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Khan FA, Fang N, Zhang W, Ji S. The multifaceted role of Fragile X-Related Protein 1 (FXR1) in cellular processes: an updated review on cancer and clinical applications. Cell Death Dis 2024; 15:72. [PMID: 38238286 PMCID: PMC10796922 DOI: 10.1038/s41419-023-06413-8] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/14/2023] [Revised: 12/20/2023] [Accepted: 12/21/2023] [Indexed: 01/22/2024]
Abstract
RNA-binding proteins (RBPs) modulate the expression level of several target RNAs (such as mRNAs) post-transcriptionally through interactions with unique binding sites in the 3'-untranslated region. There is mounting information that suggests RBP dysregulation plays a significant role in carcinogenesis. However, the function of FMR1 autosomal homolog 1(FXR1) in malignancies is just beginning to be unveiled. Due to the diversity of their RNA-binding domains and functional adaptability, FXR1 can regulate diverse transcript processing. Changes in FXR1 interaction with RNA networks have been linked to the emergence of cancer, although the theoretical framework defining these alterations in interaction is insufficient. Alteration in FXR1 expression or localization has been linked to the mRNAs of cancer suppressor genes, cancer-causing genes, and genes involved in genomic expression stability. In particular, FXR1-mediated gene regulation involves in several cellular phenomena related to cancer growth, metastasis, epithelial-mesenchymal transition, senescence, apoptosis, and angiogenesis. FXR1 dysregulation has been implicated in diverse cancer types, suggesting its diagnostic and therapeutic potential. However, the molecular mechanisms and biological effects of FXR1 regulation in cancer have yet to be understood. This review highlights the current knowledge of FXR1 expression and function in various cancer situations, emphasizing its functional variety and complexity. We further address the challenges and opportunities of targeting FXR1 for cancer diagnosis and treatment and propose future directions for FXR1 research in oncology. This work intends to provide an in-depth review of FXR1 as an emerging oncotarget with multiple roles and implications in cancer biology and therapy.
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Affiliation(s)
- Faiz Ali Khan
- Huaihe Hospital,Medical School, Henan University, Kaifeng, China
- Laboratory of Cell Signal Transduction, Department of Biochemistry and Molecular Biology, School of Basic Medical Sciences, Henan University, Kaifeng, China
- Department of Basic Sciences Research, Shaukat Khanum Memorial Cancer Hospital and Research Centre (SKMCH&RC), Lahore, Pakistan
| | - Na Fang
- Huaihe Hospital,Medical School, Henan University, Kaifeng, China.
- Laboratory of Cell Signal Transduction, Department of Biochemistry and Molecular Biology, School of Basic Medical Sciences, Henan University, Kaifeng, China.
| | - Weijuan Zhang
- Huaihe Hospital,Medical School, Henan University, Kaifeng, China.
- Laboratory of Cell Signal Transduction, Department of Biochemistry and Molecular Biology, School of Basic Medical Sciences, Henan University, Kaifeng, China.
| | - Shaoping Ji
- Huaihe Hospital,Medical School, Henan University, Kaifeng, China.
- Laboratory of Cell Signal Transduction, Department of Biochemistry and Molecular Biology, School of Basic Medical Sciences, Henan University, Kaifeng, China.
- Zhengzhou Shuqing Medical College, Zhengzhou, China.
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2
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Wang SR, Mallard CG, Cairns CA, Chung HK, Yoo D, Jaladanki SK, Xiao L, Wang JY. Stabilization of Cx43 mRNA via RNA-binding protein HuR regulated by polyamines enhances intestinal epithelial barrier function. Am J Physiol Gastrointest Liver Physiol 2023; 325:G518-G527. [PMID: 37788332 PMCID: PMC10894663 DOI: 10.1152/ajpgi.00143.2023] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/11/2023] [Revised: 08/22/2023] [Accepted: 09/29/2023] [Indexed: 10/05/2023]
Abstract
Gut barrier dysfunction occurs commonly in patients with critical disorders, leading to the translocation of luminal toxic substances and bacteria to the bloodstream. Connexin 43 (Cx43) acts as a gap junction protein and is crucial for intercellular communication and the diffusion of nutrients. The levels of cellular Cx43 are tightly regulated by multiple factors, including polyamines, but the exact mechanism underlying the control of Cx43 expression remains largely unknown. The RNA-binding protein HuR regulates the stability and translation of target mRNAs and is involved in many aspects of intestinal epithelial pathobiology. Here we show that HuR directly bound to Cx43 mRNA via its 3'-untranslated region in intestinal epithelial cells (IECs) and this interaction enhanced Cx43 expression by stabilizing Cx43 mRNA. Depletion of cellular polyamines inhibited the [HuR/Cx43 mRNA] complex and decreased the level of Cx43 protein by destabilizing its mRNA, but these changes were prevented by ectopic overexpression of HuR. Polyamine depletion caused intestinal epithelial barrier dysfunction, which was reversed by ectopic Cx43 overexpression. Moreover, overexpression of checkpoint kinase 2 in polyamine-deficient cells increased the [HuR/Cx43 mRNA] complex, elevated Cx43 levels, and promoted barrier function. These findings indicate that Cx43 mRNA is a novel target of HuR in IECs and that polyamines regulate Cx43 mRNA stability via HuR, thus playing a critical role in the maintenance of intestinal epithelial barrier function.NEW & NOTEWORTHY The current study shows that polyamines stabilize the Cx43 mRNA via HuR, thus enhancing the function of the Cx43-mediated gap junction. These findings suggest that induced Cx43 by HuR plays a critical role in the process by which polyamines regulate intestinal epithelial barrier.
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Affiliation(s)
- Shelley R Wang
- Cell Biology Group, Department of Surgery, University of Maryland School of Medicine, Baltimore, Maryland, United States
| | - Caroline G Mallard
- Cell Biology Group, Department of Surgery, University of Maryland School of Medicine, Baltimore, Maryland, United States
| | - Cassandra A Cairns
- Cell Biology Group, Department of Surgery, University of Maryland School of Medicine, Baltimore, Maryland, United States
| | - Hee Kyoung Chung
- Cell Biology Group, Department of Surgery, University of Maryland School of Medicine, Baltimore, Maryland, United States
| | - Dongyoon Yoo
- Cell Biology Group, Department of Surgery, University of Maryland School of Medicine, Baltimore, Maryland, United States
| | - Suraj K Jaladanki
- Cell Biology Group, Department of Surgery, University of Maryland School of Medicine, Baltimore, Maryland, United States
| | - Lan Xiao
- Cell Biology Group, Department of Surgery, University of Maryland School of Medicine, Baltimore, Maryland, United States
| | - Jian-Ying Wang
- Cell Biology Group, Department of Surgery, University of Maryland School of Medicine, Baltimore, Maryland, United States
- Department of Pathology, University of Maryland School of Medicine, Baltimore, Maryland, United States
- Baltimore Veterans Affairs Medical Center, Baltimore, Maryland, United States
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3
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Zhang M, Cao L, Hou G, Lv X, Deng J. Investigation of the Potential Correlation Between RNA-Binding Proteins in the Evolutionarily Conserved MEX3 Family and Non-small-Cell Lung Cancer. Mol Biotechnol 2022:10.1007/s12033-022-00638-2. [DOI: 10.1007/s12033-022-00638-2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/27/2022] [Accepted: 12/05/2022] [Indexed: 12/14/2022]
Abstract
Abstract
Members of the MEX3 (muscle excess 3) family, uniquely characterised as mRNA binding proteins, play emerging roles in the post-transcriptional regulation of programmed biological processes, including tumour cell death and immune mechanisms, and have been shown to be involved in a variety of diseases. However, the role of MEX3 in non-small cell lung cancer (NSCLC) has not been fully elucidated. In this study, we found no significant changes in the sequence and copy number of the MEX3 gene through analysis using the COSMIC database, revealing its stability during malignancy development. Its expression in NSCLC was examined using the Oncomine™ database, and the prognosis of each member gene was analysed by Kaplan–Meier. The results showed that overexpression of MEX3A, MEX3B, MEX3C and MEX3D was associated with significantly worse OS in patients with LUAD, while overexpression of MEX3D was also associated with significantly worse OS in patients with LUSC. Afterwards, we applied the Tumour Immunology Estimation Resource (TIMER) tool to assess the correlation between different MEX3 and infiltrative immune cell infiltration. Ultimately, we found that most MEX3 members were highly expressed in NSCLC, with high expression suggesting poor prognosis and correlating with immune cell infiltration. The complexity and heterogeneity of NSCLC was understood through MEX3, setting the framework for the prognostic impact of MEX3 in NSCLC patients and the development of new targeted therapeutic strategies in the future.
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The RNA-binding protein HuR regulates intestinal epithelial restitution by modulating Caveolin-1 gene expression. Biochem J 2021; 478:247-260. [PMID: 33346337 DOI: 10.1042/bcj20200372] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/19/2020] [Revised: 11/24/2020] [Accepted: 12/21/2020] [Indexed: 12/12/2022]
Abstract
The integrity of the intestinal mucosal barrier protects hosts against pathological conditions. Early mucosal restitution after wounding refers to epithelial cell migration into a defect. The RNA-binding protein HuR plays an important role in the posttranscriptional regulation of gene expression and is involved in many aspects of cellular physiology. In the present study, we investigated the role of HuR in the regulation of cell migration through the posttranscriptional regulation of Caveolin-1 (Cav-1). Online software was used to identify Cav-1 mRNA as a potential target of HuR. The interaction of HuR with Cav-1 mRNA was investigated via ribonucleoprotein immunoprecipitation (RNP IP) assays and biotin pulldown analysis. HuR was found to bind specifically to the Cav-1 3'-UTR rather than the coding region or 5'-UTR. Transfection of cells with siHuR decreased both HuR protein levels and Cav-1 protein levels; conversely, ectopic overexpression of HuR via infection of cells with an adenoviral vector containing HuR cDNA (AdHuR) increased Cav-1 protein levels without disturbing Cav-1 mRNA levels. Thus, HuR enhanced Cav-1 expression in vitro by stimulating Cav-1 translation. Intestinal epithelium-specific HuR knockout in mice decreased Cav-1 protein levels without changing Cav-1 mRNA levels, consistent with the in vitro results. Decreasing the levels of HuR via siHuR transfection inhibited early epithelial repair, but this effect was reversed by ectopic overexpression of GFP-tagged Cav-1. These results indicate that posttranscriptional regulation of Cav-1 gene expression by HuR plays a critical role in the regulation of rapid epithelial repair after wounding.
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LINC00205 promotes malignancy in lung cancer by recruiting FUS and stabilizing CSDE1. Biosci Rep 2021; 40:226130. [PMID: 32808651 PMCID: PMC7536328 DOI: 10.1042/bsr20190701] [Citation(s) in RCA: 13] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/20/2019] [Revised: 08/12/2020] [Accepted: 08/17/2020] [Indexed: 12/20/2022] Open
Abstract
Lung cancer (LC) is characterized by high morbidity and mortality. Numerous long noncoding RNAs (lncRNAs) have been reported to be involved in the initiation and progression of human cancers, including LC. Long intergenic non-protein coding RNA 205 (LINC00205) is identified as a novel lncRNA, which has only been unmasked to be a potential cancer promoter in hepatocellular carcinoma and pancreatic cancer. The biologic function and the molecular mechanism of LINC00205 in LC require to be investigated. In the present study, we observed the elevated expression of LINC00205 in LC tissues and cells through real-time quantitative PCR (RT-qPCR). Additionally, silencing LINC00205 inhibited LC cell growth and migration, but aggravated cell apoptosis. Moreover, we found that LINC00205 recruited FUS to maintain the mRNA stability of cold shock domain containing E1 (CSDE1) and therefore up-regulated CSDE1 expression in LC. Further, the effects of LINC00205 on LC cell proliferation, apoptosis and migration were all erased by CSDE1 overexpression. These findings demonstrated that LINC00205 facilitates malignant phenotypes in LC by recruiting FUS to stabilize CSDE1, suggesting LINC00205 as a potential target for LC therapy.
