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Ye W, Lu J, Yang Z, Yang B, Zhu G, Xue C. Long Non-Coding RNA B3GALT5-AS1 Suppresses Keloid Progression by Regulating the β-Trcp1-Mediated Ubiquitination of HuR. Clin Cosmet Investig Dermatol 2024; 17:967-979. [PMID: 38707608 PMCID: PMC11069380 DOI: 10.2147/ccid.s447772] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/20/2023] [Accepted: 04/21/2024] [Indexed: 05/07/2024]
Abstract
Background lncRNA β‑1,3‑galactosyltransferase 5‑AS1 (B3GALT5-AS1) plays a vital regulatory role in colon and gastric cancers. However, the biological functions and regulatory mechanisms of B3GALT5-AS1 in keloid progression remain unknown. This study aims to investigate the molecular mechanisms in the B3GALT5-AS1-regulated keloid proliferation and invasion. Methods Secondary mining of the lncRNA sequencing data from GSE158395 was conducted to screen differentially expressed lncRNAs between keloid and normal tissues. MTT, cell migration and invasion assays were performed to detect the effects of B3GALT5-AS1 on keloid fibroblasts (KFs) proliferation and metastasis. The extracellular acidification rate (ECAR) and oxygen consumption rate (OCR) were also determined to evaluate glycolysis in KFs. RNA pull-down and RNA-protein immunoprecipitation assays were used to confirm the interaction between B3GALT5-AS1 and Hu-Antigen R (HuR). Further ubiquitination and rescue experiments were performed to elucidate the regulatory relationship between B3GALT5-AS1 and HuR. Results B3GALT5-AS1 was significantly down-regulated in keloid tissues and fibroblasts. B3GALT5-AS1 overexpression significantly inhibited KFs proliferation, glycolysis, invasion, and migration and promoted cell apoptosis, whereas silencing B3GALT5-AS1 inhibited these effects. Moreover, B3GALT5-AS1 binds to HuRand reduces its stability through β-Transducin repeats-containing protein 1 (β-Trcp1)-mediated ubiquitination. Overexpression of HuR reversed the inhibition of B3GALT5-AS1 on cell proliferation, migration, and invasion in KFs, where glycolysis pathway was involved. Conclusion Our findings illustrate that B3GALT5-AS1 has great effect on inhibition of keloid formation, which provides a potential target for keloid therapy.
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Affiliation(s)
- Wei Ye
- Department of Burn Surgery, the First Clinical Medical College of Guangdong Medical University, Huizhou, 516001, People’s Republic of China
| | - Junwen Lu
- Department of Burn Surgery, the First Clinical Medical College of Guangdong Medical University, Huizhou, 516001, People’s Republic of China
| | - Zuxian Yang
- Department of Burn Surgery, Huizhou Municipal Central Hospital, Huizhou, 516001, People’s Republic of China
| | - Ben Yang
- Department of Burn Surgery, Huizhou Municipal Central Hospital, Huizhou, 516001, People’s Republic of China
| | - Guanya Zhu
- Department of Burn Surgery, Huizhou Municipal Central Hospital, Huizhou, 516001, People’s Republic of China
| | - Chunli Xue
- Department of Burn Surgery, Huizhou Municipal Central Hospital, Huizhou, 516001, People’s Republic of China
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Li R, Wang J, Xie Z, Tian X, Hou J, Wang D, Qian H, Shen H, Xu W. CircUSP1 as a novel marker promotes gastric cancer progression via stabilizing HuR to upregulate USP1 and Vimentin. Oncogene 2024; 43:1033-1049. [PMID: 38366146 PMCID: PMC10978489 DOI: 10.1038/s41388-024-02968-8] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/08/2023] [Revised: 02/01/2024] [Accepted: 02/05/2024] [Indexed: 02/18/2024]
Abstract
Circular RNAs (circRNAs) play a crucial role in regulating various tumors. However, their biological functions and mechanisms in gastric cancer (GC) have not been well understood. Here, we discovered a stable cytoplasmic circRNA named circUSP1 (hsa_circ_000613) in GC. CircUSP1 upregulation in GC tissues was correlated with tumor size and differentiation. We observed that circUSP1 promoted GC growth and metastasis. Mechanistically, circUSP1 mainly interacted with the RRM1 domain of an RNA-binding protein (RBP) called HuR, stabilizing its protein level by inhibiting β-TrCP-mediated ubiquitination degradation. The oncogenic properties of HuR mediated promotive effects of circUSP1 in GC progression. Moreover, we identified USP1 and Vimentin as downstream targets of HuR in post-transcriptional regulation, mediating the effects of circUSP1. The parent gene USP1 also enhanced the viability and mobility of GC cells. Additionally, tissue-derived circUSP1 could serve as an independent prognostic factor for GC, while plasma-derived circUSP1 showed promise as a diagnostic biomarker, outperforming conventional markers including serum alpha-fetoprotein (AFP), carcinoembryonic antigen (CEA) and carbohydrate antigen 199 (CA19-9). Our study highlights that circUSP1 promotes GC progression by binding to and stabilizing oncogenic HuR, thereby facilitating the upregulation of USP1 and Vimentin at the post-transcriptional level. These findings suggest that circUSP1 could be a potential therapeutic target and a diagnostic and prognostic biomarker for GC.
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Affiliation(s)
- Rong Li
- Department of Laboratory Medicine, Nanjing Drum Tower Hospital, the Affiliated Hospital of Nanjing University Medical School, Nanjing University, 321 Zhongshan Road, Nanjing, Jiangsu, 210008, China
- Jiangsu Key Laboratory of Medical Science and Laboratory Medicine, School of Medicine, Jiangsu University, 301 Xuefu Road, Zhenjiang, Jiangsu, 212013, China
| | - Junyi Wang
- Centre of Clinical Laboratory, the First Affiliated Hospital of Soochow University, 899 Pinghai Road, Suzhou, Jiangsu, 215006, China
| | - Zhenfan Xie
- Jiangsu Key Laboratory of Medical Science and Laboratory Medicine, School of Medicine, Jiangsu University, 301 Xuefu Road, Zhenjiang, Jiangsu, 212013, China
| | - Xinyu Tian
- Department of Laboratory Medicine, Nanjing Drum Tower Hospital, the Affiliated Hospital of Nanjing University Medical School, Nanjing University, 321 Zhongshan Road, Nanjing, Jiangsu, 210008, China
| | - Jie Hou
- Department of Clinical Laboratory, People's Hospital of Yangzhong City, 235 Yangzi Middle Road, Zhenjiang, Jiangsu, 212200, China
| | - Dongli Wang
- Jiangsu Key Laboratory of Medical Science and Laboratory Medicine, School of Medicine, Jiangsu University, 301 Xuefu Road, Zhenjiang, Jiangsu, 212013, China
| | - Hui Qian
- Jiangsu Key Laboratory of Medical Science and Laboratory Medicine, School of Medicine, Jiangsu University, 301 Xuefu Road, Zhenjiang, Jiangsu, 212013, China
| | - Han Shen
- Department of Laboratory Medicine, Nanjing Drum Tower Hospital, the Affiliated Hospital of Nanjing University Medical School, Nanjing University, 321 Zhongshan Road, Nanjing, Jiangsu, 210008, China.
- Jiangsu Key Laboratory of Medical Science and Laboratory Medicine, School of Medicine, Jiangsu University, 301 Xuefu Road, Zhenjiang, Jiangsu, 212013, China.
| | - Wenrong Xu
- Jiangsu Key Laboratory of Medical Science and Laboratory Medicine, School of Medicine, Jiangsu University, 301 Xuefu Road, Zhenjiang, Jiangsu, 212013, China.
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Goswami B, Nag S, Ray PS. Fates and functions of RNA-binding proteins under stress. WILEY INTERDISCIPLINARY REVIEWS. RNA 2023:e1825. [PMID: 38014833 DOI: 10.1002/wrna.1825] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/11/2023] [Revised: 10/03/2023] [Accepted: 10/30/2023] [Indexed: 11/29/2023]
Abstract
Exposure to stress activates a well-orchestrated set of changes in gene expression programs that allow the cell to cope with and adapt to the stress, or undergo programmed cell death. RNA-protein interactions, mediating all aspects of post-transcriptional regulation of gene expression, play crucial roles in cellular stress responses. RNA-binding proteins (RBPs), which interact with sequence/structural elements in RNAs to control the steps of RNA metabolism, have therefore emerged as central regulators of post-transcriptional responses to stress. Following exposure to a variety of stresses, the dynamic alterations in the RNA-protein interactome enable cells to respond to intracellular or extracellular perturbations by causing changes in mRNA splicing, polyadenylation, stability, translation, and localization. As RBPs play a central role in determining the cellular proteome both qualitatively and quantitatively, it has become increasingly evident that their abundance, availability, and functions are also highly regulated in response to stress. Exposure to stress initiates a series of signaling cascades that converge on post-translational modifications (PTMs) of RBPs, resulting in changes in their subcellular localization, association with stress granules, extracellular export, proteasomal degradation, and RNA-binding activities. These alterations in the fate and function of RBPs directly impact their post-transcriptional regulatory roles in cells under stress. Adopting the ubiquitous RBP HuR as a prototype, three scenarios illustrating the changes in nuclear-cytoplasmic localization, RNA-binding activity, export and degradation of HuR in response to inflammation, genotoxic stress, and heat shock depict the complex and interlinked regulatory mechanisms that control the fate and functions of RBPs under stress. This article is categorized under: RNA Interactions with Proteins and Other Molecules > Protein-RNA Interactions: Functional Implications.
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Affiliation(s)
- Binita Goswami
- Department of Biological Sciences, Indian Institute of Science Education and Research, Mohanpur, West Bengal, India
| | - Sharanya Nag
- Department of Biological Sciences, Indian Institute of Science Education and Research, Mohanpur, West Bengal, India
| | - Partho Sarothi Ray
- Department of Biological Sciences, Indian Institute of Science Education and Research, Mohanpur, West Bengal, India
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4
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Finan JM, Sutton TL, Dixon DA, Brody JR. Targeting the RNA-Binding Protein HuR in Cancer. Cancer Res 2023; 83:3507-3516. [PMID: 37683260 DOI: 10.1158/0008-5472.can-23-0972] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/29/2023] [Revised: 07/12/2023] [Accepted: 09/06/2023] [Indexed: 09/10/2023]
Abstract
The RNA-binding protein human antigen R (HuR) is a well-established regulator of gene expression at the posttranscriptional level. Its dysregulation has been implicated in various human diseases, particularly cancer. In cancer, HuR is considered "active" when it shows increased subcellular localization in the cytoplasm, in addition to its normal nuclear localization. Cytoplasmic HuR plays a crucial role in stabilizing and enhancing the translation of prosurvival mRNAs that are involved in stress responses relevant to cancer progression, such as hypoxia, radiotherapy, and chemotherapy. In general, due to HuR's abundance and function in cancer cells compared with normal cells, it is an appealing target for oncology research. Exploiting the principles underlying HuR's role in tumorigenesis and resistance to stressors, targeting HuR has the potential for synergy with existing and novel oncologic therapies. This review aims to explore HuR's role in homeostasis and cancer pathophysiology, as well as current targeting strategies, which include silencing HuR expression, preventing its translocation and dimerization from the nucleus to the cytoplasm, and inhibiting mRNA binding. Furthermore, this review will discuss recent studies investigating the potential synergy between HuR inhibition and traditional chemotherapeutics.
