronal reprogramming approaches that have employed microRNAs or RNA binding proteins as reprogramming factors, highlighting the so far known mechanisms of their reprogramming action.
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Chung D, Shum A, Caraveo G. GAP-43 and BASP1 in Axon Regeneration: Implications for the Treatment of Neurodegenerative Diseases. Front Cell Dev Biol 2020; 8:567537. [PMID: 33015061 PMCID: PMC7494789 DOI: 10.3389/fcell.2020.567537] [Citation(s) in RCA: 70] [Impact Index Per Article: 17.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/29/2020] [Accepted: 08/14/2020] [Indexed: 01/06/2023] Open
Abstract
Growth-associated protein-43 (GAP-43) and brain acid-soluble protein 1 (BASP1) regulate actin dynamics and presynaptic vesicle cycling at axon terminals, thereby facilitating axonal growth, regeneration, and plasticity. These functions highly depend on changes in GAP-43 and BASP1 expression levels and post-translational modifications such as phosphorylation. Interestingly, examinations of GAP-43 and BASP1 in neurodegenerative diseases reveal alterations in their expression and phosphorylation profiles. This review provides an overview of the structural properties, regulations, and functions of GAP-43 and BASP1, highlighting their involvement in neural injury response and regeneration. By discussing GAP-43 and BASP1 in the context of neurodegenerative diseases, we also explore the therapeutic potential of modulating their activities to compensate for neuron loss in neurodegenerative diseases.
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Affiliation(s)
- Daayun Chung
- Department of Neurology, Feinberg School of Medicine, Northwestern University, Chicago, IL, United States
| | - Andrew Shum
- Department of Neurology, Feinberg School of Medicine, Northwestern University, Chicago, IL, United States
| | - Gabriela Caraveo
- Department of Neurology, Feinberg School of Medicine, Northwestern University, Chicago, IL, United States
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Sanna MD, Ghelardini C, Galeotti N. HuD-mediated distinct BDNF regulatory pathways promote regeneration after nerve injury. Brain Res 2017; 1659:55-63. [DOI: 10.1016/j.brainres.2017.01.019] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/28/2016] [Revised: 01/13/2017] [Accepted: 01/14/2017] [Indexed: 11/30/2022]
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De Moliner K, Wolfson ML, Perrone-Bizzozero N, Adamo AM. GAP-43 slows down cell cycle progression via sequences in its 3'UTR. Arch Biochem Biophys 2015; 571:66-75. [PMID: 25721498 DOI: 10.1016/j.abb.2015.02.024] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2014] [Revised: 01/30/2015] [Accepted: 02/18/2015] [Indexed: 12/26/2022]
Abstract
Growth-associated protein 43 (GAP-43) is a neuronal phosphoprotein associated with initial axonal outgrowth and synaptic remodeling and recent work also suggests its involvement in cell cycle control. The complex expression of GAP-43 features transcriptional and posttranscriptional components. However, in some conditions, GAP-43 gene expression is controlled primarily by the interaction of stabilizing or destabilizing RNA-binding proteins (RBPs) with adenine and uridine (AU)-rich instability elements (AREs) in its 3'UTR. Like GAP-43, many proteins involved in cell proliferation are encoded by ARE-containing mRNAs, some of which codify cell-cycle-regulating proteins including cyclin D1. Considering that GAP-43 and cyclin D1 mRNA stabilization may depend on similar RBPs, this study evaluated the participation of GAP-43 in cell cycle control and its underlying mechanisms, particularly the possible role of its 3'UTR, using GAP-43-transfected NIH-3T3 fibroblasts. Our results show an arrest in cell cycle progression in the G0/G1 phase. This arrest may be mediated by the competition of GAP-43 3'UTR with cyclin D1 3'UTR for the binding of Hu proteins such as HuR, which may lead to a decrease in cyclin D1 expression. These results might lead to therapeutic applications involving the use of sequences in the B region of GAP-43 3'UTR to slow down cell cycle progression.
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Affiliation(s)
- Karina De Moliner
- Department of Biological Chemistry, IQUIFIB (UBA-CONICET), School of Pharmacy and Biochemistry, University of Buenos Aires, Junín 956, C1113AAD Buenos Aires, Argentina
| | - Manuel Luis Wolfson
- Department of Biological Chemistry, IQUIFIB (UBA-CONICET), School of Pharmacy and Biochemistry, University of Buenos Aires, Junín 956, C1113AAD Buenos Aires, Argentina
| | - Nora Perrone-Bizzozero
- Department of Neurosciences and Psychiatry, University of New Mexico School of Medicine, Albuquerque, NM, USA
| | - Ana M Adamo
- Department of Biological Chemistry, IQUIFIB (UBA-CONICET), School of Pharmacy and Biochemistry, University of Buenos Aires, Junín 956, C1113AAD Buenos Aires, Argentina.
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Sanna M, Quattrone A, Mello T, Ghelardini C, Galeotti N. The RNA-binding protein HuD promotes spinal GAP43 overexpression in antiretroviral-induced neuropathy. Exp Neurol 2014; 261:343-53. [DOI: 10.1016/j.expneurol.2014.05.017] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/07/2014] [Revised: 05/10/2014] [Accepted: 05/16/2014] [Indexed: 01/20/2023]
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6
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PKC-mediated HuD–GAP43 pathway activation in a mouse model of antiretroviral painful neuropathy. Pharmacol Res 2014; 81:44-53. [DOI: 10.1016/j.phrs.2014.02.004] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/03/2013] [Revised: 02/11/2014] [Accepted: 02/12/2014] [Indexed: 11/23/2022]
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7
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KSRP modulation of GAP-43 mRNA stability restricts axonal outgrowth in embryonic hippocampal neurons. PLoS One 2013; 8:e79255. [PMID: 24244461 PMCID: PMC3828348 DOI: 10.1371/journal.pone.0079255] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/16/2013] [Accepted: 09/20/2013] [Indexed: 12/02/2022] Open
Abstract
The KH-type splicing regulatory protein (KSRP) promotes the decay of AU-rich element (ARE)-containing mRNAs. Although KSRP is expressed in the nervous system, very little is known about its role in neurons. In this study, we examined whether KSRP regulates the stability of the ARE-containing GAP-43 mRNA. We found that KSRP destabilizes this mRNA by binding to its ARE, a process that requires the presence of its fourth KH domain (KH4). Furthermore, KSRP competed with the stabilizing factor HuD for binding to these sequences. We also examined the functional consequences of KSRP overexpression and knockdown on the differentiation of primary hippocampal neurons in culture. Overexpression of full length KSRP or KSRP without its nuclear localization signal hindered axonal outgrowth in these cultures, while overexpression of a mutant protein without the KH4 domain that has less affinity for binding to GAP-43′s ARE had no effect. In contrast, depletion of KSRP led to a rise in GAP-43 mRNA levels and a dramatic increase in axonal length, both in KSRP shRNA transfected cells and neurons cultured from Ksrp+/− and Ksrp −/−embryos. Finally we found that overexpression of GAP-43 rescued the axonal outgrowth deficits seen with KSRP overexpression, but only when cells were transfected with GAP-43 constructs containing 3′ UTR sequences targeting the transport of this mRNA to axons. Together, our results suggest that KSRP is an important regulator of mRNA stability and axonal length that works in direct opposition to HuD to regulate the levels of GAP-43 and other ARE-containing neuronal mRNAs.
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Bronicki LM, Jasmin BJ. Emerging complexity of the HuD/ELAVl4 gene; implications for neuronal development, function, and dysfunction. RNA (NEW YORK, N.Y.) 2013; 19:1019-1037. [PMID: 23861535 PMCID: PMC3708524 DOI: 10.1261/rna.039164.113] [Citation(s) in RCA: 85] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 06/02/2023]
Abstract
Precise control of messenger RNA (mRNA) processing and abundance are increasingly being recognized as critical for proper spatiotemporal gene expression, particularly in neurons. These regulatory events are governed by a large number of trans-acting factors found in neurons, most notably RNA-binding proteins (RBPs) and micro-RNAs (miRs), which bind to specific cis-acting elements or structures within mRNAs. Through this binding mechanism, trans-acting factors, particularly RBPs, control all aspects of mRNA metabolism, ranging from altering the transcription rate to mediating mRNA degradation. In this context the best-characterized neuronal RBP, the Hu/ELAVl family member HuD, is emerging as a key component in multiple regulatory processes--including pre-mRNA processing, mRNA stability, and translation--governing the fate of a substantial amount of neuronal mRNAs. Through its ability to regulate mRNA metabolism of diverse groups of functionally similar genes, HuD plays important roles in neuronal development and function. Furthermore, compelling evidence indicates supplementary roles for HuD in neuronal plasticity, in particular, recovery from axonal injury, learning and memory, and multiple neurological diseases. The purpose of this review is to provide a detailed overview of the current knowledge surrounding the expression and roles of HuD in the nervous system. Additionally, we outline the present understanding of the molecular mechanisms presiding over the localization, abundance, and function of HuD in neurons.
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Nos2 inactivation promotes the development of medulloblastoma in Ptch1(+/-) mice by deregulation of Gap43-dependent granule cell precursor migration. PLoS Genet 2012; 8:e1002572. [PMID: 22438824 PMCID: PMC3305407 DOI: 10.1371/journal.pgen.1002572] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/14/2011] [Accepted: 01/16/2012] [Indexed: 11/23/2022] Open
Abstract
Medulloblastoma is the most common malignant brain tumor in children. A subset of medulloblastoma originates from granule cell precursors (GCPs) of the developing cerebellum and demonstrates aberrant hedgehog signaling, typically due to inactivating mutations in the receptor PTCH1, a pathomechanism recapitulated in Ptch1+/− mice. As nitric oxide may regulate GCP proliferation and differentiation, we crossed Ptch1+/− mice with mice lacking inducible nitric oxide synthase (Nos2) to investigate a possible influence on tumorigenesis. We observed a two-fold higher medulloblastoma rate in Ptch1+/− Nos2−/− mice compared to Ptch1+/− Nos2+/+ mice. To identify the molecular mechanisms underlying this finding, we performed gene expression profiling of medulloblastomas from both genotypes, as well as normal cerebellar tissue samples of different developmental stages and genotypes. Downregulation of hedgehog target genes was observed in postnatal cerebellum from Ptch1+/+ Nos2−/− mice but not from Ptch1+/− Nos2−/− mice. The most consistent effect of Nos2 deficiency was downregulation of growth-associated protein 43 (Gap43). Functional studies in neuronal progenitor cells demonstrated nitric oxide dependence of Gap43 expression and impaired migration upon Gap43 knock-down. Both effects were confirmed in situ by immunofluorescence analyses on tissue sections of the developing cerebellum. Finally, the number of proliferating GCPs at the cerebellar periphery was decreased in Ptch1+/+ Nos2−/− mice but increased in Ptch1+/− Nos2−/− mice relative to Ptch1+/− Nos2+/+ mice. Taken together, these results indicate that Nos2 deficiency promotes medulloblastoma development in Ptch1+/− mice through retention of proliferating GCPs in the external granular layer due to reduced Gap43 expression. This study illustrates a new role of nitric oxide signaling in cerebellar development and demonstrates that the localization of pre-neoplastic cells during morphogenesis is crucial for their malignant progression. Medulloblastoma is a common pediatric brain tumor, a subtype of which is driven by aberrant hedgehog pathway activation in cerebellar granule cell precursors. Although this tumor etiology has been intensively investigated in the well-established Ptch1+/− mouse model, knowledge is still lacking about the molecular interactions between neoplastic transformation and other developmental processes. Nitric oxide (NO) has been reported to be involved in controlling proliferation and differentiation of these cells. Therefore, inactivation of the NO–producing enzyme Nos2 in combination with the mutated Ptch1 gene should provide insight into how developmental regulation influences pathogenesis. Here, we describe a new role for NO in developing neuronal precursors of the cerebellum facilitating physiologically accurate migration via regulation of Gap43. We further demonstrate that disturbance of these processes leads to retention of granule precursor cells to the cerebellar periphery. Together with the sustained proliferation of these cells in combined Ptch1+/− Nos2−/− mice, this effect results in an increased medulloblastoma incidence relative to Ptch1+/− mice and demonstrates a new disease-promoting mechanism in this tumor entity.
