Bell L R, Horabin J I, Schedl P, Cline T W
Department of Biology, Princeton University, New Jersey 08544.
Cell. 1991 Apr 19;65(2):229-39. doi: 10.1016/0092-8674(91)90157-t.
Sex-lethal is a binary switch gene that controls all aspects of Drosophila sexual dimorphism. It must be active in females and inactive in males. The on/off regulation reflects alternative RNA splicing in which full-length proteins are produced only in females. Here we investigate the role of Sxl in maintaining sexual pathway commitments. By ectopic expression of a female Sxl cDNA in transgenic male flies, we show that Sxl protein induces a rapid switch from male- to female-specific splicing. The ectopically expressed Sxl protein wil trans-activate an endogenous wild-type Sxl gene. This establishes a feedback loop in which Sxl proteins induce their own synthesis by directing the female-specific splicing of Sxl transcripts. We conclude that the female determined state is maintained by Sxl through positive autoregulation, while the male determined state is maintained by default.
性别致死基因是一种双态开关基因，它控制果蝇性别二态性的各个方面。它在雌性中必须是活跃的，而在雄性中是不活跃的。这种开/关调节反映了可变RNA剪接，其中全长蛋白质仅在雌性中产生。在这里，我们研究了Sxl在维持性别途径定向中的作用。通过在转基因雄蝇中异位表达雌性Sxl cDNA，我们表明Sxl蛋白诱导了从雄性特异性剪接到雌性特异性剪接的快速转变。异位表达的Sxl蛋白将反式激活内源性野生型Sxl基因。这建立了一个反馈环，其中Sxl蛋白通过指导Sxl转录本的雌性特异性剪接来诱导自身的合成。我们得出结论，雌性决定状态通过Sxl的正自调节得以维持，而雄性决定状态则默认维持。
