Regulation of phosphoinositide lipid signalling and its function in determining organelle identity

从酵母到人类，真核细胞的特征是被称为细胞器的膜结合室。有许多细胞器类型，每一种都具有不同的生物物理、生化和功能特性。例如，内质网是由膜小管组成的迷宫，脂质和蛋白质在其中合成，而溶酶体是充满消化酶的小而圆的细胞器。有趣的是，细胞器不停地交换内容。因此，对细胞生物学家来说，一个非常重要的问题是细胞如何建立和维持各种类型的细胞器，换句话说，是什么决定了细胞器的身份？磷脂肌肽（PtdInsP）信号磷脂是细胞器身份的关键决定因素。有7种ptdinsp，每一种都表现出典型的细胞内分布和水平。特异的PtdInsP结合并招募同源蛋白效应物到膜上，然后赋予膜特定的功能。为了了解PtdInsP如何帮助确定细胞器身份，细胞生物学家需要了解合成和降解PtdInsP的酶是如何正确靶向和协调的，以及PtdInsP效应蛋白是如何工作的。我的实验室试图理解这些问题，以提高我们对细胞在我们体内如何运作的理解。在这里，我建议研究一种特殊的PtdInsP，磷脂酰肌醇-3,5-二磷酸[PI(3,5)P2]，它在后期内吞途径中控制细胞器的形态和膜交通。Vac14接头蛋白是一种支架蛋白，它与自身和其他四种PI(3,5)P2调节因子相互作用，包括分别合成和降解PI(3,5)P2的Fab1激酶和Fig4磷酸酶（Botelho et al. 2008）。目前的建议旨在提高我们对Vac14如何与这些其他蛋白质结合以控制PI(3,5)P2的理解。这一点很重要，因为PI(3,5)P2失调与神经退行性变有关，并与葡萄糖摄取有关。该建议可能为加拿大生物制药行业提供新的策略，以改善PtdInsP故障造成的条件，并减少其对受影响的加拿大人和加拿大经济的负面影响。

From yeast to human, eukaryotic cells are characterized by membrane-bound compartments called organelles. There are many organelle types, each with distinct biophysical, biochemical and functional properties. For example, the endoplasmic reticulum is a labyrinth of membrane tubules where lipid and protein synthesis occurs while lysosomes are small, round organelles full of digestive enzymes. Interestingly, organelles relentlessly exchange content. Therefore, a very important question for cell biologists is how do cells establish and maintain the various types of organelles - in other words, what determines organelle identity? The phosphoinositide (PtdInsP) signalling phospholipids are key determinants of organelle identity. There are seven PtdInsPs, each exhibiting a stereotypical intracellular distribution and levels. A specific PtdInsP binds and recruits cognate protein effectors to a membrane, which then endows that membrane with a specific function. In order to understand how PtdInsPs help to determine organelle identity, cell biologists need to understand both how the enzymes that synthesize and degrade PtdInsPs are properly targeted and coordinated as well as how PtdInsP effector proteins work. My laboratory seeks to understand these questions to improve our understanding of how cells function within our bodies. Here, I propose to study a specific PtdInsP, phosphatidylinositol-3,5-bisphosphate [PI(3,5)P2], which controls the morphology and membrane traffic of organelles in the late endocytic pathway. The Vac14 adaptor protein is a scaffolding protein that interacts with itself and four other PI(3,5)P2 regulators including the Fab1 kinase and the Fig4 phosphatase that synthesizes and degrades PI(3,5)P2, respectively (Botelho et al. 2008). The current proposal seeks to improve our understanding of how Vac14 interfaces with these other proteins to govern PI(3,5)P2. This is important since PI(3,5)P2 misregulation is associated with neurodegeneration and is linked to glucose uptake. This proposal may provide the Canadian biopharmaceutical industry with novel strategies to ameliorate conditions caused by PtdInsP malfunction and decrease its the negative impact on affected Canadians and the Canadian economy.