1
|
The E3 Ligase TRIM25 Impairs Apoptotic Cell Death in Colon Carcinoma Cells via Destabilization of Caspase-7 mRNA: A Possible Role of hnRNPH1. Cells 2023; 12:cells12010201. [PMID: 36611995 PMCID: PMC9818768 DOI: 10.3390/cells12010201] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/06/2022] [Revised: 12/22/2022] [Accepted: 12/30/2022] [Indexed: 01/06/2023] Open
Abstract
Therapy resistance is still a major reason for treatment failure in colorectal cancer (CRC). Previously, we identified the E3 ubiquitin ligase TRIM25 as a novel suppressor of caspase-2 translation which contributes to the apoptosis resistance of CRC cells towards chemotherapeutic drugs. Here, we report the executioner caspase-7 as being a further target of TRIM25. The results from the gain- and loss-of-function approaches and the actinomycin D experiments indicate that TRIM25 attenuates caspase-7 expression mainly through a decrease in mRNA stability. The data from the RNA pulldown assays with immunoprecipitated TRIM25 truncations indicate a direct TRIM25 binding to caspase-7 mRNA, which is mediated by the PRY/SPRY domain, which is also known to be highly relevant for protein-protein interactions. By employing TRIM25 immunoprecipitation, we identified the heterogeneous nuclear ribonucleoprotein H1 (hnRNPH1) as a novel TRIM25 binding protein with a functional impact on caspase-7 mRNA stability. Notably, the interaction of both proteins was highly sensitive to RNase A treatment and again depended on the PRY/SPRY domain, thus indicating an indirect interaction of both proteins which is achieved through a common RNA binding. Ubiquitin affinity chromatography showed that both proteins are targets of ubiquitin modification. Functionally, the ectopic expression of caspase-7 in CRC cells caused an increase in poly ADP-ribose polymerase (PARP) cleavage concomitant with a significant increase in apoptosis. Collectively, the negative regulation of caspase-7 by TRIM25, which is possibly executed by hnRNPH1, implies a novel survival mechanism underlying the chemotherapeutic drug resistance of CRC cells. The targeting of TRIM25 could therefore offer a promising strategy for the reduction in therapy resistance in CRC patients.
Collapse
|
2
|
Assoni G, La Pietra V, Digilio R, Ciani C, Licata NV, Micaelli M, Facen E, Tomaszewska W, Cerofolini L, Pérez-Ràfols A, Varela Rey M, Fragai M, Woodhoo A, Marinelli L, Arosio D, Bonomo I, Provenzani A, Seneci P. HuR-targeted agents: An insight into medicinal chemistry, biophysical, computational studies and pharmacological effects on cancer models. Adv Drug Deliv Rev 2022; 181:114088. [PMID: 34942276 DOI: 10.1016/j.addr.2021.114088] [Citation(s) in RCA: 10] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/06/2021] [Revised: 10/07/2021] [Accepted: 12/16/2021] [Indexed: 12/13/2022]
Abstract
The Human antigen R (HuR) protein is an RNA-binding protein, ubiquitously expressed in human tissues, that orchestrates target RNA maturation and processing both in the nucleus and in the cytoplasm. A survey of known modulators of the RNA-HuR interactions is followed by a description of its structure and molecular mechanism of action - RRM domains, interactions with RNA, dimerization, binding modes with naturally occurring and synthetic HuR inhibitors. Then, the review focuses on HuR as a validated molecular target in oncology and briefly describes its role in inflammation. Namely, we show ample evidence for the involvement of HuR in the hallmarks and enabling characteristics of cancer, reporting findings from in vitro and in vivo studies; and we provide abundant experimental proofs of a beneficial role for the inhibition of HuR-mRNA interactions through silencing (CRISPR, siRNA) or pharmacological inhibition (small molecule HuR inhibitors).
Collapse
Affiliation(s)
- Giulia Assoni
- Chemistry Department, University of Milan, Via Golgi 19, I-20133 Milan, Italy; Department of Cellular, Computational and Integrative Biology (CIBIO), University of Trento, via Sommarive 9, 38123 Trento, Italy
| | - Valeria La Pietra
- Department of Pharmacy, University of Napoli Federico II, Via D. Montesano 49, 80131 Napoli, Italy
| | - Rosangela Digilio
- Department of Cellular, Computational and Integrative Biology (CIBIO), University of Trento, via Sommarive 9, 38123 Trento, Italy
| | - Caterina Ciani
- Department of Cellular, Computational and Integrative Biology (CIBIO), University of Trento, via Sommarive 9, 38123 Trento, Italy
| | - Nausicaa Valentina Licata
- Department of Cellular, Computational and Integrative Biology (CIBIO), University of Trento, via Sommarive 9, 38123 Trento, Italy
| | - Mariachiara Micaelli
- Department of Cellular, Computational and Integrative Biology (CIBIO), University of Trento, via Sommarive 9, 38123 Trento, Italy
| | - Elisa Facen
- Department of Cellular, Computational and Integrative Biology (CIBIO), University of Trento, via Sommarive 9, 38123 Trento, Italy
| | - Weronika Tomaszewska
- Department of Cellular, Computational and Integrative Biology (CIBIO), University of Trento, via Sommarive 9, 38123 Trento, Italy
| | - Linda Cerofolini
- Magnetic Resonance Center (CERM), University of Florence and Interuniversity Consortium for Magnetic Resonance of Metalloproteins (CIRMMP), Via L. Sacconi 6, 50019 Sesto Fiorentino (FI), Italy
| | - Anna Pérez-Ràfols
- Giotto Biotech S.R.L., Via Madonna del Piano 6, 50019 Sesto Fiorentino (FI), Italy
| | - Marta Varela Rey
- Gene Regulatory Control in Disease Group, Center for Research in Molecular Medicine and Chronic Diseases (CIMUS), Health Research Institute of Santiago de Compostela (IDIS), University of Santiago de Compostela, 15706 Santiago de Compostela, Spain
| | - Marco Fragai
- Magnetic Resonance Center (CERM), University of Florence and Interuniversity Consortium for Magnetic Resonance of Metalloproteins (CIRMMP), Via L. Sacconi 6, 50019 Sesto Fiorentino (FI), Italy
| | - Ashwin Woodhoo
- Gene Regulatory Control in Disease Group, Center for Research in Molecular Medicine and Chronic Diseases (CIMUS), Health Research Institute of Santiago de Compostela (IDIS), University of Santiago de Compostela, 15706 Santiago de Compostela, Spain; Department of Functional Biology, University of Santiago de Compostela, 15782 Santiago de Compostela, Spain; Galician Agency of Innovation (GAIN), Xunta de Galicia, Santiago de Compostela, Spain; Center for Cooperative Research in Biosciences (CIC bioGUNE, Basque Research and Technology Alliance (BRTA), Bizkaia Technology Park, Building 801A, 48160 Derio, Spain; IKERBASQUE, Basque Foundation for Science, Bilbao 48013, Spain
| | - Luciana Marinelli
- Department of Pharmacy, University of Napoli Federico II, Via D. Montesano 49, 80131 Napoli, Italy
| | - Daniela Arosio
- Istituto di Scienze e Tecnologie Chimiche "G. Natta" (SCITEC), National Research Council (CNR), Via C. Golgi 19, I-20133 Milan, Italy
| | - Isabelle Bonomo
- Department of Cellular, Computational and Integrative Biology (CIBIO), University of Trento, via Sommarive 9, 38123 Trento, Italy
| | - Alessandro Provenzani
- Department of Cellular, Computational and Integrative Biology (CIBIO), University of Trento, via Sommarive 9, 38123 Trento, Italy.
