Molecular Regulation and Transport of Sterols in Plants

植物甾醇是一系列复杂的化合物，对植物生长发育的许多方面都至关重要，对动物和人类的营养贡献也相当重要。因此，固醇生物合成途径的生物化学和分子生物学得到深入研究也就不足为奇了。然而，我们对植物中这一生化途径的调控知之甚少。角鲨烯合成酶是甾醇生物合成酶的关键酶，我们长期研究的目标之一是对角鲨烯合成酶的调控。我们最近的研究结果表明，角鲨烯合成酶的基因表达和酶活性定位于茎分生组织。在试图将这些结果与文献中已经报道的结果相一致时，最合乎逻辑的解释是甾醇生物合成本身定位于该组织。这一解释意味着甾醇生物合成的调节发生在茎分生组织中，这是一个以前没有被评估过的组织，并且甾醇运输系统必须存在，用于从顶端分生组织在整个植物中运动。提出了验证这些预测的实验，包括：1，评估定位于茎分生组织的甾醇生物合成是否受到调节；2、开发植物体内甾醇远距离运输试验；NPC1是一种高度保守的蛋白质，参与胆固醇摄取和细胞内运输，它在植物中是否扮演着与动物相似的角色。这项提议的工作将涉及本科生、研究生和博士后助理，应该为如何利用新兴技术设计这一途径以提高价值提供重要见解。

Plant sterols represent a complex array of chemical compounds that areessential for many facets of plant growth and development, and are ofconsiderable importance for their nutritional contributions to animals andman. Hence, it is not surprising that the biochemistry and molecularbiology of the sterol biosynthetic pathway has been intensively studied.Nonetheless, very little is actually known about the regulation of thisbiochemical pathway in plants. One goal of our long-term research in sterolmetabolism has been focussed on the regulation of squalene synthase, a keyenzyme in sterol biosynthetic enzyme. Our recent results suggest thatsqualene synthase gene expression and enzyme activity are localized toshoot meristems. In attempting to reconcile these results with thosealready reported in the literature, the most logical interpretation is thatsterol biosynthesis itself is localized to this tissue. This interpretationimplies that regulation of sterol biosynthesis occurs in the shootmeristem, a tissue that has not been evaluated as such before, and that asterol transport system for the movement of sterol from the apical meristemthroughout the plant must exist. Experiments to test these predictions areproposed and include: 1, an evaluation if sterol biosynthesis localized tothe shoot meristem is regulated; 2, the development of a test for longdistance transport of sterol within plants; and 3, a determination if NPC1,a highly conserved protein involved in cholesterol uptake and intracellulartrafficking, plays a similar role in plants as in animals. The proposedwork, which will involve undergraduate and graduate students and apostdoctoral associate, should provide important insights into how thispathway might be engineered for enhanced value using emerging technologies.