| Summary: | The silkworm <i>Bombyx mori</i> is an economically important insect, as it is the main producer of silk. Fibroin heavy chain (<i>FibH</i>) gene, encoding the core component of silk protein, is specifically and highly expressed in silk gland cells but not in the other cells. Although the silkworm <i>FibH</i> gene has been well studied in transcriptional regulation, its biological functions in the development of silk gland cells remain elusive. In this study, we constructed a CRISPRa system to activate the endogenous transcription of <i>FibH</i> in <i>Bombyx mori</i> embryonic (BmE) cells, and the mRNA expression of <i>FibH</i> was successfully activated. In addition, we found that <i>FibH</i> expression was increased to a maximum at 60 h after transient transfection of sgRNA/dCas9-VPR at a molar ratio of 9:1. The qRT-PCR analysis showed that the expression levels of cellular stress response-related genes were significantly up-regulated along with activated <i>FibH</i> gene. Moreover, the lyso-tracker red and monodansylcadaverine (MDC) staining assays revealed an apparent appearance of autophagy in <i>FibH</i>-activated BmE cells. Therefore, we conclude that the activation of <i>FibH</i> gene leads to up-regulation of cellular stress responses-related genes in BmE cells, which is essential for understanding silk gland development and the fibroin secretion process in <i>B. mori</i>.
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