| | - Pierfausto Seneci
- Chemistry Department, University of Milan, Via Golgi 19, I-20133 Milan, Italy.
| |
Collapse
|
3
|
Raguraman R, Shanmugarama S, Mehta M, Elle Peterson J, Zhao YD, Munshi A, Ramesh R. Drug delivery approaches for HuR-targeted therapy for lung cancer. Adv Drug Deliv Rev 2022; 180:114068. [PMID: 34822926 PMCID: PMC8724414 DOI: 10.1016/j.addr.2021.114068] [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: 10/17/2021] [Accepted: 11/18/2021] [Indexed: 01/03/2023]
Abstract
Lung cancer (LC) is often diagnosed at an advanced stage and conventional treatments for disease management have limitations associated with them. Novel therapeutic targets are thus avidly sought for the effective management of LC. RNA binding proteins (RBPs) have been convincingly established as key players in tumorigenesis, and their dysregulation is linked to multiple cancers, including LC. In this context, we review the role of Human antigen R (HuR), an RBP that is overexpressed in LC, and further associated with various aspects of LC tumor growth and response to therapy. Herein, we describe the role of HuR in LC progression and outline the evidences supporting various pharmacologic and biologic approaches for inhibiting HuR expression and function. These approaches, including use of small molecule inhibitors, siRNAs and shRNAs, have demonstrated favorable results in reducing tumor cell growth, invasion and migration, angiogenesis and metastasis. Hence, HuR has significant potential as a key therapeutic target in LC. Use of siRNA-based approaches, however, have certain limitations that prevent their maximal exploitation as cancer therapies. To address this, in the conclusion of this review, we provide a list of nanomedicine-based HuR targeting approaches currently being employed for siRNA and shRNA delivery, and provide a rationale for the immense potential therapeutic benefits offered by nanocarrier-based HuR targeting and its promise for treating patients with LC.
Collapse
Affiliation(s)
- Rajeswari Raguraman
- Department of Pathology, The University of Oklahoma Health Sciences Center, Oklahoma City, OK, USA; Stephenson Cancer Center, University of Oklahoma Health Sciences Center, Oklahoma City, OK, USA
| | - Santny Shanmugarama
- Department of Pathology, The University of Oklahoma Health Sciences Center, Oklahoma City, OK, USA; Graduate Program in Biomedical Sciences, University of Oklahoma Health Sciences Center, Oklahoma City, OK 73104, USA
| | - Meghna Mehta
- Radiation Oncology, The University of Oklahoma Health Sciences Center, Oklahoma City, OK, USA; Stephenson Cancer Center, University of Oklahoma Health Sciences Center, Oklahoma City, OK, USA
| | - Jo Elle Peterson
- Department of Pathology, The University of Oklahoma Health Sciences Center, Oklahoma City, OK, USA
| | - Yan D Zhao
- Biostatistics and Epidemiology, The University of Oklahoma Health Sciences Center, Oklahoma City, OK, USA; Stephenson Cancer Center, University of Oklahoma Health Sciences Center, Oklahoma City, OK, USA
| | - Anupama Munshi
- Radiation Oncology, The University of Oklahoma Health Sciences Center, Oklahoma City, OK, USA; Stephenson Cancer Center, University of Oklahoma Health Sciences Center, Oklahoma City, OK, USA
| | - Rajagopal Ramesh
- Department of Pathology, The University of Oklahoma Health Sciences Center, Oklahoma City, OK, USA; Stephenson Cancer Center, University of Oklahoma Health Sciences Center, Oklahoma City, OK, USA; Graduate Program in Biomedical Sciences, University of Oklahoma Health Sciences Center, Oklahoma City, OK 73104, USA.
| |
Collapse
|
4
|
Regulation of DNA Damage Response and Homologous Recombination Repair by microRNA in Human Cells Exposed to Ionizing Radiation. Cancers (Basel) 2020; 12:cancers12071838. [PMID: 32650508 PMCID: PMC7408912 DOI: 10.3390/cancers12071838] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/07/2020] [Revised: 06/26/2020] [Accepted: 06/29/2020] [Indexed: 12/12/2022] Open
Abstract
Ionizing radiation may be of both artificial and natural origin and causes cellular damage in living organisms. Radioactive isotopes have been used significantly in cancer therapy for many years. The formation of DNA double-strand breaks (DSBs) is the most dangerous effect of ionizing radiation on the cellular level. After irradiation, cells activate a DNA damage response, the molecular path that determines the fate of the cell. As an important element of this, homologous recombination repair is a crucial pathway for the error-free repair of DNA lesions. All components of DNA damage response are regulated by specific microRNAs. MicroRNAs are single-stranded short noncoding RNAs of 20–25 nt in length. They are directly involved in the regulation of gene expression by repressing translation or by cleaving target mRNA. In the present review, we analyze the biological mechanisms by which miRNAs regulate cell response to ionizing radiation-induced double-stranded breaks with an emphasis on DNA repair by homologous recombination, and its main component, the RAD51 recombinase. On the other hand, we discuss the ability of DNA damage response proteins to launch particular miRNA expression and modulate the course of this process. A full understanding of cell response processes to radiation-induced DNA damage will allow us to develop new and more effective methods of ionizing radiation therapy for cancers, and may help to develop methods for preventing the harmful effects of ionizing radiation on healthy organisms.
Collapse
|
5
|
Yang X, Sun X, Wu J, Ma J, Si P, Yin L, Zhang Y, Yan LJ, Zhang C. Regulation of the SIRT1 signaling pathway in NMDA-induced Excitotoxicity. Toxicol Lett 2020; 322:66-76. [PMID: 31945382 DOI: 10.1016/j.toxlet.2020.01.009] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/11/2019] [Revised: 10/12/2019] [Accepted: 01/12/2020] [Indexed: 12/20/2022]
Abstract
Silent Information Regulator 1 (SIRT1), an NAD+-dependent deacetylase, contributes to the neuroprotective effect. However, intracellular signaling pathways that affect SIRT1 function remain unknown. It is well known that N-methyl-D-aspartate (NMDA) receptor activation induces calcium influx which then activates PKC, and SIRT1 is a mRNA target for HuR protein. We hypothesize that Ca2+-PKC-HuR-SIRT1 pathway modulates SIRT1 function. The present study is to investigate the potential pathway of SIRT1 in the SH-SY5Y cell line as an in vitro model of NMDA-induced neurotoxicity. The results showed that: (1) SIRT1 levels were downregulated in NMDA model; (2) NMDA induced an increase in serine phosphorylation of HuR, while inhibition of serine phosphorylation of HuR increased SIRT1 levels, promoting cell survival; (3) PKC inhibitor (Gö 6976) reversed NMDA insults and also suppressed serine phosphorylation of HuR; (4) 1,2-bis(2-aminophenoxy)ethane-N,N,N',N'-tetraacetic acid (BAPTA-AM), an intracellular calcium chelator, fully reversed NMDA insults and also inhibited PKC activity evoked by NMDA. These results indicate that intracellular elevated Ca2+ activates PKC, which phosphorylates HuR and then promotes SIRT1 mRNA decay and subsequent neuronal death in NMDA model. Therefore, the study suggests that inhibition of Ca2+-PKC-HuR-SIRT1 pathway could be an effective strategy for preventing certain neurological diseases related to NMDA excitotoxicity.
