Lamin A biogenesis, processing and progeria

核纤层蛋白 A 的生物发生、加工和早衰

• 批准号: 7912046
• 负责人: Susan D. Michaelis
• 金额: $ 32.51万
• 依托单位: JOHNS HOPKINS UNIVERSITY
• 依托单位国家: 美国
• 财政年份: 2009
• 资助国家: 美国
• 起止时间: 2009-09-30 至 2012-04-30
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/7912046
• 关键词: Abnormal Cell; Acute; Address; Adverse effects; Aging; Aging-Related Process; Architecture; Area; Binding Proteins; Biochemical; Biogenesis; Biological; Biological Process; Biology; C-terminal; Cardiomyopathies; Cell Line; Cell Nucleus; Cells; Characteristics; Cleaved cell; Cysteine; Data; Detection; Disease; Dysplasia; Electron Microscopy; Enzymes; Event; Exhibits; Face; Failure; Farnesyl Transferase Inhibitor; Figs - dietary; Gene Targeting; Genes; Genetic; Genetic Transcription; Gold; HIV therapy; In Vitro; Knowledge; Label; Laboratories; Lamin Type A; Lamin Type B; Lead; Light; Link; Lipodystrophy; Location; Mammalian Cell; Maps; Measures; Mediating; Membrane; Metabolic; Metalloproteases; Methylation; Methyltransferase; Modeling; Modification; Molecular; Morphology; Muscular Dystrophies; Mutation; Nuclear; Nuclear Envelope; Nuclear Inner Membrane; Nuclear Localization Signal; Pathology; Pathway interactions; Physiologic pulse; Physiological; Play; Post-Translational Protein Processing; Premature aging syndrome; Process; Progeria; Proteins; Proteolysis; Research; Role; Series; Site; Structural Protein; Syndrome; Tail; Testing; Therapeutic; Toxic effect; Ursidae Family; Work; Yeasts; Zinc; base; disease phenotype; farnesylation; inhibitor/antagonist; insight; interest; lamin B receptor; normal aging; novel; prelamin A; prenylation; public health relevance; research study

DESCRIPTION (provided by applicant): This project focuses on the biogenesis of Lamin A, a critical structural component of the nuclear envelope. Surprisingly, recent studies have revealed that mutations in the gene encoding Lamin A result in a wide range of diseases called the "laminopathies" (encompassing cardiomyopathy, muscular dystrophy, lipodystrophy, and progeroid disorders), leading to a resurgence of interest in the biology of Lamin A. The Lamin A precursor, prelamin A, undergoes a series of post-translational processing events, including: 1) C- terminal CaaX modification (prenylation, proteolysis, and carboxyl methylation), followed by 2) an endoproteolytic cleavage event, mediated by the zinc metalloprotease ZmpSte24, that removes the CaaX- modified C-terminus to yield mature Lamin A. In previous years of this project, our laboratory discovered ZmpSte24 as a key enzyme in the biogenesis of yeast a-factor. From these findings this project has evolved to study the biogenesis of Lamin A in mammalian cells. The most severe laminopathy is the premature aging disorder Hutchinson-Gilford Progeria Syndrome (HGPS). Strikingly, there appears to be a direct link between defective Zmpste24-mediated endoproteolytic processing of prelamin A and progeroid diseases based on the findings that: 1) HGPS results from a mutation in which the ZmpSte24 cleavage site within Lamin A is deleted, and 2) the progeroid disorders mandibuloacral dysplasia (MAD) and restrictive dermopathy (RD) map to ZmpSte24. Thus, it appears that the persistently prenylated form of Lamin A that is present in HGPS or zmpste24-/- cells leads to accelerated aging pathologies. In this proposal we will define key cell biological aspects of Lamin A processing and address the role that a lack of processing plays in disease mechanisms. We will use molecular, cell biological, genetic, and biochemical approaches to address the following aims: Aim 1) determine the cellular location of Lamin A processing (nucleoplasmic vs. the cytosolic face of the ER); Aim 2) determine the fate of the cleaved C- terminal tail; Aim 3) determine the recognition sequences within prelamin A important for ZmpSte24 cleavage, and define how Zmpste24 cleaves prelamin A using purified enzyme; and Aim 4) investigate the molecular mechanisms by which failure to cleave the prelamin A tail leads to cellular and disease phenotypes. In particular we will test whether methylation may contribute to the toxicity of Lamin A in HGPS. The intriguing finding that progeroid diseases are caused by incomplete processing of prelamin A has underscored the importance of a comprehensive understanding of the entire processing pathway, which we address in this proposal. Our studies will provide insight into therapeutic options for progeroid disorders. The significance of this research is heightened by recent findings that inhibition of ZmpSte24-mediated processing of prelamin A may contribute to HIV therapy-induced side effects, and possibly to the mechanisms of normal aging. PUBLIC HEALTH RELEVANCE: Mutations in the nuclear structural protein Lamin A cause the premature aging disorder Hutchinson-Gilford Progeria Syndrome (HGPS) and a spectrum of diseases known as "laminopathies". This project addresses fundamental unanswered questions about Lamin A biology, including how it is processed within the cell and how abnormal processing can cause disease, as in HGPS. Our studies will provide insight into potential therapeutic options for premature aging disorders, and may also shed light on the mechanisms underlying the normal aging process.