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Affiliation(s)
- Jennifer M Finan
- Department of Surgery, Oregon Health & Science University, Portland, Oregon
| | - Thomas L Sutton
- Department of Surgery, Oregon Health & Science University, Portland, Oregon
| | - Dan A Dixon
- Department of Molecular Biosciences, University of Kansas, Lawrence, Kansas
| | - Jonathan R Brody
- Department of Surgery, Oregon Health & Science University, Portland, Oregon
- Brenden-Colson Center for Pancreatic Care, Oregon Health & Science University, Portland, Oregon
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Modi N, Chen Y, Dong X, Hu X, Lau GW, Wilson KT, Peek RM, Chen LF. BRD4 Regulates Glycolysis-Dependent Nos2 Expression in Macrophages Upon H pylori Infection. Cell Mol Gastroenterol Hepatol 2023; 17:292-308.e1. [PMID: 37820788 PMCID: PMC10829522 DOI: 10.1016/j.jcmgh.2023.10.001] [Citation(s) in RCA: 6] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/09/2023] [Revised: 10/03/2023] [Accepted: 10/04/2023] [Indexed: 10/13/2023]
Abstract
BACKGROUND & AIMS Metabolic reprogramming is essential for the activation and functions of macrophages, including bacterial killing and cytokine production. Bromodomain-containing protein 4 (BRD4) has emerged as a critical regulator of innate immune response. However, the potential role of BRD4 in the metabolic reprogramming of macrophage activation upon Helicobacter pylori infection remains unclear. METHODS Bone marrow-derived macrophages (BMDMs) from wild-type (WT) and Brd4-myeloid deletion conditional knockout (Brd4-CKO) mice were infected with H pylori. RNA sequencing was performed to evaluate the differential gene expression between WT and Brd4-deficient BMDMs upon infection. An in vivo model of H pylori infection using WT and Brd4-CKO mice was used to confirm the role of BRD4 in innate immune response to infection. RESULTS Depletion of Brd4 in BMDMs showed impaired H pylori-induced glycolysis. In addition, H pylori-induced expression of glycolytic genes, including Slc2a1 and Hk2, was decreased in Brd4-deficient BMDMs. BRD4 was recruited to the promoters of Slc2a1 and Hk2 via hypoxia-inducible factor-1α, facilitating their expression. BRD4-mediated glycolysis stabilized H pylori-induced nitric oxide synthase (Nos2) messenger RNA to produce nitric oxide. The NO-mediated killing of H pylori decreased in Brd4-deficient BMDMs, which was rescued by pyruvate. Furthermore, Brd4-CKO mice infected with H pylori showed reduced gastric inflammation and increased H pylori colonization with reduced inducible NO synthase expression in gastric macrophages. CONCLUSIONS Our study identified BRD4 as a key regulator of hypoxia-inducible factor-1α-dependent glycolysis and macrophage activation. Furthermore, we show a novel regulatory role of BRD4 in innate immunity through glycolysis to stabilize Nos2 messenger RNA for NO production to eliminate H pylori infection.
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Affiliation(s)
- Nikita Modi
- Department of Biochemistry, College of Liberal Arts & Sciences, University of Illinois at Urbana-Champaign, Urbana, Illinois
| | - Yanheng Chen
- Department of Biochemistry, College of Liberal Arts & Sciences, University of Illinois at Urbana-Champaign, Urbana, Illinois
| | - Xingchen Dong
- Department of Biochemistry, College of Liberal Arts & Sciences, University of Illinois at Urbana-Champaign, Urbana, Illinois
| | - Xiangming Hu
- Department of Biochemistry, College of Liberal Arts & Sciences, University of Illinois at Urbana-Champaign, Urbana, Illinois
| | - Gee W Lau
- Department of Pathobiology, College of Veterinary Medicine, University of Illinois at Urbana-Champaign, Urbana, Illinois
| | - Keith T Wilson
- Division of Gastroenterology, Hepatology, and Nutrition, Vanderbilt University Medical Center, Nashville, Tennessee; Veterans Affairs Tennessee Valley Healthcare System, Nashville, Tennessee
| | - Richard M Peek
- Division of Gastroenterology, Hepatology, and Nutrition, Vanderbilt University Medical Center, Nashville, Tennessee
| | - Lin-Feng Chen
- Department of Biochemistry, College of Liberal Arts & Sciences, University of Illinois at Urbana-Champaign, Urbana, Illinois; Carl R. Woese Institute for Genomic Biology, University of Illinois at Urbana-Champaign, Urbana, Illinois.
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6
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Raheja H, George B, Tripathi SK, Saha S, Maiti TK, Das S. Hepatitis C virus non-structural proteins modulate cellular kinases for increased cytoplasmic abundance of host factor HuR and facilitate viral replication. PLoS Pathog 2023; 19:e1011552. [PMID: 37540723 PMCID: PMC10431626 DOI: 10.1371/journal.ppat.1011552] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/05/2023] [Revised: 08/16/2023] [Accepted: 07/11/2023] [Indexed: 08/06/2023] Open
Abstract
Host protein HuR translocation from nucleus to cytoplasm following infection is crucial for the life cycle of several RNA viruses including hepatitis C virus (HCV), a major causative agent of hepatocellular carcinoma. HuR assists the assembly of replication-complex on the viral-3'UTR, and its depletion hampers viral replication. Although cytoplasmic HuR is crucial for HCV replication, little is known about how the virus orchestrates the mobilization of HuR into the cytoplasm from the nucleus. We show that two viral proteins, NS3 and NS5A, act co-ordinately to alter the equilibrium of the nucleo-cytoplasmic movement of HuR. NS3 activates protein kinase C (PKC)-δ, which in-turn phosphorylates HuR on S318 residue, triggering its export to the cytoplasm. NS5A inactivates AMP-activated kinase (AMPK) resulting in diminished nuclear import of HuR through blockade of AMPK-mediated phosphorylation and acetylation of importin-α1. Cytoplasmic retention or entry of HuR can be reversed by an AMPK activator or a PKC-δ inhibitor. Our findings suggest that efforts should be made to develop inhibitors of PKC-δ and activators of AMPK, either separately or in combination, to inhibit HCV infection.
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Affiliation(s)
- Harsha Raheja
- Department of Microbiology and Cell Biology, Indian Institute of Science, Bangalore, India
| | - Biju George
- Department of Microbiology and Cell Biology, Indian Institute of Science, Bangalore, India
| | - Sachin Kumar Tripathi
- Department of Microbiology and Cell Biology, Indian Institute of Science, Bangalore, India
| | | | | | - Saumitra Das
- Department of Microbiology and Cell Biology, Indian Institute of Science, Bangalore, India
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7
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LncGMDS-AS1 promotes the tumorigenesis of colorectal cancer through HuR-STAT3/Wnt axis. Cell Death Dis 2023; 14:165. [PMID: 36849492 PMCID: PMC9970971 DOI: 10.1038/s41419-023-05700-8] [Citation(s) in RCA: 6] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/24/2022] [Revised: 02/15/2023] [Accepted: 02/20/2023] [Indexed: 03/01/2023]
Abstract
Chronic inflammation promotes the tumorigenesis and cell stemness maintenance of colorectal cancer (CRC). However, the bridge role of long noncoding RNA (lncRNA) in linking chronic inflammation to CRC development and progression needs better understanding. Here, we elucidated a novel function of lncRNA GMDS-AS1 in persistently activated signal transducer and transcription activator 3 (STAT3) and Wnt signaling and CRC tumorigenesis. Interleukin-6 (IL-6) and Wnt3a induced lncRNA GMDS-AS1 expression, which was highly expressed in the CRC tissues and plasma of CRC patients. GMDS-AS1 knockdown impaired the survival, proliferation and stem cell-like phenotype acquisition of CRC cells in vitro and in vivo. We performed RNA sequencing (RNA-seq) and mass spectrometry (MS) to probe target proteins and identify their contributions to the downstream signaling pathways of GMDS-AS1. In CRC cells, GMDS-AS1 physically interacted with the RNA-stabilizing protein HuR, thereby protecting the HuR protein from polyubiquitination- and proteasome-dependent degradation. HuR stabilized STAT3 mRNA and upregulated the levels of basal and phosphorylated STAT3 protein, persistently activating STAT3 signaling. Our research revealed that the lncRNA GMDS-AS1 and its direct target HuR constitutively activate STAT3/Wnt signaling and promote CRC tumorigenesis, the GMDS-AS1-HuR-STAT3/Wnt axis is a therapeutic, diagnostic and prognostic target in CRC.
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Fujisaki T, Saito K, Kikuchi T, Kondo E. The prolyl hydroxylase OGFOD1 promotes cancer cell proliferation by regulating the expression of cell cycle regulators. FEBS Lett 2022; 597:1073-1085. [PMID: 36464654 DOI: 10.1002/1873-3468.14547] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/07/2022] [Revised: 11/10/2022] [Accepted: 11/13/2022] [Indexed: 12/12/2022]
Abstract
OGFOD1, a prolyl-hydroxylase, has been reported to translocate from the nucleus to the cytoplasm in response to cellular stress. Here, we demonstrate that OGFOD1 regulates the transcription and post-transcriptional stabilization of cell cycle-related genes. OGFOD1 knockdown in lung cancer cells induced cell cycle arrest through the specific depletion of cyclin-dependent kinase (CDK) 1, CDK2 and cyclin B1 (CCNB1) mRNAs and the nuclear accumulation of p21Cip1 . Analysis of the mRNA dynamics in these cells revealed that CDK1 decreased in a time-dependent manner, reflecting post-transcriptional regulation by OGFOD1 and the RNA-binding protein HuR. In contrast, the depletion of CDK2 and CCNB1 resulted from decreased transcription mediated by OGFOD1. These results indicate that OGFOD1 is required to maintain the function of specific cell cycle regulators during cancer cell proliferation.
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Affiliation(s)
- Toshiya Fujisaki
- Division of Molecular and Cellular Pathology, Niigata University Graduate School of Medical and Dental Sciences, Japan.,Department of Respiratory Medicine and Infectious Diseases, Niigata University Graduate School of Medical and Dental Sciences, Japan
| | - Ken Saito
- Department of Clinical Engineering and Medical Technology, Niigata University of Health and Welfare, Japan
| | - Toshiaki Kikuchi
- Department of Respiratory Medicine and Infectious Diseases, Niigata University Graduate School of Medical and Dental Sciences, Japan
| | - Eisaku Kondo
- Division of Molecular and Cellular Pathology, Niigata University Graduate School of Medical and Dental Sciences, Japan.,Division of Tumor Pathology, Near Infrared Photo-Immunotherapy Research Institute, Kansai Medical University, Osaka, Japan
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Majumder M, Chakraborty P, Mohan S, Mehrotra S, Palanisamy V. HuR as a molecular target for cancer therapeutics and immune-related disorders. Adv Drug Deliv Rev 2022; 188:114442. [PMID: 35817212 DOI: 10.1016/j.addr.2022.114442] [Citation(s) in RCA: 23] [Impact Index Per Article: 11.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/07/2021] [Revised: 04/12/2022] [Accepted: 07/05/2022] [Indexed: 11/19/2022]
Abstract
The control of eukaryotic gene expression occurs at multiple levels, from transcription to messenger RNA processing, transport, localization, turnover, and translation. RNA-binding proteins control gene expression and are involved in different stages of mRNA processing, including splicing, maturation, turnover, and translation. A ubiquitously expressed RBP Human antigen R is engaged in the RNA processes mentioned above but, most importantly, controls mRNA stability and turnover. Dysregulation of HuR is linked to many diseases, including cancer and other immune-related disorders. HuR targets mRNAs containing AU-rich elements at their 3'untranslated region, which encodes proteins involved in cell growth, proliferation, tumor formation, angiogenesis, immune evasion, inflammation, invasion, and metastasis. HuR overexpression has been reported in many tumor types, which led to a poor prognosis for patients. Hence, HuR is considered an appealing drug target for cancer treatment. Therefore, multiple attempts have been made to identify small molecule inhibitors for blocking HuR functions. This article reviews the current prospects of drugs that target HuR in numerous cancer types, their mode of action, and off-target effects. Furthermore, we will summarize drugs that interfered with HuR-RNA interactions and established themselves as novel therapeutics. We will also highlight the significance of HuR overexpression in multiple cancers and discuss its role in immune functions. This review provides evidence of a new era of HuR-targeted small molecules that can be used for cancer therapeutics either as a monotherapy or in combination with other cancer treatment modalities.
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Affiliation(s)
- Mrinmoyee Majumder
- Department of Biochemistry and Molecular Biology, Charleston, SC 29425, USA
| | - Paramita Chakraborty
- Department of Surgery, College of Medicine, Medical University of South Carolina, Charleston, SC 29425, USA
| | - Sarumathi Mohan
- Department of Biochemistry and Molecular Biology, Charleston, SC 29425, USA
| | - Shikhar Mehrotra
- Department of Surgery, College of Medicine, Medical University of South Carolina, Charleston, SC 29425, USA
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Post-Transcriptional Control of mRNA Metabolism and Protein Secretion: The Third Level of Regulation within the NF-κB System. Biomedicines 2022; 10:biomedicines10092108. [PMID: 36140209 PMCID: PMC9495616 DOI: 10.3390/biomedicines10092108] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/29/2022] [Revised: 08/12/2022] [Accepted: 08/21/2022] [Indexed: 11/17/2022] Open
Abstract
The NF-κB system is a key transcriptional pathway that regulates innate and adaptive immunity because it triggers the activation and differentiation processes of lymphocytes and myeloid cells during immune responses. In most instances, binding to cytoplasmic inhibitory IκB proteins sequesters NF-κB into an inactive state, while a plethora of external triggers activate three complex signaling cascades that mediate the release and nuclear translocation of the NF-κB DNA-binding subunits. In addition to these cytosolic steps (level 1 of NF-κB regulation), NF-κB activity is also controlled in the nucleus by signaling events, cofactors and the chromatin environment to precisely determine chromatin recruitment and the specificity and timing of target gene transcription (level 2 of NF-κB regulation). Here, we discuss an additional layer of the NF-κB system that manifests in various steps of post-transcriptional gene expression and protein secretion. This less-studied regulatory level allows reduction of (transcriptional) noise and signal integration and endows time-shifted control of the secretion of inflammatory mediators. Detailed knowledge of these steps is important, as dysregulated post-transcriptional NF-κB signaling circuits are likely to foster chronic inflammation and contribute to the formation and maintenance of a tumor-promoting microenvironment.
