Drosophila switch gene Sex-lethal can bypass its switch-gene target transformer to regulate aspects of female behavior
Drosophila switch gene Sex-lethal can bypass its switch-gene target transformer to regulate aspects of female behavior
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DOI：
10.1073/pnas.1319063110
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发表时间：
2013-11-19
影响因子：
11.1
通讯作者：
Cline, Thomas W.
中科院分区：
文献类型：
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作者：
Evans, Daniel S.;Cline, Thomas W.
开关基因性致死（Sxl）被认为通过仅控制开关基因变压器（tra）来引发果蝇雌性体细胞分化的所有方面，而不是大小二态性。在这里，我们证明 Sxl 通过作用于 tra 之外的目标来控制女性性行为的一个方面。我们通过观察到恢复 tra(-) 雌性生育能力的组成型女性化 tra 转基因未能恢复成年可存活但具有功能性 tra(-) 功能的 Sxl 突变雌性的生育能力，从而推断出这个未知 Sxl 靶标的存在。这些突变雌性的不育是由于排卵失败造成的。由于 tra 表达不足以使这些 Sxl 突变雌性具有生育能力，因此我们将此途径称为性别决定调节途径的 tra 女性化不足 (TIF) 分支。使用条件性表达两种 SXL 女性化亚型的转基因，我们发现 TIF 分支是神经元发育所必需的，这些神经元也特异性地表达无果的，一种控制性行为的 tra 基因目标。因此，在无果神经元的子集中，TIF 和 tra 通路的靶标似乎协同控制排卵。在大多数昆虫中，Sxl 没有性别特异性功能，tra（而不是 Sxl）既是主要性别信号的目标，也是通过积极的自动调节维持雌性发育承诺的基因。 TIF 通路可能代表了 Sxl 在成为果蝇 tra 调节因子的早期进化步骤中获得的祖先女性特异性功能。
The switch gene Sex-lethal (Sxl) was thought to elicit all aspects of Drosophila female somatic differentiation other than size dimorphism by controlling only the switch gene transformer (tra). Here we show instead that Sxl controls an aspect of female sexual behavior by acting on a target other than or in addition to tra. We inferred the existence of this unknown Sxl target from the observation that a constitutively feminizing tra transgene that restores fertility to tra(-) females failed to restore fertility to Sxl-mutant females that were adult viable but functionally tra(-). The sterility of these mutant females was caused by an ovulation failure. Because tra expression is not sufficient to render these Sxl-mutant females fertile, we refer to this pathway as the tra-insufficient feminization (TIF) branch of the sex-determination regulatory pathway. Using a transgene that conditionally expresses two SXL feminizing isoforms, we find that the TIF branch is required developmentally for neurons that also sex-specifically express fruitless, a tra gene target controlling sexual behavior. Thus, in a subset of fruitless neurons, targets of the TIF and tra pathways appear to collaborate to control ovulation. In most insects, Sxl has no sex-specific functions, and tra, rather than Sxl, is both the target of the primary sex signal and the gene that maintains the female developmental commitment via positive autoregulation. The TIF pathway may represent an ancestral female-specific function acquired by Sxl in an early evolutionary step toward its becoming the regulator of tra in Drosophila.