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Jaiswal AK, Thaxton ML, Scherer GM, Sorrentino JP, Garg NK, Rao DS. Small molecule inhibition of RNA binding proteins in haematologic cancer. RNA Biol 2024; 21:1-14. [PMID: 38329136 PMCID: PMC10857685 DOI: 10.1080/15476286.2024.2303558] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 01/05/2024] [Indexed: 02/09/2024] Open
Abstract
In recent years, advances in biomedicine have revealed an important role for post-transcriptional mechanisms of gene expression regulation in pathologic conditions. In cancer in general and leukaemia specifically, RNA binding proteins have emerged as important regulator of RNA homoeostasis that are often dysregulated in the disease state. Having established the importance of these pathogenetic mechanisms, there have been a number of efforts to target RNA binding proteins using oligonucleotide-based strategies, as well as with small organic molecules. The field is at an exciting inflection point with the convergence of biomedical knowledge, small molecule screening strategies and improved chemical methods for synthesis and construction of sophisticated small molecules. Here, we review the mechanisms of post-transcriptional gene regulation, specifically in leukaemia, current small-molecule based efforts to target RNA binding proteins, and future prospects.
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Affiliation(s)
- Amit K. Jaiswal
- Department of Pathology and Laboratory Medicine, University of California, Los Angeles, CA, USA
| | - Michelle L. Thaxton
- Department of Pathology and Laboratory Medicine, University of California, Los Angeles, CA, USA
| | - Georgia M. Scherer
- Department of Chemistry and Biochemistry, University of California, Los Angeles, CA, USA
| | - Jacob P. Sorrentino
- Department of Chemistry and Biochemistry, University of California, Los Angeles, CA, USA
| | - Neil K. Garg
- Department of Chemistry and Biochemistry, University of California, Los Angeles, CA, USA
| | - Dinesh S. Rao
- Department of Pathology and Laboratory Medicine, University of California, Los Angeles, CA, USA
- Jonsson Comprehensive Cancer Center, University of California Los Angeles, CA, USA
- Broad Stem Cell Research Center, University of California, Los Angeles, CA, USA
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2
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García-Blay Ó, Verhagen PGA, Martin B, Hansen MMK. Exploring the role of transcriptional and post-transcriptional processes in mRNA co-expression. Bioessays 2023; 45:e2300130. [PMID: 37926676 DOI: 10.1002/bies.202300130] [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: 07/12/2023] [Revised: 09/18/2023] [Accepted: 10/09/2023] [Indexed: 11/07/2023]
Abstract
Co-expression of two or more genes at the single-cell level is usually associated with functional co-regulation. While mRNA co-expression-measured as the correlation in mRNA levels-can be influenced by both transcriptional and post-transcriptional events, transcriptional regulation is typically considered dominant. We review and connect the literature describing transcriptional and post-transcriptional regulation of co-expression. To enhance our understanding, we integrate four datasets spanning single-cell gene expression data, single-cell promoter activity data and individual transcript half-lives. Confirming expectations, we find that positive co-expression necessitates promoter coordination and similar mRNA half-lives. Surprisingly, negative co-expression is favored by differences in mRNA half-lives, contrary to initial predictions from stochastic simulations. Notably, this association manifests specifically within clusters of genes. We further observe a striking compensation between promoter coordination and mRNA half-lives, which additional stochastic simulations suggest might give rise to the observed co-expression patterns. These findings raise intriguing questions about the functional advantages conferred by this compensation between distal kinetic steps.
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Affiliation(s)
- Óscar García-Blay
- Institute for Molecules and Materials, Radboud University, AJ, Nijmegen, the Netherlands
| | - Pieter G A Verhagen
- Institute for Molecules and Materials, Radboud University, AJ, Nijmegen, the Netherlands
| | - Benjamin Martin
- Institute for Molecules and Materials, Radboud University, AJ, Nijmegen, the Netherlands
| | - Maike M K Hansen
- Institute for Molecules and Materials, Radboud University, AJ, Nijmegen, the Netherlands
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3
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Dai X, Cai L, Zhang Z, Li J. SNRPD1 conveys prognostic value on breast cancer survival and is required for anthracycline sensitivity. BMC Cancer 2023; 23:376. [PMID: 37098488 PMCID: PMC10126993 DOI: 10.1186/s12885-023-10860-z] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/08/2020] [Accepted: 03/27/2023] [Indexed: 04/27/2023] Open
Abstract
BACKGROUND Cancers harboring spliceosome mutations are highly sensitive to additional perturbations on the spliceosome that leads to the development of onco-therapeutics targeting the spliceosome and opens novel opportunities for managing aggressive tumors lacking effective treatment options such as triple negative breast cancers. Being the core spliceosome associated proteins, SNRPD1 and SNRPE have been both proposed as therapeutic targets for breast cancer management. Yet, their differences regarding their prognostic and therapeutic use as well as roles during carcinogenesis are largely unreported. METHODS We conducted in silico analysis at gene expression and genetic levels to differentiate the clinical relevance of SNRPD1 and SNRPE, and explored their differential functionalities and molecular mechanistic associations with cancer in vitro. RESULTS We showed that high SNRPD1 gene expression was prognostic of poor breast cancer survival whereas SNRPE was not. The SNRPD1 expression quantitative trait loci, rs6733100, was found independently prognostic of breast cancer survival using TCGA data. Silencing either SNRPD1 or SNRPE independently suppressed the growth of breast cancer cells, but decreased migration was only observed in SNRPD1-silenced cells. Knocking down SNRPD1 but not SNRPE triggers doxorubicin resistance in triple negative breast cancer cells. Gene enrichment and network analyses revealed the dynamic regulatory role of SNRPD1 on cell cycle and genome stability, and the preventive role of SNRPE against cancer stemness that may neutralize its promotive role on cancer cell proliferation. CONCLUSION Our results differentiated the functionalities of SNRPD1 and SNRPE at both prognostic and therapeutic levels, and preliminarily explained the driving mechanism that requires additional explorations and validations.
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Affiliation(s)
- Xiaofeng Dai
- The First Affiliated Hospital of Xi'an Jiaotong University, Xi'an 710061, China.
- Wuxi School of Medicine, Jiangnan University, Wuxi, 214122, China.
| | - Linhan Cai
- Wuxi School of Medicine, Jiangnan University, Wuxi, 214122, China
| | - Zhifa Zhang
- Wuxi School of Medicine, Jiangnan University, Wuxi, 214122, China
| | - Jitian Li
- Henan Luoyang Orthopedic Hospital (Henan Provincial Orthopedic Hospital), Henan University of Chinese Medicine, Zhengzhou, 450000, China.
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4
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Fu X, Kaur H, Rodgers ML, Montemayor EJ, Butcher SE, Hoskins AA. Identification of transient intermediates during spliceosome activation by single molecule fluorescence microscopy. Proc Natl Acad Sci U S A 2022; 119:e2206815119. [PMID: 36417433 PMCID: PMC9860250 DOI: 10.1073/pnas.2206815119] [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: 04/23/2022] [Accepted: 10/05/2022] [Indexed: 11/24/2022] Open
Abstract
Spliceosome activation is the process of creating the catalytic site for RNA splicing and occurs de novo on each intron following spliceosome assembly. Dozens of factors bind to or are released from the activating spliceosome including the Lsm2-8 heteroheptameric ring that binds the U6 small nuclear RNA 3'-end. Lsm2-8 must be released to permit active site stabilization by the Prp19-containing complex (NineTeen Complex, NTC); however, little is known about the temporal order of events and dynamic interactions that lead up to and follow Lsm2-8 release. We have used colocalization single molecule spectroscopy (CoSMoS) to visualize Lsm2-8 dynamics during activation of Saccharomyces cerevisiae spliceosomes in vitro. Lsm2-8 is recruited as a component of the tri-snRNP and is released after integration of the Prp19-containing complex (NTC). Despite Lsm2-8 and the NTC being mutually exclusive in existing cryo-EM structures of yeast B complex spliceosomes, we identify a transient intermediate containing both ([Formula: see text]) and provide a kinetic framework for its formation and transformation during activation. Prior to [Formula: see text] assembly, the NTC rapidly and reversibly samples the spliceosome suggesting a mechanism for preventing NTC sequestration by defective spliceosomes that fail to properly activate. In complementary ensemble assays, we show that a base-pairing-dependent ternary complex can form between Lsm2-8 and U2 and U6 helix II RNAs. We propose that this interaction may play a role in formation of transient spliceosome intermediates formed during activation.
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Affiliation(s)
- Xingyang Fu
- Department of Chemistry, University of Wisconsin-Madison, Madison, WI53706
| | - Harpreet Kaur
- Department of Biochemistry, University of Wisconsin-Madison, Madison, WI53706
| | - Margaret L. Rodgers
- Department of Biochemistry, University of Wisconsin-Madison, Madison, WI53706
| | - Eric J. Montemayor
- Department of Biochemistry, University of Wisconsin-Madison, Madison, WI53706
| | - Samuel E. Butcher
- Department of Biochemistry, University of Wisconsin-Madison, Madison, WI53706
| | - Aaron A. Hoskins
- Department of Chemistry, University of Wisconsin-Madison, Madison, WI53706
- Department of Biochemistry, University of Wisconsin-Madison, Madison, WI53706
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5
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Hussain N, Rasool F, Khan S, Saleem M, Maheshwari M. Advances in the Synthesis of Natural Products and Medicinally Relevant Molecules from Glycals. ChemistrySelect 2022. [DOI: 10.1002/slct.202201873] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Affiliation(s)
- Nazar Hussain
- Department of Medicinal Chemistry Banaras Hindu University India
| | - Faheem Rasool
- Department of Chemistry Govt. College for Women, Parade Ground Jammu 180001 India
| | - Shahnawaz Khan
- Department of Chemistry Central University of Jammu 180001 Jammu India
| | - Mohd Saleem
- Department of Chemistry Govt.Postgraduate college Rajouri India
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6
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Peng Q, Zhou Y, Oyang L, Wu N, Tang Y, Su M, Luo X, Wang Y, Sheng X, Ma J, Liao Q. Impacts and mechanisms of alternative mRNA splicing in cancer metabolism, immune response, and therapeutics. Mol Ther 2022; 30:1018-1035. [PMID: 34793975 PMCID: PMC8899522 DOI: 10.1016/j.ymthe.2021.11.010] [Citation(s) in RCA: 22] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/14/2021] [Revised: 10/29/2021] [Accepted: 11/11/2021] [Indexed: 02/08/2023] Open
Abstract
Alternative pre-mRNA splicing (AS) provides the potential to produce diversity at RNA and protein levels. Disruptions in the regulation of pre-mRNA splicing can lead to diseases. With the development of transcriptome and genome sequencing technology, increasing diseases have been identified to be associated with abnormal splicing of mRNAs. In tumors, abnormal alternative splicing frequently plays critical roles in cancer pathogenesis and may be considered as new biomarkers and therapeutic targets for cancer intervention. Metabolic abnormalities and immune disorders are important hallmarks of cancer. AS produces multiple different isoforms and diversifies protein expression, which is utilized by the immune and metabolic reprogramming systems to expand gene functions. The abnormal splicing events contributed to tumor progression, partially due to effects on immune response and metabolic reprogramming. Herein, we reviewed the vital role of alternative splicing in regulating cancer metabolism and immune response. We discussed how alternative splicing regulates metabolic reprogramming of cancer cells and antitumor immune response, and the possible strategies to targeting alternative splicing pathways or splicing-regulated metabolic pathway in the context of anticancer immunotherapy. Further, we highlighted the challenges and discuss the perspectives for RNA-based strategies for the treatment of cancer with abnormally alternative splicing isoforms.
