1
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Levengood JD, Potoyan D, Penumutchu S, Kumar A, Zhou Q, Wang Y, Hansen AL, Kutluay S, Roche J, Tolbert BS. Thermodynamic coupling of the tandem RRM domains of hnRNP A1 underlie its pleiotropic RNA binding functions. SCIENCE ADVANCES 2024; 10:eadk6580. [PMID: 38985864 PMCID: PMC11235170 DOI: 10.1126/sciadv.adk6580] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/03/2023] [Accepted: 06/04/2024] [Indexed: 07/12/2024]
Abstract
The functional properties of RNA binding proteins (RBPs) require allosteric regulation through interdomain communication. Despite the importance of allostery to biological regulation, only a few studies have been conducted to describe the biophysical nature by which interdomain communication manifests in RBPs. Here, we show for hnRNP A1 that interdomain communication is vital for the unique stability of its amino-terminal domain, which consists of two RNA recognition motifs (RRMs). These RRMs exhibit drastically different stability under pressure. RRM2 unfolds as an individual domain but remains stable when appended to RRM1. Variants that disrupt interdomain communication between the tandem RRMs show a significant decrease in stability. Carrying these mutations over to the full-length protein for in vivo experiments revealed that the mutations affected the ability of the disordered carboxyl-terminal domain to engage in protein-protein interactions and influenced the protein's RNA binding capacity. Collectively, this work reveals that thermodynamic coupling between the tandem RRMs of hnRNP A1 accounts for its allosteric regulatory functions.
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Affiliation(s)
- Jeffrey D. Levengood
- Department of Biochemistry and Biophysics, University of Pennsylvania, Philadelphia, PA 19104, USA
| | - Davit Potoyan
- Department of Chemistry, Iowa State University, Ames, IA 50011, USA
| | - Srinivasa Penumutchu
- Department of Biochemistry and Biophysics, University of Pennsylvania, Philadelphia, PA 19104, USA
| | - Abhishek Kumar
- Department of Molecular Microbiology, Washington University School of Medicine, St. Louis, MO 63110, USA
| | - Qianzi Zhou
- Department of Molecular Microbiology, Washington University School of Medicine, St. Louis, MO 63110, USA
| | - Yiqing Wang
- Department of Molecular Microbiology, Washington University School of Medicine, St. Louis, MO 63110, USA
- New York University Grossman School of Medicine, New York, NY 10016, USA
| | - Alexandar L. Hansen
- CCIC and Gateway NMR Facility, The Ohio State University, Columbus, OH 43210, USA
| | - Sebla Kutluay
- Department of Molecular Microbiology, Washington University School of Medicine, St. Louis, MO 63110, USA
| | - Julien Roche
- Roy J. Carver Department of Biochemistry, Biophysics and Molecular Biology, Iowa State University, Ames, IA 50011, USA
| | - Blanton S. Tolbert
- Department of Biochemistry and Biophysics, University of Pennsylvania, Philadelphia, PA 19104, USA
- Howard Hughes Medical Institute, Chevy Chase, MD 20815, USA
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2
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White TLA, Jin Y, Roberts SDA, Gable MJ, Morel PA. Phosphorylation of hnRNP A1-Serine 199 Is Not Required for T Cell Differentiation and Function. Immunohorizons 2024; 8:136-146. [PMID: 38334757 PMCID: PMC10916359 DOI: 10.4049/immunohorizons.2300074] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/11/2023] [Accepted: 01/05/2024] [Indexed: 02/10/2024] Open
Abstract
hnRNP A1 is an important RNA-binding protein that influences many stages of RNA processing, including transcription, alternative splicing, mRNA nuclear export, and RNA stability. However, the role of hnRNP A1 in immune cells, specifically CD4+ T cells, remains unclear. We previously showed that Akt phosphorylation of hnRNP A1 was dependent on TCR signal strength and was associated with Treg differentiation. To explore the impact of hnRNP A1 phosphorylation by Akt on CD4+ T cell differentiation, our laboratory generated a mutant mouse model, hnRNP A1-S199A (A1-MUT) in which the major Akt phosphorylation site on hnRNP A1 was mutated to alanine using CRISPR Cas9 technology. Immune profiling of A1-MUT mice revealed changes in the numbers of Tregs in the mesenteric lymph node. We found no significant differences in naive CD4+ T cell differentiation into Th1, Th2, Th17, or T regulatory cells (Tregs) in vitro. In vivo, Treg differentiation assays using OTII-A1-Mut CD4+ T cells exposed to OVA food revealed migration and homing defects in the A1-MUT but no change in Treg induction. A1-MUT mice were immunized with NP- keyhole limpet hemocyanin, and normal germinal center development, normal numbers of NP-specific B cells, and no change in Tfh numbers were observed. In conclusion, Akt phosphorylation of hnRNP A1 S199 does not play a role in CD4+ T cell fate or function in the models tested. This hnRNP A1-S199A mouse model should be a valuable tool to study the role of Akt phosphorylation of hnRNP A1-S199 in different cell types or other mouse models of human disease.
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Affiliation(s)
- Tristan L. A. White
- Department of Immunology, University of Pittsburgh School of Medicine, Pittsburgh, PA
| | - Ye Jin
- Department of Immunology, University of Pittsburgh School of Medicine, Pittsburgh, PA
| | - Sean D. A. Roberts
- Department of Immunology, University of Pittsburgh School of Medicine, Pittsburgh, PA
| | - Matthew J. Gable
- Department of Immunology, University of Pittsburgh School of Medicine, Pittsburgh, PA
| | - Penelope A. Morel
- Department of Immunology, University of Pittsburgh School of Medicine, Pittsburgh, PA
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3
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Fonódi M, Thalwieser Z, Csortos C, Boratkó A. TIMAP, a Regulatory Subunit of Protein Phosphatase 1, Inhibits In Vitro Neuronal Differentiation. Int J Mol Sci 2023; 24:17360. [PMID: 38139189 PMCID: PMC10744335 DOI: 10.3390/ijms242417360] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/22/2023] [Revised: 12/06/2023] [Accepted: 12/07/2023] [Indexed: 12/24/2023] Open
Abstract
TIMAP (TGF-β-inhibited membrane associated protein) is abundant in endothelial cells, and it has been regarded as a member of the myosin phosphatase targeting protein (MYPT) family. Our workgroup previously identified several interacting protein partners of TIMAP and proved its regulatory subunit role for protein phosphatase 1 catalytic subunit (PP1c). TIMAP is also expressed in neuronal cells, but details of its function have not been studied yet. Therefore, we aimed to explore the role of TIMAP in neuronal cells, especially during differentiation. Expression of TIMAP was proved both at mRNA and protein levels in SH-SY5Y human neuroblastoma cells. Differentiation of SH-SY5Y cells was optimized and proved by the detection of neuronal differentiation markers, such as β3-tubulin, nestin and inhibitor of differentiation 1 (ID1) using qPCR and Western blot. We found downregulation of TIMAP during differentiation. In accordance with this, overexpression of recombinant TIMAP attenuated the differentiation of neuronal cells. Moreover, the subcellular localization of TIMAP has changed during differentiation as it translocated from the plasma membrane into the nucleus. The nuclear interactome of TIMAP revealed more than 50 proteins, offering the possibility to further investigate the role of TIMAP in several key physiological pathways of neuronal cells.
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Affiliation(s)
| | | | | | - Anita Boratkó
- Department of Medical Chemistry, Faculty of Medicine, University of Debrecen, Egyetem Tér 1, H-4032 Debrecen, Hungary; (M.F.); (Z.T.); (C.C.)
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4
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Levengood JD, Potoyan D, Penumutchu S, Kumar A, Wang Y, Hansen AL, Kutluay S, Roche J, Tolbert BS. Thermodynamic Coupling of the tandem RRM domains of hnRNP A1 underlie its Pleiotropic RNA Binding Functions. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.08.17.553700. [PMID: 37645738 PMCID: PMC10462124 DOI: 10.1101/2023.08.17.553700] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 08/31/2023]
Abstract
The functional properties of RNA-binding proteins (RBPs) require allosteric regulation through inter-domain communication. Despite the foundational importance of allostery to biological regulation, almost no studies have been conducted to describe the biophysical nature by which inter-domain communication manifests in RBPs. Here, we show through high-pressure studies with hnRNP A1 that inter-domain communication is vital for the unique stability of its N- terminal domain containing a tandem of RNA Recognition Motifs (RRMs). Despite high sequence similarity and nearly identical tertiary structures, the two RRMs exhibit drastically different stability under pressure. RRM2 unfolds completely under high-pressure as an individual domain, but when appended to RRM1, it remains stable. Variants in which inter-domain communication is disrupted between the tandem RRMs show a large decrease in stability under pressure. Carrying these mutations over to the full-length protein for in vivo experiments revealed that the mutations affected the ability of the disordered C-terminus to engage in protein-protein interactions and more importantly, they also influenced the RNA binding capacity. Collectively, this work reveals that thermodynamic coupling between the tandem RRMs of hnRNP A1 accounts for its allosteric regulatory functions.