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Tanner DC, Qiu S, Bolognani F, Partridge LD, Weeber EJ, Perrone-Bizzozero NI. Alterations in mossy fiber physiology and GAP-43 expression and function in transgenic mice overexpressing HuD. Hippocampus 2008; 18:814-23. [PMID: 18493953 DOI: 10.1002/hipo.20442] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023]
Abstract
HuD is a neuronal RNA-binding protein associated with the stabilization of mRNAs for GAP-43 and other neuronal proteins that are important for nervous system development and learning and memory mechanisms. To better understand the function of this protein, we generated transgenic mice expressing human HuD (HuD-Tg) in adult forebrain neurons. We have previously shown that expression of HuD in adult dentate granule cells results in an abnormal accumulation of GAP-43 mRNA via posttranscriptional mechanisms. Here we show that this mRNA accumulation leads to the ectopic expression of GAP-43 protein in mossy fibers. Electrophysiological analyses of the mossy fiber to CA3 synapse of HuD-Tg mice revealed increases in paired-pulse facilitation (PPF) at short interpulse intervals and no change in long-term potentiation (LTP). Presynaptic calcium transients at the same synapses exhibited faster time constants of decay, suggesting a decrease in the endogenous Ca(2+) buffer capacity of mossy fiber terminals of HuD-Tg mice. Under resting conditions, GAP-43 binds very tightly to calmodulin sequestering it and then releasing it upon PKC-dependent phosphorylation. Therefore, subsequent studies examined the extent of GAP-43 phosphorylation and its association to calmodulin. We found that despite the increased GAP-43 expression in HuD-Tg mice, the levels of PKC-phosphorylated GAP-43 were decreased in these animals. Furthermore, in agreement with the increased proportion of nonphosphorylated GAP-43, HuD-Tg mice showed increased binding of calmodulin to this protein. These results suggest that a significant amount of calmodulin may be trapped in an inactive state, unable to bind free calcium, and activate downstream signaling pathways. In conclusion, we propose that an unregulated expression of HuD disrupts mossy fiber physiology in adult mice in part by altering the expression and phosphorylation of GAP-43 and the amount of free calmodulin available at the synaptic terminal.
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Affiliation(s)
- Daniel C Tanner
- Department of Neurosciences, University of New Mexico HSC, Albuquerque, New Mexico 87106, USA
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11
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Tsuzaka K, Itami Y, Kumazawa C, Suzuki M, Setoyama Y, Yoshimoto K, Suzuki K, Abe T, Takeuchi T. Conservative sequences in 3'UTR of TCRzeta mRNA regulate TCRzeta in SLE T cells. Biochem Biophys Res Commun 2008; 367:311-7. [PMID: 18177736 DOI: 10.1016/j.bbrc.2007.12.145] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/03/2007] [Accepted: 12/18/2007] [Indexed: 01/21/2023]
Abstract
We have demonstrated that T-cell receptor zeta (zeta) mRNA with a 562-bp deleted alternatively spliced 3'-untranslated region (3'UTR) observed in T cells of patients with systemic lupus erythematosus (SLE) can lead to a reduction in zeta and TCR/CD3 (J. Immunol., 2003 & 2005). To determine the region in zeta mRNA 3'UTR for the regulation of zeta, zeta mRNA with 3'UTR truncations ligated into pDON-AI was used to infect murine T-cell hybridoma MA5.8 cells, which do not contain zeta. As a Western blot analysis demonstrated the importance of the regions from +871 to +950, containing conservative sequence 1 (CS1), and +1070 to +1136, containing CS2, for the production of zeta, we constructed MA5.8 mutants carrying zeta mRNA 3'UTR with deletions of these regions (DeltaCS1 and DeltaCS2 mutants). Western blot and FACS analyses showed significant reduction in the cell surface zeta and TCR/CD3 in both these mutants, and IL-2 production was decreased, compared with MA5.8 cells transfected with wild-type zeta mRNA. Furthermore, real-time PCR demonstrated the instability of zeta mRNA with 3'UTR deletions in these MA5.8 mutants. In conclusion, CS1 and CS2 may be responsible for the regulation of zeta and TCR/CD3 through the stability of zeta mRNA in SLE T cells.
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Affiliation(s)
- Kensei Tsuzaka
- Division of Rheumatology, Department of Internal Medicine, Saitama Medical Center, Saitama Medical University, 1981 Kamoda, Kawagoe, Saitama 350-8550, Japan
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Bolognani F, Perrone-Bizzozero NI. RNA–protein interactions and control of mRNA stability in neurons. J Neurosci Res 2008; 86:481-9. [PMID: 17853436 DOI: 10.1002/jnr.21473] [Citation(s) in RCA: 130] [Impact Index Per Article: 8.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
Abstract
In addition to transcription, posttranscriptional mechanisms play a vital role in the control of gene expression. There are multiple levels of posttranscriptional regulation, including mRNA processing, splicing, editing, transport, stability, and translation. Among these, mRNA stability is estimated to control about 5-10% of all human genes. The rate of mRNA decay is regulated by the interaction of cis-acting elements in the transcripts and sequence-specific RNA-binding proteins. One of the most studied cis-acting elements is the AU-rich element (ARE) present in the 3' untranslated region (3'UTR) of several unstable mRNAs. These sequences are targets of many ARE-binding proteins; some of which induce degradation whereas others promote stabilization of the mRNA. Recently, these mechanisms were uncovered in neurons, where they have been associated with different physiological phenomena, from early development and nerve regeneration to learning and memory processes. In this Mini-Review, we briefly discuss the general mechanisms of control of mRNA turnover and present evidence supporting the importance of these mechanisms in the expression of an increasing number of neuronal genes.
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Affiliation(s)
- Federico Bolognani
- Department of Cell Biology and Physiology, University of New Mexico School of Medicine, Albuquerque, New Mexico, USA
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Bolognani F, Tanner DC, Nixon S, Okano HJ, Okano H, Perrone-Bizzozero NI. Coordinated expression of HuD and GAP-43 in hippocampal dentate granule cells during developmental and adult plasticity. Neurochem Res 2007; 32:2142-51. [PMID: 17577668 DOI: 10.1007/s11064-007-9388-8] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/04/2007] [Accepted: 05/15/2007] [Indexed: 01/04/2023]
Abstract
Previous work from our laboratory demonstrated that the RNA-binding protein HuD binds to and stabilizes the GAP-43 mRNA. In this study, we characterized the expression of HuD and GAP-43 mRNA in the hippocampus during two forms of neuronal plasticity. During post-natal development, maximal expression of both molecules was found at P5 and their levels steadily decreased thereafter. At P5, HuD was also present in the subventricular zone, where it co-localized with doublecortin. In the adult hippocampus, the basal levels of HuD and GAP-43 were lower than during development but were significantly increased in the dentate gyrus after seizures. The function of HuD in GAP-43 gene expression was confirmed using HuD-KO mice, in which the GAP-43 mRNA was significantly less stable than in wild type mice. Altogether, these results demonstrate that HuD plays a role in the post-transcriptional control of GAP-43 mRNA in dentate granule cells during developmental and adult plasticity.
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Affiliation(s)
- Federico Bolognani
- Department of Cell Biology and Physiology, University of New Mexico School of Medicine, Albuquerque, NM 87131, USA.
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Forest D, Nishikawa R, Kobayashi H, Parton A, Bayne CJ, Barnes DW. RNA expression in a cartilaginous fish cell line reveals ancient 3' noncoding regions highly conserved in vertebrates. Proc Natl Acad Sci U S A 2007; 104:1224-9. [PMID: 17227856 PMCID: PMC1770858 DOI: 10.1073/pnas.0610350104] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/12/2006] [Indexed: 11/18/2022] Open
Abstract
We have established a cartilaginous fish cell line [Squalus acanthias embryo cell line (SAE)], a mesenchymal stem cell line derived from the embryo of an elasmobranch, the spiny dogfish shark S. acanthias. Elasmobranchs (sharks and rays) first appeared >400 million years ago, and existing species provide useful models for comparative vertebrate cell biology, physiology, and genomics. Comparative vertebrate genomics among evolutionarily distant organisms can provide sequence conservation information that facilitates identification of critical coding and noncoding regions. Although these genomic analyses are informative, experimental verification of functions of genomic sequences depends heavily on cell culture approaches. Using ESTs defining mRNAs derived from the SAE cell line, we identified lengthy and highly conserved gene-specific nucleotide sequences in the noncoding 3' UTRs of eight genes involved in the regulation of cell growth and proliferation. Conserved noncoding 3' mRNA regions detected by using the shark nucleotide sequences as a starting point were found in a range of other vertebrate orders, including bony fish, birds, amphibians, and mammals. Nucleotide identity of shark and human in these regions was remarkably well conserved. Our results indicate that highly conserved gene sequences dating from the appearance of jawed vertebrates and representing potential cis-regulatory elements can be identified through the use of cartilaginous fish as a baseline. Because the expression of genes in the SAE cell line was prerequisite for their identification, this cartilaginous fish culture system also provides a physiologically valid tool to test functional hypotheses on the role of these ancient conserved sequences in comparative cell biology.
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Affiliation(s)
- David Forest
- Mount Desert Island Biological Laboratory, Salisbury Cove, ME 04672
| | - Ryuhei Nishikawa
- Mount Desert Island Biological Laboratory, Salisbury Cove, ME 04672
| | | | - Angela Parton
- Mount Desert Island Biological Laboratory, Salisbury Cove, ME 04672
| | | | - David W. Barnes
- Mount Desert Island Biological Laboratory, Salisbury Cove, ME 04672
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Tsuzaka K, Nozaki K, Kumazawa C, Shiraishi K, Setoyama Y, Yoshimoto K, Abe T, Takeuchi T. TCRzeta mRNA splice variant forms observed in the peripheral blood T cells from systemic lupus erythematosus patients. ACTA ACUST UNITED AC 2006; 28:185-93. [PMID: 16953440 DOI: 10.1007/s00281-006-0035-2] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/31/2006] [Accepted: 06/01/2006] [Indexed: 12/13/2022]
Abstract
Systemic lupus erythematosus (SLE) is a systemic autoimmune disease of unknown etiology. Tyrosine phosphorylation and protein expression of the T-cell receptor zeta chain (zeta) have been reported to be significantly decreased in SLE T cells. In addition, zeta mRNA with alternatively spliced 3' untranslated region (zetamRNA/as-3'UTR) is detected predominantly in SLE T cells, and aberrant zeta mRNA accompanied by the mutations in the open reading frame including zeta mRNA lacking exon7 (zetamRNA/exon7-) is observed in SLE T cells. These zeta mRNA splice variant forms exhibit a reduction in the expression of TCR/CD3 complex and zeta protein on their cell surface due to the instability of zeta mRNA splice variant forms as well as the reduction in interleukin (IL)-2 production after stimulating with anti-CD3 antibody. Data from cDNA microarray showed that 36 genes encoding cytokines and chemokines, including IL-2, IL-15, IL-18, and TGF-beta2, were down-regulated in the MA5.8 cells transfected with the zeta mRNA splice variant forms. Another 16 genes were up-regulated and included genes associated with membranous proteins and cell damage granules, including the genes encoding poliovirus-receptor-related 2, syndecan-1, and granzyme A.