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Affiliation(s)
- Qiu Peng
- Hunan Key Laboratory of Cancer Metabolism, Hunan Cancer Hospital and the Affiliated Cancer Hospital of Xiangya School of Medicine, Central South University, Changsha, 410013 Hunan, China,Cancer Research Institute and School of Basic Medical Science, Central South University, Changsha, China
| | - Yujuan Zhou
- Hunan Key Laboratory of Cancer Metabolism, Hunan Cancer Hospital and the Affiliated Cancer Hospital of Xiangya School of Medicine, Central South University, Changsha, 410013 Hunan, China,Hunan Key Laboratory of Translational Radiation Oncology, 283 Tongzipo Road, Changsha 410013, Hunan, China
| | - Linda Oyang
- Hunan Key Laboratory of Cancer Metabolism, Hunan Cancer Hospital and the Affiliated Cancer Hospital of Xiangya School of Medicine, Central South University, Changsha, 410013 Hunan, China
| | - Nayiyuan Wu
- Hunan Key Laboratory of Cancer Metabolism, Hunan Cancer Hospital and the Affiliated Cancer Hospital of Xiangya School of Medicine, Central South University, Changsha, 410013 Hunan, China
| | - Yanyan Tang
- Hunan Key Laboratory of Cancer Metabolism, Hunan Cancer Hospital and the Affiliated Cancer Hospital of Xiangya School of Medicine, Central South University, Changsha, 410013 Hunan, China
| | - Min Su
- Hunan Key Laboratory of Cancer Metabolism, Hunan Cancer Hospital and the Affiliated Cancer Hospital of Xiangya School of Medicine, Central South University, Changsha, 410013 Hunan, China
| | - Xia Luo
- Hunan Key Laboratory of Cancer Metabolism, Hunan Cancer Hospital and the Affiliated Cancer Hospital of Xiangya School of Medicine, Central South University, Changsha, 410013 Hunan, China
| | - Ying Wang
- Hunan Key Laboratory of Cancer Metabolism, Hunan Cancer Hospital and the Affiliated Cancer Hospital of Xiangya School of Medicine, Central South University, Changsha, 410013 Hunan, China
| | - Xiaowu Sheng
- Hunan Key Laboratory of Cancer Metabolism, Hunan Cancer Hospital and the Affiliated Cancer Hospital of Xiangya School of Medicine, Central South University, Changsha, 410013 Hunan, China
| | - Jian Ma
- Hunan Key Laboratory of Cancer Metabolism, Hunan Cancer Hospital and the Affiliated Cancer Hospital of Xiangya School of Medicine, Central South University, Changsha, 410013 Hunan, China; Cancer Research Institute and School of Basic Medical Science, Central South University, Changsha, China.
| | - Qianjin Liao
- Hunan Key Laboratory of Cancer Metabolism, Hunan Cancer Hospital and the Affiliated Cancer Hospital of Xiangya School of Medicine, Central South University, Changsha, 410013 Hunan, China; Hunan Key Laboratory of Translational Radiation Oncology, 283 Tongzipo Road, Changsha 410013, Hunan, China.
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7
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Idrissou M, Maréchal A. The PRP19 Ubiquitin Ligase, Standing at the Cross-Roads of mRNA Processing and Genome Stability. Cancers (Basel) 2022; 14:cancers14040878. [PMID: 35205626 PMCID: PMC8869861 DOI: 10.3390/cancers14040878] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/22/2021] [Revised: 02/01/2022] [Accepted: 02/04/2022] [Indexed: 12/07/2022] Open
Abstract
mRNA processing factors are increasingly being recognized as important regulators of genome stability. By preventing and resolving RNA:DNA hybrids that form co-transcriptionally, these proteins help avoid replication-transcription conflicts and thus contribute to genome stability through their normal function in RNA maturation. Some of these factors also have direct roles in the activation of the DNA damage response and in DNA repair. One of the most intriguing cases is that of PRP19, an evolutionarily conserved essential E3 ubiquitin ligase that promotes mRNA splicing, but also participates directly in ATR activation, double-strand break resection and mitosis. Here, we review historical and recent work on PRP19 and its associated proteins, highlighting their multifarious cellular functions as central regulators of spliceosome activity, R-loop homeostasis, DNA damage signaling and repair and cell division. Finally, we discuss open questions that are bound to shed further light on the functions of PRP19-containing complexes in both normal and cancer cells.
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Affiliation(s)
- Mouhamed Idrissou
- Faculty of Sciences, Department of Biology, Université de Sherbrooke, Sherbrooke, QC J1K 2R1, Canada;
- Centre de Recherche du Centre Hospitalier Universitaire de Sherbrooke, Sherbrooke, QC J1H 5N3, Canada
| | - Alexandre Maréchal
- Faculty of Sciences, Department of Biology, Université de Sherbrooke, Sherbrooke, QC J1K 2R1, Canada;
- Centre de Recherche du Centre Hospitalier Universitaire de Sherbrooke, Sherbrooke, QC J1H 5N3, Canada
- Correspondence:
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8
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Rahman N, Sun J, Li Z, Pattnaik A, Mohallem R, Wang M, Kazemian M, Aryal UK, Andrisani O. The cytoplasmic LSm1-7 and nuclear LSm2-8 complexes exert opposite effects on Hepatitis B virus biosynthesis and interferon responses. Front Immunol 2022; 13:970130. [PMID: 36016928 PMCID: PMC9396650 DOI: 10.3389/fimmu.2022.970130] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/15/2022] [Accepted: 07/15/2022] [Indexed: 12/12/2022] Open
Abstract
Despite many studies on host or viral gene expression, how the cellular proteome responds to internal or external cues during the infection process remains unclear. In this study, we used a Hepatitis B Virus (HBV) replication model and performed proteomic analyses to understand how HBV evades innate immunity as a function of cell cycle progression. Specifically, we performed proteomic analyses of HBV-replicating cells in G1/S and G2/M phases, as a function of IFN-α treatment. We identified that the conserved LSm (Like-Sm1-8) proteins were differentially regulated in HBV replicating cells treated with IFN-α. Specifically, in G2/M phase, IFN-α increased protein level of LSm1, the unique subunit of cytoplasmic LSm1-7 complex involved in mRNA decay. By contrast, IFN-α decreased LSm8, the unique subunit of nuclear LSm2-8 complex, a chaperone of U6 spliceosomal RNA, suggesting the cytoplasmic LSm1-7 complex is antiviral, whereas the nuclear LSm2-8 complex is pro-viral. In HBV replication and infection models, siRNA-mediated knockdown of LSm1 increased all viral RNAs. Conversely, LSm8 knockdown reduced viral RNA levels, dependent on N6-adenosine methylation (m6A) of the epsilon stem-loop at the 5' end of pre-Core/pregenomic (preC/pg) RNA. Methylated RNA immunoprecipitation (MeRIP) assays demonstrated reduced viral RNA methylation by LSm8 knockdown, dependent on the 5' m6A modification, suggesting the LSm2-8 complex has a role in mediating this modification. Interestingly, splicing inhibitor Cp028 acting upstream of the LSm2-8 complex suppressed viral RNA levels without reducing the 5' m6A modification. This observation suggests Cp028 has novel antiviral effects, likely potentiating IFN-α-mediated suppression of HBV biosynthesis.
