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Han H, Wang Y, Zheng T, Peng Q, Qiu L, Hu X, Lin H, Xi D. NtAGO1 positively regulates the generation and viral resistance of dark green islands in Nicotiana tabacum. Plant Physiol Biochem 2022; 174:1-10. [PMID: 35121480 DOI: 10.1016/j.plaphy.2022.01.028] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/27/2021] [Revised: 01/20/2022] [Accepted: 01/24/2022] [Indexed: 06/14/2023]
Abstract
Dark green islands (DGIs) are the outcome of post-transcriptional gene silencing (PTGS) in antiviral immunity, but their characteristics related to PTGS remain largely unknown. In this study, the cucumber mosaic virus (CMV) was inoculated on Nicotiana tabacum plants to explore the PTGS features of DGIs. Our results showed that higher expressions of PTGS-associated genes, especially NtAGO1, present in DGIs. To investigate the role of NtAGO1 in the generation and the antiviral effect of DGIs, NtAGO1 was then over-expressed or knocked out in N. tabacum plants through agrobacterium-mediated genetic transformation. The results showed that more DGIs with larger areas appeared on NtAGO1 over-expressed plants, accompanied by less virus accumulation, less reactive oxygen species production, and seldom membrane damage, whereas fewer DGIs appeared on NtAGO1 knockout plants with more damage on infected plants. In addition, the NtAGO1-participated antiviral process could promote the transduction of the salicylic acid-mediated defense pathway. Taken together, our results indicate that DGIs are maintained by a stronger PTGS mechanism, and NtAGO1 positively regulates the generation and viral resistance of DGIs in N. tabacum.
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Affiliation(s)
- Hongyan Han
- Key Laboratory of Bio-Resource and Eco-Environment of Ministry of Education, College of Life Sciences, Sichuan University, Chengdu, 610065, Sichuan, China
| | - Yunru Wang
- Key Laboratory of Bio-Resource and Eco-Environment of Ministry of Education, College of Life Sciences, Sichuan University, Chengdu, 610065, Sichuan, China
| | - Tianrui Zheng
- Key Laboratory of Bio-Resource and Eco-Environment of Ministry of Education, College of Life Sciences, Sichuan University, Chengdu, 610065, Sichuan, China
| | - Qiding Peng
- Key Laboratory of Bio-Resource and Eco-Environment of Ministry of Education, College of Life Sciences, Sichuan University, Chengdu, 610065, Sichuan, China
| | - Long Qiu
- Key Laboratory of Bio-Resource and Eco-Environment of Ministry of Education, College of Life Sciences, Sichuan University, Chengdu, 610065, Sichuan, China
| | - Xinyue Hu
- Key Laboratory of Bio-Resource and Eco-Environment of Ministry of Education, College of Life Sciences, Sichuan University, Chengdu, 610065, Sichuan, China
| | - Honghui Lin
- Key Laboratory of Bio-Resource and Eco-Environment of Ministry of Education, College of Life Sciences, Sichuan University, Chengdu, 610065, Sichuan, China
| | - Dehui Xi
- Key Laboratory of Bio-Resource and Eco-Environment of Ministry of Education, College of Life Sciences, Sichuan University, Chengdu, 610065, Sichuan, China.
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Ghosh S, Guimaraes JC, Lanzafame M, Schmidt A, Syed AP, Dimitriades B, Börsch A, Ghosh S, Mittal N, Montavon T, Correia AL, Danner J, Meister G, Terracciano LM, Pfeffer S, Piscuoglio S, Zavolan M. Prevention of dsRNA-induced interferon signaling by AGO1x is linked to breast cancer cell proliferation. EMBO J 2020; 39:e103922. [PMID: 32812257 PMCID: PMC7507497 DOI: 10.15252/embj.2019103922] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/06/2019] [Revised: 06/27/2020] [Accepted: 07/07/2020] [Indexed: 01/05/2023] Open
Abstract
Translational readthrough, i.e., elongation of polypeptide chains beyond the stop codon, was initially reported for viral RNA, but later found also on eukaryotic transcripts, resulting in proteome diversification and protein‐level modulation. Here, we report that AGO1x, an evolutionarily conserved translational readthrough isoform of Argonaute 1, is generated in highly proliferative breast cancer cells, where it curbs accumulation of double‐stranded RNAs (dsRNAs) and consequent induction of interferon responses and apoptosis. In contrast to other mammalian Argonaute protein family members with primarily cytoplasmic functions, AGO1x exhibits nuclear localization in the vicinity of nucleoli. We identify AGO1x interaction with the polyribonucleotide nucleotidyltransferase 1 (PNPT1) and show that the depletion of this protein further augments dsRNA accumulation. Our study thus uncovers a novel function of an Argonaute protein in buffering the endogenous dsRNA‐induced interferon responses, different than the canonical function of AGO proteins in the miRNA effector pathway. As AGO1x expression is tightly linked to breast cancer cell proliferation, our study thus suggests a new direction for limiting tumor growth.
