Nuclear envelope dynamics in Hutchinson-Gilford progeria syndrome

哈钦森-吉尔福德早衰综合征的核膜动力学

• 批准号: 230841458
• 负责人: Professorin Dr. Karima Djabali
• 金额: --
• 依托单位: Munich School of BioEngineering
• 依托单位国家: 德国
• 项目类别: Research Grants
• 财政年份: 2012
• 资助国家: 德国
• 起止时间: 2011-12-31 至 2020-12-31
• 项目状态: 已结题
• 来源: https://gepris.dfg.de/gepris/projekt/230841458?language=en
• 关键词: Nuclear; envelope; dynamics; Hutchinson; Gilford

Hutchinson-Gilford progeria syndrome (HGPS, OMIM 176670) is a rare, premature aging disorder that leads to death at an average age of 14 years, as a result of myocardial infarction or stroke. Mutations in the LMNA gene are responsible for HGPS, which belongs to the family of laminopathies. The most common mutation associated with HGPS is a de novo heterozygous single base pair substitution at position G608G (GGC>GGT) within exon 11 of the LMNA gene. This mutation results in the deletion of 50 amino acids at the carboxyl-terminal tail of prelamin A; the truncated protein is referred to as progerin. Lamins help maintain the shape and stability of the nuclear envelope and are involved in the regulation of DNA replication and transcription. Progerin undergoes only some of the normal posttranslational modifications and remains permanently farnesylated. The toxicity of progerin has been attributed, in part, to its farnesyl moiety.During the first round of this application, we demonstrated that progerin elicits spatiotemporal deviations in mitotic processes, particularly the processes that are dependent on proper association with the nuclear envelope and nuclear pore distribution. We contributed important and crucial data to the increasing list of cellular, genomic and metabolic defects caused by progerin. Previous studies on progerin have assessed its localization and activity during interphase, our study followed progerin throughout its inevitable participation in mitosis, a phenomenon that has been remarkably ignored to date. Our approach unraveled significant and specific delays in the mitotic redistribution of several proteins (nuclear lamins, emerin, and SUN1), including the trapping of SUN1 in the ER at the last stages of mitosis and delayed recruitment of nuclear pores in the re-assembling NE in HGPS cells. These changes were accompanied by a substantial increase in chromatin lagging, which caused binucleated cells and genomic instability.Based on these observations, we hypothesized that the critical positioning of SUN1 at the nuclear envelope and its aberrant interaction with progerin are directly implicated in the generation of an abnormal nuclear membrane system in HGPS cells. This consequently leads to alterations in the nuclear shape, NPC positioning, cellular homeostasis and function that drive HGPS cells to undergo apoptosis and premature senescence. To test this hypothesis, we propose to investigate the following Specific Aims: (1) characterize progerin intracellular trafficking and nuclear envelope association; and (2) characterize progerin-SUN1 interaction and its inevitable consequences on nuclear pore distribution and nuclear integrity.

哈钦森-吉尔福德早衰综合征（HGPS, OMIM 176670）是一种罕见的早衰疾病，因心肌梗死或中风导致的平均死亡年龄为14岁。LMNA基因的突变是导致HGPS的原因，HGPS属于椎板病家族。与HGPS相关的最常见突变是在LMNA基因的第11外显子G608G （GGC>GGT）位置的新杂合单碱基对替换。该突变导致前纤层蛋白A羧基末端缺失50个氨基酸；截断的蛋白质被称为原蛋白。层粘连蛋白有助于维持核膜的形状和稳定性，并参与DNA复制和转录的调节。Progerin只经历一些正常的翻译后修饰，并保持永久的法尼化。progerin的毒性部分归因于它的法尼基部分。在第一轮应用中，我们证明了progerin在有丝分裂过程中引起时空偏差，特别是依赖于与核膜和核孔分布的适当关联的过程。我们为越来越多的由progerin引起的细胞、基因组和代谢缺陷提供了重要的数据。先前对progerin的研究已经评估了它在间期的定位和活性，我们的研究跟踪了progerin在有丝分裂中不可避免的参与，这一现象迄今为止被明显忽视。我们的方法揭示了几种蛋白质（核层蛋白、emerin和SUN1）在有丝分裂重新分配中的显著和特异性延迟，包括在有丝分裂的最后阶段，SUN1在内质网中的捕获，以及在HGPS细胞中重组NE时核孔的延迟募集。这些变化伴随着染色质滞后的大量增加，导致双核细胞和基因组不稳定。基于这些观察结果，我们假设SUN1在核膜上的关键位置及其与progerin的异常相互作用与HGPS细胞异常核膜系统的产生直接相关。这导致核形状、NPC定位、细胞稳态和功能的改变，从而导致HGPS细胞发生凋亡和过早衰老。为了验证这一假设，我们建议研究以下具体目的：(1)表征细胞内转运和核膜的关联；(2)描述progerin-SUN1相互作用及其对核孔分布和核完整性的必然影响。