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Affiliation(s)
- Naimur Rahman
- Department of Basic Medical Sciences, Purdue University, West Lafayette, IN, United States.,Purdue Center for Cancer Research, Purdue University, West Lafayette, IN, United States
| | - Jiazeng Sun
- Department of Basic Medical Sciences, Purdue University, West Lafayette, IN, United States.,Purdue Center for Cancer Research, Purdue University, West Lafayette, IN, United States
| | - Zhili Li
- Department of Basic Medical Sciences, Purdue University, West Lafayette, IN, United States.,Purdue Center for Cancer Research, Purdue University, West Lafayette, IN, United States
| | - Aryamav Pattnaik
- Purdue Center for Cancer Research, Purdue University, West Lafayette, IN, United States.,Department of Biochemistry, Purdue University, West Lafayette, IN, United States
| | - Rodrigo Mohallem
- Purdue Proteomics Facility, Bindley Bioscience Center, Purdue University, West Lafayette, IN, United States.,Department of Comparative Pathobiology, Purdue University, West Lafayette, IN, United States
| | - Mengbo Wang
- Purdue Center for Cancer Research, Purdue University, West Lafayette, IN, United States.,Department of Biochemistry, Purdue University, West Lafayette, IN, United States
| | - Majid Kazemian
- Purdue Center for Cancer Research, Purdue University, West Lafayette, IN, United States.,Department of Biochemistry, Purdue University, West Lafayette, IN, United States.,Department of Computer Science, Purdue University, West Lafayette, IN, United States
| | - Uma K Aryal
- Purdue Proteomics Facility, Bindley Bioscience Center, Purdue University, West Lafayette, IN, United States.,Department of Comparative Pathobiology, Purdue University, West Lafayette, IN, United States
| | - Ourania Andrisani
- Department of Basic Medical Sciences, Purdue University, West Lafayette, IN, United States.,Purdue Center for Cancer Research, Purdue University, West Lafayette, IN, United States
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9
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Impact of Alternative Splicing Variants on Liver Cancer Biology. Cancers (Basel) 2021; 14:cancers14010018. [PMID: 35008179 PMCID: PMC8750444 DOI: 10.3390/cancers14010018] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/19/2021] [Revised: 12/15/2021] [Accepted: 12/16/2021] [Indexed: 12/24/2022] Open
Abstract
Simple Summary Among the top ten deadly solid tumors are the two most frequent liver cancers, hepatocellular carcinoma, and intrahepatic cholangiocarcinoma, whose development and malignancy are favored by multifactorial conditions, which include aberrant maturation of pre-mRNA due to abnormalities in either the machinery involved in the splicing, i.e., the spliceosome and associated factors, or the nucleotide sequences of essential sites for the exon recognition process. As a consequence of cancer-associated aberrant splicing in hepatocytes- and cholangiocytes-derived cancer cells, abnormal proteins are synthesized. They contribute to the dysregulated proliferation and eventually transformation of these cells to phenotypes with enhanced invasiveness, migration, and multidrug resistance, which contributes to the poor prognosis that characterizes these liver cancers. Abstract The two most frequent primary cancers affecting the liver, whose incidence is growing worldwide, are hepatocellular carcinoma (HCC) and intrahepatic cholangiocarcinoma (iCCA), which are among the five most lethal solid tumors with meager 5-year survival rates. The common difficulty in most cases to reach an early diagnosis, the aggressive invasiveness of both tumors, and the lack of favorable response to pharmacotherapy, either classical chemotherapy or modern targeted therapy, account for the poor outcome of these patients. Alternative splicing (AS) during pre-mRNA maturation results in changes that might affect proteins involved in different aspects of cancer biology, such as cell cycle dysregulation, cytoskeleton disorganization, migration, and adhesion, which favors carcinogenesis, tumor promotion, and progression, allowing cancer cells to escape from pharmacological treatments. Reasons accounting for cancer-associated aberrant splicing include mutations that create or disrupt splicing sites or splicing enhancers or silencers, abnormal expression of splicing factors, and impaired signaling pathways affecting the activity of the splicing machinery. Here we have reviewed the available information regarding the impact of AS on liver carcinogenesis and the development of malignant characteristics of HCC and iCCA, whose understanding is required to develop novel therapeutical approaches aimed at manipulating the phenotype of cancer cells.
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10
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Genome-Wide RNAi Screening Identifies Novel Pathways/Genes Involved in Oxidative Stress and Repurposable Drugs to Preserve Cystic Fibrosis Airway Epithelial Cell Integrity. Antioxidants (Basel) 2021; 10:antiox10121936. [PMID: 34943039 PMCID: PMC8750174 DOI: 10.3390/antiox10121936] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/08/2021] [Revised: 11/23/2021] [Accepted: 11/27/2021] [Indexed: 12/20/2022] Open
Abstract
Recurrent infection-inflammation cycles in cystic fibrosis (CF) patients generate a highly oxidative environment, leading to progressive destruction of the airway epithelia. The identification of novel modifier genes involved in oxidative stress susceptibility in the CF airways might contribute to devise new therapeutic approaches. We performed an unbiased genome-wide RNAi screen using a randomized siRNA library to identify oxidative stress modulators in CF airway epithelial cells. We monitored changes in cell viability after a lethal dose of hydrogen peroxide. Local similarity and protein-protein interaction network analyses uncovered siRNA target genes/pathways involved in oxidative stress. Further mining against public drug databases allowed identifying and validating commercially available drugs conferring oxidative stress resistance. Accordingly, a catalog of 167 siRNAs able to confer oxidative stress resistance in CF submucosal gland cells targeted 444 host genes and multiple circuitries involved in oxidative stress. The most significant processes were related to alternative splicing and cell communication, motility, and remodeling (impacting cilia structure/function, and cell guidance complexes). Other relevant pathways included DNA repair and PI3K/AKT/mTOR signaling. The mTOR inhibitor everolimus, the α1-adrenergic receptor antagonist doxazosin, and the Syk inhibitor fostamatinib significantly increased the viability of CF submucosal gland cells under strong oxidative stress pressure. Thus, novel therapeutic strategies to preserve airway cell integrity from the harsh oxidative milieu of CF airways could stem from a deep understanding of the complex consequences of oxidative stress at the molecular level, followed by a rational repurposing of existing "protective" drugs. This approach could also prove useful to other respiratory pathologies.
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DHX15-independent roles for TFIP11 in U6 snRNA modification, U4/U6.U5 tri-snRNP assembly and pre-mRNA splicing fidelity. Nat Commun 2021; 12:6648. [PMID: 34789764 PMCID: PMC8599867 DOI: 10.1038/s41467-021-26932-2] [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: 12/04/2020] [Accepted: 10/22/2021] [Indexed: 11/29/2022] Open
Abstract
The U6 snRNA, the core catalytic component of the spliceosome, is extensively modified post-transcriptionally, with 2'-O-methylation being most common. However, how U6 2'-O-methylation is regulated remains largely unknown. Here we report that TFIP11, the human homolog of the yeast spliceosome disassembly factor Ntr1, localizes to nucleoli and Cajal Bodies and is essential for the 2'-O-methylation of U6. Mechanistically, we demonstrate that TFIP11 knockdown reduces the association of U6 snRNA with fibrillarin and associated snoRNAs, therefore altering U6 2'-O-methylation. We show U6 snRNA hypomethylation is associated with changes in assembly of the U4/U6.U5 tri-snRNP leading to defects in spliceosome assembly and alterations in splicing fidelity. Strikingly, this function of TFIP11 is independent of the RNA helicase DHX15, its known partner in yeast. In sum, our study demonstrates an unrecognized function for TFIP11 in U6 snRNP modification and U4/U6.U5 tri-snRNP assembly, identifying TFIP11 as a critical spliceosome assembly regulator.
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12
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Impact of alternative splicing on mechanisms of resistance to anticancer drugs. Biochem Pharmacol 2021; 193:114810. [PMID: 34673012 DOI: 10.1016/j.bcp.2021.114810] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/20/2021] [Revised: 10/05/2021] [Accepted: 10/06/2021] [Indexed: 12/15/2022]
Abstract
A shared characteristic of many tumors is the lack of response to anticancer drugs. Multiple mechanisms of pharmacoresistance (MPRs) are involved in permitting cancer cells to overcome the effect of these agents. Pharmacoresistance can be primary (intrinsic) or secondary (acquired), i.e., triggered or enhanced in response to the treatment. Moreover, MPRs usually result in the lack of sensitivity to several agents, which accounts for diverse multidrug-resistant (MDR) phenotypes. MPRs are based on the dynamic expression of more than one hundred genes, constituting the so-called resistome. Alternative splicing (AS) during pre-mRNA maturation results in changes affecting proteins involved in the resistome. The resulting splicing variants (SVs) reduce the efficacy of anticancer drugs by lowering the intracellular levels of active agents, altering molecular targets, enhancing both DNA repair ability and defensive mechanism of tumors, inducing changes in the balance between pro-survival and pro-apoptosis signals, modifying interactions with the tumor microenvironment, and favoring malignant phenotypic transitions. Reasons accounting for cancer-associated aberrant splicing include mutations that create or disrupt splicing sites or splicing enhancers or silencers, abnormal expression of splicing factors, and impaired signaling pathways affecting the activity of the splicing machinery. Here we have reviewed the impact of AS on MPR in cancer cells.
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13
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A synthetic small molecule stalls pre-mRNA splicing by promoting an early-stage U2AF2-RNA complex. Cell Chem Biol 2021; 28:1145-1157.e6. [PMID: 33689684 PMCID: PMC8380659 DOI: 10.1016/j.chembiol.2021.02.007] [Citation(s) in RCA: 13] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/13/2020] [Revised: 01/25/2021] [Accepted: 02/11/2021] [Indexed: 12/20/2022]
Abstract
Dysregulated pre-mRNA splicing is an emerging Achilles heel of cancers and myelodysplasias. To expand the currently limited portfolio of small-molecule drug leads, we screened for chemical modulators of the U2AF complex, which nucleates spliceosome assembly and is mutated in myelodysplasias. A hit compound specifically enhances RNA binding by a U2AF2 subunit. Remarkably, the compound inhibits splicing of representative substrates and stalls spliceosome assembly at the stage of U2AF function. Computational docking, together with structure-guided mutagenesis, indicates that the compound bridges the tandem U2AF2 RNA recognition motifs via hydrophobic and electrostatic moieties. Cells expressing a cancer-associated U2AF1 mutant are preferentially killed by treatment with the compound. Altogether, our results highlight the potential of trapping early spliceosome assembly as an effective pharmacological means to manipulate pre-mRNA splicing. By extension, we suggest that stabilizing assembly intermediates may offer a useful approach for small-molecule inhibition of macromolecular machines.
