Yamanaka Naoki, Honda Naoko, Osato Noe, Niwa Ryusuke, Mizoguchi Akira, Kataoka Hiroshi
Department of Integrated Biosciences, Graduate School of Frontier Sciences, The University of Tokyo, Japan.
Biosci Biotechnol Biochem. 2007 Nov;71(11):2808-14. doi: 10.1271/bbb.70420. Epub 2007 Nov 7.
The regulatory mechanisms of ecdysteroidogenic P450 gene expression were investigated in the silkworm, Bombyx mori. Bommo-FMRFamide (BRFa), a neural suppressor of prothoracic gland (PG) activity, was found to suppress the expression of several P450 genes induced by prothoracicotropic hormone (PTTH) in the PG. A transcription inhibitor suppressed PTTH-induced expression of the P450 genes and the opposing effects of BRFa, while their short-term effects on ecdysteroidogenesis remained unchanged. This result suggests that the effects of these factors on the P450 gene transcripts become obvious on a longer time scale. Moreover, spontaneous expression of a P450 gene was observed in long-term PG culture, and was repressed by juvenile hormone. These results explain well the developmental fluctuation patterns of the P450 gene transcripts in the PG, indicating that multiple factors coordinate to regulate basal PG activity during insect development.
在家蚕中研究了蜕皮甾体生成性细胞色素P450基因表达的调控机制。发现家蚕FMRF酰胺（BRFa），一种前胸腺（PG）活性的神经抑制因子，可抑制PG中由促前胸腺激素（PTTH）诱导的几种P450基因的表达。一种转录抑制剂抑制了PTTH诱导的P450基因表达以及BRFa的相反作用，而它们对蜕皮甾体生成的短期作用保持不变。该结果表明，这些因子对P450基因转录本的影响在更长的时间尺度上变得明显。此外，在长期PG培养中观察到一种P450基因的自发表达，并被保幼激素所抑制。这些结果很好地解释了PG中P450基因转录本的发育波动模式，表明在昆虫发育过程中多种因子协同调节基础PG活性。
