1
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Seyhan AA. Circulating microRNAs as Potential Biomarkers in Pancreatic Cancer-Advances and Challenges. Int J Mol Sci 2023; 24:13340. [PMID: 37686149 PMCID: PMC10488102 DOI: 10.3390/ijms241713340] [Citation(s) in RCA: 9] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/05/2023] [Revised: 08/21/2023] [Accepted: 08/25/2023] [Indexed: 09/10/2023] Open
Abstract
There is an urgent unmet need for robust and reliable biomarkers for early diagnosis, prognosis, and prediction of response to specific treatments of many aggressive and deadly cancers, such as pancreatic cancer, and liquid biopsy-based miRNA profiling has the potential for this. MiRNAs are a subset of non-coding RNAs that regulate the expression of a multitude of genes post-transcriptionally and thus are potential diagnostic, prognostic, and predictive biomarkers and have also emerged as potential therapeutics. Because miRNAs are involved in the post-transcriptional regulation of their target mRNAs via repressing gene expression, defects in miRNA biogenesis pathway and miRNA expression perturb the expression of a multitude of oncogenic or tumor-suppressive genes that are involved in the pathogenesis of various cancers. As such, numerous miRNAs have been identified to be downregulated or upregulated in many cancers, functioning as either oncomes or oncosuppressor miRs. Moreover, dysregulation of miRNA biogenesis pathways can also change miRNA expression and function in cancer. Profiling of dysregulated miRNAs in pancreatic cancer has been shown to correlate with disease diagnosis, indicate optimal treatment options and predict response to a specific therapy. Specific miRNA signatures can track the stages of pancreatic cancer and hold potential as diagnostic, prognostic, and predictive markers, as well as therapeutics such as miRNA mimics and miRNA inhibitors (antagomirs). Furthermore, identified specific miRNAs and genes they regulate in pancreatic cancer along with downstream pathways can be used as potential therapeutic targets. However, a limited understanding and validation of the specific roles of miRNAs, lack of tissue specificity, methodological, technical, or analytical reproducibility, harmonization of miRNA isolation and quantification methods, the use of standard operating procedures, and the availability of automated and standardized assays to improve reproducibility between independent studies limit bench-to-bedside translation of the miRNA biomarkers for clinical applications. Here I review recent findings on miRNAs in pancreatic cancer pathogenesis and their potential as diagnostic, prognostic, and predictive markers.
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Affiliation(s)
- Attila A. Seyhan
- Laboratory of Translational Oncology and Experimental Cancer Therapeutics, Warren Alpert Medical School, Brown University, Providence, RI 02912, USA;
- Department of Pathology and Laboratory Medicine, Warren Alpert Medical School, Brown University, Providence, RI 02912, USA
- Joint Program in Cancer Biology, Lifespan Health System and Brown University, Providence, RI 02912, USA
- Legorreta Cancer Center, Brown University, Providence, RI 02912, USA
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2
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Bortoletto AS, Parchem RJ. KRAS Hijacks the miRNA Regulatory Pathway in Cancer. Cancer Res 2023; 83:1563-1572. [PMID: 36946612 PMCID: PMC10183808 DOI: 10.1158/0008-5472.can-23-0296] [Citation(s) in RCA: 8] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/27/2023] [Revised: 03/01/2023] [Accepted: 03/20/2023] [Indexed: 03/23/2023]
Abstract
Extensive studies have focused on the misregulation of individual miRNAs in cancer. More recently, mutations in the miRNA biogenesis and processing machinery have been implicated in several malignancies. Such mutations can lead to global miRNA misregulation, which may promote many of the well-known hallmarks of cancer. Interestingly, recent evidence also suggests that oncogenic Kristen rat sarcoma viral oncogene homolog (KRAS) mutations act in part by modulating the activity of members of the miRNA regulatory pathway. Here, we highlight the vital role mutations in the miRNA core machinery play in promoting malignant transformation. Furthermore, we discuss how mutant KRAS can simultaneously impact multiple steps of miRNA processing and function to promote tumorigenesis. Although the ability of KRAS to hijack the miRNA regulatory pathway adds a layer of complexity to its oncogenic nature, it also provides a potential therapeutic avenue that has yet to be exploited in the clinic. Moreover, concurrent targeting of mutant KRAS and members of the miRNA core machinery represents a potential strategy for treating cancer.