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14
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Supadmanaba IGP, Mantini G, Randazzo O, Capula M, Muller IB, Cascioferro S, Diana P, Peters GJ, Giovannetti E. Interrelationship between miRNA and splicing factors in pancreatic ductal adenocarcinoma. Epigenetics 2021; 17:381-404. [PMID: 34057028 PMCID: PMC8993068 DOI: 10.1080/15592294.2021.1916697] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023] Open
Abstract
Pancreatic ductal adenocarcinoma (PDAC) is one of the most lethal cancers because of diagnosis at late stage and inherent/acquired chemoresistance. Recent advances in genomic profiling and biology of this disease have not yet been translated to a relevant improvement in terms of disease management and patient’s survival. However, new possibilities for treatment may emerge from studies on key epigenetic factors. Deregulation of microRNA (miRNA) dependent gene expression and mRNA splicing are epigenetic processes that modulate the protein repertoire at the transcriptional level. These processes affect all aspects of PDAC pathogenesis and have great potential to unravel new therapeutic targets and/or biomarkers. Remarkably, several studies showed that they actually interact with each other in influencing PDAC progression. Some splicing factors directly interact with specific miRNAs and either facilitate or inhibit their expression, such as Rbfox2, which cleaves the well-known oncogenic miRNA miR-21. Conversely, miR-15a-5p and miR-25-3p significantly downregulate the splicing factor hnRNPA1 which acts also as a tumour suppressor gene and is involved in processing of miR-18a, which in turn, is a negative regulator of KRAS expression. Therefore, this review describes the interaction between splicing and miRNA, as well as bioinformatic tools to explore the effect of splicing modulation towards miRNA profiles, in order to exploit this interplay for the development of innovative treatments. Targeting aberrant splicing and deregulated miRNA, alone or in combination, may hopefully provide novel therapeutic approaches to fight the complex biology and the common treatment recalcitrance of PDAC.
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Affiliation(s)
- I Gede Putu Supadmanaba
- Department of Medical Oncology, Cancer Center Amsterdam, Amsterdam UMC, VU University Medical Center (VUMC), Amsterdam, The Netherlands.,Biochemistry Department, Faculty of Medicine, Universitas Udayana, Denpasar, Bali, Indonesia
| | - Giulia Mantini
- Department of Medical Oncology, Cancer Center Amsterdam, Amsterdam UMC, VU University Medical Center (VUMC), Amsterdam, The Netherlands.,Cancer Pharmacology Lab, AIRC Start up Unit, Fondazione Pisana per La Scienza, Pisa, Italy
| | - Ornella Randazzo
- Department of Medical Oncology, Cancer Center Amsterdam, Amsterdam UMC, VU University Medical Center (VUMC), Amsterdam, The Netherlands.,Dipartimento Di Scienze E Tecnologie Biologiche Chimiche E Farmaceutiche (STEBICEF), Università Degli Studi Di Palermo, Palermo, Italy
| | - Mjriam Capula
- Cancer Pharmacology Lab, AIRC Start up Unit, Fondazione Pisana per La Scienza, Pisa, Italy.,Institute of Life Sciences, Sant'Anna School of Advanced Studies, Pisa, Italy
| | - Ittai B Muller
- Department of Clinical Chemistry, Amsterdam UMC, VU University Medical Center (VUMC), Amsterdam, The Netherlands
| | - Stella Cascioferro
- Dipartimento Di Scienze E Tecnologie Biologiche Chimiche E Farmaceutiche (STEBICEF), Università Degli Studi Di Palermo, Palermo, Italy
| | - Patrizia Diana
- Dipartimento Di Scienze E Tecnologie Biologiche Chimiche E Farmaceutiche (STEBICEF), Università Degli Studi Di Palermo, Palermo, Italy
| | - Godefridus J Peters
- Department of Medical Oncology, Cancer Center Amsterdam, Amsterdam UMC, VU University Medical Center (VUMC), Amsterdam, The Netherlands.,Department of Biochemistry, Medical University of Gdansk, Poland
| | - Elisa Giovannetti
- Department of Medical Oncology, Cancer Center Amsterdam, Amsterdam UMC, VU University Medical Center (VUMC), Amsterdam, The Netherlands.,Cancer Pharmacology Lab, AIRC Start up Unit, Fondazione Pisana per La Scienza, Pisa, Italy
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15
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Ghosh AK, Mishevich JL, Jurica MS. Spliceostatins and Derivatives: Chemical Syntheses and Biological Properties of Potent Splicing Inhibitors. JOURNAL OF NATURAL PRODUCTS 2021; 84:1681-1706. [PMID: 33974423 PMCID: PMC8919379 DOI: 10.1021/acs.jnatprod.1c00100] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/25/2023]
Abstract
Spliceostatins and thailanstatins are intriguing natural products due to their structural features as well as their biological significance. This family of natural products has been the subject of immense synthetic interest because they exhibit very potent cytotoxicity in representative human cancer cell lines. The cytotoxic properties of these natural products are related to their ability to inhibit spliceosomes. FR901564 and spliceostatins have been shown to inhibit spliceosomes by binding to their SF3B component. Structurally, these natural products contain two highly functionalized tetrahydropyran rings with multiple stereogenic centers joined by a diene moiety and an acyclic side chain linked with an amide bond. Total syntheses of this family of natural products led to the development of useful synthetic strategies, which enabled the synthesis of potent derivatives. The spliceosome modulating properties of spliceostatins and synthetic derivatives opened the door for understanding the underlying spliceosome mechanism as well as the development of new therapies based upon small-molecule splicing modulators. This review outlines the total synthesis of spliceostatins, synthetic studies of structural derivatives, and their bioactivity.
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Affiliation(s)
- Arun K Ghosh
- Department of Chemistry and Department of Medicinal Chemistry, Purdue University, 560 Oval Drive, West Lafayette, Indiana 47907, United States
| | - Jennifer L Mishevich
- Department of Chemistry and Department of Medicinal Chemistry, Purdue University, 560 Oval Drive, West Lafayette, Indiana 47907, United States
| | - Melissa S Jurica
- Department of Molecular, Cell and Developmental Biology and Center for Molecular Biology of RNA, University of California, Santa Cruz, California 95064, United States
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16
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Biology of the mRNA Splicing Machinery and Its Dysregulation in Cancer Providing Therapeutic Opportunities. Int J Mol Sci 2021; 22:ijms22105110. [PMID: 34065983 PMCID: PMC8150589 DOI: 10.3390/ijms22105110] [Citation(s) in RCA: 19] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/06/2021] [Revised: 05/07/2021] [Accepted: 05/07/2021] [Indexed: 12/13/2022] Open
Abstract
Dysregulation of messenger RNA (mRNA) processing—in particular mRNA splicing—is a hallmark of cancer. Compared to normal cells, cancer cells frequently present aberrant mRNA splicing, which promotes cancer progression and treatment resistance. This hallmark provides opportunities for developing new targeted cancer treatments. Splicing of precursor mRNA into mature mRNA is executed by a dynamic complex of proteins and small RNAs called the spliceosome. Spliceosomes are part of the supraspliceosome, a macromolecular structure where all co-transcriptional mRNA processing activities in the cell nucleus are coordinated. Here we review the biology of the mRNA splicing machinery in the context of other mRNA processing activities in the supraspliceosome and present current knowledge of its dysregulation in lung cancer. In addition, we review investigations to discover therapeutic targets in the spliceosome and give an overview of inhibitors and modulators of the mRNA splicing process identified so far. Together, this provides insight into the value of targeting the spliceosome as a possible new treatment for lung cancer.
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17
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Marima R, Hull R, Mathabe K, Setlai B, Batra J, Sartor O, Mehrotra R, Dlamini Z. Prostate cancer racial, socioeconomic, geographic disparities: targeting the genomic landscape and splicing events in search for diagnostic, prognostic and therapeutic targets. Am J Cancer Res 2021; 11:1012-1030. [PMID: 33948343 PMCID: PMC8085879] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/12/2020] [Accepted: 01/25/2021] [Indexed: 06/12/2023] Open
Abstract
Prostate cancer (PCa) is one of the leading causes of deaths in men globally. This is a heterogeneous and complex disease that urgently warrants further insight into its pathology. Developed countries have thus far the highest PCa incidence rates, with comparatively low mortality rates. Even though PCa in the Asian population seems to have high incidence and mortality rates, the African countries are emerging as the focal center for this disease. It has also been reported that the Sub-Saharan (SSA) countries have both the highest incidence and mortality rates. To date, few studies have reported the link between PCa and African populations. Adequate evidence is still missing to fully comprehend this relationship. While it has been brought to attention that racial, geographical and socioeconomic status are contributing factors, men of African descent across the globe, irrespective of their geographical position have higher PCa incidence and mortality rates compared to their white counterparts. To date, hormone therapy is the mainstay treatment of PCa, while the dysregulation of androgen receptor (AR) signaling is a hallmark of PCa. One of the emerging problems with this therapeutic approach is resistance to antiandrogens, and that AR splice isoforms implicated in the progression of PCa lack the therapeutic ligand-binding domain (LBD) target. AR splice variants targeted therapy is emerging and in clinical trials. Leveraging PCa transcriptomics is key towards PCa precision medicine. The aim of this review is to outline the PCa epidemiology globally and in Africa, PCa associated risk factors, discuss AR signaling and PCa mechanisms, the role of dysregulated splicing in PCa as novel prognostic indicators and therapeutic targets.