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Seman BG, Vance JK, Akers SM, Robinson CM. Neonatal low-density granulocytes internalize and kill bacteria but suppress monocyte function using extracellular DNA. J Cell Sci 2021; 134:jcs.252528. [PMID: 33589502 DOI: 10.1242/jcs.252528] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2020] [Accepted: 02/01/2021] [Indexed: 12/26/2022] Open
Abstract
Low-density granulocytes (LDGs) are found abundantly in neonatal blood; however, there is limited mechanistic understanding of LDG interactions with bacteria and innate immune cells during acute infection. We aimed to determine how human neonatal LDGs may influence control of the bacterial burden at sites of infection, both individually and in the presence of mononuclear phagocytes. LDGs from human umbilical cord blood do phagocytose Escherichia coli O1:K1:H7 and traffic bacteria into acidic compartments. However, LDGs were significantly less efficient at bacterial uptake and killing compared to monocytes, and this activity was associated with a reduced inflammatory cytokine response. The presence of bacteria triggered the release of DNA (eDNA) from LDGs into the extracellular space that resembled neutrophil extracellular traps, but had limited anti-bacterial activity. Instead, eDNA significantly impaired monocyte control of bacteria during co-culture. These results suggest that LDG recruitment to sites of bacterial infection may compromise host protection in the neonate. Furthermore, our findings reveal novel insights into LDG activity during infection, clarify their inflammatory contributions relative to monocytes, and identify a novel LDG mechanism of immunosuppression.This article has an associated First Person interview with the first author of the paper.
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Affiliation(s)
- Brittany G Seman
- Department of Microbiology, Immunology, & Cell Biology, West Virginia University School of Medicine, Morgantown, WV 26506, USA
| | - Jordan K Vance
- Department of Microbiology, Immunology, & Cell Biology, West Virginia University School of Medicine, Morgantown, WV 26506, USA
| | - Stephen M Akers
- Department of Pediatrics, West Virginia University School of Medicine, Morgantown, WV 26506, USA
| | - Cory M Robinson
- Department of Microbiology, Immunology, & Cell Biology, West Virginia University School of Medicine, Morgantown, WV 26506, USA .,Vaccine Development Center at West Virginia University Health Sciences Center, Morgantown, WV 26506, USA
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7
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Liu J, Liu F. The Yin and Yang function of microRNAs in insulin signalling and cancer. RNA Biol 2020; 18:24-32. [PMID: 32746694 DOI: 10.1080/15476286.2020.1804236] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022] Open
Abstract
Data accumulated over the past several decades uncover a vital role of microRNAs (miRNAs) in various biological processes. It is well established that, by binding to target mRNAs, miRNAs act as post-transcription suppressors to inhibit mRNA translation and/or to promote mRNA degradation. Very recently, miRNAs have been found to act as positive regulators to promote gene transcription. In this review, we briefly summarize the regulation and functional roles of miRNAs in metabolic diseases and cancer development. We also review recent advances on the mechanisms by which miRNAs regulate gene expression, focusing on their unconventional roles as enhancers to promote gene expression. Given the high potential of miRNAs as biomarkers for risk assessment and as high-value targets for therapy, a better understanding of the Yin-Yang functional feature of miRNAs and their mechanisms of action could have significant clinical implications for the treatment of various diseases such as obesity, type 2 diabetes, and cancer.
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Affiliation(s)
- Juanhong Liu
- National Clinical Research Center for Metabolic Diseases, and Metabolic Syndrome Research Center, and Department of Metabolism and Endocrinology, The Second Xiangya Hospital, Central South University , Changsha, China
| | - Feng Liu
- National Clinical Research Center for Metabolic Diseases, and Metabolic Syndrome Research Center, and Department of Metabolism and Endocrinology, The Second Xiangya Hospital, Central South University , Changsha, China.,Departments of Pharmacology, University of Texas Health at San Antonio , San Antonio, TX, USA
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Abstract
Blastoid and pleomorphic mantle cell lymphoma (MCL) are among the worst prognostic, aggressive histology, high-risk variants of MCL, and, in this article, they are presented as blastoid MCL. Blastoid MCL have not been systematically studied, probably due to their rarity. De novo blastoid MCLs have superior outcomes compared with transformed MCL. Compared with classic MCL, extranodal involvement (mainly skin, central nervous system), frequent relapses, and inferior responses to conventional chemoimmunotherapy, BTK inhibitors and venetoclax are frequent in blastoid MCL. KTE-X19 induces excellent response in blastoid MCL. Combinations with novel agents are actively investigated. This article presents a comprehensive review on blastoid MCL in 2020.
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Affiliation(s)
- Preetesh Jain
- Department of Lymphoma/Myeloma, The University of Texas MD Anderson Cancer Center, 1515 Holcombe Boulevard, Unit 429, Houston, TX 77030, USA
| | - Michael Wang
- Department of Lymphoma/Myeloma, The University of Texas MD Anderson Cancer Center, 1515 Holcombe Boulevard, Unit 429, Houston, TX 77030, USA.
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Temporal TGF-β Supergene Family Signalling Cues Modulating Tissue Morphogenesis: Chondrogenesis within a Muscle Tissue Model? Int J Mol Sci 2020; 21:ijms21144863. [PMID: 32660137 PMCID: PMC7402331 DOI: 10.3390/ijms21144863] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/11/2020] [Revised: 07/06/2020] [Accepted: 07/07/2020] [Indexed: 12/31/2022] Open
Abstract
Temporal translational signalling cues modulate all forms of tissue morphogenesis. However, if the rules to obtain specific tissues rely upon specific ligands to be active or inactive, does this mean we can engineer any tissue from another? The present study focused on the temporal effect of “multiple” morphogen interactions on muscle tissue to figure out if chondrogenesis could be induced, opening up the way for new tissue models or therapies. Gene expression and histomorphometrical analysis of muscle tissue exposed to rat bone morphogenic protein 2 (rBMP-2), rat transforming growth factor beta 3 (rTGF-β3), and/or rBMP-7, including different combinations applied briefly for 48 h or continuously for 30 days, revealed that a continuous rBMP-2 stimulation seems to be critical to initiate a chondrogenesis response that was limited to the first seven days of culture, but only in the absence of rBMP-7 and/or rTGF-β3. After day 7, unknown modulatory effects retard rBMP-2s’ effect where only through the paired-up addition of rBMP-7 and/or rTGF-β3 a chondrogenesis-like reaction seemed to be maintained. This new tissue model, whilst still very crude in its design, is a world-first attempt to better understand how multiple morphogens affect tissue morphogenesis with time, with our goal being to one day predict the chronological order of what signals have to be applied, when, for how long, and with which other signals to induce and maintain a desired tissue morphogenesis.
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Hossain E, Habiba U, Yanagawa-Matsuda A, Alam A, Ahmed I, Towfik Alam M, Yasuda M, Higashino F. Advantages of Using Paclitaxel in Combination with Oncolytic Adenovirus Utilizing RNA Destabilization Mechanism. Cancers (Basel) 2020; 12:cancers12051210. [PMID: 32408515 PMCID: PMC7281177 DOI: 10.3390/cancers12051210] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/28/2020] [Revised: 04/29/2020] [Accepted: 05/07/2020] [Indexed: 12/17/2022] Open
Abstract
Oncolytic virotherapy is a novel approach to cancer therapy. Ad-fosARE is a conditionally replicative adenovirus engineered by inserting AU-rich elements (ARE) in the 3'-untranslated region of the E1A gene. In this study, we examined the oncolytic activity of Ad-fosARE and used it in a synergistic combination with the chemotherapeutic agent paclitaxel (PTX) for treating cancer cells. The expression of E1A was high in cancer cells due to stabilized E1A-ARE mRNA. As a result, the efficiency of its replication and cytolytic activity in cancer cells was higher than in normal cells. PTX treatment increased the cytoplasmic HuR relocalization in cancer cells, enhanced viral replication through elevated E1A expression, and upregulated CAR (Coxsackie-adenovirus receptor) required for viral uptake. Furthermore, PTX altered the instability of microtubules by acetylation and detyrosination, which is essential for viral internalization and trafficking to the nucleus. These results indicate that PTX can provide multiple advantages to the efficacy of Ad-fosARE both in vitro and in vivo, and provides a basis for designing novel clinical trials. Thus, this virus has a lot of benefits that are not found in other oncolytic viruses. The virus also has the potential for treating PXT-resistant cancers.
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Affiliation(s)
- Elora Hossain
- Department of Molecular Oncology, Faculty of Dental Medicine and Graduate School of Biomedical Science and Engineering, Hokkaido University, Sapporo 060-8638, Japan; (E.H.); (I.A.)
| | - Umma Habiba
- Department of Cancer Pathology, Faculty of Medicine, Hokkaido University, Sapporo 060-8638, Japan;
| | - Aya Yanagawa-Matsuda
- Department of Vascular Biology and Molecular Pathology, Faculty of Dental Medicine and Graduate School of Dental Medicine, Hokkaido University, Sapporo 060-8586, Japan; (A.Y.-M.); (M.T.A.)
| | - Arefin Alam
- Department of Restorative Dentistry, Faculty of Dental Medicine and Graduate School of Dental Medicine, Hokkaido University, Sapporo 060-8586, Japan;
| | - Ishraque Ahmed
- Department of Molecular Oncology, Faculty of Dental Medicine and Graduate School of Biomedical Science and Engineering, Hokkaido University, Sapporo 060-8638, Japan; (E.H.); (I.A.)
| | - Mohammad Towfik Alam
- Department of Vascular Biology and Molecular Pathology, Faculty of Dental Medicine and Graduate School of Dental Medicine, Hokkaido University, Sapporo 060-8586, Japan; (A.Y.-M.); (M.T.A.)
| | - Motoaki Yasuda
- Department of Oral Molecular Microbiology, Faculty of Dental Medicine and Graduate School of Dental Medicine, Hokkaido University, Sapporo 060-8586, Japan;
| | - Fumihiro Higashino
- Department of Molecular Oncology, Faculty of Dental Medicine and Graduate School of Biomedical Science and Engineering, Hokkaido University, Sapporo 060-8638, Japan; (E.H.); (I.A.)
- Department of Vascular Biology and Molecular Pathology, Faculty of Dental Medicine and Graduate School of Dental Medicine, Hokkaido University, Sapporo 060-8586, Japan; (A.Y.-M.); (M.T.A.)
- Correspondence: ; Tel.: +81-(0)11-706-4237
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De S, Das S, Sengupta S. Involvement of HuR in the serum starvation induced autophagy through regulation of Beclin1 in breast cancer cell-line, MCF-7. Cell Signal 2019; 61:78-85. [PMID: 31102648 DOI: 10.1016/j.cellsig.2019.05.008] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/05/2018] [Revised: 05/09/2019] [Accepted: 05/14/2019] [Indexed: 01/09/2023]
Abstract
Starvation is a cellular stress that induces autophagy, a conserved cellular self-digestion mechanism that allows cells to degrade and recycle damaged proteins and organelles. The present study illustrated that during serum deprivation, Beclin1, a crucial gene that is essential for autophagosome formation in autophagy, gets controlled post-transcriptionally in breast cancer cell-line MCF-7. RNA affinity chromatography and co-immunoprecipitation confirmed the association of HuR with 3'-UTR of beclin1 mRNA. After cytosolic translocation, HuR enhances beclin1 protein synthesis in response to serum starvation by enhancing the association of beclin1 mRNA to the polysomes. Partial silencing of HuR resulted in reduction of beclin1 expression both at mRNA and protein levels, which in turn decreased starvation-induced autophagic flux. Thus, in conclusion, fine-tuning of beclin1 gene expression at post-transcriptional level by HuR is one of the key regulatory mechanisms of starvation induced autophagy in breast cancer cell-line, MCF-7.
