Regulation of nuclear transport in disease

描述(申请人提供)：核板结构成分的突变会导致一系列称为椎板病的人类疾病。破坏椎板如何产生细胞表型的具体机制尚未阐明。这项建议测试了一种新的假说，即编码lamin A的基因突变如何在早衰症Hutchinson-Gilford Progeria综合征(HGPS)中引起细胞表型。该建议基于的数据表明：(I)HGPS患者细胞的核质RAN梯度被破坏，这可以在幼稚细胞中重现；(Ii)RAN梯度破坏导致SUMO化酶Ubc9从核到细胞质的错误定位；(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，前层蛋白A的结构性锚定在核膜上产生的活性氧物种抑制了RAN GTP酶系统，破坏了RAN梯度，将Ubc9重新定位到细胞质，并诱导了早熟禾的细胞表型。因此，核膜中的缺陷至少部分地通过核运输机制的改变而转化为细胞表型。在目标1中，我们将确定Progerin诱导活性氧的来源和机制。在目标2中，我们测试了RAN GTPase系统作为前层粘连蛋白A诱导的氧化应激的传感器的假设。在目标3中，我们验证了相扑结合酶Ubc9通过响应RAN梯度和调节基因表达而作为氧化应激的效应因子的假设。我们的研究为Progeria领域带来了一个新的视角，其中包括一个基于信号和核运输的框架，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.