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Affiliation(s)
- Rahaba Marima
- SAMRC/UP Precision Prevention and Novel Drug Targets for HIV-Associated Cancers Extramural Unit, Pan African Cancer Research Institute (PACRI), University of PretoriaHatfield 0028, South Africa
| | - Rodney Hull
- SAMRC/UP Precision Prevention and Novel Drug Targets for HIV-Associated Cancers Extramural Unit, Pan African Cancer Research Institute (PACRI), University of PretoriaHatfield 0028, South Africa
| | - Kgomotso Mathabe
- Department of Urology, Faculty of Health Sciences, University of PretoriaHatfield 0028, South Africa
| | - Botle Setlai
- Department of Surgery, Faculty of Health Sciences, University of PretoriaHatfield 0028, South Africa
| | - Jyotsna Batra
- Australian Prostate Cancer Research Centre - Queensland, Translational Research InstituteBrisbane 4102, Australia
- Cancer Program, School of Biomedical Sciences, Institute of Health and Biomedical Innovation, Queensland University of TechnologyBrisbane 4102, Australia
| | - Oliver Sartor
- SAMRC/UP Precision Prevention and Novel Drug Targets for HIV-Associated Cancers Extramural Unit, Pan African Cancer Research Institute (PACRI), University of PretoriaHatfield 0028, South Africa
- Tulane Cancer Center, Tulane Medical SchoolNew Orleans, LA 70112, United States
| | - Ravi Mehrotra
- SAMRC/UP Precision Prevention and Novel Drug Targets for HIV-Associated Cancers Extramural Unit, Pan African Cancer Research Institute (PACRI), University of PretoriaHatfield 0028, South Africa
- India Cancer Research Consortium (ICMR-DHR) Department of Health ResearchRed Cross Road, New Delhi 110001, India
| | - Zodwa Dlamini
- SAMRC/UP Precision Prevention and Novel Drug Targets for HIV-Associated Cancers Extramural Unit, Pan African Cancer Research Institute (PACRI), University of PretoriaHatfield 0028, South Africa
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18
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Natua S, Ashok C, Shukla S. Hypoxia-induced alternative splicing in human diseases: the pledge, the turn, and the prestige. Cell Mol Life Sci 2021; 78:2729-2747. [PMID: 33386889 PMCID: PMC11072330 DOI: 10.1007/s00018-020-03727-0] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/18/2020] [Revised: 11/24/2020] [Accepted: 11/28/2020] [Indexed: 12/30/2022]
Abstract
Maintenance of oxygen homeostasis is an indispensable criterion for the existence of multicellular life-forms. Disruption of this homeostasis due to inadequate oxygenation of the respiring tissues leads to pathological hypoxia, which acts as a significant stressor in several pathophysiological conditions including cancer, cardiovascular defects, bacterial infections, and neurological disorders. Consequently, the hypoxic tissues develop necessary adaptations both at the tissue and cellular level. The cellular adaptations involve a dramatic alteration in gene expression, post-transcriptional and post-translational modification of gene products, bioenergetics, and metabolism. Among the key responses to oxygen-deprivation is the skewing of cellular alternative splicing program. Herein, we discuss the current concepts of oxygen tension-dependent alternative splicing relevant to various pathophysiological conditions. Following a brief description of cellular response to hypoxia and the pre-mRNA splicing mechanism, we outline the impressive number of hypoxia-elicited alternative splicing events associated with maladies like cancer, cardiovascular diseases, and neurological disorders. Furthermore, we discuss how manipulation of hypoxia-induced alternative splicing may pose promising strategies for novel translational diagnosis and therapeutic interventions.
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Affiliation(s)
- Subhashis Natua
- Department of Biological Sciences, Indian Institute of Science Education and Research Bhopal, Bhopal, 462066, Madhya Pradesh, India
| | - Cheemala Ashok
- Department of Biological Sciences, Indian Institute of Science Education and Research Bhopal, Bhopal, 462066, Madhya Pradesh, India
| | - Sanjeev Shukla
- Department of Biological Sciences, Indian Institute of Science Education and Research Bhopal, Bhopal, 462066, Madhya Pradesh, India.
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19
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Bowling EA, Wang JH, Gong F, Wu W, Neill NJ, Kim IS, Tyagi S, Orellana M, Kurley SJ, Dominguez-Vidaña R, Chung HC, Hsu TYT, Dubrulle J, Saltzman AB, Li H, Meena JK, Canlas GM, Chamakuri S, Singh S, Simon LM, Olson CM, Dobrolecki LE, Lewis MT, Zhang B, Golding I, Rosen JM, Young DW, Malovannaya A, Stossi F, Miles G, Ellis MJ, Yu L, Buonamici S, Lin CY, Karlin KL, Zhang XHF, Westbrook TF. Spliceosome-targeted therapies trigger an antiviral immune response in triple-negative breast cancer. Cell 2021; 184:384-403.e21. [PMID: 33450205 PMCID: PMC8635244 DOI: 10.1016/j.cell.2020.12.031] [Citation(s) in RCA: 94] [Impact Index Per Article: 31.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/25/2019] [Revised: 07/29/2020] [Accepted: 12/21/2020] [Indexed: 12/16/2022]
Abstract
Many oncogenic insults deregulate RNA splicing, often leading to hypersensitivity of tumors to spliceosome-targeted therapies (STTs). However, the mechanisms by which STTs selectively kill cancers remain largely unknown. Herein, we discover that mis-spliced RNA itself is a molecular trigger for tumor killing through viral mimicry. In MYC-driven triple-negative breast cancer, STTs cause widespread cytoplasmic accumulation of mis-spliced mRNAs, many of which form double-stranded structures. Double-stranded RNA (dsRNA)-binding proteins recognize these endogenous dsRNAs, triggering antiviral signaling and extrinsic apoptosis. In immune-competent models of breast cancer, STTs cause tumor cell-intrinsic antiviral signaling, downstream adaptive immune signaling, and tumor cell death. Furthermore, RNA mis-splicing in human breast cancers correlates with innate and adaptive immune signatures, especially in MYC-amplified tumors that are typically immune cold. These findings indicate that dsRNA-sensing pathways respond to global aberrations of RNA splicing in cancer and provoke the hypothesis that STTs may provide unexplored strategies to activate anti-tumor immune pathways.
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Affiliation(s)
- Elizabeth A Bowling
- Verna and Marrs McLean Department of Biochemistry and Molecular Biology, Baylor College of Medicine, Houston, TX 77030, USA
| | - Jarey H Wang
- Verna and Marrs McLean Department of Biochemistry and Molecular Biology, Baylor College of Medicine, Houston, TX 77030, USA; Medical Scientist Training Program, Baylor College of Medicine, Houston, TX 77030, USA
| | - Fade Gong
- Verna and Marrs McLean Department of Biochemistry and Molecular Biology, Baylor College of Medicine, Houston, TX 77030, USA
| | - William Wu
- Verna and Marrs McLean Department of Biochemistry and Molecular Biology, Baylor College of Medicine, Houston, TX 77030, USA; Medical Scientist Training Program, Baylor College of Medicine, Houston, TX 77030, USA
| | - Nicholas J Neill
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, TX 77030, USA
| | - Ik Sun Kim
- Lester and Sue Smith Breast Center, Baylor College of Medicine, Houston, TX 77030, USA
| | - Siddhartha Tyagi
- Verna and Marrs McLean Department of Biochemistry and Molecular Biology, Baylor College of Medicine, Houston, TX 77030, USA
| | - Mayra Orellana
- Verna and Marrs McLean Department of Biochemistry and Molecular Biology, Baylor College of Medicine, Houston, TX 77030, USA
| | - Sarah J Kurley
- Verna and Marrs McLean Department of Biochemistry and Molecular Biology, Baylor College of Medicine, Houston, TX 77030, USA
| | - Rocio Dominguez-Vidaña
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, TX 77030, USA
| | - Hsiang-Ching Chung
- Verna and Marrs McLean Department of Biochemistry and Molecular Biology, Baylor College of Medicine, Houston, TX 77030, USA
| | - Tiffany Y-T Hsu
- Verna and Marrs McLean Department of Biochemistry and Molecular Biology, Baylor College of Medicine, Houston, TX 77030, USA; Medical Scientist Training Program, Baylor College of Medicine, Houston, TX 77030, USA
| | - Julien Dubrulle
- Department of Molecular and Cellular Biology, Baylor College of Medicine, Houston, TX 77030, USA
| | - Alexander B Saltzman
- Verna and Marrs McLean Department of Biochemistry and Molecular Biology, Baylor College of Medicine, Houston, TX 77030, USA
| | - Heyuan Li
- Verna and Marrs McLean Department of Biochemistry and Molecular Biology, Baylor College of Medicine, Houston, TX 77030, USA
| | - Jitendra K Meena
- Verna and Marrs McLean Department of Biochemistry and Molecular Biology, Baylor College of Medicine, Houston, TX 77030, USA
| | - Gino M Canlas
- Verna and Marrs McLean Department of Biochemistry and Molecular Biology, Baylor College of Medicine, Houston, TX 77030, USA; Department of Pharmacology and Chemical Biology, Baylor College of Medicine, Houston, TX 77030, USA
| | - Srinivas Chamakuri
- Department of Pharmacology and Chemical Biology, Baylor College of Medicine, Houston, TX 77030, USA
| | - Swarnima Singh
- Lester and Sue Smith Breast Center, Baylor College of Medicine, Houston, TX 77030, USA
| | - Lukas M Simon
- Therapeutic Innovation Center, Baylor College of Medicine, Houston, TX 77030, USA
| | - Calla M Olson
- Therapeutic Innovation Center, Baylor College of Medicine, Houston, TX 77030, USA
| | - Lacey E Dobrolecki
- Lester and Sue Smith Breast Center, Baylor College of Medicine, Houston, TX 77030, USA
| | - Michael T Lewis
- Lester and Sue Smith Breast Center, Baylor College of Medicine, Houston, TX 77030, USA; Department of Molecular and Cellular Biology, Baylor College of Medicine, Houston, TX 77030, USA; Dan L. Duncan Cancer Center, Baylor College of Medicine, Houston, TX 77030, USA
| | - Bing Zhang
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, TX 77030, USA; Lester and Sue Smith Breast Center, Baylor College of Medicine, Houston, TX 77030, USA; Dan L. Duncan Cancer Center, Baylor College of Medicine, Houston, TX 77030, USA
| | - Ido Golding
- Verna and Marrs McLean Department of Biochemistry and Molecular Biology, Baylor College of Medicine, Houston, TX 77030, USA
| | - Jeffrey M Rosen
- Department of Molecular and Cellular Biology, Baylor College of Medicine, Houston, TX 77030, USA; Dan L. Duncan Cancer Center, Baylor College of Medicine, Houston, TX 77030, USA
| | - Damian W Young
- Department of Pharmacology and Chemical Biology, Baylor College of Medicine, Houston, TX 77030, USA; Therapeutic Innovation Center, Baylor College of Medicine, Houston, TX 77030, USA
| | - Anna Malovannaya
- Verna and Marrs McLean Department of Biochemistry and Molecular Biology, Baylor College of Medicine, Houston, TX 77030, USA
| | - Fabio Stossi
- Department of Molecular and Cellular Biology, Baylor College of Medicine, Houston, TX 77030, USA
| | - George Miles
- Lester and Sue Smith Breast Center, Baylor College of Medicine, Houston, TX 77030, USA; Department of Molecular and Cellular Biology, Baylor College of Medicine, Houston, TX 77030, USA
| | - Matthew J Ellis
- Lester and Sue Smith Breast Center, Baylor College of Medicine, Houston, TX 77030, USA; Department of Molecular and Cellular Biology, Baylor College of Medicine, Houston, TX 77030, USA
| | - Lihua Yu
- H3Biomedicine, Cambridge, MA 02139, USA
| | | | - Charles Y Lin
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, TX 77030, USA; Therapeutic Innovation Center, Baylor College of Medicine, Houston, TX 77030, USA; Dan L. Duncan Cancer Center, Baylor College of Medicine, Houston, TX 77030, USA
| | - Kristen L Karlin
- Therapeutic Innovation Center, Baylor College of Medicine, Houston, TX 77030, USA
| | - Xiang H-F Zhang
- Lester and Sue Smith Breast Center, Baylor College of Medicine, Houston, TX 77030, USA; Dan L. Duncan Cancer Center, Baylor College of Medicine, Houston, TX 77030, USA
| | - Thomas F Westbrook
- Verna and Marrs McLean Department of Biochemistry and Molecular Biology, Baylor College of Medicine, Houston, TX 77030, USA; Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, TX 77030, USA; Lester and Sue Smith Breast Center, Baylor College of Medicine, Houston, TX 77030, USA; Department of Molecular and Cellular Biology, Baylor College of Medicine, Houston, TX 77030, USA; Therapeutic Innovation Center, Baylor College of Medicine, Houston, TX 77030, USA.