Collapse
Affiliation(s)
- Xiaorong Yang
- Key Laboratory of Cellular Physiology (Shanxi Medical University), Ministry of Education, and the Department of Physiology, Shanxi Medical University, #56 Xin Jian South Road, Taiyuan 030001, Shanxi Province, PR China.
| | - Xuefei Sun
- Key Laboratory of Cellular Physiology (Shanxi Medical University), Ministry of Education, and the Department of Physiology, Shanxi Medical University, #56 Xin Jian South Road, Taiyuan 030001, Shanxi Province, PR China; The People's Hospital of Funing, Qinhuangdao 066300, Hebei Province, PR China
| | - Jinzi Wu
- Department of Pharmaceutical Sciences, UNT System College of Pharmacy, University of North Texas Health Science Center, Fort Worth, TX 76107, USA
| | - Jinteng Ma
- Key Laboratory of Cellular Physiology (Shanxi Medical University), Ministry of Education, and the Department of Physiology, Shanxi Medical University, #56 Xin Jian South Road, Taiyuan 030001, Shanxi Province, PR China
| | - Peipei Si
- Key Laboratory of Cellular Physiology (Shanxi Medical University), Ministry of Education, and the Department of Physiology, Shanxi Medical University, #56 Xin Jian South Road, Taiyuan 030001, Shanxi Province, PR China; Key Laboratory of Neurology of Hebei Province, The Second Hospital of Hebei Medical University, Shijiazhuang 050071, Hebei Province, PR China
| | - Litian Yin
- Key Laboratory of Cellular Physiology (Shanxi Medical University), Ministry of Education, and the Department of Physiology, Shanxi Medical University, #56 Xin Jian South Road, Taiyuan 030001, Shanxi Province, PR China
| | - Yu Zhang
- Key Laboratory of Cellular Physiology (Shanxi Medical University), Ministry of Education, and the Department of Physiology, Shanxi Medical University, #56 Xin Jian South Road, Taiyuan 030001, Shanxi Province, PR China
| | - Liang-Jun Yan
- Department of Pharmaceutical Sciences, UNT System College of Pharmacy, University of North Texas Health Science Center, Fort Worth, TX 76107, USA
| | - Ce Zhang
- Key Laboratory of Cellular Physiology (Shanxi Medical University), Ministry of Education, and the Department of Physiology, Shanxi Medical University, #56 Xin Jian South Road, Taiyuan 030001, Shanxi Province, PR China
| |
Collapse
|
6
|
Identification of TRIM25 as a Negative Regulator of Caspase-2 Expression Reveals a Novel Target for Sensitizing Colon Carcinoma Cells to Intrinsic Apoptosis. Cells 2019; 8:cells8121622. [PMID: 31842382 PMCID: PMC6952940 DOI: 10.3390/cells8121622] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/08/2019] [Revised: 12/04/2019] [Accepted: 12/10/2019] [Indexed: 12/14/2022] Open
Abstract
Colorectal cancer (CRC) is one of the most common cancers that is characterized by a high mortality due to the strong metastatic potential of the primary tumor and the high rate of therapy resistance. Hereby, evasion of apoptosis is the primary underlying cause of reduced sensitivity of tumor cells to chemo- and radiotherapy. Using RNA affinity chromatography, we identified the tripartite motif-containing protein 25 (TRIM25) as a bona fide caspase-2 mRNA-binding protein in colon carcinoma cells. Loss-of-function and gain-of-function approaches revealed that TRIM25 attenuates the protein levels of caspase-2 without significantly affecting caspase-2 mRNA levels. In addition, experiments with cycloheximide revealed that TRIM25 does not affect the protein stability of caspase-2. Furthermore, silencing of TRIM25 induced a significant redistribution of caspase-2 transcripts from RNP particles to translational active polysomes, indicating that TRIM25 negatively interferes with caspase-2 translation. Functionally, the elevation in caspase-2 upon TRIM25 depletion significantly increased the sensitivity of colorectal cells to drug-induced intrinsic apoptosis as implicated by increased caspase-3 cleavage and cytochrome c release. Importantly, the apoptosis-sensitizing effects by transient TRIM25 knockdown were rescued by concomitant silencing of caspase-2, demonstrating a critical role of caspase-2. Inhibition of caspase-2 by TRIM25 implies a survival mechanism that critically contributes to chemotherapeutic drug resistance in CRC.
Collapse
|
7
|
Pabis M, Popowicz GM, Stehle R, Fernández-Ramos D, Asami S, Warner L, García-Mauriño SM, Schlundt A, Martínez-Chantar ML, Díaz-Moreno I, Sattler M. HuR biological function involves RRM3-mediated dimerization and RNA binding by all three RRMs. Nucleic Acids Res 2019; 47:1011-1029. [PMID: 30418581 PMCID: PMC6344896 DOI: 10.1093/nar/gky1138] [Citation(s) in RCA: 53] [Impact Index Per Article: 10.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/01/2018] [Accepted: 10/28/2018] [Indexed: 12/22/2022] Open
Abstract
HuR/ELAVL1 is an RNA-binding protein involved in differentiation and stress response that acts primarily by stabilizing messenger RNA (mRNA) targets. HuR comprises three RNA recognition motifs (RRMs) where the structure and RNA binding of RRM3 and of full-length HuR remain poorly understood. Here, we report crystal structures of RRM3 free and bound to cognate RNAs. Our structural, NMR and biochemical data show that RRM3 mediates canonical RNA interactions and reveal molecular details of a dimerization interface localized on the α-helical face of RRM3. NMR and SAXS analyses indicate that the three RRMs in full-length HuR are flexibly connected in the absence of RNA, while they adopt a more compact arrangement when bound to RNA. Based on these data and crystal structures of tandem RRM1,2-RNA and our RRM3-RNA complexes, we present a structural model of RNA recognition involving all three RRM domains of full-length HuR. Mutational analysis demonstrates that RRM3 dimerization and RNA binding is required for functional activity of full-length HuR in vitro and to regulate target mRNAs levels in human cells, thus providing a fine-tuning for HuR activity in vivo.
