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Snyder BL, Blackshear PJ. Clinical implications of tristetraprolin (TTP) modulation in the treatment of inflammatory diseases. Pharmacol Ther 2022; 239:108198. [PMID: 35525391 PMCID: PMC9636069 DOI: 10.1016/j.pharmthera.2022.108198] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/04/2022] [Revised: 04/19/2022] [Accepted: 04/25/2022] [Indexed: 11/24/2022]
Abstract
Abnormal regulation of pro-inflammatory cytokine and chemokine mediators can contribute to the excess inflammation characteristic of many autoimmune diseases, such as rheumatoid arthritis, psoriasis, Crohn's disease, type 1 diabetes, and many others. The tristetraprolin (TTP) family consists of a small group of related RNA-binding proteins that bind to preferred AU-rich binding sites within the 3'-untranslated regions of specific mRNAs to promote mRNA deadenylation and decay. TTP deficient mice develop a severe systemic inflammatory syndrome consisting of arthritis, myeloid hyperplasia, dermatitis, autoimmunity and cachexia, due at least in part to the excess accumulation of proinflammatory chemokine and cytokine mRNAs and their encoded proteins. To investigate the possibility that increased TTP expression or activity might have a beneficial effect on inflammatory diseases, at least two mouse models have been developed that provide proof of principle that increasing TTP activity can promote the decay of pro-inflammatory and other relevant transcripts, and decrease the severity of mouse models of inflammatory disease. Animal studies of this type are summarized here, and we briefly review the prospects for harnessing these insights for the development of TTP-based anti-inflammatory treatments in humans.
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Affiliation(s)
- Brittany L Snyder
- Signal Transduction Laboratory, National Institute of Environmental Health Sciences, National Institutes of Health, Research Triangle Park, NC 27709, United States of America; Department of Biochemistry, Duke University Medical Center, Durham, NC 27710, United States of America
| | - Perry J Blackshear
- Signal Transduction Laboratory, National Institute of Environmental Health Sciences, National Institutes of Health, Research Triangle Park, NC 27709, United States of America; Department of Medicine, Duke University Medical Center, Durham, NC 27710, United States of America; Department of Biochemistry, Duke University Medical Center, Durham, NC 27710, United States of America.
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2
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Hicks SN, Venters RA, Blackshear PJ. Backbone and sidechain 1H, 15N and 13C resonance assignments of the free and RNA-bound tandem zinc finger domain of the tristetraprolin family member from Selaginella moellendorffii. BIOMOLECULAR NMR ASSIGNMENTS 2022; 16:153-158. [PMID: 35279790 PMCID: PMC9196822 DOI: 10.1007/s12104-022-10073-8] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/08/2021] [Accepted: 02/24/2022] [Indexed: 06/14/2023]
Abstract
Members of the tristetraprolin (TTP) family of RNA binding proteins (RBPs) regulate the metabolism of a variety of mRNA targets. In mammals, these proteins modulate many physiological processes, including immune cell activation, hematopoiesis, and embryonic development. Regulation of mRNA stability by these proteins requires that the tandem zinc finger (TZF) domain binds initially and directly to target mRNAs, ultimately leading to their deadenylation and decay. Proteins of this type throughout eukarya possess a highly conserved TZF domain, suggesting that they are all capable of high-affinity RNA binding. However, the mechanism of TTP-mediated mRNA decay is largely undefined. Given the vital role that these TTP family proteins play in maintaining RNA homeostasis throughout eukaryotes, we focused here on the first, key step in this process: recognition and binding of the TZF domain to target RNA. For these studies, we chose a primitive plant, the spikemoss Selaginella moellendorffii, which last shared a common ancestor with humans more than a billion years ago. Here we report the near complete backbone and side chain resonance assignments of the spikemoss TZF domain, including: (1) the assignment of the RNA-TZF domain complex, representing one of only two data sets currently available for the entire TTP family of proteins; and (2) the first NMR resonance assignments of the entire TZF domain, in the RNA-free form. This work will serve as the basis for further NMR structural investigations aimed at gaining insights into the process of RNA recognition and the mechanisms of TTP-mediated mRNA decay.