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5
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Benavides-Serrato A, Saunders JT, Kumar S, Holmes B, Benavides KE, Bashir MT, Nishimura RN, Gera J. m 6A-modification of cyclin D1 and c-myc IRESs in glioblastoma controls ITAF activity and resistance to mTOR inhibition. Cancer Lett 2023; 562:216178. [PMID: 37061119 PMCID: PMC10805108 DOI: 10.1016/j.canlet.2023.216178] [Citation(s) in RCA: 5] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/21/2022] [Revised: 03/17/2023] [Accepted: 04/07/2023] [Indexed: 04/17/2023]
Abstract
A major mechanism conferring resistance to mTOR inhibitors is activation of a salvage pathway stimulating internal ribosome entry site (IRES)-mediated mRNA translation, driving the synthesis of proteins promoting resistance of glioblastoma (GBM). Previously, we found this pathway is stimulated by the requisite IRES-trans-acting factor (ITAF) hnRNP A1, which itself is subject to phosphorylation and methylation events regulating cyclin D1 and c-myc IRES activity. Here we describe the requirement for m6A-modification of IRES RNAs for efficient translation and resistance to mTOR inhibition. DRACH-motifs within these IRES RNAs upon m6A modification resulted in enhanced IRES activity via increased hnRNP A1-binding following mTOR inhibitor exposure. Inhibitor exposure stimulated the expression of m6A-methylosome components resulting in increased activity in GBM. Silencing of METTL3-14 complexes reduced IRES activity upon inhibitor exposure and sensitized resistant GBM lines. YTHDF3 associates with m6A-modified cyclin D1 or c-myc IRESs, regulating IRES activity, and mTOR inhibitor sensitivity in vitro and in xenograft experiments. YTHDF3 interacted directly with hnRNP A1 and together stimulated hnRNP A1-dependent nucleic acid strand annealing activity. These data demonstrate that m6A-methylation of IRES RNAs regulate GBM responses to this class of inhibitors.
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Affiliation(s)
- Angelica Benavides-Serrato
- Department of Medicine, University of California, Los Angeles, CA, USA; Department of Research & Development, Greater Los Angeles Veterans Affairs Healthcare System, Los Angeles, CA, USA
| | - Jacquelyn T Saunders
- Department of Research & Development, Greater Los Angeles Veterans Affairs Healthcare System, Los Angeles, CA, USA
| | - Sunil Kumar
- Department of Research & Development, Greater Los Angeles Veterans Affairs Healthcare System, Los Angeles, CA, USA
| | - Brent Holmes
- Department of Research & Development, Greater Los Angeles Veterans Affairs Healthcare System, Los Angeles, CA, USA
| | - Kennedy E Benavides
- Department of Research & Development, Greater Los Angeles Veterans Affairs Healthcare System, Los Angeles, CA, USA
| | - Muhammad T Bashir
- Department of Medicine, University of California, Los Angeles, CA, USA; Department of Research & Development, Greater Los Angeles Veterans Affairs Healthcare System, Los Angeles, CA, USA
| | - Robert N Nishimura
- Neurology, David Geffen School of Medicine at UCLA, University of California, Los Angeles, CA, USA; Department of Research & Development, Greater Los Angeles Veterans Affairs Healthcare System, Los Angeles, CA, USA
| | - Joseph Gera
- Department of Medicine, University of California, Los Angeles, CA, USA; Jonnson Comprehensive Cancer Center, University of California, Los Angeles, CA, USA; Molecular Biology Institute, University of California, Los Angeles, CA, USA; Department of Research & Development, Greater Los Angeles Veterans Affairs Healthcare System, Los Angeles, CA, USA.
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6
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Montiel-Dávalos A, Ayala Y, Hernández G. The dark side of mRNA translation and the translation machinery in glioblastoma. Front Cell Dev Biol 2023; 11:1086964. [PMID: 36994107 PMCID: PMC10042294 DOI: 10.3389/fcell.2023.1086964] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/01/2022] [Accepted: 03/03/2023] [Indexed: 03/14/2023] Open
Abstract
Among the different types of cancer affecting the central nervous system (CNS), glioblastoma (GB) is classified by the World Health Organization (WHO) as the most common and aggressive CNS cancer in adults. GB incidence is more frequent among persons aged 45–55 years old. GB treatments are based on tumor resection, radiation, and chemotherapies. The current development of novel molecular biomarkers (MB) has led to a more accurate prediction of GB progression. Moreover, clinical, epidemiological, and experimental studies have established genetic variants consistently associated with the risk of suffering GB. However, despite the advances in these fields, the survival expectancy of GB patients is still shorter than 2 years. Thus, fundamental processes inducing tumor onset and progression remain to be elucidated. In recent years, mRNA translation has been in the spotlight, as its dysregulation is emerging as a key cause of GB. In particular, the initiation phase of translation is most involved in this process. Among the crucial events, the machinery performing this phase undergoes a reconfiguration under the hypoxic conditions in the tumor microenvironment. In addition, ribosomal proteins (RPs) have been reported to play translation-independent roles in GB development. This review focuses on the research elucidating the tight relationship between translation initiation, the translation machinery, and GB. We also summarize the state-of-the-art drugs targeting the translation machinery to improve patients’ survival. Overall, the recent advances in this field are shedding new light on the dark side of translation in GB.
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7
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RNA-Binding Proteins as Regulators of Internal Initiation of Viral mRNA Translation. Viruses 2022; 14:v14020188. [PMID: 35215780 PMCID: PMC8879377 DOI: 10.3390/v14020188] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/01/2021] [Revised: 01/03/2022] [Accepted: 01/14/2022] [Indexed: 12/17/2022] Open
Abstract
Viruses are obligate intracellular parasites that depend on the host’s protein synthesis machinery for translating their mRNAs. The viral mRNA (vRNA) competes with the host mRNA to recruit the translational machinery, including ribosomes, tRNAs, and the limited eukaryotic translation initiation factor (eIFs) pool. Many viruses utilize non-canonical strategies such as targeting host eIFs and RNA elements known as internal ribosome entry sites (IRESs) to reprogram cellular gene expression, ensuring preferential translation of vRNAs. In this review, we discuss vRNA IRES-mediated translation initiation, highlighting the role of RNA-binding proteins (RBPs), other than the canonical translation initiation factors, in regulating their activity.
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8
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Thibault PA, Ganesan A, Kalyaanamoorthy S, Clarke JPWE, Salapa HE, Levin MC. hnRNP A/B Proteins: An Encyclopedic Assessment of Their Roles in Homeostasis and Disease. BIOLOGY 2021; 10:biology10080712. [PMID: 34439945 PMCID: PMC8389229 DOI: 10.3390/biology10080712] [Citation(s) in RCA: 16] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 06/15/2021] [Revised: 07/16/2021] [Accepted: 07/21/2021] [Indexed: 12/13/2022]
Abstract
The hnRNP A/B family of proteins is canonically central to cellular RNA metabolism, but due to their highly conserved nature, the functional differences between hnRNP A1, A2/B1, A0, and A3 are often overlooked. In this review, we explore and identify the shared and disparate homeostatic and disease-related functions of the hnRNP A/B family proteins, highlighting areas where the proteins have not been clearly differentiated. Herein, we provide a comprehensive assembly of the literature on these proteins. We find that there are critical gaps in our grasp of A/B proteins' alternative splice isoforms, structures, regulation, and tissue and cell-type-specific functions, and propose that future mechanistic research integrating multiple A/B proteins will significantly improve our understanding of how this essential protein family contributes to cell homeostasis and disease.
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Affiliation(s)
- Patricia A. Thibault
- Office of the Saskatchewan Multiple Sclerosis Clinical Research Chair, University of Saskatchewan, Saskatoon, SK S7K 0M7, Canada; (P.A.T.); (J.-P.W.E.C.); (H.E.S.)
