New Therapeutic Approaches for Hutchinson-Gilford Progeria Syndrome

描述(由申请人提供)： 这项建议的目的是使用小鼠模型来测试Hutchinson-Gilford早衰症(HGPS)的潜在治疗策略。患有HGPS的儿童会发展出一系列类似衰老的疾病表型，包括过早的动脉粥样硬化。大多数HGPS病例是由LMNA(前层蛋白A和层蛋白C的基因)的从头突变引起的。这种突变导致突变的前层蛋白A(通常被称为孕激素)的合成，而内切酶ZMPSTE24无法将其加工成成熟层粘蛋白A。孕激素在其羧基末端发生法尼化。由于这种法尼基脂质锚的存在，孕激素聚集在核缘(沿着核内膜)，导致细胞核严重畸形。缺乏ZMPSTE24的细胞也会在核缘积聚法尼化的前层蛋白A，并有严重畸形的细胞核。我们假设，用法尼基转移酶抑制剂(FTI)阻断蛋白质的法尼化会使孕激素(或在ZMPSTE24缺乏的情况下是前层蛋白A)错位地远离核膜，并减少畸形核的频率。事实上，HGPS突变的人和小鼠细胞以及缺乏ZMPSTE24的人和小鼠细胞都是如此。这些发现非常令人鼓舞，因为它们提出了一种可能的HGPS治疗策略。在过去的一年里，我们培育了一只产生层粘连蛋白C但不产生层粘连蛋白A或前粘连蛋白A的小鼠。值得注意的是，只有层粘连蛋白C的小鼠是完全健康的。这一发现表明，层蛋白A是可有可无的，并暗示有可能通过减少前层蛋白A/层蛋白A的合成来治疗包括HGPS在内的任何“层蛋白A”疾病。小鼠的遗传实验有力地支持了这一概念。这项建议的一个关键目标是检验这样一种假设，即通过FTI将前层素A或孕激素错误地定位于远离核膜的位置，可以防止小鼠模型中的早衰症表型。初步研究强烈表明，FTI确实可能是有效的。FTI治疗HGPS会导致非法尼化孕激素的积累。第二个目标是创造一种新的以基因为靶标的小鼠模型，表达非法尼化版本的孕激素。通过检查这些新的基因靶标小鼠，我们应该能够确定非法尼化孕激素的合成是否与任何不利的疾病表型有关。该提案的第三个目标是确定使用反义寡核苷酸减少前层素A的合成是否可以改善小鼠模型中的早衰症表型。初步研究还表明，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可喜的进展。

DESCRIPTION (provided by applicant): 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.