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Liu H, Xu J, Wang L, Guo P, Tang Z, Sun X, Tang X, Wang W, Wang L, Cao Y, Xia Q, Zhao P. Serpin-1a and serpin-6 regulate the Toll pathway immune homeostasis by synergistically inhibiting the Spätzle-processing enzyme CLIP2 in silkworm, Bombyx mori. PLoS Pathog 2023; 19:e1011740. [PMID: 37851691 PMCID: PMC10629668 DOI: 10.1371/journal.ppat.1011740] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/04/2023] [Revised: 11/07/2023] [Accepted: 10/07/2023] [Indexed: 10/20/2023] Open
Abstract
The Toll receptor signaling pathway is an important innate immune response of insects to pathogen infection; its extracellular signal transduction involves serine protease cascade activation. However, excessive or constitutive activation of the Toll pathway can be detrimental. Hence, the balance between activation and inhibition of the extracellular protease cascade must be tightly regulated to achieve favorable outcomes. Previous studies have shown that serpins-serine protease inhibitors-negatively regulate insect innate immunity by inhibiting extracellular protease cascade signaling. Although the roles of serpins in insect innate immunity are well described, the physiological mechanisms underlying their synergistic effects remain poorly understand. Here, we characterize the molecular mechanism by which serpin-1a and serpin-6 synergistically maintain immune homeostasis of the silkworm Toll pathway under physiological and pathological conditions. Through in vitro biochemical assays and in vivo bioassays, we demonstrate that clip-domain serine protease 2 (CLIP2), as the Toll cascade-activating terminal protease, is responsible for processing proSpätzle1 to induce the expression of antimicrobial peptides. Further biochemical and genetic analyses indicate that constitutively expressed serpin-1a and inducible serpin-6 synergistically target CLIP2 to maintain homeostasis of the silkworm Toll pathway under physiological and pathological conditions. Taken together, this study provides new insights into the precise regulation of Toll cascade activation signals in insect innate immune responses and highlights the importance and complexity of insect immune homeostasis regulation.
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Affiliation(s)
- Huawei Liu
- Integrative Science Center of Germplasm Creation in Western China (CHONGQING) Science City, Biological Science Research Center, Southwest University, Chongqing, China
- Key Laboratory for Germplasm Creation in Upper Reaches of the Yangtze River, Ministry of Agriculture and Rural Affairs, Chongqing, China
| | - Jiahui Xu
- Integrative Science Center of Germplasm Creation in Western China (CHONGQING) Science City, Biological Science Research Center, Southwest University, Chongqing, China
| | - Luoling Wang
- Integrative Science Center of Germplasm Creation in Western China (CHONGQING) Science City, Biological Science Research Center, Southwest University, Chongqing, China
| | - Pengchao Guo
- Integrative Science Center of Germplasm Creation in Western China (CHONGQING) Science City, Biological Science Research Center, Southwest University, Chongqing, China
- Key Laboratory for Germplasm Creation in Upper Reaches of the Yangtze River, Ministry of Agriculture and Rural Affairs, Chongqing, China
| | - Zhangchen Tang
- Integrative Science Center of Germplasm Creation in Western China (CHONGQING) Science City, Biological Science Research Center, Southwest University, Chongqing, China
| | - Xiaotong Sun
- Integrative Science Center of Germplasm Creation in Western China (CHONGQING) Science City, Biological Science Research Center, Southwest University, Chongqing, China
| | - Xin Tang
- Chongqing Key Laboratory of Chinese Medicine & Health Science, Chongqing Academy of Chinese Materia Medica, Chongqing College of Traditional Chinese Medicine, Chongqing, China
| | - Wei Wang
- Integrative Science Center of Germplasm Creation in Western China (CHONGQING) Science City, Biological Science Research Center, Southwest University, Chongqing, China
- Key Laboratory for Germplasm Creation in Upper Reaches of the Yangtze River, Ministry of Agriculture and Rural Affairs, Chongqing, China
| | - Lingyan Wang
- Integrative Science Center of Germplasm Creation in Western China (CHONGQING) Science City, Biological Science Research Center, Southwest University, Chongqing, China
- Key Laboratory for Germplasm Creation in Upper Reaches of the Yangtze River, Ministry of Agriculture and Rural Affairs, Chongqing, China
| | - Yang Cao
- Integrative Science Center of Germplasm Creation in Western China (CHONGQING) Science City, Biological Science Research Center, Southwest University, Chongqing, China
