Two female-specific DSX proteins are encoded by the sex-specific transcripts of dsx, and are required for female sexual differentiation in two wild silkmoth species, Antheraea assama and Antheraea mylitta (Lepidoptera, Saturniidae)
Two female-specific DSX proteins are encoded by the sex-specific transcripts of dsx, and are required for female sexual differentiation in two wild silkmoth species, Antheraea assama and Antheraea mylitta (Lepidoptera, Saturniidae)
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DOI：
10.1016/j.ibmb.2010.06.008
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发表时间：
2010-09-01
影响因子：
3.8
通讯作者：
Nagaraju, J.
中科院分区：
文献类型：
--
作者：
Shukla, J. N.;Nagaraju, J.
双性（dsx）是果蝇性别决定级联中最底部的基因。dsx的前mrna剪接产生雄性和雌性特异性转录本，分别编码雄性和雌性特异性蛋白质。dsx同源物已在不同昆虫种中被鉴定出来（双翅目有很多，膜翅目有两个，鳞翅目只有一个）。在所有这些物种中，dsx前mrna的性别特异性剪接形式编码一种雄性和一种雌性特异性dsx蛋白，该蛋白调节负责性别特异性性状的下游靶基因。在本研究中，我们克隆并鉴定了两种柞蚕（Antheraea assama和Antheraea mylitta）的dsx同源物。家蚕（Bombyx mori）所属的家蚕科和家蚕科的分化时间估计在160.9年左右。有趣的是，这些野生蚕蛾性别特异性剪接的dsx前mrna产生多个剪接变体。根据它们的开放阅读框架（ORF）和概念翻译，两个雌性特异性蛋白（DSXF1和DSXF2）和一个雄性特异性蛋白（DSXM）可以在这两个蛾子中推断出来。在两组女性特异性转录本的ORF中存在或缺失15bp的片段导致产生两种不同的女性特异性DSX蛋白。性别特异性的DSX蛋白有共同的氨基末端序列，但有性别特异性的羧基末端。两种女性特异性DSX蛋白（DSXF1和DSXF2）具有共同的DNA结合域（DM域）和寡聚化域（OD域），仅在其末端c端相差21aa。通过dsRNA介导的基因敲除对A. assama中dsx转录本的功能分析，导致dsx蛋白的直接靶蛋白卵黄原蛋白和六聚蛋白基因的表达完全取消，性腺分化不规则，繁殖力和孵化率急剧下降。总之，这些结果表明雌性特异性DSX蛋白参与了雌性性别分化的过程。此外，在Aadsx和Amydsx的雌性特异性转录本中，第4外显子序列，特别是负责Bmdsx性别特异性剪接的PESS序列的保存，表明在蚕蛾中存在dsx同源物的性别特异性剪接的共同机制。据我们所知，这是首次报道存在多种剪接形式的dsx前mrna编码两种女性特异性dsx蛋白。(C) 2010 Elsevier Ltd.版权所有。
doublesex (dsx) is the bottom most gene of the sex-determination cascade of Drosophila melanogaster. The pre-mRNA of dsx splices to produce male- and female-specific transcripts which code for the male- and female-specific proteins, respectively. dsx homologues have been characterized from different (many in Diptera, two in Hypmenoptera and only one in Lepidoptera) insect species. Sex-specific splice forms of dsx pre-mRNA in all these species code for one male- and one female-specific DSX proteins, which regulate the downstream target genes responsible for sex-specific characters. In the present study we have cloned and characterized the dsx homologues from two saturniid silkmoths, Antheraea assama and Antheraea mylitta. The divergence time between Saturniidae and Bombycidae to which the domesticated silkworm, Bombyx mori belongs is estimated to be around 160.9 MY. Interestingly, the dsx pre-mRNA of these wild silkmoths sex-specifically splices to generate multiple splice variants. On the basis of their open reading frame (ORF) and conceptual translation, two female-specific (DSXF1 and DSXF2) and one male-specific (DSXM) proteins could be inferred, in both the moths. Presence or absence of a 15 bp stretch within the ORF of the two groups of female-specific transcripts resulted in the production of two distinct female-specific DSX proteins. The sex-specific DSX proteins have common amino-terminal sequence but sex-specific carboxy termini. The two female-specific DSX proteins (DSXF1 and DSXF2) share common DNA binding domain (DM domain) and oligomerization domain (OD domain) and differ only at their extreme C-termini by 21aa. Functional analysis of dsx transcripts in A. assama by dsRNA mediated knock-down resulted in complete abolition of expression of vitellogenin and hexamerin genes, the direct targets of the DSX proteins, irregular differentiation of gonads, and drastic reduction in fecundity and hatchability. Together, these results suggest the involvement of both the female-specific DSX proteins in the process of female sexual differentiation. Further, conservation of the 4th exon sequence, especially the PESS sequence responsible for the sex-specific splicing of Bmdsx in the femalespecific transcripts of Aadsx and Amydsx, indicated the existence of a common mechanism of sex-specific splicing of dsx homologues in silkmoths. To our knowledge this is the first report of existence of multiple splice forms of dsx pre-mRNA encoding two female-specific DSX proteins. (C) 2010 Elsevier Ltd. All rights reserved.