Collapse
Affiliation(s)
- Marta Pabis
- Institute of Structural Biology, Helmholtz Zentrum München, Neuherberg, Germany.,Center for Integrated Protein Science Munich at Chair Biomolecular NMR Spectroscopy, Department Chemie, Technische Universität München, Lichtenbergstr. 4, 85747 Garching, Germany.,Max Planck Research Group hosted by the Malopolska Centre of Biotechnology of the Jagiellonian University, Krakow, Poland
| | - Grzegorz M Popowicz
- Institute of Structural Biology, Helmholtz Zentrum München, Neuherberg, Germany.,Center for Integrated Protein Science Munich at Chair Biomolecular NMR Spectroscopy, Department Chemie, Technische Universität München, Lichtenbergstr. 4, 85747 Garching, Germany
| | - Ralf Stehle
- Institute of Structural Biology, Helmholtz Zentrum München, Neuherberg, Germany.,Center for Integrated Protein Science Munich at Chair Biomolecular NMR Spectroscopy, Department Chemie, Technische Universität München, Lichtenbergstr. 4, 85747 Garching, Germany
| | - David Fernández-Ramos
- CIC bioGUNE, Centro de Investigación Cooperativa en Biociencias. Technology Park of Bizkaia, 48160 Derio, Bizkaia, Spain.,Centro de Investigación Biomédica en Red de Enfermedades Hepáticas y Digestivas (CIBERehd), Instituto de Salud Carlos III, Madrid, Spain
| | - Sam Asami
- Institute of Structural Biology, Helmholtz Zentrum München, Neuherberg, Germany.,Center for Integrated Protein Science Munich at Chair Biomolecular NMR Spectroscopy, Department Chemie, Technische Universität München, Lichtenbergstr. 4, 85747 Garching, Germany
| | - Lisa Warner
- Institute of Structural Biology, Helmholtz Zentrum München, Neuherberg, Germany.,Center for Integrated Protein Science Munich at Chair Biomolecular NMR Spectroscopy, Department Chemie, Technische Universität München, Lichtenbergstr. 4, 85747 Garching, Germany
| | - Sofía M García-Mauriño
- Instituto de Investigaciones Químicas (IIQ)-Centro de Investigaciones Científicas Isla de la Cartuja (cicCartuja), Universidad de Sevilla - Consejo Superior de Investigaciones Científicas (CSIC), Avda. Americo Vespucio 49, 41092 Sevilla, Spain
| | - Andreas Schlundt
- Institute of Structural Biology, Helmholtz Zentrum München, Neuherberg, Germany.,Center for Integrated Protein Science Munich at Chair Biomolecular NMR Spectroscopy, Department Chemie, Technische Universität München, Lichtenbergstr. 4, 85747 Garching, Germany
| | - María L Martínez-Chantar
- CIC bioGUNE, Centro de Investigación Cooperativa en Biociencias. Technology Park of Bizkaia, 48160 Derio, Bizkaia, Spain.,Centro de Investigación Biomédica en Red de Enfermedades Hepáticas y Digestivas (CIBERehd), Instituto de Salud Carlos III, Madrid, Spain
| | - Irene Díaz-Moreno
- Instituto de Investigaciones Químicas (IIQ)-Centro de Investigaciones Científicas Isla de la Cartuja (cicCartuja), Universidad de Sevilla - Consejo Superior de Investigaciones Científicas (CSIC), Avda. Americo Vespucio 49, 41092 Sevilla, Spain
| | - Michael Sattler
- Institute of Structural Biology, Helmholtz Zentrum München, Neuherberg, Germany.,Center for Integrated Protein Science Munich at Chair Biomolecular NMR Spectroscopy, Department Chemie, Technische Universität München, Lichtenbergstr. 4, 85747 Garching, Germany
| |
Collapse
|
8
|
Inhibition of Caspase-2 Translation by the mRNA Binding Protein HuR: A Novel Path of Therapy Resistance in Colon Carcinoma Cells? Cells 2019; 8:cells8080797. [PMID: 31366165 PMCID: PMC6721497 DOI: 10.3390/cells8080797] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/28/2019] [Revised: 07/26/2019] [Accepted: 07/29/2019] [Indexed: 12/28/2022] Open
Abstract
An increased expression and cytoplasmic abundance of the ubiquitous RNA binding protein human antigen R (HuR) is critically implicated in the dysregulated control of post- transcriptional gene expression during colorectal cancer development and is frequently associated with a high grade of malignancy and therapy resistance. Regardless of the fact that HuR elicits a broad cell survival program by increasing the stability of mRNAs coding for prominent anti-apoptotic factors, recent data suggest that HuR is critically involved in the regulation of translation, particularly, in the internal ribosome entry site (IRES) controlled translation of cell death regulatory proteins. Accordingly, data from human colon carcinoma cells revealed that HuR maintains constitutively reduced protein and activity levels of caspase-2 through negative interference with IRES-mediated translation. This review covers recent advances in the understanding of mechanisms underlying HuR's modulatory activity on IRES-triggered translation. With respect to the unique regulatory features of caspase-2 and its multiple roles (e.g., in DNA-damage-induced apoptosis, cell cycle regulation and maintenance of genomic stability), the pathophysiological consequences of negative caspase-2 regulation by HuR and its impact on therapy resistance of colorectal cancers will be discussed in detail. The negative HuR-caspase-2 axis may offer a novel target for tumor sensitizing therapies.
Collapse
|
9
|
Orr AA, Gonzalez-Rivera JC, Wilson M, Bhikha PR, Wang D, Contreras LM, Tamamis P. A high-throughput and rapid computational method for screening of RNA post-transcriptional modifications that can be recognized by target proteins. Methods 2018; 143:34-47. [DOI: 10.1016/j.ymeth.2018.01.015] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/16/2017] [Revised: 01/14/2018] [Accepted: 01/26/2018] [Indexed: 12/25/2022] Open
|
10
|
Badawi A, Biyanee A, Nasrullah U, Winslow S, Schmid T, Pfeilschifter J, Eberhardt W. Inhibition of IRES-dependent translation of caspase-2 by HuR confers chemotherapeutic drug resistance in colon carcinoma cells. Oncotarget 2018; 9:18367-18385. [PMID: 29719611 PMCID: PMC5915078 DOI: 10.18632/oncotarget.24840] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/08/2017] [Accepted: 02/23/2018] [Indexed: 12/31/2022] Open
Abstract
HuR plays an important role in tumor cell survival mainly through posttranscriptional upregulation of prominent anti-apoptotic genes. In addition, HuR can inhibit the translation of pro-apoptotic factors as we could previously report for caspase-2. Here, we investigated the mechanisms of caspase-2 suppression by HuR and its contribution to chemotherapeutic drug resistance of colon carcinoma cells. In accordance with the significant drug-induced increase in cytoplasmic HuR abundance, doxorubicin and paclitaxel increased the interaction of cytoplasmic HuR with the 5ʹuntranslated region (5ʹUTR) of caspase-2 as shown by RNA pull down assay. Experiments with bicistronic reporter genes furthermore indicate the presence of an internal ribosome entry site (IRES) within the caspase-2-5ʹUTR. Luciferase activity was suppressed either by chemotherapeutic drugs or ectopic expression of HuR. IRES-driven luciferase activity was significantly increased upon siRNA-mediated knockdown of HuR implicating an inhibitory effect of HuR on caspase-2 translation which is further reinforced by chemotherapeutic drugs. Comparison of RNA-binding affinities of recombinant HuR to two fragments of the caspase-2-5ʹUTR by EMSA revealed a critical HuR-binding site residing between nucleotides 111 and 241 of caspase-2-5ʹUTR. Mapping of critical RNA binding domains within HuR revealed that a fusion of RNA recognition motif 2 (RRM2) plus the hinge region confers a full caspase-2-5ʹUTR-binding. Functionally, knockdown of HuR significantly increased the sensitivity of colon cancer cells to drug-induced apoptosis. Importantly, the apoptosis sensitizing effects by HuR knockdown were rescued after silencing of caspase-2. The negative caspase-2 regulation by HuR offers a novel therapeutic target for sensitizing colon carcinoma cells to drug-induced apoptosis.
