Protein Prenylation and Progeria

蛋白质异戊二烯化和早衰症

• 批准号: 7748017
• 负责人: Loren Gi Fong
• 金额: $ 38.5万
• 依托单位: UNIVERSITY OF CALIFORNIA LOS ANGELES
• 依托单位国家: 美国
• 财政年份: 2009
• 资助国家: 美国
• 起止时间: 2009-01-01 至 2013-12-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/7748017
• 关键词: Address; Affect; Alleles; Alopecia; Amino Acids; Antibodies; Biochemical; Biogenesis; Birth; Boxing; Breeding; C-terminal; Cell Nucleus; Cells; Cessation of life; Child; Cleaved cell; Clip; Cultured Cells; Cysteine; Defect; Development; Disease; Employee Strikes; Exhibits; Farnesyl Transferase Inhibitor; Fibroblasts; Figs - dietary; Fracture; Frequencies; Gene Targeting; Genes; Goals; Growth; Hand; Heterozygote; Human; Knock-in Mouse; Knowledge; Laboratories; Lamin Type A; Lamins; Lead; Left; Lipodystrophy; Lonafarnib; Lytic Metastatic Lesion; Mechanics; Metabolism; Methylation; Micrognathism; Modeling; Mus; Mutation; Normal Cell; Nuclear; Nuclear Inner Membrane; Nuclear Lamina; Osteoporosis; Pathogenesis; Pharmaceutical Preparations; Phenotype; Physiological; Physiology; Post-Translational Protein Processing; Premature aging syndrome; Process; Production; Progeria; Property; Protein Farnesylation; Protein Geranylgeranylation; Protein Isoprenylation; Proteins; Public Health; RNA Splicing; Relative (related person); Research; S-farnesylcysteine alpha-carboxyl methyl ester; Severities; Shapes; Site; Structural Protein; Syndrome; Techniques; Tertiary Protein Structure; Testing; Therapeutic Agents; Therapeutic Intervention; Time; Tissues; Toxic effect; Weight Gain; Western Blotting; bone; cell type; design; disease phenotype; falls; farnesylation; improved; in vivo; inhibitor/antagonist; interest; lamin C; mouse model; mutant; novel therapeutic intervention; prelamin A; premature; prevent; public health relevance; therapy development

DESCRIPTION (provided by applicant): Several progeroid disorders, including Hutchinson-Gilford progeria syndrome (HGPS), are caused by defects that lead to the accumulation of farnesyl-prelamin A at the nuclear rim. The accumulation of farnesyl-prelamin A causes grossly misshapen nuclei in cultured cells. We proposed that the farnesylated form of prelamin A is toxic to cells and predicted that inhibiting protein farnesylation would reduce the frequency of misshapen nuclei and ameliorate disease phenotypes in a pair of progeria mouse models created in our laboratory, Zmpste24-deficient mice and mice heterozygous for a HGPS "knock-in" mutation (LmnaHG/+). These predictions regarding the importance of protein farnesylation were upheld: farnesyltransferase inhibitors (FTIs) reduced the frequency of misshapen nuclei in cultured cells and also ameliorated disease phenotypes in both of the progeria mouse models. These studies have been gratifying because they have suggested that FTIs could be efficacious for treating humans with HGPS. However, these studies left us with important questions regarding the mechanisms by which FTIs improve disease phenotypes. The FTI treatment was unequivocally efficacious in ameliorating disease phenotypes, yet it had only a small effect on prelamin A processing in mice. How, therefore, can an improvement in disease phenotypes be explained? One possibility is that an extremely small effect on prelamin A farnesylation is sufficient to ameliorate disease phenotypes; another is that FTIs could ameliorate disease independently of their effect on prelamin A processing. Our first aim will be to examine this issue in detail, by analyzing additional gene-targeted mouse models and by better defining the effects of FTIs on prelamin A metabolism in vivo. Our second aim will be to further examine an unexpected finding in our HGPS mice-that the nuclear shape abnormalities and disease phenotypes associated with the LmnaHG allele can be reduced significantly by decreasing the synthesis of wild-type lamin A (by replacing the wild-type Lmna allele in the LmnaHG/+ mice with a "lamin C-only" allele). One interpretation of this finding is that wild-type prelamin A (or lamin A) worsens progeria, while lamin C does not. During the next few years, we will examine this concept in considerable detail by examining the impact of the LmnaHG allele in the presence of both a "lamin C-only" allele and a "lamin A-only" allele on disease phenotypes and nuclear mechanics. Our third aim will explore the physiological impact of nonfarnesylated prelamin A. Treatment of progeria with an FTI will lead to the accumulation of nonfarnesylated prelamin A (from the wild-type Lmna allele). The properties of this abnormal protein and whether it exhibits its own toxicities are unknown. We will address this issue by analyzing nonfarnesylated prelamin A-only mice and examining the impact of the lamin protein on cell and tissue physiology. PUBLIC HEALTH RELEVANCE The proposed studies will define how mutations in structural proteins of the nucleus cause premature aging, or progeria. New mouse models will be created to study the development of disease and to test a new therapeutic approach.