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Affiliation(s)
- Angelina S. Bortoletto
- Center for Cell and Gene Therapy, Stem Cell and Regenerative Medicine Center, Department of Molecular and Cellular Biology, Department of Neuroscience, Translational Biology and Molecular Medicine Program, Medical Scientist Training Program, Baylor College of Medicine, Houston, Texas
| | - Ronald J. Parchem
- Center for Cell and Gene Therapy, Stem Cell and Regenerative Medicine Center, Department of Molecular and Cellular Biology, Department of Neuroscience, Translational Biology and Molecular Medicine Program, Medical Scientist Training Program, Baylor College of Medicine, Houston, Texas
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3
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Zhang Y, Kang JY, Liu M, Huang Y. Diverse roles of biomolecular condensation in eukaryotic translational regulation. RNA Biol 2023; 20:893-907. [PMID: 37906632 PMCID: PMC10730148 DOI: 10.1080/15476286.2023.2275108] [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] [Accepted: 10/20/2023] [Indexed: 11/02/2023] Open
Abstract
Biomolecular condensates, forming membrane-less organelles, orchestrate the sub-cellular compartment to execute designated biological processes. An increasing body of evidence demonstrates the involvement of these biomolecular condensates in translational regulation. This review summarizes recent discoveries concerning biomolecular condensates associated with translational regulation, including their composition, assembly, and functions. Furthermore, we discussed the common features among these biomolecular condensates and the critical questions in the translational regulation areas. These emerging discoveries shed light on the enigmatic translational machinery, refine our understanding of translational regulation, and put forth potential therapeutic targets for diseases born out of translation dysregulation.
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Grants
- 32171186 AND 91940302 National Natural Science Foundation of China
- 91940305, 31830109, 31821004, 31961133022, 91640201, 32170815, AND 32101037 TO M.L., AND 32201058 National Natural Science Foundation of China
- 2022YFC2702600 National Key R&D Program of China
- 17JC1420100, 2017SHZDZX01, 19JC1410200, 21ZR1470200, 21PJ1413800, 21YF1452700, AND 21ZR1470500 Science and Technology Commission of Shanghai Municipality
- 2022YFC2702600 National Key R&D Program of China
- 2022T150425 China Postdoctoral Science Foundation
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Affiliation(s)
- Yuhan Zhang
- Department of General Surgery, Shanghai Key Laboratory of Biliary Tract Disease Research, State Key Laboratory of Oncogenes and Related Genes, Xinhua Hospital, Shanghai Jiao Tong University, Shanghai, China
| | - Jun-Yan Kang
- Department of Ophthalmology, Shanghai Key Laboratory of Orbital Diseases and Ocular Oncology, Shanghai Ninth People’s Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai, China
| | - Mofang Liu
- State Key Laboratory of Molecular Biology, State Key Laboratory of Cell Biology, Shanghai Key Laboratory of Molecular Andrology, Shanghai Institute of Biochemistry and Cell Biology, Center for Excellence in Molecular Cell Science, Chinese Academy of Sciences, University of Chinese Academy of Sciences, Shanghai, China
| | - Ying Huang
- Department of General Surgery, Shanghai Key Laboratory of Biliary Tract Disease Research, State Key Laboratory of Oncogenes and Related Genes, Xinhua Hospital, Shanghai Jiao Tong University, Shanghai, China
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4
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Hurst Z, Liu W, Shi Q, Herman PK. A distinct P-body-like granule is induced in response to the disruption of microtubule integrity in Saccharomyces cerevisiae. Genetics 2022; 222:6649695. [PMID: 35876801 PMCID: PMC9434292 DOI: 10.1093/genetics/iyac105] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/09/2022] [Accepted: 07/08/2022] [Indexed: 11/12/2022] Open
Abstract
The Processing-body (P-body) is a conserved membraneless organelle that has been implicated in the storage and/or decay of mRNAs. Although P-bodies have been shown to be induced by a variety of conditions, the mechanisms controlling their assembly and their precise physiological roles in eukaryotic cells are still being worked out. In this study, we find that a distinct subtype of P-body is induced in response to conditions that disrupt microtubule integrity in the budding yeast, Saccharomyces cerevisiae. For example, treatment with the microtubule-destabilizing agent, benomyl, led to the induction of these novel ribonucleoprotein (RNP) granules. A link to microtubules had been noted previously and the observations here extend our understanding by demonstrating that the induced foci differ from traditional P-bodies in a number of significant ways. These include differences in overall granule morphology, protein composition and the manner in which their induction is regulated. Of particular note, several key P-body constituents are absent from these Benomyl-Induced Granules (BIGs), including the Pat1 protein that is normally required for efficient P-body assembly. However, these novel RNP structures still contain many known P-body proteins and exhibit similar hallmarks of a liquid-like compartment. In all, the data suggest that the disruption of microtubule integrity leads to the formation of a novel type of P-body granule that may have distinct biological activities in the cell. Future work will aim to identify the biological activities of these BIGs and to determine, in turn, whether these P-body-like granules have any role in the regulation of microtubule dynamics.