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11
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Hu Antigen R (HuR) Protein Structure, Function and Regulation in Hepatobiliary Tumors. Cancers (Basel) 2022; 14:cancers14112666. [PMID: 35681645 PMCID: PMC9179498 DOI: 10.3390/cancers14112666] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/15/2022] [Revised: 05/19/2022] [Accepted: 05/23/2022] [Indexed: 12/10/2022] Open
Abstract
Simple Summary Hepatobiliary tumors are a group of primary malignancies encompassing the liver, the intra- and extra-hepatic biliary tracts, and the gall bladder. Within the liver, hepatocellular carcinoma (HCC) is the most common type of primary cancer, which is, also, representing the third-most recurrent cause of cancer-associated death and the sixth-most prevalent type of tumor worldwide, nowadays. Although less frequent, cholangiocarcinoma (CCA) is, currently, a fatal cancer with limited therapeutic options. Here, we review the regulatory role of Hu antigen R (HuR), a ubiquitous member of the ELAV/Hu family of RNA-binding proteins (RBPs), in the pathogenesis, progression, and treatment of HCC and CCA. Overall, HuR is proposed as a valuable diagnostic and prognostic marker, as well as a therapeutic target in hepatobiliary cancers. Therefore, novel therapeutic approaches that can selectively modulate HuR function appear to be highly attractive for the clinical management of these types of tumors. Abstract Hu antigen R (HuR) is a 36-kDa ubiquitous member of the ELAV/Hu family of RNA-binding proteins (RBPs), which plays an important role as a post-transcriptional regulator of specific RNAs under physiological and pathological conditions, including cancer. Herein, we review HuR protein structure, function, and its regulation, as well as its implications in the pathogenesis, progression, and treatment of hepatobiliary cancers. In particular, we focus on hepatocellular carcinoma (HCC) and cholangiocarcinoma (CCA), tumors where the increased cytoplasmic localization of HuR and activity are proposed, as valuable diagnostic and prognostic markers. An overview of the main regulatory axes involving HuR, which are associated with cell proliferation, invasion, metastasis, apoptosis, and autophagy in HCC, is provided. These include the transcriptional, post-transcriptional, and post-translational modulators of HuR function, in addition to HuR target transcripts. Finally, whereas studies addressing the relevance of targeting HuR in CCA are limited, in the past few years, HuR has emerged as a potential therapeutic target in HCC. In fact, the therapeutic efficacy of some pharmacological inhibitors of HuR has been evaluated, in early experimental models of HCC. We, further, discuss the major findings and future perspectives of therapeutic approaches that specifically block HuR interactions, either with post-translational modifiers or cognate transcripts in hepatobiliary cancers.
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12
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Assoni G, La Pietra V, Digilio R, Ciani C, Licata NV, Micaelli M, Facen E, Tomaszewska W, Cerofolini L, Pérez-Ràfols A, Varela Rey M, Fragai M, Woodhoo A, Marinelli L, Arosio D, Bonomo I, Provenzani A, Seneci P. HuR-targeted agents: An insight into medicinal chemistry, biophysical, computational studies and pharmacological effects on cancer models. Adv Drug Deliv Rev 2022; 181:114088. [PMID: 34942276 DOI: 10.1016/j.addr.2021.114088] [Citation(s) in RCA: 10] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/06/2021] [Revised: 10/07/2021] [Accepted: 12/16/2021] [Indexed: 12/13/2022]
Abstract
The Human antigen R (HuR) protein is an RNA-binding protein, ubiquitously expressed in human tissues, that orchestrates target RNA maturation and processing both in the nucleus and in the cytoplasm. A survey of known modulators of the RNA-HuR interactions is followed by a description of its structure and molecular mechanism of action - RRM domains, interactions with RNA, dimerization, binding modes with naturally occurring and synthetic HuR inhibitors. Then, the review focuses on HuR as a validated molecular target in oncology and briefly describes its role in inflammation. Namely, we show ample evidence for the involvement of HuR in the hallmarks and enabling characteristics of cancer, reporting findings from in vitro and in vivo studies; and we provide abundant experimental proofs of a beneficial role for the inhibition of HuR-mRNA interactions through silencing (CRISPR, siRNA) or pharmacological inhibition (small molecule HuR inhibitors).
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Affiliation(s)
- Giulia Assoni
- Chemistry Department, University of Milan, Via Golgi 19, I-20133 Milan, Italy; Department of Cellular, Computational and Integrative Biology (CIBIO), University of Trento, via Sommarive 9, 38123 Trento, Italy
| | - Valeria La Pietra
- Department of Pharmacy, University of Napoli Federico II, Via D. Montesano 49, 80131 Napoli, Italy
| | - Rosangela Digilio
- Department of Cellular, Computational and Integrative Biology (CIBIO), University of Trento, via Sommarive 9, 38123 Trento, Italy
| | - Caterina Ciani
- Department of Cellular, Computational and Integrative Biology (CIBIO), University of Trento, via Sommarive 9, 38123 Trento, Italy
| | - Nausicaa Valentina Licata
- Department of Cellular, Computational and Integrative Biology (CIBIO), University of Trento, via Sommarive 9, 38123 Trento, Italy
| | - Mariachiara Micaelli
- Department of Cellular, Computational and Integrative Biology (CIBIO), University of Trento, via Sommarive 9, 38123 Trento, Italy
| | - Elisa Facen
- Department of Cellular, Computational and Integrative Biology (CIBIO), University of Trento, via Sommarive 9, 38123 Trento, Italy
| | - Weronika Tomaszewska
- Department of Cellular, Computational and Integrative Biology (CIBIO), University of Trento, via Sommarive 9, 38123 Trento, Italy
| | - Linda Cerofolini
- Magnetic Resonance Center (CERM), University of Florence and Interuniversity Consortium for Magnetic Resonance of Metalloproteins (CIRMMP), Via L. Sacconi 6, 50019 Sesto Fiorentino (FI), Italy
| | - Anna Pérez-Ràfols
- Giotto Biotech S.R.L., Via Madonna del Piano 6, 50019 Sesto Fiorentino (FI), Italy
| | - Marta Varela Rey
- Gene Regulatory Control in Disease Group, Center for Research in Molecular Medicine and Chronic Diseases (CIMUS), Health Research Institute of Santiago de Compostela (IDIS), University of Santiago de Compostela, 15706 Santiago de Compostela, Spain
| | - Marco Fragai
- Magnetic Resonance Center (CERM), University of Florence and Interuniversity Consortium for Magnetic Resonance of Metalloproteins (CIRMMP), Via L. Sacconi 6, 50019 Sesto Fiorentino (FI), Italy
| | - Ashwin Woodhoo
- Gene Regulatory Control in Disease Group, Center for Research in Molecular Medicine and Chronic Diseases (CIMUS), Health Research Institute of Santiago de Compostela (IDIS), University of Santiago de Compostela, 15706 Santiago de Compostela, Spain; Department of Functional Biology, University of Santiago de Compostela, 15782 Santiago de Compostela, Spain; Galician Agency of Innovation (GAIN), Xunta de Galicia, Santiago de Compostela, Spain; Center for Cooperative Research in Biosciences (CIC bioGUNE, Basque Research and Technology Alliance (BRTA), Bizkaia Technology Park, Building 801A, 48160 Derio, Spain; IKERBASQUE, Basque Foundation for Science, Bilbao 48013, Spain
| | - Luciana Marinelli
- Department of Pharmacy, University of Napoli Federico II, Via D. Montesano 49, 80131 Napoli, Italy
| | - Daniela Arosio
- Istituto di Scienze e Tecnologie Chimiche "G. Natta" (SCITEC), National Research Council (CNR), Via C. Golgi 19, I-20133 Milan, Italy
| | - Isabelle Bonomo
- Department of Cellular, Computational and Integrative Biology (CIBIO), University of Trento, via Sommarive 9, 38123 Trento, Italy
| | - Alessandro Provenzani
- Department of Cellular, Computational and Integrative Biology (CIBIO), University of Trento, via Sommarive 9, 38123 Trento, Italy.
| | - Pierfausto Seneci
- Chemistry Department, University of Milan, Via Golgi 19, I-20133 Milan, Italy.
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13
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Guha A, Waris S, Nabors LB, Filippova N, Gorospe M, Kwan T, King PH. The versatile role of HuR in Glioblastoma and its potential as a therapeutic target for a multi-pronged attack. Adv Drug Deliv Rev 2022; 181:114082. [PMID: 34923029 PMCID: PMC8916685 DOI: 10.1016/j.addr.2021.114082] [Citation(s) in RCA: 8] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/15/2021] [Revised: 10/15/2021] [Accepted: 12/12/2021] [Indexed: 02/03/2023]
Abstract
Glioblastoma (GBM) is a malignant and aggressive brain tumor with a median survival of ∼15 months. Resistance to treatment arises from the extensive cellular and molecular heterogeneity in the three major components: glioma tumor cells, glioma stem cells, and tumor-associated microglia and macrophages. Within this triad, there is a complex network of intrinsic and secreted factors that promote classic hallmarks of cancer, including angiogenesis, resistance to cell death, proliferation, and immune evasion. A regulatory node connecting these diverse pathways is at the posttranscriptional level as mRNAs encoding many of the key drivers contain adenine- and uridine rich elements (ARE) in the 3' untranslated region. Human antigen R (HuR) binds to ARE-bearing mRNAs and is a major positive regulator at this level. This review focuses on basic concepts of ARE-mediated RNA regulation and how targeting HuR with small molecule inhibitors represents a plausible strategy for a multi-pronged therapeutic attack on GBM.
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Affiliation(s)
- Abhishek Guha
- Department of Neurology, University of Alabama at Birmingham, Birmingham, AL 35294, United States
| | - Saboora Waris
- Shaheed Zulfiqar Ali Bhutto Medical University, PIMS, G-8, Islamabad, Pakistan
| | - Louis B Nabors
- Department of Neurology, University of Alabama at Birmingham, Birmingham, AL 35294, United States
| | - Natalia Filippova
- Department of Neurology, University of Alabama at Birmingham, Birmingham, AL 35294, United States
| | - Myriam Gorospe
- Laboratory of Genetics and Genomics, National Institute on Aging Intramural Research Program, National Institutes of Health, Baltimore, MD 21224, United States
| | - Thaddaeus Kwan
- Department of Neurology, University of Alabama at Birmingham, Birmingham, AL 35294, United States
| | - Peter H King
- Department of Neurology, University of Alabama at Birmingham, Birmingham, AL 35294, United States; Department of Cell, Developmental, and Integrative Biology, University of Alabama at Birmingham, Birmingham, AL 35294, United States; Birmingham Veterans Affairs Medical Center, Birmingham, AL 35294, United States.
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14
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Ruta V, Pagliarini V, Sette C. Coordination of RNA Processing Regulation by Signal Transduction Pathways. Biomolecules 2021; 11:biom11101475. [PMID: 34680108 PMCID: PMC8533259 DOI: 10.3390/biom11101475] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/13/2021] [Revised: 10/01/2021] [Accepted: 10/05/2021] [Indexed: 02/06/2023] Open
Abstract
Signal transduction pathways transmit the information received from external and internal cues and generate a response that allows the cell to adapt to changes in the surrounding environment. Signaling pathways trigger rapid responses by changing the activity or localization of existing molecules, as well as long-term responses that require the activation of gene expression programs. All steps involved in the regulation of gene expression, from transcription to processing and utilization of new transcripts, are modulated by multiple signal transduction pathways. This review provides a broad overview of the post-translational regulation of factors involved in RNA processing events by signal transduction pathways, with particular focus on the regulation of pre-mRNA splicing, cleavage and polyadenylation. The effects of several post-translational modifications (i.e., sumoylation, ubiquitination, methylation, acetylation and phosphorylation) on the expression, subcellular localization, stability and affinity for RNA and protein partners of many RNA-binding proteins are highlighted. Moreover, examples of how some of the most common signal transduction pathways can modulate biological processes through changes in RNA processing regulation are illustrated. Lastly, we discuss challenges and opportunities of therapeutic approaches that correct RNA processing defects and target signaling molecules.
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Affiliation(s)
- Veronica Ruta
- Department of Neuroscience, Section of Human Anatomy, Catholic University of the Sacred Heart, 00168 Rome, Italy; (V.R.); (V.P.)
- Organoids Facility, IRCCS Fondazione Policlinico Universitario Agostino Gemelli, 00168 Rome, Italy
| | - Vittoria Pagliarini
- Department of Neuroscience, Section of Human Anatomy, Catholic University of the Sacred Heart, 00168 Rome, Italy; (V.R.); (V.P.)