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Affiliation(s)
- Stephanie N Hicks
- Signal Transduction Laboratory, National Institute of Environmental Health Sciences, Research Triangle Park, NC, 27709, USA.
| | - Ronald A Venters
- Duke University NMR Center, Duke University, Durham, NC, 27710, USA
- Department of Radiology, Duke University, Durham, NC, 27710, USA
| | - Perry J Blackshear
- Signal Transduction Laboratory, National Institute of Environmental Health Sciences, Research Triangle Park, NC, 27709, USA
- Department of Medicine, Duke University Medical Center, Durham, NC, 27710, USA
- Department of Biochemistry, Duke University Medical Center, Durham, NC, 27710, USA
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3
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Bai W, Wells ML, Lai WS, Hicks SN, Burkholder AB, Perera L, Kimmel AR, Blackshear PJ. A post-transcriptional regulon controlled by TtpA, the single tristetraprolin family member expressed in Dictyostelium discoideum. Nucleic Acids Res 2021; 49:11920-11937. [PMID: 34718768 DOI: 10.1093/nar/gkab983] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/06/2021] [Revised: 10/05/2021] [Accepted: 10/12/2021] [Indexed: 12/30/2022] Open
Abstract
Post-transcriptional processes mediated by mRNA binding proteins represent important control points in gene expression. In eukaryotes, mRNAs containing specific AU-rich motifs are regulated by binding of tristetraprolin (TTP) family tandem zinc finger proteins, which promote mRNA deadenylation and decay, partly through interaction of a conserved C-terminal CNOT1 binding (CNB) domain with CCR4-NOT protein complexes. The social ameba Dictyostelium discoideum shared a common ancestor with humans more than a billion years ago, and expresses only one TTP family protein, TtpA, in contrast to three members expressed in humans. Evaluation of ttpA null-mutants identified six transcripts that were consistently upregulated compared to WT during growth and early development. The 3'-untranslated regions (3'-UTRs) of all six 'TtpA-target' mRNAs contained multiple TTP binding motifs (UUAUUUAUU), and one 3'-UTR conferred TtpA post-transcriptional stability regulation to a heterologous mRNA that was abrogated by mutations in the core TTP-binding motifs. All six target transcripts were upregulated to similar extents in a C-terminal truncation mutant, in contrast to less severe effects of analogous mutants in mice. All six target transcripts encoded probable membrane proteins. In Dictyostelium, TtpA may control an 'RNA regulon', where a single RNA binding protein, TtpA, post-transcriptionally co-regulates expression of several functionally related proteins.
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Affiliation(s)
- Wenli Bai
- Laboratory of Cellular and Developmental Biology, National Institute of Diabetes and Digestive and Kidney Diseases, Bethesda, MD 20892, USA
| | - Melissa L Wells
- The Signal Transduction Laboratory, National Institute of Environmental Health Sciences, Research Triangle Park, NC 27709, USA
| | - Wi S Lai
- The Signal Transduction Laboratory, National Institute of Environmental Health Sciences, Research Triangle Park, NC 27709, USA
| | - Stephanie N Hicks
- The Signal Transduction Laboratory, National Institute of Environmental Health Sciences, Research Triangle Park, NC 27709, USA
| | - Adam B Burkholder
- Integrative Bioinformatics Support Group, National Institute of Environmental Health Sciences, Research Triangle Park, NC 27709, USA
| | - Lalith Perera
- Genome Integrity and Structural Biology Laboratory, National Institute of Environmental Health Sciences, Research Triangle Park, NC 27709, USA
| | - Alan R Kimmel
- Laboratory of Cellular and Developmental Biology, National Institute of Diabetes and Digestive and Kidney Diseases, Bethesda, MD 20892, USA
| | - Perry J Blackshear
- The Signal Transduction Laboratory, National Institute of Environmental Health Sciences, Research Triangle Park, NC 27709, USA.,The Departments of Medicine and Biochemistry, Duke University Medical Center, Durham, NC 27710, USA
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4
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Lai WS, Stumpo DJ, Wells ML, Gruzdev A, Hicks SN, Nicholson CO, Yang Z, Faccio R, Webster MW, Passmore LA, Blackshear PJ. Importance of the Conserved Carboxyl-Terminal CNOT1 Binding Domain to Tristetraprolin Activity In Vivo. Mol Cell Biol 2019; 39:e00029-19. [PMID: 31036567 PMCID: PMC6580703 DOI: 10.1128/mcb.00029-19] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/17/2019] [Revised: 02/12/2019] [Accepted: 04/19/2019] [Indexed: 01/19/2023] Open
Abstract