- Department of Medicine, Neurology Division, University of Saskatchewan, Saskatoon, SK S7N 0X8, Canada
| | - Aravindhan Ganesan
- ArGan’s Lab, School of Pharmacy, Faculty of Science, University of Waterloo, Waterloo, ON N2L 3G1, Canada;
| | - Subha Kalyaanamoorthy
- Department of Chemistry, Faculty of Science, University of Waterloo, Waterloo, ON N2L 3G1, Canada;
| | - Joseph-Patrick W. E. Clarke
- Office of the Saskatchewan Multiple Sclerosis Clinical Research Chair, University of Saskatchewan, Saskatoon, SK S7K 0M7, Canada; (P.A.T.); (J.-P.W.E.C.); (H.E.S.)
- Department of Health Sciences, College of Medicine, University of Saskatchewan, Saskatoon, SK S7N 5E5, Canada
- Department of Anatomy, Physiology and Pharmacology, University of Saskatchewan, Saskatoon, SK S7N 5E5, Canada
| | - Hannah E. Salapa
- Office of the Saskatchewan Multiple Sclerosis Clinical Research Chair, University of Saskatchewan, Saskatoon, SK S7K 0M7, Canada; (P.A.T.); (J.-P.W.E.C.); (H.E.S.)
- Department of Medicine, Neurology Division, University of Saskatchewan, Saskatoon, SK S7N 0X8, Canada
| | - Michael C. Levin
- Office of the Saskatchewan Multiple Sclerosis Clinical Research Chair, University of Saskatchewan, Saskatoon, SK S7K 0M7, Canada; (P.A.T.); (J.-P.W.E.C.); (H.E.S.)
- Department of Medicine, Neurology Division, University of Saskatchewan, Saskatoon, SK S7N 0X8, Canada
- Department of Health Sciences, College of Medicine, University of Saskatchewan, Saskatoon, SK S7N 5E5, Canada
- Department of Anatomy, Physiology and Pharmacology, University of Saskatchewan, Saskatoon, SK S7N 5E5, Canada
- Correspondence:
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9
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Liu X, Tian N, Huang Q, Xu Z, Cheng H, Liu X, Li D, Liang R, Li B, Dai X. hnRNPA1 enhances FOXP3 stability to promote the differentiation and functions of regulatory T cells. FEBS Lett 2021; 595:1962-1974. [PMID: 34080184 DOI: 10.1002/1873-3468.14142] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/01/2021] [Revised: 05/06/2021] [Accepted: 05/25/2021] [Indexed: 12/18/2022]
Abstract
Regulatory T cells (Tregs) are indispensable for the maintenance of immunological self-tolerance and homeostasis. Heterogeneous nuclear ribonucleoprotein A1 (hnRNPA1) is required for optimal Treg induction. Here, we reveal that human-induced Tregs (iTregs) lacking hnRNPA1 show reduced expression of the transcription factor FOXP3, increased ubiquitination level of FOXP3, and impaired suppressive abilities. Human naïve CD4 T cells with hnRNPA1 knockdown show a decreased Treg differentiation ratio. hnRNPA1 could interact with FOXP3 as well as with the E3 ligase Stub1. The phosphorylation at hnRNPA1 S199 could increase both interactions. The overexpression of FOXP3 in Tregs containing shhnRNPA1 could not recover the phenotype caused by hnRNPA1 knockdown. Therefore, there might be multiple essential pathways regulated by hnRNPA1 in Tregs. In conclusion, we present a new role of hnRNPA1 in promoting Treg function, indicating it as a promising target for tumor therapies.
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Affiliation(s)
- Xu Liu
- Shanghai Institute of Immunology & Department of Immunology and Microbiology, Shanghai Jiao Tong University School of Medicine, China
| | - Na Tian
- Department of Rheumatology and Immunology, Shanghai Jiao Tong University Affiliated Sixth People's Hospital, China
| | - Qianru Huang
- Shanghai Institute of Immunology & Department of Immunology and Microbiology, Shanghai Jiao Tong University School of Medicine, China
| | - Zhan Xu
- Shanghai Institute of Immunology & Department of Immunology and Microbiology, Shanghai Jiao Tong University School of Medicine, China
| | - Hao Cheng
- Shanghai Institute of Immunology & Department of Immunology and Microbiology, Shanghai Jiao Tong University School of Medicine, China
| | - Xinnan Liu
- Shanghai Institute of Immunology & Department of Immunology and Microbiology, Shanghai Jiao Tong University School of Medicine, China
| | - Dan Li
- Shanghai Institute of Immunology & Department of Immunology and Microbiology, Shanghai Jiao Tong University School of Medicine, China
| | - Rui Liang
- Shanghai Institute of Immunology & Department of Immunology and Microbiology, Shanghai Jiao Tong University School of Medicine, China
| | - Bin Li
- Shanghai Institute of Immunology & Department of Immunology and Microbiology, Shanghai Jiao Tong University School of Medicine, China
| | - Xueyu Dai
- Shanghai Institute of Immunology & Department of Immunology and Microbiology, Shanghai Jiao Tong University School of Medicine, China
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10
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van den Akker GGH, Zacchini F, Housmans BAC, van der Vloet L, Caron MMJ, Montanaro L, Welting TJM. Current Practice in Bicistronic IRES Reporter Use: A Systematic Review. Int J Mol Sci 2021; 22:5193. [PMID: 34068921 PMCID: PMC8156625 DOI: 10.3390/ijms22105193] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/25/2021] [Revised: 05/05/2021] [Accepted: 05/12/2021] [Indexed: 12/26/2022] Open
Abstract
Bicistronic reporter assays have been instrumental for transgene expression, understanding of internal ribosomal entry site (IRES) translation, and identification of novel cap-independent translational elements (CITE). We observed a large methodological variability in the use of bicistronic reporter assays and data presentation or normalization procedures. Therefore, we systematically searched the literature for bicistronic IRES reporter studies and analyzed methodological details, data visualization, and normalization procedures. Two hundred fifty-seven publications were identified using our search strategy (published 1994-2020). Experimental studies on eukaryotic adherent cell systems and the cell-free translation assay were included for further analysis. We evaluated the following methodological details for 176 full text articles: the bicistronic reporter design, the cell line or type, transfection methods, and time point of analyses post-transfection. For the cell-free translation assay, we focused on methods of in vitro transcription, type of translation lysate, and incubation times and assay temperature. Data can be presented in multiple ways: raw data from individual cistrons, a ratio of the two, or fold changes thereof. In addition, many different control experiments have been suggested when studying IRES-mediated translation. In addition, many different normalization and control experiments have been suggested when studying IRES-mediated translation. Therefore, we also categorized and summarized their use. Our unbiased analyses provide a representative overview of bicistronic IRES reporter use. We identified parameters that were reported inconsistently or incompletely, which could hamper data reproduction and interpretation. On the basis of our analyses, we encourage adhering to a number of practices that should improve transparency of bicistronic reporter data presentation and improve methodological descriptions to facilitate data replication.
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Affiliation(s)
- Guus Gijsbertus Hubert van den Akker
- Department of Orthopedic Surgery, Maastricht University, Medical Center+, 6229 ER Maastricht, The Netherlands; (G.G.H.v.d.A.); (B.A.C.H.); (L.v.d.V.); (M.M.J.C.)
| | - Federico Zacchini
- Department of Experimental, Diagnostic and Specialty Medicine, Bologna University, I-40138 Bologna, Italy; (F.Z.); (L.M.)
- Centro di Ricerca Biomedica Applicata—CRBA, Bologna University, Policlinico di Sant’Orsola, I-40138 Bologna, Italy
| | - Bas Adrianus Catharina Housmans
- Department of Orthopedic Surgery, Maastricht University, Medical Center+, 6229 ER Maastricht, The Netherlands; (G.G.H.v.d.A.); (B.A.C.H.); (L.v.d.V.); (M.M.J.C.)
| | - Laura van der Vloet
- Department of Orthopedic Surgery, Maastricht University, Medical Center+, 6229 ER Maastricht, The Netherlands; (G.G.H.v.d.A.); (B.A.C.H.); (L.v.d.V.); (M.M.J.C.)
| | - Marjolein Maria Johanna Caron
- Department of Orthopedic Surgery, Maastricht University, Medical Center+, 6229 ER Maastricht, The Netherlands; (G.G.H.v.d.A.); (B.A.C.H.); (L.v.d.V.); (M.M.J.C.)
| | - Lorenzo Montanaro
- Department of Experimental, Diagnostic and Specialty Medicine, Bologna University, I-40138 Bologna, Italy; (F.Z.); (L.M.)
