拟南芥Rab-H1b在细胞极性生长过程中介导高尔基体与质膜互作的机制研究

Interaction and cooperation between membrane bounded organelles are essential for cell development and functioning. Therefore, the molecular basis of the organelle interaction and the underlying regulatory mechanisms are of great interests to researchers in the field of life sciences. The Golgi apparatus plays a central role in membrane trafficking. Newly synthesized proteins and lipids from the endoplasmic reticulum (ER) are transported to the Golgi apparatus to be modified. Then these “cargo” components are sorted via trans Golgi network (TGN) and delivered to the plasma membrane (PM) or other intracellular organelles. Recently, plant scientists revealed that ER-synthesized cellulose synthases are assembled into cellulose synthase complex (CSC) in the Golgi apparatus, and delivery of CSC to the PM is dependent on the direct interaction between the Golgi apparatus and the PM. It has been shown that pauses of the Golgi apparatus at the CSC-insertion sites on the PM relies on integration of cortical microtubules. However, the regulatory mechanism of Golgi-PM interaction remains a mystery. This project will reveal the biological function of Golgi-PM interaction in plant cells, and dissect important roles of Rab-H1b in regulation of Golgi-PM interaction. The regulatory network of Golgi-PM interaction in response to the developmental and environmental signals will be investigated as well.

细胞中功能各异的不同细胞器之间存在密切的接触和相互协作，是胞内生命活动高效有序进行的保障。近年来，有关细胞器互作的方式、功能和机制的研究成为生命科学研究领域的重点和热点。高尔基体是细胞内大分子转运的枢纽，内质网中新合成的蛋白经高尔基体加工和分选后经TGN分泌到质膜行使其生理功能。植物细胞中纤维素合酶(CESA)在内质网合成后被运输到高尔基体中进行修饰并装配成纤维素合酶复合体(CSC)，然后运输到质膜上合成细胞壁的重要组分--纤维素。研究发现高尔基体通过与质膜互作直接分泌CSC到质膜上，然而其分子调控机制并不清楚。本项目拟利用CSC在胞质与质膜之间运输作为模式系统，揭示高尔基体与质膜互作的生物学功能，解析调控这两个膜性细胞器互作的关键因子Rab-H1b的分子作用机制，并在此基础上探讨植物细胞中生长发育信号和环境信号调节高尔基体和质膜互作的调控网络。

细胞中功能各异的不同膜性细胞器之间存在密切的接触和相互协作，是胞内生命活动高效有序进行的保障。高尔基体是细胞内大分子转运的枢纽，内质网中新合成的蛋白经高尔基体加工和分选后经TGN分泌到质膜行使其生理功能。植物细胞中纤维素合酶(CESA)在内质网合成后被运输到高尔基体中进行修饰并装配成纤维素合酶复合体(CSC)，然后运输到质膜上合成细胞壁的重要组分--纤维素。本项目主要研究纤维素合酶复合体（CSC）如何通过高尔基体与质膜互作靶向质膜以及小G蛋白在这一过程中的功能和调控机制。我们发现小G蛋白RabH1b参与了TGN介导CSC由高尔基体向质膜转运的生物学过程，鉴定了调控RabH1b活性的上游调控因子（RabGEFs）和下游效应子，为后续深入解析相关调控机制奠定了基础。此外，我们还解析了ROP小G蛋白通过直接作用于SNARE蛋白促进囊泡与质膜融合进而调控膜性细胞器互作的新机制。