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Affiliation(s)
- Zachary Hurst
- Department of Molecular Genetics, Ohio State University, Columbus, Ohio 43210 USA
| | - Wenfang Liu
- Department of Molecular Genetics, Ohio State University, Columbus, Ohio 43210 USA
| | - Qian Shi
- Department of Molecular Genetics, Ohio State University, Columbus, Ohio 43210 USA
| | - Paul K Herman
- Department of Molecular Genetics, Ohio State University, Columbus, Ohio 43210 USA
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5
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Shah A, Bhandari R. IP6K1 upregulates the formation of processing bodies by influencing protein-protein interactions on the mRNA cap. J Cell Sci 2021; 134:273758. [PMID: 34841428 DOI: 10.1242/jcs.259117] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/14/2021] [Accepted: 11/11/2021] [Indexed: 11/20/2022] Open
Abstract
Inositol hexakisphosphate kinase 1 (IP6K1) is a small molecule kinase that catalyzes the conversion of the inositol phosphate IP6 to 5-IP7. We show that IP6K1 acts independently of its catalytic activity to upregulate the formation of processing bodies (P-bodies), which are cytoplasmic ribonucleoprotein granules that store translationally repressed mRNA. IP6K1 does not localise to P-bodies, but instead binds to ribosomes, where it interacts with the mRNA decapping complex - the scaffold protein EDC4, activator proteins DCP1A/B, decapping enzyme DCP2 and RNA helicase DDX6. Along with its partner 4E-T, DDX6 is known to nucleate protein-protein interactions on the 5' mRNA cap to facilitate P-body formation. IP6K1 binds the translation initiation complex eIF4F on the mRNA cap, augmenting the interaction of DDX6 with 4E-T (also known as EIF4ENIF1) and the cap-binding protein eIF4E. Cells with reduced IP6K1 show downregulated microRNA-mediated translational suppression and increased stability of DCP2-regulated transcripts. Our findings unveil IP6K1 as a novel facilitator of proteome remodelling on the mRNA cap, tipping the balance in favour of translational repression over initiation, thus leading to P-body assembly. This article has an associated First Person interview with the first author of the paper.
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Affiliation(s)
- Akruti Shah
- Laboratory of Cell Signalling, Centre for DNA Fingerprinting and Diagnostics (CDFD), Inner Ring Road, Uppal, Hyderabad 500039, India.,Graduate Studies, Manipal Academy of Higher Education, Manipal 576104, India
| | - Rashna Bhandari
- Laboratory of Cell Signalling, Centre for DNA Fingerprinting and Diagnostics (CDFD), Inner Ring Road, Uppal, Hyderabad 500039, India
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6
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Mamon L, Yakimova A, Kopytova D, Golubkova E. The RNA-Binding Protein SBR (Dm NXF1) Is Required for the Constitution of Medulla Boundaries in Drosophila melanogaster Optic Lobes. Cells 2021; 10:1144. [PMID: 34068524 PMCID: PMC8151460 DOI: 10.3390/cells10051144] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/18/2021] [Revised: 05/05/2021] [Accepted: 05/06/2021] [Indexed: 11/17/2022] Open
Abstract
Drosophila melanogaster sbr (small bristles) is an orthologue of the Nxf1 (nuclear export factor 1) genes in different Opisthokonta. The known function of Nxf1 genes is the export of various mRNAs from the nucleus to the cytoplasm. The cytoplasmic localization of the SBR protein indicates that the nuclear export function is not the only function of this gene in Drosophila. RNA-binding protein SBR enriches the nucleus and cytoplasm of specific neurons and glial cells. In sbr12 mutant males, the disturbance of medulla boundaries correlates with the defects of photoreceptor axons pathfinding, axon bundle individualization, and developmental neurodegeneration. RNA-binding protein SBR participates in processes allowing axons to reach and identify their targets.
