Kozopas K M, Samos C H, Nusse R
Howard Hughes Medical Insitute and Department of Developmental Biology, Stanford University School of Medicine, Stanford, California 94305-5323 USA.
Genes Dev. 1998 Apr 15;12(8):1155-65. doi: 10.1101/gad.12.8.1155.
The sexually dimorphic characteristics of the reproductive tract in Drosophila require that cells of the gonad and the genital disc be assigned sex-specific fates. We report here that DWnt-2, a secreted glycoprotein related to wingless, is a signal required for cell fate determination and morphogenesis in the developing male reproductive tract. Testes from DWnt-2 null mutant flies lack the male-specific pigment cells of the reproductive tract sheath and the muscle precursors of the sheath fail to migrate normally. However, other cell types of the testis are unaffected. DWnt-2 is expressed in somatic cells of the gonad throughout development, implicating it as a signal that can influence pigment cell fate directly. Indeed, the ectopic expression of DWnt-2 in females results in the appearance of male-specific pigment cells in otherwise morphologically normal ovaries. Thus, the presence of pigment cells is a sexually dimorphic trait that is controlled by DWnt-2 expression. DWnt-2 is also expressed in regions of the male genital disc and gonad, which we have identified as sites of contact with muscle precursor cells, suggesting that secreted DWnt-2 protein is a signal for the migration or attachment of these cells.
果蝇生殖道的性别二态性特征要求性腺和生殖盘的细胞被赋予性别特异性命运。我们在此报告，DWnt - 2是一种与无翅蛋白相关的分泌型糖蛋白，是发育中的雄性生殖道细胞命运决定和形态发生所需的信号。DWnt - 2基因敲除突变果蝇的睾丸缺乏生殖道鞘的雄性特异性色素细胞，鞘的肌肉前体细胞无法正常迁移。然而，睾丸的其他细胞类型未受影响。DWnt - 2在性腺的体细胞中整个发育过程都有表达，这表明它是一种可直接影响色素细胞命运的信号。实际上，在雌性果蝇中异位表达DWnt - 2会导致在形态正常的卵巢中出现雄性特异性色素细胞。因此，色素细胞的存在是一种受DWnt - 2表达控制的性别二态性特征。DWnt - 2也在雄性生殖盘和性腺的区域表达，我们已将这些区域确定为与肌肉前体细胞接触的部位，这表明分泌的DWnt - 2蛋白是这些细胞迁移或附着的信号。