描述（由申请人提供）：几种早衰症，包括Hutchinson-Gilford早衰综合征（HGPS），是由导致法尼基-前核层蛋白A在核边缘积聚的缺陷引起的。法尼基-前核层蛋白A的积累导致培养细胞中的细胞核严重畸形。我们提出，前核层蛋白A的法尼基化形式对细胞有毒，并预测抑制蛋白法尼基化将降低我们实验室中创建的一对早衰小鼠模型（Zmpste 24缺陷小鼠和HGPS“敲入”突变杂合小鼠（LmnaHG/+））中畸形核的频率并改善疾病表型。这些关于蛋白质法尼基化的重要性的预测得到了支持：法尼基转移酶抑制剂（FTIs）降低了培养细胞中畸形细胞核的频率，并改善了两种早衰症小鼠模型中的疾病表型。这些研究是令人满意的，因为它们表明FTIs可以有效地治疗人类HGPS。然而，这些研究给我们留下了关于FTI改善疾病表型的机制的重要问题。FTI治疗在改善疾病表型方面是明确有效的，但它对小鼠中的前层蛋白A加工只有很小的影响。因此，如何解释疾病表型的改善？一种可能性是对前层蛋白A法尼基化的极小影响足以改善疾病表型;另一种可能性是FTI可以独立于其对前层蛋白A加工的影响而改善疾病。我们的第一个目标将是详细研究这个问题，通过分析额外的基因靶向小鼠模型，并通过更好地定义FTIs在体内对前层蛋白A代谢的影响。我们的第二个目的是进一步检查我们的HGPS小鼠中的意外发现，即通过减少野生型核纤层蛋白A的合成（通过用“仅核纤层蛋白C”等位基因替换LmnaHG/+小鼠中的野生型Lmna等位基因），可以显著减少与LmnaHG等位基因相关的核形状异常和疾病表型。对这一发现的一种解释是，野生型前核纤层蛋白A（或核纤层蛋白A）导致早衰症，而核纤层蛋白C则不会。在接下来的几年中，我们将通过研究LmnaHG等位基因在“仅核纤层蛋白C”等位基因和“仅核纤层蛋白A”等位基因存在下对疾病表型和核力学的影响来相当详细地研究这一概念。我们的第三个目标是探索非法尼基化的前核纤层蛋白A的生理影响。用FTI治疗早衰症将导致非法尼基化的前核纤层蛋白A（来自野生型Lmna等位基因）的积累。这种异常蛋白质的性质以及它是否表现出自身的毒性尚不清楚。我们将通过分析nonfarnesylated前核纤层蛋白A-只有小鼠和检查核纤层蛋白对细胞和组织生理学的影响来解决这个问题。公共卫生相关性拟议的研究将确定细胞核结构蛋白的突变如何导致过早衰老或早衰症。将建立新的小鼠模型来研究疾病的发展并测试新的治疗方法。