Apical protein sorting in renal epithelial cells

描述(由申请人提供)：肾脏细胞的功能需要维持极化的质膜结构域，具有不同的蛋白质和脂肪成分，而蛋白质的适当靶向缺陷会导致疾病。尽管细胞极性在维持肾脏功能中起着关键作用，但我们对选择性地将蛋白质引导到顶端和基底外侧细胞表面的机制知之甚少。我们的长期目标是了解蛋白质是如何被分离并定位到肾脏细胞的顶端表面，目的是操纵蛋白质分选来治疗疾病。根尖分选信号多样，存在多种生物合成途径通向根尖质膜。在这里，我们提出了一个统一的顶端蛋白分选模型，在该模型中，分选室内的货物聚集提供了招募表面递送所需的膜和细胞质蛋白所需的亲和力。我们将使用一种在肾脏功能中起关键作用的蛋白质来测试这一模型，该蛋白质以糖依赖的方式靶向顶端表面。我们建议的研究利用前沿的生物物理、生化和蛋白质组学方法，并充分利用匹兹堡大学在肾上皮细胞生物学方面的独特设施和广泛的专业知识。这项工作将显著提高我们对肾脏如何维持心尖分类和极性的理解，并阐明操纵蛋白质运输以获得治疗优势的新策略。

DESCRIPTION (provided by applicant): Kidney cell function requires the maintenance of polarized plasma membrane domains with distinct protein and lipid compositions, and defects in proper targeting of proteins results in disease. Despite the critical role of cell polarity in maintaining kidney function, we know little about the mechanisms that selectively guide proteins to the apical and basolateral cell surfaces. Our long term goal is to understand how proteins are segregated and targeted to the apical surface of kidney cells with the objective of manipulating protein sorting to treat disease. Apical sorting signals are diverse and multiple biosynthetic routes exist to the apical plasma membrane. Here we propose a unifying model for apical protein sorting in which cargo clustering within sorting compartments provides the avidity necessary to recruit membrane and cytoplasmic proteins required for surface delivery. We will test this model using a protein with an essential role in kidney function that is targeted to the apical surface in a glycan dependent manner. Our proposed studies utilize cutting edge biophysical, biochemical, and proteomic approaches and take full advantage of the unique facilities and broad expertise in renal epithelial cell biology at the University of Pittsburgh. Ths work will significantly enhance our understanding of how apical sorting and polarity are maintained in the kidney and illuminate new strategies to manipulate protein traffic for therapeutic advantage.