Tristetraprolin (TTP) is an anti-inflammatory protein that modulates the stability of certain cytokine/chemokine mRNAs. After initial high-affinity binding to AU-rich elements in 3' untranslated regions of target mRNAs, mediated through its tandem zinc finger (TZF) domain, TTP promotes the deadenylation and ultimate decay of target transcripts. These transcripts and their encoded proteins accumulate abnormally in TTP knockout (KO) mice, leading to a severe inflammatory syndrome. To assess the importance of the highly conserved C-terminal CNOT1 binding domain (CNBD) of TTP to the TTP deficiency phenotype in mice, we created a mouse model in which TTP lacked its CNBD. CNBD deletion mice exhibited a less severe phenotype than the complete TTP KO mice. In macrophages, the stabilization of target transcripts seen in KO mice was partially normalized in the CNBD deletion mice. In cell-free experiments, recombinant TTP lacking its CNBD could still activate target mRNA deadenylation by purified recombinant Schizosaccharomyces pombe CCR4/NOT complexes, although to a lesser extent than full-length TTP. Thus, TTP lacking its CNBD can still act to promote target mRNA instability in vitro and in vivo These data have implications for TTP family members throughout the eukarya, since species from all four kingdoms contain proteins with linked TZF and CNOT1 binding domains.
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Affiliation(s)
- Wi S Lai
- Signal Transduction Laboratory, National Institute of Environmental Health Sciences, Research Triangle Park, North Carolina, USA
| | - Deborah J Stumpo
- Signal Transduction Laboratory, National Institute of Environmental Health Sciences, Research Triangle Park, North Carolina, USA
| | - Melissa L Wells
- Signal Transduction Laboratory, National Institute of Environmental Health Sciences, Research Triangle Park, North Carolina, USA
| | - Artiom Gruzdev
- Reproductive & Developmental Biology Laboratory, National Institute of Environmental Health Sciences, Research Triangle Park, North Carolina, USA
| | - Stephanie N Hicks
- Signal Transduction Laboratory, National Institute of Environmental Health Sciences, Research Triangle Park, North Carolina, USA
| | - Cindo O Nicholson
- Signal Transduction Laboratory, National Institute of Environmental Health Sciences, Research Triangle Park, North Carolina, USA
| | - Zhengfeng Yang
- Department of Orthopaedic Surgery, Washington University School of Medicine, St. Louis, Missouri, USA
- Shriners Hospitals for Children, St. Louis, Missouri, USA
| | - Roberta Faccio
- Department of Orthopaedic Surgery, Washington University School of Medicine, St. Louis, Missouri, USA
- Shriners Hospitals for Children, St. Louis, Missouri, USA
| | | | - Lori A Passmore
- MRC Laboratory of Molecular Biology, Cambridge, United Kingdom
| | - Perry J Blackshear
- Signal Transduction Laboratory, National Institute of Environmental Health Sciences, Research Triangle Park, North Carolina, USA
- Departments of Medicine and Biochemistry, Duke University Medical Center, Durham, North Carolina, USA
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Lai WS, Wells ML, Perera L, Blackshear PJ. The tandem zinc finger RNA binding domain of members of the tristetraprolin protein family. WILEY INTERDISCIPLINARY REVIEWS-RNA 2019; 10:e1531. [PMID: 30864256 DOI: 10.1002/wrna.1531] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/28/2018] [Revised: 02/12/2019] [Accepted: 02/20/2019] [Indexed: 12/23/2022]
Abstract
Tristetraprolin (TTP), the prototype member of the protein family of the same name, was originally discovered as the product of a rapidly inducible gene in mouse cells. Development of a knockout (KO) mouse established that absence of the protein led to a severe inflammatory syndrome, due in part to elevated levels of tumor necrosis factor (TNF). TTP was found to bind directly and with high affinity to specific AU-rich sequences in the 3'-untranslated region of the TNF mRNA. This initial binding led to promotion of TNF mRNA decay and inhibition of its translation. Many additional TTP target mRNAs have since been identified, some of which are cytokines and chemokines involved in the inflammatory response. There are three other proteins in the mouse with similar activities and domain structures, but whose KO phenotypes are remarkably different. Moreover, proteins with similar domain structures and activities have been found throughout eukaryotes, demonstrating that this protein family arose from an ancient ancestor. The defining characteristic of this protein family is the tandem zinc finger (TZF) domain, a 64 amino acid sequence with many conserved residues that is responsible for the direct RNA binding. We discuss here many aspects of this protein domain that have been elucidated since the original discovery of TTP, including its sequence conservation throughout eukarya; its apparent continued evolution in some lineages; its functional dependence on many key conserved residues; its "interchangeability" among evolutionarily distant species; and the evidence that RNA binding is required for the physiological functions of the proteins. This article is categorized under: RNA Interactions with Proteins and Other Molecules > RNA-Protein Complexes RNA Interactions with Proteins and Other Molecules > Protein-RNA Recognition RNA Interactions with Proteins and Other Molecules > Protein-RNA Interactions: Functional Implications.