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Affiliation(s)
- Ludmila Mamon
- Department of Genetics and Biotechnology, Saint-Petersburg State University, Universitetskaya Emb. 7/9, 199034 St. Petersburg, Russia; or
| | - Anna Yakimova
- A. Tsyb Medical Radiological Research Center—Branch of the National Medical Research Radiological Center of the Ministry of Health of the Russian Federation, Koroleva Str. 4, 249036 Obninsk, Russia;
| | - Daria Kopytova
- Institute of Gene Biology, Russian Academy of Sciences, Vavilov St. 34/5, 119334 Moscow, Russia;
| | - Elena Golubkova
- Department of Genetics and Biotechnology, Saint-Petersburg State University, Universitetskaya Emb. 7/9, 199034 St. Petersburg, Russia; or
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7
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Escalante LE, Gasch AP. The role of stress-activated RNA-protein granules in surviving adversity. RNA (NEW YORK, N.Y.) 2021; 27:rna.078738.121. [PMID: 33931500 PMCID: PMC8208049 DOI: 10.1261/rna.078738.121] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/04/2021] [Accepted: 04/28/2021] [Indexed: 05/17/2023]
Abstract
Severe environmental stress can trigger a plethora of physiological changes and, in the process, significant cytoplasmic reorganization. Stress-activated RNA-protein granules have been implicated in this cellular overhaul by sequestering pre-existing mRNAs and influencing their fates during and after stress acclimation. While the composition and dynamics of stress-activated granule formation has been well studied, their function and impact on RNA-cargo has remained murky. Several recent studies challenge the view that these granules degrade and silence mRNAs present at the onset of stress and instead suggest new roles for these structures in mRNA storage, transit, and inheritance. Here we discuss recent evidence for revised models of stress-activated granule functions and the role of these granules in stress survival and recovery.
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8
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Barraza CE, Solari CA, Rinaldi J, Ojeda L, Rossi S, Ashe MP, Portela P. A prion-like domain of Tpk2 catalytic subunit of protein kinase A modulates P-body formation in response to stress in budding yeast. BIOCHIMICA ET BIOPHYSICA ACTA. MOLECULAR CELL RESEARCH 2021; 1868:118884. [PMID: 33039554 DOI: 10.1016/j.bbamcr.2020.118884] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/06/2020] [Revised: 09/26/2020] [Accepted: 09/29/2020] [Indexed: 01/19/2023]
Abstract
Low complexity regions are involved in the assembly and disassembly of P-bodies (PBs). Saccharomyces cerevisiae contains three genes encoding the protein kinase A (PKA) catalytic subunit: TPK1, TPK2 and TPK3. Tpk2 and Tpk3 isoforms localize to PBs upon glucose starvation showing different mechanisms and kinetics of accumulation. In contrast to the other two isoforms, Tpk2 harbors a glutamine-rich prion-like domain (PrLD) at the N-terminus. Here we show that the appearance of Tpk2 foci in response to glucose starvation, heat stress or stationary phase was dependent on its PrLD. Moreover, the PrLD of Tpk2 was necessary for efficient PB and stress granule aggregation during stress conditions and in quiescent cells. Deletion of PrLD does not affect the in vitro and in vivo kinase activity of Tpk2 or its interaction with the regulatory subunit Bcy1. We present evidence that the PrLD of Tpk2 serves as a scaffold domain for PB assembly in a manner that is independent of Pat1 phosphorylation by PKA. In addition, a mutant strain where Tpk2 lacks PrLD showed a decrease of turnover of mRNA during glucose starvation. This work therefore provides new insight into the mechanism of stress-induced cytoplasmic mRNP assembly, and the role of isoform specific domains in the regulation of PKA catalytic subunit specificity and dynamic localization to cytoplasmic RNPs granules.