- Centro di Ricerca Biomedica Applicata—CRBA, Bologna University, Policlinico di Sant’Orsola, I-40138 Bologna, Italy
- Programma Dipartimentale in Medicina di Laboratorio, IRCCS Azienda Ospedaliero-Universitaria di Bologna, Via Albertoni 15, I-40138 Bologna, Italy
| | - Tim Johannes Maria Welting
- Department of Orthopedic Surgery, Maastricht University, Medical Center+, 6229 ER Maastricht, The Netherlands; (G.G.H.v.d.A.); (B.A.C.H.); (L.v.d.V.); (M.M.J.C.)
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11
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Clarke JP, Thibault PA, Salapa HE, Levin MC. A Comprehensive Analysis of the Role of hnRNP A1 Function and Dysfunction in the Pathogenesis of Neurodegenerative Disease. Front Mol Biosci 2021; 8:659610. [PMID: 33912591 PMCID: PMC8072284 DOI: 10.3389/fmolb.2021.659610] [Citation(s) in RCA: 52] [Impact Index Per Article: 17.3] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/27/2021] [Accepted: 03/15/2021] [Indexed: 12/15/2022] Open
Abstract
Heterogeneous nuclear ribonucleoprotein A1 (hnRNP A1) is a member of the hnRNP family of conserved proteins that is involved in RNA transcription, pre-mRNA splicing, mRNA transport, protein translation, microRNA processing, telomere maintenance and the regulation of transcription factor activity. HnRNP A1 is ubiquitously, yet differentially, expressed in many cell types, and due to post-translational modifications, can vary in its molecular function. While a plethora of knowledge is known about the function and dysfunction of hnRNP A1 in diseases other than neurodegenerative disease (e.g., cancer), numerous studies in amyotrophic lateral sclerosis, frontotemporal lobar degeneration, multiple sclerosis, spinal muscular atrophy, Alzheimer’s disease, and Huntington’s disease have found that the dysregulation of hnRNP A1 may contribute to disease pathogenesis. How hnRNP A1 mechanistically contributes to these diseases, and whether mutations and/or altered post-translational modifications contribute to pathogenesis, however, is currently under investigation. The aim of this comprehensive review is to first describe the background of hnRNP A1, including its structure, biological functions in RNA metabolism and the post-translational modifications known to modify its function. With this knowledge, the review then describes the influence of hnRNP A1 in neurodegenerative disease, and how its dysfunction may contribute the pathogenesis.
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Affiliation(s)
- Joseph P Clarke
- Department of Health Sciences, College of Medicine, University of Saskatchewan, Saskatoon, SK, Canada.,Office of the Saskatchewan Multiple Sclerosis Clinical Research Chair, University of Saskatchewan, Saskatoon, SK, Canada
| | - Patricia A Thibault
- Office of the Saskatchewan Multiple Sclerosis Clinical Research Chair, University of Saskatchewan, Saskatoon, SK, Canada.,Division of Neurology, Department of Medicine, University of Saskatchewan, Saskatoon, SK, Canada
| | - Hannah E Salapa
- Office of the Saskatchewan Multiple Sclerosis Clinical Research Chair, University of Saskatchewan, Saskatoon, SK, Canada.,Division of Neurology, Department of Medicine, University of Saskatchewan, Saskatoon, SK, Canada
| | - Michael C Levin
- Department of Health Sciences, College of Medicine, University of Saskatchewan, Saskatoon, SK, Canada.,Office of the Saskatchewan Multiple Sclerosis Clinical Research Chair, University of Saskatchewan, Saskatoon, SK, Canada.,Division of Neurology, Department of Medicine, University of Saskatchewan, Saskatoon, SK, Canada.,Department of Anatomy, Physiology and Pharmacology, University of Saskatchewan, Saskatoon, SK, Canada
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12
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Depleting deubiquitinating enzymes promotes apoptosis in glioma cell line via RNA binding proteins SF2/ASF1. Biochem Biophys Rep 2020; 24:100846. [PMID: 33319070 PMCID: PMC7726668 DOI: 10.1016/j.bbrep.2020.100846] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/21/2020] [Revised: 10/22/2020] [Accepted: 10/27/2020] [Indexed: 12/13/2022] Open
Abstract
USP5 and USP8 (Deubiquitinating enzyme) are highly overexpressed and more recognized as poor prognosis marker in various cancers. Depleting USP5 or USP8 to assess the synergism with proteasome inhibitor (Bortezomib) were measured. Furthermore, in present finding USP5 cooperates hnRNPA1 & USP8 cooperate SF2/ASF1, therefore gain in expression of either hnRNPA1 or SF2/ASF1 is sufficient to promote cell survival. On the other side, apoptosis markers were more pronounced in U87 or T98G cells devoid of either USP5 or USP8. However, apparent increase in SF2/ASF1 in absence of USP5, providing resistant factor is new. Antiapoptotic activity due to rise in SF2/ASF1 was validated after co-knock down of SF2/ASF1 in addition to USP5 induces more apoptosis comparing to individual knock down of USP5 or SF2/ASF1. This reveals SF2/ASF1 (RNA binding protein) delayed the apoptotic effect due to loss of USP5, lends ubiquitination of hnRNPA1. In presence of USP5, PI3 kinase inhibition promotes even more interaction between USP5 and hnRNPA1, thereby stabilizes hnRNPA1 in U87MG. In that way hnRNPA1 and SF2/ASF1 impart oncogenic activity. In conclusion, siRNA based strategy against USP5 is not enough to inhibit glioma, moreover targeting additionally SF2/ASF1 by knocking down USP8 is suitably more effective to deal with glioma tumour reoccurrence by indirectly targeting both SF2/ASF1 and hnRNPA1 oncogene. Deubiquitinating enzyme USP5 interact with hnRNPA1 and promotes hnRNPA1 ubiquitination is PI3 Kinase dependent. USP5 knock down in glioma cell, stabilizes SF2/ASF1 expression act as resistance factor. Depleting SF2/ASF1 and USP5 synergistically promotes apoptosis in glioma cell.
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Barrera A, Ramos H, Vera-Otarola J, Fernández-García L, Angulo J, Olguín V, Pino K, Mouland AJ, López-Lastra M. Post-translational modifications of hnRNP A1 differentially modulate retroviral IRES-mediated translation initiation. Nucleic Acids Res 2020; 48:10479-10499. [PMID: 32960212 PMCID: PMC7544202 DOI: 10.1093/nar/gkaa765] [Citation(s) in RCA: 19] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/22/2019] [Revised: 08/09/2020] [Accepted: 09/02/2020] [Indexed: 12/20/2022] Open
Abstract
The full-length mRNAs of the human immunodeficiency virus type-1 (HIV-1), the human T-cell lymphotropic virus type-1 (HTLV-1), and the mouse mammary tumor virus (MMTV) harbor IRESs. The activity of the retroviral-IRESs requires IRES-transacting factors (ITAFs), being hnRNP A1, a known ITAF for the HIV-1 IRES. In this study, we show that hnRNP A1 is also an ITAF for the HTLV-1 and MMTV IRESs. The MMTV IRES proved to be more responsive to hnRNP A1 than either the HTLV-1 or the HIV-1 IRESs. The impact of post-translational modifications of hnRNP A1 on HIV-1, HTLV-1 and MMTV IRES activity was also assessed. Results show that the HIV-1 and HTLV-1 IRESs were equally responsive to hnRNP A1 and its phosphorylation mutants S4A/S6A, S4D/S6D and S199A/D. However, the S4D/S6D mutant stimulated the activity from the MMTV-IRES to levels significantly higher than the wild type hnRNP A1. PRMT5-induced symmetrical di-methylation of arginine residues of hnRNP A1 enabled the ITAF to stimulate the HIV-1 and HTLV-1 IRESs while reducing the stimulatory ability of the ITAF over the MMTV IRES. We conclude that retroviral IRES activity is not only dependent on the recruited ITAFs but also relies on how these proteins are modified at the post-translational level.