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Affiliation(s)
- Wi S Lai
- Signal Transduction Laboratory, National Institute of Environmental Health Sciences, Durham, North Carolina
| | - Melissa L Wells
- Signal Transduction Laboratory, National Institute of Environmental Health Sciences, Durham, North Carolina
| | - Lalith Perera
- Genome Integrity and Structural Biology Laboratory, National Institute of Environmental Health Sciences, Durham, North Carolina
| | - Perry J Blackshear
- Signal Transduction Laboratory, National Institute of Environmental Health Sciences, Durham, North Carolina.,Departments of Medicine and Biochemistry, Duke University Medical Center, Durham, North Carolina
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Webster MW, Stowell JA, Passmore LA. RNA-binding proteins distinguish between similar sequence motifs to promote targeted deadenylation by Ccr4-Not. eLife 2019; 8:40670. [PMID: 30601114 PMCID: PMC6340701 DOI: 10.7554/elife.40670] [Citation(s) in RCA: 47] [Impact Index Per Article: 9.4] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/01/2018] [Accepted: 12/28/2018] [Indexed: 12/17/2022] Open
Abstract
The Ccr4-Not complex removes mRNA poly(A) tails to regulate eukaryotic mRNA stability and translation. RNA-binding proteins contribute to specificity by interacting with both Ccr4-Not and target mRNAs, but this is not fully understood. Here, we reconstitute accelerated and selective deadenylation of RNAs containing AU-rich elements (AREs) and Pumilio-response elements (PREs). We find that the fission yeast homologues of Tristetraprolin/TTP and Pumilio/Puf (Zfs1 and Puf3) interact with Ccr4-Not via multiple regions within low-complexity sequences, suggestive of a multipartite interface that extends beyond previously defined interactions. Using a two-color assay to simultaneously monitor poly(A) tail removal from different RNAs, we demonstrate that Puf3 can distinguish between RNAs of very similar sequence. Analysis of binding kinetics reveals that this is primarily due to differences in dissociation rate constants. Consequently, motif quality is a major determinant of mRNA stability for Puf3 targets in vivo and can be used for the prediction of mRNA targets. When a cell needs to make a particular protein, it first copies the instructions from the matching gene into a molecule known as a messenger RNA (or an mRNA for short). The more mRNA copies it makes, the more protein it can produce. A simple way to control protein production is to raise or lower the number of these mRNA messages, and living cells have lots of ways to make this happen. One method involves codes built into the mRNAs themselves. The mRNAs can carry short sequences of genetic letters that can trigger their own destruction. Known as “destabilising motifs”, these sequences attract the attention of a group of proteins called Ccr4-Not. Together these proteins shorten the end of the mRNAs, preparing the molecules for degradation. But how does Ccr4-Not choose which mRNAs to target? Different mRNAs carry different destabilising motifs. This means that when groups of mRNAs all carry the same motif, the cell can destroy them all together. This allows the cell to switch networks of related genes off together without affecting the mRNAs it still needs. What is puzzling is that the destabilising motifs that control different groups of mRNAs can be very similar, and scientists do not yet know how Ccr4-Not can tell the difference, or what triggers it to start breaking down groups of mRNAs. To find out, Webster et al. recreated the system in the laboratory using purified molecules. The test-tube system confirmed previous suggestions that a protein called Puf3 forms a bridge between Ccr4-Not and mRNAs. It acts as a tether, recognising a destabilising motif and linking it to Ccr4-Not. Labelling different mRNAs with two colours of fluorescent dye showed how Puf3 helps the cell to choose which to destroy. Puf3 allows Ccr4-Not to select specific mRNAs from a mixture of molecules. Puf3 could distinguish between mRNAs that differed in a single letter of genetic code. When it matched with the wrong mRNA, it disconnected much faster than when it matched with the right one, preventing Ccr4-Not from linking up. The ability to destroy specific mRNA messages is critical for cell survival. It happens when cells divide, during immune responses such as inflammation, and in early development. Understanding the targets of tethers like Puf3 could help scientists to predict which genes will switch off and when. This could reveal genes that work together, helping to unravel their roles inside cells.