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Affiliation(s)
- Kensei Tsuzaka
- Division of Rheumatology, Department of Internal Medicine, Saitama Medical Center, Saitama Medical University, 1981 Kamoda, Kawagoe, Saitama, 350-8550, Japan.
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16
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Burry RW, Smith CL. HuD distribution changes in response to heat shock but not neurotrophic stimulation. J Histochem Cytochem 2006; 54:1129-38. [PMID: 16801526 PMCID: PMC3957809 DOI: 10.1369/jhc.6a6979.2006] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022] Open
Abstract
Cellular stress leads to a change in distribution of RNA-binding proteins. HuR, a member of the ELAV/Hu family of RNA-binding proteins, is nuclear in distribution and following heat shock is found in large cytoplasmic stress granules where translation is inhibited. HuD, another ELAV/Hu RNA-binding protein, stabilizes the GAP-43 mRNA in response to nerve growth factor (NGF) stimulation in PC12 cells. We were interested in determining the nuclear distribution of HuD and if neurotrophic stimulation induced changes in the distribution of HuD. In PC12 cells, we found, as expected, that HuR translocates from the nucleus to the cytoplasm in response to heat shock. In response to heat shock, HuD forms large cytoplasmic stress granules, consistent with a role for HuD in the cessation of translation. In unstimulated cells, HuD is distributed in small granules in the cytoplasm and is consistently present at low levels in the nucleus. Stimulation of PC12 cells with NGF induces neuronal differentiation including outgrowth of neurites and increased levels of GAP-43 protein, whereas HuD remains localized in small cytoplasm granules and is still present in the nucleus. These results suggest that, following neurotrophic stimulation, the lack of changes in HuD distribution are due to continued steady state of HuD nuclear shuttling in PC12 cells, or that HuD is not normally shuttled from the nucleus in response to NGF.
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Affiliation(s)
- Richard W Burry
- Department of Neuroscience, 4068 Graves Hall, College of Medicine, The Ohio State University, 333 West Tenth Avenue, Columbus, OH, USA.
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Bolognani F, Tanner DC, Merhege M, Deschênes-Furry J, Jasmin B, Perrone-Bizzozero NI. In vivo post-transcriptional regulation of GAP-43 mRNA by overexpression of the RNA-binding protein HuD. J Neurochem 2006; 96:790-801. [PMID: 16405504 DOI: 10.1111/j.1471-4159.2005.03607.x] [Citation(s) in RCA: 50] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
HuD is a neuronal-specific RNA-binding protein that binds to and stabilizes the mRNAs of growth-associated protein-43 (GAP-43) and other neuronal proteins. HuD expression increases during brain development, nerve regeneration, and learning and memory, suggesting that this protein is important for controlling gene expression during developmental and adult plasticity. To examine the function of HuD in vivo, we generated transgenic mice overexpressing human HuD under the control of the calcium-calmodulin-dependent protein kinase IIalpha promoter. The transgene was expressed at high levels throughout the forebrain, including the hippocampal formation, amygdala and cerebral cortex. Using quantitative in situ hybridization, we found that HuD overexpression led to selective increases in GAP-43 mRNA in hippocampal dentate granule cells and neurons in the lateral amygdala and layer V of the neorcortex. In contrast, GAP-43 pre-mRNA levels were unchanged or decreased in the same neuronal populations. Comparison of the levels of mature GAP-43 mRNA and pre-mRNA in the same neurons of transgenic mice suggested that HuD increased the stability of the transcript. Confirming this, mRNA decay assays revealed that the GAP-43 mRNA was more stable in brain extracts from HuD transgenic mice than non-transgenic littermates. In conclusion, our results demonstrate that HuD overexpression is sufficient to increase GAP-43 mRNA stability in vivo.
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Affiliation(s)
- Federico Bolognani
- Department of Neurosciences, University of New Mexico School of Medicine, Albuquerque, NM 87131, USA
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18
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Pascale A, Amadio M, Scapagnini G, Lanni C, Racchi M, Provenzani A, Govoni S, Alkon DL, Quattrone A. Neuronal ELAV proteins enhance mRNA stability by a PKCalpha-dependent pathway. Proc Natl Acad Sci U S A 2005; 102:12065-70. [PMID: 16099831 PMCID: PMC1189326 DOI: 10.1073/pnas.0504702102] [Citation(s) in RCA: 101] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022] Open
Abstract
More than 1 in 20 human genes bear in the mRNA 3' UTR a specific motif called the adenine- and uridine-rich element (ARE), which posttranscriptionally determines its expression in response to cell environmental signals. ELAV (embryonic lethal abnormal vision) proteins are the only known ARE-binding factors that are able to stabilize the bound mRNAs, thereby positively controlling gene expression. Here, we show that in human neuroblastoma SH-SY5Y cells, neuron-specific ELAV (nELAV) proteins (HuB, HuC, and HuD) are up-regulated and redistributed by 15 min of treatment with the activators of PKC phorbol esters and bryostatin-1. PKC stimulation also induces nELAV proteins to colocalize with the translocated PKCalpha isozyme preferentially on the cytoskeleton, with a concomitant increase of nELAV threonine phosphorylation. The same treatment promotes stabilization of growth-associated protein 43 (GAP-43) mRNA, a well known nELAV target, and induces an early increase in GAP-43 protein concentration, again only in the cytoskeletal cell fraction. Genetic or pharmacological inactivation of PKCalpha abolishes nELAV protein cytoskeletal up-regulation, GAP-43 mRNA stabilization, and GAP-43 protein increase, demonstrating the primary role of this specific PKC isozyme in the cascade of nELAV recruitment. Finally, in vivo PKC activation is associated with an up-regulation of nELAV proteins in the hippocampal rat brain. These findings suggest a model for gene expression regulation by nELAV proteins through a PKCalpha-dependent pathway that is relevant for the cellular programs in which ARE-mediated control plays a pivotal role.
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Affiliation(s)
- Alessia Pascale
- Department of Experimental and Applied Pharmacology, University of Pavia, Via Taramelli 14, 27100 Pavia, Italy.
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19
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Smith CL, Afroz R, Bassell GJ, Furneaux HM, Perrone-Bizzozero NI, Burry RW. GAP-43 mRNA in growth cones is associated with HuD and ribosomes. ACTA ACUST UNITED AC 2005; 61:222-35. [PMID: 15389607 DOI: 10.1002/neu.20038] [Citation(s) in RCA: 72] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
The neuron-specific ELAV/Hu family member, HuD, interacts with and stabilizes GAP-43 mRNA in developing neurons, and leads to increased levels of GAP-43 protein. As GAP-43 protein is enriched in growth cones, it is of interest to determine if HuD and GAP-43 mRNA are associated in developing growth cones. HuD granules in growth cones are found in the central domain that is rich in microtubules and ribosomes, in the peripheral domain with its actin network, and in filopodia. This distribution of HuD granules in growth cones is dependent on actin filaments but not on microtubules. GAP-43 mRNA is localized in granules found in both the central and peripheral domains, but not in filopodia. Ribosomes were extensively colocalized with HuD and GAP-43 mRNA granules in the central domain, consistent with a role in the control of GAP-43 mRNA stability in the growth cone. Together, these results demonstrate that many of the components necessary for GAP-43 mRNA translation/stabilization are present within growth cones.
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Affiliation(s)
- Catherine L Smith
- Department of Neuroscience, College of Medicine and Public Health, The Ohio State University, Columbus, Ohio 43210-1239, USA
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20
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De Moliner KL, Wolfson ML, Perrone Bizzozero N, Adamo AM. Growth-associated protein-43 is degraded via the ubiquitin-proteasome system. J Neurosci Res 2005; 79:652-60. [PMID: 15668958 DOI: 10.1002/jnr.20388] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
Growth-associated protein-43 (GAP-43) is a phosphoprotein whose expression in neurons is related to the initial establishment and remodeling of neural connections. GAP-43 gene expression is known to be regulated at both the transcriptional and the postranscriptional levels. However, very little is known about the cellular mechanism involved in the degradation of this protein. Ubiquitin (Ub) is well known for its role in targeting cytoplasmic proteins for degradation by the 26S proteasome. The ubiquitin-proteasome system (UPS) consists of a conserved cascade of three enzymatic components that attach Ub covalently to various substrates and control the degradation of protein involved in several important cellular processes. In this study, we investigated the degradation of GAP-43 in transfected NIH 3T3 cells and neuronal cultures. We found that the proteasome inhibitors, lactacystin and MG132 increased the cellular GAP-43 level, leading to the accumulation of polyubiquitinated forms of this protein in transfected cells and that the Ub-proteasome pathway is also involved in the turnover of this protein in neurons. We conclude based on our findings that GAP-43 is a substrate of the UPS.
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Affiliation(s)
- K L De Moliner
- Departamento de Química Biológica, IQUIFIB, Universidad de Buenos Aires, CONICET, Buenos Aires, Argentina
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21
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Pascale A, Gusev PA, Amadio M, Dottorini T, Govoni S, Alkon DL, Quattrone A. Increase of the RNA-binding protein HuD and posttranscriptional up-regulation of the GAP-43 gene during spatial memory. Proc Natl Acad Sci U S A 2004; 101:1217-22. [PMID: 14745023 PMCID: PMC337033 DOI: 10.1073/pnas.0307674100] [Citation(s) in RCA: 146] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Neuronal ELAV-like proteins (HuB, HuC, and HuD) are highly conserved RNA-binding proteins able to selectively associate with the 3' UTR of a subset of target mRNAs and increase their cytoplasmic stability and rate of translation. We previously demonstrated the involvement of these proteins in learning, reporting that they undergo a sustained up-regulation in the hippocampus of mice trained in a spatial discrimination task. Here, we extend this finding, showing that a similar up-regulation occurs in the hippocampus of rats trained in another spatial learning paradigm, the Morris water maze. HuD, a strictly neuron-specific ELAV-like protein, is shown to increase after learning, with a preferential binding to the cytoskeletal fraction. HuD up-regulation is associated with an enhancement of GAP-43 mRNA and protein levels, with an apparently increased HuD colocalization with the GAP-43 mRNA and an increased association of neuronal ELAV-like proteins with the GAP-43 mRNA. These learning-dependent biochemical events appear to be spatiotemporally controlled, because they do not occur in another brain region involved in learning, the retrosplenial cortex, and at the level of protein expression they show extinction 1 month after training despite memory retention. By contrast, HuD mRNA levels still remain increased after 1 month in the CA1 region. This persistence may have implications for long-term memory recall.