- Organoids Facility, IRCCS Fondazione Policlinico Universitario Agostino Gemelli, 00168 Rome, Italy
| | - Claudio Sette
- Department of Neuroscience, Section of Human Anatomy, Catholic University of the Sacred Heart, 00168 Rome, Italy; (V.R.); (V.P.)
- Laboratory of Neuroembryology, IRCCS Fondazione Santa Lucia, 00143 Rome, Italy
- Correspondence:
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15
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Regulation of Paneth Cell Function by RNA-Binding Proteins and Noncoding RNAs. Cells 2021; 10:cells10082107. [PMID: 34440876 PMCID: PMC8392049 DOI: 10.3390/cells10082107] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/19/2021] [Revised: 08/12/2021] [Accepted: 08/14/2021] [Indexed: 12/20/2022] Open
Abstract
Paneth cells are specialized intestinal epithelial cells that are located at the base of small intestinal crypts and play a vital role in preserving the gut epithelium homeostasis. Paneth cells act as a safeguard from bacterial translocation across the epithelium and constitute the niche for intestinal stem cells in the small intestine by providing multiple niche signals. Recently, Paneth cells have become the focal point of investigations defining the mechanisms underlying the epithelium-microbiome interactions and pathogenesis of chronic gut mucosal inflammation and bacterial infection. Function of Paneth cells is tightly regulated by numerous factors at different levels, while Paneth cell defects have been widely documented in various gut mucosal diseases in humans. The post-transcription events, specific change in mRNA stability and translation by RNA-binding proteins (RBPs) and noncoding RNAs (ncRNAs) are implicated in many aspects of gut mucosal physiology by modulating Paneth cell function. Deregulation of RBPs and ncRNAs and subsequent Paneth cell defects are identified as crucial elements of gut mucosal pathologies. Here, we overview the posttranscriptional regulation of Paneth cells by RBPs and ncRNAs, with a particular focus on the increasing evidence of RBP HuR and long ncRNA H19 in this process. We also discuss the involvement of Paneth cell dysfunction in altered susceptibility of the intestinal epithelium to chronic inflammation and bacterial infection following disrupted expression of HuR and H19.
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16
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Chen J, Wu Y, Luo X, Jin D, Zhou W, Ju Z, Wang D, Meng Q, Wang H, Fu X, Xu J, Song Z. Circular RNA circRHOBTB3 represses metastasis by regulating the HuR-mediated mRNA stability of PTBP1 in colorectal cancer. Am J Cancer Res 2021; 11:7507-7526. [PMID: 34158864 PMCID: PMC8210600 DOI: 10.7150/thno.59546] [Citation(s) in RCA: 89] [Impact Index Per Article: 29.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/18/2021] [Accepted: 05/21/2021] [Indexed: 01/17/2023] Open
Abstract
Background: Tumor metastasis of colorectal cancer (CRC) is the main cause of death in most patients and the major difficulty in comprehensive CRC treatment. Circular RNAs (circRNAs) affect many biological functions in solid tumors. However, their mechanisms in CRC metastasis remain unclear. Methods: RNA sequencing (RNA-seq) and quantitative real-time PCR were performed to screen differentially expressed circRNAs between CRC tissues and adjacent normal tissues. CCK-8, cell migration and wound healing assays were performed to determine the functions of circRHOBTB3 in cell proliferation and metastasis. RNA pulldown and RNA immunoprecipitation assays were performed to verify the interaction between circRHOBTB3 and the HuR (ELAVL1) protein. Further RNA-seq and rescue experiments were applied to search for the downstream target. We also conducted a mouse xenograft model to elucidate the effect of circRHOBTB3 on cancer metastasis in vivo. Results: We identified circRHOBTB3 which is markedly downregulated in CRC tissues and cell lines. Furthermore, lower circRHOBTB3 levels were significantly associated with advanced clinical stages and greater risk of metastases. Overexpression of circRHOBTB3 suppresses tumor metastasis in CRC cells. Mechanistically, circRHOBTB3 binds to HuR, which is a ubiquitously expressed and functional RNA-binding protein (RBP) in CRC development, and promotes β-Trcp1-mediated ubiquitination of HuR. Normally, HuR binds to the 3'UTR of target mRNAs to facilitate their stabilization, whereas the interaction between circRHOBTB3 and HuR degrades HuR to reduce the expression level of the downstream target PTBP1. Furthermore, overexpressed circRHOBTB3 suppresses lung metastases in vivo, and this effect can be partly reversed by PTBP1 overexpression. In addition, the transcription of circRHOBTB3 can be improved by both FUS and ADARB2 in CRC cells. Conclusions: Our findings indicate that circRHOBTB3 exerts suppressive effects on CRC aggressiveness through the HuR/PTBP1 axis.
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17
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Velázquez-Cruz A, Baños-Jaime B, Díaz-Quintana A, De la Rosa MA, Díaz-Moreno I. Post-translational Control of RNA-Binding Proteins and Disease-Related Dysregulation. Front Mol Biosci 2021; 8:658852. [PMID: 33987205 PMCID: PMC8111222 DOI: 10.3389/fmolb.2021.658852] [Citation(s) in RCA: 36] [Impact Index Per Article: 12.0] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/26/2021] [Accepted: 03/22/2021] [Indexed: 12/20/2022] Open
Abstract
Cell signaling mechanisms modulate gene expression in response to internal and external stimuli. Cellular adaptation requires a precise and coordinated regulation of the transcription and translation processes. The post-transcriptional control of mRNA metabolism is mediated by the so-called RNA-binding proteins (RBPs), which assemble with specific transcripts forming messenger ribonucleoprotein particles of highly dynamic composition. RBPs constitute a class of trans-acting regulatory proteins with affinity for certain consensus elements present in mRNA molecules. However, these regulators are subjected to post-translational modifications (PTMs) that constantly adjust their activity to maintain cell homeostasis. PTMs can dramatically change the subcellular localization, the binding affinity for RNA and protein partners, and the turnover rate of RBPs. Moreover, the ability of many RBPs to undergo phase transition and/or their recruitment to previously formed membrane-less organelles, such as stress granules, is also regulated by specific PTMs. Interestingly, the dysregulation of PTMs in RBPs has been associated with the pathophysiology of many different diseases. Abnormal PTM patterns can lead to the distortion of the physiological role of RBPs due to mislocalization, loss or gain of function, and/or accelerated or disrupted degradation. This Mini Review offers a broad overview of the post-translational regulation of selected RBPs and the involvement of their dysregulation in neurodegenerative disorders, cancer and other pathologies.
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Affiliation(s)
- Alejandro Velázquez-Cruz
- Instituto de Investigaciones Químicas, Centro de Investigaciones Científicas Isla de la Cartuja, Universidad de Sevilla, Consejo Superior de Investigaciones Científicas, Seville, Spain
| | - Blanca Baños-Jaime
- Instituto de Investigaciones Químicas, Centro de Investigaciones Científicas Isla de la Cartuja, Universidad de Sevilla, Consejo Superior de Investigaciones Científicas, Seville, Spain
| | - Antonio Díaz-Quintana
- Instituto de Investigaciones Químicas, Centro de Investigaciones Científicas Isla de la Cartuja, Universidad de Sevilla, Consejo Superior de Investigaciones Científicas, Seville, Spain
| | - Miguel A De la Rosa
- Instituto de Investigaciones Químicas, Centro de Investigaciones Científicas Isla de la Cartuja, Universidad de Sevilla, Consejo Superior de Investigaciones Científicas, Seville, Spain
| | - Irene Díaz-Moreno
- Instituto de Investigaciones Químicas, Centro de Investigaciones Científicas Isla de la Cartuja, Universidad de Sevilla, Consejo Superior de Investigaciones Científicas, Seville, Spain
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18
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Antonia RJ, Hagan RS, Baldwin AS. Expanding the View of IKK: New Substrates and New Biology. Trends Cell Biol 2021; 31:166-178. [PMID: 33422358 DOI: 10.1016/j.tcb.2020.12.003] [Citation(s) in RCA: 50] [Impact Index Per Article: 16.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/04/2020] [Revised: 11/16/2020] [Accepted: 12/07/2020] [Indexed: 01/07/2023]
Abstract
The inhibitor of kappa B kinase (IKK) family consists of IKKα, IKKβ, and the IKK-related kinases TBK1 and IKKε. These kinases are considered master regulators of inflammation and innate immunity via their control of the transcription factors NF-κB, IRF3, and IRF7. Novel phosphorylated substrates have been attributed to these kinases, a subset of which is not directly related to either inflammation or innate immunity. These findings have greatly expanded the perspectives on the biological activities of these kinases. In this review we highlight some of the novel substrates for this kinase family and discuss the biological implications of these phosphorylation events.
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Affiliation(s)
- Ricardo J Antonia
- Department of Surgery, Division of Surgical Oncology, and The Hellen Diller Comprehensive Cancer Center, The University of California San Francisco, San Francisco, CA, USA
| | - Robert S Hagan
- Division of Pulmonary Diseases and Critical Care Medicine, Department of Medicine, University of North Carolina, Chapel Hill, NC 27599, USA; Marsico Lung Institute, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599, USA
| | - Albert S Baldwin
- Lineberger Comprehensive Cancer Center, University of North Carolina at Chapel Hill, Chapel Hill, NC, USA.
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19
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Kumar R, Poria DK, Ray PS. RNA-binding proteins La and HuR cooperatively modulate translation repression of PDCD4 mRNA. J Biol Chem 2021; 296:100154. [PMID: 33288677 PMCID: PMC7949077 DOI: 10.1074/jbc.ra120.014894] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/18/2020] [Revised: 12/03/2020] [Accepted: 12/06/2020] [Indexed: 12/28/2022] Open
Abstract
Posttranscriptional regulation of gene expression plays a critical role in controlling the inflammatory response. An uncontrolled inflammatory response results in chronic inflammation, often leading to tumorigenesis. Programmed cell death 4 (PDCD4) is a proinflammatory tumor-suppressor gene which helps to prevent the transition from chronic inflammation to cancer. PDCD4 mRNA translation is regulated by an interplay between the oncogenic microRNA miR-21 and the RNA-binding protein (RBP) human antigen R (HuR) in response to lipopolysaccharide stimulation, but the role of other regulatory factors remains unknown. Here, we report that the RBP lupus antigen (La) interacts with the 3'-untranslated region of PDCD4 mRNA and prevents miR-21-mediated translation repression. While lipopolysaccharide causes nuclear-cytoplasmic translocation of HuR, it enhances cellular La expression. Remarkably, La and HuR were found to bind cooperatively to the PDCD4 mRNA and mitigate miR-21-mediated translation repression. The cooperative action of La and HuR reduced cell proliferation and enhanced apoptosis, reversing the pro-oncogenic function of miR-21. Together, these observations demonstrate a cooperative interplay between two RBPs, triggered differentially by the same stimulus, which exerts a synergistic effect on PDCD4 expression and thereby helps maintain a balance between inflammation and tumorigenesis.
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Affiliation(s)
- Ravi Kumar
- Department of Biological Sciences, Indian Institute of Science Education and Research, Kolkata, Mohanpur, Nadia, West Bengal, India
| | - Dipak Kumar Poria
- Department of Biological Sciences, Indian Institute of Science Education and Research, Kolkata, Mohanpur, Nadia, West Bengal, India
| | - Partho Sarothi Ray
- Department of Biological Sciences, Indian Institute of Science Education and Research, Kolkata, Mohanpur, Nadia, West Bengal, India.
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20
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Long noncoding RNA ASB16-AS1 inhibits adrenocortical carcinoma cell growth by promoting ubiquitination of RNA-binding protein HuR. Cell Death Dis 2020; 11:995. [PMID: 33219221 PMCID: PMC7679391 DOI: 10.1038/s41419-020-03205-2] [Citation(s) in RCA: 16] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/28/2020] [Revised: 11/02/2020] [Accepted: 11/04/2020] [Indexed: 12/14/2022]
Abstract
Adrenocortical carcinoma is one of the aggressive malignancies and it originates from the cortex of adrenal gland. Dysregulation of long non-coding RNA plays important roles in the development of adrenocortical carcinoma. Here, we found that lncRNA ASB16-AS1 was down-regulated in adrenocortical carcinoma and ASB16-AS1 functions as tumor suppressor in vitro and in vivo. We then found that IGF1R and CDK6 are regulated by ASB16-AS1 in adrenocortical carcinoma cells by transcriptome RNA sequencing. ASB16-AS1 associates with RNA-binding protein HuR (ELAVL1) as revealed by RNA pull-down following mass spectrometry. Also, ASB16-AS1 inhibits HuR expression post-translationally by promoting its ubiquitination. ASB16-AS1 regulates IGF1R and CDK6 mRNA expression through RNA-binding protein HuR. We then found that inhibition of ASB16-AS1 attenuates the binding of ubiquitin E3 ligase BTRC to HuR and subsequently inhibits HuR protein unbiquitination and degradation. BTRC knock-down could reverse the effect of AB16-AS1 on HuR, CDK6, and IGF1R levels. Collectively, these results demonstrate that ASB16-AS1 regulates adrenocortical carcinoma cell proliferation and tackling the level of ASB16-AS1 may be developed to treat adrenocortical carcinoma.