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Affiliation(s)
| | | | - Lori A Passmore
- MRC Laboratory of Molecular Biology, Cambridge, United Kingdom
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Ramos-Alonso L, Romero AM, Polaina J, Puig S, Martínez-Pastor MT. Dissecting mRNA decay and translation inhibition during iron deficiency. Curr Genet 2018; 65:139-145. [PMID: 30128746 DOI: 10.1007/s00294-018-0880-2] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/07/2018] [Revised: 08/13/2018] [Accepted: 08/14/2018] [Indexed: 10/28/2022]
Abstract
Iron participates as a vital cofactor in multiple metabolic pathways. Despite its abundance, iron bioavailability is highly restricted in aerobic and alkaline environments. Therefore, living organisms have evolved multiple adaptive mechanisms to respond to iron scarcity. These strategies include a global remodeling of iron metabolism directed to optimize iron utilization. In the baker's yeast Saccharomyces cerevisiae, this metabolic reorganization is accomplished to a large extent by an mRNA-binding protein called Cth2. Yeast Cth2 belongs to a conserved family of tandem zinc finger containing proteins that specifically bind to transcripts with AU-rich elements and promote their turnover. A recent study has revealed that Cth2 also inhibits the translation of its target mRNAs (Ramos-Alonso et al., PLoS Genet 14:e1007476, https://doi.org/10.1371/journal.pgen.1007476 , 2018). Interestingly, the mammalian Cth2 ortholog known as tristetraprolin (aka TTP/TIS11/ZFP36), which is also implicated in controlling iron metabolism, promotes the decay and prevents the translation of its regulated transcripts. These observations open the possibility to study the relative contribution of altering mRNA stability and translation to the physiological adaptation to iron deficiency, the function played by the different domains within the mRNA-binding protein, and the potential factors implicated in coordinating both post-transcriptional events.
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Affiliation(s)
- Lucía Ramos-Alonso
- Departamento de Biotecnología, Instituto de Agroquímica y Tecnología de Alimentos (IATA), Consejo Superior de Investigaciones Científicas (CSIC), C/ Agustín Escardino 7, Paterna, 46980, Valencia, Spain
| | - Antonia María Romero
- Departamento de Biotecnología, Instituto de Agroquímica y Tecnología de Alimentos (IATA), Consejo Superior de Investigaciones Científicas (CSIC), C/ Agustín Escardino 7, Paterna, 46980, Valencia, Spain
| | - Julio Polaina
- Departamento de Biotecnología, Instituto de Agroquímica y Tecnología de Alimentos (IATA), Consejo Superior de Investigaciones Científicas (CSIC), C/ Agustín Escardino 7, Paterna, 46980, Valencia, Spain
| | - Sergi Puig
- Departamento de Biotecnología, Instituto de Agroquímica y Tecnología de Alimentos (IATA), Consejo Superior de Investigaciones Científicas (CSIC), C/ Agustín Escardino 7, Paterna, 46980, Valencia, Spain.
| | - María Teresa Martínez-Pastor
- Departamento de Bioquímica y Biología Molecular, Universitat de València, Ave. Doctor Moliner 50, Burjassot, 46100, Valencia, Spain.