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Affiliation(s)
- Carla E Barraza
- Universidad de Buenos Aires, Facultad de Ciencias Exactas y Naturales, Departamento de Química Biológica, Instituto de Química Biológica de la Facultad de Ciencias Exactas y Naturales-Consejo Nacional de Investigaciones Científicas y Técnicas (IQUIBICEN-CONICET). Buenos Aires, Argentina.
| | - Clara A Solari
- Universidad de Buenos Aires, Facultad de Ciencias Exactas y Naturales, Departamento de Química Biológica, Instituto de Química Biológica de la Facultad de Ciencias Exactas y Naturales-Consejo Nacional de Investigaciones Científicas y Técnicas (IQUIBICEN-CONICET). Buenos Aires, Argentina.
| | - Jimena Rinaldi
- Fundación Instituto Leloir, IIBBA-CONICET, Buenos Aires, Argentina.
| | - Lucas Ojeda
- Universidad de Buenos Aires, Facultad de Ciencias Exactas y Naturales, Departamento de Química Biológica, Instituto de Química Biológica de la Facultad de Ciencias Exactas y Naturales-Consejo Nacional de Investigaciones Científicas y Técnicas (IQUIBICEN-CONICET). Buenos Aires, Argentina.
| | - Silvia Rossi
- Universidad de Buenos Aires, Facultad de Ciencias Exactas y Naturales, Departamento de Química Biológica, Instituto de Química Biológica de la Facultad de Ciencias Exactas y Naturales-Consejo Nacional de Investigaciones Científicas y Técnicas (IQUIBICEN-CONICET). Buenos Aires, Argentina.
| | - Mark P Ashe
- The Michael Smith Building, Faculty of Life Sciences, University of Manchester, Manchester, UK.
| | - Paula Portela
- Universidad de Buenos Aires, Facultad de Ciencias Exactas y Naturales, Departamento de Química Biológica, Instituto de Química Biológica de la Facultad de Ciencias Exactas y Naturales-Consejo Nacional de Investigaciones Científicas y Técnicas (IQUIBICEN-CONICET). Buenos Aires, Argentina.
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9
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Kanakamani S, Suresh PS, Venkatesh T. Regulation of processing bodies: From viruses to cancer epigenetic machinery. Cell Biol Int 2020; 45:708-719. [PMID: 33325125 DOI: 10.1002/cbin.11527] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/21/2020] [Revised: 10/17/2020] [Accepted: 12/13/2020] [Indexed: 11/08/2022]
Abstract
Processing bodies (PBs) are 100-300 nm cytoplasmic messenger ribonucleoprotein particle (mRNP) granules that regulate eukaryotic gene expression. These cytoplasmic compartments harbor messenger RNAs (mRNAs) and several proteins involved in mRNA decay, microRNA silencing, nonsense-mediated mRNA decay, and splicing. Though membrane-less, PB structures are maintained by RNA-protein and protein-protein interactions. PB proteins have intrinsically disordered regions and low complexity domains, which account for its liquid to liquid phase separation. In addition to being dynamic and actively involved in the exchange of materials with other mRNPs and organelles, they undergo changes on various cellular cues and environmental stresses, including viral infections. Interestingly, several PB proteins are individually implicated in cancer development, and no study has addressed the effects on PB dynamics after epigenetic modifications of cancer-associated PB genes. In the current review, we summarize modulations undergone by P bodies or P body components upon viral infections. Furthermore, we discuss the selective and widely investigated PB proteins that undergo methylation changes in cancer and their potential as biomarkers.