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Affiliation(s)
- Soumasree De
- Department of Biophysics, Molecular Biology and Bioinformatics, University of Calcutta, 92 A.P.C. Road, Kolkata 700009, India
| | - Sayantani Das
- Department of Biophysics, Molecular Biology and Bioinformatics, University of Calcutta, 92 A.P.C. Road, Kolkata 700009, India
| | - Sumita Sengupta
- Department of Biophysics, Molecular Biology and Bioinformatics, University of Calcutta, 92 A.P.C. Road, Kolkata 700009, India.
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Long noncoding RNA EGFR-AS1 promotes cell growth and metastasis via affecting HuR mediated mRNA stability of EGFR in renal cancer. Cell Death Dis 2019; 10:154. [PMID: 30770799 PMCID: PMC6377662 DOI: 10.1038/s41419-019-1331-9] [Citation(s) in RCA: 96] [Impact Index Per Article: 19.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/25/2018] [Revised: 12/15/2018] [Accepted: 01/04/2019] [Indexed: 12/22/2022]
Abstract
Long noncoding RNAs (lncRNAs) are implicated in renal cell carcinoma (RCC), but remain largely unclear. Using publicly available transcriptome sequencing data from renal cancer (n = 703) and integrating bioinformatics analyses, we screened and identified a valuable lncRNA, EGFR-AS1. In our validation cohort (n = 204), EGFR-AS1 was significantly upregulated in RCC tissues (P < 0.001). Gain-of-function and loss-of-function studies showed that EGFR-AS1 promoted cell proliferation and invasion in vitro and in vivo. Based on previous studies and sequence complementarity of EGFR with EGFR-AS1, we demonstrated that EGFR-AS1 directly bound to EGFR mRNA and inhibited its degradation. Furthermore, RNA pull-down and mass spectrometry analyses showed that EGFR-AS1 interacted with HuR, which was responsible for the mRNA stability of EGFR. Multivariate analysis suggested that higher EGFR-AS1 expression predicted a poor prognosis in RCC patients (high vs low: P = 0.018, HR = 2.204, 95% CI: 1.145-4.241). In conclusion, EGFR-AS1 enhances the malignant phenotype of RCC cells by enhancing HuR-mediated mRNA stability of EGFR. Our data also provide biological rationales for EGFR-AS1 as a prognostic biomarker and a potential therapeutic target for RCC.
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13
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RNA motifs and combinatorial prediction of interactions, stability and localization of noncoding RNAs. Nat Struct Mol Biol 2018; 25:1070-1076. [DOI: 10.1038/s41594-018-0155-0] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/01/2018] [Accepted: 10/15/2018] [Indexed: 01/16/2023]
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15
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Regulation of Postoperative Ileus by Lentivirus-Mediated HuR RNA Interference via the p38/MK2 Signaling Pathway. J Gastrointest Surg 2017; 21:389-397. [PMID: 27796636 DOI: 10.1007/s11605-016-3303-z] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/28/2016] [Accepted: 10/10/2016] [Indexed: 01/31/2023]
Abstract
OBJECTIVES The objective of the present study is to explore the effect of lentivirus-mediated HuR interference on the development and progression of postoperative ileus and the role of HuR in the regulation of the p38/MAPK-activated protein kinase-2 (MK2) signaling pathway during postoperative ileus. METHODS To establish a mouse model of lentiviral transduction, we first determined the optimum effective titer of lentiviral vectors for transduction of the murine small intestine via the abdominal cavity by using hematoxylin and eosin (HE) staining, immunohistochemistry, detection of GFP messenger RNA (mRNA) and protein, and Western blotting. To investigate the effect of HuR interference on gene expression during postoperative ileus, we established a mouse model of postoperative ileus and used RT-PCR to measure the expression of proinflammatory genes, ELISA to measure the expression of serum inflammatory cytokines, immunohistochemistry to evaluate inflammatory cell infiltration in the small intestine, HE staining of paraffin sections to examine the pathology of the small intestine, and Western blotting to measure HuR expression and identify its role in the regulation of the p38/MK2 inflammatory pathway. RESULTS We successfully designed a mouse model of intraperitoneal transduction of HuR-RNAi lentivirus. When HuR gene expression was suppressed in a mouse model of postoperative ileus, the infiltration of inflammatory cells, the expression of proinflammatory genes, and the levels of serum inflammatory cytokines were significantly reduced. This reduction in inflammation correlated with reduced cytoplasmic localization of HuR and reduced activation of MK2. CONCLUSIONS Within the p38/MK2 signal transduction pathway, HuR may increase the mRNA stability of various inflammatory cytokines, thereby promoting inflammation that causes postoperative ileus. Suppressing the expression of HuR in a postoperative ileus model can effectively suppress the postoperative ileus inflammatory reaction. HuR might serve as a candidate drug target for the prevention and mitigation of postoperative ileus.
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16
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Newman R, McHugh J, Turner M. RNA binding proteins as regulators of immune cell biology. Clin Exp Immunol 2015. [PMID: 26201441 DOI: 10.1111/cei.12684] [Citation(s) in RCA: 40] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022] Open
Abstract
Sequence-specific RNA binding proteins (RBP) are important regulators of the immune response. RBP modulate gene expression by regulating splicing, polyadenylation, localization, translation and decay of target mRNAs. Increasing evidence suggests that RBP play critical roles in the development, activation and function of lymphocyte populations in the immune system. This review will discuss the post-transcriptional regulation of gene expression by RBP during lymphocyte development, with particular focus on the Tristetraprolin family of RBP.
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Affiliation(s)
- R Newman
- Babraham Institute, Cambridge, UK
| | - J McHugh
- Babraham Institute, Cambridge, UK
| | - M Turner
- Babraham Institute, Cambridge, UK
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King PH, Chen CY. Role of KSRP in control of type I interferon and cytokine expression. J Interferon Cytokine Res 2015; 34:267-74. [PMID: 24697204 DOI: 10.1089/jir.2013.0143] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022] Open
Abstract
Cytokines and chemokines are key participants in pathways that drive inflammatory, immune, and other cellular responses to exogenous insults such as infection, trauma, and physiological stress. Persistent and aberrant expression of these factors has been linked to autoimmune, degenerative, and neoplastic diseases. Consequently, cytokine and chemokine expression is tightly governed at each level of gene regulation. Recent studies have demonstrated a role for KH-type splicing regulatory protein (KSRP) in curtailing cytokine and chemokine expression through transcriptional and post-transcriptional mechanisms, including promotion of microRNA maturation. Understanding the role of KSRP in cytokine mRNA metabolism should identify promising targets for the modulation of immune and inflammatory responses.
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Affiliation(s)
- Peter H King
- 1 Department of Neurology, University of Alabama at Birmingham , Birmingham, Alabama
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Karalok HM, Aydin E, Saglam O, Torun A, Guzeloglu-Kayisli O, Lalioti MD, Kristiansson H, Duke CMP, Choe G, Flannery C, Kallen CB, Seli E. mRNA-binding protein TIA-1 reduces cytokine expression in human endometrial stromal cells and is down-regulated in ectopic endometrium. J Clin Endocrinol Metab 2014; 99:E2610-9. [PMID: 25140393 PMCID: PMC4255110 DOI: 10.1210/jc.2013-3488] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/15/2013] [Accepted: 08/13/2014] [Indexed: 11/19/2022]
Abstract
BACKGROUND Cytokines and growth factors play important roles in endometrial function and the pathogenesis of endometriosis. mRNAs encoding cytokines and growth factors undergo rapid turnover; primarily mediated by adenosine- and uridine-rich elements (AREs) located in their 3'-untranslated regions. T-cell intracellular antigen (TIA-1), an mRNA-binding protein, binds to AREs in target transcripts, leading to decreased gene expression. OBJECTIVE The purpose of this article was to determine whether TIA-1 plays a role in the regulation of endometrial cytokine and growth factor expression during the normal menstrual cycle and whether TIA-1 expression is altered in women with endometriosis. METHODS Eutopic endometrial tissue obtained from women without endometriosis (n = 30) and eutopic and ectopic endometrial tissues from women with endometriosis (n = 17) were immunostained for TIA-1. Staining intensities were evaluated by histological scores (HSCOREs). The regulation of endometrial TIA-1 expression by immune factors and steroid hormones was studied by treating primary cultured human endometrial stromal cells (HESCs) with vehicle, lipopolysaccharide, TNF-α, IL-6, estradiol, or progesterone, followed by protein blot analyses. HESCs were engineered to over- or underexpress TIA-1 to test whether TIA-1 regulates IL-6 or TNF-α expression in these cells. RESULTS We found that TIA-1 is expressed in endometrial stromal and glandular cells throughout the menstrual cycle and that this expression is significantly higher in the perimenstrual phase. In women with endometriosis, TIA-1 expression in eutopic and ectopic endometrium was reduced compared with TIA-1 expression in eutopic endometrium of unaffected control women. Lipopolysaccharide and TNF-α increased TIA-1 expression in HESCs in vitro, whereas IL-6 or steroid hormones had no effect. In HESCs, down-regulation of TIA-1 resulted in elevated IL-6 and TNF-α expression, whereas TIA-1 overexpression resulted in decreased IL-6 and TNF-α expression. CONCLUSIONS Endometrial TIA-1 is regulated throughout the menstrual cycle, TIA-1 modulates the expression of immune factors in endometrial cells, and downregulation of TIA-1 may contribute to the pathogenesis of endometriosis.
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Affiliation(s)
- Hakan Mete Karalok
- Department of Obstetrics, Gynecology and Reproductive Sciences (H.M.K., E.A., A.T., O.G.-K., M.D.L., H.K., C.M.P.D., G.C., C.F., E.S.) and Department of Pathology (O.S.), Yale School of Medicine, New Haven, Connecticut 06520-8063; and Department of Obstetrics and Gynecology (C.B.K.), Jefferson Medical College, Thomas Jefferson University, Philadelphia, Pennsylvania 19107
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Xiao L, Wang JY. RNA-binding proteins and microRNAs in gastrointestinal epithelial homeostasis and diseases. Curr Opin Pharmacol 2014; 19:46-53. [PMID: 25063919 DOI: 10.1016/j.coph.2014.07.006] [Citation(s) in RCA: 46] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/29/2014] [Revised: 07/08/2014] [Accepted: 07/09/2014] [Indexed: 10/25/2022]
Abstract
The epithelium of gastrointestinal (GI) mucosa is a rapidly self-renewing tissue in the body, and its homeostasis is preserved through strict regulation of cell proliferation and apoptosis. Epithelial cells originate from a small number of pluripotent stem cells, which divide to either renew themselves or become committed crypt cells. RNA-binding proteins (RBPs) and microRNAs (miRNAs) regulate gene expression at the posttranscriptional level and are recently shown to modulate GI mucosal growth and repair after injury. Here we highlight the roles of RBPs HuR, CUG-binding protein 1, AU-binding factor 1, and several GI epithelial-specific miRNAs in gut mucosal homeostasis and diseases and also further analyze the mechanisms through which RBPs and miRNAs modulate the stability and translation of target mRNAs.