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Schmidt JA, Danielson KG, Duffner ER, Radecki SG, Walker GT, Shelton A, Wang T, Knepper JE. Regulation of the oncogenic phenotype by the nuclear body protein ZC3H8. BMC Cancer 2018; 18:759. [PMID: 30041613 PMCID: PMC6057032 DOI: 10.1186/s12885-018-4674-1] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/06/2018] [Accepted: 07/18/2018] [Indexed: 01/22/2023] Open
Abstract
BACKGROUND The Zc3h8 gene encodes a protein with three zinc finger motifs in the C-terminal region. The protein has been identified as a component of the Little Elongation Complex, involved in transcription of small nuclear RNAs. ZC3H8 is overexpressed in a number of human and mouse breast cancer cell lines, and elevated mRNA levels are associated with a poorer prognosis for women with breast cancer. METHODS We used RNA silencing to decrease levels of expression in mouse mammary tumor cells and overexpression of ZC3H8 in cells derived from the normal mouse mammary gland. We measured characteristics of cell behavior in vitro, including proliferation, migration, invasion, growth in soft agar, and spheroid growth. We assessed the ability of these cells to form tumors in syngeneic BALB/c mice. ZC3H8 protein was visualized in cells using confocal microscopy. RESULTS Tumor cells with lower ZC3H8 expression exhibited decreased proliferation rates, slower migration, reduced ability to invade through a basement membrane, and decreased anchorage independent growth in vitro. Cells with lower ZC3H8 levels formed fewer and smaller tumors in animals. Overexpression of ZC3H8 in non-tumorigenic COMMA-D cells led to an opposite effect. ZC3H8 protein localized to both PML bodies and Cajal bodies within the nucleus. ZC3H8 has a casein kinase 2 (CK2) phosphorylation site near the N-terminus, and a CK2 inhibitor caused the numerous PML bodies and ZC3H8 to coalesce to a few larger bodies. Removal of the inhibitor restored PML bodies to their original state. A mutant ZC3H8 lacking the predicted CK2 phosphorylation site showed localization and numbers of ZC3H8/PML bodies similar to wild type. In contrast, a mutant constructed with a glutamic acid in place of the phosphorylatable threonine showed dramatically increased numbers of smaller nuclear foci. CONCLUSIONS These experiments demonstrate that Zc3h8 expression contributes to aggressive tumor cell behavior in vitro and in vivo. Our studies show that ZC3H8 integrity is key to maintenance of PML bodies. The work provides a link between the Little Elongation Complex, PML bodies, and the cancer cell phenotype.
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Affiliation(s)
- John A. Schmidt
- Department of Biology, Mendel Science Center, Villanova University, 800 East Lancaster Avenue, Villanova, PA 19085 USA
| | - Keith G. Danielson
- Department of Biology, Mendel Science Center, Villanova University, 800 East Lancaster Avenue, Villanova, PA 19085 USA
| | - Emily R. Duffner
- Department of Biology, Mendel Science Center, Villanova University, 800 East Lancaster Avenue, Villanova, PA 19085 USA
| | - Sara G. Radecki
- Department of Biology, Mendel Science Center, Villanova University, 800 East Lancaster Avenue, Villanova, PA 19085 USA
| | - Gerard T. Walker
- Department of Biology, Mendel Science Center, Villanova University, 800 East Lancaster Avenue, Villanova, PA 19085 USA
| | - Amber Shelton
- Department of Biology, Mendel Science Center, Villanova University, 800 East Lancaster Avenue, Villanova, PA 19085 USA
| | - Tianjiao Wang
- Department of Biology, Mendel Science Center, Villanova University, 800 East Lancaster Avenue, Villanova, PA 19085 USA
| | - Janice E. Knepper
- Department of Biology, Mendel Science Center, Villanova University, 800 East Lancaster Avenue, Villanova, PA 19085 USA
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A Knock-In Tristetraprolin (TTP) Zinc Finger Point Mutation in Mice: Comparison with Complete TTP Deficiency. Mol Cell Biol 2018; 38:MCB.00488-17. [PMID: 29203639 DOI: 10.1128/mcb.00488-17] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/13/2017] [Accepted: 11/25/2017] [Indexed: 01/09/2023] Open
Abstract
