Role for prelamin A in premature and physiological aging

项目总结 本项目旨在确定法尼化前层蛋白A在早熟和生理性衰老中的作用。 导致核支架蛋白前体前层蛋白A加工缺陷的基因突变 拉米素A，导致其法尼基修饰的持久性，并导致过早衰老障碍。最知名的 其中一种是Hutchinson-Gilford早衰症(HGPS)，在HGPS中，一种截短的法尼化前层蛋白A变体 被称为“孕激素”的表达。B型下颌骨发育不良(MAD-B)是一种相关疾病，其中 未经加工的法尼化前层素A本身在细胞中积累。一些证据表明，前层蛋白A也 在生理老化过程中积累。然而，法尼化的前层蛋白A在糖尿病中的作用机制 早衰障碍仍不清楚，其与生理性衰老的关系尚未得到证实。 经过严格的测试。我们假设前层蛋白A是骨质疏松症和心血管疾病的驱动因素 早衰或生理性衰老时发生的疾病。要具体检查 ，我们产生了一个新的小鼠品系(Lmna L648R/L648R)，它具有一个 锌金属蛋白酶ZMPSTE24使其失去作用的突变。这些小鼠只表达 前层蛋白A(没有成熟的层蛋白A)表现出严重的骨丢失，但寿命明显长于 其他衰老模型，因此是研究前层蛋白A在衰老过程中的作用的理想方法。在目标1中，我们将 确定前层蛋白A如何影响骨骼的数量、功能、发育、转录和信号转导 细胞，并将这些与生理衰老过程中发生的情况进行比较。我们还将评估这些老鼠是否 随着年龄的增长而发生血管疾病，或当与遗传基因结合时发展为加速的动脉粥样硬化 (低密度脂蛋白受体-/-)和高脂饮食干预，使小鼠对动脉粥样硬化敏感。在目标2中，我们将确定如何 前层蛋白A影响培养细胞并确定其促进相关细胞改变的机制(S) 为衰老干杯。我们将在培养细胞中进行时序转录分析，以确定最早的事件 由前层蛋白A促进，以区分因果变化和慢性反应。我们还将检验这一假设 Prelamin A诱导核膜破裂，从而刺激细胞质DNA传感器，导致 炎症的转录程序。我们将讲述从这些体外实验中获得的机械性见解。 Lmna L648R/L648R小鼠感染细胞的实验在目标3中，我们将确定前层蛋白A是否真的 通过检查幼年和老年小鼠的骨和血管组织，在生理老化过程中积累。我们会 还可以检测人体组织阵列和一组来自年轻人和老年人的成纤维细胞的前层蛋白A。 阐明前层蛋白A积聚的细胞机制和后果可能改变临床 以前层素A为基础的早衰障碍的治疗范例。更广泛地说，这一结果 Project可能严格地将Prelamin A与生理衰老联系在一起，确定它是一种潜在的治疗方法 针对与年龄相关的骨质疏松症、心血管疾病，以及可能的其他疾病。

PROJECT SUMMARY This project aims to define the role of farnesylated prelamin A in premature and physiological aging. Genetic mutations leading to defective processing of prelamin A, the precursor for the nuclear scaffold protein lamin A, result in persistence of its farnesyl modification and cause premature aging disorders. The best known of these is Hutchinson-Gilford progeria syndrome (HGPS), in which a truncated farnesylated prelamin A variant called “progerin” is expressed. Mandibuloacral dysplasia-type B (MAD-B) is a related disease, where unprocessed farnesylated prelamin A itself accumulates in cells. Some evidence suggests that prelamin A also accumulates during physiological aging. However, the mechanistic role of farnesylated prelamin A in premature aging disorders remains unclear, and its association with physiological aging has not been rigorously tested. We hypothesize that prelamin A is a driver of osteoporosis and cardiovascular disease that occurs in premature and possibly physiological aging. To specifically examine the consequences of prelamin A accumulation, we generated a novel mouse strain (LmnaL648R/L648R) with a mutation that abolishes its processing by the zinc metalloprotease ZMPSTE24. These mice express solely prelamin A (and no mature lamin A), exhibit profound bone loss, but have a significantly longer lifespan than other progeria models and are thus ideal to study the effects of prelamin A during aging. In Aim 1, we will determine how prelamin A affects the number, function, development, transcriptomes and signaling of bone cells, and compare these to what occurs in physiological aging. We will also assess whether these mice develop vascular disease as they age or develop accelerated atherosclerosis when combined with genetic (Ldlr-/-) and high-fat diet interventions that sensitize mice to atherosclerosis. In Aim 2, we will determine how prelamin A affects cultured cells and define the mechanism(s) by which it promotes cellular alterations related to aging. We will carry out chronological transcriptomic analyses in cultured cells to define the earliest events promoted by prelamin A to distinguish causal changes from chronic responses. We will also test the hypothesis that prelamin A induces nuclear envelope rupture that could stimulate a cytosolic DNA sensor and lead to a transcriptional program of inflammation. We will relate the mechanistic insights obtained from these in vitro experiments to affected cells in the LmnaL648R/L648R mice. In Aim 3, we will determine if prelamin A actually accumulates during physiological aging by examining bone and vascular tissue of young and old mice. We will also probe human tissue arrays and a panel of fibroblasts from young and aged individuals for prelamin A. Elucidating the cellular mechanisms and consequences of prelamin A accumulation could change clinical paradigms for the treatment of prelamin A-based premature aging disorders. More broadly, the results of this project could rigorously implicate prelamin A in physiological aging, identifying it as a potential therapeutic target for age-associated osteoporosis, cardiovascular disease, and possibly other ailments.