Jindra Marek, Bellés Xavier, Shinoda Tetsuro
Biology Center, Czech Academy of Sciences, Branisovska 31, Ceske Budejovice 37005, Czech Republic.
Institute of Evolutionary Biology, CSIC-Universitat Pompeu Fabra, Passeig Marítim 37, 08003 Barcelona, Spain.
Curr Opin Insect Sci. 2015 Oct;11:39-46. doi: 10.1016/j.cois.2015.08.004. Epub 2015 Sep 2.
Despite important roles played by juvenile hormone (JH) in insects, the mechanisms underlying its action were until recently unknown. A breakthrough has been the demonstration that the bHLH-PAS protein Met is an intracellular receptor for JH. Binding of JH to Met triggers dimerization of Met with its partner protein Tai, and the resulting complex induces transcription of target genes. In addition, JH can potentiate this response by phosphorylating Met and Tai via cell membrane, second-messenger signaling. An important gene induced by the JH-Met-Tai complex is Kr-h1, which inhibits metamorphosis. Kr-h1 represses an 'adult specifier' gene E93. The action of this JH-activated pathway in maintaining the juvenile status is dispensable during early postembryonic development when larvae/nymphs lack competence to metamorphose.
尽管保幼激素（JH）在昆虫中发挥着重要作用，但其作用的潜在机制直到最近仍不为人知。一项突破是证明了bHLH-PAS蛋白Met是JH的细胞内受体。JH与Met的结合引发Met与其伙伴蛋白Tai的二聚化，形成的复合物诱导靶基因转录。此外，JH可通过细胞膜第二信使信号通路使Met和Tai磷酸化，从而增强这种反应。由JH-Met-Tai复合物诱导的一个重要基因是Kr-h1，它抑制变态。Kr-h1抑制“成虫决定因子”基因E93。当幼虫/若虫缺乏变态能力时，这条JH激活途径在胚胎后期发育早期维持幼虫状态的作用是可有可无的。