Tristetraprolin (TTP) is a tandem CCCH zinc finger protein that can bind to AU-rich element-containing mRNAs and promote their decay. TTP knockout mice develop a severe inflammatory syndrome, largely due to excess tumor necrosis factor (TNF), whose mRNA is a direct target of TTP binding and destabilization. TTP's RNA binding activity and its ability to promote mRNA decay are lost when one of the zinc-coordinating residues of either zinc finger is mutated. To address several long-standing questions about TTP activity in intact animals, we developed a knock-in mouse with a cysteine-to-arginine mutation within the first zinc finger. Homozygous knock-in mice developed a severe inflammatory syndrome that was essentially identical to that of complete TTP deficiency, suggesting that TTP's critical anti-inflammatory role in mammalian physiology is secondary to its ability to bind RNA. In addition, there was no evidence for a "dominant-negative" effect of the mutant allele in heterozygotes, as suggested by previous experiments. Finally, mRNA decay experiments in mutant macrophages demonstrated that TTP can regulate the stability of its own mRNA, albeit to a minor extent. These studies suggest that RNA binding is an essential first step in the physiological activities of members of this protein family.
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10
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Wells ML, Perera L, Blackshear PJ. An Ancient Family of RNA-Binding Proteins: Still Important! Trends Biochem Sci 2017; 42:285-296. [PMID: 28096055 DOI: 10.1016/j.tibs.2016.12.003] [Citation(s) in RCA: 45] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/26/2016] [Revised: 12/08/2016] [Accepted: 12/09/2016] [Indexed: 12/22/2022]
Abstract
RNA-binding proteins are important modulators of mRNA stability, a crucial process that determines the ultimate cellular levels of mRNAs and their encoded proteins. The tristetraprolin (TTP) family of RNA-binding proteins appeared early in the evolution of eukaryotes, and has persisted in modern eukaryotes. The domain structures and biochemical functions of family members from widely divergent lineages are remarkably similar, but their mRNA 'targets' can be very different, even in closely related species. Recent gene knockout studies in species as distantly related as plants, flies, yeasts, and mice have demonstrated crucial roles for these proteins in a wide variety of physiological processes. Inflammatory and hematopoietic phenotypes in mice have suggested potential therapeutic approaches for analogous human disorders.
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Affiliation(s)
- Melissa L Wells
- Signal Transduction Laboratory, National Institute of Environmental Health Sciences, Research Triangle Park, NC 27709, USA
| | - Lalith Perera
- Genome Integrity and Structural Biology Laboratory, National Institute of Environmental Health Sciences, Research Triangle Park, NC 27709, USA
| | - Perry J Blackshear
- Signal Transduction Laboratory, National Institute of Environmental Health Sciences, Research Triangle Park, NC 27709, USA; Departments of Biochemistry and Medicine, Duke University Medical Center, Durham, NC 27710, USA.
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11
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Tristetraprolin as a Therapeutic Target in Inflammatory Disease. Trends Pharmacol Sci 2016; 37:811-821. [PMID: 27503556 DOI: 10.1016/j.tips.2016.07.002] [Citation(s) in RCA: 64] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/18/2016] [Revised: 07/05/2016] [Accepted: 07/07/2016] [Indexed: 11/22/2022]
Abstract
Members of the tristetraprolin (TTP) family of RNA-binding proteins are found in all major eukaryotic groups. TTP family members, from plants through humans, can bind adenosine-uridine rich elements in target mRNAs with high affinity. In mammalian cells, these proteins then promote deadenylation and decay of target transcripts. Four such proteins are found in mice, of which the best studied is TTP. When the gene encoding TTP is disrupted in mice, the animals develop a severe syndrome of arthritis, autoimmunity, cachexia, dermatitis, and myeloid hyperplasia. Conversely, recent overexpression studies have demonstrated protection against several experimental models of immune inflammatory disease. This endogenous anti-inflammatory protein could serve as the basis for novel approaches to therapy of similar conditions in humans.
