New Therapeutic Approaches for Hutchinson-Gilford Progeria Syndrome

该提案的目的是使用小鼠模型来测试潜在的治疗策略， Hutchinson-Gilford早衰综合征（HGPS）。 患有HGPS的儿童会出现许多衰老样疾病表型，包括早产儿， 动脉粥样硬化大多数HGPS病例是由LMNA（HGPS基因）的从头点突变引起的 前核纤层蛋白A和核纤层蛋白C）。这种突变导致突变体前核纤层蛋白A（通常称为 早老蛋白）不能被内切蛋白酶ZMPSTE 24加工成成熟核纤层蛋白A。早老素是 在其羧基末端法尼基化。由于存在这种法呢基脂质锚，早老蛋白 聚集在核边缘（沿着内核膜）并导致严重畸形的核。 缺乏ZMPSTE 24的细胞也在核边缘积累法尼基化的核纤层蛋白前体A，并且具有明显的细胞毒性。 畸形的细胞核 我们假设用法尼基转移酶抑制剂（FTI）阻断蛋白质法尼基化， 使早老蛋白（或在ZMPSTE 24缺陷的情况下的前层蛋白A）远离核膜错误定位 减少畸形细胞核的发生率事实上，人类和小鼠的细胞都是如此， 与HGPS突变和人类和小鼠细胞缺乏ZMPSTE 24。这些发现非常 令人鼓舞，因为他们提出了一种可能的治疗HGPS的策略。 在过去的一年中，我们产生了一种产生核纤层蛋白C但不产生核纤层蛋白A或核纤层蛋白前体A的小鼠。 值得注意的是，“仅核纤层蛋白C”小鼠是完全健康的。这一发现表明，核纤层蛋白A是一种蛋白质， 并暗示通过减少合成来治疗任何“核纤层蛋白A”疾病（包括HGPS）是可能的 核纤层蛋白A前体/核纤层蛋白A。在老鼠身上进行的遗传实验有力地支持了这一概念。 这项提议的一个关键目标是检验一个假设，即错误定位前核层蛋白A或早老蛋白， 具有FTI的核被膜将预防小鼠模型中的早衰样疾病表型。 初步研究强烈表明，FTI可能确实有效。HGPS的FTI治疗 导致非法尼基化的早老蛋白的积累。第二个目标是产生一个新的基因靶向 表达非法尼基化形式的早老蛋白的小鼠模型。通过检测这些新的基因靶向 小鼠，我们应该能够确定非法尼基化的早老蛋白的合成是否与任何 不良疾病表型。该提案的第三个目标是确定减少前层蛋白A的合成 与反义寡核苷酸一起使用可以改善小鼠模型中的早衰症表型。 初步研究也表明，这一战略是可行的。这些研究很有可能 确定HGPS的治疗方法，这对受这种疾病影响的人来说是一个受欢迎的发展。

The objective of this proposal is to use mouse models to test potential therapeutic strategies for Hutchinson-Gilford progeria syndrome (HGPS). Children with HGPS develop a host of aging-like disease phenotypes, including premature atherosclerosis. Most cases of HGPS are caused by a de novo point mutation in LMNA (the gene for prelamin A and lamin C). This mutation leads to the synthesis of a mutant prelamin A (commonly called progerin) that cannot be processed to mature lamin A by the endoprotease ZMPSTE24. Progerin is farnesylated at its carboxyl terminus. Because of the presence of this farnesyl lipid anchor, progerin accumulates at the nuclear rim (along the inner nuclear membrane) and causes grossly misshapen nuclei. Cells lacking ZMPSTE24 also accumulate farnesylated prelamin A at the nuclear rim and have grossly misshapen nuclei. We hypothesized that blocking protein farnesylation with a farnesyltransferase inhibitor (FTI) would mislocalize progerin (or prelamin A in the case of ZMPSTE24 deficiency) away from the nuclear envelope and reduce the frequency of misshapen nuclei. Indeed, this was the case, both for human and mouse cells with an HGPS mutation and for human and mouse cells lacking ZMPSTE24. These findings were extremely encouraging because they suggested a possible treatment strategy for HGPS. During the past year, we generated a mouse that produces lamin C but no lamin A or prelamin A. Remarkably, "lamin C-only" mice are entirely healthy. This finding suggested that lamin A is dispensable and implied that it may be possible to treat any "lamin A" disease, including HGPS, by reducing the synthesis of prelamin A/lamin A. Genetic experiments in mice have strongly supported this concept. A key goal of this proposal is to test the hypothesis that mislocalizing prelamin A or progerin away from the nuclear envelope with an FTI would prevent the progeria-like disease phenotypes in mouse models. Preliminary studies have strongly suggested that FTIs might indeed be efficacious. FTI treatment of HGPS results in the accumulation of a nonfarnesylated progerin. A second goal is to generate a new gene-targeted mouse model that expresses a nonfarnesylated version of progerin. By examining these new gene-targeted mice, we should be able to determine if the synthesis of nonfarnesylated progerin is associated with any adverse disease phenotypes. A third goal of the proposal is to determine if decreasing prelamin A synthesis with an antisense oligonucleotide could ameliorate progeria disease phenotypes in mouse models. Preliminary studies also suggest that this strategy is feasible. These studies stand a significant chance of identifying treatments for HGPS, which would be a welcome development for those affected by this disease.