Identification of Splicing-Related Aging Biomarkers

描述（由申请人提供）：细胞衰老是一种用于探索生物体衰老分子机制的强大体外模型。一个流行的假设是，当端粒缩短到临界点以下时，它就像一个有丝分裂时钟，决定了细胞周期的永久退出。除了端粒缩短外，某些癌基因或环境刺激（例如γ射线照射）还可能过早引发细胞衰老。还据报道，由于外显子11中的从头突变，核纤层蛋白A基因（LMNA）的前mRNA的异常剪接导致Hutchinson-Gilford早衰综合征（HGPS）患者的细胞过早衰老和加速衰老。有趣的是，HGPS中核纤层蛋白A的少量异常剪接产物（称为“早老蛋白”）在健康个体的细胞和组织中作为年龄的函数积累，表明mRNA剪接的改变不一定与突变相关，也可能受到年龄相关因素的影响。与这一思路相一致，其他一些基因，包括细胞粘附分子纤连蛋白和中间丝蛋白波形蛋白，在正常衰老细胞中选择性剪接。这一想法也在衰老相关的神经退行性疾病中得到了例证，例如阿尔茨海默病、帕金森病和tau蛋白病，所有这些疾病都涉及前mRNA剪接中的畸变。基于上述发现，我们假设在细胞衰老过程中，选择性剪接发生了广泛的变化。这些衰老相关的亚型中的一些可能是衰老细胞所特有的，并且对于细胞建立衰老状态具有重要的功能，其可以进一步发展为用于衰老的新型生物标志物。为了解决这一假设，我们将进行一系列研究，包括使用RNA-seq（Aim 1）鉴定培养的衰老细胞中的剪接变化，在体外和体内表征这些衰老相关的亚型，将其开发为衰老生物标志物（Aim 2）。

DESCRIPTION (provided by applicant): Cellular aging is a powerful in vitro model for exploring molecular mechanisms underlying organismal aging. A popular hypothesis is that, when the telomeres shorten to below a critical point, it acts as a mitotic clock dictating the permanent exit from the cell cycle. Besides telomere shortening, cellular senescence can be triggered prematurely by certain oncogenes or environmental stimuli, such as γ-irradiation. It has also been reported that an aberrant splicing of the pre-mRNA of the lamin A gene (LMNA), due to a de novo mutation in the exon 11, leads to premature cellular senescence and accelerated aging in patients with Hutchinson-Gilford progeria syndrome (HGPS). Interestingly, a small amount of the aberrant splicing product of lamin A in HGPS (named "progerin") accumulates in the cells and tissues of healthy individuals as a function of age, suggesting that alterations in mRNA splicing are not necessarily associated with mutations and may also be influenced by age-related factors. Consistent with this line of thinking, a few other genes, including a cell adhesion molecule fibronectin and an intermediate filament protein vimentin, are alternatively spliced in normal senescent cells. This idea is also exemplified in aging-related neurodegenerative diseases, such as Alzheimer's, Parkinson's diseases and tauopathies, all involving aberrations in pre-mRNAs splicing. Based on the above findings, we hypothesize that there are widespread changes in alternative splicing during cellular senescence. Some of these senescence-related isoforms may be unique to senescent cells and functionally important for cells to establishing senescence state, which can be further developed into novel biomarkers for aging. To address this hypothesis, we will conduct a series of investigations including identifying splicing changes in cultured senescent cells using RNA-seq (Aim1), characterizing these senescence-associated isoforms in vitro and in vivo to develop them into aging biomarkers (Aim2).