- Key Laboratory for Germplasm Creation in Upper Reaches of the Yangtze River, Ministry of Agriculture and Rural Affairs, Chongqing, China
| | - Qingyou Xia
- Integrative Science Center of Germplasm Creation in Western China (CHONGQING) Science City, Biological Science Research Center, Southwest University, Chongqing, China
- Key Laboratory for Germplasm Creation in Upper Reaches of the Yangtze River, Ministry of Agriculture and Rural Affairs, Chongqing, China
| | - Ping Zhao
- Integrative Science Center of Germplasm Creation in Western China (CHONGQING) Science City, Biological Science Research Center, Southwest University, Chongqing, China
- Key Laboratory for Germplasm Creation in Upper Reaches of the Yangtze River, Ministry of Agriculture and Rural Affairs, Chongqing, China
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Guo K, Dong Z, Zhang X, Chen Y, Li Y, Jiang W, Qin L, Zhang Y, Guo Z, Xia Q, Zhao P. Analysis of histomorphometric and proteome dynamics inside the silk gland lumen of Bombyx mori revealed the dynamic change of silk protein during the molt stage. Int J Biol Macromol 2023; 236:123926. [PMID: 36889618 DOI: 10.1016/j.ijbiomac.2023.123926] [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: 01/19/2023] [Revised: 02/18/2023] [Accepted: 02/28/2023] [Indexed: 03/08/2023]
Abstract
Silkworms spin different silks at different growth stages for specific purposes. The silk spun before the end of each instar is stronger than that at the beginning of each instar and cocoon silk. However, the compositional changes in silk proteins during this process are unknown. Consequently, we performed histomorphological and proteomic analyses of the silk gland to characterize changes from the instar end to the next instar beginning. The silk glands were collected on day 3 of third- and fourth-instar larvae (III-3 and IV-3) and the beginning of fourth-instar larvae (IV-0). Proteomic analysis identified 2961 proteins from all silk glands. Silk proteins P25 and Ser5 were significantly more abundant in III-3 and IV-3 than in IV-0, and many cuticular proteins and protease inhibitors increased significantly in IV-0 compared with III-3 and IV-3. This shift may cause mechanical property differences between the instar end and beginning silk. Using section staining, qPCR, and western blotting, we found for the first time that silk proteins were degraded first and then resynthesized during the molting stage. Furthermore, we revealed that fibroinase mediated the changes of silk proteins during molting. Our results provide insights into the molecular mechanisms of silk proteins dynamic regulation during molting.
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Affiliation(s)
- Kaiyu Guo
- Biological Science Research Center, Integrative Science Center of Germplasm Creation in Western China (CHONGQING) Science City, Southwest University, 400715 Chongqing, China; Key Laboratory for Germplasm Creation in Upper Reaches of the Yangtze River, Ministry of Agriculture and Rural Affairs, 400715 Chongqing, China; Engineering Laboratory of Sericultural and Functional Genome and Biotechnology, Development and Reform Commission, 400715 Chongqing, China
| | - Zhaoming Dong
- Key Laboratory for Germplasm Creation in Upper Reaches of the Yangtze River, Ministry of Agriculture and Rural Affairs, 400715 Chongqing, China; Engineering Laboratory of Sericultural and Functional Genome and Biotechnology, Development and Reform Commission, 400715 Chongqing, China
| | - Xiaolu Zhang
- Biological Science Research Center, Integrative Science Center of Germplasm Creation in Western China (CHONGQING) Science City, Southwest University, 400715 Chongqing, China; Key Laboratory for Germplasm Creation in Upper Reaches of the Yangtze River, Ministry of Agriculture and Rural Affairs, 400715 Chongqing, China; Engineering Laboratory of Sericultural and Functional Genome and Biotechnology, Development and Reform Commission, 400715 Chongqing, China
| | - Yuqing Chen
- Biological Science Research Center, Integrative Science Center of Germplasm Creation in Western China (CHONGQING) Science City, Southwest University, 400715 Chongqing, China
| | - Yi Li
- Biological Science Research Center, Integrative Science Center of Germplasm Creation in Western China (CHONGQING) Science City, Southwest University, 400715 Chongqing, China; Key Laboratory for Germplasm Creation in Upper Reaches of the Yangtze River, Ministry of Agriculture and Rural Affairs, 400715 Chongqing, China; Engineering Laboratory of Sericultural and Functional Genome and Biotechnology, Development and Reform Commission, 400715 Chongqing, China
| | - Wenchao Jiang