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21
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Bi Y, Cui D, Xiong X, Zhao Y. The characteristics and roles of β-TrCP1/2 in carcinogenesis. FEBS J 2020; 288:3351-3374. [PMID: 33021036 DOI: 10.1111/febs.15585] [Citation(s) in RCA: 27] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/07/2020] [Revised: 09/02/2020] [Accepted: 10/01/2020] [Indexed: 12/11/2022]
Abstract
β-transducin repeat-containing protein (β-TrCP), one of the well-characterized F-box proteins, acts as a substrate receptor and constitutes an active SCFβ-TrCP E3 ligase with a scaffold protein CUL1, a RING protein RBX1, and an adaptor protein SKP1. β-TrCP plays a critical role in the regulation of various physiological and pathological processes, including signal transduction, cell cycle progression, cell migration, DNA damage response, and tumorigenesis, by governing burgeoning amounts of key regulators for ubiquitination and proteasomal degradation. Given that a variety of β-TrCP substrates are well-known oncoproteins and tumor suppressors, and dysregulation of β-TrCP is frequently identified in human cancers, β-TrCP plays a vital role in carcinogenesis. In this review, we first briefly introduce the characteristics of β-TrCP1, β-TrCP2, and SCFβ-TrCP ubiquitin ligase, and then discuss SCFβ-TrCP ubiquitin ligase regulated biological processes by targeting its substrates for degradation. Moreover, we summarize the regulation of β-TrCP1 and β-TrCP2 at multiple layers and further discuss the various roles of β-TrCP1 and β-TrCP2 in human cancer, functioning as either an oncoprotein or a tumor suppressor in a manner dependent of cellular context. Finally, we provide novel insights for future perspectives on the potential of targeting β-TrCP1 and β-TrCP2 for cancer therapy.
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Affiliation(s)
- Yanli Bi
- Key Laboratory of Combined Multi-Organ Transplantation, Ministry of Public Health, the First Affiliated Hospital, Zhejiang University School of Medicine, Hangzhou, China.,Institute of Translational Medicine, Zhejiang University School of Medicine, Hangzhou, China
| | - Danrui Cui
- Key Laboratory of Combined Multi-Organ Transplantation, Ministry of Public Health, the First Affiliated Hospital, Zhejiang University School of Medicine, Hangzhou, China.,Institute of Translational Medicine, Zhejiang University School of Medicine, Hangzhou, China
| | - Xiufang Xiong
- Institute of Translational Medicine, Zhejiang University School of Medicine, Hangzhou, China.,Cancer Institute of the Second Affiliated Hospital, Zhejiang University School of Medicine, Hangzhou, China
| | - Yongchao Zhao
- Key Laboratory of Combined Multi-Organ Transplantation, Ministry of Public Health, the First Affiliated Hospital, Zhejiang University School of Medicine, Hangzhou, China.,Institute of Translational Medicine, Zhejiang University School of Medicine, Hangzhou, China
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22
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Schultz CW, Preet R, Dhir T, Dixon DA, Brody JR. Understanding and targeting the disease-related RNA binding protein human antigen R (HuR). WILEY INTERDISCIPLINARY REVIEWS-RNA 2020; 11:e1581. [PMID: 31970930 DOI: 10.1002/wrna.1581] [Citation(s) in RCA: 118] [Impact Index Per Article: 29.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/16/2019] [Revised: 12/02/2019] [Accepted: 12/07/2019] [Indexed: 02/06/2023]
Abstract
Altered gene expression is a characteristic feature of many disease states such as tumorigenesis, and in most cancers, it facilitates cancer cell survival and adaptation. Alterations in global gene expression are strongly impacted by post-transcriptional gene regulation. The RNA binding protein (RBP) HuR (ELAVL1) is an established regulator of post-transcriptional gene regulation and is overexpressed in most human cancers. In many cancerous settings, HuR is not only overexpressed, but it is "overactive" as denoted by increased subcellular localization within the cytoplasm. This dysregulation of HuR expression and cytoplasmic localization allows HuR to stabilize and increase the translation of various prosurvival messenger RNA (mRNAs) involved in the pathogenesis of numerous cancers and various diseases. Based on almost 20 years of work, HuR is now recognized as a therapeutic target. Herein, we will review the role HuR plays in the pathophysiology of different diseases and ongoing therapeutic strategies to target HuR. We will focus on three ongoing-targeted strategies: (1) inhibiting HuR's translocation from the nucleus to the cytoplasm; (2) inhibiting the ability of HuR to bind target RNA; and (3) silencing HuR expression levels. In an oncologic setting, HuR has been demonstrated to be critical for a cancer cell's ability to survive a variety of cancer relevant stressors (including drugs and elements of the tumor microenvironment) and targeting this protein has been shown to sensitize cancer cells further to insult. We strongly believe that targeting HuR could be a powerful therapeutic target to treat different diseases, particularly cancer, in the near future. This article is categorized under: RNA in Disease and Development > RNA in Disease NRA Turnover and Surveillance > Regulation of RNA Stability Translation > Translation Regulation.
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Affiliation(s)
- Christopher W Schultz
- Department of Surgery, Jefferson Pancreas, Biliary and Related Cancer Center, Thomas Jefferson University, Philadelphia, Pennsylvania
| | - Ranjan Preet
- Department of Molecular Biosciences, University of Kansas, Lawrence, Kansas
| | - Teena Dhir
- Department of Surgery, Jefferson Pancreas, Biliary and Related Cancer Center, Thomas Jefferson University, Philadelphia, Pennsylvania
| | - Dan A Dixon
- Department of Molecular Biosciences, University of Kansas, Lawrence, Kansas
| | - Jonathan R Brody
- Department of Surgery, Jefferson Pancreas, Biliary and Related Cancer Center, Thomas Jefferson University, Philadelphia, Pennsylvania
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23
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Lan Y, Xiao X, He Z, Luo Y, Wu C, Li L, Song X. Long noncoding RNA OCC-1 suppresses cell growth through destabilizing HuR protein in colorectal cancer. Nucleic Acids Res 2019; 46:5809-5821. [PMID: 29931370 PMCID: PMC6009600 DOI: 10.1093/nar/gky214] [Citation(s) in RCA: 140] [Impact Index Per Article: 28.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/23/2017] [Accepted: 03/13/2018] [Indexed: 02/05/2023] Open
Abstract
Overexpressed in colon carcinoma-1 (OCC-1) is one of the earliest annotated long noncoding RNAs (lncRNAs) in colorectal cancer (CRC); however, its function remains largely unknown. Here, we revealed that OCC-1 plays a tumor suppressive role in CRC. OCC-1 knockdown by RNA interference promotes cell growth both in vitro and in vivo, which is largely due to its ability to inhibit G0 to G1 and G1 to S phase cell cycle transitions. In addition, overexpression of OCC-1 can suppress cell growth in OCC-1 knockdown cells. OCC-1 exerts its function by binding to and destabilizing HuR (ELAVL1), a cancer-associated RNA binding protein (RBP) which can bind to and stabilize thousands of mRNAs. OCC-1 enhances the binding of ubiquitin E3 ligase β-TrCP1 to HuR and renders HuR susceptible to ubiquitination and degradation, thereby reducing the levels of HuR and its target mRNAs, including the mRNAs directly associated with cancer cell growth. These findings reveal that lncRNA OCC-1 can regulate the levels of a large number of mRNAs at post-transcriptional level through modulating RBP HuR stability.
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Affiliation(s)
- Yang Lan
- Center for Functional Genomics and Bioinformatics, Key Laboratory of Bio-Resource and Eco-Environment of Ministry of Education, College of Life Sciences, Sichuan University, Chengdu 610065, Sichuan, P.R. China
| | - Xuewei Xiao
- Center for Functional Genomics and Bioinformatics, Key Laboratory of Bio-Resource and Eco-Environment of Ministry of Education, College of Life Sciences, Sichuan University, Chengdu 610065, Sichuan, P.R. China
| | - Zhengchi He
- Center for Functional Genomics and Bioinformatics, Key Laboratory of Bio-Resource and Eco-Environment of Ministry of Education, College of Life Sciences, Sichuan University, Chengdu 610065, Sichuan, P.R. China
| | - Yu Luo
- Center for Functional Genomics and Bioinformatics, Key Laboratory of Bio-Resource and Eco-Environment of Ministry of Education, College of Life Sciences, Sichuan University, Chengdu 610065, Sichuan, P.R. China
| | - Chuanfang Wu
- Center for Functional Genomics and Bioinformatics, Key Laboratory of Bio-Resource and Eco-Environment of Ministry of Education, College of Life Sciences, Sichuan University, Chengdu 610065, Sichuan, P.R. China
| | - Ling Li
- Center for Functional Genomics and Bioinformatics, Key Laboratory of Bio-Resource and Eco-Environment of Ministry of Education, College of Life Sciences, Sichuan University, Chengdu 610065, Sichuan, P.R. China
| | - Xu Song
- Center for Functional Genomics and Bioinformatics, Key Laboratory of Bio-Resource and Eco-Environment of Ministry of Education, College of Life Sciences, Sichuan University, Chengdu 610065, Sichuan, P.R. China.,State Key Laboratory of Biotherapy, West China Hospital, Sichuan University, Chengdu 610041, Sichuan, P.R. China
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24
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Human antigen R protein modulates vascular endothelial growth factor expression in human corneal epithelial cells under hypoxia. J Formos Med Assoc 2019; 119:359-366. [PMID: 31262614 DOI: 10.1016/j.jfma.2019.06.006] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/11/2019] [Revised: 05/20/2019] [Accepted: 06/14/2019] [Indexed: 01/23/2023] Open
Abstract
PURPOSE Corneal avascularity is critical for corneal transparency; therefore, a tailored process has been presumed to minimize corneal neovascularization (NV). In most cell types, the transcription of vascular endothelial growth factor (VEGF) is up-regulated, and the stability of VEGF mRNA is sustained by human antigen R (HuR) during hypoxia; however, whether such response applies to corneal epithelial cells is unclear. METHODS Human corneal epithelial cells (HCECs) and MCF-7 cells that serves as the control were incubated under 0.5% oxygen, and the levels of VEGF and HuR were examined time-dependently. The alteration of HuR was also examined in vivo using the closed-eye contact lens-induced corneal neovascularization rabbit model and immunohistochemistry. Additionally, the expression of HuR was modulated by transfection of plasmids encoding HuR or siRNA targeting HuR to validate the role of HuR in VEGF expression. RESULTS We found that, unlike in control cells, the level of VEGF was not up-regulated, and the HuR expression was declined in HCECs following hypoxia. The HuR immunostaining intensities were decreased in corneal epithelial cells of rabbits wearing contact lenses. In addition, HuR overexpression restored the ability of HCECs to up-regulate VEGF under hypoxia; however, knockdown of HuR suppressed hypoxia-induced VEGF in control cells but did not further decrease VEGF in HCECs. These findings suggest that HCECs may modulate HuR to suppress hypoxia-mediated up-regulation of VEGF. CONCLUSION Our study revealed a distinct regulation of VEGF via HuR in HCECs following hypoxia, which likely contributes to minimizing corneal NV and/or maintenance of corneal avascularity.
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25
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Guha A, Ahuja D, Das Mandal S, Parasar B, Deyasi K, Roy D, Sharma V, Willard B, Ghosh A, Ray PS. Integrated Regulation of HuR by Translation Repression and Protein Degradation Determines Pulsatile Expression of p53 Under DNA Damage. iScience 2019; 15:342-359. [PMID: 31103853 PMCID: PMC6548907 DOI: 10.1016/j.isci.2019.05.002] [Citation(s) in RCA: 25] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/25/2018] [Revised: 12/20/2018] [Accepted: 05/01/2019] [Indexed: 12/21/2022] Open
Abstract
Expression of tumor suppressor p53 is regulated at multiple levels, disruption of which often leads to cancer. We have adopted an approach combining computational systems modeling with experimental validation to elucidate the translation regulatory network that controls p53 expression post DNA damage. The RNA-binding protein HuR activates p53 mRNA translation in response to UVC-induced DNA damage in breast carcinoma cells. p53 and HuR levels show pulsatile change post UV irradiation. The computed model fitted with the observed pulse of p53 and HuR only when hypothetical regulators of synthesis and degradation of HuR were incorporated. miR-125b, a UV-responsive microRNA, was found to represses the translation of HuR mRNA. Furthermore, UV irradiation triggered proteasomal degradation of HuR mediated by an E3-ubiquitin ligase tripartite motif-containing 21 (TRIM21). The integrated action of miR-125b and TRIM21 constitutes an intricate control system that regulates pulsatile expression of HuR and p53 and determines cell viability in response to DNA damage.