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20
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Townsend C, Leelaram MN, Agafonov DE, Dybkov O, Will CL, Bertram K, Urlaub H, Kastner B, Stark H, Lührmann R. Mechanism of protein-guided folding of the active site U2/U6 RNA during spliceosome activation. Science 2020; 370:science.abc3753. [PMID: 33243851 DOI: 10.1126/science.abc3753] [Citation(s) in RCA: 35] [Impact Index Per Article: 8.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/20/2020] [Accepted: 10/23/2020] [Indexed: 01/02/2023]
Abstract
Spliceosome activation involves extensive protein and RNA rearrangements that lead to formation of a catalytically active U2/U6 RNA structure. At present, little is known about the assembly pathway of the latter and the mechanism whereby proteins aid its proper folding. Here, we report the cryo-electron microscopy structures of two human, activated spliceosome precursors (that is, pre-Bact complexes) at core resolutions of 3.9 and 4.2 angstroms. These structures elucidate the order of the numerous protein exchanges that occur during activation, the mutually exclusive interactions that ensure the correct order of ribonucleoprotein rearrangements needed to form the U2/U6 catalytic RNA, and the stepwise folding pathway of the latter. Structural comparisons with mature Bact complexes reveal the molecular mechanism whereby a conformational change in the scaffold protein PRP8 facilitates final three-dimensional folding of the U2/U6 catalytic RNA.
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Affiliation(s)
- Cole Townsend
- Department of Structural Dynamics, MPI for Biophysical Chemistry, Am Fassberg 11, D-37077 Göttingen, Germany
| | - Majety N Leelaram
- Cellular Biochemistry, MPI for Biophysical Chemistry, Am Fassberg 11, D-37077 Göttingen, Germany
| | - Dmitry E Agafonov
- Cellular Biochemistry, MPI for Biophysical Chemistry, Am Fassberg 11, D-37077 Göttingen, Germany
| | - Olexandr Dybkov
- Cellular Biochemistry, MPI for Biophysical Chemistry, Am Fassberg 11, D-37077 Göttingen, Germany
| | - Cindy L Will
- Cellular Biochemistry, MPI for Biophysical Chemistry, Am Fassberg 11, D-37077 Göttingen, Germany
| | - Karl Bertram
- Department of Structural Dynamics, MPI for Biophysical Chemistry, Am Fassberg 11, D-37077 Göttingen, Germany
| | - Henning Urlaub
- Bioanalytical Mass Spectrometry, MPI for Biophysical Chemistry, Am Fassberg 11, D-37077 Göttingen, Germany.,Bioanalytics Group, Institute for Clinical Chemistry, University Medical Center Göttingen, Robert-Koch-Straße 40, D-37075 Göttingen, Germany
| | - Berthold Kastner
- Cellular Biochemistry, MPI for Biophysical Chemistry, Am Fassberg 11, D-37077 Göttingen, Germany.
| | - Holger Stark
- Department of Structural Dynamics, MPI for Biophysical Chemistry, Am Fassberg 11, D-37077 Göttingen, Germany.
| | - Reinhard Lührmann
- Cellular Biochemistry, MPI for Biophysical Chemistry, Am Fassberg 11, D-37077 Göttingen, Germany.
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21
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Identification of phenothiazine derivatives as UHM-binding inhibitors of early spliceosome assembly. Nat Commun 2020; 11:5621. [PMID: 33159082 PMCID: PMC7648758 DOI: 10.1038/s41467-020-19514-1] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/17/2020] [Accepted: 10/16/2020] [Indexed: 12/31/2022] Open
Abstract
Interactions between U2AF homology motifs (UHMs) and U2AF ligand motifs (ULMs) play a crucial role in early spliceosome assembly in eukaryotic gene regulation. UHM-ULM interactions mediate heterodimerization of the constitutive splicing factors U2AF65 and U2AF35 and between other splicing factors that regulate spliceosome assembly at the 3′ splice site, where UHM domains of alternative splicing factors, such as SPF45 and PUF60, contribute to alternative splicing regulation. Here, we performed high-throughput screening using fluorescence polarization assays with hit validation by NMR and identified phenothiazines as general inhibitors of UHM-ULM interactions. NMR studies show that these compounds occupy the tryptophan binding pocket of UHM domains. Co-crystal structures of the inhibitors with the PUF60 UHM domain and medicinal chemistry provide structure-activity-relationships and reveal functional groups important for binding. These inhibitors inhibit early spliceosome assembly on pre-mRNA substrates in vitro. Our data show that spliceosome assembly can be inhibited by targeting UHM-ULM interactions by small molecules, thus extending the toolkit of splicing modulators for structural and biochemical studies of the spliceosome and splicing regulation. So far only a few compounds have been reported as splicing modulators. Here, the authors combine high-throughput screening, chemical synthesis, NMR, X-ray crystallography with functional studies and develop phenothiazines as inhibitors for the U2AF Homology Motif (UHM) domains of proteins that regulate splicing and show that they inhibit early spliceosome assembly on pre-mRNA substrates in vitro.
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22
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Abstract
Splicing of the precursor messenger RNA, involving intron removal and exon ligation, is mediated by the spliceosome. Together with biochemical and genetic investigations of the past four decades, structural studies of the intact spliceosome at atomic resolution since 2015 have led to mechanistic delineation of RNA splicing with remarkable insights. The spliceosome is proven to be a protein-orchestrated metalloribozyme. Conserved elements of small nuclear RNA (snRNA) constitute the splicing active site with two catalytic metal ions and recognize three conserved intron elements through duplex formation, which are delivered into the splicing active site for branching and exon ligation. The protein components of the spliceosome stabilize the conformation of the snRNA, drive spliceosome remodeling, orchestrate the movement of the RNA elements, and facilitate the splicing reaction. The overall organization of the spliceosome and the configuration of the splicing active site are strictly conserved between human and yeast.
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Affiliation(s)
- Ruixue Wan
- Beijing Advanced Innovation Center for Structural Biology, School of Life Sciences and School of Medicine, Tsinghua University, Beijing 100084, China;,
| | - Rui Bai
- Institute of Biology, Westlake Institute for Advanced Study, Westlake University, Hangzhou 310024, China
| | - Xiechao Zhan
- Beijing Advanced Innovation Center for Structural Biology, School of Life Sciences and School of Medicine, Tsinghua University, Beijing 100084, China;,
| | - Yigong Shi
- Beijing Advanced Innovation Center for Structural Biology, School of Life Sciences and School of Medicine, Tsinghua University, Beijing 100084, China;,
- Institute of Biology, Westlake Institute for Advanced Study, Westlake University, Hangzhou 310024, China
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23
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Roles and mechanisms of alternative splicing in cancer - implications for care. Nat Rev Clin Oncol 2020; 17:457-474. [PMID: 32303702 DOI: 10.1038/s41571-020-0350-x] [Citation(s) in RCA: 356] [Impact Index Per Article: 89.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 03/03/2020] [Indexed: 12/14/2022]
Abstract
Removal of introns from messenger RNA precursors (pre-mRNA splicing) is an essential step for the expression of most eukaryotic genes. Alternative splicing enables the regulated generation of multiple mRNA and protein products from a single gene. Cancer cells have general as well as cancer type-specific and subtype-specific alterations in the splicing process that can have prognostic value and contribute to every hallmark of cancer progression, including cancer immune responses. These splicing alterations are often linked to the occurrence of cancer driver mutations in genes encoding either core components or regulators of the splicing machinery. Of therapeutic relevance, the transcriptomic landscape of cancer cells makes them particularly vulnerable to pharmacological inhibition of splicing. Small-molecule splicing modulators are currently in clinical trials and, in addition to splice site-switching antisense oligonucleotides, offer the promise of novel and personalized approaches to cancer treatment.
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24
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Boer RE, Torrey ZR, Schneekloth JS. Chemical Modulation of Pre-mRNA Splicing in Mammalian Systems. ACS Chem Biol 2020; 15:808-818. [PMID: 32191432 DOI: 10.1021/acschembio.0c00001] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
RNA splicing is a key component of gene expression and proteomic diversity in humans. The spliceosome assembles on and processes individual nascent pre-mRNA transcripts into distinct mature mRNAs that can code for different proteins. Splicing programs can be affected by somatic mutations and changes in response to exogenous stimuli. Importantly, alterations in splicing can be direct drivers of diseases including cancers. This Review describes recent advances and the potential for targeting and controlling pre-mRNA splicing in humans with small molecules, ranging from targeting spliceosomal proteins to direct targeting of individual RNA transcripts.