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Affiliation(s)
- Alessia Pascale
- Department of Experimental and Applied Pharmacology, University of Pavia, Via Taramelli 14, 27100 Pavia, Italy.
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22
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Ekström P, Johansson K. Differentiation of ganglion cells and amacrine cells in the rat retina: correlation with expression of HuC/D and GAP-43 proteins. BRAIN RESEARCH. DEVELOPMENTAL BRAIN RESEARCH 2003; 145:1-8. [PMID: 14519488 DOI: 10.1016/s0165-3806(03)00170-6] [Citation(s) in RCA: 46] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/29/2023]
Abstract
In order to understand the development of retinal cells, we have studied the temporal expression of HuC/D protein in embryonic, postnatal and adult rat retina. During development and in the adult retina, practically all cell somata in the ganglion cell layer and the vast majority of conventional amacrine cells in the inner nuclear layer displayed HuC/D immunoreactivity. Most but not all ganglion cells expressed HuC/D at embryonic day 15, suggesting a delay between final mitosis and the initiation of HuC/D expression. Immunoreactivity for HuC/D was also evident in developing but not mature horizontal cells. Combined immunohistochemical visualization of HuC/D protein and the growth-associated protein (GAP-43) showed a distinct localization of GAP-43 in a specific compartment close to the somato-dendritic region of developing HuC/D-positive cell somata. The localization of GAP-43 immunoreactivity to a specific soma compartment became less evident during maturation. Immunoreactivity for HuC/D and GAP-43 was also discernible in horizontal cells at postnatal day 14. In the adult retina, most GAP-43 immunoreactivity was seen in the inner plexiform layer. Detailed analysis showed that HuC/D and GAP-43 expression is restricted to subsets of retinal neurons during development and in the mature retina. Thus, GAP-43 appears to be correlated with initial steps of differentiation and outgrowth of dendritic processes in HuC/D-positive ganglion and amacrine cells.
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Affiliation(s)
- Peter Ekström
- Department of Zoology, Lund University SE-223 64 Lund, Sweden
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23
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Tsuzaka K, Fukuhara I, Setoyama Y, Yoshimoto K, Suzuki K, Abe T, Takeuchi T. TCR zeta mRNA with an alternatively spliced 3'-untranslated region detected in systemic lupus erythematosus patients leads to the down-regulation of TCR zeta and TCR/CD3 complex. JOURNAL OF IMMUNOLOGY (BALTIMORE, MD. : 1950) 2003; 171:2496-503. [PMID: 12928398 DOI: 10.4049/jimmunol.171.5.2496] [Citation(s) in RCA: 45] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
The reduction or absence of TCR zeta-chain (zeta) expression in systemic lupus erythematosus (SLE) patients is thought to be related to the pathogenesis of SLE. Recently, we reported the predominant expression of zeta mRNA containing an alternatively spliced 3'-untranslated region (3'UTR; zetamRNA/as-3'UTR) and a reduction in the expression of zeta mRNA containing the wild-type 3'UTR (zetamRNA/w-3'UTR) in T cells from SLE patients. Here we show that AS3'UTR mutants (MA5.8 cells deficient in zeta protein that have been transfected with zetamRNA/as-3'UTR) exhibit a reduction in the expression of TCR/CD3 complex and zeta protein on their cell surface as well as a reduction in the production of IL-2 after stimulation with anti-CD3 Ab compared with that in wild-type 3'UTR mutants (MA5.8 cells transfected with zetamRNA/w-3'UTR). Furthermore, the real-time PCR analyses demonstrated that the half-life of zetamRNA/as-3'UTR in AS3'UTR mutants (3 h) was much shorter than that of zetamRNA/w-3'UTR in wild-type 3'UTR mutants (15 h). Thus, the lower stability of zetamRNA/as-3'UTR, which is predominant in SLE T cells, may be responsible for the reduced expression of the TCR/CD3 complex, including zeta protein, in SLE T cells.
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MESH Headings
- 3' Untranslated Regions/antagonists & inhibitors
- 3' Untranslated Regions/biosynthesis
- 3' Untranslated Regions/physiology
- 3T3 Cells
- Alternative Splicing/physiology
- Animals
- Cell Line, Tumor
- Cell Membrane/genetics
- Cell Membrane/immunology
- Cell Membrane/metabolism
- Down-Regulation/genetics
- Down-Regulation/immunology
- Humans
- Interleukin-2/antagonists & inhibitors
- Interleukin-2/biosynthesis
- Lupus Erythematosus, Systemic/genetics
- Lupus Erythematosus, Systemic/immunology
- Lupus Erythematosus, Systemic/metabolism
- Membrane Proteins/antagonists & inhibitors
- Membrane Proteins/biosynthesis
- Membrane Proteins/genetics
- Mice
- RNA Stability/genetics
- RNA Stability/immunology
- RNA, Messenger/antagonists & inhibitors
- RNA, Messenger/biosynthesis
- RNA, Messenger/physiology
- Receptor-CD3 Complex, Antigen, T-Cell/antagonists & inhibitors
- Receptor-CD3 Complex, Antigen, T-Cell/biosynthesis
- Receptors, Antigen, T-Cell/antagonists & inhibitors
- Receptors, Antigen, T-Cell/biosynthesis
- Receptors, Antigen, T-Cell/genetics
- Sequence Deletion
- Transfection
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Affiliation(s)
- Kensei Tsuzaka
- Second Department of Internal Medicine, Saitama Medical Center, Saitama Medical School, Kamoda 1981, Kawagoe, Saitama 350-8550, Japan.
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24
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Anderson KD, Merhege MA, Morin M, Bolognani F, Perrone-Bizzozero NI. Increased expression and localization of the RNA-binding protein HuD and GAP-43 mRNA to cytoplasmic granules in DRG neurons during nerve regeneration. Exp Neurol 2003; 183:100-8. [PMID: 12957493 DOI: 10.1016/s0014-4886(03)00103-1] [Citation(s) in RCA: 50] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
Abstract
The neuronal-specific RNA-binding protein, HuD, binds to a U-rich regulatory element of the 3' untranslated region (3' UTR) of the GAP-43 mRNA and delays the onset of its degradation. We have recently shown that overexpression of HuD in embryonic rat cortical cells accelerated the time course of normal neurite outgrowth and resulted in a twofold increase in GAP-43 mRNA levels. Given this evidence, we sought to investigate the involvement of HuD during nerve regeneration. It is known that HuD protein and GAP-43 mRNA are expressed in the dorsal root ganglia (DRG) of adult rat and that GAP-43 is upregulated in DRG neurons during regeneration. In this study, we examined the expression patterns and levels of HuD and GAP-43 mRNA in DRG neurons following sciatic nerve injury using a combination of in situ hybridization, immunocytochemistry, and quantitative RT-PCR. GAP-43 and HuD expression increased in the ipsilateral DRG during the first 3 weeks of regeneration, with peak values seen at 7 days postcrush. At this time point, the levels of HuD and GAP-43 mRNAs in the ipsilateral DRG increased by twofold and sixfold, respectively, relative to the contralateral DRG. Not only were the temporal patterns of expression of HuD protein and GAP-43 mRNA similar, but also they were found to colocalize in the cytoplasm of DRG neurons. Moreover, both molecules were distributed in cytoplasmic granules containing ribosomal RNA. In conclusion, our results suggest that HuD is involved in the upregulation of GAP-43 expression observed at early stages of peripheral nerve regeneration.
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Affiliation(s)
- K D Anderson
- Department of Neurosciences, University of New Mexico School of Medicine, Albuquerque, NM 87131-5223, USA
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25
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Deschenes-Furry J, Belanger G, Perrone-Bizzozero N, Jasmin BJ. Post-transcriptional regulation of acetylcholinesterase mRNAs in nerve growth factor-treated PC12 cells by the RNA-binding protein HuD. J Biol Chem 2003; 278:5710-7. [PMID: 12468554 DOI: 10.1074/jbc.m209383200] [Citation(s) in RCA: 53] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023] Open
Abstract
Expression of acetylcholinesterase (AChE) is greatly enhanced during neuronal differentiation, but the nature of the molecular mechanisms remains to be fully defined. In this study, we observed that nerve growth factor treatment of PC12 cells leads to a progressive increase in the expression of AChE transcripts, reaching approximately 3.5-fold by 72 h. Given that the AChE 3'-untranslated region (UTR) contains an AU-rich element, we focused on the potential role of the RNA-binding protein HuD in mediating the increase in AChE mRNA seen in differentiating neurons. Using PC12 cells engineered to stably express HuD or an antisense to HuD, our studies indicate that HuD can regulate the abundance of AChE transcripts in neuronal cells. Furthermore, transfection of a reporter construct containing the AChE 3'-UTR showed that this 3'-UTR can increase expression of the reporter gene product in cells expressing HuD but not in cells expressing the antisense. RNA gel shifts and Northwestern blots revealed an increase in the binding of several protein complexes in differentiated neurons. Immunoprecipitation experiments demonstrated that HuD can bind directly AChE transcripts. These results show the importance of post-transcriptional mechanisms in regulating AChE expression in differentiating neurons and implicate HuD as a key trans-acting factor in these events.
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Affiliation(s)
- Julie Deschenes-Furry
- Department of Cellular and Molecular Medicine and Centre for Neuromuscular Disease, Faculty of Medicine, University of Ottawa, Ottawa, Ontario K1H 8M5, Canada
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26
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Uittenbogaard M, Martinka DL, Chiaramello A. The basic helix-loop-helix differentiation factor Nex1/MATH-2 functions as a key activator of the GAP-43 gene. J Neurochem 2003; 84:678-88. [PMID: 12562512 PMCID: PMC1413589 DOI: 10.1046/j.1471-4159.2003.01572.x] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Nex1/MATH-2 is a neurogenic basic Helix-Loop-Helix (bHLH) transcription factor that belongs to the NeuroD subfamily. Its expression parallels that of the GAP-43 gene and peaks during brain development, when neurite outgrowth and synaptogenesis are highly active. We previously observed a direct correlation between the levels of expression of Nex1 and GAP-43 proteins, which resulted in extensive neurite outgrowth and neuronal differentiation of PC12 cells in the absence of nerve growth factor. Since the GAP-43 gene is a target for bHLH regulation, we investigated whether Nex1 could regulate the activity of the GAP-43 promoter. We found that among the members of the NeuroD subfamily, Nex1 promoted maximal activity of the GAP-43 promoter. The Nex1-mediated activity is restricted to the conserved E1-E2 cluster located near the major transcription start sites. By electrophoretic mobility shift assay and site-directed mutagenesis, we showed that Nex1 binds as homodimers and that the E1 E-box is a high affinity binding site. We further found that Nex1 released the ME1 E-protein-mediated repression in a concentration dependent manner. Thus, the E1-E2 cluster has a dual function: it can mediate activation or repression depending on the interacting bHLH proteins. Finally, a series of N-terminal and C-terminal deletions revealed that Nex1 transcriptional activity is linked to two distinct transactivation domains, TAD1 and TAD2, with TAD1 being unique to Nex1. Together, our results suggest that Nex1 may engage in selective interactions with components of the core transcriptional machinery whose assembly is dictated by the architecture of the GAP-43 promoter and cellular environment.
