PI3K和受体型酪氨酸激酶介导家蚕麻痹肽免疫诱导信号的传递

【目的】普遍存在于鳞翅目昆虫中的ENF肽具有非常相似的结构和生理功能， 对昆虫的发育、 免疫、 应激反应等方面都起着重要的调控作用。有研究报道， 作为ENF肽家族成员之一的家蚕Bombyx mori麻痹肽（paralytic peptide, PP）通过激活MAPK来调控家蚕的免疫应答， 但其完整的分子作用机制尚不明确。本研究旨在解析传递家蚕PP免疫诱导信号的分子通路。【方法】首先通过荧光定量PCR检测了多种昆虫细胞系在PP诱导下抗菌肽基因的转录水平， 并利用Western blot检测p38 MAPK的磷酸化水平， 然后利用不同信号传递分子的抑制剂处理BmE细胞筛选参与传递PP免疫诱导信号的分子。【结果】PI3K抑制剂LY294002和受体型酪酸激酶抑制剂Genistein抑制了PP对BmE细胞抗菌肽基因表达的诱导作用； 且BmE细胞和家蚕血细胞在PP的诱导下， Akt和大小约为70 kDa的细胞膜蛋白均出现磷酸化水平的动态变化。【结论】PI3K/Akt信号通路和Genistein敏感性的受体型酪氨酸激酶介导了PP免疫诱导信号的传递。

Paralytic peptide activates innate immunity via PI3K and receptor tyrosine kinase in silkworm (Bombyx mori)

【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.