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Affiliation(s)
- Aldo Barrera
- Laboratorio de Virología Molecular, Instituto Milenio de Inmunología e Inmunoterapia, Departamento de Enfermedades Infecciosas e Inmunología Pediátrica, Escuela de Medicina, Pontificia Universidad Católica de Chile, Marcoleta 391, Santiago, Chile
| | - Hade Ramos
- Laboratorio de Virología Molecular, Instituto Milenio de Inmunología e Inmunoterapia, Departamento de Enfermedades Infecciosas e Inmunología Pediátrica, Escuela de Medicina, Pontificia Universidad Católica de Chile, Marcoleta 391, Santiago, Chile
| | - Jorge Vera-Otarola
- Laboratorio de Virología Molecular, Instituto Milenio de Inmunología e Inmunoterapia, Departamento de Enfermedades Infecciosas e Inmunología Pediátrica, Escuela de Medicina, Pontificia Universidad Católica de Chile, Marcoleta 391, Santiago, Chile
| | - Leandro Fernández-García
- Laboratorio de Virología Molecular, Instituto Milenio de Inmunología e Inmunoterapia, Departamento de Enfermedades Infecciosas e Inmunología Pediátrica, Escuela de Medicina, Pontificia Universidad Católica de Chile, Marcoleta 391, Santiago, Chile
| | - Jenniffer Angulo
- Laboratorio de Virología Molecular, Instituto Milenio de Inmunología e Inmunoterapia, Departamento de Enfermedades Infecciosas e Inmunología Pediátrica, Escuela de Medicina, Pontificia Universidad Católica de Chile, Marcoleta 391, Santiago, Chile
| | - Valeria Olguín
- Laboratorio de Virología Molecular, Instituto Milenio de Inmunología e Inmunoterapia, Departamento de Enfermedades Infecciosas e Inmunología Pediátrica, Escuela de Medicina, Pontificia Universidad Católica de Chile, Marcoleta 391, Santiago, Chile
| | - Karla Pino
- Laboratorio de Virología Molecular, Instituto Milenio de Inmunología e Inmunoterapia, Departamento de Enfermedades Infecciosas e Inmunología Pediátrica, Escuela de Medicina, Pontificia Universidad Católica de Chile, Marcoleta 391, Santiago, Chile
| | - Andrew J Mouland
- HIV-1 RNA Trafficking Laboratory, Lady Davis Institute at the Jewish General Hospital, Montréal, Québec H3T 1E2, Canada
- Department of Medicine, McGill University, Montréal, Québec H4A 3J1, Canada
| | - Marcelo López-Lastra
- Laboratorio de Virología Molecular, Instituto Milenio de Inmunología e Inmunoterapia, Departamento de Enfermedades Infecciosas e Inmunología Pediátrica, Escuela de Medicina, Pontificia Universidad Católica de Chile, Marcoleta 391, Santiago, Chile
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Barrera A, Olguín V, Vera-Otarola J, López-Lastra M. Cap-independent translation initiation of the unspliced RNA of retroviruses. BIOCHIMICA ET BIOPHYSICA ACTA-GENE REGULATORY MECHANISMS 2020; 1863:194583. [PMID: 32450258 DOI: 10.1016/j.bbagrm.2020.194583] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Subscribe] [Scholar Register] [Received: 04/08/2020] [Revised: 05/12/2020] [Accepted: 05/18/2020] [Indexed: 12/12/2022]
Abstract
Retroviruses are a unique family of RNA viruses that utilize a virally encoded reverse transcriptase (RT) to replicate their genomic RNA (gRNA) through a proviral DNA intermediate. The provirus is permanently integrated into the host cell chromosome and is expressed by the host cell transcription, RNA processing, and translation machinery. Retroviral messenger RNAs (mRNAs) entirely resemble a cellular mRNA as they have a 5'cap structure, 5'untranslated region (UTR), an open reading frame (ORF), 3'UTR, and a 3'poly(A) tail. The primary transcription product interacts with the cellular RNA processing machinery and is spliced, exported to the cytoplasm, and translated. However, a proportion of the pre-mRNA subverts typical RNA processing giving rise to the full-length RNA. In the cytoplasm, the full-length retroviral RNA fulfills a dual role acting as mRNA and as the gRNA. Simple retroviruses generate two pools of full-length RNA, one for each purpose. However, complex retroviruses have a single pool of full-length RNA, which is destined for translation or encapsidation. As for eukaryotic mRNAs, translational control of retroviral protein synthesis is mostly exerted at the step of initiation. Interestingly, some retroviral mRNAs, both simple and complex, use a dual mechanism to initiate protein synthesis, a cap-dependent initiation mechanism, or via internal initiation using an internal ribosome entry site (IRES). In this review, we describe and discuss data regarding the molecular mechanism driving the canonical cap-dependent and IRES-mediated translation initiation for retroviral mRNA, focusing the discussion mainly on the most studied retroviral mRNA, the HIV-1 mRNA.
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Affiliation(s)
- Aldo Barrera
- Laboratorio de Virología Molecular, Instituto Milenio de Inmunología e Inmunoterapia, Centro de Investigaciones Médicas, Departamento de Enfermedades Infecciosas e Inmunología Pediátrica, Escuela de Medicina, Pontificia Universidad Católica de Chile, Marcoleta 391, Santiago, Chile
| | - Valeria Olguín
- Laboratorio de Virología Molecular, Instituto Milenio de Inmunología e Inmunoterapia, Centro de Investigaciones Médicas, Departamento de Enfermedades Infecciosas e Inmunología Pediátrica, Escuela de Medicina, Pontificia Universidad Católica de Chile, Marcoleta 391, Santiago, Chile
| | - Jorge Vera-Otarola
- Laboratorio de Virología Molecular, Instituto Milenio de Inmunología e Inmunoterapia, Centro de Investigaciones Médicas, Departamento de Enfermedades Infecciosas e Inmunología Pediátrica, Escuela de Medicina, Pontificia Universidad Católica de Chile, Marcoleta 391, Santiago, Chile
| | - Marcelo López-Lastra
- Laboratorio de Virología Molecular, Instituto Milenio de Inmunología e Inmunoterapia, Centro de Investigaciones Médicas, Departamento de Enfermedades Infecciosas e Inmunología Pediátrica, Escuela de Medicina, Pontificia Universidad Católica de Chile, Marcoleta 391, Santiago, Chile.
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Benavides-Serrato A, Saunders JT, Holmes B, Nishimura RN, Lichtenstein A, Gera J. Repurposing Potential of Riluzole as an ITAF Inhibitor in mTOR Therapy Resistant Glioblastoma. Int J Mol Sci 2020; 21:ijms21010344. [PMID: 31948038 PMCID: PMC6981868 DOI: 10.3390/ijms21010344] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/12/2019] [Revised: 12/27/2019] [Accepted: 12/31/2019] [Indexed: 12/17/2022] Open
Abstract
Internal ribosome entry site (IRES)-mediated protein synthesis has been demonstrated to play an important role in resistance to mechanistic target of rapamycin (mTOR) targeted therapies. Previously, we have demonstrated that the IRES trans-acting factor (ITAF), hnRNP A1 is required to promote IRES activity and small molecule inhibitors which bind specifically to this ITAF and curtail IRES activity, leading to mTOR inhibitor sensitivity. Here we report the identification of riluzole (Rilutek®), an FDA-approved drug for amyotrophic lateral sclerosis (ALS), via an in silico docking analysis of FDA-approved compounds, as an inhibitor of hnRNP A1. In a riluzole-bead coupled binding assay and in surface plasmon resonance imaging analyses, riluzole was found to directly bind to hnRNP A1 and inhibited IRES activity via effects on ITAF/RNA-binding. Riluzole also demonstrated synergistic anti-glioblastoma (GBM) affects with mTOR inhibitors in vitro and in GBM xenografts in mice. These data suggest that repurposing riluzole, used in conjunction with mTOR inhibitors, may serve as an effective therapeutic option in glioblastoma.