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Affiliation(s)
- Martine Uittenbogaard
- Department of Anatomy and Cell Biology, George Washington University Medical Center, Washington DC, USA
| | - Debra L. Martinka
- Department of Anatomy and Cell Biology, George Washington University Medical Center, Washington DC, USA
- Program of Neuroscience, George Washington University Medical Center, Washington DC, USA
| | - Anne Chiaramello
- Department of Anatomy and Cell Biology, George Washington University Medical Center, Washington DC, USA
- Program of Neuroscience, George Washington University Medical Center, Washington DC, USA
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27
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Irwin N, Chao S, Goritchenko L, Horiuchi A, Greengard P, Nairn AC, Benowitz LI. Nerve growth factor controls GAP-43 mRNA stability via the phosphoprotein ARPP-19. Proc Natl Acad Sci U S A 2002; 99:12427-31. [PMID: 12221279 PMCID: PMC129461 DOI: 10.1073/pnas.152457399] [Citation(s) in RCA: 49] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
The membrane phosphoprotein GAP-43 is involved in axon growth and synaptic plasticity. In PC12 pheochromocytoma cells, induction of a neuronal phenotype by nerve growth factor (NGF) is accompanied by a marked increase in GAP-43 levels. NGF regulates GAP-43 expression by altering the half-life of its mRNA. We report here that the phosphoprotein ARPP-19 mediates this regulation. In an NGF-dependent manner, ARPP-19 bound to a region in the 3' end of GAP-43 mRNA previously found to be important for regulating the half-life of the mRNA. Overexpression of wild-type ARPP-19 in PC12 cells increased the NGF-dependent expression of a reporter construct linked to the critical 3' region of GAP-43 mRNA. Mutation of serine 104, the site of phosphorylation by protein kinase A in ARPP-19, to either alanine or aspartate abolished this regulation in PC12 cells. These findings demonstrate that ARPP-19 is an important link between NGF signaling and post-transcriptional control of neuronal gene expression.
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Affiliation(s)
- Nina Irwin
- Department of Neurosurgery, Children's Hospital, Boston, MA 02115, USA
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28
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Beckel-Mitchener AC, Miera A, Keller R, Perrone-Bizzozero NI. Poly(A) tail length-dependent stabilization of GAP-43 mRNA by the RNA-binding protein HuD. J Biol Chem 2002; 277:27996-8002. [PMID: 12034726 DOI: 10.1074/jbc.m201982200] [Citation(s) in RCA: 79] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
The neuronal ELAV-like RNA-binding protein HuD binds to a regulatory element in the 3'-untranslated region of the growth-associated protein-43 (GAP-43) mRNA. Here we report that overexpression of HuD protein in PC12 cells stabilizes the GAP-43 mRNA by delaying the onset of mRNA degradation and that this process depends on the size of the poly(A) tail. Using a polysome-based in vitro mRNA decay assay, we found that addition of recombinant HuD protein to the system increased the half-life of full-length, capped, and polyadenylated GAP-43 mRNA and that this effect was caused in part by a decrease in the rate of deadenylation of the mRNA. This stabilization was specific for GAP-43 mRNA containing the HuD binding element in the 3'-untranslated region and a poly(A) tail of at least 150 A nucleotides. In correlation with the effect of HuD on GAP-43 mRNA stability, we found that HuD binds GAP-43 mRNAs with long tails (A150) with 10-fold higher affinity than to those with short tails (A30). We conclude that HuD stabilizes the GAP-43 mRNA through a mechanism that is dependent on the length of the poly(A) tail and involves changes in its affinity for the mRNA.
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Affiliation(s)
- Andrea C Beckel-Mitchener
- Department of Neurosciences, University of New Mexico School of Medicine, Albuquerque, New Mexico 87131-5223, USA
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29
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Oishi T, Higo N, Matsuda K, Hayashi M. Expression of super cervical ganglion-10 (SCG-10) mRNA in the monkey cerebral cortex during postnatal development. Neurosci Lett 2002; 323:199-202. [PMID: 11959419 DOI: 10.1016/s0304-3940(02)00142-8] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
Abstract
We used Northern blot analysis to measure SCG10 mRNA expression in various areas of the monkey cerebral cortex during postnatal development. In all areas, SCG10 mRNA expression was highest immediately after birth, decreased sharply until postnatal day 70 (P70) and then decreased slowly until the adult stage. Expression levels were similar in all areas at all time points during development, including the adult stage. These findings confirm that axonal growth in the monkey cerebral cortex is most vigorous before or during the perinatal period, progresses similarly in all areas until P70, and continues at lower levels during late development.
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Affiliation(s)
- Takao Oishi
- Systems Neuroscience Group, Neuroscience Research Institute, National Institute of Advanced Industrial Science and Technology, Umezono, Tsukuba, Ibaraki 305-8568, Japan.
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30
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Perrone-Bizzozero N, Bolognani F. Role of HuD and other RNA-binding proteins in neural development and plasticity. J Neurosci Res 2002; 68:121-6. [PMID: 11948657 DOI: 10.1002/jnr.10175] [Citation(s) in RCA: 144] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
Abstract
Transcription factors have traditionally been viewed as the main determinants of gene expression. Yet, in recent years it has become apparent that RNA-binding proteins also play a critical role in determining the levels of expression of a large number of genes. Once mRNAs are transcribed, RNA-binding proteins can control all subsequent steps in their function, from alternative splicing and translation to mRNA transport and stability. In the nervous system, a large number of genes are regulated post-transcriptionally via the interaction of their mRNAs with specific RNA-binding proteins. This type of regulation is particularly important in the control of the temporal and spatial pattern of gene expression during neural development. This review will discuss the function of the embryonic lethal abnormal vision (ELAV)/Hu family of nervous system-specific RNA-binding proteins, with a special emphasis on HuD, a member of this family that controls GAP-43 mRNA stability and expression. In addition, we will present recent findings on other neural RNA-binding proteins: the ribonucleoprotein K homology (KH)-domain proteins, Fragile X mental retardation protein (FMRP), quakinguiable protein (QKI), and Nova-1. Together with the ELAV/Hu family, these proteins are essential for proper neural development and in some cases for plasticity in the mature brain. The biological significance of these proteins is evident not only by their evolutionary conservation but also by the magnitude of problems arising from autoimmune reactions against them or from mutations affecting their expression or function.
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Affiliation(s)
- Nora Perrone-Bizzozero
- Department of Neurosciences, University of New Mexico School of Medicine, 915 Camino de Salud NE, BMSB Rm. 145, Albuquerque, NM 87131-5223, USA.
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31
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Uittenbogaard M, Chiaramello A. Constitutive overexpression of the basic helix-loop-helix Nex1/MATH-2 transcription factor promotes neuronal differentiation of PC12 cells and neurite regeneration. J Neurosci Res 2002; 67:235-45. [PMID: 11782967 PMCID: PMC2758487 DOI: 10.1002/jnr.10119] [Citation(s) in RCA: 34] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
Elucidation of the intricate transcriptional pathways leading to neural differentiation and the establishment of neuronal identity is critical to the understanding and design of therapeutic approaches. Among the important players, the basic helix-loop-helix (bHLH) transcription factors have been found to be pivotal regulators of neurogenesis. In this study, we investigate the role of the bHLH differentiation factor Nex1/MATH-2 in conjunction with the nerve growth factor (NGF) signaling pathway using the rat phenochromocytoma PC12 cell line. We report that the expression of Nex1 protein is induced after 5 hr of NGF treatment and reaches maximal levels at 24 hr, when very few PC12 cells have begun extending neurites and ceased cell division. Furthermore, our study demonstrates that Nex1 has the ability to trigger neuronal differentiation of PC12 cells in the absence of neurotrophic factor. We show that Nex1 plays an important role in neurite outgrowth and has the capacity to regenerate neurite outgrowth in the absence of NGF. These results are corroborated by the fact that Nex1 targets a repertoire of distinct types of genes associated with neuronal differentiation, such as GAP-43, betaIII-tubulin, and NeuroD. In addition, our findings show that Nex1 up-regulates the expression of the mitotic inhibitor p21(WAF1), thus linking neuronal differentiation to cell cycle withdrawal. Finally, our studies show that overexpression of a Nex1 mutant has the ability to block the execution of NGF-induced differentiation program, suggesting that Nex1 may be an important effector of the NGF signaling pathway.
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Affiliation(s)
- Martine Uittenbogaard
- Department of Anatomy and Cell Biology, George Washington University Medical Center, Washington, DC
| | - Anne Chiaramello
- Department of Anatomy and Cell Biology, George Washington University Medical Center, Washington, DC
- Program of Neuroscience, George Washington University Medical Center, Washington, DC
- Correspondence to: Department of Anatomy and Cell Biology, George Washington University Medical Center, 2300 I Street N.W., Washington, DC 20037.
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Jasmin BJ, Angus LM, Bélanger G, Chakkalakal JV, Gramolini AO, Lunde JA, Stocksley MA, Thompson J. Multiple regulatory events controlling the expression and localization of utrophin in skeletal muscle fibers: insights into a therapeutic strategy for Duchenne muscular dystrophy. JOURNAL OF PHYSIOLOGY, PARIS 2002; 96:31-42. [PMID: 11755781 DOI: 10.1016/s0928-4257(01)00078-x] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
Duchenne muscular dystrophy (DMD) is the most prevalent inherited muscle disease and results from mutations/deletions in the X-linked dystrophin gene. Although several approaches have been envisaged to counteract the effects of this progressive disease, there is currently no cure available. One strategy consists in utilizing a protein normally expressed in DMD muscle which, once expressed at appropriate levels and at the correct subcellular location, could compensate for the lack of dystrophin. A candidate for such a role is the dystrophin-related protein now referred to as utrophin. In contrast to dystrophin, which is expressed along the length of healthy muscle fibers, utrophin accumulates at the neuromuscular junction in both normal and DMD fibers. Several years ago, we began a series of experiments to determine the mechanisms responsible for the expression of utrophin at the neuromuscular synapse. Initially, we showed that utrophin transcripts accumulate preferentially within the postsynaptic sarcoplasm. To determine whether selective transcription of the utrophin gene accounts for this synaptic accumulation of utrophin mRNAs, we injected several utrophin promoter-reporter constructs directly into mouse muscle and demonstrated the preferential synaptic expression of the reporter gene. These results suggested that local transcriptional activation of the utrophin gene is responsible for the accumulation of utrophin mRNAs at the neuromuscular junction. In these studies, we also demonstrated that an N-box motif contained within the utrophin promoter plays a critical role in directing the synapse-specific expression of the utrophin gene. Additionally, our studies have shown that the ets-factors GABP alpha and beta are part of a protein complex that can bind to the N-box motif to transactivate the gene in muscle cells in culture and in vivo. In these experiments, we also noted that the nerve-derived trophic factors agrin and ARIA/heregulin regulate expression of utrophin via the activation of GABP alpha and beta which in turn, transactivate the utrophin gene via the N-box motif. Although these studies demonstrate that transcriptional activation can regulate utrophin mRNA levels, it is possible that additional mechanisms are also involved. In particular, the association of mRNAs with cytoskeletal elements and RNA-binding proteins may contribute to the accumulation of utrophin transcripts within the postsynaptic sarcoplasm. In recent studies, we have begun to examine this and we have now identified specific regions within the 3' untranslated region that are necessary for targeting and stabilizing utrophin mRNAs in skeletal muscle cells. A series of in vivo studies have also led us to conclude that post-transcriptional mechanisms are indeed important in regulating the abundance of utrophin transcripts in muscle. Together, these studies should lead to the identification of cis- and trans-acting elements regulating transcription of the utrophin gene as well as the stability and targeting of its mRNA in muscle cells. The results should therefore, identify specific targets that may become important in designing specific pharmacological interventions directed at increasing the expression of utrophin into extrasynaptic regions of DMD muscle fibers. In addition, these findings will contribute to our basic understanding of the cellular and molecular events involved in the formation, maintenance and plasticity of the neuromuscular synapse.