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Affiliation(s)
- Lan Xiao
- Cell Biology Group, Department of Surgery, University of Maryland School of Medicine, USA; Baltimore Veterans Affairs Medical Center, Baltimore, MD 21201, USA
| | - Jian-Ying Wang
- Cell Biology Group, Department of Surgery, University of Maryland School of Medicine, USA; Department of Pathology, University of Maryland School of Medicine, USA; Baltimore Veterans Affairs Medical Center, Baltimore, MD 21201, USA.
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20
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González-Feliciano JA, Hernández-Pérez M, Estrella LA, Colón-López DD, López A, Martínez M, Maurás-Rivera KR, Lasalde C, Martínez D, Araujo-Pérez F, González CI. The role of HuR in the post-transcriptional regulation of interleukin-3 in T cells. PLoS One 2014; 9:e92457. [PMID: 24658545 PMCID: PMC3962401 DOI: 10.1371/journal.pone.0092457] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/06/2013] [Accepted: 02/21/2014] [Indexed: 02/05/2023] Open
Abstract
Human Interleukin-3 (IL-3) is a lymphokine member of a class of transiently expressed mRNAs harboring Adenosine/Uridine-Rich Elements (ARE) in their 3' untranslated regions (3'-UTRs). The regulatory effects of AREs are often mediated by specific ARE-binding proteins (ARE-BPs). In this report, we show that the human IL-3 3'-UTR plays a post-transcriptional regulation role in two human transformed cell lines. More specifically, we demonstrate that the hIL-3 3'-UTR represses the translation of a luciferase reporter both in HeLa and Jurkat T-cells. These results also revealed that the hIL-3 3'-UTR-mediated translational repression is exerted by an 83 nt region comprised mainly by AREs and some non-ARE sequences. Moreover, electrophoretic mobility shift assays (EMSAs) and UV-crosslinking analysis show that this hIL-3 ARE-rich region recruits five specific protein complexes, including the ARE-BPs HuR and TIA-1. HuR binding to this ARE-rich region appears to be spatially modulated during T-cell activation. Together, these results suggest that HuR recognizes the ARE-rich region and plays a role in the IL-3 3'-UTR-mediated post-transcriptional control in T-cells.
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Affiliation(s)
- José A. González-Feliciano
- University of Puerto Rico-Río Piedras, Department of Biology, College of Natural Sciences, San Juan, Puerto Rico
| | - Marimar Hernández-Pérez
- Department of Biochemistry, University of Puerto Rico-Medical Sciences, San Juan, Puerto Rico
| | - Luis A. Estrella
- University of Puerto Rico-Río Piedras, Department of Biology, College of Natural Sciences, San Juan, Puerto Rico
| | - Daisy D. Colón-López
- University of Puerto Rico-Río Piedras, Department of Biology, College of Natural Sciences, San Juan, Puerto Rico
| | - Armando López
- University of Puerto Rico-Río Piedras, Department of Biology, College of Natural Sciences, San Juan, Puerto Rico
| | - Marina Martínez
- Department of Biochemistry, University of Puerto Rico-Medical Sciences, San Juan, Puerto Rico
| | - Kirla R. Maurás-Rivera
- University of Puerto Rico-Río Piedras, Department of Biology, College of Natural Sciences, San Juan, Puerto Rico
| | - Clarivel Lasalde
- University of Puerto Rico-Río Piedras, Department of Biology, College of Natural Sciences, San Juan, Puerto Rico
| | - Daviana Martínez
- University of Puerto Rico-Río Piedras, Department of Biology, College of Natural Sciences, San Juan, Puerto Rico
| | - Félix Araujo-Pérez
- University of Puerto Rico-Río Piedras, Department of Biology, College of Natural Sciences, San Juan, Puerto Rico
| | - Carlos I. González
- University of Puerto Rico-Río Piedras, Department of Biology, College of Natural Sciences, San Juan, Puerto Rico
- Department of Biochemistry, University of Puerto Rico-Medical Sciences, San Juan, Puerto Rico
- Molecular Sciences Research Building, San Juan, Puerto Rico
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Jeong YH, Kim Y, Song H, Chung YS, Park SB, Kim HS. Anti-inflammatory effects of α-galactosylceramide analogs in activated microglia: involvement of the p38 MAPK signaling pathway. PLoS One 2014; 9:e87030. [PMID: 24523867 PMCID: PMC3921125 DOI: 10.1371/journal.pone.0087030] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/29/2013] [Accepted: 12/17/2013] [Indexed: 12/20/2022] Open
Abstract
Microglial activation plays a pivotal role in the development and progression of neurodegenerative diseases. Thus, anti-inflammatory agents that control microglial activation can serve as potential therapeutic agents for neurodegenerative diseases. Here, we designed and synthesized α-galactosylceramide (α-GalCer) analogs to exert anti-inflammatory effects in activated microglia. We performed biological evaluations of 25 α-GalCer analogs and observed an interesting preliminary structure-activity relationship in their inhibitory influence on NO release and TNF-α production in LPS-stimulated BV2 microglial cells. After identification of 4d and 4e as hit compounds, we further investigated the underlying mechanism of their anti-inflammatory effects using RT-PCR analysis. We confirmed that 4d and 4e regulate the expression of iNOS, COX-2, IL-1β, and IL-6 at the mRNA level and the expression of TNF-α at the post-transcriptional level. In addition, both 4d and 4e inhibited LPS-induced DNA binding activities of NF-κB and AP-1 and phosphorylation of p38 MAPK without affecting other MAP kinases. When we examined the anti-inflammatory effect of a p38 MAPK-specific inhibitor, SB203580, on microglial activation, we observed an identical inhibitory pattern as that of 4d and 4e, not only on NO and TNF-α production but also on the DNA binding activities of NF-κB and AP-1. Taken together, these results suggest that p38 MAPK plays an important role in the anti-inflammatory effects of 4d and 4e via the modulation of NF-κB and AP-1 activities.
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Affiliation(s)
- Yeon-Hui Jeong
- Department of Molecular Medicine and Global Top5 Research Program, Tissue Injury Defense Research Center, Ewha Womans University Medical School, Seoul, Republic of Korea
| | - Yongju Kim
- Department of Chemistry, Seoul National University, Seoul, Republic of Korea
| | - Heebum Song
- Department of Chemistry, Seoul National University, Seoul, Republic of Korea
| | - Young Sun Chung
- Department of Counseling Psychology, Korea Soongsil Cyber University, Seoul, Republic of Korea
| | - Seung Bum Park
- Department of Chemistry, Seoul National University, Seoul, Republic of Korea
- Department of Biophysics and Chemical Biology/Bio-MAX Institute, Seoul National University, Seoul, Republic of Korea
- * E-mail: (SBP); (HSK)
| | - Hee-Sun Kim
- Department of Molecular Medicine and Global Top5 Research Program, Tissue Injury Defense Research Center, Ewha Womans University Medical School, Seoul, Republic of Korea
- * E-mail: (SBP); (HSK)
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Ciais D, Cherradi N, Feige JJ. Multiple functions of tristetraprolin/TIS11 RNA-binding proteins in the regulation of mRNA biogenesis and degradation. Cell Mol Life Sci 2013; 70:2031-44. [PMID: 22968342 PMCID: PMC11113850 DOI: 10.1007/s00018-012-1150-y] [Citation(s) in RCA: 46] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/13/2012] [Revised: 08/27/2012] [Accepted: 08/28/2012] [Indexed: 02/06/2023]
Abstract
Members of the tristetraprolin (TTP/TIS11) family are important RNA-binding proteins initially characterized as mediators of mRNA degradation. They act via their interaction with AU-rich elements present in the 3'UTR of regulated transcripts. However, it is progressively appearing that the different steps of mRNA processing and fate including transcription, splicing, polyadenylation, translation, and degradation are coordinately regulated by multifunctional integrator proteins that possess a larger panel of functions than originally anticipated. Tristetraprolin and related proteins are very good examples of such integrators. This review gathers the present knowledge on the functions of this family of RNA-binding proteins, including their role in AU-rich element-mediated mRNA decay and focuses on recent advances that support the concept of their broader involvement in distinct steps of mRNA biogenesis and degradation.
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Affiliation(s)
- Delphine Ciais
- Institut National de la Santé et de la Recherche Médicale (INSERM) U1036, 17 rue des Martyrs, 38054 Grenoble Cedex 9, France
- Commissariat à l’Energie Atomique et aux Energies Alternatives (CEA), Institut de Recherches en Technologies et Sciences pour le Vivant (iRTSV)/Biologie du Cancer et de l’Infection (BCI), 38054 Grenoble, France
- Université Joseph Fourier-Grenoble 1, 38041 Grenoble, France
| | - Nadia Cherradi
- Institut National de la Santé et de la Recherche Médicale (INSERM) U1036, 17 rue des Martyrs, 38054 Grenoble Cedex 9, France
- Commissariat à l’Energie Atomique et aux Energies Alternatives (CEA), Institut de Recherches en Technologies et Sciences pour le Vivant (iRTSV)/Biologie du Cancer et de l’Infection (BCI), 38054 Grenoble, France
- Université Joseph Fourier-Grenoble 1, 38041 Grenoble, France
| | - Jean-Jacques Feige
- Institut National de la Santé et de la Recherche Médicale (INSERM) U1036, 17 rue des Martyrs, 38054 Grenoble Cedex 9, France
- Commissariat à l’Energie Atomique et aux Energies Alternatives (CEA), Institut de Recherches en Technologies et Sciences pour le Vivant (iRTSV)/Biologie du Cancer et de l’Infection (BCI), 38054 Grenoble, France
- Université Joseph Fourier-Grenoble 1, 38041 Grenoble, France
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Moelants EAV, Mortier A, Van Damme J, Proost P. Regulation of TNF-α with a focus on rheumatoid arthritis. Immunol Cell Biol 2013; 91:393-401. [PMID: 23628802 DOI: 10.1038/icb.2013.15] [Citation(s) in RCA: 125] [Impact Index Per Article: 11.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/23/2013] [Revised: 03/21/2013] [Accepted: 03/23/2013] [Indexed: 12/13/2022]
Abstract
Cytokines and chemokines represent two important groups of proteins that control the human immune system. Dysregulation of the network in which these immunomodulators function can result in uncontrolled inflammation, leading to various diseases including rheumatoid arthritis (RA), characterized by chronic inflammation and bone erosion. Potential triggers of RA include autoantibodies, cytokines and chemokines. The tight regulation of cytokine and chemokine production, and biological activity is important. Tumor necrosis factor-α (TNF-α) is abundantly present in RA patients' serum and the arthritic synovium. This review, therefore, discusses first the role and regulation of the major proinflammatory cytokine TNF-α, in particular the regulation of TNF-α production, post-translational processing and signaling of TNF-α and its receptors. Owing to the important role of TNF-α in RA, the TNF-α-producing cells and the dynamics of its expression, the direct and indirect action of this cytokine and possible biological therapy for RA are described.
