Burtis K C, Coschigano K T, Baker B S, Wensink P C
Department of Genetics, University of California, Davis 95616.
EMBO J. 1991 Sep;10(9):2577-82. doi: 10.1002/j.1460-2075.1991.tb07798.x.
The doublesex (dsx) gene of Drosophila melanogaster encodes both male-specific and female-specific polypeptides, whose synthesis is regulated by alternative sex-specific splicing of the primary dsx transcript. The alternative splicing of the dsx mRNA is the last known step in a cascade of regulatory gene interactions that involves both transcriptional and post-transcriptional mechanisms. Genetic studies have shown that the products of the dsx locus are required for correct somatic sexual differentiation of both sexes, and have suggested that each dsx product functions by repressing expression of terminal differentiation genes specific to the opposite sex. However, these studies have not shown whether the dsx gene products function directly to regulate the expression of target genes, or indirectly through another regulatory gene. We report here that the male- and female-specific DSX proteins, expressed in E.coli, bind directly and specifically in vitro to three DNA sequences located in an enhancer region that regulates female-specific expression of two target genes, the yolk protein genes 1 and 2. This result suggests strongly that dsx is a final regulatory gene in the hierarchy of regulatory genes controlling somatic sexual differentiation.
黑腹果蝇的双性基因（doublesex，dsx）编码雄性特异性和雌性特异性多肽，其合成受初级dsx转录本的性别特异性可变剪接调控。dsx mRNA的可变剪接是一系列调控基因相互作用的最后已知步骤，这些相互作用涉及转录和转录后机制。遗传学研究表明，dsx基因座的产物是两性正确的体细胞性别分化所必需的，并表明每个dsx产物通过抑制异性特异性终末分化基因的表达来发挥作用。然而，这些研究尚未表明dsx基因产物是直接调节靶基因的表达，还是通过另一个调控基因间接调节。我们在此报告，在大肠杆菌中表达的雄性和雌性特异性DSX蛋白在体外直接且特异性地结合位于增强子区域的三个DNA序列，该增强子区域调节两个靶基因——卵黄蛋白基因1和2的雌性特异性表达。这一结果有力地表明，dsx是控制体细胞性别分化的调控基因层级中的最终调控基因。
