Regulation of Ecdysteroid Hormone Biosynthesis

9603547甲壳动物失去的四肢的生长、蜕皮和再生是由一对腺体(Y器官)的类固醇激素(蜕皮类固醇)控制的。反过来，Y器官又受到来自动物大脑的蛋白质荷尔蒙(MIH)的调节。这个系统类似于人类的腺体(睾丸、卵巢、肾上腺)，分泌类固醇激素(睾酮、雌激素、皮质醇)，由大脑和脑下垂体的蛋白质荷尔蒙控制。PI发现，甲壳类动物和人类一样，从胆固醇中产生类固醇激素，血液中的胆固醇与脂蛋白(HDL)结合在一起。因此，甲壳动物的腺体被用作研究胆固醇如何进入细胞，这些细胞如何将其转化为激素，以及这一过程如何受到大脑激素控制的简化模型。该项目的重点是如何将通胀从细胞表面转移到内部，最终转移到编码负责荷尔蒙合成的酶的基因上。细胞表面含有“识别”MIH和高密度脂蛋白的受体。特别是，信息信号是导致(A)膜酶的激活和(B)细胞内钙的释放的特殊脂类的假设将得到检验，这两个因素反过来又负责激活激素合成途径中的关键酶。问题的一个子集集中在这样一种可能性上，即循环中钙离子的增加以及细胞中已经存在的钙离子可能会触发激素合成的增加。方法包括使用放射性钙作为示踪剂和荧光指示剂来检测细胞内钙的释放。这项研究成果将有助于解开脊椎动物腺体的相关谜团。总体而言，这项研究有助于了解甲壳类及其昆虫近缘、经济上重要的动物群体的生物学知识，并涵盖神经生物学、内分泌学和发展领域，以解决神经内分泌协调和类固醇激素分泌控制的基本问题。***

9603547 Spaziani Growth, molting and regeneration of lost limbs in crustaceans is controlled by steroid hormones (ecdysteroids) from a pair of glands (Y-organs). The Y-organs, in turn, are regulated by a protein hormone (MIH) from the animals' brain. This system is comparable to human glands (testes, ovaries, adrenals) that secrete steroid hormones (testosterone, estrogen, cortisone) and that are controlled by protein hormones from the brain and pituitary gland. The PI has found that crustaceans, like humans, make steroid hormones from cholesterol and that the cholesterol in blood is bound up in lipoprotein (HDL). Accordingly, crustacean glands are being used as a simplified model to study how cholesterol enters cells, how those cells converted it to hormones, and how the process is controlled by the brain hormone. The project focuses on how inflation is transferred from the cell surface, which contains receptors that "recognize" MIH and HDL, to the interior, ultimately to genes that code for enzymes responsible for hormone synthesis. In particular, the hypothesis will be tested that informational signals are specialized lipids which cause (a) the activation of membrane enzymes, and (b) the release of intracellular calcium, both in turn responsible for activation of key enzymes in the path toward hormone synthesis. A subset of questions centers on the probability that increased hormone synthesis can be triggered by rises of calcium in the circulation as well as by calcium already resident in the cell. Methods include use of radioactive calcium as tracer and fluorescence indicators that detect release of intracellular calcium. The research results will help to solve related mysteries in vertebrate glands. Generally, this research contributes to knowledge of the biology of crustaceans and their insect relatives, economically important animal groups, and embraces the fields of neurobiology, endocrinology and development in addressing basic questions on neuroendocrine coordination and control of steroid hormone secretion. ***