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Affiliation(s)
- Eva A V Moelants
- Laboratory of Molecular Immunology, Department of Microbiology and Immunology, Rega Institute for Medical Research, KU Leuven, Leuven, Belgium
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24
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Lancemaside A inhibits microglial activation via modulation of JNK signaling pathway. Biochem Biophys Res Commun 2013; 431:369-75. [PMID: 23348227 DOI: 10.1016/j.bbrc.2013.01.049] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/10/2013] [Accepted: 01/12/2013] [Indexed: 01/29/2023]
Abstract
Microglial activation plays an important role in neurodegenerative diseases. Thus, controlling microglial activation is considered to be a promising therapeutic target for neurodegenerative diseases. In the present study, we found that lancemaside A, a triterpenoid saponin isolated from Codonopsislanceolata, inhibited iNOS and proinflammatory cytokines in LPS-stimulated BV2 microglial cells. By analyzing molecular mechanisms underlying the anti-inflammatory effects of lancemaside A, we found that lancemaside A selectively inhibited LPS-induced JNK phosphorylation among the three types of MAP kinases. A JNK-specific inhibitor, SP600125, like lancemaside A, significantly inhibited not only NO, TNF-α, and IL-6 productions, but also NF-κB and AP-1 activities, suggesting that JNK inhibition is largely involved in the anti-inflammatory mechanism of lancemaside A. Interestingly, both the lancemaside A and SP600125 inhibited ROS production by suppressing the expression and/or phosphorylation of NADPH oxidase subunit proteins, such as p47(phox), p67(phox), and gp91(phox). The antioxidant effects of lancemaside A and SP600125 appear to be related with an increase of hemeoxygenase-1 expression by both agents. Finally, we demonstrated the neuroprotective effects of lancemaside A and SP600125 in microglia-neuron coculture systems. Collectively, our data suggest that JNK pathway plays a key role mediating anti-inflammatory effects of lancemaside A in LPS-stimulated microglia.
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25
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Lee S, Vasudevan S. Post-transcriptional stimulation of gene expression by microRNAs. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2013; 768:97-126. [PMID: 23224967 DOI: 10.1007/978-1-4614-5107-5_7] [Citation(s) in RCA: 74] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
MicroRNAs are small noncoding RNA regulatory molecules that control gene expression by guiding associated effector complexes to other RNAs via sequence-specific recognition of target sites. Misregulation of microRNAs leads to a wide range of diseases including cancers, inflammatory and developmental disorders. MicroRNAs were found to mediate deadenylation-dependent decay and translational repression of messages through partially complementary microRNA target sites in the 3'-UTR (untranslated region). A growing series of studies has demonstrated that microRNAs and their associated complexes (microRNPs) elicit alternate functions that enable stimulation of gene expression in addition to their assigned repressive roles. These reports, discussed in this chapter, indicate that microRNA-mediated effects via natural 3' and 5'-UTRs can be selective and controlled, dictated by the RNA sequence context, associated complex, and cellular conditions. Similar to the effects of repression, upregulated gene expression by microRNAs varies from small refinements to significant amplifications in expression. An emerging theme from this literature is that microRNAs have a versatile range of abilities to manipulate post-transcriptional control mechanisms leading to controlled gene expression. These studies reveal new potentials for microRNPs in gene expression control that develop as responses to specific cellular conditions.
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Khaziapoul S, Pearson MJ, Pryme IF, Stern B, Hesketh JE. CUG binding protein 1 binds to a specific region within the human albumin 3' untranslated region. Biochem Biophys Res Commun 2012; 426:539-43. [PMID: 22982313 DOI: 10.1016/j.bbrc.2012.08.123] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/07/2012] [Accepted: 08/27/2012] [Indexed: 01/28/2023]
Abstract
3' Untranslated regions (3'UTRs) of messenger RNAs have important roles in post-transcriptional regulation of gene expression and this is partly achieved through binding of specific proteins to sequences or structures within these regions. Previously, replacement of a native luciferase 3'UTR with the human albumin 3'UTR has been found to lead to a 10-fold increase in luciferase reporter activity. In this work we investigated protein binding to the human albumin 3'UTR. Electrophoretic mobility shift and UV cross-linking assays indicate that a ∼50kDa protein from Chinese Hamster Ovary (CHO) cells binds to the albumin 3'UTR, and affinity experiments followed by proteomics identified this protein as CUG binding protein 1 (CUG-BP1, also known as CELF1). Deletion analysis of the albumin 3'UTR showed that nucleotides 1-50 and nucleotides 101-150 are not required for binding but that removal of nucleotides 51-100 caused a loss in binding. The results suggest that CUG-BP1 binds to nucleotides 51-100 of the human albumin 3'UTR. In human cells CUG-BP1 binding may thus play a role in regulation of albumin expression and, additionally, it may have a function in post-transcriptional control in CHO cells.
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Affiliation(s)
- Siavash Khaziapoul
- Institute for Cell and Molecular Biosciences, The Medical School, Newcastle University, Framlington Place, Newcastle upon Tyne, NE2 4HH, UK
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Pearson MJ, Khazaipoul S, Optun A, Pryme IF, Stern B, Hesketh JE. Albumin 3'untranslated region facilitates increased recombinant protein production from Chinese hamster ovary cells. Biotechnol J 2012; 7:1405-11. [PMID: 22623341 DOI: 10.1002/biot.201200044] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/27/2012] [Revised: 04/24/2012] [Accepted: 05/21/2012] [Indexed: 11/07/2022]
Abstract
Chinese hamster ovary (CHO) cells are used for recombinant protein production in the pharmaceutical industry but there is a need to improve expression levels. In the present work experiments were carried out to test the effectiveness of different 3'untranslated regions (3'UTRs) in promoting production of a naturally secreted luciferase. Seamless cloning was used to produce expression vectors in which Gaussia princeps luciferase coding sequences were linked to the human albumin, immunoglobulin or chymotrypsinogen 3'UTR. Stably transfected CHO cells expressing these constructs were selected. Luciferase activity in the culture medium was increased 2-3-fold by replacing the endogenous 3'UTR with the albumin 3'UTR and decreased by replacement with immunoglobulin or chymotrypsinogen 3'UTR. Replacement of the native 3'UTR with the albumin 3'UTR led to a 10-fold increase in luciferase mRNA levels. Deletion analysis of the albumin 3'UTR showed that loss of nucleotides 1-50, which removed an AU-rich complex stem loop region, caused significant reductions in both luciferase protein expression and luciferase mRNA levels. The results suggest that recombinant protein expression and yield could be improved by the careful selection of appropriate 3'UTR sequences.
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Affiliation(s)
- Mark J Pearson
- Institute for Cell and Molecular Biosciences, The Medical School, Newcastle University, Framlington Place, Newcastle upon Tyne, UK
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28
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Clément Y, Prut L, Saurini F, Mineur YS, Le Guisquet AM, Védrine S, Andres C, Vodjdani G, Belzung C. Gabra5-gene haplotype block associated with behavioral properties of the full agonist benzodiazepine chlordiazepoxide. Behav Brain Res 2012; 233:474-82. [PMID: 22677273 DOI: 10.1016/j.bbr.2012.05.041] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/25/2012] [Revised: 05/21/2012] [Accepted: 05/25/2012] [Indexed: 01/09/2023]
Abstract
The gabra5 gene is associated with pharmacological properties (myorelaxant, amnesic, anxiolytic) of benzodiazepines. It is tightly located (0.5 cM) close to the pink-eyed dilution (p) locus which encodes for fur color on mouse chromosome 7. We tested the putative role of the gabra5 gene in pharmacological properties of the full non specific agonist chlordiazepoxide (CDP), using behavioral and molecular approaches in mutated p/p mice and wild type F2 from crosses between two multiple markers inbred strain ABP/Le and C57BL/6By strain. From our results, using rotarod, light-dark box, elevated maze and radial arm maze tests, we demonstrate that p/p mice are more sensitive than WT to the sensory motor, anxiolytic and amnesic effect of CDP. This is associated with the presence of a haplotypic block on the murine chromosome 7 and with an up regulation of gabra5 mRNAs in hippocampi of p/p F2 mice.
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Affiliation(s)
- Y Clément
- Centre de Recherche de l'Institut du Cerveau et de la Moelle Epinière, 75651 Paris Cedex, France.
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Letonqueze O, Lee J, Vasudevan S. MicroRNA-mediated posttranscriptional mechanisms of gene expression in proliferating and quiescent cancer cells. RNA Biol 2012; 9:871-80. [PMID: 22699554 DOI: 10.4161/rna.20806] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023] Open
Abstract
MicroRNAs are small non-coding RNA regulators of gene expression that play important roles in critical biological processes, including cell division, self-renewal and cell state maintenance. Their deregulation leads to extensive clinical consequences in tumorigenesis. Cancers demonstrate heterogeneity in their cell states implicated in their resistance and resurgence. Apart from proliferating cells, cancers harbor a small proportion of assorted quiescent cells that resist conventional therapeutics and contribute to cancer recurrence. MicroRNA expression, targets, microRNPs (microRNA-protein complexes) and their functions have been demonstrated to be regulated in distinct tumor cell states and as an adaptive response to stress signals in tumor-unfavorable environments. In turn, altered microRNPs and their modified post-transcriptional mechanisms of gene expression may contribute to tumor resistance and influence tumor progression. An understanding of distinct microRNA mechanisms in cancer cells would provide extensive insights into the versatile roles of microRNAs in the perpetuation of tumors and indicate potential therapeutic avenues.
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Affiliation(s)
- Olivier Letonqueze
- Cancer Center, Massachusetts General Hospital, Harvard Medical School, Boston, MA, USA
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Slotta-Huspenina J, Koch I, de Leval L, Keller G, Klier M, Bink K, Kremer M, Raffeld M, Fend F, Quintanilla-Martinez L. The impact of cyclin D1 mRNA isoforms, morphology and p53 in mantle cell lymphoma: p53 alterations and blastoid morphology are strong predictors of a high proliferation index. Haematologica 2012; 97:1422-30. [PMID: 22315488 DOI: 10.3324/haematol.2011.055715] [Citation(s) in RCA: 51] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022] Open
Abstract
BACKGROUND Mantle cell lymphoma is a clinically heterogeneous disease characterized by overexpression of cyclin D1 protein. Blastoid morphology, high proliferation, and secondary genetic aberrations are markers of aggressive behavior. Expression profiling of mantle cell lymphoma revealed that predominance of the 3'UTR-deficient, short cyclin D1 mRNA isoform was associated with high cyclin D1 levels, a high "proliferation signature" and poor prognosis. DESIGN AND METHODS Sixty-two cases of mantle cell lymphoma were analyzed for cyclin D1 mRNA isoforms and total cyclin D1 levels by real-time reverse transcriptase polymerase chain reaction, and TP53 alterations were assessed by immunohistochemistry and molecular analysis. Results were correlated with proliferation index and clinical outcome. RESULTS Predominance of the short cyclin D1 mRNA was found in 14 (23%) samples, including four with complete loss of the standard transcript. TP53 alterations were found in 15 (24%) cases. Predominance of 3'UTR-deficient mRNA was significantly associated with high cyclin D1 mRNA levels (P=0.009) and more commonly found in blastoid mantle cell lymphoma (5/11, P=0.060) and cases with a proliferation index of >20% (P=0.026). Both blastoid morphology (11/11, P<0.001) and TP53 alterations (15/15, P<0.001) were significantly correlated with a high proliferation index. A proliferation index of 10% was determined to be a significant threshold for survival in multivariate analysis (P=0.01). CONCLUSIONS TP53 alterations are strongly associated with a high proliferation index and aggressive behavior in mantle cell lymphoma. Predominance of the 3'UTR-deficient transcript correlates with higher cyclin D1 levels and may be a secondary contributing factor to high proliferation, but failed to reach prognostic significance in this study.