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Affiliation(s)
- Angelica Benavides-Serrato
- Department of Research & Development, Greater Los Angeles Veterans Affairs Healthcare System, Los Angeles, CA 91343, USA
| | - Jacquelyn T. Saunders
- Department of Research & Development, Greater Los Angeles Veterans Affairs Healthcare System, Los Angeles, CA 91343, USA
| | - Brent Holmes
- Department of Research & Development, Greater Los Angeles Veterans Affairs Healthcare System, Los Angeles, CA 91343, USA
| | - Robert N. Nishimura
- Department of Research & Development, Greater Los Angeles Veterans Affairs Healthcare System, Los Angeles, CA 91343, USA
- Department of Neurology, David Geffen School of Medicine at UCLA, Los Angeles, CA 90095, USA
| | - Alan Lichtenstein
- Department of Research & Development, Greater Los Angeles Veterans Affairs Healthcare System, Los Angeles, CA 91343, USA
- Jonnson Comprehensive Cancer Center, University of California-Los Angeles, Los Angeles, CA 90095, USA
- Department of Medicine, David Geffen School of Medicine at UCLA, Los Angeles, CA 90095, USA
| | - Joseph Gera
- Department of Research & Development, Greater Los Angeles Veterans Affairs Healthcare System, Los Angeles, CA 91343, USA
- Jonnson Comprehensive Cancer Center, University of California-Los Angeles, Los Angeles, CA 90095, USA
- Department of Medicine, David Geffen School of Medicine at UCLA, Los Angeles, CA 90095, USA
- Molecular Biology Institute, University of California-Los Angeles, Los Angeles, CA 90095, USA
- Correspondence: ; Tel.: +00-1-818-895-9416
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Marina D, Arnaud L, Paul Noel L, Felix S, Bernard R, Natacha C. Relevance of Translation Initiation in Diffuse Glioma Biology and its Therapeutic Potential. Cells 2019; 8:E1542. [PMID: 31795417 PMCID: PMC6953081 DOI: 10.3390/cells8121542] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/18/2019] [Revised: 11/21/2019] [Accepted: 11/26/2019] [Indexed: 02/06/2023] Open
Abstract
Cancer cells are continually exposed to environmental stressors forcing them to adapt their protein production to survive. The translational machinery can be recruited by malignant cells to synthesize proteins required to promote their survival, even in times of high physiological and pathological stress. This phenomenon has been described in several cancers including in gliomas. Abnormal regulation of translation has encouraged the development of new therapeutics targeting the protein synthesis pathway. This approach could be meaningful for glioma given the fact that the median survival following diagnosis of the highest grade of glioma remains short despite current therapy. The identification of new targets for the development of novel therapeutics is therefore needed in order to improve this devastating overall survival rate. This review discusses current literature on translation in gliomas with a focus on the initiation step covering both the cap-dependent and cap-independent modes of initiation. The different translation initiation protagonists will be described in normal conditions and then in gliomas. In addition, their gene expression in gliomas will systematically be examined using two freely available datasets. Finally, we will discuss different pathways regulating translation initiation and current drugs targeting the translational machinery and their potential for the treatment of gliomas.
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Affiliation(s)
- Digregorio Marina
- Laboratory of Nervous System Disorders and Therapy, GIGA-Neurosciences Research Centre, University of Liège, 4000 Liège, Belgium; (D.M.); (L.A.); (L.P.N.); (S.F.); (R.B.)
| | - Lombard Arnaud
- Laboratory of Nervous System Disorders and Therapy, GIGA-Neurosciences Research Centre, University of Liège, 4000 Liège, Belgium; (D.M.); (L.A.); (L.P.N.); (S.F.); (R.B.)
- Department of Neurosurgery, CHU of Liège, 4000 Liège, Belgium
| | - Lumapat Paul Noel
- Laboratory of Nervous System Disorders and Therapy, GIGA-Neurosciences Research Centre, University of Liège, 4000 Liège, Belgium; (D.M.); (L.A.); (L.P.N.); (S.F.); (R.B.)
| | - Scholtes Felix
- Laboratory of Nervous System Disorders and Therapy, GIGA-Neurosciences Research Centre, University of Liège, 4000 Liège, Belgium; (D.M.); (L.A.); (L.P.N.); (S.F.); (R.B.)
- Department of Neurosurgery, CHU of Liège, 4000 Liège, Belgium
| | - Rogister Bernard
- Laboratory of Nervous System Disorders and Therapy, GIGA-Neurosciences Research Centre, University of Liège, 4000 Liège, Belgium; (D.M.); (L.A.); (L.P.N.); (S.F.); (R.B.)
- Department of Neurology, CHU of Liège, 4000 Liège, Belgium
| | - Coppieters Natacha
- Laboratory of Nervous System Disorders and Therapy, GIGA-Neurosciences Research Centre, University of Liège, 4000 Liège, Belgium; (D.M.); (L.A.); (L.P.N.); (S.F.); (R.B.)
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The protein arginine methyltransferase PRMT5 confers therapeutic resistance to mTOR inhibition in glioblastoma. J Neurooncol 2019; 145:11-22. [PMID: 31473880 DOI: 10.1007/s11060-019-03274-0] [Citation(s) in RCA: 34] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/03/2019] [Accepted: 08/24/2019] [Indexed: 12/11/2022]
Abstract
INTRODUCTION Clinical trials directed at mechanistic target of rapamycin (mTOR) inhibition have yielded disappointing results in glioblastoma (GBM). A major mechanism of resistance involves the activation of a salvage pathway stimulating internal ribosome entry site (IRES)-mediated protein synthesis. PRMT5 activity has been implicated in the enhancement of IRES activity. METHODS We analyzed the expression and activity of PRMT5 in response to mTOR inhibition in GBM cell lines and short-term patient cultures. To determine whether PRMT5 conferred resistance we used genetic and pharmacological approaches to ablate PRMT5 activity and assessed the effects on in vitro and in vivo sensitivity. Mutational analyses of the requisite IRES-trans-acting factor (ITAF), hnRNP A1 determined whether PRMT5-mediated methylation was necessary for ITAF RNA binding and IRES activity. RESULTS PRMT5 activity is stimulated in response to mTOR inhibitors. Knockdown or treatment with a PRMT5 inhibitor blocked IRES activity and sensitizes GBM cells. Ectopic expression of non-methylatable hnRNP A1 mutants demonstrated that methylation of either arginine residues 218 or 225 was sufficient to maintain IRES binding and hnRNP A1-dependent cyclin D1 or c-MYC IRES activity, however a double R218K/R225K mutant was unable to do so. The PRMT5 inhibitor EPZ015666 displayed synergistic anti-GBM effects in vitro and in a xenograft mouse model in combination with PP242. CONCLUSIONS These results demonstrate that PRMT5 activity is stimulated upon mTOR inhibition in GBM. Our data further support a signaling cascade in which PRMT5-mediated methylation of hnRNP A1 promotes IRES RNA binding and activation of IRES-mediated protein synthesis and resultant mTOR inhibitor resistance.
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Delaidelli A, Jan A, Herms J, Sorensen PH. Translational control in brain pathologies: biological significance and therapeutic opportunities. Acta Neuropathol 2019; 137:535-555. [PMID: 30739199 DOI: 10.1007/s00401-019-01971-8] [Citation(s) in RCA: 20] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/25/2018] [Revised: 01/30/2019] [Accepted: 02/04/2019] [Indexed: 12/13/2022]
Abstract
Messenger RNA (mRNA) translation is the terminal step in protein synthesis, providing a crucial regulatory checkpoint for this process. Translational control allows specific cell types to respond to rapid changes in the microenvironment or to serve specific functions. For example, neurons use mRNA transport to achieve local protein synthesis at significant distances from the nucleus, the site of RNA transcription. Altered expression or functions of the various components of the translational machinery have been linked to several pathologies in the central nervous system. In this review, we provide a brief overview of the basic principles of mRNA translation, and discuss alterations of this process relevant to CNS disease conditions, with a focus on brain tumors and chronic neurological conditions. Finally, synthesizing this knowledge, we discuss the opportunities to exploit the biology of altered mRNA translation for novel therapies in brain disorders, as well as how studying these alterations can shed new light on disease mechanisms.
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Affiliation(s)
- Alberto Delaidelli
- Department of Molecular Oncology, British Columbia Cancer Research Centre, Vancouver, BC, V5Z 1L3, Canada.
- Department of Pathology and Laboratory Medicine, University of British Columbia, Vancouver, BC, V6T 1Z3, Canada.
| | - Asad Jan
- Department of Biomedicine, Aarhus Institute of Advanced Studies, Aarhus University, Høegh-Guldbergs Gade 6B, 8000, Aarhus C, Denmark
| | - Jochen Herms
- Department for Translational Brain Research, German Center for Neurodegenerative Diseases (DZNE), Munich, Germany
- Center for Neuropathology and Prion Research, Ludwig-Maximilians-University, Munich, Germany
- Munich Cluster of Systems Neurology (SyNergy), Ludwig-Maximilians-University Munich, Schillerstraße 44, 80336, Munich, Germany
| | - Poul H Sorensen
- Department of Molecular Oncology, British Columbia Cancer Research Centre, Vancouver, BC, V5Z 1L3, Canada.
- Department of Pathology and Laboratory Medicine, University of British Columbia, Vancouver, BC, V6T 1Z3, Canada.