Collapse
Affiliation(s)
- Amel Badawi
- Pharmazentrum Frankfurt/ZAFES, Medical School, Goethe-University Frankfurt, Frankfurt/Main, Germany
| | - Abhiruchi Biyanee
- Pharmazentrum Frankfurt/ZAFES, Medical School, Goethe-University Frankfurt, Frankfurt/Main, Germany.,Present address: Institut für Biochemie, Westfälische Wilhelms-Universität Münster, Münster, Germany
| | - Usman Nasrullah
- Pharmazentrum Frankfurt/ZAFES, Medical School, Goethe-University Frankfurt, Frankfurt/Main, Germany
| | - Sofia Winslow
- Institute of Biochemistry I, Goethe-University Frankfurt, Frankfurt/Main, Germany
| | - Tobias Schmid
- Institute of Biochemistry I, Goethe-University Frankfurt, Frankfurt/Main, Germany
| | - Josef Pfeilschifter
- Pharmazentrum Frankfurt/ZAFES, Medical School, Goethe-University Frankfurt, Frankfurt/Main, Germany
| | - Wolfgang Eberhardt
- Pharmazentrum Frankfurt/ZAFES, Medical School, Goethe-University Frankfurt, Frankfurt/Main, Germany
| |
Collapse
|
11
|
Abstract
3'-untranslated regions (3'-UTRs) are the noncoding parts of mRNAs. Compared to yeast, in humans, median 3'-UTR length has expanded approximately tenfold alongside an increased generation of alternative 3'-UTR isoforms. In contrast, the number of coding genes, as well as coding region length, has remained similar. This suggests an important role for 3'-UTRs in the biology of higher organisms. 3'-UTRs are best known to regulate diverse fates of mRNAs, including degradation, translation, and localization, but they can also function like long noncoding or small RNAs, as has been shown for whole 3'-UTRs as well as for cleaved fragments. Furthermore, 3'-UTRs determine the fate of proteins through the regulation of protein-protein interactions. They facilitate cotranslational protein complex formation, which establishes a role for 3'-UTRs as evolved eukaryotic operons. Whereas bacterial operons promote the interaction of two subunits, 3'-UTRs enable the formation of protein complexes with diverse compositions. All of these 3'-UTR functions are accomplished by effector proteins that are recruited by RNA-binding proteins that bind to 3'-UTR cis-elements. In summary, 3'-UTRs seem to be major players in gene regulation that enable local functions, compartmentalization, and cooperativity, which makes them important tools for the regulation of phenotypic diversity of higher organisms.
Collapse
Affiliation(s)
- Christine Mayr
- Department of Cancer Biology and Genetics, Memorial Sloan Kettering Cancer Center, New York, NY 10065, USA;
| |
Collapse
|
12
|
Vlasova-St Louis I, Bohjanen PR. Post-transcriptional regulation of cytokine and growth factor signaling in cancer. Cytokine Growth Factor Rev 2016; 33:83-93. [PMID: 27956133 DOI: 10.1016/j.cytogfr.2016.11.004] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/14/2016] [Accepted: 11/28/2016] [Indexed: 12/11/2022]
Abstract
Cytokines and growth factors regulate cell proliferation, differentiation, migration and apoptosis, and play important roles in coordinating growth signal responses during development. The expression of cytokine genes and the signals transmitted through cytokine receptors are tightly regulated at several levels, including transcriptional and post-transcriptional levels. A majority of cytokine mRNAs, including growth factor transcripts, contain AU-rich elements (AREs) in their 3' untranslated regions that control gene expression by regulating mRNA degradation and changing translational rates. In addition, numerous proteins involved in transmitting signals downstream of cytokine receptors are regulated at the level of mRNA degradation by GU-rich elements (GREs) found in their 3' untranslated regions. Abnormal stabilization and overexpression of ARE or GRE-containing transcripts had been observed in many malignancies, which is a consequence of the malfunction of RNA-binding proteins. In this review, we briefly summarize the role of AREs and GREs in regulating mRNA turnover to coordinate cytokine and growth factor expression, and we describe how dysregulation of mRNA degradation mechanisms contributes to the development and progression of cancer.
Collapse
Affiliation(s)
| | - Paul R Bohjanen
- Department of Medicine, University of Minnesota, Minneapolis, MN, USA; Department of Microbiology and Immunology, University of Minnesota, Minneapolis, MN, USA
| |
Collapse
|
13
|
Marchese D, de Groot NS, Lorenzo Gotor N, Livi CM, Tartaglia GG. Advances in the characterization of RNA-binding proteins. WILEY INTERDISCIPLINARY REVIEWS. RNA 2016; 7:793-810. [PMID: 27503141 PMCID: PMC5113702 DOI: 10.1002/wrna.1378] [Citation(s) in RCA: 71] [Impact Index Per Article: 8.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 03/28/2016] [Revised: 06/14/2016] [Accepted: 06/23/2016] [Indexed: 12/14/2022]
Abstract
From transcription, to transport, storage, and translation, RNA depends on association with different RNA-binding proteins (RBPs). Methods based on next-generation sequencing and protein mass-spectrometry have started to unveil genome-wide interactions of RBPs but many aspects still remain out of sight. How many of the binding sites identified in high-throughput screenings are functional? A number of computational methods have been developed to analyze experimental data and to obtain insights into the specificity of protein-RNA interactions. How can theoretical models be exploited to identify RBPs? In addition to oligomeric complexes, protein and RNA molecules can associate into granular assemblies whose physical properties are still poorly understood. What protein features promote granule formation and what effects do these assemblies have on cell function? Here, we describe the newest in silico, in vitro, and in vivo advances in the field of protein-RNA interactions. We also present the challenges that experimental and computational approaches will have to face in future studies. WIREs RNA 2016, 7:793-810. doi: 10.1002/wrna.1378 For further resources related to this article, please visit the WIREs website.
Collapse
Affiliation(s)
- Domenica Marchese
- Centre for Genomic Regulation (CRG), The Barcelona Institute for Science and Technology, Dr. Aiguader 88, 08003 Barcelona, Spain
- Universitat Pompeu Fabra (UPF), Barcelona, Spain
| | - Natalia Sanchez de Groot
- Centre for Genomic Regulation (CRG), The Barcelona Institute for Science and Technology, Dr. Aiguader 88, 08003 Barcelona, Spain
- Universitat Pompeu Fabra (UPF), Barcelona, Spain
| | - Nieves Lorenzo Gotor
- Centre for Genomic Regulation (CRG), The Barcelona Institute for Science and Technology, Dr. Aiguader 88, 08003 Barcelona, Spain
- Universitat Pompeu Fabra (UPF), Barcelona, Spain
| | - Carmen Maria Livi
- Centre for Genomic Regulation (CRG), The Barcelona Institute for Science and Technology, Dr. Aiguader 88, 08003 Barcelona, Spain
- Universitat Pompeu Fabra (UPF), Barcelona, Spain
- IFOM Foundation, FIRC Institute of Molecular Oncology Foundation, Milan, Italy
| | - Gian G Tartaglia
- Centre for Genomic Regulation (CRG), The Barcelona Institute for Science and Technology, Dr. Aiguader 88, 08003 Barcelona, Spain.
- Universitat Pompeu Fabra (UPF), Barcelona, Spain.