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Affiliation(s)
- Julia Slotta-Huspenina
- Institute of Pathology, University Hospital Tübingen, Liebermeisterstrasse 8, D-72076 Tübingen, Germany
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Vasudevan S. Posttranscriptional upregulation by microRNAs. WILEY INTERDISCIPLINARY REVIEWS-RNA 2011; 3:311-30. [PMID: 22072587 DOI: 10.1002/wrna.121] [Citation(s) in RCA: 321] [Impact Index Per Article: 24.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Abstract
MicroRNAs are small non-coding RNA guide molecules that regulate gene expression via association with effector complexes and sequence-specific recognition of target sites on other RNAs; misregulated microRNA expression and functions are linked to a variety of tumors, developmental disorders, and immune disease. MicroRNAs have primarily been demonstrated to mediate posttranscriptional downregulation of expression; translational repression, and deadenylation-dependent decay of messages through partially complementary microRNA target sites in mRNA untranslated regions (UTRs). However, an emerging assortment of studies, discussed in this review, reveal that microRNAs and their associated protein complexes (microribonucleoproteins or microRNPs) can additionally function to posttranscriptionally stimulate gene expression by direct and indirect mechanisms. These reports indicate that microRNA-mediated effects can be selective, regulated by the RNA sequence context, and associated with RNP factors and cellular conditions. Like repression, translation upregulation by microRNAs has been observed to range from fine-tuning effects to significant alterations in expression. These studies uncover remarkable, new abilities of microRNAs and associated microRNPs in gene expression control and underscore the importance of regulation, in cis and trans, in directing appropriate microRNP responses.
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Di Giammartino DC, Nishida K, Manley JL. Mechanisms and consequences of alternative polyadenylation. Mol Cell 2011; 43:853-66. [PMID: 21925375 DOI: 10.1016/j.molcel.2011.08.017] [Citation(s) in RCA: 544] [Impact Index Per Article: 41.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/28/2011] [Revised: 08/02/2011] [Accepted: 08/09/2011] [Indexed: 12/11/2022]
Abstract
Alternative polyadenylation (APA) is emerging as a widespread mechanism used to control gene expression. Like alternative splicing, usage of alternative poly(A) sites allows a single gene to encode multiple mRNA transcripts. In some cases, this changes the mRNA coding potential; in other cases, the code remains unchanged but the 3' UTR length is altered, influencing the fate of mRNAs in several ways, for example, by altering the availability of RNA binding protein sites and microRNA binding sites. The mechanisms governing both global and gene-specific APA are only starting to be deciphered. Here we review what is known about these mechanisms and the functional consequences of alternative polyadenylation.
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Abstract
Messenger RNAs (mRNAs) contain prominent untranslated regions (UTRs) that are increasingly recognized to play roles in mRNA processing, transport, stability, and translation. 3' UTRs are believed to harbor recognition sites for a diverse set of RNA-binding proteins that regulate gene expression as well as most active microRNA target sites. Although the roles of 3' UTRs in the normal and diseased lung have not yet been studied extensively, available evidence suggests important roles for 3' UTRs in lung development, inflammation, asthma, pulmonary fibrosis, and cancer. Systematic, genome-wide approaches are beginning to catalog functional elements within 3' UTRs and identify the proteins and microRNAs that interact with these elements. Application of new data sets and experimental approaches should provide powerful insights into how 3' UTR-mediated regulatory events contribute to disease and may inspire novel therapeutic approaches.
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Zhang J, Bowden GT. Activation of p38 MAP kinase and JNK pathways by UVA irradiation. Photochem Photobiol Sci 2011; 11:54-61. [PMID: 21858326 DOI: 10.1039/c1pp05133d] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
There are more than two million new cases of non-melanoma skin cancers (NMSCs) diagnosed each year in the United States of America. The clear etiological factor is chronic exposure to solar radiation from the sun. The wavelengths of solar light that reach the earth's surface include UVB (280-320 nm), which accounts for 1-10%, and UVA (320-400 nm), which accounts for 90-99% of the radiation. While most published research has focused on the effects of UVB, little is known concerning UVA-mediated signal transduction pathways, and their role in skin tumor promotion and progression, giving rise to squamous cell carcinomas (SCCs). Here, we focus on UVA-mediated activation of p38 MAP kinase and c-Jun N-terminal kinase (JNK), and their roles in activator protein-1 (AP-1) mediated transcription, cyclooxygenase-2 (COX-2) and Bcl-XL expression. Since p38 MAP kinase and JNK play major roles in the expression of UVA-induced AP-1, COX-2 and Bcl-XL, pharmacological inhibitors of these kinases may be useful in the chemoprevention of SCC skin cancer.
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Affiliation(s)
- Jack Zhang
- Department of Medical Pharmacology, University of Arizona, Tucson, Arizona, USA
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von Knethen A, Neb H, Morbitzer V, Schmidt MV, Kuhn AM, Kuchler L, Brüne B. PPARγ stabilizes HO-1 mRNA in monocytes/macrophages which affects IFN-β expression. Free Radic Biol Med 2011; 51:396-405. [PMID: 21571064 DOI: 10.1016/j.freeradbiomed.2011.04.033] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/29/2010] [Revised: 03/29/2011] [Accepted: 04/18/2011] [Indexed: 01/02/2023]
Abstract
NADPH oxidase activation in either RAW264.7 cells or peritoneal macrophages (PM) derived from PPARγ wild-type mice increased reactive oxygen species (ROS) formation, caused PPARγ activation, heme oxygenase-1 (HO-1) induction, and concomitant IFN-β expression. In macrophages transduced with a dominant negative (d/n) mutant of PPARγ (RAW264.7 AF2) as well as PPARγ negative PM derived from Mac-PPARγ-KO mice, NADPH oxidase-dependent IFN-β expression was attenuated. As the underlying mechanism, we noted decreased HO-1 mRNA stability in RAW264.7 AF2 cells as well as PPARγ negative PM, compared to either parent RAW264.7 cells or wild-type PM. Assuming mRNA stabilization of HO-1 by PPARγ we transfected macrophages with a HO-1 3'-UTR reporter construct. The PPARγ agonist rosiglitazone significantly up-regulated luciferase expression in RAW264.7 cells, while it remained unaltered in RAW264.7 AF2 macrophages. Deletion of each of two AU-rich elements in the 3'-UTR HO-1 decreased luciferase activity in RAW264.7 cells. Using LPS as a NADPH oxidase activator, PM from Mac-PPARγ-KO mice showed a decreased HO-1 mRNA half-life in vitro and in vivo compared to PPARγ wild-type mice. These data identified a so far unappreciated role of PPARγ in stabilizing HO-1 mRNA, thus, contributing to the expression of the HO-1 target gene IFN-β.
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Affiliation(s)
- Andreas von Knethen
- Institute of Biochemistry I-Pathobiochemistry, Faculty of Medicine, Goethe-University Frankfurt, 60590 Frankfurt, Theodor-Stern-Kai 7, Germany.
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Idler RK, Yan W. Control of messenger RNA fate by RNA-binding proteins: an emphasis on mammalian spermatogenesis. ACTA ACUST UNITED AC 2011; 33:309-37. [PMID: 21757510 DOI: 10.2164/jandrol.111.014167] [Citation(s) in RCA: 81] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Abstract
Posttranscriptional status of messenger RNAs (mRNA) can be affected by many factors, most of which are RNA-binding proteins (RBP) that either bind mRNA in a nonspecific manner or through specific motifs, usually located in the 3' untranslated regions. RBPs can also be recruited by small noncoding RNAs (sncRNA), which have been shown to be involved in posttranscriptional regulations and transposon repression (eg, microRNAs or P-element-induced wimpy testis-interacting RNA) as components of the sncRNA effector complex. Non-sncRNA-binding RBPs have much more diverse effects on their target mRNAs. Some can cause degradation of their target transcripts and/or repression of translation, whereas others can stabilize and/or activate translation. The splicing and exportation of transcripts from the nucleus to the cytoplasm are often mediated by sequence-specific RBPs. The mechanisms by which RBPs regulate mRNA transcripts involve manipulating the 3' poly(A) tail, targeting the transcript to polysomes or to other ribonuclear protein particles, recruiting regulatory proteins, or competing with other RBPs. Here, we briefly review the known mechanisms of posttranscriptional regulation mediated by RBPs, with an emphasis on how these mechanisms might control spermatogenesis in general.
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Affiliation(s)
- R Keegan Idler
- Department of Physiology and Cell Biology, University of Nevada School of Medicine, Reno, NV 89557, USA
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Khan MI, Islam N, Sahasrabuddhe AA, Mahdi AA, Siddiqui H, Ashquin M, Ahmad I. Ubiquitous hazardous metal lead induces TNF-α in human phagocytic THP-1 cells: primary role of ERK 1/2. JOURNAL OF HAZARDOUS MATERIALS 2011; 189:255-264. [PMID: 21377791 DOI: 10.1016/j.jhazmat.2011.02.027] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/03/2010] [Revised: 02/11/2011] [Accepted: 02/11/2011] [Indexed: 05/30/2023]
Abstract
Induction of tumor necrosis factor-α (TNF-α) in response to lead (Pb) exposure has been implicated in its immunotoxicity. However, the molecular mechanism by which Pb upregulates the level of TNF-α is wagely known. An attempt was therefore made to elucidate the mechanistic aspect of TNF-α induction, mainly focusing transcriptional and post transcriptional regulation via mitogen activated protein kinases (MAPKs) activation. We observed that exposure of Pb to human monocytic THP-1 cells resulted in significant enhanced production of TNF-α m-RNA and protein secretion. Moreover, the stability of TNF-α m-RNA was also increased as indicated by its half life. Notably, activation of ERK 1/2, p38 and JNK in Pb exposed THP-1 was also evident. Specific inhibitor of ERK1/2, PD 98059 caused significant inhibition in production and stability of TNF-α m-RNA. However, SB 203580 partially inhibited production and stability of TNF-α m-RNA. Interestingly, a combined exposure of these two inhibitors completely blocked modulation of TNF-α m-RNA. Data tends to suggest that expression and stability of TNF-α induction due to Pb exposure is mainly regulated through ERK. Briefly, these observations are useful in understanding some mechanistic aspects of proinflammatory and immunotoxicity of Pb, a globally acknowledged key environmental contaminant.
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Affiliation(s)
- Mohd Imran Khan
- Fiber Toxicology Division, Indian Institute of Toxicology Research, Council of Scientific & Industrial Research, Mahatma Gandhi Marg, PO Box 80, Lucknow 226001, UP, India
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Fath S, Bauer AP, Liss M, Spriestersbach A, Maertens B, Hahn P, Ludwig C, Schäfer F, Graf M, Wagner R. Multiparameter RNA and codon optimization: a standardized tool to assess and enhance autologous mammalian gene expression. PLoS One 2011; 6:e17596. [PMID: 21408612 PMCID: PMC3048298 DOI: 10.1371/journal.pone.0017596] [Citation(s) in RCA: 110] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/14/2010] [Accepted: 01/30/2011] [Indexed: 01/31/2023] Open
Abstract
Autologous expression of recombinant human proteins in human cells for biomedical research and product development is often hampered by low expression yields limiting subsequent structural and functional analyses. Following RNA and codon optimization, 50 candidate genes representing five classes of human proteins – transcription factors, ribosomal and polymerase subunits, protein kinases, membrane proteins and immunomodulators – all showed reliable, and 86% even elevated expression. Analysis of three representative examples showed no detrimental effect on protein solubility while unaltered functionality was demonstrated for JNK1, JNK3 and CDC2 using optimized constructs. Molecular analysis of a sequence-optimized transgene revealed positive effects at transcriptional, translational, and mRNA stability levels. Since improved expression was consistent in HEK293T, CHO and insect cells, it was not restricted to distinct mammalian cell systems. Additionally, optimized genes represent powerful tools in functional genomics, as demonstrated by the successful rescue of an siRNA-mediated knockdown using a sequence-optimized counterpart. This is the first large-scale study addressing the influence of multiparameter optimization on autologous human protein expression.