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Levengood JD, Tolbert BS. Idiosyncrasies of hnRNP A1-RNA recognition: Can binding mode influence function. Semin Cell Dev Biol 2019; 86:150-161. [PMID: 29625167 PMCID: PMC6177329 DOI: 10.1016/j.semcdb.2018.04.001] [Citation(s) in RCA: 21] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/15/2018] [Revised: 03/27/2018] [Accepted: 04/03/2018] [Indexed: 12/21/2022]
Abstract
The heterogeneous nuclear ribonucleoproteins (hnRNPs) are a diverse family of RNA binding proteins that function in most stages of RNA metabolism. The prototypical member, hnRNP A1, is composed of three major domains; tandem N-terminal RNA Recognition Motifs (RRMs) and a C-terminal mostly intrinsically disordered region. HnRNP A1 is broadly implicated in basic cellular RNA processing events such as splicing, stability, nuclear export and translation. Due to its ubiquity and abundance, hnRNP A1 is also frequently usurped to control viral gene expression. Deregulation of the RNA metabolism functions of hnRNP A1 in neuronal cells contributes to several neurodegenerative disorders. Because of these roles in human pathologies, the study of hnRNP A1 provides opportunities for the development of novel therapeutics, with disruption of its RNA binding capabilities being the most promising target. The functional diversity of hnRNP A1 is reflected in the complex nature by which it interacts with various RNA targets. Indeed, hnRNP A1 binds both structured and unstructured RNAs with binding affinities that span several magnitudes. Available structures of hnRNP A1-RNA complexes also suggest a degree of plasticity in molecular recognition. Given the reinvigoration in hnRNP A1, the goal of this review is to use the available structural biochemical developments as a framework to interpret its wide-range of RNA functions.
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Affiliation(s)
- Jeffrey D Levengood
- Department of Chemistry, Case Western Reserve University, Cleveland, OH, United States
| | - Blanton S Tolbert
- Department of Chemistry, Case Western Reserve University, Cleveland, OH, United States.
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20
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Roy R, Huang Y, Seckl MJ, Pardo OE. Emerging roles of hnRNPA1 in modulating malignant transformation. WILEY INTERDISCIPLINARY REVIEWS-RNA 2017; 8. [PMID: 28791797 DOI: 10.1002/wrna.1431] [Citation(s) in RCA: 53] [Impact Index Per Article: 7.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/01/2017] [Revised: 05/19/2017] [Accepted: 05/22/2017] [Indexed: 01/05/2023]
Abstract
Heterogeneous nuclear ribonucleoproteins (hnRNPs) are RNA-binding proteins associated with complex and diverse biological processes such as processing of heterogeneous nuclear RNAs (hnRNAs) into mature mRNAs, RNA splicing, transactivation of gene expression, and modulation of protein translation. hnRNPA1 is the most abundant and ubiquitously expressed member of this protein family and has been shown to be involved in multiple molecular events driving malignant transformation. In addition to selective mRNA splicing events promoting expression of specific protein variants, hnRNPA1 regulates the gene expression and translation of several key players associated with tumorigenesis and cancer progression. Here, we will summarize our current knowledge of the involvement of hnRNPA1 in cancer, including its roles in regulating cell proliferation, invasiveness, metabolism, adaptation to stress and immortalization. WIREs RNA 2017, 8:e1431. doi: 10.1002/wrna.1431 For further resources related to this article, please visit the WIREs website.
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Affiliation(s)
- Rajat Roy
- Division of Cancer, Department of Surgery and Cancer, Imperial College London, London, UK
| | - Yueyang Huang
- Division of Cancer, Department of Surgery and Cancer, Imperial College London, London, UK
| | - Michael J Seckl
- Division of Cancer, Department of Surgery and Cancer, Imperial College London, London, UK
| | - Olivier E Pardo
- Division of Cancer, Department of Surgery and Cancer, Imperial College London, London, UK
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21
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Holmes B, Lee J, Landon KA, Benavides-Serrato A, Bashir T, Jung ME, Lichtenstein A, Gera J. Mechanistic Target of Rapamycin (mTOR) Inhibition Synergizes with Reduced Internal Ribosome Entry Site (IRES)-mediated Translation of Cyclin D1 and c-MYC mRNAs to Treat Glioblastoma. J Biol Chem 2016; 291:14146-14159. [PMID: 27226604 DOI: 10.1074/jbc.m116.726927] [Citation(s) in RCA: 38] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/11/2016] [Indexed: 12/18/2022] Open
Abstract
Our previous work has demonstrated an intrinsic mRNA-specific protein synthesis salvage pathway operative in glioblastoma (GBM) tumor cells that is resistant to mechanistic target of rapamycin (mTOR) inhibitors. The activation of this internal ribosome entry site (IRES)-dependent mRNA translation initiation pathway results in continued translation of critical transcripts involved in cell cycle progression in the face of global eIF-4E-mediated translation inhibition. Recently we identified compound 11 (C11), a small molecule capable of inhibiting c-MYC IRES translation as a consequence of blocking the interaction of a requisite c-MYC IRES trans-acting factor, heterogeneous nuclear ribonucleoprotein A1, with its IRES. Here we demonstrate that C11 also blocks cyclin D1 IRES-dependent initiation and demonstrates synergistic anti-GBM properties when combined with the mechanistic target of rapamycin kinase inhibitor PP242. The structure-activity relationship of C11 was investigated and resulted in the identification of IRES-J007, which displayed improved IRES-dependent initiation blockade and synergistic anti-GBM effects with PP242. Mechanistic studies with C11 and IRES-J007 revealed binding of the inhibitors within the UP1 fragment of heterogeneous nuclear ribonucleoprotein A1, and docking analysis suggested a small pocket within close proximity to RRM2 as the potential binding site. We further demonstrate that co-therapy with IRES-J007 and PP242 significantly reduces tumor growth of GBM xenografts in mice and that combined inhibitor treatments markedly reduce the mRNA translational state of cyclin D1 and c-MYC transcripts in these tumors. These data support the combined use of IRES-J007 and PP242 to achieve synergistic antitumor responses in GBM.
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Affiliation(s)
- Brent Holmes
- Department of Medicine, David Geffen School of Medicine, University of California, Los Angeles, California 90048; Department of Research and Development, Greater Los Angeles Veterans Affairs Healthcare System, Los Angeles, California 91343
| | - Jihye Lee
- Department of Chemistry and Biochemistry, University of California, Los Angeles, California 90048
| | - Kenna A Landon
- Department of Research and Development, Greater Los Angeles Veterans Affairs Healthcare System, Los Angeles, California 91343
| | - Angelica Benavides-Serrato
- Department of Research and Development, Greater Los Angeles Veterans Affairs Healthcare System, Los Angeles, California 91343
| | - Tariq Bashir
- Department of Research and Development, Greater Los Angeles Veterans Affairs Healthcare System, Los Angeles, California 91343
| | - Michael E Jung
- Department of Chemistry and Biochemistry, University of California, Los Angeles, California 90048; Jonnson Comprehensive Cancer Center, University of California, Los Angeles, California 90048; Molecular Biology Institute, University of California, Los Angeles, California 90048
| | - Alan Lichtenstein
- Department of Medicine, David Geffen School of Medicine, University of California, Los Angeles, California 90048; Department of Research and Development, Greater Los Angeles Veterans Affairs Healthcare System, Los Angeles, California 91343; Jonnson Comprehensive Cancer Center, University of California, Los Angeles, California 90048
| | - Joseph Gera
- Department of Medicine, David Geffen School of Medicine, University of California, Los Angeles, California 90048; Department of Research and Development, Greater Los Angeles Veterans Affairs Healthcare System, Los Angeles, California 91343; Jonnson Comprehensive Cancer Center, University of California, Los Angeles, California 90048; Molecular Biology Institute, University of California, Los Angeles, California 90048.