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Affiliation(s)
- Souvik Ghosh
- Computational and Systems Biology, Biozentrum, University of Basel, Basel, Switzerland
| | - Joao C Guimaraes
- Computational and Systems Biology, Biozentrum, University of Basel, Basel, Switzerland
| | - Manuela Lanzafame
- Institute of Pathology, University Hospital Basel, Basel, Switzerland
| | - Alexander Schmidt
- Proteomics Core Facility, Biozentrum, University of Basel, Basel, Switzerland
| | - Afzal Pasha Syed
- Computational and Systems Biology, Biozentrum, University of Basel, Basel, Switzerland
| | - Beatrice Dimitriades
- Computational and Systems Biology, Biozentrum, University of Basel, Basel, Switzerland
| | - Anastasiya Börsch
- Computational and Systems Biology, Biozentrum, University of Basel, Basel, Switzerland
| | - Shreemoyee Ghosh
- Computational and Systems Biology, Biozentrum, University of Basel, Basel, Switzerland
| | - Nitish Mittal
- Computational and Systems Biology, Biozentrum, University of Basel, Basel, Switzerland
| | - Thomas Montavon
- Architecture et Réactivité de l'ARN, Institut de biologie moléculaire et cellulaire du CNRS, Université de Strasbourg, Strasbourg, France
| | - Ana Luisa Correia
- Department of Biomedicine, University of Basel/University Hospital Basel, Basel, Switzerland
| | - Johannes Danner
- Department of Biochemistry, Department of Biology and Preclinical Medicine, University of Regensburg, Regensburg, Germany
| | - Gunter Meister
- Department of Biochemistry, Department of Biology and Preclinical Medicine, University of Regensburg, Regensburg, Germany
| | | | - Sébastien Pfeffer
- Architecture et Réactivité de l'ARN, Institut de biologie moléculaire et cellulaire du CNRS, Université de Strasbourg, Strasbourg, France
| | - Salvatore Piscuoglio
- Institute of Pathology, University Hospital Basel, Basel, Switzerland.,Department of Biomedicine, University of Basel/University Hospital Basel, Basel, Switzerland
| | - Mihaela Zavolan
- Computational and Systems Biology, Biozentrum, University of Basel, Basel, Switzerland
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Malik S, Jang W, Kim JY, Kim C. Mechanisms ensuring robust repression of the Drosophila female germline stem cell maintenance factor Nanos via posttranscriptional regulation. FASEB J 2020; 34:11421-11430. [PMID: 32654316 DOI: 10.1096/fj.202000656r] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/23/2020] [Revised: 04/28/2020] [Accepted: 04/29/2020] [Indexed: 12/22/2022]
Abstract
During oogenesis in the Drosophila ovary, numerous translational regulators promote the self-renewal or differentiation of stem cells. An intriguing question is how these regulators combine to execute translational regulation. Here, we study mechanisms for the posttranscriptional regulation of nos, a critical stem cell self-renewal factor in the Drosophila ovary; specifically, regulators that promote differentiation of the stem cell daughter. Previous studies showed that Bam, Bgcn, Mei-P26, and Sxl form a complex and repress nos expression through the nos 3'UTR. To further elucidate mechanistic processes of Nos translational regulation, we reconstituted nos repression in cultured Drosophila cells. We identify Ago1 and Brat as new members, and show that Ago1 acts through miRNA binding sites in the proximal region of the nos 3'UTR, whereas Sxl acts via an Sxl binding sequence in the distal region. Combining these findings with published reports, we propose that additional factors Bam, Bgcn, Mei-P26, and Brat are recruited to nos mRNAs through interaction with Ago1 and Sxl. These findings elucidate mechanisms of nos regulation by diverse translational repressors.