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Affiliation(s)
- Abhishek Guha
- Department of Biological Sciences, Indian Institute of Science Education and Research Kolkata, Mohanpur 741246, West Bengal, India
| | - Deepika Ahuja
- Department of Biological Sciences, Indian Institute of Science Education and Research Kolkata, Mohanpur 741246, West Bengal, India
| | - Sukhen Das Mandal
- Department of Biological Sciences, Indian Institute of Science Education and Research Kolkata, Mohanpur 741246, West Bengal, India
| | - Bibudha Parasar
- Department of Chemical Sciences, Indian Institute of Science Education and Research Kolkata, Mohanpur 741246, West Bengal, India
| | - Krishanu Deyasi
- Department of Mathematics and Statistics, Indian Institute of Science Education and Research Kolkata, Mohanpur 741246, West Bengal, India
| | - Debadrita Roy
- Department of Biological Sciences, Indian Institute of Science Education and Research Kolkata, Mohanpur 741246, West Bengal, India
| | - Vasundhara Sharma
- Department of Biological Sciences, Indian Institute of Science Education and Research Kolkata, Mohanpur 741246, West Bengal, India
| | - Belinda Willard
- Proteomics and Metabolomics Core, Lerner Research Institute, Cleveland Clinic, 9500 Euclid Avenue, Cleveland, OH 44195, USA
| | - Anandamohan Ghosh
- Department of Physical Sciences, Indian Institute of Science Education and Research Kolkata, Mohanpur 741246, West Bengal, India
| | - Partho Sarothi Ray
- Department of Biological Sciences, Indian Institute of Science Education and Research Kolkata, Mohanpur 741246, West Bengal, India.
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26
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Ma Y, Cui D, Xiong X, Inuzuka H, Wei W, Sun Y, North BJ, Zhao Y. SCFβ-TrCP ubiquitinates CHK1 in an AMPK-dependent manner in response to glucose deprivation. Mol Oncol 2018; 13:307-321. [PMID: 30428154 PMCID: PMC6360357 DOI: 10.1002/1878-0261.12403] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/20/2018] [Revised: 09/17/2018] [Accepted: 10/15/2018] [Indexed: 12/15/2022] Open
Abstract
The ATR/CHK1 pathway is a key effector of cellular response to DNA damage and therefore is a critical regulator of genomic stability. While the ATR/CHK1 pathway is often inactivated by mutations, CHK1 itself is rarely mutated in human cancers. Thus, cellular levels of CHK1 likely play a key role in the maintenance of genomic stability and preventing tumorigenesis. Glucose deprivation is observed in many solid tumors due to high glycolytic rates of cancer cells and insufficient vascularization, yet cancer cells have devised mechanisms to survive in conditions of low glucose. Although CHK1 degradation through the ubiquitin-proteasome pathway following glucose deprivation has been previously reported, the detailed molecular mechanisms remain elusive. Here, we show that CHK1 is ubiquitinated and degraded upon glucose deprivation by the Skp1-Cullin-F-box (β-TrCP) E3 ubiquitin ligase. Specifically, CHK1 contains a β-TrCP recognizable degron domain, which is phosphorylated by AMPK in response to glucose deprivation, allowing for β-TrCP to recognize CHK1 for subsequent ubiquitination and degradation. Our results provide a novel mechanism by which glucose metabolism regulates a DNA damage effector, and imply that glucose deprivation, which is often found in solid tumor microenvironments, may enhance mutagenesis, clonal expansion, and tumor progression by triggering CHK1 degradation.
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Affiliation(s)
- Ying Ma
- Key Laboratory of Combined Multi-Organ Transplantation, Ministry of Public Health, First Affiliated Hospital, Zhejiang University School of Medicine, Hangzhou, China.,Institute of Translational Medicine, Zhejiang University School of Medicine, Hangzhou, China.,Department of Pathology, Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, MA, USA
| | - Danrui Cui
- Key Laboratory of Combined Multi-Organ Transplantation, Ministry of Public Health, First Affiliated Hospital, Zhejiang University School of Medicine, Hangzhou, China.,Institute of Translational Medicine, Zhejiang University School of Medicine, Hangzhou, China
| | - Xiufang Xiong
- Institute of Translational Medicine, Zhejiang University School of Medicine, Hangzhou, China
| | - Hiroyuki Inuzuka
- Department of Pathology, Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, MA, USA.,Center for Advanced Stem Cell and Regenerative Research, Tohoku University Graduate School of Dentistry, Sendai, Japan
| | - Wenyi Wei
- Department of Pathology, Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, MA, USA
| | - Yi Sun
- Institute of Translational Medicine, Zhejiang University School of Medicine, Hangzhou, China.,Division of Radiation and Cancer Biology, Department of Radiation Oncology, University of Michigan, Ann Arbor, MI, USA
| | - Brian J North
- Department of Pathology, Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, MA, USA
| | - Yongchao Zhao
- Key Laboratory of Combined Multi-Organ Transplantation, Ministry of Public Health, First Affiliated Hospital, Zhejiang University School of Medicine, Hangzhou, China.,Institute of Translational Medicine, Zhejiang University School of Medicine, Hangzhou, China
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27
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Masuda K, Kuwano Y. Diverse roles of RNA-binding proteins in cancer traits and their implications in gastrointestinal cancers. WILEY INTERDISCIPLINARY REVIEWS-RNA 2018; 10:e1520. [PMID: 30479000 DOI: 10.1002/wrna.1520] [Citation(s) in RCA: 41] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/05/2018] [Revised: 10/31/2018] [Accepted: 11/01/2018] [Indexed: 02/06/2023]
Abstract
Gene expression patterns in cancer cells are strongly influenced by posttranscriptional mechanisms. RNA-binding proteins (RBPs) play key roles in posttranscriptional gene regulation; they can interact with target mRNAs in a sequence- and structure-dependent manner, and determine cellular behavior by manipulating the processing of these mRNAs. Numerous RBPs are aberrantly deregulated in many human cancers and hence, affect the functioning of mRNAs that encode proteins, implicated in carcinogenesis. Here, we summarize the key roles of RBPs in posttranscriptional gene regulation, describe RBPs disrupted in cancer, and lastly focus on RBPs that are responsible for implementing cancer traits in the digestive tract. These evidences may reveal a potential link between changes in expression/function of RBPs and malignant transformation, and a framework for new insights and potential therapeutic applications. This article is categorized under: RNA in Disease and Development > RNA in Disease RNA Interactions with Proteins and Other Molecules > Protein-RNA Interactions: Functional Implications.
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Affiliation(s)
- Kiyoshi Masuda
- Kawasaki Medical School at Kurashiki-City, Okayama, Japan
| | - Yuki Kuwano
- Department of Pathophysiology, Institute of Biomedical Sciences, Tokushima University Graduate School at Tokushima-City, Tokushima, Japan
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28
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α4 Coordinates Small Intestinal Epithelium Homeostasis by Regulating Stability of HuR. Mol Cell Biol 2018; 38:MCB.00631-17. [PMID: 29555726 DOI: 10.1128/mcb.00631-17] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/08/2017] [Accepted: 03/08/2018] [Indexed: 02/06/2023] Open
Abstract
The mammalian intestinal epithelium is a rapidly self-renewing tissue in the body, and its homeostasis depends on a dynamic balance among proliferation, migration, apoptosis, and differentiation of intestinal epithelial cells (IECs). The protein phosphatase 2A (PP2A)-associated protein α4 controls the activity and specificity of serine/threonine phosphatases and is thus implicated in many cellular processes. Here, using a genetic approach, we investigated the mechanisms whereby α4 controls the homeostasis of the intestinal epithelium. In mice with ablated α4, the small intestinal mucosa exhibited crypt hyperplasia, villus shrinkage, defective differentiation of Paneth cells, and reduced IEC migration along the crypt-villus axis. The α4-deficient intestinal epithelium also displayed decreased expression of different intercellular junction proteins and abnormal epithelial permeability. In addition, α4 deficiency decreased the levels of the RNA-binding protein HuR in the mucosal tissue. In cultured IECs, ectopic overexpression of HuR in α4-deficient cells rescued the production of these intercellular junction proteins and restored the epithelial barrier function to a nearly normal level. Mechanistically, α4 silencing destabilized HuR through a process involving HuR phosphorylation by IκB kinase α, leading to ubiquitin-mediated proteolysis of HuR. These findings indicate that the critical impact of α4 upon the barrier function and homeostasis of the intestinal epithelium depends largely on its ability to regulate the stability of HuR.
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29
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Sun XF, Sun XH, Cheng SF, Wang JJ, Feng YN, Zhao Y, Yin S, Hou ZM, Shen W, Zhang XF. Interaction of the transforming growth factor-β and Notch signaling pathways in the regulation of granulosa cell proliferation. Reprod Fertil Dev 2018; 28:1873-1881. [PMID: 26036783 DOI: 10.1071/rd14398] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/21/2014] [Accepted: 05/06/2015] [Indexed: 12/20/2022] Open
Abstract
The Notch and transforming growth factor (TGF)-β signalling pathways play an important role in granulosa cell proliferation. However, the mechanisms underlying the cross-talk between these two signalling pathways are unknown. Herein we demonstrated a functional synergism between Notch and TGF-β signalling in the regulation of preantral granulosa cell (PAGC) proliferation. Activation of TGF-β signalling increased hairy/enhancer-of-split related with YRPW motif 2 gene (Hey2) expression (one of the target genes of the Notch pathway) in PAGCs, and suppression of TGF-β signalling by Smad3 knockdown reduced Hey2 expression. Inhibition of the proliferation of PAGCs by N-[N-(3,5-difluorophenacetyl)-l-alanyl]-S-phenylglycine t-butylester (DAPT), an inhibitor of Notch signalling, was rescued by both the addition of ActA and overexpression of Smad3, indicating an interaction between the TGF-β and Notch signalling pathways. Co-immunoprecipitation (CoIP) and chromatin immunoprecipitation (ChIP) assays were performed to identify the point of interaction between the two signalling pathways. CoIP showed direct protein-protein interaction between Smad3 and Notch2 intracellular domain (NICD2), whereas ChIP showed that Smad3 could be recruited to the promoter regions of Notch target genes as a transcription factor. Therefore, the findings of the present study support the idea that nuclear Smad3 protein can integrate with NICD2 to form a complex that acts as a transcription factor to bind specific DNA motifs in Notch target genes, such as Hey1 and Hey2, and thus participates in the transcriptional regulation of Notch target genes, as well as regulation of the proliferation of PAGCs.
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Affiliation(s)
- Xiao-Feng Sun
- Key Laboratory of Animal Reproduction and Germplasm Enhancement in Universities of Shandong, Qingdao 266109, China
| | - Xing-Hong Sun
- Key Laboratory of Animal Reproduction and Germplasm Enhancement in Universities of Shandong, Qingdao 266109, China
| | - Shun-Feng Cheng
- Key Laboratory of Animal Reproduction and Germplasm Enhancement in Universities of Shandong, Qingdao 266109, China
| | - Jun-Jie Wang
- Key Laboratory of Animal Reproduction and Germplasm Enhancement in Universities of Shandong, Qingdao 266109, China
| | - Yan-Ni Feng
- Key Laboratory of Animal Reproduction and Germplasm Enhancement in Universities of Shandong, Qingdao 266109, China
| | - Yong Zhao
- Key Laboratory of Animal Reproduction and Germplasm Enhancement in Universities of Shandong, Qingdao 266109, China
| | - Shen Yin
- Key Laboratory of Animal Reproduction and Germplasm Enhancement in Universities of Shandong, Qingdao 266109, China
| | - Zhu-Mei Hou
- Key Laboratory of Animal Reproduction and Germplasm Enhancement in Universities of Shandong, Qingdao 266109, China
| | - Wei Shen
- Key Laboratory of Animal Reproduction and Germplasm Enhancement in Universities of Shandong, Qingdao 266109, China
| | - Xi-Feng Zhang
- College of Biological and Pharmaceutical Engineering, Wuhan Polytechnic University, Wuhan 430023, China
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30
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Shang J, Zhao Z. Emerging role of HuR in inflammatory response in kidney diseases. Acta Biochim Biophys Sin (Shanghai) 2017; 49:753-763. [PMID: 28910975 DOI: 10.1093/abbs/gmx071] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/05/2017] [Accepted: 06/21/2017] [Indexed: 12/14/2022] Open
Abstract
Human antigen R (HuR) is a member of the embryonic lethal abnormal vision (ELAV) family which can bind to the A/U rich elements in 3' un-translated region of mRNA and regulate mRNA splicing, transportation, and stability. Unlike other members of the ELAV family, HuR is ubiquitously expressed. Early studies mainly focused on HuR function in malignant diseases. As researches proceed, more and more proofs demonstrate its relationship with inflammation. Since most kidney diseases involve pathological changes of inflammation, HuR is now suggested to play a pivotal role in glomerular nephropathy, tubular ischemia-reperfusion damage, renal fibrosis and even renal tumors. By regulating the mRNAs of target genes, HuR is causally linked to the onset and progression of kidney diseases. Reports on this topic are steadily increasing, however, the detailed function and mechanism of action of HuR are still not well understood. The aim of this review article is to summarize the present understanding of the role of HuR in inflammation in kidney diseases, and we anticipate that future research will ultimately elucidate the therapeutic value of this novel target.
