Waldera Lupa Daniel M, Kalfalah Faiza, Safferling Kai, Boukamp Petra, Poschmann Gereon, Volpi Elena, Götz-Rösch Christine, Bernerd Francoise, Haag Laura, Huebenthal Ulrike, Fritsche Ellen, Boege Fritz, Grabe Niels, Tigges Julia, Stühler Kai, Krutmann Jean
Molecular Proteomics Laboratory, Heinrich-Heine-University, Düsseldorf, Germany; Biomedical Research Center (BMFZ), Heinrich-Heine-University, Düsseldorf, Germany.
Institute of Clinical Chemistry and Laboratory Diagnostics, Heinrich-Heine-University, Med. Faculty, Düsseldorf, Germany.
J Invest Dermatol. 2015 Aug;135(8):1954-1968. doi: 10.1038/jid.2015.120. Epub 2015 Mar 27.
Most molecular hallmarks of cellular senescence have been identified in studies of cells aged in vitro by driving them into replicative or stress-induced senescence. Comparatively, less is known about the characteristic features of cells that have aged in vivo. Here we provide a systematic molecular analysis of normal human dermal fibroblasts (NHDFs) that were isolated from intrinsically aged human skin of young versus middle aged versus old donors. Intrinsically aged NHDFs in culture exhibited more frequently nuclear foci positive for p53 binding protein 1 and promyelocytic leukemia protein reminiscent of 'DNA segments with chromatin alterations reinforcing senescence (DNA-SCARS)'. Formation of such foci was neither accompanied by increased DNA double strand breaks, nor decreased cell viability, nor telomere shortening. However, it was associated with the development of a secretory phenotype, indicating incipient cell senescence. By quantitative analysis of the entire secretome present in conditioned cell culture supernatant, combined with a multiplex cytokine determination, we identified 998 proteins secreted by intrinsically aged NHDFs in culture. Seventy of these proteins exhibited an age-dependent secretion pattern and were accordingly denoted 'skin aging-associated secreted proteins (SAASP)'. Systematic comparison of SAASP with the classical senescence-associated secretory phenotype (SASP) revealed that matrix degradation as well as proinflammatory processes are common aspects of both conditions. However, secretion of 27 proteins involved in the biological processes of 'metabolism' and 'adherens junction interactions' was unique for NHDFs isolated from intrinsically aged skin. In conclusion, fibroblasts isolated from intrinsically aged skin exhibit some, but not all, molecular hallmarks of cellular senescence. Most importantly, they secrete a unique pattern of proteins that is distinct from the canonical SASP and might reflect specific processes of skin aging.
细胞衰老的大多数分子特征是在体外培养的细胞研究中发现的，通过促使它们进入复制性衰老或应激诱导的衰老。相比之下，对于体内衰老细胞的特征了解较少。在这里，我们对从年轻、中年和老年供体的自然衰老人类皮肤中分离出的正常人皮肤成纤维细胞（NHDFs）进行了系统的分子分析。培养中的自然衰老NHDFs更频繁地出现核灶，这些核灶对p53结合蛋白1和早幼粒细胞白血病蛋白呈阳性，让人联想到“具有染色质改变的DNA片段强化衰老（DNA-SCARS）”。这种核灶的形成既不伴随着DNA双链断裂的增加，也不伴随着细胞活力的降低，也不伴随着端粒缩短。然而，它与分泌表型的发展有关，表明细胞开始衰老。通过对条件细胞培养上清液中存在的整个分泌组进行定量分析，并结合多重细胞因子测定，我们鉴定出培养中的自然衰老NHDFs分泌的998种蛋白质。其中70种蛋白质表现出年龄依赖性分泌模式，因此被称为“皮肤衰老相关分泌蛋白（SAASP）”。SAASP与经典衰老相关分泌表型（SASP）的系统比较表明，基质降解以及促炎过程是这两种情况的共同方面。然而，参与“代谢”和“黏附连接相互作用”生物过程的27种蛋白质的分泌是从自然衰老皮肤中分离出的NHDFs所特有的。总之，从自然衰老皮肤中分离出的成纤维细胞表现出细胞衰老的一些但不是全部分子特征。最重要的是，它们分泌一种独特的蛋白质模式，与经典的SASP不同，可能反映了皮肤衰老的特定过程。
