Zhang, J.; Zhang, X.; Zhang, H.; Li, J.; Li, W.; Liu, C. Overexpression of BmJHBPd2 Repressed Silk Synthesis by Inhibiting the JH/Kr-h1 Signaling Pathway in Bombyx mori. Int. J. Mol. Sci.2023, 24, 12650.
Zhang, J.; Zhang, X.; Zhang, H.; Li, J.; Li, W.; Liu, C. Overexpression of BmJHBPd2 Repressed Silk Synthesis by Inhibiting the JH/Kr-h1 Signaling Pathway in Bombyx mori. Int. J. Mol. Sci. 2023, 24, 12650.
Zhang, J.; Zhang, X.; Zhang, H.; Li, J.; Li, W.; Liu, C. Overexpression of BmJHBPd2 Repressed Silk Synthesis by Inhibiting the JH/Kr-h1 Signaling Pathway in Bombyx mori. Int. J. Mol. Sci.2023, 24, 12650.
Zhang, J.; Zhang, X.; Zhang, H.; Li, J.; Li, W.; Liu, C. Overexpression of BmJHBPd2 Repressed Silk Synthesis by Inhibiting the JH/Kr-h1 Signaling Pathway in Bombyx mori. Int. J. Mol. Sci. 2023, 24, 12650.
Abstract
Production of silkworm silk is the most economically important traits in the silk industry. Silk protein synthesis is regulated by juvenile hormone (JH) and 20-Hydroxyecdysone (20E). Therefore, it is important to understand the genetic regulation of silk production is thus a priority. JH binding protein (JHBP) transports JH from the hemolymph to target organs and cells and protects JH. In a previous study, we identified 41 genes containing a JHBP domain in the Bombyx mori genome. Only one JHBP gene, that is, BmJHBPd2, is highly expressed in the posterior silk gland (PSG) and its function remains unknown. In the present study, we investigated the expression levels of BmJHBPd2 and the major silk protein genes in the high silk-producing practical strain 872 (S872) and the low silk-producing local strain Dazao. Our results have shown that BmJHBPd2 was more highly expressed in S872, than in the Dazao strain, which is consistent with the expression pattern of fibroin genes. A subcellular localization assay indicated that BmJHBPd2 is located in the cytoplasm. In vitro hormone induction experiments showed that BmJHBPd2 was upregulated by treatment with juvenile hormone analogue (JHA). BmKr-h1 upregulation was significantly inhibited by overexpression of BmJHBPd2 at the cell level when induced by JHA. However, overexpression of BmJHBPd2 in the posterior silk gland by transgenic methods led to the inhibition of the expression of the silk fibroin gene, resulting in a reduction in silk yield. Further investigation has shown that in the BmJHBPd2OE individual, the key transcription factor Krüppel homolog 1 (Kr-h1) of the JH signaling pathway was inhibited, and 20E signaling pathway genes, such as broad complex (Brc), E74A, and ultraspiracle protein(USP), were upregulated. Our results have indicated that BmJHBPd2 plays an important role in the JH signaling pathway and was important for silk protein synthesis. Furthermore, our findings have helped to elucidate the mechanisms by which JH regulates silk protein synthesis.
Keywords
Juvenile hormone; Juvenile hormone binding protein; Silk protein; Bombyx mori
Subject
Biology and Life Sciences, Insect Science
Copyright:
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