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12
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Abstract
Eukaryotic gene expression is extensively controlled at the level of mRNA stability and the mechanisms underlying this regulation are markedly different from their archaeal and bacterial counterparts. We propose that two such mechanisms, nonsense‐mediated decay (NMD) and motif‐specific transcript destabilization by CCCH‐type zinc finger RNA‐binding proteins, originated as a part of cellular defense against RNA pathogens. These branches of the mRNA turnover pathway might have been used by primeval eukaryotes alongside RNA interference to distinguish their own messages from those of RNA viruses and retrotransposable elements. We further hypothesize that the subsequent advent of “professional” innate and adaptive immunity systems allowed NMD and the motif‐triggered mechanisms to be efficiently repurposed for regulation of endogenous cellular transcripts. This scenario explains the rapid emergence of archetypical mRNA destabilization pathways in eukaryotes and argues that other aspects of post‐transcriptional gene regulation in this lineage might have been derived through a similar exaptation route.
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Affiliation(s)
- Fursham M Hamid
- School of Biological Sciences, Nanyang Technological University, Singapore, Singapore
| | - Eugene V Makeyev
- School of Biological Sciences, Nanyang Technological University, Singapore, Singapore.,Centre for Developmental Neurobiology, King's College London, London, UK
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Gingerich TJ, Stumpo DJ, Lai WS, Randall TA, Steppan SJ, Blackshear PJ. Emergence and evolution of Zfp36l3. Mol Phylogenet Evol 2015; 94:518-530. [PMID: 26493225 DOI: 10.1016/j.ympev.2015.10.016] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/26/2015] [Revised: 10/06/2015] [Accepted: 10/13/2015] [Indexed: 11/19/2022]
Abstract
In most mammals, the Zfp36 gene family consists of three conserved members, with a fourth member, Zfp36l3, present only in rodents. The ZFP36 proteins regulate post-transcriptional gene expression at the level of mRNA stability in organisms from humans to yeasts, and appear to be expressed in all major groups of eukaryotes. In Mus musculus, Zfp36l3 expression is limited to the placenta and yolk sac, and is important for overall fecundity. We sequenced the Zfp36l3 gene from more than 20 representative species, from members of the Muridae, Cricetidae and Nesomyidae families. Zfp36l3 was not present in Dipodidae, or any families that branched earlier, indicating that this gene is exclusive to the Muroidea superfamily. We provide evidence that Zfp36l3 arose by retrotransposition of an mRNA encoded by a related gene, Zfp36l2 into an ancestral rodent X chromosome. Zfp36l3 has evolved rapidly since its origin, and numerous modifications have developed, including variations in start codon utilization, de novo intron formation by mechanisms including a nested retrotransposition, and the insertion of distinct repetitive regions. One of these repeat regions, a long alanine rich-sequence, is responsible for the full-time cytoplasmic localization of Mus musculus ZFP36L3. In contrast, this repeat sequence is lacking in Peromyscus maniculatus ZFP36L3, and this protein contains a novel nuclear export sequence that controls shuttling between the nucleus and cytosol. Zfp36l3 is an example of a recently acquired, rapidly evolving gene, and its various orthologues illustrate several different mechanisms by which new genes emerge and evolve.
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Affiliation(s)
- Timothy J Gingerich
- Laboratory of Signal Transduction, National Institute of Environmental Health Sciences, Research Triangle Park, NC 27709, USA
| | - Deborah J Stumpo
- Laboratory of Signal Transduction, National Institute of Environmental Health Sciences, Research Triangle Park, NC 27709, USA
| | - Wi S Lai
- Laboratory of Signal Transduction, National Institute of Environmental Health Sciences, Research Triangle Park, NC 27709, USA
| | - Thomas A Randall
- Integrative Bioinformatics, National Institute of Environmental Health Sciences, Research Triangle Park, NC 27709, USA
| | - Scott J Steppan
- Department of Biological Science, Florida State University, Tallahassee, FL 32306, USA
| | - Perry J Blackshear
- Laboratory of Signal Transduction, National Institute of Environmental Health Sciences, Research Triangle Park, NC 27709, USA; Department of Medicine, Duke University Medical Center, Durham, NC 27710, USA; Department of Biochemistry, Duke University Medical Center, Durham, NC 27710, USA.
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