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Affiliation(s)
- Bernard J Jasmin
- Department of Cellular and Molecular Medicine and Centre for Neuromuscular Disease, Faculty of Medicine, University of Ottawa, and Ottawa Health Research Institute, Ottawa, Ontario, Canada K1H 8M5.
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Carrington M, Nelson G, O'Brien SJ. Considering genetic profiles in functional studies of immune responsiveness to HIV-1. Immunol Lett 2001; 79:131-40. [PMID: 11595300 DOI: 10.1016/s0165-2478(01)00275-9] [Citation(s) in RCA: 44] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
Over the last two decades HIV-1 has spread worldwide and has now surpassed malaria as the leading cause of infectious disease mortality in adults (http://www.who.int/infectious-disease-report/pages/ch1text.html). The clinical course and outcome of HIV-1 infection are highly variable among individuals. Most individuals infected with HIV develop AIDS within 10 years. However about 1-5% remain relatively healthy for 15 years or more (long-term nonprogressors), while others progress to AIDS within the first 2-3 years after infection (rapid progressors). A small number of individuals are resistant to infection, while some individuals appear to eliminate the virus. Factors that influence susceptibility to infection and rate of disease progression are a combination of viral, host, and environmental determinants. With few exceptions, genetic resistance to infectious diseases is likely to involve a complex array of host genetic effects involving variants that have very subtle, but significant consequences on gene expression or protein function. We have gained considerable insight into the genetic effects on HIV-1 disease, yet we likely have uncovered only a fraction of the total picture. The greater our knowledge of various effects on HIV disease, the more likely we will be able to predict disease outcome on an individual-by-individual basis. While this may seem obvious, there is no standard practice of taking into account the genetic profile (i.e. genotypes at loci known to associate with rate of AIDS progression) of subjects used in functional studies of immune responsiveness to HIV-1. Here, we propose an approach for assessing overall genetic risk on an individual basis, and suggest that this information be considered when selecting comparison groups in studies of immune responses to HIV and/or in the interpretation of data derived from such studies.
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Affiliation(s)
- M Carrington
- Intramural Research Support Program, Science Applications International Corporation, and the Laboratory of Genomic Diversity, National Cancer Institute (NCI), P.O. Box B, Frederick, MD 21702-1201, USA.
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Gramolini AO, Bélanger G, Jasmin BJ. Distinct regions in the 3' untranslated region are responsible for targeting and stabilizing utrophin transcripts in skeletal muscle cells. J Cell Biol 2001; 154:1173-83. [PMID: 11551978 PMCID: PMC2150820 DOI: 10.1083/jcb.200101108] [Citation(s) in RCA: 42] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
In this study, we have sought to determine whether utrophin transcripts are targeted to a distinct subcellular compartment in skeletal muscle cells, and have examined the role of the 3' untranslated region (UTR) in regulating the stability and localization of utrophin transcripts. Our results show that utrophin transcripts associate preferentially with cytoskeleton-bound polysomes via actin microfilaments. Because this association is not evident in myoblasts, our findings also indicate that the localization of utrophin transcripts with cytoskeleton-bound polysomes is under developmental influences. Transfection of LacZ reporter constructs containing the utrophin 3'UTR showed that this region is critical for targeting chimeric mRNAs to cytoskeleton-bound polysomes and controlling transcript stability. Deletion studies resulted in the identification of distinct regions within the 3'UTR responsible for targeting and stabilizing utrophin mRNAs. Together, these results illustrate the contribution of posttranscriptional events in the regulation of utrophin in skeletal muscle. Accordingly, these findings provide novel targets, in addition to transcriptional events, for which pharmacological interventions may be envisaged to ultimately increase the endogenous levels of utrophin in skeletal muscle fibers from Duchenne muscular dystrophy (DMD) patients.
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Affiliation(s)
- A O Gramolini
- Department of Cellular and Molecular Medicine, Faculty of Medicine, and Center for Neuromuscular Disease, University of Ottawa, Canada
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35
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Nassar F, Wegnez M. Characterization of two promoters of the Xenopus laevis elrD gene. Biochem Biophys Res Commun 2001; 283:392-8. [PMID: 11327714 DOI: 10.1006/bbrc.2001.4812] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
The Xenopus laevis elrD gene belongs to the multigenic elav/Hu family. elrD is exclusively expressed in neural cells, where it could be involved in the posttranscriptional control of mRNAs. Here we report the isolation and characterization of the genomic elrD 5'-flanking region. We localized the transcription initiation sites and thus identified two distinct transcripts, elrD1 and elrD2 by 5' RACE PCR. The two transcripts derive from the use of alternative promoters located 915 bp apart. We show that sequences upstream of the elrD1 and elrD2 transcription units can direct expression of the reporter luciferase gene in Xenopus embryos. We also observed length variation of the ELRD first RNA recognition motif (RRM1).
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Affiliation(s)
- F Nassar
- Laboratoire d'Embryologie Moléculaire et Expérimentale, UPRES-A 8080, Université Paris-Sud, Bâtiment 445, Orsay, 91405, France
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36
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Anderson KD, Sengupta J, Morin M, Neve RL, Valenzuela CF, Perrone-Bizzozero NI. Overexpression of HuD accelerates neurite outgrowth and increases GAP-43 mRNA expression in cortical neurons and retinoic acid-induced embryonic stem cells in vitro. Exp Neurol 2001; 168:250-8. [PMID: 11259113 DOI: 10.1006/exnr.2000.7599] [Citation(s) in RCA: 79] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
The neuron-specific RNA-binding protein HuD binds to a U-rich regulatory element of the 3' untranslated region (3' UTR) of the GAP-43 mRNA and stabilizes the mRNA. We have previously shown that overexpression of HuD in PC12 cells increases GAP-43 protein expression and induces the spontaneous formation of multiple neurites (K. D. Anderson et al. 2000. J. Neurochem. 75: 1103-1114). In this study, we examined the effects of HuD overexpression on the initial stages of neurite outgrowth and on GAP-43 gene expression using two in vitro systems: E19 rat cortical neurons and retinoic acid (RA)-induced embryonic stem (ES) cells. Normal neurite outgrowth of cortical neurons in vitro occurs over a 3-day period with a concomitant increase in GAP-43 and HuD expression. Cortical cells were infected with a replication-deficient HSV-1 vector containing the HuD cDNA in the sense orientation (HSV-HuD). Overexpression of HuD accelerated the formation of neurites. Immunocytochemical analysis showed that excess HuD resulted in a threefold increase in the number of GAP-43-positive cells undergoing morphological differentiation after 24 h of treatment. Using in situ hybridization, we found that the increased HuD expression resulted in a twofold increase in the levels of GAP-43 mRNA. Similarly, overexpression of HuD in RA-induced embryonic stem cells was found to increase the number of GAP-43-positive cells undergoing process outgrowth. In conclusion, our results demonstrate that HuD functions in the initiation of neurite outgrowth in a manner due, at least in part, to its regulation of GAP-43 expression.
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Affiliation(s)
- K D Anderson
- Department of Neurosciences, University of New Mexico School of Medicine, Albuquerque, New Mexico 87131, USA
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37
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Ikeda K, Kobayashi T, Ichikawa T, Kumanishi T, Niki H, Yano R. The untranslated region of (mu)-opioid receptor mRNA contributes to reduced opioid sensitivity in CXBK mice. J Neurosci 2001; 21:1334-9. [PMID: 11160404 PMCID: PMC6762225] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/18/2023] Open
Abstract
It is well known that there are individual differences in a sensitivity to analgesics. Several lines of evidence have suggested that the level of opioid-induced analgesia is dependent on the level of expression of the mu-opioid receptor (mu-OR). However, the molecular mechanisms underlying the diversity of the level of the opioid receptor and the opioid sensitivity among individuals remain to be elucidated. In the present study, we analyzed the opioid-receptor genes of CXBK recombinant-inbred mice, which show reduced sensitivity to opioids. Northern blotting, nucleotide sequencing, and in situ hybridization histochemical analyses demonstrated that CXBK mice possessed mu-OR mRNA with a normal coding region but an abnormally long untranslated region (UTR). In addition, the mu-OR mRNA level in CXBK mice was less than in the control mice. Next, we produced littermate mice that had inherited two copies of the wild-type mu-OR gene, had inherited two copies of the CXBK mu-OR gene, and had inherited both copies of the mu-OR genes. In these mice, inheritance of the CXBK mu-OR gene was well correlated with less mu-OR mRNA and reduced opioid effects on nociception and locomotor activity. We conclude that the CXBK mu-OR gene is responsible for the CXBK phenotypes. Because UTR differences are known to affect the level of the corresponding mRNA and protein and because UTRs are more divergent among individuals than coding regions, the present findings suggest that opioid sensitivity may vary, depending on different mu-OR levels attributable to divergent UTR of mu-OR mRNA.
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MESH Headings
- Animals
- Brain/metabolism
- DNA Mutational Analysis
- DNA, Complementary/analysis
- DNA, Complementary/genetics
- Drug Resistance/genetics
- Gene Dosage
- Heterozygote
- Homozygote
- In Situ Hybridization
- Male
- Mice
- Mice, Inbred Strains
- Mice, Transgenic
- Molecular Weight
- Morphine/pharmacology
- Motor Activity/drug effects
- Motor Activity/genetics
- Pain Measurement/drug effects
- Point Mutation
- RNA, Messenger/genetics
- RNA, Messenger/metabolism
- RNA, Untranslated/genetics
- Receptors, Opioid, kappa/agonists
- Receptors, Opioid, mu/genetics
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Affiliation(s)
- K Ikeda
- Laboratories for Neurobiology of Emotion and Cellular Information Processing, Brain Science Institute, RIKEN, Wako, Saitama 351-0198, Japan.
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38
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Hicar MD, Liu Y, Allen CE, Wu LC. Structure of the human zinc finger protein HIVEP3: molecular cloning, expression, exon-intron structure, and comparison with paralogous genes HIVEP1 and HIVEP2. Genomics 2001; 71:89-100. [PMID: 11161801 DOI: 10.1006/geno.2000.6425] [Citation(s) in RCA: 32] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Here we report the cloning and characterization of HIVEP3, the newest member in the human immunodeficiency virus type 1 enhancer-binding protein family that encodes large zinc finger proteins and regulates transcription via the kappaB enhancer motif. The largest open reading frame of HIVEP3 contains 2406 aa. and is approximately 80% identical to the mouse counterpart. The HIVEP3 gene is located in the chromosomal region 1p34 and is at least 300 kb with 10 exons. RNA studies show that multiple HIVEP3 transcripts are differentially expressed and regulated. Additionally, transcription termination occurs in the ultimate exon, exon 10, or in exon 6. Therefore, HIVEP3 may produce protein isoforms that contain or exclude the carboxyl DNA binding domain and the leucine zipper by alternative RNA splicing and differential polyadenylation. Sequence homologous to HIVEP3 exon 6 is not found in mouse nor are the paralogous genes HIVEP1 and HIVEP2. Zoo-blot analysis suggests that sequences homologous to the human exon 6 are present only in primates and cow. Therefore, a foreign DNA harboring a termination exon likely was inserted into the HIVEP3 locus relatively recently in evolution, resulting in the acquisition of novel gene regulatory mechanisms as well as the generation of structural and functional diversity.