- Institució Catalana de Recerca i Estudis Avançats (ICREA), Barcelona, Spain.
| |
Collapse
|
14
|
Kotta-Loizou I, Vasilopoulos SN, Coutts RHA, Theocharis S. Current Evidence and Future Perspectives on HuR and Breast Cancer Development, Prognosis, and Treatment. Neoplasia 2016; 18:674-688. [PMID: 27764700 PMCID: PMC5071540 DOI: 10.1016/j.neo.2016.09.002] [Citation(s) in RCA: 38] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/01/2016] [Revised: 09/14/2016] [Accepted: 09/19/2016] [Indexed: 12/20/2022] Open
Abstract
Hu-antigen R (HuR) is an RNA-binding posttranscriptional regulator that belongs to the Hu/ELAV family. HuR expression levels are modulated by a variety of proteins, microRNAs, chemical compounds, or the microenvironment, and in turn, HuR affects mRNA stability and translation of various genes implicated in breast cancer formation, progression, metastasis, and treatment. The aim of the present review is to critically summarize the role of HuR in breast cancer development and its potential as a prognosticator and a therapeutic target. In this aspect, all the existing English literature concerning HuR expression and function in breast cancer cell lines, in vivo animal models, and clinical studies is critically presented and summarized. HuR modulates many genes implicated in biological processes crucial for breast cancer formation, growth, and metastasis, whereas the link between HuR and these processes has been demonstrated directly in vitro and in vivo. Additionally, clinical studies reveal that HuR is associated with more aggressive forms of breast cancer and is a putative prognosticator for patients' survival. All the above indicate HuR as a promising drug target for cancer therapy; nevertheless, additional studies are required to fully understand its potential and determine against which types of breast cancer and at which stage of the disease a therapeutic agent targeting HuR would be more effective.
Collapse
Affiliation(s)
- Ioly Kotta-Loizou
- Department of Life Sciences, Faculty of Natural Sciences, Imperial College London, London SW7 2AZ, United Kingdom; First Department of Pathology, Medical School, National and Kapodistrian University of Athens, Athens 11527, Greece.
| | - Spyridon N Vasilopoulos
- First Department of Pathology, Medical School, National and Kapodistrian University of Athens, Athens 11527, Greece
| | - Robert H A Coutts
- Geography, Environment and Agriculture Division, Department of Biological and Environmental Sciences, School of Life and Medical Sciences, University of Hertfordshire, Hatfield AL10 9AB, United Kingdom
| | - Stamatios Theocharis
- First Department of Pathology, Medical School, National and Kapodistrian University of Athens, Athens 11527, Greece
| |
Collapse
|
15
|
Sommese RF, Sivaramakrishnan S. Substrate Affinity Differentially Influences Protein Kinase C Regulation and Inhibitor Potency. J Biol Chem 2016; 291:21963-21970. [PMID: 27555323 DOI: 10.1074/jbc.m116.737601] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/10/2016] [Indexed: 02/05/2023] Open
Abstract
The overlapping network of kinase-substrate interactions provides exquisite specificity in cell signaling pathways, but also presents challenges to our ability to understand the mechanistic basis of biological processes. Efforts to dissect kinase-substrate interactions have been particularly limited by their inherently transient nature. Here, we use a library of FRET sensors to monitor these transient complexes, specifically examining weak interactions between the catalytic domain of protein kinase Cα and 14 substrate peptides. Combining results from this assay platform with those from standard kinase activity assays yields four novel insights into the kinase-substrate interaction. First, preferential binding of non-phosphorylated versus phosphorylated substrates leads to enhanced kinase-specific activity. Second, kinase-specific activity is inversely correlated with substrate binding affinity. Third, high affinity substrates can suppress phosphorylation of their low affinity counterparts. Finally, the substrate-competitive inhibitor bisindolylmaleimide I displaces low affinity substrates more potently leading to substrate selective inhibition of kinase activity. Overall, our approach complements existing structural and biophysical approaches to provide generalizable insights into the regulation of kinase activity.
Collapse
Affiliation(s)
- Ruth F Sommese
- From the Department of Genetics, Cell Biology, and Development, University of Minnesota, Minneapolis, Minnesota 55455
| | - Sivaraj Sivaramakrishnan
- From the Department of Genetics, Cell Biology, and Development, University of Minnesota, Minneapolis, Minnesota 55455
| |
Collapse
|
16
|
Eberhardt W, Badawi A, Biyanee A, Pfeilschifter J. Cytoskeleton-Dependent Transport as a Potential Target for Interfering with Post-transcriptional HuR mRNA Regulons. Front Pharmacol 2016; 7:251. [PMID: 27582706 PMCID: PMC4987335 DOI: 10.3389/fphar.2016.00251] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/27/2016] [Accepted: 08/02/2016] [Indexed: 01/04/2023] Open
Abstract
The ubiquitous mRNA binding protein human antigen R (HuR), a member of the embryonal lethal abnormal vision protein family has a critical impact on the post-transcriptional control of AU-rich element bearing mRNA regulons implied in inflammation, senescence, and carcinogenesis. HuR in addition to mRNA stability can affect many other aspects of mRNA processing including splicing, polyadenylation, translation, modulation of miRNA repression, and intracellular mRNA trafficking. Since many of the identified HuR mRNA targets ("HuR mRNA regulons") encode tumor-related proteins, HuR is not only discussed as an useful biomarker but also as promising therapeutic target for treatment of various human cancers. HuR which is most abundantly localized in the nucleus is translocated to the cytoplasm which is fundamental for most of the described HuR functions on target mRNAs. Accordingly, an elevation in cytoplasmic HuR was found in many tumors and correlated with a high grade of malignancy and a poor prognosis of patients. Therefore, direct interference with the intracellular trafficking of HuR offers an attractive approach to intervene with pathologically deregulated HuR functions. Data from several laboratories implicate that the integrity of the cytoskeleton is critical for HuR-mediated intracellular mRNA localization and translation. This review will particularly focus on drugs which have proven a direct inhibitory effect on HuR translocation. Based on the results from those studies, we will also discuss on the principle value of targeting cytoskeleton-dependent transport of HuR by natural or synthetic inhibitors as a potential therapeutic avenue for interfering with dysregulated post-transcriptional HuR mRNA regulons and related tumor cell functions. In spite of that, interfering with cytoplasmic HuR transport could highlight a so far underestimated action of microtubule inhibitors clinically used for cancer chemotherapy.
