Abstract: 【Aim】 ENF peptides identified in Lepidoptera are structurally conserved and play similar roles in many physiological events, including development, immunity and stress response. It was reported that an ENF peptide from silkworm (Bombyx mori) referred to as paralytic peptide (PP) induces immune response through MAPK phosphorylation, whereas its molecular mechanism is still unclear. Our research aimed to investigate the signal pathways activated by PP. 【Methods】 The response of different insect cell lines to PP was evaluated by fluorescent quantitative PCR, and the BmE cell lines in response to PP were screened based on the phosphorylation level of p38 MAPK analyzed by Western blot under the induction of PP. Then inhibitors against a variety of signaling pathways were applied to the BmE cells to screen the molecules involved in signal transmission. 【Results】 The activity of PP in stimulating antimicrobial peptide (AMP) production in BmE cells was abrogated by PI3K inhibitor LY294002 or receptor tyrosine kinase inhibitor Genistein. Furthermore, the dynamic phosphorylation of Akt and certain plasma membrane protein with a molecular mass of 70 kDa in BmE cells and hemocytes was observed in the course of PP stimulation. 【Conclusion】 PP induces the expression of AMPs via PI3K/Akt signaling pathway, and Genisteinsensitive receptor tyrosine kinase is also involved in this immunological activity of PP.

Key words: Bombyx mori, immunity, paralytic peptide, antimicrobial peptide, MAPK, PI3K, receptor tyrosine kinase, signaling pathway