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Affiliation(s)
| | - Asli Petra Bauer
- Molecular Microbiology and Gene Therapy Unit, Institute of Medical Microbiology and Hygiene, University of Regensburg, Regensburg, Germany
| | | | | | | | | | | | | | | | - Ralf Wagner
- Geneart AG, BioPark, Regensburg, Germany
- Molecular Microbiology and Gene Therapy Unit, Institute of Medical Microbiology and Hygiene, University of Regensburg, Regensburg, Germany
- * E-mail:
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Karipcin FS, Ensari TA, Kayisli UA, Guzel E, Kallen CB, Seli E. The mRNA-binding protein HuR is regulated in the menstrual cycle and repressed in ectopic endometrium. Reprod Sci 2011; 18:145-55. [PMID: 20889954 PMCID: PMC3343139 DOI: 10.1177/1933719110382307] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/01/2023]
Abstract
Cytokines modulate turnover of the endometrium during the menstrual cycle and contribute to the pathogenesis of endometriosis. Gene expression for cytokines is often regulated by proteins that bind to adenosine- and uridine-rich elements (AREs) in their transcripts to stabilize or destabilize bound messenger RNAs (mRNAs). HuR/ELAVL1 is an RNA-binding protein that stabilizes ARE-containing mRNAs. We hypothesized that HuR might play a role in regulating cytokine expression during the menstrual cycle and in endometriosis and characterized the expression and regulation of HuR in eutopic and ectopic human endometrium. Tissue sections obtained from normal (n = 23) and ectopic (n = 16) endometrium were immunostained for HuR, and staining intensity was evaluated by HSCORE. Cultured stromal cells isolated from normal endometrium were treated with vehicle, estradiol (E2), progesterone (P), E2 + P, tumor necrosis factor-α (TNF-α), and interleukin 1β (IL-1β) for 24 hours, and HuR expression was determined by Western blot. HuR immunoreactivity was significantly lower in the early proliferative and late secretory phases (157.5 ± 11.08 and 190.0 ± 15.2, respectively), compared to the mid-late proliferative (270.0 ± 8.0) and early-mid secretory phases (256.6 ± 20.2; P < .01, analysis of variance [ANOVA]). Furthermore, HuR expression was significantly lower in ectopic endometrial cells compared to normal endometrium in mid-late proliferative and early-mid-secretory phases (P < .01). Estrogen, P, or cytokines did not alter HuR expression in cultured endometrial stromal cells. Increased HuR levels in the mid-menstrual phases are likely to contribute to reduced mid-cycle cytokine expression and enhanced cellular survival in eutopic endometrium. In ectopic endometrium, elevated cytokine levels associated with endometriosis likely reduce HuR expression.
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Affiliation(s)
- Fethiye Sinem Karipcin
- Department of Obstetrics, Gynecology and Reproductive Sciences, Yale University School of Medicine, New Haven, CT, USA
- Currently at the Department of Obstetrics & Gynecology, The University of Texas Medical Branch, Galveston, TX, USA
| | - Tugba Altun Ensari
- Department of Obstetrics, Gynecology and Reproductive Sciences, Yale University School of Medicine, New Haven, CT, USA
- Currently at the Etlik Zubeyde Hanim Women’s Health Teaching and Research Hospital, Department of Obstetrics and Gynecology, Ankara, Turkey
| | - Umit A. Kayisli
- Department of Obstetrics, Gynecology and Reproductive Sciences, Yale University School of Medicine, New Haven, CT, USA
| | - Elif Guzel
- Department of Obstetrics, Gynecology and Reproductive Sciences, Yale University School of Medicine, New Haven, CT, USA
| | - Caleb B. Kallen
- Department of Gynecology and Obstetrics, Emory University School of Medicine, Atlanta, GA, USA
| | - Emre Seli
- Department of Obstetrics, Gynecology and Reproductive Sciences, Yale University School of Medicine, New Haven, CT, USA
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Fujimori C, Ogiwara K, Hagiwara A, Rajapakse S, Kimura A, Takahashi T. Expression of cyclooxygenase-2 and prostaglandin receptor EP4b mRNA in the ovary of the medaka fish, Oryzias latipes: possible involvement in ovulation. Mol Cell Endocrinol 2011; 332:67-77. [PMID: 20932877 DOI: 10.1016/j.mce.2010.09.015] [Citation(s) in RCA: 50] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/19/2010] [Revised: 08/18/2010] [Accepted: 09/28/2010] [Indexed: 10/19/2022]
Abstract
In vitro ovulation of mature medaka ovarian follicles was inhibited by inhibitors of cyclooxygenase (COX) or by an antagonist of the prostaglandin E(2) receptor (EP). Of the three medaka COX genes, ptgs2 was most dominantly expressed in the fish ovary. The ptgs2 transcript was detected in all sizes of growing follicles. In a 24-h spawning cycle, large-sized follicles contained ptgs2 mRNA at a fairly constant level. The levels of COX enzyme activity and prostaglandin E(2) were also constant in the large-sized follicles during the spawning cycle. The expression of prostaglandin E(2) receptor EP4b (ptger4b) mRNA was drastically upregulated in the large-sized follicles as the ovulation time approached. The current results indicate that prostaglandin E(2), which might be produced by COX-2, is involved in the ovulation of medaka, and that EP4b is likely the receptor responsible for exerting the action of prostaglandin E(2) in the process.
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Affiliation(s)
- Chika Fujimori
- Laboratory of Reproductive and Developmental Biology, Faculty of Science, Hokkaido University, Sapporo 060-0810, Japan
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Turner M. Is transcription the dominant force during dynamic changes in gene expression? ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2011; 780:1-13. [PMID: 21842360 DOI: 10.1007/978-1-4419-5632-3_1] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/09/2022]
Abstract
Dynamic changes in gene expression punctuate lymphocyte development and are a characteristic of lymphocyte activation. A prevailing view has been that these changes are driven by DNA transcription factors, which are the dominant force in gene expression. Accumulating evidence is challenging this DNA centric view and has highlighted the prevalence and dynamic nature of RNA handling mechanisms. Alternative splicing and differential polyadenylation appear to be more widespread than first thought. Changes in mRNA decay rates also affect the abundance of transcripts and this mechanism may contribute significantly to gene expression. Additional RNA handling mechanisms that control the intracellular localization of mRNA and association with translating ribosomes are also important. Thus, gene expression is regulated through the coordination of transcriptional and post-transcriptional mechanisms. Developing a more "RNA centric" view of gene expression will allow a more systematic understanding of how gene expression and cell function are integrated.
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Affiliation(s)
- Martin Turner
- The Babraham Institute, Babraham, Cambridge, CB22 3AT, UK.
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42
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Xiao L, Wang JY. Posttranscriptional regulation of gene expression in epithelial cells by polyamines. Methods Mol Biol 2011; 720:67-79. [PMID: 21318867 DOI: 10.1007/978-1-61779-034-8_4] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/30/2023]
Abstract
In addition to regulating gene transcription, polyamines also potently modulate gene expression posttranscriptionally. Posttranscriptional gene regulation, which includes processes such as mRNA transport, turnover, and translation, involves specific mRNA sequences (cis-element) that interact with transacting factors such as RNA-binding proteins (RBPs) and microRNAs. U- or AU-rich elements (ARE) are the best characterized cis-acting sequences located in the 3'-untranslated regions of many labile mRNAs. Several RBPs, including AUF1, BRF1, TTP, and KSRP, promote ARE-mRNA decay through the recruitment of the ARE-bearing mRNA to sites of mRNA degradation, whereas RBPs such as HuR, HuB, HuC, and HuD stabilize target mRNAs and stimulate their translation. HuR is one of the best-studied RBPs and has emerged as a key regulator of posttranscriptional control of gene expression and its activity is tightly regulated by cellular polyamines. Ribonucleoprotein immunoprecipitation assays and biotin pull-down assays are two major methods used extensively in experiments investigating the roles and mechanisms of cellular polyamines in the posttranscriptional regulation and are described in detail in this chapter.
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Affiliation(s)
- Lan Xiao
- Baltimore Veterans Affairs Medical Center, Baltimore, MD, USA
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Ahmed F, Benedito VA, Zhao PX. Mining Functional Elements in Messenger RNAs: Overview, Challenges, and Perspectives. FRONTIERS IN PLANT SCIENCE 2011; 2:84. [PMID: 22639614 PMCID: PMC3355573 DOI: 10.3389/fpls.2011.00084] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/31/2011] [Accepted: 11/03/2011] [Indexed: 05/03/2023]
Abstract
Eukaryotic messenger RNA (mRNA) contains not only protein-coding regions but also a plethora of functional cis-elements that influence or coordinate a number of regulatory aspects of gene expression, such as mRNA stability, splicing forms, and translation rates. Understanding the rules that apply to each of these element types (e.g., whether the element is defined by primary or higher-order structure) allows for the discovery of novel mechanisms of gene expression as well as the design of transcripts with controlled expression. Bioinformatics plays a major role in creating databases and finding non-evident patterns governing each type of eukaryotic functional element. Much of what we currently know about mRNA regulatory elements in eukaryotes is derived from microorganism and animal systems, with the particularities of plant systems lagging behind. In this review, we provide a general introduction to the most well-known eukaryotic mRNA regulatory motifs (splicing regulatory elements, internal ribosome entry sites, iron-responsive elements, AU-rich elements, zipcodes, and polyadenylation signals) and describe available bioinformatics resources (databases and analysis tools) to analyze eukaryotic transcripts in search of functional elements, focusing on recent trends in bioinformatics methods and tool development. We also discuss future directions in the development of better computational tools based upon current knowledge of these functional elements. Improved computational tools would advance our understanding of the processes underlying gene regulations. We encourage plant bioinformaticians to turn their attention to this subject to help identify novel mechanisms of gene expression regulation using RNA motifs that have potentially evolved or diverged in plant species.
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Affiliation(s)
- Firoz Ahmed
- Bioinformatics Laboratory, Plant Biology Division, Samuel Roberts Noble FoundationArdmore, OK, USA
| | - Vagner A. Benedito
- Genetics and Developmental Biology, Plant and Soil Sciences Division, West Virginia UniversityMorgantown, WV, USA
| | - Patrick Xuechun Zhao
- Bioinformatics Laboratory, Plant Biology Division, Samuel Roberts Noble FoundationArdmore, OK, USA
- *Correspondence: Patrick Xuechun Zhao, Bioinformatics Laboratory, Plant Biology Division, Samuel Roberts Noble Foundation, 2510 Sam Noble Parkway, Ardmore, OK 73401, USA e-mail:
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Abstract
Chronic wounds represent a major and rising socioeconomic threat affecting over 6.5 million people in the United States costing in excess of US $25 billion annually. Wound healing is a physiological response to injury that is conserved across tissue systems. In humans, wounding is followed by instant response aimed at hemostasis, which in turn provides the foundation for inflammatory processes that closely follow. Inflammation is helpful and a prerequisite for healing as long as it is mounted and resolved in a timely manner. Chronic inflammation derails the healing cascade resulting in impaired wound closure. Disruption of Dicer, the RNase III enzyme that generates functional miRNAs, has a major impact on the overall immune system. Emerging studies indicate that miRNAs, especially miR-21, miR-146a/b, and miR-155, play a key role in regulating several hubs that orchestrate the inflammatory process. Direct evidence from studies addressing wound inflammation being limited, the current work represents a digest of the relevant literature that is aimed at unveiling the potential significance of miRNAs in the regulation of wound inflammation. Such treatment would help establish new paradigms highlighting a central role of miRs in the understanding and management of dysregulated inflammation as noted in conjunction with chronic wounds.
