Nuclear envelope dynamics in Hutchinson-Gilford progeria syndrome

Hutchinson-Gilford早衰综合征（HGPS，OMIM 176670）是一种罕见的早衰性疾病，由于心肌梗死或中风，导致平均14岁的死亡。LMNA基因的突变是HGPS的原因，HGPS属于核纤层蛋白病家族。与HGPS相关的最常见突变是LMNA基因外显子11内G608 G位置处的从头杂合单碱基对取代（GGC>GGT）。这种突变导致在前核层蛋白A的羧基末端尾部缺失50个氨基酸;截短的蛋白质被称为早老蛋白。核纤层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。早老蛋白只经历一些正常的翻译后修饰，并保持永久的法尼基化。早老蛋白的毒性部分归因于其法呢基moiet.During第一轮的本申请，我们证明了早老蛋白eliminate时空偏差在有丝分裂过程中，特别是依赖于适当的关联与核膜和核孔分布的过程。我们为越来越多的由早老蛋白引起的细胞、基因组和代谢缺陷提供了重要和关键的数据。以前的研究早老蛋白评估其定位和活动在间期，我们的研究如下早老蛋白在整个不可避免地参与有丝分裂，一个现象，已被显着忽视的日期。 我们的方法揭示了几种蛋白质（核纤层蛋白，emerin和SUN 1）的有丝分裂再分配的显着和特定的延迟，包括在有丝分裂的最后阶段在ER中捕获SUN 1和延迟在HGPS细胞中重新组装NE的核孔的募集。这些变化伴随着大量增加的染色质滞后，这导致双核细胞和基因组instability.Based上的这些观察，我们推测，在核膜的关键定位SUN 1和其异常的相互作用与早老蛋白直接牵连在HGPS细胞的异常核膜系统的产生。 因此，这导致核形状、NPC定位、细胞内稳态和功能的改变，这些改变驱动HGPS细胞经历凋亡和过早衰老。为了验证这一假设，我们提出研究以下特定目的：（1）表征早老蛋白细胞内运输和核膜缔合;（2）表征早老蛋白-SUN 1相互作用及其对核孔分布和核完整性的必然后果。

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.