Laboratory of Genetics and Genomics, National Institute on Aging (NIA) Intramural Research Program (IRP), National Institutes of Health (NIH), Baltimore, MD 21224, USA.
Aging (Albany NY). 2023 Apr 19;15(8):2824-2851. doi: 10.18632/aging.204666.
Senescence is a state of enduring growth arrest triggered by sublethal cell damage. Given that senescent cells actively secrete proinflammatory and matrix-remodeling proteins, their accumulation in tissues of older persons has been linked to many diseases of aging. Despite intense interest in identifying robust markers of senescence, the highly heterogeneous and dynamic nature of the senescent phenotype has made this task difficult. Here, we set out to comprehensively analyze the senescent transcriptome of human diploid fibroblasts at the individual-cell scale by performing single-cell RNA-sequencing analysis through two approaches. First, we characterized the different cell states in cultures undergoing senescence triggered by different stresses, and found distinct cell subpopulations that expressed mRNAs encoding proteins with roles in growth arrest, survival, and the secretory phenotype. Second, we characterized the dynamic changes in the transcriptomes of cells as they developed etoposide-induced senescence; by tracking cell transitions across this process, we found two different senescence programs that developed divergently, one in which cells expressed traditional senescence markers such as () mRNA, and another in which cells expressed long noncoding RNAs and splicing was dysregulated. Finally, we obtained evidence that the proliferation status at the time of senescence initiation affected the path of senescence, as determined based on the expressed RNAs. We propose that a deeper understanding of the transcriptomes during the progression of different senescent cell phenotypes will help develop more effective interventions directed at this detrimental cell population.
衰老（senescence）是一种由亚致死性细胞损伤引发的持续生长停滞状态。鉴于衰老细胞会主动分泌促炎和基质重塑蛋白，这些蛋白在老年人组织中的积累与许多衰老相关疾病有关。尽管人们强烈关注于鉴定衰老的稳健标志物，但衰老表型的高度异质性和动态性质使得这项任务变得困难。在这里，我们通过两种方法进行单细胞 RNA 测序分析，旨在全面分析人二倍体成纤维细胞的衰老转录组。首先，我们对不同应激诱导的衰老培养物中的不同细胞状态进行了特征描述，发现了表达与生长抑制、存活和分泌表型相关的蛋白质编码 mRNA 的不同细胞亚群。其次，我们描述了细胞在形成依托泊苷诱导的衰老过程中转录组的动态变化；通过跟踪该过程中的细胞转变，我们发现了两种不同的衰老程序，一种是细胞表达传统的衰老标志物，如 () mRNA，另一种是细胞表达长非编码 RNA 且剪接失调。最后，我们获得的证据表明，衰老起始时的增殖状态会影响衰老的路径，这是基于表达的 RNA 来确定的。我们提出，更深入地了解不同衰老细胞表型进展过程中的转录组，将有助于开发针对这种有害细胞群体的更有效的干预措施。