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Affiliation(s)
- Sunmathy Kanakamani
- Department of Biochemistry and Molecular Biology, Central University of Kerala, Kasargod, India
| | - Padmanaban S Suresh
- Department of Biotechnology, National Institute of Technology Calicut, Calicut, India
| | - Thejaswini Venkatesh
- Department of Biochemistry and Molecular Biology, Central University of Kerala, Kasargod, India
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10
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Pippadpally S, Venkatesh T. Deciphering piRNA biogenesis through cytoplasmic granules, mitochondria and exosomes. Arch Biochem Biophys 2020; 695:108597. [PMID: 32976825 DOI: 10.1016/j.abb.2020.108597] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/02/2020] [Revised: 09/16/2020] [Accepted: 09/19/2020] [Indexed: 12/31/2022]
Abstract
RNA systems biology is marked by a myriad of cellular processes mediated by small and long non-coding RNAs. Small non-coding RNAs include siRNAs (small interfering RNAs), miRNAs (microRNAs), tRFs(tRNA derived fragments), and piRNAs (PIWI-interacting RNAs). piRNAs are vital for the maintenance of the germ-line integrity and repress the transposons either transcriptionally or post-transcriptionally. Studies based on model organisms have shown that defects in the piRNA pathway exhibit impaired gametogenesis and loss of fertility. piRNA biogenesis is marked by transcription of precursor molecules and their subsequent processing in the cytoplasm to generate mature piRNAs. Their biogenesis is unique and complex, which involves non-canonical transcription and self-amplification mechanisms such as the ping-pong cycle. piRNA biogenesis is different in somatic and germ cells and involves the role of cytoplasmic granules in addition to mitochondria. In this review, we discuss the biogenesis and maturation of piRNAs in various cytoplasmic granules such as Yb and nuage bodies. Also, we review the role of P bodies, stress granules, and P granules, and membrane-bound compartments such as mitochondria and exosomes in piRNA biogenesis.
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Affiliation(s)
- Srikanth Pippadpally
- Department of Biochemistry and Molecular Biology, Central University of Kerala, Kasargod, 671316, India
| | - Thejaswini Venkatesh
- Department of Biochemistry and Molecular Biology, Central University of Kerala, Kasargod, 671316, India.
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11
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Roithová A, Feketová Z, Vaňáčová Š, Staněk D. DIS3L2 and LSm proteins are involved in the surveillance of Sm ring-deficient snRNAs. Nucleic Acids Res 2020; 48:6184-6197. [PMID: 32374871 PMCID: PMC7293007 DOI: 10.1093/nar/gkaa301] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/19/2019] [Revised: 04/06/2020] [Accepted: 04/23/2020] [Indexed: 01/31/2023] Open
Abstract
Spliceosomal small nuclear ribonucleoprotein particles (snRNPs) undergo a complex maturation pathway containing multiple steps in the nucleus and in the cytoplasm. snRNP biogenesis is strictly proofread and several quality control checkpoints are placed along the pathway. Here, we analyzed the fate of small nuclear RNAs (snRNAs) that are unable to acquire a ring of Sm proteins. We showed that snRNAs lacking the Sm ring are unstable and accumulate in P-bodies in an LSm1-dependent manner. We further provide evidence that defective snRNAs without the Sm binding site are uridylated at the 3′ end and associate with DIS3L2 3′→5′ exoribonuclease and LSm proteins. Finally, inhibition of 5′→3′ exoribonuclease XRN1 increases association of ΔSm snRNAs with DIS3L2, which indicates competition and compensation between these two degradation enzymes. Together, we provide evidence that defective snRNAs without the Sm ring are uridylated and degraded by alternative pathways involving either DIS3L2 or LSm proteins and XRN1.
