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Lee S, Kuramochi-Miyagawa S, Nagamori I, Nakano T. Effects of transgene insertion loci and copy number on Dnmt3L gene silencing through antisense transgene-derived PIWI-interacting RNAs. RNA (NEW YORK, N.Y.) 2022; 28:683-696. [PMID: 35145000 PMCID: PMC9014882 DOI: 10.1261/rna.078905.121] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 07/13/2021] [Accepted: 01/24/2022] [Indexed: 06/14/2023]
Abstract
PIWI-interacting RNAs (piRNAs), which are germ cell-specific small RNAs, are essential for spermatogenesis. In fetal mouse germ cells, piRNAs are synthesized from sense and antisense RNAs of transposable element sequences for retrotransposon silencing. In a previous study, we reported that transgenic mice expressing antisense-Dnmt3L under the control of the Miwi2 promoter (Tg-Miwi2P-asDnmt3L) exhibited piRNA-mediated DNMT3L down-regulation. In this study, two transgene integration loci (B3 and E1) were identified on chromosome 18 of the Tg-Miwi2P-asDnmt3L mice; these loci were weak piRNA clusters. Crossbreeding was performed to obtain mice with the transgene cassette inserted into a single locus. DNMT3L was silenced and spermatogenesis was severely impaired in mice with the transgene cassette inserted at the B3 locus (Tg-B mice). In contrast, spermatogenesis in mice bearing the transgene at the E1 locus (Tg-E mice) was normal. The number of piRNAs for Dnmt3L in Tg-B mice was eightfold higher than that in Tg-E mice. Therefore, both gene silencing and impaired spermatogenesis depended on the transgene copy number rather than on the insertion loci. Additionally, the endogenous Dnmt3L promoter was not methylated in Tg mice, suggesting that Dnmt3L silencing was caused by post-transcriptional gene silencing. Based on these data, we discuss a piRNA-dependent gene silencing mechanism against novel gene insertions.
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Affiliation(s)
- SePil Lee
- Graduate School of Frontier Biosciences, Osaka University, Yamada-oka 2-2 Suita, Osaka 565-0871, Japan
| | - Satomi Kuramochi-Miyagawa
- Graduate School of Frontier Biosciences, Osaka University, Yamada-oka 2-2 Suita, Osaka 565-0871, Japan
- Medical School, Department of Pathology, Osaka University, Yamada-oka 2-2 Suita, Osaka 565-0871, Japan
| | - Ippei Nagamori
- Medical School, Department of Pathology, Osaka University, Yamada-oka 2-2 Suita, Osaka 565-0871, Japan
| | - Toru Nakano
- Graduate School of Frontier Biosciences, Osaka University, Yamada-oka 2-2 Suita, Osaka 565-0871, Japan
- Medical School, Department of Pathology, Osaka University, Yamada-oka 2-2 Suita, Osaka 565-0871, Japan
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Katsuma S, Shoji K, Suzuki Y, Iwanaga M. Potential for small RNA production against Bombyx mori latent virus in Bombyx mori ovaries. ARCHIVES OF INSECT BIOCHEMISTRY AND PHYSIOLOGY 2021; 106:e21761. [PMID: 33225529 DOI: 10.1002/arch.21761] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/10/2020] [Revised: 10/22/2020] [Accepted: 11/03/2020] [Indexed: 06/11/2023]
Abstract
Bombyx mori latent virus (BmLV) is a positive, single-stranded insect RNA virus closely related to plant maculaviruses. BmLV was first isolated from Bombyx mori ovary-derived cell line BmN-4, and this virus has already infected most B. mori-derived cultured cell lines. We previously reported that small interfering RNA (siRNA) and PIWI-interacting RNA (piRNA) pathways function cooperatively to maintain the amount of BmLV RNA for normal BmN-4 cell growth. On the other hand, BmLV does not propagate in B. mori larvae. Here we conducted BmLV injection into the larval body cavities of B. mori, and examined BmLV accumulation in larval ovaries where siRNA and piRNA pathways are both active, to investigate whether this in vivo resistance is governed by small RNA pathways. Expression levels of RNA-dependent RNA polymerase, coat protein, and p15 genes in BmLV-injected larval ovaries were extremely low compared with those in B. mori cultured cells, indicating that B. mori larval ovaries are more resistant to BmLV than B. mori cultured cells. We also sequenced small RNAs prepared from BmLV-injected larval ovaries and mapped them onto the BmLV genome. Although their amounts were very small, we were able to detect BmLV-derived small RNAs in the ovaries. According to their length distribution and nucleotide bias, they were likely to be siRNAs and piRNAs. These results suggest that B. mori ovaries can potentially produce small RNAs against BmLV, but the resistance of larval ovaries against BmLV is not dependent on RNA silencing pathways.
