Regulation of nuclear transport in disease

描述（由申请人提供）：核层结构成分的突变引起一系列被称为层状病变的人类疾病。层的破坏如何产生细胞表型的具体机制尚未阐明。这一提议测试了一个新的假设，即编码层合蛋白a的基因突变如何引起早衰疾病哈钦森-吉尔福德早衰综合征（HGPS）的细胞表型。该建议基于以下数据：(1)HGPS患者细胞的核细胞质Ran梯度被破坏，这可以在初始细胞中重现；（ii） Ran梯度破坏导致SUMOylation酶Ubc9从细胞核错误定位到细胞质；（iii）降低HGPS细胞中升高的活性氧水平，恢复RanGTPase和Ubc9的核定位。总的假设是，前纤层蛋白A在核膜上的结构性锚定产生活性氧，抑制Ran GTPase系统，破坏Ran梯度，将Ubc9重新定位到细胞质中，并诱导早衰症的细胞表型。因此，核层中的缺陷至少部分通过核转运机制的改变被转导成细胞表型。在Aim 1中，我们将确定Progerin诱导活性氧的来源和机制。在Aim 2中，我们测试了Ran GTPase系统作为层合蛋白a前诱导氧化应激的传感器的假设。在Aim 3中，我们验证了SUMO偶联酶Ubc9通过响应Ran梯度和调节基因表达作为氧化应激效应因子的假设。我们的研究为早衰症领域带来了新的视角，其中包括一个基于信号和核转运的框架，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. PUBLIC HEALTH RELEVANCE: The nucleus is a membrane-enclosed organelle that contains DNA, the genetic material that provides the blueprint for making proteins and determining cellular function. The structure and function of the nucleus depends on an elaborate scaffold termed the nuclear lamina. Mutations in the proteins that form the nuclear lamina cause human diseases known as laminopathies. The goal of our research is to determine how mutation of lamin A (a major component of the nuclear lamina) gives rise to the premature aging disease, Hutchinson-Gilford Progeria Syndrome.