Bmgsb is involved in the determination of cell fate by affecting the cell cycle genes in the silk gland of Bombyx mori

Silk gland is the only organ of silkworm that can produce silk protein, which is a natural macromolecular protein complex and widely utilized in various fields such as biomaterials and biomedicine. The development of silk gland and the expression patterns of silk protein crucial for the silk industry. In this study, the function of a transcription factor Bmgsb was investigated with CRISPR/Cas9 and transgenic system. It was found that the homozygous individuals in the Bmgsb KO line experienced spinning failure and pupae death, the AMSG exhibited defects, and the ASG displayed abnormal curvature. These phenotypes were accompanied by increased DNA endoreplication and significantly upregulated expression of fibroin genes in the ASG. RT-qPCR results confirmed significant upregulation of cell cycle-related genes, including cyclin G and cyclin T in the Bmgsb KO line. Furthermore, ectopic expression of Bmgsb in the PSG weakened PSG curvature, inhibited DNA endoreplication, and downregulated the expression of fibroin genes. These findings strongly suggest that Bmgsb plays a crucial role in determining cell fate in the silk gland and regulating the expression of silk protein through the cyclin pathway. Our research provides a theoretical foundation for further studies on organ differentiation and have implications for the silk industry.