Collapse
Affiliation(s)
- Wolfgang Eberhardt
- Pharmazentrum Frankfurt/ZAFES, Klinikum der Johann Wolfgang Goethe-Universität Frankfurt am Main, Germany
| | - Amel Badawi
- Pharmazentrum Frankfurt/ZAFES, Klinikum der Johann Wolfgang Goethe-Universität Frankfurt am Main, Germany
| | - Abhiruchi Biyanee
- Pharmazentrum Frankfurt/ZAFES, Klinikum der Johann Wolfgang Goethe-Universität Frankfurt am Main, Germany
| | - Josef Pfeilschifter
- Pharmazentrum Frankfurt/ZAFES, Klinikum der Johann Wolfgang Goethe-Universität Frankfurt am Main, Germany
| |
Collapse
|
17
|
Slone S, Anthony SR, Wu X, Benoit JB, Aube J, Xu L, Tranter M. Activation of HuR downstream of p38 MAPK promotes cardiomyocyte hypertrophy. Cell Signal 2016; 28:1735-41. [PMID: 27521603 DOI: 10.1016/j.cellsig.2016.08.005] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/01/2016] [Revised: 08/02/2016] [Accepted: 08/08/2016] [Indexed: 10/21/2022]
Abstract
The RNA binding protein Human antigen R (HuR) interacts with specific AU-rich domains in target mRNAs and is highly expressed in many cell types, including cardiomyocytes. However, the role of HuR in cardiac physiology is largely unknown. Our results show that HuR undergoes cytoplasmic translocation, indicative of its activation, in hypertrophic cardiac myocytes. Specifically, HuR cytoplasmic translocation is significantly increased in NRVMs (neonatal rat ventricular myocytes) following treatment with phenylephrine or angiotensin II, agonists of two independent Gαq-coupled GPCRs known to induce hypertrophy. This Gq-mediated HuR activation is dependent on p38 MAP kinase, but not canonical Gq-PKC signaling. Furthermore, we show that HuR activation is necessary for Gq-mediated hypertrophic growth of NRVMs as siRNA-mediated knockdown of HuR inhibits hypertrophy as measured by cell size and expression of ANF (atrial natriuretic factor). Additionally, HuR overexpression is sufficient to induce hypertrophic cell growth. To decipher the downstream mechanisms by which HuR translocation promotes cardiomyocyte hypertrophy, we assessed the role of HuR in the transcriptional activity of NFAT (nuclear factor of activated T cells), the activation of which is a hallmark of cardiac hypertrophy. Using an NFAT-luciferase reporter assay, we show an acute inhibition of NFAT transcriptional activity following pharmacological inhibition of HuR. In conclusion, our results identify HuR as a novel mediator of cardiac hypertrophy downstream of the Gq-p38 MAPK pathway, and suggest modulation of NFAT activity as a potential mechanism.
Collapse
Affiliation(s)
- Samuel Slone
- Division of Cardiovascular Health and Disease, University of Cincinnati College of Medicine, Cincinnati, OH, United States
| | - Sarah R Anthony
- Division of Cardiovascular Health and Disease, University of Cincinnati College of Medicine, Cincinnati, OH, United States
| | - Xiaoqing Wu
- Department of Molecular Biosciences, University of Kansas, Lawrence, KS, United States
| | - Joshua B Benoit
- Department of Biological Sciences, McMicken College of Arts and Sciences, University of Cincinnati, Cincinnati, OH, United States
| | - Jeffrey Aube
- Department of Medicinal Chemistry, Eshelman School of Pharmacy, University of North Carolina, Chapel Hill, NC, United States
| | - Liang Xu
- Department of Molecular Biosciences, University of Kansas, Lawrence, KS, United States
| | - Michael Tranter
- Division of Cardiovascular Health and Disease, University of Cincinnati College of Medicine, Cincinnati, OH, United States.
| |
Collapse
|
18
|
Essential Roles of RNA-binding Protein HuR in Activation of Hepatic Stellate Cells Induced by Transforming Growth Factor-β1. Sci Rep 2016; 6:22141. [PMID: 26912347 PMCID: PMC4766441 DOI: 10.1038/srep22141] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/18/2015] [Accepted: 02/08/2016] [Indexed: 11/08/2022] Open
Abstract
RNA-binding protein HuR mediates transforming growth factor (TGF)-β1-induced profibrogenic actions. Up-regulation of Sphingosine kinase 1 (SphK1) is involved in TGF-β1-induced activation of hepatic stellate cells (HSCs) in liver fibrogenesis. However, the molecular mechanism of TGF-β1 regulates SphK1 remains unclear. This study was designed to investigate the role of HuR in TGF-β1-induced SphK1 expression and identify a new molecular mechanism in liver fibrogenensis. In vivo, HuR expression was increased, translocated to cytoplasm, and bound to SphK1 mRNA in carbon tetrachloride- and bile duct ligation-induced mouse fibrotic liver. HuR mRNA expression had a positive correlation with mRNA expressions of SphK1 and fibrotic markers, α-smooth muscle actin (α-SMA) and Collagen α1(I), respectively. In vitro, up-regulation of SphK1 and activation of HSCs stimulated by TGF-β1 depended on HuR cytoplasmic accumulation. The effects of TGF-β1 were diminished when HuR was silenced or HuR cytoplasmic translocation was blocked. Meanwhile, overexpression of HuR mimicked the effects of TGF-β1. Furthermore, TGF-β1 prolonged half-life of SphK1 mRNA by promoting its binding to HuR. Pharmacological or siRNA-induced SphK1 inhibition abrogated HuR-mediated HSC activation. In conclusion, our data suggested that HuR bound to SphK1 mRNA and played a crucial role in TGF-β1-induced HSC activation.
Collapse
|
19
|
Scheiba RM, de Opakua AI, Díaz-Quintana A, Cruz-Gallardo I, Martínez-Cruz LA, Martínez-Chantar ML, Blanco FJ, Díaz-Moreno I. The C-terminal RNA binding motif of HuR is a multi-functional domain leading to HuR oligomerization and binding to U-rich RNA targets. RNA Biol 2015; 11:1250-61. [PMID: 25584704 DOI: 10.1080/15476286.2014.996069] [Citation(s) in RCA: 49] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022] Open
Abstract
Human antigen R (HuR) is a 32 kDa protein with 3 RNA Recognition Motifs (RRMs), which bind to Adenylate and uridylate Rich Elements (AREs) of mRNAs. Whereas the N-terminal and central domains (RRM1 and RRM2) are essential for AREs recognition, little is known on the C-terminal RRM3 beyond its implication in HuR oligomerization and apoptotic signaling. We have developed a detergent-based strategy to produce soluble RRM3 for structural studies. We have found that it adopts the typical RRM fold, does not interact with the RRM1 and RRM2 modules, and forms dimers in solution. Our NMR measurements, combined with Molecular Dynamics simulations and Analytical Ultracentrifugation experiments, show that the protein dimerizes through a helical region that contains the conserved W261 residue. We found that HuR RRM3 binds to 5'-mer U-rich RNA stretches through the solvent exposed side of its β-sheet, located opposite to the dimerization site. Upon mimicking phosphorylation by the S318D replacement, RRM3 mutant shows less ability to recognize RNA due to an electrostatic repulsion effect with the phosphate groups. Our study brings new insights of HuR RRM3 as a domain involved in protein oligomerization and RNA interaction, both functions regulated by 2 surfaces on opposite sides of the RRM domain.