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Affiliation(s)
- Adriana Roithová
- Laboratory of RNA Biology, Institute of Molecular Genetics of the Czech Academy of Sciences, Videnska 1083, 14220 Prague, Czech Republic.,Faculty of Science, Charles University, 128 00 Prague, Czech Republic
| | - Zuzana Feketová
- CEITEC-Central European Institute of Technology, Masaryk University, Kamenice 5/A35, 625 00 Brno, Czech Republic
| | - Štěpánka Vaňáčová
- CEITEC-Central European Institute of Technology, Masaryk University, Kamenice 5/A35, 625 00 Brno, Czech Republic
| | - David Staněk
- Laboratory of RNA Biology, Institute of Molecular Genetics of the Czech Academy of Sciences, Videnska 1083, 14220 Prague, Czech Republic
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12
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InsP 7 is a small-molecule regulator of NUDT3-mediated mRNA decapping and processing-body dynamics. Proc Natl Acad Sci U S A 2020; 117:19245-19253. [PMID: 32727897 DOI: 10.1073/pnas.1922284117] [Citation(s) in RCA: 22] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022] Open
Abstract
Regulation of enzymatic 5' decapping of messenger RNA (mRNA), which normally commits transcripts to their destruction, has the capacity to dynamically reshape the transcriptome. For example, protection from 5' decapping promotes accumulation of mRNAs into processing (P) bodies-membraneless, biomolecular condensates. Such compartmentalization of mRNAs temporarily removes them from the translatable pool; these repressed transcripts are stabilized and stored until P-body dissolution permits transcript reentry into the cytosol. Here, we describe regulation of mRNA stability and P-body dynamics by the inositol pyrophosphate signaling molecule 5-InsP7 (5-diphosphoinositol pentakisphosphate). First, we demonstrate 5-InsP7 inhibits decapping by recombinant NUDT3 (Nudix [nucleoside diphosphate linked moiety X]-type hydrolase 3) in vitro. Next, in intact HEK293 and HCT116 cells, we monitored the stability of a cadre of NUDT3 mRNA substrates following CRISPR-Cas9 knockout of PPIP5Ks (diphosphoinositol pentakisphosphate 5-kinases type 1 and 2, i.e., PPIP5K KO), which elevates cellular 5-InsP7 levels by two- to threefold (i.e., within the physiological rheostatic range). The PPIP5K KO cells exhibited elevated levels of NUDT3 mRNA substrates and increased P-body abundance. Pharmacological and genetic attenuation of 5-InsP7 synthesis in the KO background reverted both NUDT3 mRNA substrate levels and P-body counts to those of wild-type cells. Furthermore, liposomal delivery of a metabolically resistant 5-InsP7 analog into wild-type cells elevated levels of NUDT3 mRNA substrates and raised P-body abundance. In the context that cellular 5-InsP7 levels normally fluctuate in response to changes in the bioenergetic environment, regulation of mRNA structure by this inositol pyrophosphate represents an epitranscriptomic control process. The associated impact on P-body dynamics has relevance to regulation of stem cell differentiation, stress responses, and, potentially, amelioration of neurodegenerative diseases and aging.
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13
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Gao C, Wang Y. mRNA Metabolism in Cardiac Development and Disease: Life After Transcription. Physiol Rev 2020; 100:673-694. [PMID: 31751167 PMCID: PMC7327233 DOI: 10.1152/physrev.00007.2019] [Citation(s) in RCA: 21] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/08/2019] [Revised: 09/06/2019] [Accepted: 10/30/2019] [Indexed: 02/06/2023] Open
Abstract
The central dogma of molecular biology illustrates the importance of mRNAs as critical mediators between genetic information encoded at the DNA level and proteomes/metabolomes that determine the diverse functional outcome at the cellular and organ levels. Although the total number of protein-producing (coding) genes in the mammalian genome is ~20,000, it is evident that the intricate processes of cardiac development and the highly regulated physiological regulation in the normal heart, as well as the complex manifestation of pathological remodeling in a diseased heart, would require a much higher degree of complexity at the transcriptome level and beyond. Indeed, in addition to an extensive regulatory scheme implemented at the level of transcription, the complexity of transcript processing following transcription is dramatically increased. RNA processing includes post-transcriptional modification, alternative splicing, editing and transportation, ribosomal loading, and degradation. While transcriptional control of cardiac genes has been a major focus of investigation in recent decades, a great deal of progress has recently been made in our understanding of how post-transcriptional regulation of mRNA contributes to transcriptome complexity. In this review, we highlight some of the key molecular processes and major players in RNA maturation and post-transcriptional regulation. In addition, we provide an update to the recent progress made in the discovery of RNA processing regulators implicated in cardiac development and disease. While post-transcriptional modulation is a complex and challenging problem to study, recent technological advancements are paving the way for a new era of exciting discoveries and potential clinical translation in the context of cardiac biology and heart disease.
