Regulation of nuclear transport in disease

描述（由申请人提供）：核纤层结构成分的突变导致一系列人类疾病，称为核纤层病。纤层破裂如何产生细胞表型的具体机制尚未阐明。该提案测试了一个新的假设，即编码核纤层蛋白A的基因突变如何引起过早衰老疾病Hutchinson-Gilford早衰综合征（HGPS）的细胞表型。该提议基于显示以下的数据：（i）核质Ran梯度在HGPS患者细胞中被破坏，并且这可以在幼稚细胞中重现;（ii）Ran梯度破坏导致SUMO化酶Ubc 9从细胞核到细胞质的错误定位;（iii）降低活性氧物质的水平，其在HGPS细胞中升高，恢复RanGT α和Ubc 9的核定位。总体假设是，前核纤层蛋白A与核膜的组成性锚定产生活性氧物质，其抑制Ran GT系统，破坏Ran梯度，将Ubc 9重新定位于细胞质，并诱导早衰症中的细胞表型。因此，核纤层中的缺陷至少部分地通过核转运机制的变化被转导成细胞表型。在目标1中，我们将确定由早老蛋白诱导的活性氧的来源和机制。在目的2中，我们测试了Ran GTdR系统作为前核纤层蛋白A诱导的氧化应激的传感器的假设。在目的3中，我们测试的假设，SUMO结合酶Ubc 9作为氧化应激的效应器响应Ran梯度和调节基因表达的功能。我们的研究为早衰症领域带来了一个新的视角，其中包括一个基于信号传导和核转运的框架，以帮助理解疾病表型是如何在细胞水平上产生的。

DESCRIPTION (provided by applicant): Mutations in structural components of the nuclear lamina cause a spectrum of human diseases known as laminopathies. Specific mechanisms for how disruption of the lamina generates cellular phenotypes have not been elucidated. This proposal tests a new hypothesis for how mutation of the gene encoding lamin A gives rise to cellular phenotypes in the premature aging disease, Hutchinson-Gilford Progeria Syndrome (HGPS). The proposal is based on data showing (i) the nucleocytoplasmic Ran gradient is disrupted in HGPS patient cells and this can be recapitulated in naive cells; (ii) Ran gradient disruption causes mis-localization of the SUMOylation enzyme Ubc9 from the nucleus to the cytoplasm; (iii) Reducing the levels of reactive oxygen species, which are elevated in HGPS cells, restores nuclear localization of the RanGTPase and Ubc9. The overall hypothesis is that constitutive anchoring of pre-lamin A to the nuclear membrane generates reactive oxygen species that inhibit the Ran GTPase System, disrupt the Ran gradient, relocalize Ubc9 to the cytoplasm, and induce cellular phenotypes in Progeria. Thus, defects in the nuclear lamina are transduced into cellular phenotypes, at least in part, via changes in the nuclear transport machinery. In Aim 1 we will determine the source and mechanism of reactive oxygen species induction by Progerin. In Aim 2 we test the hypothesis that the Ran GTPase System acts as a sensor for pre-lamin A- induced oxidative stress. In Aim 3 we test the hypothesis that the SUMO conjugating enzyme Ubc9 functions as an effector of oxidative stress by responding to the Ran gradient and modulating gene expression. Our studies bring a new perspective to the Progeria field, which includes a signaling and nuclear transport-based based framework to help understand how disease phenotypes are generated at the cellular level.