Investigation of smooth muscle cell loss in progeria

 描述（由申请人提供）：Hutchinson-Gilford早衰综合征（HGPS）是一种毁灭性的早衰疾病。患有HGPS的儿童仅死于心脏病发作或中风，平均年龄为13岁。大多数HGPS病例是由核纤层蛋白A基因中的突变C1824 T引起的。这种突变激活了一个隐蔽的剪接位点，产生了一个截短的核纤层蛋白A突变体，称为早老蛋白。尚不清楚早老素如何导致HGPS患者危及生命的心血管疾病。先前的研究揭示了人类患者和HGPS小鼠模型中大动脉中平滑肌细胞（SMC）大量丢失的深刻表型，强烈表明这种表型与HGPS相关的心血管功能障碍和死亡有关。这项建议的主要目标是阐明这种表型背后的分子途径。基于我的小组最近的一项研究（Zhang et al.，PNAS 2014），我们假设一种机制，即早老蛋白的存在使聚[ADP-核糖]聚合酶1（PARP 1）蛋白不稳定，并导致非同源末端连接（NHEJ）（易错DNA修复途径）的激活。因此，错误修复的染色体在有丝分裂中遇到问题，导致HGPS SMC的有丝分裂灾难。在该提案中，我们建议通过以下方式来测试该想法：（i）阐明早老蛋白如何导致PARP 1下调，（ii）研究HGPS SMC中PARP 1破坏的后果，以及（iiI I）确定NHEJ的衰减是否可以减轻HGPS中的SMC损失。我们将使用HGPS患者特异性诱导多能干细胞（iPSC）在体外模拟SMC损失，以及应用HGPS小鼠模型来测试我们的假设在体内。

 DESCRIPTION (provided by applicant): Hutchinson-Gilford progeria syndrome (HGPS) is a devastating premature aging disease. Children with HGPS exclusively die of heart attacks or strokes at an average age of 13 years. The majority of HGPS cases are caused by a mutation C1824T in the lamin A gene. This mutation activates a cryptic splicing site and produces a truncated lamin A mutant named progerin. It is unknown how progerin causes the life-threatening cardiovascular diseases in HGPS patients. Previous research revealed a profound phenotype of massive loss of smooth muscle cells (SMCs) in large arteries in both human patients and HGPS mouse models, strongly suggesting a connection of this phenotype with the cardiovascular malfunction and death associated with HGPS. The primary goal of this proposal is to elucidate the molecular pathway behind this phenotype. Based on a recent study from my group (Zhang et al., PNAS 2014), we hypothesize a mechanism that the presence of progerin destabilizes Poly [ADP-ribose] polymerase 1 (PARP1) protein and leads to the activation of non-homologous end joining (NHEJ), the error-prone DNA repair pathway. Consequently, the mis-repaired chromosomes encounter problems in mitosis, which results in mitotic catastrophe of HGPS SMCs. In this proposal, we propose to test this idea by (i) elucidating how progerin lead to PARP1 down- regulation, (ii) studying the consequence of PARP1 disruption in HGPS SMCs, and (iiI) determining whether attenuation of NHEJ can alleviate SMC loss in HGPS. We will use HGPS patient specific induced pluripotent stem cells (iPSCs) to model SMC loss in vitro as well as apply mouse models of HGPS to test our hypothesis in vivo.