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MESH Headings
- Amino Acid Sequence
- Animals
- Blotting, Northern
- Blotting, Southern
- Brain/metabolism
- Carrier Proteins/chemistry
- Carrier Proteins/genetics
- Chromosomes, Human, Pair 1
- Cloning, Molecular
- Cosmids
- DNA, Complementary/metabolism
- DNA-Binding Proteins/biosynthesis
- DNA-Binding Proteins/chemistry
- DNA-Binding Proteins/genetics
- Exons
- Expressed Sequence Tags
- Gene Library
- Humans
- Introns
- Mice
- Models, Genetic
- Molecular Sequence Data
- Oligonucleotide Probes/metabolism
- Open Reading Frames
- Phylogeny
- Poly A/metabolism
- Protein Isoforms
- Protein Structure, Tertiary
- Reverse Transcriptase Polymerase Chain Reaction
- Sequence Homology, Amino Acid
- Tissue Distribution
- Transcription Factors
- Transcription, Genetic
- Zinc Fingers
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Affiliation(s)
- M D Hicar
- Department of Molecular Virology, Immunology, and Medical Genetics, College of Medicine and Public Health, The Ohio State University, Columbus, Ohio 43210, USA
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39
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McNamara RK, Jiang Y, Streit WJ, Lenox RH. Facial motor neuron regeneration induces a unique spatial and temporal pattern of myristoylated alanine-rich C kinase substrate expression. Neuroscience 2000; 97:581-9. [PMID: 10828540 DOI: 10.1016/s0306-4522(00)00039-7] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
We have previously shown that the myristoylated alanine-rich C kinase substrate, a primary protein kinase C substrate in brain that binds and cross-links filamentous actin, is enriched in neuronal growth cones and is developmentally regulated in brain. Here we examined myristoylated alanine-rich C kinase substrate expression in the facial motor nucleus during axonal regeneration following facial nerve axotomy or facial nerve resection lesions, which impede regeneration, or following motor neuron degeneration induced by the retrograde neurotoxin ricin. For comparative purposes, the protein kinase C substrates myristoylated alanine-rich C kinase substrate-like protein and growth-associated protein-43 were examined in parallel. Myristoylated alanine-rich C kinase substrate messenger RNA exhibited a robust increase in both neurons and non-neuronal cells in the facial motor nucleus beginning four days after axotomy, peaked at seven days (2.5-fold), and declined back to baseline levels by 40 days. Myristoylated alanine-rich C kinase substrate protein similarly exhibited a twofold elevation in the facial motor nucleus determined four and 14 days post-axotomy. Following nerve resection, myristoylated alanine-rich C kinase substrate messenger RNA levels increased at seven days and returned to baseline levels by 40 days. Unlike myristoylated alanine-rich C kinase substrate messenger RNA, myristoylated alanine-rich C kinase substrate-like messenger RNA levels did not increase in the facial motor nucleus at any time point following nerve axotomy or resection, whereas growth-associated protein-43 messenger RNA exhibited a rapid (one day) and prolonged (40 days) elevation in facial motor nucleus neurons following either nerve axotomy or resection. Ricin-induced degeneration of facial motor neurons elevated myristoylated alanine-rich C kinase substrate and myristoylated alanine-rich C kinase substrate-like messenger RNAs in both microglia (lectin-positive) and astrocytes (glial fibrillary acidic protein-positive).Collectively, these data demonstrate that myristoylated alanine-rich C kinase substrate exhibits a unique expression profile in the facial motor nucleus following facial nerve lesions, and it is proposed that myristoylated alanine-rich C kinase substrate may serve to mediate actin-membrane cytoskeletal plasticity in both neurons and glial cells in response to protein kinaseC-mediated signaling during nerve regeneration and degeneration.
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Affiliation(s)
- R K McNamara
- Department of Psychiatry, University of Pennsylvania School of Medicine, Clinical Research Building, Philadelphia, PA 19104-6140, USA.
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40
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Mobarak CD, Anderson KD, Morin M, Beckel-Mitchener A, Rogers SL, Furneaux H, King P, Perrone-Bizzozero NI. The RNA-binding protein HuD is required for GAP-43 mRNA stability, GAP-43 gene expression, and PKC-dependent neurite outgrowth in PC12 cells. Mol Biol Cell 2000; 11:3191-203. [PMID: 10982410 PMCID: PMC14985 DOI: 10.1091/mbc.11.9.3191] [Citation(s) in RCA: 115] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/12/2023] Open
Abstract
The RNA-binding protein HuD binds to a regulatory element in the 3' untranslated region (3' UTR) of the GAP-43 mRNA. To investigate the functional significance of this interaction, we generated PC12 cell lines in which HuD levels were controlled by transfection with either antisense (pDuH) or sense (pcHuD) constructs. pDuH-transfected cells contained reduced amounts of GAP-43 protein and mRNA, and these levels remained low even after nerve growth factor (NGF) stimulation, a treatment that is normally associated with protein kinase C (PKC)-dependent stabilization of the GAP-43 mRNA and neuronal differentiation. Analysis of GAP-43 mRNA stability demonstrated that the mRNA had a shorter half-life in these cells. In agreement with their deficient GAP-43 expression, pDuH cells failed to grow neurites in the presence of NGF or phorbol esters. These cells, however, exhibited normal neurite outgrowth when exposed to dibutyryl-cAMP, an agent that induces outgrowth independently from GAP-43. We observed opposite effects in pcHuD-transfected cells. The GAP-43 mRNA was stabilized in these cells, leading to an increase in the levels of the GAP-43 mRNA and protein. pcHuD cells were also found to grow short spontaneous neurites, a process that required the presence of GAP-43. In conclusion, our results suggest that HuD plays a critical role in PKC-mediated neurite outgrowth in PC12 cells and that this protein does so primarily by promoting the stabilization of the GAP-43 mRNA.
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Affiliation(s)
- C D Mobarak
- Department of Neurosciences, Albuquerque, New Mexico 87131, USA
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41
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Namgung U, Routtenberg A. Transcriptional and post-transcriptional regulation of a brain growth protein: regional differentiation and regeneration induction of GAP-43. Eur J Neurosci 2000; 12:3124-36. [PMID: 10998096 DOI: 10.1046/j.1460-9568.2000.00196.x] [Citation(s) in RCA: 34] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
During axonal regeneration synthesis of different growth-associated proteins is increased. As yet there is no clear picture of the specific contribution made by the transcriptional and post-transcriptional machinery that provides the gene products necessary for process outgrowth. Here we focus our study on the transcriptional processes in neurons by using intron-directed in situ hybridization to the primary transcript of a brain growth protein GAP-43. In most brain regions, levels of primary transcript expression of GAP-43 were highly correlated with levels of its mRNA. However, there were notable dissociations: in hippocampal granule cells, high levels of primary transcript were evident yet no GAP-43 mRNA was detected. In locus coeruleus the reverse was true; there were high levels of GAP-43 mRNA but no detectable primary transcript. A primary transcript antitermination mechanism is proposed to explain the first dissociation, and a post-transcriptional mRNA stabilization mechanism to explain the second. Transcriptional activation during nerve regeneration was monitored by assessing primary transcript induction of GAP-43 in mouse facial motor neurons. This induction, as well as its mRNA, was restricted to the side of the facial nerve crush. Increases were first observed at 24 h with a rapid increase in both measures up to 3 days. To our knowledge, this is the first in vivo evidence demonstrating transcriptional activation of a brain growth protein in regenerating neurons. The present study points to the GAP-43 transcriptional mechanism as a key determinant of GAP-43 synthesis. Along with the recruitment of post-transcriptional mechanisms, such synthesis occurs in response to both intrinsic developmental programs and extrinsic environmental signals.
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Affiliation(s)
- U Namgung
- Cresap Neuroscience Laboratory, 2021 Sheridan Road, Northwestern University, Evanston, IL60208, USA
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42
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Anderson KD, Morin MA, Beckel-Mitchener A, Mobarak CD, Neve RL, Furneaux HM, Burry R, Perrone-Bizzozero NI. Overexpression of HuD, but not of its truncated form HuD I+II, promotes GAP-43 gene expression and neurite outgrowth in PC12 cells in the absence of nerve growth factor. J Neurochem 2000; 75:1103-14. [PMID: 10936192 DOI: 10.1046/j.1471-4159.2000.0751103.x] [Citation(s) in RCA: 73] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
We have previously shown that the RNA-binding protein HuD binds to a regulatory element in the growth-associated protein (GAP)-43 mRNA and that this interaction involves its first two RNA recognition motifs (RRMs). In this study, we investigated the functional significance of this interaction by overexpression of human HuD protein (pcHuD) or its truncated form lacking the third RRM (pcHuD I+II) in PC12 cells. Morphological analysis revealed that pcHuD cells extended short neurites containing GAP-43-positive growth cones in the absence of nerve growth factor (NGF). These processes also contained tubulin and F-actin filaments but were not stained with antibodies against neurofilament M protein. In correlation with this phenotype, pcHuD cells contained higher levels of GAP-43 without changes in levels of other NGF-induced proteins, such as SNAP-25 and tau. In mRNA decay studies, HuD stabilized the GAP-43 mRNA, whereas HuD I+II did not have any effect either on GAP-43 mRNA stability or on the levels of GAP-43 protein. Likewise, pcHuD I+II cells showed no spontaneous neurite outgrowth and deficient outgrowth in response to NGF. Our results indicate that HuD is sufficient to increase GAP-43 gene expression and neurite outgrowth in the absence of NGF and that the third RRM in the protein is critical for this function.
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Affiliation(s)
- K D Anderson
- Department of Neurosciences, University of New Mexico School of Medicine, Albuquerque 87131, USA
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43
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Cañete-Soler R, Schlaepfer WW. Similar poly(C)-sensitive RNA-binding complexes regulate the stability of the heavy and light neurofilament mRNAs. Brain Res 2000; 867:265-79. [PMID: 10837825 DOI: 10.1016/s0006-8993(00)02389-1] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
The potential role of RNA processing in regulating neurofilament (NF) subunit expression and in mediating the neuropathic effects of NF transgenes was explored by determining whether similar regulatory elements and cognate binding factors are present in NF mRNAs. Gel-shift studies were used to compare RNA-binding complexes that assemble on the 3'UTR of the heavy (NF-H), mid-sized (NF-M) and light (NF-L) NF mRNAs when radioactive RNA probes are incubated with high-speed supernatants (S100) of rat brain homogenates. RNA-binding complexes were characterized by their rate of migration in non-denaturing gels and by their ability to be competed with specific homoribopolymers. Similar RNA-binding complexes formed on probes to the 3'UTRs of NF-L and NF-H mRNAs. The complexes were competed with poly(C) and are referred to as poly(C)-sensitive complexes. Their binding sites were localized to a 36 nt sequence in the mid-distal region of the NF-H 3'UTR and to a 45 nt sequence at the proximal edge of the 3'UTR of the NF-L transcript. Although the binding sites showed limited sequence homology, the complexes were cross-competed with unlabeled probes and radioactivity in either probe was cross-linked to a 43 kDa protein. The 43 kDa protein also bound directly to NF-L and NF-H probes in Northwestern blots. Functional studies showed that deletion of the binding sites markedly increased expression of a luciferase reporter gene containing the 3'UTR of NF-L or NF-H by stabilizing the fusion transcripts. Point mutations in the NF-H binding site which prevented formation of the poly(C)-sensitive complex also stabilized the fusion mRNA. The findings reveal a common destabilizing element in the 3'UTR of NF-L and NF-H mRNAs that may be important in coordinating NF subunit expression and in mediating the neuropathic effects of the NF-L and NF-H transgenes in transgenic mice.