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Affiliation(s)
- Sumira Malik
- Amity Institute of Biotechnology, Amity University Jharkhand, Ranchi, India
| | - Wijeong Jang
- School of Biological Sciences and Technology, Chonnam National University, Gwangju, South Korea
| | - Ji Young Kim
- School of Biological Sciences and Technology, Chonnam National University, Gwangju, South Korea
| | - Changsoo Kim
- School of Biological Sciences and Technology, Chonnam National University, Gwangju, South Korea
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Zhang X, Aksoy E, Girke T, Raikhel AS, Karginov FV. Transcriptome-wide microRNA and target dynamics in the fat body during the gonadotrophic cycle of Aedes aegypti. Proc Natl Acad Sci U S A 2017; 114:E1895-903. [PMID: 28223504 DOI: 10.1073/pnas.1701474114] [Citation(s) in RCA: 34] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022] Open
Abstract
The mosquito Aedes aegypti is a major vector of numerous viral diseases, because it requires a blood meal to facilitate egg development. The fat body, a counterpart of mammalian liver and adipose tissues, is the metabolic center, playing a key role in reproduction. Therefore, understanding of regulatory networks controlling its functions is critical, and the role of microRNAs (miRNAs) in the process is largely unknown. We aimed to explore miRNA expression and potential targets in the female fat body of Ae. aegypti, as well as their changes postblood meal (PBM). Small RNA library analysis revealed five unique miRNA patterns sequentially expressed at five sampled time points, likely responding to, and affecting, waves of upstream hormonal signals and gene expression in the same period. To link miRNA identities with downstream targets, transcriptome-wide mRNA 3' UTR interaction sites were experimentally determined at 72 h posteclosion and 24 h PBM through Argonaute 1 cross-linking and immunoprecipitation followed by high-throughput sequencing. Several target sites were validated by means of in vitro luciferase assays with wild-type and mutated 3' UTRs for six miRNA families. With established transgenic lines, consistent results were observed with spatiotemporal knockdown of miR-8 and luciferase assays. We further investigated miRNAs potentially regulating various physiological processes based on Clusters of Orthologous Groups functional categories. Hence, the present work comprehensively elucidated miRNA expression and target dynamics in the female mosquito fat body, providing a solid foundation for future functional studies of miRNA regulation during the gonadotrophic cycle.
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Iio A, Takagi T, Miki K, Naoe T, Nakayama A, Akao Y. DDX6 post-transcriptionally down-regulates miR-143/145 expression through host gene NCR143/145 in cancer cells. Biochim Biophys Acta. 2013;1829:1102-1110. [PMID: 23932921 DOI: 10.1016/j.bbagrm.2013.07.010] [Citation(s) in RCA: 45] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/17/2012] [Revised: 07/26/2013] [Accepted: 07/31/2013] [Indexed: 12/15/2022]
Abstract
In various human malignancies, widespread dysregulation of microRNA (miRNA) expression is reported to occur and affects various cell growth programs. Recent studies suggest that the expression levels of miRNAs that act as tumor suppressors are frequently reduced in cancers because of chromosome deletions, epigenetical changes, aberrant transcription, and disturbances in miRNA processing. MiR-143 and -145 are well-recognized miRNAs that are highly expressed in several tissues, but down-regulated in most types of cancers. However, the mechanism of this down-regulation has not been investigated in detail. Here, we show that DEAD-box RNA helicase 6, DDX6 (p54/RCK), post-transcriptionally down-regulated miR-143/145 expression by prompting the degradation of its host gene product, NCR143/145 RNA. In human gastric cancer cell line MKN45, DDX6 protein was abundantly expressed and accumulated in processing bodies (P-bodies). DDX6 preferentially increased the instability of non-coding RNA, NCR143/145, which encompasses the miR-143/145 cluster, and down-regulated the expression of mature miR-143/145. In human monocytic cell line THP-1, lipopolysaccharide treatment promoted the assembly of P-bodies and down-regulated the expression of NCR143/145 and its miR-143/145 rapidly. In these cells, cycloheximide treatment led to a loss of P-bodies and to an increase in NCR143/145 RNA stability, thus resulting in up-regulation of miR-143/145 expression. These data demonstrate that DDX6 contributed to the control of NCR143/145 RNA stability in P-bodies and post-transcriptionally regulated miR-143/145 expression in cancer cells.
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