- Biological Science Research Center, Integrative Science Center of Germplasm Creation in Western China (CHONGQING) Science City, Southwest University, 400715 Chongqing, China; Key Laboratory for Germplasm Creation in Upper Reaches of the Yangtze River, Ministry of Agriculture and Rural Affairs, 400715 Chongqing, China; Engineering Laboratory of Sericultural and Functional Genome and Biotechnology, Development and Reform Commission, 400715 Chongqing, China
| | - Lixia Qin
- Biological Science Research Center, Integrative Science Center of Germplasm Creation in Western China (CHONGQING) Science City, Southwest University, 400715 Chongqing, China; Key Laboratory for Germplasm Creation in Upper Reaches of the Yangtze River, Ministry of Agriculture and Rural Affairs, 400715 Chongqing, China; Engineering Laboratory of Sericultural and Functional Genome and Biotechnology, Development and Reform Commission, 400715 Chongqing, China
| | - Yan Zhang
- Biological Science Research Center, Integrative Science Center of Germplasm Creation in Western China (CHONGQING) Science City, Southwest University, 400715 Chongqing, China; Key Laboratory for Germplasm Creation in Upper Reaches of the Yangtze River, Ministry of Agriculture and Rural Affairs, 400715 Chongqing, China; Engineering Laboratory of Sericultural and Functional Genome and Biotechnology, Development and Reform Commission, 400715 Chongqing, China
| | - Zhouguanrui Guo
- Biological Science Research Center, Integrative Science Center of Germplasm Creation in Western China (CHONGQING) Science City, Southwest University, 400715 Chongqing, China
| | - Qingyou Xia
- Key Laboratory for Germplasm Creation in Upper Reaches of the Yangtze River, Ministry of Agriculture and Rural Affairs, 400715 Chongqing, China; Engineering Laboratory of Sericultural and Functional Genome and Biotechnology, Development and Reform Commission, 400715 Chongqing, China
| | - Ping Zhao
- Biological Science Research Center, Integrative Science Center of Germplasm Creation in Western China (CHONGQING) Science City, Southwest University, 400715 Chongqing, China; Key Laboratory for Germplasm Creation in Upper Reaches of the Yangtze River, Ministry of Agriculture and Rural Affairs, 400715 Chongqing, China; Engineering Laboratory of Sericultural and Functional Genome and Biotechnology, Development and Reform Commission, 400715 Chongqing, China.
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POUM2 homeostasis regulates intimal remodeling and cells fate in the anterior silk gland of the silkworm. Int J Biol Macromol 2023; 225:715-729. [PMID: 36403768 DOI: 10.1016/j.ijbiomac.2022.11.135] [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: 07/22/2022] [Revised: 10/11/2022] [Accepted: 11/08/2022] [Indexed: 11/20/2022]
Abstract
Tissue/organ remodeling and cells fate determination play key roles in the life cycle of animals. However, they are still poorly understood in insects, especially in the silkworm. The anterior silk gland (ASG) of the silkworm is essential for the formation and performance of silk fibers, but the regulatory mechanism of ASG remodeling and cells fate determination is less known. Here we found that silencing of POUM2 caused shorter ASG length, intimal structural defects, silkworm spinning failure, and the resultant naked pupae death, but cells number was not affected. Cells staining showed that DNA endoreduplication was not affected in the ASG. Transmission electron microscopy and chitin staining showed cuticle proteins and chitin were greatly reduced in the ASG during the molting period. Transcriptional analysis showed the expression profiles of cuticle proteins and chitin synthase were similar to that of POUM2 during the molting period, and POUM2 down-regulation reduced the expression of cuticle proteins, chitin synthase, autophagy and apoptosis-related genes. While the phenotype resulting from POUM2 over-expression was similar to that of POUM2 down-regulation. Cells staining revealed marked cells apoptosis with cells number reduction and inhibition of DNA endoreduplication in the ASG. Transcriptional analysis showed the expression of autophagy and apoptosis-related genes, and some cuticle proteins and chitin synthase were significantly up-regulated. The results suggest that POUM2 homeostasis regulates ASG intimal remodeling and cells fate, thus affecting ASG development, silkworm spinning and metamorphosis. Our studies not only offer potential molecular targets for genetic improvement of silk performance and molecular breeding of the silkworm, but also provide new insights into POU factor-mediated tissue remodeling and cells fate determination in insects.
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