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Affiliation(s)
- Sashwati Roy
- Comprehensive Wound Center and Davis Heart and Lung Research Institute, Department of Surgery, The Ohio State University Medical Center, Columbus, Ohio 43210, USA.
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45
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Bak RO, Mikkelsen JG. Regulation of cytokines by small RNAs during skin inflammation. J Biomed Sci 2010; 17:53. [PMID: 20594301 PMCID: PMC2905360 DOI: 10.1186/1423-0127-17-53] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/03/2010] [Accepted: 07/01/2010] [Indexed: 02/08/2023] Open
Abstract
Intercellular signaling by cytokines is a vital feature of the innate immune system. In skin, an inflammatory response is mediated by cytokines and an entwined network of cellular communication between T-cells and epidermal keratinocytes. Dysregulated cytokine production, orchestrated by activated T-cells homing to the skin, is believed to be the main cause of psoriasis, a common inflammatory skin disorder. Cytokines are heavily regulated at the transcriptional level, but emerging evidence suggests that regulatory mechanisms that operate after transcription play a key role in balancing the production of cytokines. Herein, we review the nature of cytokine signaling in psoriasis with particular emphasis on regulation by mRNA destabilizing elements and the potential targeting of cytokine-encoding mRNAs by miRNAs. The proposed linkage between mRNA decay mediated by AU-rich elements and miRNA association is described and discussed as a possible general feature of cytokine regulation in skin. Moreover, we describe the latest attempts to therapeutically target cytokines at the RNA level in psoriasis by exploiting the cellular RNA interference machinery. The applicability of cytokine-encoding mRNAs as future clinical drug targets is evaluated, and advances and obstacles related to topical administration of RNA-based drugs targeting the cytokine circuit in psoriasis are described.
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Affiliation(s)
- Rasmus O Bak
- Department of Human Genetics, University of Aarhus, DK-8000 Aarhus C, Denmark
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The RNA-binding zinc-finger protein tristetraprolin regulates AU-rich mRNAs involved in breast cancer-related processes. Oncogene 2010; 29:4205-15. [PMID: 20498646 DOI: 10.1038/onc.2010.168] [Citation(s) in RCA: 86] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
Tristetraprolin (TTP or ZFP36) is a tandem CCCH zinc-finger RNA-binding protein that regulates the stability of certain AU-rich element (ARE) mRNAs. Recent work suggests that TTP is deficient in cancer cells when compared with normal cell types. In this study we found that TTP expression was lower in invasive breast cancer cells (MDAMB231) compared with normal breast cell lines MCF12A and MCF-10. TTP targets were probed using a novel approach by expressing the C124R zinc-finger TTP mutant that functions as dominant negative and increases target mRNA expression. In contrast to wild-type TTP, C124R TTP was able to increase certain ARE-mRNA expressions in serum-stimulated breast cancer cells. Using an ARE-gene microarray, novel targets of TTP regulation were identified, namely, urokinase plasminogen activator (uPA), uPA receptor and matrix metalloproteinase-1, all known to have prominent roles in breast cancer invasion and metastasis. Expression of these targets was upregulated in tumorigenic types, particularly in highly invasive MDAMB231. The mRNA half-lives of these TTP-regulated genes were increased in TTP-knockout embryonic mouse fibroblasts, as assessed using real-time polymerase chain reaction, whereas forced restoration of TTP by transfection led to a reduction in their mRNA levels. RNA immunoprecipitation confirmed an association of TTP, but not C124R, with these target transcripts. Moreover, TTP reduced, whereas the mutant C124R TTP increased, the activity of reporter constructs fused to target ARE. As a result of TTP regulation, invasiveness of MDAMB231 cells was reduced. The data suggest that TTP, in a 3' untranslated region-and ARE-dependent manner, regulates an important subset of cancer-related genes that are involved in cellular growth, invasion and metastasis.
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Toll-like receptor-induced reactivity and strongly potentiated IL-8 production in granulocytes mobilized for transfusion purposes. Blood 2010; 115:4588-96. [PMID: 20354173 DOI: 10.1182/blood-2009-11-253245] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022] Open
Abstract
Transfusion of granulocytes from granulocyte-colony stimulating factor (G-CSF)/dexamethasone (dexa)-treated donors can be beneficial for neutropenic recipients that are refractory to antimicrobial therapy. G-CSF/dexa treatment not only increases the number of circulating neutrophils but also affects their gene expression. Because of the intended transfusion of these granulocytes into patients who are severely ill, it is of importance to establish to what extent mobilization affects the cellular behavior of neutrophils. Here, we studied the effects of mobilization on Toll-like receptor (TLR)-mediated responses. Mobilized granulocytes displayed increased gene and protein expression of TLR2, TLR4, TLR5, and TLR8. Although mobilized granulocytes displayed normal priming of nicotinamide adenine dinucleotide phosphate oxidase activity and a slight increase in adhesion in response to TLR stimulation, these cells produced massive amounts of interleukin-8 (IL-8), in particular to TLR2 and TLR8 stimulation. The increase in IL-8 release occurred despite reduced IL-8 mRNA levels in the donor granulocytes after in vivo G-CSF/dexa treatment, indicating that the enhanced TLR-induced IL-8 production was largely determined by posttranscriptional regulation. In summary, granulocytes mobilized for transfusion purposes show enhanced TLR responsiveness in cytokine production, which is anticipated to be beneficial for the function of these cells on transfusion into patients.
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Post-transcriptional regulation of MEK-1 by polyamines through the RNA-binding protein HuR modulating intestinal epithelial apoptosis. Biochem J 2010; 426:293-306. [PMID: 20001965 DOI: 10.1042/bj20091459] [Citation(s) in RCA: 48] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
MEK-1 [MAPK (mitogen-activated protein kinase) kinase-1] is an important signal transducing enzyme that is implicated in many aspects of cellular functions. In the present paper, we report that cellular polyamines regulate MEK-1 expression at the post-transcriptional level through the RNA-binding protein HuR (Hu-antigen R) in IECs (intestinal epithelial cells). Decreasing the levels of cellular polyamines by inhibiting ODC (ornithine decarboxylase) stabilized MEK-1 mRNA and promoted its translation through enhancement of the interaction between HuR and the 3'-untranslated region of MEK-1 mRNA, whereas increasing polyamine levels by ectopic ODC overexpression destabilized the MEK-1 transcript and repressed its translation by reducing the abundance of HuR-MEK-1 mRNA complex; neither intervention changed MEK-1 gene transcription via its promoter. HuR silencing rendered the MEK-1 mRNA unstable and inhibited its translation, thus preventing increases in MEK-1 mRNA and protein in polyamine-deficient cells. Conversely, HuR overexpression increased MEK-1 mRNA stability and promoted its translation. Inhibition of MEK-1 expression by MEK-1 silencing or HuR silencing prevented the increased resistance of polyamine-deficient cells to apoptosis. Moreover, HuR overexpression did not protect against apoptosis if MEK-1 expression was silenced. These results indicate that polyamines destabilize the MEK-1 mRNA and repress its translation by inhibiting the association between HuR and the MEK-1 transcript. Our findings indicate that MEK-1 is a key effector of the HuR-elicited anti-apoptotic programme in IECs.
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Laloo B, Simon D, Veillat V, Lauzel D, Guyonnet-Duperat V, Moreau-Gaudry F, Sagliocco F, Grosset C. Analysis of post-transcriptional regulations by a functional, integrated, and quantitative method. Mol Cell Proteomics 2010; 8:1777-88. [PMID: 19411282 DOI: 10.1074/mcp.m800503-mcp200] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
In the past 10 years, transcriptome and proteome analyses have provided valuable data on global gene expression and cell functional networks. However, when integrated,these analyses revealed partial correlations between mRNA expression levels and protein abundance thus suggesting that post-transcriptional regulations may be in part responsible for this discrepancy. In the present work, we report the development of a functional, integrated, and quantitative method to measure post-transcriptional regulations that we named FunREG. This method enables (i) quantitative measure of post-transcriptional regulations mediated by selected 3-untranslated regions and exogenous small interfering-RNA or micro-RNAs and (ii) comparison of these regulatory processes in physiologically relevant systems (e.g. cancer versus primary untransformed cells). We applied FunREG to the study of liver cancer, and we demonstrate for the first time the differential regulatory mechanisms controlling gene expression at a post-transcriptional level in normal and tumoral hepatic cells. As an example, translation efficiency mediated by heparin-binding epidermal growth factor 3-untranslated region was increased 3-fold in liver cancer cells compared with normal hepatocytes, whereas stability of an mRNA containing a portion of Cyclin D1 3-untranslated region was increased more than 2-fold in HepG2 cells compared with normal hepatocytes. Consequently we believe that the method presented herein may become an important tool in fundamental and medical research. This approach is convenient and easy to perform, accessible to any investigator, and should be adaptable to a large number of cell type, functional and chemical screens, as well as genome scale analyses. Finally FunREG may represent a helpful tool to reconcile transcriptome and proteome data.
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Affiliation(s)
- Benoît Laloo
- INSERM, U889, Groupe de Recherche pour l'Etude du Foie (GREF), Bordeaux, F-33076 France
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Ishikawa TO, Herschman HR. Tumor formation in a mouse model of colitis-associated colon cancer does not require COX-1 or COX-2 expression. Carcinogenesis 2010; 31:729-36. [PMID: 20061361 DOI: 10.1093/carcin/bgq002] [Citation(s) in RCA: 63] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022] Open
Abstract
Cyclooxygenase-2 (COX-2), a key enzyme of prostanoid biosynthesis, plays an important role in both hereditary and spontaneous colon cancer. Individuals with ulcerative colitis are also at high risk for colorectal cancer. To investigate the role of Cox-2 in colitis-associated colon cancer, we subjected Cox-2 luciferase-knock-in mice and Cox-2-knockout mice to a well-known mouse model of colitis-associated cancer in which animals are treated with a single-azoxymethane (AOM) injection followed by dextran sulfate sodium (DSS) administration. Tumors induced by AOM and DSS expressed significantly higher Cox-2 levels when compared with surrounding areas of colon, as detected both by luciferase reporter gene expression driven from the endogenous Cox-2 promoter and by western blotting of COX-2 protein in Cox-2 luciferase heterozygous knock-in mice. Immunofluorescence revealed that tumor stromal fibroblasts, macrophages and endothelial cells express COX-2 protein. In contrast, little COX-2 expression was observed in myofibroblasts or epithelial cells. Despite a significant elevation of COX-2 expression in AOM/DSS-induced colon tumors in wild-type mice, similar tumors developed in AOM/DSS-treated Cox-2(-/-)- and Cox-1(-/-)-knockout mice. These results indicate that cyclooxygenase-derived prostanoids are not major players in colitis-associated cancer. In contrast, tumor formation induced by multiple injections of AOM (with no DSS-induced colitis) did not occur in Cox-2(-/-)-knockout mice. Our data suggest that the mechanism of colorectal tumor promotion in colitis-associated cancer differs from the mechanism of tumor promotion for hereditary and sporadic colorectal cancer.
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Affiliation(s)
- Tomo-O Ishikawa
- Department of Molecular and Medical Pharmacology, David Geffen School of Medicine, UCLA, Los Angeles, CA, USA
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