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sST2 translation is regulated by FGF2 via an hnRNP A1-mediated IRES-dependent mechanism. BIOCHIMICA ET BIOPHYSICA ACTA-GENE REGULATORY MECHANISMS 2016; 1859:848-59. [PMID: 27168114 DOI: 10.1016/j.bbagrm.2016.05.005] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Subscribe] [Scholar Register] [Received: 11/23/2015] [Revised: 04/15/2016] [Accepted: 05/05/2016] [Indexed: 11/23/2022]
Abstract
Translation is an energy-intensive process and tightly regulated. Generally, translation is initiated in a cap-dependent manner. Under stress conditions, typically found within the tumor microenvironment in association with e.g. nutrient deprivation or hypoxia, cap-dependent translation decreases, and alternative modes of translation initiation become more important. Specifically, internal ribosome entry sites (IRES) facilitate translation of specific mRNAs under otherwise translation-inhibitory conditions. This mechanism is controlled by IRES trans-acting factors (ITAF), i.e. by RNA-binding proteins, which interact with and determine the activity of selected IRESs. We aimed at characterizing the translational regulation of the IL-33 decoy receptor sST2, which was enhanced by fibroblast growth factor 2 (FGF2). We identified and verified an IRES within the 5'UTR of sST2. Furthermore, we found that MEK/ERK signaling contributes to FGF2-induced, sST2-IRES activation and translation. Determination of the sST2-5'UTR structure by in-line probing followed by deletion analyses identified 23 nucleotides within the sST2-5'UTR to be required for optimal IRES activity. Finally, we show that the RNA-binding protein heterogeneous ribonucleoprotein A1 (hnRNP A1) binds to the sST2-5'UTR, acts as an ITAF, and thus controls the activity of the sST2-IRES and consequently sST2 translation. Specifically, FGF2 enhances nuclear-cytoplasmic translocation of hnRNP A1, which requires intact MEK/ERK activity. In summary, we provide evidence that the sST2-5'UTR contains an IRES element, which is activated by a MEK/ERK-dependent increase in cytoplasmic localization of hnRNP A1 in response to FGF2, enhancing the translation of sST2.
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Roy R, Durie D, Li H, Liu BQ, Skehel JM, Mauri F, Cuorvo LV, Barbareschi M, Guo L, Holcik M, Seckl MJ, Pardo OE. hnRNPA1 couples nuclear export and translation of specific mRNAs downstream of FGF-2/S6K2 signalling. Nucleic Acids Res 2014; 42:12483-97. [PMID: 25324306 PMCID: PMC4227786 DOI: 10.1093/nar/gku953] [Citation(s) in RCA: 65] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/15/2014] [Revised: 09/26/2014] [Accepted: 09/29/2014] [Indexed: 01/14/2023] Open
Abstract
The increased cap-independent translation of anti-apoptotic proteins is involved in the development of drug resistance in lung cancer but signalling events regulating this are poorly understood. Fibroblast growth factor 2 (FGF-2) signalling-induced S6 kinase 2 (S6K2) activation is necessary, but the downstream mediator(s) coupling this kinase to the translational response is unknown. Here, we show that S6K2 binds and phosphorylates hnRNPA1 on novel Ser4/6 sites, increasing its association with BCL-XL and XIAP mRNAs to promote their nuclear export. In the cytoplasm, phosphoS4/6-hnRNPA1 dissociates from these mRNAs de-repressing their IRES-mediated translation. This correlates with the phosphorylation-dependent association of hnRNPA1 with 14-3-3 leading to hnRNPA1 sumoylation on K183 and its re-import into the nucleus. A non-phosphorylatible, S4/6A mutant prevented these processes, hindering the pro-survival activity of FGF-2/S6K2 signalling. Interestingly, immunohistochemical staining of lung and breast cancer tissue samples demonstrated that increased S6K2 expression correlates with decreased cytoplasmic hnRNPA1 and increased BCL-XL expression. In short, phosphorylation on novel N-term sites of hnRNPA1 promotes translation of anti-apoptotic proteins and is indispensable for the pro-survival effects of FGF-2.
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Affiliation(s)
- Rajat Roy
- Division of Cancer, Department of Surgery and Cancer, 1st Floor, ICTEM Building, Hammersmith Hospitals Campus of Imperial College London, Du Cane Road, London W12 0NN, UK
| | - Danielle Durie
- Apoptosis Research Centre, Children's Hospital of Eastern Ontario Research Institute, Ottawa, Ontario, Canada
| | - Hui Li
- Department of Biochemistry, Wuhan University, Wuhan, China
| | - Bing-Qian Liu
- Department of Biochemistry, Wuhan University, Wuhan, China
| | - John Mark Skehel
- Protein Analysis and Proteomics Laboratory, London Research Institute, South Mimms, EN6 3LD, UK
| | - Francesco Mauri
- Department of Histopathology, Hammersmith Hospital Campus, Imperial College, London W120NN, UK
| | | | | | - Lin Guo
- Department of Biochemistry, Wuhan University, Wuhan, China
| | - Martin Holcik
- Apoptosis Research Centre, Children's Hospital of Eastern Ontario Research Institute, Ottawa, Ontario, Canada
| | - Michael J Seckl
- Division of Cancer, Department of Surgery and Cancer, 1st Floor, ICTEM Building, Hammersmith Hospitals Campus of Imperial College London, Du Cane Road, London W12 0NN, UK
| | - Olivier E Pardo
- Division of Cancer, Department of Surgery and Cancer, 1st Floor, ICTEM Building, Hammersmith Hospitals Campus of Imperial College London, Du Cane Road, London W12 0NN, UK
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Jean-Philippe J, Paz S, Caputi M. hnRNP A1: the Swiss army knife of gene expression. Int J Mol Sci 2013; 14:18999-9024. [PMID: 24065100 PMCID: PMC3794818 DOI: 10.3390/ijms140918999] [Citation(s) in RCA: 207] [Impact Index Per Article: 18.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/12/2013] [Revised: 09/02/2013] [Accepted: 09/04/2013] [Indexed: 12/31/2022] Open
Abstract
Eukaryotic cells express a large variety of RNA binding proteins (RBPs), with diverse affinities and specificities towards target RNAs. These proteins play a crucial role in almost every aspect of RNA biogenesis, expression and function. The heterogeneous nuclear ribonucleoproteins (hnRNPs) are a complex and diverse family of RNA binding proteins. hnRNPs display multiple functions in the processing of heterogeneous nuclear RNAs into mature messenger RNAs. hnRNP A1 is one of the most abundant and ubiquitously expressed members of this protein family. hnRNP A1 plays multiple roles in gene expression by regulating major steps in the processing of nascent RNA transcripts. The transcription, splicing, stability, export through nuclear pores and translation of cellular and viral transcripts are all mechanisms modulated by this protein. The diverse functions played by hnRNP A1 are not limited to mRNA biogenesis, but extend to the processing of microRNAs, telomere maintenance and the regulation of transcription factor activity. Genomic approaches have recently uncovered the extent of hnRNP A1 roles in the development and differentiation of living organisms. The aim of this review is to highlight recent developments in the study of this protein and to describe its functions in cellular and viral gene expression and its role in human pathologies.
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Affiliation(s)
- Jacques Jean-Philippe
- Charles E. Schmidt College of Medicine, Florida Atlantic University, 777 Glades Rd, Boca Raton, FL 33431, USA.
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Cloninger C, Bernath A, Bashir T, Holmes B, Artinian N, Ruegg T, Anderson L, Masri J, Lichtenstein A, Gera J. Inhibition of SAPK2/p38 enhances sensitivity to mTORC1 inhibition by blocking IRES-mediated translation initiation in glioblastoma. Mol Cancer Ther 2011; 10:2244-56. [PMID: 21911485 DOI: 10.1158/1535-7163.mct-11-0478] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
A variety of mechanisms confer hypersensitivity of tumor cells to the macrolide rapamycin, the prototypic mTORC1 inhibitor. Several studies have shown that the status of the AKT kinase plays a critical role in determining hypersensitivity. Cancer cells in which AKT activity is elevated are exquisitely sensitive to mTORC1 inhibitors while cells in which the kinase is quiescent are relatively resistant. Our previous work has shown that a transcript-specific protein synthesis salvage pathway is operative in cells with quiescent AKT levels, maintaining the translation of crucial mRNAs involved in cell-cycle progression in the face of global eIF-4E-mediated translation inhibition. The activation of this salvage pathway is dependent on SAPK2/p38-mediated activation of IRES-dependent initiation of the cyclin D1 and c-MYC mRNAs, resulting in the maintenance of their protein expression levels. Here, we show that both genetic and pharmacologic inhibition of SAPK2/p38 in glioblastoma multiforme cells significantly reduces rapamycin-induced IRES-mediated translation initiation of cyclin D1 and c-MYC, resulting in increased G(1) arrest in vitro and inhibition of tumor growth in xenografts. Moreover, we observed that the AKT-dependent signaling alterations seen in vitro are also displayed in engrafted tumors cells and were able to show that combined inhibitor treatments markedly reduced the mRNA translational state of cyclin D1 and c-MYC transcripts in tumors isolated from mice. These data support the combined use of SAPK2/p38 and mTORC1 inhibitors to achieve a synergistic antitumor therapeutic response, particularly in rapamycin-resistant quiescent AKT-containing cells.
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Affiliation(s)
- Cheri Cloninger
- Department of Research & Development, Greater Los Angeles VA Healthcare System, 16111 Plummer Street (151), Sepulveda, CA 91343, USA
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