Study on the physiological f unction of IGF-like peptides in insects

果蝇胰岛素样肽-6(DILP6)是家蚕胰岛素样生长因子样肽(BIGFLP)的类似物，根据其时空模式和蜕皮激素对基因表达的诱导作用，被认为是家蚕IGF样肽的同源基因。Dilp6突变体具有正常的幼虫大小，但成虫大小较小。这一突变体的表型在游荡阶段后通过在脂肪体中过表达Dilp6而被拯救，该基因在正常表达的地点和时间表达。这些观察结果，加上我们之前对BIGFLP的研究，强烈表明脂肪体衍生的IGF样肽是昆虫摄食后生长的常见调节因子。对BIGFLP在家蚕中表达的系统研究表明，BIGFLP在脑和性腺中也以阶段特异性的方式表达，提示该肽在家蚕发育调节中具有多效性。

Drosophila insulin-like peptide-6 (DILP6) was identified to be the counterpart of Bombyx IGF-like peptide (BIGFLP), based on its spatiotemporal pattern and ecdysteroid-inducibility of gene expression. The dilp6 mutant had a normal larval size but a smaller adult size. This phenotype of the mutant was rescued by dilp6 overexpression in the fat body after the wandering stage, where and when this gene is normally expressed. These observations, together with our previous study on BIGFLP, strongly suggest that fat body-derived IGF-like peptide is a common regulator of postfeeding growth in insects. A systematic survey of BIGFLP expression in Bombyx revealed that this peptide is also expressed in the brain and gonads in a stage-specific manner, suggesting pleiotropic actions of this peptide in the regulation of Bombyx development.