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Affiliation(s)
- Jin Shang
- Nephrology Hospital, The First Affiliated Hospital of Zhengzhou University, Zhengzhou 450052, China
| | - Zhanzheng Zhao
- Nephrology Hospital, The First Affiliated Hospital of Zhengzhou University, Zhengzhou 450052, China
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31
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Filippova N, Yang X, Ananthan S, Sorochinsky A, Hackney JR, Gentry Z, Bae S, King P, Nabors LB. Hu antigen R (HuR) multimerization contributes to glioma disease progression. J Biol Chem 2017; 292:16999-17010. [PMID: 28790173 DOI: 10.1074/jbc.m117.797878] [Citation(s) in RCA: 32] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/22/2017] [Revised: 07/27/2017] [Indexed: 12/21/2022] Open
Abstract
Among primary brain cancers, gliomas are the most deadly and most refractory to current treatment modalities. Previous reports overwhelmingly support the role of the RNA-binding protein Hu antigen R (HuR) as a positive regulator of glioma disease progression. HuR expression is consistently elevated in tumor tissues, and a cytoplasmic localization appears essential for HuR-dependent oncogenic transformation. Here, we report HuR aggregation (multimerization) in glioma and the analysis of this tumor-specific HuR protein multimerization in clinical brain tumor samples. Using a split luciferase assay, a bioluminescence resonance energy transfer technique, and site-directed mutagenesis, we examined the domains involved in HuR multimerization. Results obtained with the combination of the split HuR luciferase assay with the bioluminescence resonance energy transfer technique suggested that multiple (at least three) HuR molecules come together during HuR multimerization in glioma cells. Using these data, we developed a model of HuR multimerization in glioma cells. We also demonstrate that exposing glioma cells to the HuR inhibitor tanshinone group compound 15,16-dihydrotanshinone-I or to the newly identified compound 5 disrupts HuR multimerization modules and reduces tumor cell survival and proliferation. In summary, our findings provide new insights into HuR multimerization in glioma and highlight possible pharmacological approaches for targeting HuR domains involved in cancer cell-specific multimerization.
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Affiliation(s)
| | | | | | | | | | | | - Sejong Bae
- Medicine, School of Medicine, University of Alabama, Birmingham, Alabama 35294
| | - Peter King
- From the Departments of Neurology.,Birmingham Veterans Affairs Medical Center, Birmingham, Alabama 35294
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32
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Grammatikakis I, Abdelmohsen K, Gorospe M. Posttranslational control of HuR function. WILEY INTERDISCIPLINARY REVIEWS-RNA 2016; 8. [PMID: 27307117 DOI: 10.1002/wrna.1372] [Citation(s) in RCA: 164] [Impact Index Per Article: 20.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/12/2016] [Revised: 05/18/2016] [Accepted: 05/19/2016] [Indexed: 12/28/2022]
Abstract
The RNA-binding protein HuR (human antigen R) associates with numerous transcripts, coding and noncoding, and controls their splicing, localization, stability, and translation. Through its regulation of target transcripts, HuR has been implicated in cellular events including proliferation, senescence, differentiation, apoptosis, and the stress and immune responses. In turn, HuR influences processes such as cancer and inflammation. HuR function is primarily regulated through posttranslational modifications that alter its subcellular localization and its ability to bind target RNAs; such modifications include phosphorylation, methylation, ubiquitination, NEDDylation, and proteolytic cleavage. In this review, we describe the modifications that impact upon HuR function on gene expression programs and disease states. WIREs RNA 2017, 8:e1372. doi: 10.1002/wrna.1372 For further resources related to this article, please visit the WIREs website.
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Affiliation(s)
- Ioannis Grammatikakis
- Laboratory of Genetics, National Institute on Aging, National Institutes of Health, Baltimore, MD, USA
| | - Kotb Abdelmohsen
- Laboratory of Genetics, National Institute on Aging, National Institutes of Health, Baltimore, MD, USA
| | - Myriam Gorospe
- Laboratory of Genetics, National Institute on Aging, National Institutes of Health, Baltimore, MD, USA
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33
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Prislei S, Martinelli E, Zannoni GF, Petrillo M, Filippetti F, Mariani M, Mozzetti S, Raspaglio G, Scambia G, Ferlini C. Role and prognostic significance of the epithelial-mesenchymal transition factor ZEB2 in ovarian cancer. Oncotarget 2016; 6:18966-79. [PMID: 26136338 PMCID: PMC4662468 DOI: 10.18632/oncotarget.3943] [Citation(s) in RCA: 54] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/09/2014] [Accepted: 05/05/2015] [Indexed: 12/12/2022] Open
Abstract
ZEB2 is a key factor in epithelial-mesenchymal transition (EMT), a program controlling cell migration in embryonic development and adult tissue homeostasis. We demonstrated a role of ZEB2 in migration and anchorage-independent cell growth in ovarian cancer, as shown by ZEB2 silencing. We found that the RNA-binding protein HuR bound the 3′UTR of ZEB2 mRNA, acting as a positive regulator of ZEB2 protein expression. In Hey ovarian cell line, HuR silencing decreased ZEB2 and ZEB1 nuclear expression and impaired migration. In hypoglycemic conditions ZEB2 expression decreased, along with ZEB1, vimentin and cytoplasmic HuR, and a reduced cellular migration ability was observed. Analysis of ZEB2 and HuR expression in ovarian cancers revealed that nuclear ZEB2 is localized in tumor leading edge and co-localizes with cytoplasmic HuR. In a series of 143 ovarian cancer patients high expression of ZEB2 mRNA significantly correlated with a poor prognosis in term of both overall survival and progression- free survival. Moreover, at immunohistochemical evaluation, we found that prognostic significance of ZEB2 protein relies on its nuclear expression and co-localization with cytoplasmic HuR. In conclusion our findings indicated that nuclear ZEB2 may enhance progression of EMT transition and acquisition of an aggressive phenotype in ovarian cancer.
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Affiliation(s)
- Silvia Prislei
- Department of Obstetrics and Gynecology, Catholic University of the Sacred Heart, Rome, Italy
| | - Enrica Martinelli
- Department of Obstetrics and Gynecology, Catholic University of the Sacred Heart, Rome, Italy
| | - Gian Franco Zannoni
- Department of Obstetrics and Gynecology, Catholic University of the Sacred Heart, Rome, Italy.,Department of Pathology, Catholic University of the Sacred Heart, Rome, Italy
| | - Marco Petrillo
- Department of Obstetrics and Gynecology, Catholic University of the Sacred Heart, Rome, Italy
| | - Flavia Filippetti
- Department of Obstetrics and Gynecology, Catholic University of the Sacred Heart, Rome, Italy
| | - Marisa Mariani
- Reproductive Tumor Biology Research, Biomedical Lab, Department of Obstetrics and Gynecology, Danbury Hospital, Danbury, CT, USA
| | - Simona Mozzetti
- Department of Obstetrics and Gynecology, Catholic University of the Sacred Heart, Rome, Italy
| | - Giuseppina Raspaglio
- Department of Obstetrics and Gynecology, Catholic University of the Sacred Heart, Rome, Italy
| | - Giovanni Scambia
- Department of Obstetrics and Gynecology, Catholic University of the Sacred Heart, Rome, Italy
| | - Cristiano Ferlini
- Department of Obstetrics and Gynecology, Catholic University of the Sacred Heart, Rome, Italy.,Reproductive Tumor Biology Research, Biomedical Lab, Department of Obstetrics and Gynecology, Danbury Hospital, Danbury, CT, USA
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Lucchesi C, Sheikh MS, Huang Y. Negative regulation of RNA-binding protein HuR by tumor-suppressor ECRG2. Oncogene 2015; 35:2565-73. [PMID: 26434587 DOI: 10.1038/onc.2015.339] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/27/2015] [Revised: 07/23/2015] [Accepted: 08/04/2015] [Indexed: 01/10/2023]
Abstract
Esophageal cancer-related gene 2 (ECRG2) is a newer tumor suppressor whose function in the regulation of cell growth and apoptosis remains to be elucidated. Here we show that ECRG2 expression was upregulated in response to DNA damage, and increased ECRG2 expression induced growth suppression in cancer cells but not in non-cancerous epithelial cells. ECRG2-mediated growth suppression was associated with activation of caspases and marked reduction in the levels of apoptosis inhibitor, X chromosome-linked inhibitor of apoptosis protein (XIAP). ECRG2, via RNA-binding protein human antigen R (HuR), regulated XIAP mRNA stability and expression. Furthermore, ECRG2 increased HuR ubiquitination and degradation but was unable to modulate the non-ubiquitinable mutant form of HuR. We also identified missense and frame-shift ECRG2 mutations in various human malignancies and noted that, unlike wild-type ECRG2, one cancer-derived ECRG2 mutant harboring glutamic acid instead of valine at position 30 (V30E) failed to induce cell death and activation of caspases. This naturally occurring V30E mutant also did not suppress XIAP and HuR. Importantly, the V30E mutant overexpressing cancer cells acquired resistance against multiple anticancer drugs, thus suggesting that ECRG2 mutations appear to have an important role in the acquisition of anticancer drug resistance in a subset of human malignancies.
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Affiliation(s)
- C Lucchesi
- Department of Pharmacology, State University of New York, Upstate Medical University, Syracuse, NY, USA
| | - M S Sheikh
- Department of Pharmacology, State University of New York, Upstate Medical University, Syracuse, NY, USA
| | - Y Huang
- Department of Pharmacology, State University of New York, Upstate Medical University, Syracuse, NY, USA
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35
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Brennan-Laun SE, Ezelle HJ, Li XL, Hassel BA. RNase-L control of cellular mRNAs: roles in biologic functions and mechanisms of substrate targeting. J Interferon Cytokine Res 2015; 34:275-88. [PMID: 24697205 DOI: 10.1089/jir.2013.0147] [Citation(s) in RCA: 39] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/12/2023] Open
Abstract
RNase-L is a mediator of type 1 interferon-induced antiviral activity that has diverse and critical cellular roles, including the regulation of cell proliferation, differentiation, senescence and apoptosis, tumorigenesis, and the control of the innate immune response. Although RNase-L was originally shown to mediate the endonucleolytic cleavage of both viral and ribosomal RNAs in response to infection, more recent evidence indicates that RNase-L also functions in the regulation of cellular mRNAs as an important mechanism by which it exerts its diverse biological functions. Despite this growing body of work, many questions remain regarding the roles of mRNAs as RNase-L substrates. This review will survey known and putative mRNA substrates of RNase-L, propose mechanisms by which it may selectively cleave these transcripts, and postulate future clinical applications.
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Affiliation(s)
- Sarah E Brennan-Laun
- 1 Marlene and Stewart Greenebaum Cancer Center, University of Maryland School of Medicine , Baltimore, Maryland
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36
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Low TY, Peng M, Magliozzi R, Mohammed S, Guardavaccaro D, Heck AJR. A systems-wide screen identifies substrates of the SCFβTrCP ubiquitin ligase. Sci Signal 2014; 7:rs8. [PMID: 25515538 DOI: 10.1126/scisignal.2005882] [Citation(s) in RCA: 40] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
Cellular proteins are degraded by the ubiquitin-proteasome system (UPS) in a precise and timely fashion. Such precision is conferred by the high substrate specificity of ubiquitin ligases. Identification of substrates of ubiquitin ligases is crucial not only to unravel the molecular mechanisms by which the UPS controls protein degradation but also for drug discovery purposes because many established UPS substrates are implicated in disease. We developed a combined bioinformatics and affinity purification-mass spectrometry (AP-MS) workflow for the system-wide identification of substrates of SCF(βTrCP), a member of the SCF family of ubiquitin ligases. These ubiquitin ligases are characterized by a multisubunit architecture typically consisting of the invariable subunits Rbx1, Cul1, and Skp1 and one of 69 F-box proteins. The F-box protein of this member of the family is βTrCP. SCF(βTrCP) binds, through the WD40 repeats of βTrCP, to the DpSGXX(X)pS diphosphorylated motif in its substrates. We recovered 27 previously reported SCF(βTrCP) substrates, of which 22 were verified by two independent statistical protocols, thereby confirming the reliability of this approach. In addition to known substrates, we identified 221 proteins that contained the DpSGXX(X)pS motif and also interacted specifically with the WD40 repeats of βTrCP. Thus, with SCF(βTrCP), as the example, we showed that integration of structural information, AP-MS, and degron motif mining constitutes an effective method to screen for substrates of ubiquitin ligases.
