1
|
Chen Y, Bai B, Yan H, Wen F, Qin D, Jander G, Xia Q, Wang G. Systemic disruption of the homeostasis of transfer RNA isopentenyltransferase causes growth and development abnormalities in Bombyx mori. INSECT MOLECULAR BIOLOGY 2019; 28:380-391. [PMID: 30548717 DOI: 10.1111/imb.12561] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/09/2023]
Abstract
Isopentenylation at A37 (i6 A37) of some transfer RNAs (tRNAs) plays a vital role in regulating the efficiency and fidelity of protein synthesis. However, whether insects, which are well known for their highly efficient protein synthesis machinery, employ this regulatory mechanism remains uninvestigated. In the current study, a candidate tRNA isopentenyltransferase (IPT) gene with three alternative splicing isoforms (BmIPT1-BmIPT3) was identified in Bombyx mori (silkworm). Only BmIPT1 could complement a yeast mutant lacking tRNA IPT. Phylogenetic analysis showed that silkworm tRNA IPT is conserved in the Lepidoptera. BmIPT was expressed in all B. mori tissues and organs that were investigated, but was expressed at a significantly higher level in silk glands of the fourth instar compared to the first day of the fifth instar. Interestingly, BmIPT was expressed at a significantly higher level in the domesticated silkworm, B. mori, than in wild Bombyx mandarina in multiple tissues and organs. Knock-down of BmIPT by RNA interference caused severe abnormalities in silk spinning and metamorphosis. Constitutive overexpression of BmIPT1 using a cytoplasmic actin 4 promoter in B. mori raised its messenger RNA level more than sixfold compared with nontransgenic insects and led to significant decreases in the body weight and cocoon shell ratio. Together, these results confirm the first functional tRNA IPT in insects and show that a suitable expression level of tRNA IPT is vital for silk spinning, normal growth, and metamorphosis. Thus, i6 A modification at position A37 in tRNA probably plays an important role in B. mori protein synthesis.
Collapse
Affiliation(s)
- Y Chen
- State Key Laboratory of Silkworm Genome Biology, Southwest University, Chongqing, China
| | - B Bai
- State Key Laboratory of Silkworm Genome Biology, Southwest University, Chongqing, China
| | - H Yan
- State Key Laboratory of Silkworm Genome Biology, Southwest University, Chongqing, China
| | - F Wen
- State Key Laboratory of Silkworm Genome Biology, Southwest University, Chongqing, China
| | - D Qin
- State Key Laboratory of Silkworm Genome Biology, Southwest University, Chongqing, China
| | - G Jander
- Boyce Thompson Institute, Ithaca, NY, USA
| | - Q Xia
- State Key Laboratory of Silkworm Genome Biology, Southwest University, Chongqing, China
- Chongqing Key Laboratory of Sericultural Science, Chongqing Engineering and Technology Research Center for Novel Silk Materials, Southwest University, Chongqing, China
| | - G Wang
- State Key Laboratory of Silkworm Genome Biology, Southwest University, Chongqing, China
- Chongqing Key Laboratory of Sericultural Science, Chongqing Engineering and Technology Research Center for Novel Silk Materials, Southwest University, Chongqing, China
| |
Collapse
|
2
|
Takiya S, Tsubota T, Kimoto M. Regulation of Silk Genes by Hox and Homeodomain Proteins in the Terminal Differentiated Silk Gland of the Silkworm Bombyx mori. J Dev Biol 2016; 4:E19. [PMID: 29615585 PMCID: PMC5831788 DOI: 10.3390/jdb4020019] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/29/2016] [Revised: 05/08/2016] [Accepted: 05/17/2016] [Indexed: 12/15/2022] Open
Abstract
The silk gland of the silkworm Bombyx mori is a long tubular organ that is divided into several subparts along its anteroposterior (AP) axis. As a trait of terminal differentiation of the silk gland, several silk protein genes are expressed with unique regional specificities. Most of the Hox and some of the homeobox genes are also expressed in the differentiated silk gland with regional specificities. The expression patterns of Hox genes in the silk gland roughly correspond to those in embryogenesis showing "colinearity". The central Hox class protein Antennapedia (Antp) directly regulates the expression of several middle silk gland-specific silk genes, whereas the Lin-1/Isl-1/Mec3 (LIM)-homeodomain transcriptional factor Arrowhead (Awh) regulates the expression of posterior silk gland-specific genes for silk fiber proteins. We summarize our results and discuss the usefulness of the silk gland of Bombyx mori for analyzing the function of Hox genes. Further analyses of the regulatory mechanisms underlying the region-specific expression of silk genes will provide novel insights into the molecular bases for target-gene selection and regulation by Hox and homeodomain proteins.
