Molecular determinants specifying cellular polarity of ENHANCER OF PINOID

拟南芥PINOID基因增强子(ENP)突变导致表皮生长素转运蛋白PINI的极性完全反转。生长素运输的紊乱导致胚胎缺乏子叶。在成虫阶段，茎无花的盲端植株发育。我们的工作揭示了ENP，一个光致因子NPH3的同系物，与PINI精确地共定位。然而，具有可溶性蛋白质特征的ENP到达目的地的方式与跨膜蛋白PINI不同。我们的初步工作表明，ENP的BTB/POZ结构域是其极性定位所必需的，而C-末端可能具有PINI极性和/或生长素运输的功能。ENP显然是决定表皮细胞极性的关键因素。然而，调节其自身极性的分子机制仍然难以捉摸。了解ENP的极性和功能的一个主要关键在于它与其他细胞元件的相互作用。因此，本申请提出了一系列实验，用先进的手段研究ENP的细胞动力学、其结构域的意义以及相互作用因子的分析。

Mutation of the Arabidopsis thaliana gene ENHANCER OF PINOID (ENP) in pinoid mutant background leads to complete reversal of the polarity of the auxin transporter PINI in the epidermis. The disturbed auxin transport leads to embryos lacking cotyledons. In adult stages, plants with blind-ending stems lacking flowers develop. Our work has revealed that ENP, a homolog of the phototropic factor NPH3, is precisely co-localized with PINI. However, ENP, a protein with characteristics of soluble proteins, reaches its destination on a different way than PINI, a transmembrane protein. Our preliminary work shows, that the BTB/POZ domain of ENP is required for its polar localization whereas the C-terminal regions likely harbour functionality for PINI polarity and/or auxin transport. ENP is obviously a crucial factor required for epidermal cell polarity. However, the molecular mechanisms, which mediate its own polarity remain elusive. A major key to understand ENP polarity and function lies in its interactions with other cellular elements. Therefore, this application proposes a series of experiments, which investigate the cellular dynamics of ENP, the significance of its domains as well as the analysis of interactors by advanced means.