Collapse
Key Words
- AREs, Adenylate and uridylate Rich Elements
- AU, Analytical Ultracentrifugation
- CARM1, Coactivator associated Arginine Methyltransferase 1
- CD, Circular Dichroism
- Cdk1, Cyclin-dependent kinase 1
- Chk2, Checkpoint kinase 2
- ELAV1, Embryonic Lethal Abnormal Vision system human homolog 1
- EMSA, Electrophoretic Mobility Shift Assay
- FIR, FBP-Interacting Repressor
- FL, Full-Length, HNS, HuR Nucleocytoplasmic Shuttling Sequence
- HSQC, Heteronuclear Single-Quantum Correlation
- HuR, Human antigen R
- Human antigen R (HuR)
- MD, Molecular Dynamics
- NMR, Nuclear Magnetic Resonance
- NOE, Nuclear Overhauser Effect
- Nuclear Magnetic Resonance (NMR)
- PCA, Principal Component Analysis
- PKCα, Protein Kinase C α
- PKCδ, Protein Kinase C δ
- PMSF, PhenylMethylSulfonyl Fluoride
- PTB, Polypyrimidine Tract Binding protein
- RBPs, RNA Binding Proteins
- RNA binding
- RNA binding protein (RBP)
- RNA recognition motif (RRM)
- RRMs, RNA Recognition Motifs
- SPR, Surface Plasmon Resonance
- Serine Phosphorylation
- WT, Wild-Type
- dimerization
- hnRNP1, heterogeneous nuclear RiboNucleoprotein C protein
Collapse
Affiliation(s)
- Rafael M Scheiba
- a Instituto de Bioquímica Vegetal y Fotosíntesis; cicCartuja ; Sevilla , Spain
| | | | | | | | | | | | | | | |
Collapse
|
20
|
Lymphotoxin α, a novel target of posttranscriptional gene regulation by HuR in HepG2 cells. FEBS Lett 2015; 589:1943-50. [PMID: 25980610 DOI: 10.1016/j.febslet.2015.05.015] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/03/2015] [Revised: 04/24/2015] [Accepted: 05/06/2015] [Indexed: 12/31/2022]
Abstract
The role of the RNA-binding protein human antigen R (HuR) in hepatocarcinogenesis is still elusive. By employing short hairpin (sh)RNA-dependent knockdown approach, we demonstrate that lymphotoxin α (LTα) is a target of posttranscriptional gene regulation by HuR in hepatocellular carcinoma (HepG2) cells. Consequently, the increased mRNA decay upon HuR depletion significantly affects lymphotoxin expression at both, the mRNA and protein level. Biotin-pulldown assay showed that HuR specifically interacts with the 3'-untranslated region (3'-UTR) of the LTα mRNA. Furthermore, electrophoretic mobility shift assay (EMSA) implicates that the RNA-binding critically depends on the RNA recognition motif 2 (RRM2) and the hinge region of HuR.
Collapse
|
21
|
Shen ZJ, Malter JS. Regulation of AU-Rich Element RNA Binding Proteins by Phosphorylation and the Prolyl Isomerase Pin1. Biomolecules 2015; 5:412-34. [PMID: 25874604 PMCID: PMC4496679 DOI: 10.3390/biom5020412] [Citation(s) in RCA: 29] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/04/2015] [Revised: 03/23/2015] [Accepted: 03/31/2015] [Indexed: 01/19/2023] Open
Abstract
The accumulation of 3' untranslated region (3'-UTR), AU-rich element (ARE) containing mRNAs, are predominantly controlled at the post-transcriptional level. Regulation appears to rely on a variable and dynamic interaction between mRNA target and ARE-specific binding proteins (AUBPs). The AUBP-ARE mRNA recognition is directed by multiple intracellular signals that are predominantly targeted at the AUBPs. These include (but are unlikely limited to) methylation, acetylation, phosphorylation, ubiquitination and isomerization. These regulatory events ultimately affect ARE mRNA location, abundance, translation and stability. In this review, we describe recent advances in our understanding of phosphorylation and its impact on conformation of the AUBPs, interaction with ARE mRNAs and highlight the role of Pin1 mediated prolyl cis-trans isomerization in these biological process.
Collapse
Affiliation(s)
- Zhong-Jian Shen
- Department of Pathology, University of Texas Southwestern Medical Center, Dallas, TX 75390-8548, USA.
| | - James S Malter
- Department of Pathology, University of Texas Southwestern Medical Center, Dallas, TX 75390-8548, USA.
| |
Collapse
|
22
|
Abstract
ELAV (embryonic lethal/abnormal visual system)/Hu proteins comprise a family of highly related neuronal RBPs (RNA-binding proteins) involved in many aspects of mRNA processing. Although they bind to highly similar short sequence motifs, they have acquired diverse functions suggesting that cellular signalling is important for their functional diversification. Indeed, ELAV/Hu proteins harbour many phosphorylatable amino acids. In the present article, we review our current knowledge about phosphorylation of ELAV/Hu proteins and how phosphorylation affects cellular localization of ELAV/Hu proteins and their binding to RNA.
Collapse
|
23
|
CNOT7/hCAF1 is involved in ICAM-1 and IL-8 regulation by tristetraprolin. Cell Signal 2014; 26:2390-6. [PMID: 25038453 DOI: 10.1016/j.cellsig.2014.07.020] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/25/2014] [Accepted: 07/10/2014] [Indexed: 11/22/2022]
Abstract
Tristetraprolin (TTP) is an RNA-binding protein which can bind to the AU-rich elements (AREs) at the 3'-untranslated region (3'-UTR) of target mRNA and promote mRNA deadenylation and degradation. We have shown in a previous study that TTP regulates tumor necrosis factor-α (TNF-α)-induced expression of intercellular adhesion molecule-1 (ICAM-1) and interleukin-8 (IL-8), both of whose mRNAs have AREs in the 3'-UTR, in human pulmonary microvascular endothelial cells (HPMEC) through destabilizing target mRNAs, nevertheless, the mechanism by which TTP promotes mRNA decay remains unclear. Observations have indicated that TTP can interact with CAF1 (CNOT7/hCAF1 in human), a subunit of the CCR4-NOT complex with deadenylase activity. Another study illustrated that TTP can directly bind to CNOT1, the scaffold subunit of the CCR4-NOT complex. The present study showed that TTP bound to the AREs of ICAM-1 and IL-8 mRNAs and was coimmunoprecipitated with intracellular ICAM-1 and IL-8 mRNAs. TTP, CNOT7 and CNOT1 were coimmunoprecipitated in HPMEC. CNOT7 silencing stabilized ICAM-1 and IL-8 mRNAs and increased ICAM-1 and IL-8 production following TNF-α stimulation. These results, together with our previous study, suggest that CNOT7/hCAF1 is involved in ICAM-1 and IL-8 regulation by TTP in HPMEC.
Collapse
|
24
|
Latorre E, Castiglioni I, Gatto P, Carelli S, Quattrone A, Provenzani A. Loss of protein kinase Cδ/HuR interaction is necessary to doxorubicin resistance in breast cancer cell lines. J Pharmacol Exp Ther 2014; 349:99-106. [PMID: 24492650 DOI: 10.1124/jpet.113.211839] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
The protein kinase Cδ (PKCδ) interacts with and phosphorylates HuR, dictating its functionality. We show here that the genotoxic stimulus induced by doxorubicin triggers PKCδ interaction with HuR and leads to HuR phosphorylation on serines 221 and 318 and cytoplasmic translocation. This series of events is crucial to elicit the death pathway triggered by doxorubicin and is necessary to promote HuR function in post-transcriptional regulation of gene expression, because genetic ablation of PKCδ caused the inability of HuR to bind its target mRNAs, topoisomerase IIα (TOP2A) included. In in vitro select doxorubicin-resistant human breast cancer cell lines upregulating the multidrug resistance marker ABCG2, PKCδ, and HuR proteins were coordinately downregulated together with the doxorubicin target TOP2A protein whose mRNA was HuR-regulated. Therefore, we show here that PKCδ, HuR, and TOP2A constitute a network mediating doxorubicin efficacy in breast cancer cells. The importance of these molecular events in cancer therapy is suggested by their being profoundly suppressed in cells selected for doxorubicin resistance.
Collapse
Affiliation(s)
- Elisa Latorre
- Laboratory of Genomic Screening (E.L., I.C., A.P.) and Laboratory of Translational Genomics (P.G., A.Q.), Centre for Integrative Biology, University of Trento, Italy; and Pharmacology Laboratory, Health Sciences Department, University of Milan, Italy (E.L., S.C.)
| | | | | | | | | | | |
Collapse
|