Collapse
Affiliation(s)
- Shigeharu Takiya
- Shigeharu Takiya, Division of Biological Sciences and Center for Genome Dynamics, Faculty of Science, Hokkaido University, North 10, West 8, Kita-ku, Sapporo, Hokkaido 060-0810, Japan.
- Graduate School of Life Science, Hokkaido University, North 10, West 8, Kita-ku, Sapporo 060-0810, Japan.
| | - Takuya Tsubota
- Transgenic Silkworm Research Unit, Institute of Agrobiological Sciences, National Agriculture and Food Research Organization, 1-2 Owashi, Tsukuba, Ibaraki 305-8634, Japan.
| | - Mai Kimoto
- Graduate School of Life Science, Hokkaido University, North 10, West 8, Kita-ku, Sapporo 060-0810, Japan.
| |
Collapse
|
3
|
Zhao XM, Liu C, Jiang LJ, Li QY, Zhou MT, Cheng TC, Mita K, Xia QY. A juvenile hormone transcription factor Bmdimm-fibroin H chain pathway is involved in the synthesis of silk protein in silkworm, Bombyx mori. J Biol Chem 2015; 290:972-86. [PMID: 25371208 PMCID: PMC4294524 DOI: 10.1074/jbc.m114.606921] [Citation(s) in RCA: 38] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/28/2014] [Revised: 11/03/2014] [Indexed: 01/16/2023] Open
Abstract
The genes responsible for silk biosynthesis are switched on and off at particular times in the silk glands of Bombyx mori. This switch appears to be under the control of endogenous and exogenous hormones. However, the molecular mechanisms by which silk protein synthesis is regulated by the juvenile hormone (JH) are largely unknown. Here, we report a basic helix-loop-helix transcription factor, Bmdimm, its silk gland-specific expression, and its direct involvement in the regulation of fibroin H-chain (fib-H) by binding to an E-box (CAAATG) element of the fib-H gene promoter. Far-Western blots, enzyme-linked immunosorbent assays, and co-immunoprecipitation assays revealed that Bmdimm protein interacted with another basic helix-loop-helix transcription factor, Bmsage. Immunostaining revealed that Bmdimm and Bmsage proteins are co-localized in nuclei. Bmdimm expression was induced in larval silk glands in vivo, in silk glands cultured in vitro, and in B. mori cell lines after treatment with a JH analog. The JH effect on Bmdimm was mediated by the JH-Met-Kr-h1 signaling pathway, and Bmdimm expression did not respond to JH by RNA interference with double-stranded BmKr-h1 RNA. These data suggest that the JH regulatory pathway, the transcription factor Bmdimm, and the targeted fib-H gene contribute to the synthesis of fibroin H-chain protein in B. mori.
