Candelario Jose, Chen Leng-Ying, Marjoram Paul, Reddy Sita, Comai Lucio
Department of Molecular Microbiology and Immunology, University of Southern California, Los Angeles, CA 90033, USA.
Aging (Albany NY). 2012 Aug;4(8):567-77. doi: 10.18632/aging.100483.
Small increases in the expression of wild-type prelamin A are sufficient to recapitulate the reduced cell proliferation and altered nuclear membrane morphology observed in cells expressing progerin, the mutant lamin A associated with progeria. We hypothesized that the manifestation of these phenotypes in cells expressing elevated levels of wild-type prelamin A or progerin is caused by the same molecular effectors, which play a central role in the onset of the progeroid phenotype. To experimentally test this hypothesis, we compared the transcriptomes of isogenic diploid fibroblasts expressing progerin or elevated levels of wild-type prelamin A with that of wild-type fibroblasts. We subsequently used the reversion towards normal of two phenotypes, reduced cell growth and dismorphic nuclei, by treatment with farnesyltransferase inhibitor (FTI) or overexpression of ZMPSTE24, as a filtering strategy to identify genes linked to the onset of these two phenotypes. Through this analysis we identified the gene encoding for the transcription factor FOXQ1, as a gene whose expression is induced in both cells expressing progerin and elevated levels of wild-type prelamin A, and subsequently reduced in both cell types upon conditions that ameliorate the phenotypes. We overexpressed FOXQ1 in normal fibroblasts and demonstrated that increased levels of this factor lead to the development of both features that were used in the filtering strategy. These findings suggest a potential link between this transcription factor and cell dysfunction induced by altered prelamin A metabolism.
野生型前层粘连蛋白A表达的小幅增加足以重现早老蛋白（与早衰相关的突变型层粘连蛋白A）表达细胞中观察到的细胞增殖减少和核膜形态改变。我们假设，在野生型前层粘连蛋白A或早老蛋白表达水平升高的细胞中，这些表型的表现是由相同的分子效应器引起的，这些效应器在早衰样表型的发生中起核心作用。为了通过实验验证这一假设，我们将表达早老蛋白或野生型前层粘连蛋白A水平升高的同基因二倍体成纤维细胞的转录组与野生型成纤维细胞的转录组进行了比较。随后，我们采用法尼基转移酶抑制剂（FTI）处理或ZMPSTE24过表达使细胞生长减少和核畸形这两种表型恢复正常，作为一种筛选策略来鉴定与这两种表型发生相关的基因。通过该分析，我们鉴定出编码转录因子FOXQ1的基因，该基因在表达早老蛋白和野生型前层粘连蛋白A水平升高的细胞中均被诱导表达，随后在改善表型的条件下，这两种细胞类型中的表达均降低。我们在正常成纤维细胞中过表达FOXQ1，并证明该因子水平的升高会导致筛选策略中所使用的两种特征的出现。这些发现表明该转录因子与前层粘连蛋白A代谢改变诱导的细胞功能障碍之间存在潜在联系。