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Affiliation(s)
- Susumu Katsuma
- Department of Agricultural and Environmental Biology, Graduate School of Agricultural and Life Sciences, The University of Tokyo, Bunkyo-ku, Tokyo, Japan
| | - Keisuke Shoji
- Institute of Molecular and Cellular Biosciences, The University of Tokyo, Bunkyo-ku, Tokyo, Japan
| | - Yutaka Suzuki
- Department of Computational Biology and Medical Sciences, The University of Tokyo, Kashiwa, Chiba, Japan
| | - Masashi Iwanaga
- Department of Agrobiology and Bioresources, Utsunomiya University, Utsunomiya-shi, Tochigi, Japan
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Katsuma S, Kawamoto M, Shoji K, Aizawa T, Kiuchi T, Izumi N, Ogawa M, Mashiko T, Kawasaki H, Sugano S, Tomari Y, Suzuki Y, Iwanaga M. Transcriptome profiling reveals infection strategy of an insect maculavirus. DNA Res 2018; 25:4816134. [PMID: 29360973 PMCID: PMC6014269 DOI: 10.1093/dnares/dsx056] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/21/2017] [Accepted: 01/03/2018] [Indexed: 11/14/2022] Open
Abstract
Bombyx mori macula-like virus (BmMLV) is a positive, single-stranded insect RNA virus that is closely related to plant maculaviruses. BmMLV is currently characterized as an unclassified maculavirus. BmMLV accumulates at extremely high levels in cell lines derived from the silkworm, Bombyx mori, but it does not lead to lethality and establishes persistent infections. It is unknown how this insect maculavirus replicates and establishes persistent infections in insect cells. Here, we showed that BmMLV p15, which is located on a subgenomic fragment and is not found in plant maculaviruses, is highly expressed in BmMLV-infected silkworm cells and that p15 protein is required to establish BmMLV infections in silkworm cells. We also showed that two distinct small RNA-mediated pathways maintain BmMLV levels in BmMLV-infected silkworm cells, thereby allowing the virus to establish persistent infection. Virus-derived siRNAs and piRNAs were both produced as the infection progressed. Knockdown experiments demonstrated that the exogenous RNAi pathway alone or RNAi and piRNA pathways function cooperatively to silence BmMLV RNA and that both pathways are important for normal growth of BmMLV-infected silkworm cells. On the basis of our study, we propose a mechanism of how a plant virus-like insect virus can establish persistent infections in insect cells.
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Affiliation(s)
- Susumu Katsuma
- Department of Agricultural and Environmental Biology, Graduate School of Agricultural and Life Sciences, The University of Tokyo, Bunkyo-ku, Tokyo 113-8657, Japan
| | - Munetaka Kawamoto
- Department of Agricultural and Environmental Biology, Graduate School of Agricultural and Life Sciences, The University of Tokyo, Bunkyo-ku, Tokyo 113-8657, Japan
| | - Keisuke Shoji
- Department of Agricultural and Environmental Biology, Graduate School of Agricultural and Life Sciences, The University of Tokyo, Bunkyo-ku, Tokyo 113-8657, Japan
- Department of Agrobiology and Bioresources, School of Agriculture, Utsunomiya University, Utsunomiya-shi, Tochigi 321-8505, Japan
| | - Takahiro Aizawa
- Department of Agrobiology and Bioresources, School of Agriculture, Utsunomiya University, Utsunomiya-shi, Tochigi 321-8505, Japan
| | - Takashi Kiuchi
- Department of Agricultural and Environmental Biology, Graduate School of Agricultural and Life Sciences, The University of Tokyo, Bunkyo-ku, Tokyo 113-8657, Japan
| | - Natsuko Izumi
- Institute of Molecular and Cellular Biosciences, The University of Tokyo, Bunkyo-ku, Tokyo 113-0032, Japan
| | - Moe Ogawa
- Department of Agrobiology and Bioresources, School of Agriculture, Utsunomiya University, Utsunomiya-shi, Tochigi 321-8505, Japan
| | - Takaaki Mashiko
- Department of Biological Production Science, United Graduate School of Agricultural Science, Tokyo University of Agriculture and Technology, Fuchu-shi, Tokyo 183-8509, Japan
| | - Hideki Kawasaki
- Department of Agrobiology and Bioresources, School of Agriculture, Utsunomiya University, Utsunomiya-shi, Tochigi 321-8505, Japan
| | - Sumio Sugano
