Rideout Elizabeth J, Narsaiya Marcus S, Grewal Savraj S
Department of Biochemistry and Molecular Biology, University of Calgary, Calgary, Alberta, Canada.
Department of Cellular and Physiological Sciences, University of British Columbia, Vancouver, British Columbia, Canada.
PLoS Genet. 2015 Dec 28;11(12):e1005683. doi: 10.1371/journal.pgen.1005683. eCollection 2015 Dec.
Almost all animals show sex differences in body size. For example, in Drosophila, females are larger than males. Although Drosophila is widely used as a model to study growth, the mechanisms underlying this male-female difference in size remain unclear. Here, we describe a novel role for the sex determination gene transformer (tra) in promoting female body growth. Normally, Tra is expressed only in females. We find that loss of Tra in female larvae decreases body size, while ectopic Tra expression in males increases body size. Although we find that Tra exerts autonomous effects on cell size, we also discovered that Tra expression in the fat body augments female body size in a non cell-autonomous manner. These effects of Tra do not require its only known targets doublesex and fruitless. Instead, Tra expression in the female fat body promotes growth by stimulating the secretion of insulin-like peptides from insulin producing cells in the brain. Our data suggest a model of sex-specific growth in which body size is regulated by a previously unrecognized branch of the sex determination pathway, and identify Tra as a novel link between sex and the conserved insulin signaling pathway.
几乎所有动物的体型都存在性别差异。例如，在果蝇中，雌性比雄性体型更大。尽管果蝇被广泛用作研究生长的模型，但这种雌雄体型差异背后的机制仍不清楚。在这里，我们描述了性别决定基因transformer（tra）在促进雌性身体生长中的新作用。正常情况下，Tra仅在雌性中表达。我们发现雌性幼虫中Tra的缺失会减小体型，而雄性中Tra的异位表达会增加体型。尽管我们发现Tra对细胞大小有自主影响，但我们也发现脂肪体中Tra的表达以非细胞自主方式增加雌性体型。Tra的这些作用并不需要其唯一已知的靶标doublesex和fruitless。相反，雌性脂肪体中Tra的表达通过刺激大脑中胰岛素产生细胞分泌胰岛素样肽来促进生长。我们的数据提出了一种性别特异性生长模型，其中体型由性别决定途径中一个以前未被认识的分支调节，并将Tra确定为性别与保守的胰岛素信号通路之间的新联系。