Collapse
Affiliation(s)
- Xiao-Ming Zhao
- From the State Key Laboratory of Silkworm Genome Biology and Key Sericultural Laboratory of the Ministry of Agriculture, College of Bio-Technology, Southwest University, Chongqing 400716 and the Research Institute of Applied Biology, Shanxi University, Taiyuan, Shanxi 030006, China
| | - Chun Liu
- From the State Key Laboratory of Silkworm Genome Biology and Key Sericultural Laboratory of the Ministry of Agriculture, College of Bio-Technology, Southwest University, Chongqing 400716 and
| | - Li-Jun Jiang
- From the State Key Laboratory of Silkworm Genome Biology and Key Sericultural Laboratory of the Ministry of Agriculture, College of Bio-Technology, Southwest University, Chongqing 400716 and
| | - Qiong-Yan Li
- From the State Key Laboratory of Silkworm Genome Biology and Key Sericultural Laboratory of the Ministry of Agriculture, College of Bio-Technology, Southwest University, Chongqing 400716 and
| | - Meng-Ting Zhou
- From the State Key Laboratory of Silkworm Genome Biology and Key Sericultural Laboratory of the Ministry of Agriculture, College of Bio-Technology, Southwest University, Chongqing 400716 and
| | - Ting-Cai Cheng
- From the State Key Laboratory of Silkworm Genome Biology and Key Sericultural Laboratory of the Ministry of Agriculture, College of Bio-Technology, Southwest University, Chongqing 400716 and
| | - Kazuei Mita
- From the State Key Laboratory of Silkworm Genome Biology and
| | - Qing-You Xia
- From the State Key Laboratory of Silkworm Genome Biology and Key Sericultural Laboratory of the Ministry of Agriculture, College of Bio-Technology, Southwest University, Chongqing 400716 and
| |
Collapse
|
4
|
Takiya S, Suzuki Y. Role of the Core Promoter for the Preferential Transcription of Fibroin Gene in the Posterior Silk Gland Extract. (transcription/core promoter/fibroin gene/initiator/DNase I footprint). Dev Growth Differ 1993. [DOI: 10.1111/j.1440-169x.1993.00311.x] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
|
5
|
Kamito T, Tanaka H, Sato B, Nagasawa H, Suzuki A. Nucleotide sequence of cDNA for the eclosion hormone of the silkworm, Bombyx mori, and the expression in a brain. Biochem Biophys Res Commun 1992; 182:514-9. [PMID: 1370883 DOI: 10.1016/0006-291x(92)91762-f] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
The cDNAs encoding eclosion hormone (EH) of the silkworm, Bombyx mori, were isolated and sequenced. The results showed that the pre-EH molecule contains a 26-amino acid signal peptide and a 62-amino acid mature EH. The deduced amino acid sequence agreed with that previously determined by the peptide analysis. The presence of leucine residue at the carboxyl terminal of EH, which had not been detected directly by the peptide analysis, was proved. Primer extension and Northern hybridization analyses revealed that 0.9 kb mRNA is transcribed and it has a 66-nucleotide non-translated sequence at the 5'-end region. In situ hybridization showed that the EH gene is expressed in two pairs of nuerosecretory cells in the brain of 5th instar larva.
Collapse
Affiliation(s)
- T Kamito
- Department of Agricultural Chemistry, Faculty of Agriculture, University of Tokyo, Japan
| | | | | | | | | |
Collapse
|
6
|
|
7
|
Tamura T, Kanda T, Takiya S, Okano K, Maekawa H. Transient expression of chimeric CAT genes injected into early embryos of the domesticated silkworm Bombyx mori. IDENGAKU ZASSHI 1990; 65:401-10. [PMID: 2088426 DOI: 10.1266/jjg.65.401] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Abstract
In order to establish a transient expression system for genes introduced into early embryos of the silkworm, Bombyx mori, we tested various promoters ligated with CAT reporter genes. The embryos into which we injected supercoiled plasmid DNA of pFb(-860/+10)CAT containing the Bombyx fibroin promoter region ligated to the CAT gene showed a reasonably high CAT activity beginning around 30 h after oviposition. This high activity was observed only when the plasmid was injected before termination of the early nuclear cleavage stage, which was about 8 h after oviposition, but not after this stage. This means that the expression of injected DNA is closely related to the presence of cleavage nuclei in early embryos. Promoters originating from insect genes, like the Bombyx sericin-1 gene, Drosophila hsp70 and Drosophila copia LTR, functioned as strong promoters in the embryos. On the contrary, promoters from mammalian virus genes, such as the SV40 early and Moloney murine leukemia virus LTR genes, functioned as weak promoters. Moreover, linearized DNAs showed no or weak activity of expression in embryos. From these results, we conclude that the silkworm embryo transient expression system is a useful tool for studying the mechanism of regulation of insect genes.