- Department of Computational Biology and Medical Sciences, Graduate School of Frontier Sciences, The University of Tokyo, Minato-ku, Tokyo 108-8639, Japan
| | - Yukihide Tomari
- Institute of Molecular and Cellular Biosciences, The University of Tokyo, Bunkyo-ku, Tokyo 113-0032, Japan
- Department of Computational Biology and Medical Sciences, Graduate School of Frontier Sciences, The University of Tokyo, Bunkyo-ku, Tokyo 113-0032, Japan
| | - Yutaka Suzuki
- Department of Computational Biology and Medical Sciences, Graduate School of Frontier Sciences, The University of Tokyo, Kashiwa, Chiba 277-0882, Japan
| | - Masashi Iwanaga
- Department of Agrobiology and Bioresources, School of Agriculture, Utsunomiya University, Utsunomiya-shi, Tochigi 321-8505, Japan
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Shoji K, Suzuki Y, Sugano S, Shimada T, Katsuma S. Artificial "ping-pong" cascade of PIWI-interacting RNA in silkworm cells. RNA (NEW YORK, N.Y.) 2017; 23:86-97. [PMID: 27777367 PMCID: PMC5159652 DOI: 10.1261/rna.058875.116] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/24/2016] [Accepted: 10/15/2016] [Indexed: 05/19/2023]
Abstract
PIWI-interacting RNAs (piRNAs) play essential roles in the defense system against selfish elements in animal germline cells by cooperating with PIWI proteins. A subset of piRNAs is predicted to be generated via the "ping-pong" cascade, which is mainly controlled by two different PIWI proteins. Here we established a cell-based artificial piRNA production system using a silkworm ovarian cultured cell line that is believed to possess a complete piRNA pathway. In addition, we took advantage of a unique silkworm sex-determining one-to-one ping-pong piRNA pair, which enabled us to precisely monitor the behavior of individual artificial piRNAs. With this novel strategy, we successfully generated artificial piRNAs against endogenous protein-coding genes via the expected back-and-forth traveling mechanism. Furthermore, we detected "primary" piRNAs from the upstream region of the artificial "ping-pong" site in the endogenous gene. This artificial piRNA production system experimentally confirms the existence of the "ping-pong" cascade of piRNAs. Also, this system will enable us to identify the factors involved in both, or each, of the "ping" and "pong" cascades and the sequence features that are required for efficient piRNA production.
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Affiliation(s)
- Keisuke Shoji
- Department of Agricultural and Environmental Biology, Graduate School of Agricultural and Life Sciences, The University of Tokyo, Bunkyo-ku, Tokyo 113-8657, Japan
| | - Yutaka Suzuki
- Department of Computational Biology and Medical Sciences, Graduate School of Frontier Sciences, The University of Tokyo, Kashiwa, Chiba 277-0882, Japan
| | - Sumio Sugano
- Department of Computational Biology and Medical Sciences, Graduate School of Frontier Sciences, The University of Tokyo, Minato-ku, Tokyo 108-8639, Japan
| | - Toru Shimada
- Department of Agricultural and Environmental Biology, Graduate School of Agricultural and Life Sciences, The University of Tokyo, Bunkyo-ku, Tokyo 113-8657, Japan
| | - Susumu Katsuma
- Department of Agricultural and Environmental Biology, Graduate School of Agricultural and Life Sciences, The University of Tokyo, Bunkyo-ku, Tokyo 113-8657, Japan
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Abstract
Our paper reports a novel strategy for the artificial introduction of DNA methylation in mouse gonocytes. The manuscript presents data showing that the concomitant expression of sense and anti-sense of EGFP transgenes in embryonic male germ cells induces gene silencing via the piRNA pathway and that the expression of an antisense Dnmt3L transgene induces silencing of the endogenous Dnmt3L gene.
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Affiliation(s)
- Satomi Kuramochi-Miyagawa
- Department of Pathology, Medical School, Osaka University, Yamada-oka 2-2 Suita, Osaka 565-0871, Japan
| | - Toru Nakano
- Department of Pathology, Medical School, Osaka University, Yamada-oka 2-2 Suita, Osaka 565-0871, Japan; Department of Graduate School of Frontier Biosciences, Osaka University, Yamada-oka 2-2 Suita, Osaka 565-0871, Japan.
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