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Affiliation(s)
- Chen Gao
- Departments of Anesthesiology, Medicine, and Physiology, David Geffen School of Medicine, University of California at Los Angeles, Los Angeles, California
| | - Yibin Wang
- Departments of Anesthesiology, Medicine, and Physiology, David Geffen School of Medicine, University of California at Los Angeles, Los Angeles, California
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Li J, Hochstrasser M. Microautophagy regulates proteasome homeostasis. Curr Genet 2020; 66:683-687. [PMID: 32077993 DOI: 10.1007/s00294-020-01059-x] [Citation(s) in RCA: 20] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/15/2020] [Revised: 01/28/2020] [Accepted: 01/30/2020] [Indexed: 02/06/2023]
Abstract
Proteasomes are highly abundant protein complexes that are responsible for most regulated protein degradation in cells under favorable growth conditions. When yeast cells are under nutritional stress, most proteasomes exit the nucleus and either accumulate in cytoplasmic condensates called proteasome storage granules (PSGs) or are directed to the vacuole by autophagy. Nitrogen starvation does not cause PSG formation but leads to degradation of proteasomes through the classical macroautophagy pathway. By contrast, carbon starvation or extended incubation in stationary phase results in both PSG formation and macroautophagy of proteasomes. Unexpectedly, we found that glucose limitation also causes proteasomes to be taken up directly into vacuoles by a microautophagy mechanism. Macro- and micro-autophagy occur in parallel in glucose-starved cells, and microautophagy appears biased toward aberrant or inactive proteasomes, leaving functional proteasomes to accumulate in PSGs. PSGs dissolve and proteasomes remobilize to the nucleus within minutes after glucose refeeding. We showed that AMP-activated protein kinase (AMPK) and endosomal-sorting-complex-required-for-transport (ESCRT) factors are required for proteasome microautophagy and also impact PSG dissipation and nuclear reimport of proteasomes after glucose refeeding. The insoluble protein deposit (IPOD) compartment provides an alternative means of proteasome homeostasis, including when microautophagy is impaired. Our findings reveal a surprising diversity of mechanisms for proteasome quality and quantity control during starvation. A mechanistic understanding of the AMPK-regulated ESCRT-mediated microautophagy pathway could provide new avenues for manipulating proteasome homeostasis and treating human disease.
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Affiliation(s)
- Jianhui Li
- Department of Molecular Biophysics and Biochemistry, Yale University, New Haven, CT, 06520, USA
| | - Mark Hochstrasser
- Department of Molecular Biophysics and Biochemistry, Yale University, New Haven, CT, 06520, USA. .,Department of Molecular, Cellular, and Developmental Biology, Yale University, New Haven, CT, 06520, USA.
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DEKTV and YVG motifs in the Lsm domain are important for the activity of Scd6, a conserved translation repressor protein. BIOCHIMICA ET BIOPHYSICA ACTA-GENE REGULATORY MECHANISMS 2020; 1863:194474. [PMID: 31926930 DOI: 10.1016/j.bbagrm.2019.194474] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/24/2019] [Revised: 12/17/2019] [Accepted: 12/17/2019] [Indexed: 12/29/2022]
Abstract
Scd6 is a conserved RGG-motif protein which represses translation by binding eIF4G through its RGG-motif. Lsm and FDF are two other conserved domains present in the protein, however the role of both these domains is unclear. We provide evidence in this report that the Lsm domain is important for the role of Scd6 in translation. Mutant of Scd6 lacking the Lsm domain does not cause overexpression growth defect in a manner comparable to the wild type. Similar results were observed with two distinct point mutants of Scd6 wherein putative RNA-binding motifs DxEKxTV and YVG were mutated. Upon overexpression, the three mutants were defective in inducing formation of P-bodies and stress granules which are conserved sites of translation repression. Importantly localization to granules in response to glucose deprivation and sodium azide stress was defective for Lsm domain mutants indicating that the inability to localize to granules could be a reason for their defective role in translation. Deletion of scd6 impairs Lsm1 foci formation upon glucose deprivation stress which could not be rescued by complementation with Lsm-domain deletion mutant of Scd6 when compared to the full-length protein. Put together, our results highlight the role of Lsm domain and its specific motifs in Scd6 activity and provide crucial insight into its function.
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