Collapse
Affiliation(s)
- T Tamura
- National Institute of Sericultural and Entomological Science, Ibaraki
| | | | | | | | | |
Collapse
|
8
|
Hui CC, Matsuno K, Suzuki Y. Fibroin gene promoter contains a cluster of homeodomain binding sites that interact with three silk gland factors. J Mol Biol 1990; 213:651-70. [PMID: 2359119 DOI: 10.1016/s0022-2836(05)80253-0] [Citation(s) in RCA: 58] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
By nuclease protection and mobility shift assays, we have shown that the 5' flanking sequence of the Bombyx mori fibroin gene, which is known to be required for a maximal level of transcription in vitro, contains five regions (A to E) that bind protein factors from the posterior silk gland extract. A silk gland-specific factor (SGF-1) and a ubiquitous factor (FBF-A1) were found to interact with the proximal A region, while the related B region can only bind SGF-1. The three distal regions (C, D and E) bind one posterior silk gland-specific factor (SGF-2) and two ubiquitous factors (SGF-3 and -4). SGF-1 might play an important role in the expression of silk protein genes because it also binds to a similar site in the sericin-1 gene and potential SGF-1 binding sites can be found in two other silk protein genes of Bombyx mori and the fibroin gene of Antheraea yamamai. The three distal regions for SGF-2, -3 and -4 contain ten base-pairs of A + T-rich repeats that resemble the consensus binding site (TCAATTAAAT) of a number of homeodomain proteins. The TAAT motif in the core of these regions is shown to be important for the binding of these three proteins and, as described elsewhere, two Drosophila homeodomain proteins, ZEN (zerknüllt) and EVE (even-skipped). Interestingly, SGF-3 appears to be a Bombyx octamer binding protein and may also be involved in the regulation of the sericin-1 gene. The possibility that the fibroin gene and other silk protein genes may be a group of target genes for some members of the homeobox gene family is discussed.
Collapse
Affiliation(s)
- C C Hui
- Department of Developmental Biology, National Institute for Basic Biology, Okazaki, Japan
| | | | | |
Collapse
|
9
|
Hui CC, Suzuki Y. Homeodomain Binding Sites in the Promoter Region of Silk Protein Genes1. (Bombyx mori/fibroin gene/sericin-1 gene/homeobox proteins/transcription). Dev Growth Differ 1990. [DOI: 10.1111/j.1440-169x.1990.00263.x] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
|
10
|
Suzuki Y, Obara T, Takiya S, Hui CC, Matsuno K, Suzuki T, Suzuki E, Ohkubo M, Tamura T. Differential Transcription of the Fibroin and Sericin-1 Genes in Cell-Free Extracts1. (fibroin gene/sericin gene/differential transcription/nuclear extracts/Bombyx mori). Dev Growth Differ 1990. [DOI: 10.1111/j.1440-169x.1990.00179.x] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
|
11
|
cDNA structure and expression of bombyxin, an insulin-like brain secretory peptide of the silkmoth Bombyx mori. J Biol Chem 1989. [DOI: 10.1016/s0021-9258(18)83288-4] [Citation(s) in RCA: 78] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022] Open
|
12
|
Takiya S, Suzuki Y. Factors involved in preferential transcription of the fibroin gene. EUROPEAN JOURNAL OF BIOCHEMISTRY 1989; 179:1-9. [PMID: 2917553 DOI: 10.1111/j.1432-1033.1989.tb14513.x] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
Abstract
Transcription factors for class II genes from a tissue source, the posterior silk glands of Bombyx mori, were fractionated by stepwise elution on a phosphocellulose column into five fractions: A (0.04 M KCl flow through), A' (0.1 M KCl eluate), B (0.3 M KCl eluate), C (0.5 M KCl eluate) and D (1 M KCl eluate). The minimal requirement for reconstruction of accurate initiation of transcription of the fibroin gene, as well as of the adenovirus 2 major late promoter, was the combination of fractions A, B and D, suggesting that transcription factors from B. mori can recognize general signals of the promoters for class II genes and that basic transcription factors are conserved even in distantly diverged species of eukaryotes. To detect activities stimulating the transcription governed by the promoter of fibroin gene, each fraction was tested for its function by supplementing a basal amount of HeLa cell extract. When circular templates were used, stimulatory activities specific for the fibroin gene were detected in fraction D. This preferential transcription is composed of at least three activities; the first and the second dependent on the upstream elements and the third dependent on the sequence downstream from the TATA box. However, when linear templates were used the preference for the fibroin gene was apparently lost and transcription activation by fraction D became general.
Collapse
Affiliation(s)
- S Takiya
- Department of Developmental Biology, National Institute for Basic Biology, Okazaki, Japan
| | | |
Collapse
|