Yamanaka Naoki, Marqués Guillermo, O'Connor Michael B
Department of Genetics, Cell Biology and Development, University of Minnesota, Minneapolis, MN 55455, USA; Department of Entomology, Institute for Integrative Genome Biology, Center for Disease Vector Research, University of California, Riverside, Riverside, CA 92521, USA.
University Imaging Centers, University of Minnesota, Minneapolis, MN 55455, USA.
Cell. 2015 Nov 5;163(4):907-19. doi: 10.1016/j.cell.2015.10.022.
Steroid hormones are a large family of cholesterol derivatives regulating development and physiology in both the animal and plant kingdoms, but little is known concerning mechanisms of their secretion from steroidogenic tissues. Here, we present evidence that in Drosophila, endocrine release of the steroid hormone ecdysone is mediated through a regulated vesicular trafficking mechanism. Inhibition of calcium signaling in the steroidogenic prothoracic gland results in the accumulation of unreleased ecdysone, and the knockdown of calcium-mediated vesicle exocytosis components in the gland caused developmental defects due to deficiency of ecdysone. Accumulation of synaptotagmin-labeled vesicles in the gland is observed when calcium signaling is disrupted, and these vesicles contain an ABC transporter that functions as an ecdysone pump to fill vesicles. We propose that trafficking of steroid hormones out of endocrine cells is not always through a simple diffusion mechanism as presently thought, but instead can involve a regulated vesicle-mediated release process.
类固醇激素是一大类胆固醇衍生物，在动物和植物界中调节发育和生理功能，但关于它们从类固醇生成组织分泌的机制却知之甚少。在这里，我们提供证据表明，在果蝇中，类固醇激素蜕皮激素的内分泌释放是通过一种受调控的囊泡运输机制介导的。在类固醇生成的前胸腺中抑制钙信号会导致未释放的蜕皮激素积累，并且该腺体中钙介导的囊泡胞吐作用成分的敲低会由于蜕皮激素缺乏而导致发育缺陷。当钙信号被破坏时，在前胸腺中观察到突触结合蛋白标记的囊泡积累，并且这些囊泡含有一种作为蜕皮激素泵来填充囊泡的ABC转运蛋白。我们提出，类固醇激素从内分泌细胞中运输出来并不总是像目前所认为的那样通过简单的扩散机制，而是可能涉及一个受调控的囊泡介导的释放过程。