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Affiliation(s)
- Teck Yew Low
- Biomolecular Mass Spectrometry and Proteomics, Bijvoet Center for Biomolecular Research and Utrecht Institute for Pharmaceutical Sciences, Utrecht University, Padualaan 8, 3584 CH Utrecht, Netherlands. Netherlands Proteomics Center, Padualaan 8, 3584 CH Utrecht, Netherlands
| | - Mao Peng
- Biomolecular Mass Spectrometry and Proteomics, Bijvoet Center for Biomolecular Research and Utrecht Institute for Pharmaceutical Sciences, Utrecht University, Padualaan 8, 3584 CH Utrecht, Netherlands. Netherlands Proteomics Center, Padualaan 8, 3584 CH Utrecht, Netherlands
| | - Roberto Magliozzi
- Hubrecht Institute-KNAW (Royal Netherlands Academy of Arts and Sciences) and University Medical Center Utrecht, Uppsalalaan 8, 3584 CT Utrecht, Netherlands
| | - Shabaz Mohammed
- Biomolecular Mass Spectrometry and Proteomics, Bijvoet Center for Biomolecular Research and Utrecht Institute for Pharmaceutical Sciences, Utrecht University, Padualaan 8, 3584 CH Utrecht, Netherlands. Netherlands Proteomics Center, Padualaan 8, 3584 CH Utrecht, Netherlands
| | - Daniele Guardavaccaro
- Hubrecht Institute-KNAW (Royal Netherlands Academy of Arts and Sciences) and University Medical Center Utrecht, Uppsalalaan 8, 3584 CT Utrecht, Netherlands
| | - Albert J R Heck
- Biomolecular Mass Spectrometry and Proteomics, Bijvoet Center for Biomolecular Research and Utrecht Institute for Pharmaceutical Sciences, Utrecht University, Padualaan 8, 3584 CH Utrecht, Netherlands. Netherlands Proteomics Center, Padualaan 8, 3584 CH Utrecht, Netherlands.
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Substrate trapping proteomics reveals targets of the βTrCP2/FBXW11 ubiquitin ligase. Mol Cell Biol 2014; 35:167-81. [PMID: 25332235 DOI: 10.1128/mcb.00857-14] [Citation(s) in RCA: 42] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022] Open
Abstract
Defining the full complement of substrates for each ubiquitin ligase remains an important challenge. Improvements in mass spectrometry instrumentation and computation and in protein biochemistry methods have resulted in several new methods for ubiquitin ligase substrate identification. Here we used the parallel adapter capture (PAC) proteomics approach to study βTrCP2/FBXW11, a substrate adaptor for the SKP1-CUL1-F-box (SCF) E3 ubiquitin ligase complex. The processivity of the ubiquitylation reaction necessitates transient physical interactions between FBXW11 and its substrates, thus making biochemical purification of FBXW11-bound substrates difficult. Using the PAC-based approach, we inhibited the proteasome to "trap" ubiquitylated substrates on the SCF(FBXW11) E3 complex. Comparative mass spectrometry analysis of immunopurified FBXW11 protein complexes before and after proteasome inhibition revealed 21 known and 23 putatively novel substrates. In focused studies, we found that SCF(FBXW11) bound, polyubiquitylated, and destabilized RAPGEF2, a guanine nucleotide exchange factor that activates the small GTPase RAP1. High RAPGEF2 protein levels promoted cell-cell fusion and, consequently, multinucleation. Surprisingly, this occurred independently of the guanine nucleotide exchange factor (GEF) catalytic activity and of the presence of RAP1. Our data establish new functions for RAPGEF2 that may contribute to aneuploidy in cancer. More broadly, this report supports the continued use of substrate trapping proteomics to comprehensively define targets for E3 ubiquitin ligases. All proteomic data are available via ProteomeXchange with identifier PXD001062.
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Govindaraju S, Lee BS. Krüppel -like factor 8 is a stress-responsive transcription factor that regulates expression of HuR. Cell Physiol Biochem 2014; 34:519-32. [PMID: 25116351 DOI: 10.1159/000363019] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 06/12/2014] [Indexed: 12/26/2022] Open
Abstract
BACKGROUND/AIMS HuR is an RNA-binding protein that regulates the post-transcriptional life of thousands of cellular mRNAs and promotes cell survival. HuR is expressed as two mRNA transcripts that are differentially regulated by cell stress. The goal of this study is to define factors that promote transcription of the longer alternate form. METHODS Effects of transcription factors on HuR expression were determined by inhibition or overexpression of these factors followed by competitive RT-PCR, gel mobility shift, and chromatin immunoprecipitation. Transcription factor expression patterns were identified through competitive RT-PCR and Western analysis. Stress responses were assayed in thapsigargin-treated proximal tubule cells and in ischemic rat kidney. RESULTS A previously described NF-κB site and a newly identified Sp/KLF factor binding site were shown to be important for transcription of the long HuR mRNA. KLF8, but not Sp1, was shown to bind this site and increase HuR mRNA levels. Cellular stress in cultured or native proximal tubule cells resulted in a rapid decrease of KLF8 levels that paralleled those of the long HuR mRNA variant. CONCLUSIONS These results demonstrate that KLF8 can participate in regulating expression of alternate forms of HuR mRNA along with NF-κB and other factors, depending on cellular contexts.
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Affiliation(s)
- Suman Govindaraju
- Department of Physiology and Cell Biology, The Ohio State University College of Medicine and Ohio State Biochemistry Program, Columbus, Ohio, USA
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Søreide K, Sund M. Epidemiological-molecular evidence of metabolic reprogramming on proliferation, autophagy and cell signaling in pancreas cancer. Cancer Lett 2014; 356:281-8. [PMID: 24704294 DOI: 10.1016/j.canlet.2014.03.028] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/04/2014] [Revised: 02/28/2014] [Accepted: 03/25/2014] [Indexed: 02/07/2023]
Abstract
Pancreatic cancer remains one of the deadliest human cancers with little progress made in survival over the past decades, and 5-year survival usually below 5%. Despite this dismal scenario, progresses have been made in understanding of the underlying tumor biology through among other definition of precursor lesions, delineation of molecular pathways, and advances in genome-wide technology. Further, exploring the relationship between epidemiological risk factors involving metabolic features to that of an altered cancer metabolism may provide the foundation for new therapies. Here we explore how nutrients and caloric intake may influence the KRAS-driven ductal carcinogenesis through mediators of metabolic stress, including autophagy in presence of TP53, advanced glycation end products (AGE) and the receptors (RAGE) and ligands (HMGB1), as well as glutamine pathways, among others. Effective understanding the cancer metabolism mechanisms in pancreatic cancer may propose new ways of prevention and treatment.
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Affiliation(s)
- Kjetil Søreide
- Department of Gastrointestinal Surgery, Stavanger University Hospital, Stavanger, Norway; Department of Clinical Medicine, University of Bergen, Bergen, Norway.
| | - Malin Sund
- Department of Surgical and Perioperative Sciences, Surgery, Umeå University, Umeå, Sweden
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Govindaraju S, Lee BS. Adaptive and maladaptive expression of the mRNA regulatory protein HuR. World J Biol Chem 2013; 4:111-118. [PMID: 24340134 PMCID: PMC3856306 DOI: 10.4331/wjbc.v4.i4.111] [Citation(s) in RCA: 33] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/28/2013] [Revised: 08/31/2013] [Accepted: 11/05/2013] [Indexed: 02/05/2023] Open
Abstract
The RNA-binding proteins involved in regulation of mRNA post-transcriptional processing and translation control the fates of thousands of mRNA transcripts and basic cellular processes. The best studied of these, HuR, is well characterized as a mediator of mRNA stability and translation, and more recently, as a factor in nuclear functions such as pre-mRNA splicing. Due to HuR’s role in regulating thousands of mRNA transcripts, including those for other RNA-binding proteins, HuR can act as a master regulator of cell survival and proliferation. HuR itself is subject to multiple post-translational modifications including regulation of its nucleocytoplasmic distribution. However, the mechanisms that govern HuR levels in the cell have only recently begun to be defined. These mechanisms are critical to cell health, as it has become clear in recent years that aberrant expression of HuR can lead alternately to decreased cell viability or to promotion of pathological proliferation and invasiveness. HuR is expressed as alternate mRNAs that vary in their untranslated regions, leading to differences in transcript stability and translatability. Multiple transcription factors and modulators of mRNA stability that regulate HuR mRNA expression have been identified. In addition, translation of HuR is regulated by numerous microRNAs, several of which have been demonstrated to have anti-tumor properties due to their suppression of HuR expression. This review summarizes the current state of knowledge of the factors that regulate HuR expression, along with the circumstances under which these factors contribute to cancer and inflammation.
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Thapar R, Denmon AP. Signaling pathways that control mRNA turnover. Cell Signal 2013; 25:1699-710. [PMID: 23602935 PMCID: PMC3703460 DOI: 10.1016/j.cellsig.2013.03.026] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/17/2013] [Accepted: 03/29/2013] [Indexed: 02/06/2023]
Abstract
Cells regulate their genomes mainly at the level of transcription and at the level of mRNA decay. While regulation at the level of transcription is clearly important, the regulation of mRNA turnover by signaling networks is essential for a rapid response to external stimuli. Signaling pathways result in posttranslational modification of RNA binding proteins by phosphorylation, ubiquitination, methylation, acetylation etc. These modifications are important for rapid remodeling of dynamic ribonucleoprotein complexes and triggering mRNA decay. Understanding how these posttranslational modifications alter gene expression is therefore a fundamental question in biology. In this review we highlight recent findings on how signaling pathways and cell cycle checkpoints involving phosphorylation, ubiquitination, and arginine methylation affect mRNA turnover.
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Affiliation(s)
- Roopa Thapar
- Hauptman-Woodward Medical Research Institute, 700 Ellicott Street, Buffalo, NY 14203, USA.
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Burkhart RA, Pineda DM, Chand SN, Romeo C, Londin ER, Karoly ED, Cozzitorto JA, Rigoutsos I, Yeo CJ, Brody JR, Winter JM. HuR is a post-transcriptional regulator of core metabolic enzymes in pancreatic cancer. RNA Biol 2013; 10:1312-23. [PMID: 23807417 DOI: 10.4161/rna.25274] [Citation(s) in RCA: 42] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022] Open
Abstract
Cancer cell metabolism differs from normal cells, yet the regulatory mechanisms responsible for these differences are incompletely understood, particularly in response to acute changes in the tumor microenvironment. HuR, an RNA-binding protein, acts under acute stress to regulate core signaling pathways in cancer through post-transcriptional regulation of mRNA targets. We demonstrate that HuR regulates the metabolic phenotype in pancreatic cancer cells and is critical for survival under acute glucose deprivation. Using three pancreatic cancer cell line models, HuR-proficient cells demonstrated superior survival under glucose deprivation when compared with isogenic cells with siRNA-silencing of HuR expression (HuR-deficient cells). We found that HuR-proficient cells utilized less glucose, but produced greater lactate, as compared with HuR-deficient cells. Acute glucose deprivation was found to act as a potent stimulus for HuR translocation from the nucleus to the cytoplasm, where HuR stabilizes its mRNA targets. We performed a gene expression array on ribonucleoprotein-immunoprecipitated mRNAs bound to HuR and identified 11 novel HuR target transcripts that encode enzymes central to glucose metabolism. Three (GPI, PRPS2 and IDH1) were selected for validation studies, and confirmed as bona fide HuR targets. These findings establish HuR as a critical regulator of pancreatic cancer cell metabolism and survival under acute glucose deprivation. Further explorations into HuR's role in cancer cell metabolism should uncover novel therapeutic targets that are critical for cancer cell survival in a metabolically compromised tumor microenvironment.
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Affiliation(s)
- Richard A Burkhart
- Department of Surgery; Jefferson Pancreas, Biliary and Related Cancer Center; Philadelphia, PA USA
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Shtyren MI. [Venous pathomorphology in occlusive lesions of the arteries of the lower extremities]. Carcinogenesis 1990; 34:2694-705. [PMID: 2386438 DOI: 10.1093/carcin/bgt251] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023] Open
Abstract
The study was performed of 80 low extremities amputated because of gangrene related to atherosclerosis (28 cases) or obliterating thromboangiitis (52 cases). Two types of vein histological changes were established: 1) changes similar to those in arteries as in the thromboangiitis 2) adaptive-compensatory changes resulting from haemodynamics disturbances as in atherosclerosis. A great number of arteriovenous anastomoses, vein wall hypertrophy with the change of their calibre were observed. Hypertrophy of the muscle layer and dilatation of the vein lumen are found in cases with long duration of the process. The differences in vein morphology in the above diseases, apart from etiology, are due to the fact that in obliterating thromboangiitis the process starts in the peripheral vessels while in atherosclerosis it begins in large arteries and the vein alterations develop at late stages. The vein alterations may serve as the differential diagnostic index in these diseases.
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