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Affiliation(s)
- Robert E. Boer
- Chemical Biology Laboratory, National Cancer Institute, Frederick Maryland 21702, United States
| | - Zachary R. Torrey
- Chemical Biology Laboratory, National Cancer Institute, Frederick Maryland 21702, United States
| | - John S. Schneekloth
- Chemical Biology Laboratory, National Cancer Institute, Frederick Maryland 21702, United States
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Desterro J, Bak-Gordon P, Carmo-Fonseca M. Targeting mRNA processing as an anticancer strategy. Nat Rev Drug Discov 2019; 19:112-129. [PMID: 31554928 DOI: 10.1038/s41573-019-0042-3] [Citation(s) in RCA: 107] [Impact Index Per Article: 21.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 08/08/2019] [Indexed: 12/19/2022]
Abstract
Discoveries in the past decade have highlighted the potential of mRNA as a therapeutic target for cancer. Specifically, RNA sequencing revealed that, in addition to gene mutations, alterations in mRNA can contribute to the initiation and progression of cancer. Indeed, precursor mRNA processing, which includes the removal of introns by splicing and the formation of 3' ends by cleavage and polyadenylation, is frequently altered in tumours. These alterations result in numerous cancer-specific mRNAs that generate altered levels of normal proteins or proteins with new functions, leading to the activation of oncogenes or the inactivation of tumour-suppressor genes. Abnormally spliced and polyadenylated mRNAs are also associated with resistance to cancer treatment and, unexpectedly, certain cancers are highly sensitive to the pharmacological inhibition of splicing. This Review summarizes recent progress in our understanding of how splicing and polyadenylation are altered in cancer and highlights how this knowledge has been translated for drug discovery, resulting in the production of small molecules and oligonucleotides that modulate the spliceosome and are in clinical trials for the treatment of cancer.
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Affiliation(s)
- Joana Desterro
- Instituto de Medicina Molecular João Lobo Antunes, Faculdade de Medicina, Universidade de Lisboa, Lisboa, Portugal.,Instituto Português de Oncologia de Lisboa, Serviço de Hematologia, Lisboa, Portugal
| | - Pedro Bak-Gordon
- Instituto de Medicina Molecular João Lobo Antunes, Faculdade de Medicina, Universidade de Lisboa, Lisboa, Portugal
| | - Maria Carmo-Fonseca
- Instituto de Medicina Molecular João Lobo Antunes, Faculdade de Medicina, Universidade de Lisboa, Lisboa, Portugal.
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26
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Andrews RJ, Moss WN. Computational approaches for the discovery of splicing regulatory RNA structures. BIOCHIMICA ET BIOPHYSICA ACTA-GENE REGULATORY MECHANISMS 2019; 1862:194380. [PMID: 31048028 DOI: 10.1016/j.bbagrm.2019.04.007] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/26/2019] [Revised: 04/15/2019] [Accepted: 04/16/2019] [Indexed: 12/14/2022]
Abstract
Global RNA structure and local functional motifs mediate interactions important in determining the rates and patterns of mRNA splicing. In this review, we overview approaches for the computational prediction of RNA secondary structure with a special emphasis on the discovery of motifs important to RNA splicing. The process of identifying and modeling potential splicing regulatory structures is illustrated using a recently-developed approach for RNA structural motif discovery, the ScanFold pipeline, which is applied to the identification of a known splicing regulatory structure in influenza virus.
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Affiliation(s)
- Ryan J Andrews
- Roy J. Carver Department of Biochemistry, Biophysics, and Molecular Biology, Iowa State University, 2437 Pammel Drive, Ames, IA 50011, USA
| | - Walter N Moss
- Roy J. Carver Department of Biochemistry, Biophysics, and Molecular Biology, Iowa State University, 2437 Pammel Drive, Ames, IA 50011, USA.
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27
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DeNicola AB, Tang Y. Therapeutic approaches to treat human spliceosomal diseases. Curr Opin Biotechnol 2019; 60:72-81. [PMID: 30772756 DOI: 10.1016/j.copbio.2019.01.003] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/03/2018] [Accepted: 01/02/2019] [Indexed: 02/06/2023]
Abstract
Mutated RNA splicing machinery drives many human diseases and is a promising therapeutic target for engineering and small molecule therapy. In the case of mutations in individual genes that cause them to be incorrectly spliced, engineered splicing factors can be introduced to correct splicing of these aberrant transcripts and reduce the effects of the disease phenotype. Mutations that occur in certain splicing factor genes themselves have been implicated in many cancers, particularly myelodysplastic syndromes. Small molecules that target splicing factors have been developed as therapies to preferentially induce apoptosis in these cancer cells. Specifically, drugs targeting the splicing factor SF3B1 have led to recent clinical trials. Here, we review the role of alternative splicing in disease, approaches to rescue incorrect splicing using engineered splicing factors, and small molecule splicing inhibitors developed to treat hematological cancers.
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Affiliation(s)
- Anthony B DeNicola
- Department of Chemical and Biomolecular Engineering, University of California, Los Angeles, CA 90095, United States.
| | - Yi Tang
- Department of Chemical and Biomolecular Engineering, University of California, Los Angeles, CA 90095, United States
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28
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Yan C, Wan R, Shi Y. Molecular Mechanisms of pre-mRNA Splicing through Structural Biology of the Spliceosome. Cold Spring Harb Perspect Biol 2019; 11:11/1/a032409. [PMID: 30602541 DOI: 10.1101/cshperspect.a032409] [Citation(s) in RCA: 88] [Impact Index Per Article: 17.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
Precursor messenger RNA (pre-mRNA) splicing is executed by the spliceosome. In the past 3 years, cryoelectron microscopy (cryo-EM) structures have been elucidated for a majority of the yeast spliceosomal complexes and for a few human spliceosomes. During the splicing reaction, the dynamic spliceosome has an immobile core of about 20 protein and RNA components, which are organized around a conserved splicing active site. The divalent metal ions, coordinated by U6 small nuclear RNA (snRNA), catalyze the branching reaction and exon ligation. The spliceosome also contains a mobile but compositionally stable group of about 13 proteins and a portion of U2 snRNA, which facilitate substrate delivery into the splicing active site. The spliceosomal transitions are driven by the RNA-dependent ATPase/helicases, resulting in the recruitment and dissociation of specific splicing factors that enable the reaction. In summary, the spliceosome is a protein-directed metalloribozyme.
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Affiliation(s)
- Chuangye Yan
- Beijing Advanced Innovation Center for Structural Biology, School of Life Sciences, Tsinghua University, Beijing 100084, China
| | - Ruixue Wan
- Beijing Advanced Innovation Center for Structural Biology, School of Life Sciences, Tsinghua University, Beijing 100084, China
| | - Yigong Shi
- Beijing Advanced Innovation Center for Structural Biology, School of Life Sciences, Tsinghua University, Beijing 100084, China.,Institute of Biology, Westlake Institute for Advanced Study, Westlake University, Hangzhou 310064, Zhejiang Province, China
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Olender J, Lee NH. Role of Alternative Splicing in Prostate Cancer Aggressiveness and Drug Resistance in African Americans. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2019; 1164:119-139. [PMID: 31576545 PMCID: PMC6777849 DOI: 10.1007/978-3-030-22254-3_10] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
Alternative splicing, the process of removing introns and joining exons of pre-mRNA, is critical for growth, development, tissue homeostasis, and species diversity. Dysregulation of alternative splicing can initiate and drive disease. Aberrant alternative splicing has been shown to promote the "hallmarks of cancer" in both hematological and solid cancers. Of interest, recent work has focused on the role of alternative splicing in prostate cancer and prostate cancer health disparities. We will provide a review of prostate cancer health disparities involving the African American population, alternative RNA splicing, and alternative splicing in prostate cancer. Lastly, we will summarize our work on differential alternative splicing in prostate cancer disparities and its implications for disparate health outcomes and therapeutic targets.
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Affiliation(s)
- Jacqueline Olender
- Department of Pharmacology and Physiology, GW Cancer Center, George Washington University School of Medicine and Health Sciences, Washington, DC, USA
| | - Norman H Lee
- Department of Pharmacology and Physiology, GW Cancer Center, George Washington University School of Medicine and Health Sciences, Washington, DC, USA.
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Ghosh AK, Reddy GC, Kovela S, Relitti N, Urabe VK, Prichard BE, Jurica MS. Enantioselective Synthesis of a Cyclopropane Derivative of Spliceostatin A and Evaluation of Bioactivity. Org Lett 2018; 20:7293-7297. [PMID: 30394756 PMCID: PMC6519444 DOI: 10.1021/acs.orglett.8b03228] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
Spliceostatin A is a potent inhibitor of spliceosomes and exhibits excellent anticancer activity against multiple human cancer cell lines. We describe here the design and synthesis of a stable cyclopropane derivative of spliceostatin A. The synthesis involved a cross-metathesis or a Suzuki cross-coupling reaction as the key step. The functionalized epoxy alcohol ring was constructed from commercially available optically active tri- O-acetyl-d-glucal. The biological properties of the cyclopropyl derivative revealed that it is active in human cells and inhibits splicing in vitro comparable to spliceostatin A.