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Affiliation(s)
- R Cañete-Soler
- Division of Neuropathology, University of Pennsylvania, Philadelphia, PA 19104, USA.
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Cantallops I, Routtenberg A. Activity-dependent regulation of axonal growth: Posttranscriptional control of the GAP-43 gene by the NMDA receptor in developing hippocampus. ACTA ACUST UNITED AC 1999. [DOI: 10.1002/(sici)1097-4695(19991105)41:2<208::aid-neu4>3.0.co;2-v] [Citation(s) in RCA: 45] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
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45
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Ai LS, Chau LY. Post-transcriptional regulation of H-ferritin mRNA. Identification of a pyrimidine-rich sequence in the 3'-untranslated region associated with message stability in human monocytic THP-1 cells. J Biol Chem 1999; 274:30209-14. [PMID: 10514512 DOI: 10.1074/jbc.274.42.30209] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
We have previously demonstrated that phorbol myristate acetate (PMA) up-regulates H-ferritin gene expression in myeloid cells by stabilization of its message. In the present report, we showed that insertion of the 3'-untranslated region (3'-UTR) of H-ferritin mRNA at the 3'-end of luciferase coding sequence significantly reduced the stability of luciferase mRNA in human monocytic THP-1 cells. However, the half-life of the chimeric transcript was markedly prolonged after PMA treatment. A cytosolic protein factor from THP-1 cells was found to specifically bind to H-ferritin 3'-UTR. PMA treatment of THP-1 cells resulted in the reduction of the RNA binding activity in a time-dependent manner. Deletion analysis and RNase T1 mapping revealed a pyrimidine-rich sequence within the 3'-UTR which interacts with the protein factor. Competition experiments with homoribopolymers further demonstrated the importance of uridines for the binding activity. Point mutations in uridines of the pyrimidine-rich sequence reduced the protein binding to 3'-UTR, while increasing the stability of the chimeric luciferase transcript. Together, these results demonstrate that the pyrimidine-rich sequence in the 3'-UTR is involved in post-transcriptional regulation of H-ferritin gene expression in myeloid cells.
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Affiliation(s)
- L S Ai
- Division of Cardiovascular Research, Institute of Biomedical Sciences, Academia Sinica, Taipei, Taiwan, R.O.C
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46
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Schorge S, Gupta S, Lin Z, McEnery MW, Lipscombe D. Calcium channel activation stabilizes a neuronal calcium channel mRNA. Nat Neurosci 1999; 2:785-90. [PMID: 10461216 DOI: 10.1038/12153] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
We have identified a calcium-dependent pathway in neurons that regulates expression levels of the alpha1B subunit and N channel current. When neurons are depolarized and voltage-gated calcium channels activated, the half-life of cellular N channel alpha1B mRNA is prolonged. This stabilizing effect of depolarization is mediated through the 3' untranslated region of a long form of the alpha1B mRNA and may represent a form of modulation of N-channel levels that does not require changes in gene transcription. Increases in N channel expression would affect several key neuronal functions controlled by calcium, including transmitter release and neurite outgrowth.
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Affiliation(s)
- S Schorge
- Department of Neuroscience, 192 Thayer Street, Brown University, Box 1953, Providence, Rhode Island 02912, USA
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47
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Akamatsu W, Okano HJ, Osumi N, Inoue T, Nakamura S, Sakakibara S, Miura M, Matsuo N, Darnell RB, Okano H. Mammalian ELAV-like neuronal RNA-binding proteins HuB and HuC promote neuronal development in both the central and the peripheral nervous systems. Proc Natl Acad Sci U S A 1999; 96:9885-90. [PMID: 10449789 PMCID: PMC22305 DOI: 10.1073/pnas.96.17.9885] [Citation(s) in RCA: 204] [Impact Index Per Article: 8.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Hu proteins are mammalian embryonic lethal abnormal visual system (ELAV)-like neuronal RNA-binding proteins that contain three RNA recognition motifs. Although Drosophila ELAV is required for the correct differentiation and survival of neurons, the roles played by the Hu genes in the mammalian nervous system remain largely unknown. To explore the in vivo functions of mouse Hu proteins, we overexpressed them in rat pheochromocytoma PC12 cells, where they induced neuronal phenotype in the absence of nerve growth factor. We have characterized the functions of various forms of mHuB and mHuC bearing point mutations or deletions. Mutants of mHuC that had amino acid exchanges in the RNP1 domain of the first or second RNA recognition motifs (RRMs) lost biologic activity as well as RNA-binding activity. In addition, the mutants containing only the third RRM failed to induce the neuronal phenotype in PC12 cells and inhibited the biologic activity of cotransfected wild-type mHuB and mHuC, thus acting as a dominant-negative form. However, these mutants could not suppress the nerve growth factor-induced differentiation of PC12 cells. Further, we misexpressed wild-type and dominant-negative Hu in E9.5 mouse embryos, by using electroporation into the neural tube at the level of the rhombencephalon. mHuB and mHuC induced the ectopic expression of neuronal markers, whereas the dominant-negative forms of mHuB and mHuC suppressed the differentiation of central nervous system motor neurons. From these results, we suggest that Hu proteins are required for neuronal differentiation in the mammalian nervous system.
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Affiliation(s)
- W Akamatsu
- Department of Neuroanatomy, Biomedical Research Center, Osaka University Graduate School of Medicine, 2-2 Yamadaoka, Suita, Osaka 565-0871, Japan
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48
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Aronov S, Marx R, Ginzburg I. Identification of 3'UTR region implicated in tau mRNA stabilization in neuronal cells. J Mol Neurosci 1999; 12:131-45. [PMID: 10527457 DOI: 10.1007/bf02736927] [Citation(s) in RCA: 47] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022]
Abstract
Tau, a neuronal microtubule-associated protein (MAP) plays an important role in the formation and maintenance of neuronal polarity. Tau mRNA is a stable message and exhibits a relatively long half-life in neuronal cells. The regulation of mRNA stability is a crucial determinant in controlling mRNA steady-state levels in neuronal cells and thereby influences gene expression. The half-lives of specific mRNAs may be dependent on specific sequences located at their 3'untranslated region (UTR), which in turn, may be recognized by tissue-specific proteins. To identify the sequence elements involved in tau mRNA stabilization, selected regions of the 3'UTR were subcloned downstream to c-fos reporter mRNA or to the coding region of the tau mRNA. Using stably transfected neuronal cells, we have demonstrated that a fragment of 240 bp (H fragment) located in the 3'UTR can stabilize c-fos and tau mRNAs. Analysis of stably transfected cells indicated that the transfected tau mRNAs are associated with the microtubules of neuronal cells, suggesting that this association may play a role in tau mRNA stabilization. This step may be a prerequisite in the multistep process leading to the subcellular localization of tau mRNA in neuronal cells.
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Affiliation(s)
- S Aronov
- Department of Neurobiology, Weizmann Institute of Science, Rehovot, Israel
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49
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Neve RL, Ivins KJ, Tsai KC, Rogers SL, Perrone-Bizzozero NI. cis-acting regulatory elements in the GAP-43 mRNA 3'-untranslated region can function in trans to suppress endogenous GAP-43 gene expression. BRAIN RESEARCH. MOLECULAR BRAIN RESEARCH 1999; 65:52-60. [PMID: 10036307 DOI: 10.1016/s0169-328x(98)00337-4] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
The expression of the GAP-43 gene is controlled partly by changes in the stability of its mRNA, a process that is mediated by the interaction of specific sequences in the 3'-untranslated region (3'UTR) with neuronal-specific RNA-binding proteins. Limiting amounts of these trans-acting factors are available in the cell, thus we proposed that overexpression of the GAP-43 3'UTR could affect the levels of the endogenous mRNA via competitive binding to specific RNA-binding proteins. In this study, we show that chronic expression of GAP-43 3'UTR sequences in PC12 cells causes the depletion of the endogenous mRNA and consequent reduction of GAP-43 protein levels. The levels of the mRNAs for c-fos, the amyloid precursor protein (APP) and the microtubule associated protein tau, all three containing similar 3'UTR sequences, were not affected by the treatment. These results thus suggest that the effect of excess GAP-43 3'UTR is specific for its corresponding mRNA. We also used an HSV (herpes simplex virus)-1 vector and a mammalian expression vector with an inducible promoter to acutely express a 10 to 50 fold excess of 3'UTR sequences. Under these conditions, we found that transient expression of the GAP-43 3'UTR was effective in inhibiting both GAP-43 gene expression and neurite outgrowth in nerve growth factor (NGF)-treated PC12 cells and in primary neuronal cultures. These results underscore the role of 3'UTR sequences in the control of GAP-43 gene expression and suggest that overexpression of specific 3'UTR sequences could be used as a potential tool for probing the function of other post-transcriptionally-regulated proteins during neuronal differentiation.
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Affiliation(s)
- R L Neve
- Department of Genetics, Harvard Medical School, McLean Hospital, Belmont, MA 02178, USA.
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50
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Cañete-Soler R, Silberg DG, Gershon MD, Schlaepfer WW. Mutation in neurofilament transgene implicates RNA processing in the pathogenesis of neurodegenerative disease. J Neurosci 1999; 19:1273-83. [PMID: 9952405 PMCID: PMC6786029] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/26/1998] [Revised: 11/23/1998] [Accepted: 11/25/1998] [Indexed: 02/10/2023] Open
Abstract
A mouse neurofilament light subunit (NF-L) transgene with a 36 bp c-myc insert at the end of the coding region was found to have neuropathic effects on enteric and motor neurons of transgenic mice. The severity of phenotype was related directly to the levels of transgenic mRNA expression. High levels of transgene expression were lethal to newborn pups, causing profound alterations in the development of the enteric nervous system and extensive vacuolar changes in motor neurons. Lower levels of transgene expression led to a transient stunting of growth and focal alterations of enteric and motor neurons. Because the positioning of the c-myc insert coincided with the location of the major stability determinant of the NF-L mRNA (Cañete-Soler et al., 1998a,b), additional studies were undertaken. These studies showed that the c-myc insert alters the ribonucleoprotein (RNP) complexes that bind to the stability determinant and disrupts their ability to regulate the stability of the transcripts. The findings indicate that expression of an NF-L transgene with a mutant mRNA stability determinant is highly disruptive to enteric and motor neurons and implicate alterations in RNA processing in the pathogenesis of a neurodegenerative condition.
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Affiliation(s)
- R Cañete-Soler
- Division of Neuropathology, University of Pennsylvania Medical School, Philadelphia, Pennsylvania 19104-6079, USA
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