Nucleocytoplasmic transport: a target for cellular control

描述(申请人提供)：核间和细胞质间交换的唯一媒介是核孔复合体(NPC)，由称为核孔蛋白或NUP的蛋白质组成。核质运输是由可溶性运输因子驱动的(大多数属于被称为核粘素或KAP的相关蛋白质家族)，它们携带同源货物穿过鼻咽癌。这种运输受到多个层面的调控，包括核粘附素对货物的识别以及与NPC的相互作用。NPC还通过影响核结构和作为各种核过程的控制点，在基因表达方面发挥关键调节作用。主要的病理细胞过程与核质运输的改变有关，许多病毒针对核质运输途径的组件来篡夺它。因此，核孔素和转运因子是药物治疗的关键潜在靶点。我们将专注于核质运输的两个关键调控领域，在这些领域，结构信息最有可能导致对这些调控过程的基本机械性见解。首先，我们将调查KAP如何识别他们的货物。KAPS重叠的特异性使细胞能够选择性地控制数千种货物的运输，并为药物干预提供了丰富的潜在靶点。PSI Biology将提供与其货物绑定的KAP的晶体结构，这将补充生化和生物信息学方法，以揭示货物识别的序列和结构要求。第二，我们将以高分辨率绘制NPC的篮子区域，这是一系列令人眼花缭乱的核进程的关键控制点。这些过程是由篮子蛋白之间相互作用的相互作用所调节的；然而，将这些不同的功能分配给篮子蛋白的结构域在很大程度上是不成功的，主要是因为人们对其结构组织和其组成部分的相互依赖知之甚少。因此，PSI Biology篮子组件及其相互作用的原子结构将与我们关于与NPC相关的选定亚复合体的补充生物物理、形态和蛋白质组学数据相结合，以获得NPC和核外围背景下的核篮子的高分辨率地图。一旦建立，这一图将被用来指导对单个组件的解剖和扰动，以阐明篮子的结构组织与其执行其各种功能的机制之间的关系。 与公共卫生相关：主要的病理细胞过程与运输材料进出细胞核的路径的恶性变化有关。该项目承诺在原子尺度上描述核运输路径的关键区域，以发现潜在的药物靶标。这最终将打开控制核运输的新疗法的大门，要么是为了阻止篡夺这些途径的病毒，要么是为了纠正这些途径中导致发育或致癌疾病的缺陷。

DESCRIPTION (provided by applicant): The sole mediators of exchange between the nuclear and cytoplasmic compartments are nuclear pore complexes (NPCs), comprised of proteins termed nucleoporins or Nups. Nucleocytoplasmic transport is driven by soluble transport factors (most belonging to a related family of proteins termed karyopherins or Kaps) that carry their cognate cargos across the NPC. This transport is regulated at multiple levels, including cargo recognition by karyopherins and interactions with the NPC. The NPC also plays a key regulatory role in gene expression by influencing nuclear architecture and acting as a point of control for various nuclear processes. Major pathological cellular processes are associated with altered nucleocytoplasmic transport, and many viruses target components of the nucleocytoplasmic transport pathway to usurp it. Hence, nucleoporins and transport factors are key potential targets for drug therapy. We will focus on two of the key regulatory areas of nucleocytoplasmic transport, where structural information is most likely to lead to fundamental mechanistic insights into these regulatory processes. First, we will investigate how Kaps recognize their cargos. The overlapping specificity of Kaps endows cells with the ability to selectively control the transport of thousands of cargos and provides a rich source of potential targets for pharmacological intervention. PSI Biology will provide crystal structures of Kaps bound to their cargos, which will complement biochemical and bioinformatics approaches to reveal both the sequence and structure requirements for cargo recognition. Second, we will map at high resolution the basket region of the NPC, a critical point of control for a bewildering array of nuclear processes. These processes are mediated by the interplay of interactions among the basket proteins; however, assigning these varied functions to domains of the basket proteins has proven largely unsuccessful, primarily because little is known about its structural organization and the interdependence of its components. The atomic structures of basket components and their interactors from PSI Biology will therefore be integrated with our complementary biophysical, morphological, and proteomic data on selected subcomplexes associated with the NPC to obtain a high resolution map of the nuclear basket in the context of the NPC and nuclear periphery. Once established, this map will be used to guide the dissection and perturbation of individual components, to elucidate the relationship between the structural organization of the basket and the mechanisms by which it executes its various functions. PUBLIC HEALTH RELEVANCE: Major pathological cellular processes are associated with malign alterations in the pathways that transport materials to and from the cell's nucleus. This project promises to characterize key areas of the nuclear transport pathways at the atomic scale, to discover potential drug targets. This will ultimately open the door to new therapies to control nuclear transport, either to thwart viruses that are usurping these pathways or to correct defects in these pathways that result in developmental or oncogenic diseases.