Department of Biology, Duke University, Durham, NC 27708, USA
Department of Biology, Duke University, Durham, NC 27708, USA.
Development. 2018 Mar 19;145(6):dev160101. doi: 10.1242/dev.160101.
The wing imaginal disks of Lepidoptera can be grown in tissue culture, but require both insulin and ecdysone to grow normally. Here, we investigate the contributions the two hormones make to growth. Ecdysone is required to maintain mitoses, whereas in the presence of insulin alone mitoses stop. Both ecdysone and insulin stimulate protein synthesis, but only ecdysone stimulates DNA synthesis. Insulin stimulates primarily cytoplasmic growth and an increase in cell size, whereas ecdysone, by virtue of its stimulation of DNA synthesis and mitosis, stimulates growth by an increase in cell number. Although both hormones stimulate protein synthesis, they do so in different spatial patterns. Both hormones stimulate protein synthesis in the inter-vein regions, but ecdysone stimulates synthesis more strongly in the veins and in the margin of the wing disk. We propose that the balance of insulin and ecdysone signaling must be regulated to maintain normal growth, and when growth appears to be due primarily to an increase in cell number, or an increase in cell size, this may indicate growth occurred under conditions that favored a stronger role for ecdysone, or insulin, respectively.
鳞翅目昆虫的翅原基组织可在组织培养中生长，但需要胰岛素和蜕皮激素才能正常生长。在这里，我们研究了这两种激素对生长的贡献。蜕皮激素对于维持有丝分裂是必需的，而在单独存在胰岛素的情况下，有丝分裂会停止。蜕皮激素和胰岛素都能刺激蛋白质合成，但只有蜕皮激素能刺激 DNA 合成。胰岛素主要刺激细胞质生长和细胞大小增加，而蜕皮激素通过刺激 DNA 合成和有丝分裂，通过增加细胞数量来刺激生长。尽管两种激素都能刺激蛋白质合成，但它们的作用模式不同。两种激素都能刺激脉间区域的蛋白质合成，但蜕皮激素更强烈地刺激脉和翅盘边缘的合成。我们提出，胰岛素和蜕皮激素信号的平衡必须受到调节，以维持正常的生长，当生长似乎主要是由于细胞数量的增加或细胞大小的增加时，这可能表明生长是在有利于蜕皮激素或胰岛素分别发挥更强作用的条件下发生的。