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Affiliation(s)
- Arun K Ghosh
- Department of Chemistry and Department of Medicinal Chemistry , Purdue University , 560 Oval Drive , West Lafayette , Indiana 47907 , United States
| | - Guddeti Chandrashekar Reddy
- Department of Chemistry and Department of Medicinal Chemistry , Purdue University , 560 Oval Drive , West Lafayette , Indiana 47907 , United States
| | - Satish Kovela
- Department of Chemistry and Department of Medicinal Chemistry , Purdue University , 560 Oval Drive , West Lafayette , Indiana 47907 , United States
| | - Nicola Relitti
- Department of Chemistry and Department of Medicinal Chemistry , Purdue University , 560 Oval Drive , West Lafayette , Indiana 47907 , United States
| | - Veronica K Urabe
- Department of Molecular Cell and Developmental Biology and Center for Molecular Biology of RNA , University of California , Santa Cruz , California 95064 , United States
| | - Beth E Prichard
- Department of Molecular Cell and Developmental Biology and Center for Molecular Biology of RNA , University of California , Santa Cruz , California 95064 , United States
| | - Melissa S Jurica
- Department of Molecular Cell and Developmental Biology and Center for Molecular Biology of RNA , University of California , Santa Cruz , California 95064 , United States
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Targeting the spliceosome for cutaneous squamous cell carcinoma therapy: a role for c-MYC and wild-type p53 in determining the degree of tumour selectivity. Oncotarget 2018; 9:23029-23046. [PMID: 29796170 PMCID: PMC5955416 DOI: 10.18632/oncotarget.25196] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/09/2017] [Accepted: 04/04/2018] [Indexed: 12/25/2022] Open
Abstract
We show that suppression of the spliceosome has potential for the treatment of cutaneous squamous cell carcinoma (cSCC). The small-molecule inhibitors of the spliceosome at the most advanced stage of development target the splicing factor SF3B1/SF3b155. The majority of cSCC cell lines are more sensitive than normal skin cells to death induced by the SF3B1 inhibitor pladienolide B. Knockdown of SF3B1 and a range of other splicing factors with diverse roles in the spliceosome can also selectively kill cSCC cells. We demonstrate that endogenous c-MYC participates in conferring sensitivity to spliceosome inhibition. c-MYC expression is elevated in cSCC lines and its knockdown reduces alterations in mRNA splicing and attenuates cell death caused by interference with the spliceosome. In addition, this study provides further support for a key role of the p53 pathway in the response to spliceosome disruption. SF3B1 inhibition causes wild-type p53 upregulation associated with altered mRNA splicing and reduced protein expression of both principal p53 negative regulators MDMX/MDM4 and MDM2. We observed that wild-type p53 can promote pladienolide B-induced death in tumour cells. However, p53 is commonly inactivated by mutation in cSCCs and p53 participates in killing normal skin cells at high concentrations of pladienolide B. This may limit the therapeutic window of SF3B1 inhibitors for cSCC. We provide evidence that, while suppression of SF3B1 has promise for treating cSCCs with mutant p53, inhibitors which target the spliceosome through SF3B1-independent mechanisms could have greater cSCC selectivity as a consequence of reduced p53 upregulation in normal cells.
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Ray S, Widom JR, Walter NG. Life under the Microscope: Single-Molecule Fluorescence Highlights the RNA World. Chem Rev 2018; 118:4120-4155. [PMID: 29363314 PMCID: PMC5918467 DOI: 10.1021/acs.chemrev.7b00519] [Citation(s) in RCA: 40] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
The emergence of single-molecule (SM) fluorescence techniques has opened up a vast new toolbox for exploring the molecular basis of life. The ability to monitor individual biomolecules in real time enables complex, dynamic folding pathways to be interrogated without the averaging effect of ensemble measurements. In parallel, modern biology has been revolutionized by our emerging understanding of the many functions of RNA. In this comprehensive review, we survey SM fluorescence approaches and discuss how the application of these tools to RNA and RNA-containing macromolecular complexes in vitro has yielded significant insights into the underlying biology. Topics covered include the three-dimensional folding landscapes of a plethora of isolated RNA molecules, their assembly and interactions in RNA-protein complexes, and the relation of these properties to their biological functions. In all of these examples, the use of SM fluorescence methods has revealed critical information beyond the reach of ensemble averages.
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Affiliation(s)
| | | | - Nils G. Walter
- Department of Chemistry, Single Molecule Analysis Group, University of Michigan, Ann Arbor, MI 48109, USA
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Didychuk AL, Butcher SE, Brow DA. The life of U6 small nuclear RNA, from cradle to grave. RNA (NEW YORK, N.Y.) 2018; 24:437-460. [PMID: 29367453 PMCID: PMC5855946 DOI: 10.1261/rna.065136.117] [Citation(s) in RCA: 67] [Impact Index Per Article: 11.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/04/2023]
Abstract
Removal of introns from precursor messenger RNA (pre-mRNA) and some noncoding transcripts is an essential step in eukaryotic gene expression. In the nucleus, this process of RNA splicing is carried out by the spliceosome, a multi-megaDalton macromolecular machine whose core components are conserved from yeast to humans. In addition to many proteins, the spliceosome contains five uridine-rich small nuclear RNAs (snRNAs) that undergo an elaborate series of conformational changes to correctly recognize the splice sites and catalyze intron removal. Decades of biochemical and genetic data, along with recent cryo-EM structures, unequivocally demonstrate that U6 snRNA forms much of the catalytic core of the spliceosome and is highly dynamic, interacting with three snRNAs, the pre-mRNA substrate, and >25 protein partners throughout the splicing cycle. This review summarizes the current state of knowledge on how U6 snRNA is synthesized, modified, incorporated into snRNPs and spliceosomes, recycled, and degraded.
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Affiliation(s)
- Allison L Didychuk
- Department of Biochemistry, University of Wisconsin, Madison, Wisconsin 53706, USA
| | - Samuel E Butcher
- Department of Biochemistry, University of Wisconsin, Madison, Wisconsin 53706, USA
| | - David A Brow
- Department of Biomolecular Chemistry, School of Medicine and Public Health, University of Wisconsin, Madison, Wisconsin 53706, USA
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Rambout X, Dequiedt F, Maquat LE. Beyond Transcription: Roles of Transcription Factors in Pre-mRNA Splicing. Chem Rev 2017; 118:4339-4364. [PMID: 29251915 DOI: 10.1021/acs.chemrev.7b00470] [Citation(s) in RCA: 42] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Abstract
Whereas individual steps of protein-coding gene expression in eukaryotes can be studied in isolation in vitro, it has become clear that these steps are intimately connected within cells. Connections not only ensure quality control but also fine-tune the gene expression process, which must adapt to environmental changes while remaining robust. In this review, we systematically present proven and potential mechanisms by which sequence-specific DNA-binding transcription factors can alter gene expression beyond transcription initiation and regulate pre-mRNA splicing, and thereby mRNA isoform production, by (i) influencing transcription elongation rates, (ii) binding to pre-mRNA to recruit splicing factors, and/or (iii) blocking the association of splicing factors with pre-mRNA. We propose various mechanistic models throughout the review, in some cases without explicit supportive evidence, in hopes of providing fertile ground for future studies.
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León B, Kashyap MK, Chan WC, Krug KA, Castro JE, La Clair JJ, Burkart MD. A Challenging Pie to Splice: Drugging the Spliceosome. Angew Chem Int Ed Engl 2017; 56:12052-12063. [PMID: 28371109 PMCID: PMC6311392 DOI: 10.1002/anie.201701065] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/30/2017] [Indexed: 02/05/2023]
Abstract
Since its discovery in 1977, the study of alternative RNA splicing has revealed a plethora of mechanisms that had never before been documented in nature. Understanding these transitions and their outcome at the level of the cell and organism has become one of the great frontiers of modern chemical biology. Until 2007, this field remained in the hands of RNA biologists. However, the recent identification of natural product and synthetic modulators of RNA splicing has opened new access to this field, allowing for the first time a chemical-based interrogation of RNA splicing processes. Simultaneously, we have begun to understand the vital importance of splicing in disease, which offers a new platform for molecular discovery and therapy. As with many natural systems, gaining clear mechanistic detail at the molecular level is key towards understanding the operation of any biological machine. This minireview presents recent lessons learned in this emerging field of RNA splicing chemistry and chemical biology.
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Affiliation(s)
- Brian León
- Department of Chemistry and Biochemistry, University of California, San Diego 9500, Gilman Drive, La Jolla CA, 92093-0358 (USA) ,
| | - Manoj K. Kashyap
- Moores Cancer Center and Department of Medicine, University of California, San Diego, La Jolla CA, 92093-0820 (USA)
| | - Warren C. Chan
- Department of Chemistry and Biochemistry, University of California, San Diego 9500, Gilman Drive, La Jolla CA, 92093-0358 (USA) ,
| | - Kelsey A. Krug
- Department of Chemistry and Biochemistry, University of California, San Diego 9500, Gilman Drive, La Jolla CA, 92093-0358 (USA) ,
| | - Januario E. Castro
- Moores Cancer Center and Department of Medicine, University of California, San Diego, La Jolla CA, 92093-0820 (USA)
| | - James J. La Clair
- Department of Chemistry and Biochemistry, University of California, San Diego 9500, Gilman Drive, La Jolla CA, 92093-0358 (USA) ,
| | - Michael D. Burkart
- Department of Chemistry and Biochemistry, University of California, San Diego 9500, Gilman Drive, La Jolla CA, 92093-0358 (USA) ,
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León B, Kashyap MK, Chan WC, Krug KA, Castro JE, La Clair JJ, Burkart MD. Das Spliceosom als Angriffspunkt für Pharmaka. Angew Chem Int Ed Engl 2017. [DOI: 10.1002/ange.201701065] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Affiliation(s)
- Brian León
- Department of Chemistry and Biochemistry; University of California, San Diego; 9500 Gilman Drive La Jolla CA 92093-0358 USA
| | - Manoj K. Kashyap
- Moores Cancer Center and Department of Medicine; University of California, San Diego; La Jolla CA 92093-0820 USA
| | - Warren C. Chan
- Department of Chemistry and Biochemistry; University of California, San Diego; 9500 Gilman Drive La Jolla CA 92093-0358 USA
| | - Kelsey A. Krug
- Department of Chemistry and Biochemistry; University of California, San Diego; 9500 Gilman Drive La Jolla CA 92093-0358 USA
| | - Januario E. Castro
- Moores Cancer Center and Department of Medicine; University of California, San Diego; La Jolla CA 92093-0820 USA
| | - James J. La Clair
- Department of Chemistry and Biochemistry; University of California, San Diego; 9500 Gilman Drive La Jolla CA 92093-0358 USA
| | - Michael D. Burkart
- Department of Chemistry and Biochemistry; University of California, San Diego; 9500 Gilman Drive La Jolla CA 92093-0358 USA
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Cryo-EM Structure of a Pre-catalytic Human Spliceosome Primed for Activation. Cell 2017; 170:701-713.e11. [DOI: 10.1016/j.cell.2017.07.011] [Citation(s) in RCA: 170] [Impact Index Per Article: 24.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/14/2017] [Revised: 06/22/2017] [Accepted: 07/11/2017] [Indexed: 11/19/2022]
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