Cortical ER Biogenesis in Mammalian Cells

描述(申请人提供)：皮质内质网(CER)在体内许多重要的生理过程中起着关键作用，包括神经和肌肉。直到最近，CER似乎要么存在，要么不存在，这取决于细胞类型。这导致了一种传统的观点，即CER是一种静态的特化，存在于一些但不是大多数细胞中。现在，各种研究，包括我们实验室的工作，深刻地挑战了这一观点。他们提出--相反--许多动物细胞，如果不是大多数动物细胞，具有根据适当的生理需求动态大量产生CER的内在能力。这意味着存在广泛分布但仍不为人所知的触发CER生物发生和周转的核心机制。我们已经开发了第一个允许控制诱导皮质内质网(CER)的系统，并在这里建议利用它来剖析产生这种迷人但仍然鲜为人知的细胞器的亚细胞途径和分子机制。该系统需要控制二聚化含有CER蛋白C-末端的ER膜蛋白，如酵母Ist2p和哺乳动物STIM1，从而在各种正常情况下很少或没有CER的哺乳动物细胞中触发含有该蛋白的CER的增殖。发现这种机制，它产生的途径，以及涉及的分子逻辑是这项研究拨款的长期目标，将对细胞生物学的基本概念以及神经生理学和肌肉生理学等相关领域产生重大影响。

DESCRIPTION (provided by applicant): The cortical ER (cER) plays a critical role in many important physiological processes in the body, including in nerve and muscle. Until recently, cER seemed to be either present or absent, depending on the cell type. This has led to the traditional view that cER is a static specialization found in some but not most cells. Now a variety of studies, including work from our laboratory, profoundly challenge this view. They suggest that - to the contrary - many if not most animal cells have the inherent capacity to dynamically produce cER in copious quantities upon suitable physiologic demand. This implies the existence of broadly-distributed yet still unknown core machinery that triggers cER biogenesis and turnover. We have developed the first system that permits the controlled induction of cortical ER (cER) and propose here to utilize it to dissect the sub-cellular pathways and molecular mechanisms that produce this fascinating but still obscure organelle. The system entails controlled dimerization of ER membrane proteins bearing the C-terminal peptide from a cER protein, such as yeast Ist2p and mammalian STIM1, which triggers proliferation of cER containing this protein in various mammailian cells that normally have little or no cER. Discovering this machinery, the pathways it generates, and the molecular logic involved is the long-term goal of this research grant, and will have a major impact on fundamental concepts in cell biology and related areas of neurophysiology and muscle physiology, among others.