Lamin A Mutation and Hutchinson-Gilford Progeria

描述（由申请人提供）：Hutchinson-Gilford早衰综合征（HGPS）是一种具有早衰特征的疾病，由LMNA（编码核纤层蛋白A和C的基因）的显性从头突变引起，核纤层蛋白A和C是与核膜相关的中间丝蛋白。HGPS中的突变引入异常剪接位点，其导致核纤层蛋白A突变体的表达，其羧基末端附近缺失50个氨基酸。突变核纤层蛋白A被称为早老蛋白。核纤层蛋白A和核纤层蛋白C的不同突变导致心肌病和肌营养不良、部分脂肪营养不良综合征、周围神经病变和非典型Werner综合征。这些疾病中的一些与HGPS共享临床特征，而另一些则完全不同。核纤层蛋白A和C的突变如何导致HGPS或其他疾病尚不清楚。我们假设这些蛋白质的不同突变导致核结构和染色质组织的改变，从而导致基因表达异常。在HGPS中，早老蛋白表达，可能与正常核纤层蛋白A和C的表达减少相结合，是造成这一系列事件的原因。我们的目标是检验这个假设。目的1：研究早老素的生物化学及其对细胞核的影响。我们将确定是否早老蛋白，像正常的prelamin A，是法尼基化和处理的内蛋白水解。我们将研究早老蛋白对细胞核和染色质结构的影响，并使用荧光光漂白方法对其他核膜蛋白的动态。在目标2中，我们将产生在表皮中表达早老蛋白的转基因小鼠，并确定它们是否发展出与人类受试者HGPS皮肤和正常老化皮肤中的那些相似的病理和功能异常。我们还将早老蛋白转基因小鼠与杂合Lmna "敲除"小鼠杂交，以确定降低的野生型蛋白水平是否具有额外的影响。在目标3中，我们将确定法尼基转移酶抑制剂是否阻断早老蛋白的异戊烯化，并确定阻断早老蛋白异戊烯化是否逆转早老蛋白表达转基因小鼠中的细胞改变和组织异常，从而将目标1和2中的实验工作联系起来。该项目将确定核纤层蛋白A和C的突变如何导致HGPS，以及抑制蛋白法尼基化是否是一种潜在的治疗干预。

DESCRIPTION (provided by applicant): Hutchinson-Gilford progeria syndrome (HGPS), a condition with features of premature aging, is caused by a dominant de novo mutation in LMNA, the gene that encodes lamins A and C, intermediate filament proteins associated with the nuclear envelope. The mutation in HGPS introduces an abnormal splice site that leads the expression of a lamin A mutant with 50 amino acids deleted near its carboxyl-terminal end. The mutant lamin A has been called progerin. Different mutations in lamins A and C cause cardiomyopathy and muscular dystrophy, partial lipodystrophy syndromes, a peripheral neuropathy and atypical Werner syndrome. Some of these disorders share clinical features with HGPS while others are quite different. It is not known how mutations in lamins A and C cause HGPS or other diseases. We hypothesize that different mutations in these proteins cause alterations in nuclear structure and chromatin organization that lead to abnormalities in gene expression. In HGPS, progerin expression, possibly in combination with decreased expression of normal lamins A and C, is responsible for this chain of events. Our goal is to test this hypothesis. In Aim 1, we will study the biochemistry of progerin and its effects on the cell nucleus. We will determine if progerin, like normal prelamin A, is farnesylated and processed by endoproteolysis. We will investigate the effects of progerin on nuclear and chromatin structure and on the dynamics of other nuclear envelope proteins using fluorescent photobleaching methods. In Aim 2, we will generate transgenic mice expressing progerin in epidermis and determine if they develop pathological and functional abnormalities similar to those in skin of human subjects HGPS and normal aging skin. We will also cross progerin transgenic mice to heterozygous Lmna "knockout" mice to determine if reduced wild type protein levels have additional effects. In Aim 3, we will determine if a farnesyltransferase inhibitor blocks prenylation of progerin and determine if blocking progerin prenylation reverses cellular alterations and tissue abnormalities in progerin-expressing transgenic mice, hence connecting the experimental work in Aims 1 and 2. This project will establish how mutations in nuclear lamins A and C cause HGPS, and if inhibition of protein farnesylation is a potential therapeutic intervention.