描述（由申请人提供）：该项目的重点是核纤层蛋白A的生物发生，核被膜的关键结构组成部分。令人惊讶的是，最近的研究表明，核纤层蛋白A编码基因的突变导致了一系列广泛的疾病，称为“核纤层蛋白病”（包括心肌病，肌营养不良，脂肪营养不良和早衰症），导致对核纤层蛋白A生物学的兴趣重新抬头。核纤层蛋白A前体，前核纤层蛋白A，经历一系列翻译后加工事件，包括：1）C末端CaaX修饰（异戊二烯化、蛋白水解和羧基甲基化），随后2）由锌金属蛋白酶ZmpSte 24介导的内切蛋白水解切割事件，其去除CaaX修饰的C末端以产生成熟核纤层蛋白A。在该项目的前几年，我们的实验室发现ZmpSte 24是酵母a因子生物合成中的关键酶。从这些发现中，该项目已经发展到研究哺乳动物细胞中核纤层蛋白A的生物发生。最严重的核纤层蛋白病是过早衰老病症哈钦森-吉尔福德早衰综合征（HGPS）。引人注目的是，基于以下发现，在缺陷性Zmpste 24介导的前核层蛋白A的内蛋白水解加工与早老性疾病之间似乎存在直接联系：1）HGPS由其中核层蛋白A内的ZmpSte 24切割位点缺失的突变引起，以及2）早老性疾病下颌肢端发育不良（MAD）和限制性皮肤病（RD）映射到ZmpSte 24。因此，似乎存在于HGPS或zmpste 24-/-细胞中的核纤层蛋白A的持续异戊二烯化形式导致加速老化病理学。在这项提案中，我们将定义核纤层蛋白A加工的关键细胞生物学方面，并解决缺乏加工在疾病机制中发挥的作用。我们将利用分子生物学、细胞生物学、遗传学和生物化学的方法来解决以下目标：目的1）确定核纤层蛋白A加工的细胞定位（ER的核质相对于胞质面）;目的2）确定切割的C末端尾的命运;目的3）确定ZmpSte 24切割前层蛋白A的重要识别序列，并利用纯化的酶确定ZmpSte 24切割前层蛋白A的机制;和目的4）研究不能切割前层蛋白A尾导致细胞和疾病表型的分子机制。特别地，我们将测试甲基化是否可能导致核纤层蛋白A在HGPS中的毒性。这一有趣的发现，即早衰症是由前层蛋白A的不完全加工引起的，强调了全面了解整个加工途径的重要性，我们在本提案中对此进行了讨论。我们的研究将为早老性疾病的治疗选择提供深入的见解。最近的研究结果表明，抑制ZmpSte 24介导的前层蛋白A的加工可能有助于HIV治疗诱导的副作用，并可能导致正常衰老的机制，这一研究的意义得到了加强。 公共卫生相关性：核结构蛋白核纤层蛋白A的突变导致过早衰老障碍哈钦森-吉尔福德早衰综合征（HGPS）和一系列被称为“核纤层蛋白病”的疾病。该项目解决了有关核纤层蛋白A生物学的基本未回答的问题，包括它如何在细胞内加工以及异常加工如何导致疾病，如HGPS。我们的研究将为过早衰老疾病的潜在治疗选择提供深入见解，也可能揭示正常衰老过程的潜在机制。