Replicative Senescence in Human Fibroblasts Is Delayed by Hydrogen Sulfide in a NAMPT/SIRT1 Dependent Manner

Recent evidence suggests that hydrogen sulfide (H2S) has cytoprotective and anti-aging effects. However, the mechanisms for such properties are not fully understood. Here, we show that the expression of the main H2S producing enzyme, CBS, and production of H2S are coordinately diminished in replicative senescent adult human dermal fibroblasts. The reduced production of H2S falls within the same time-frame that the hallmarks of replicative senescence appear including accumulation of SA–β-Gal, enhanced expression of p16, p21, and RRM2B while the expression of RRM2, hTERT, SIRT1, NAMPT, and NAD/NADH ratio all fall. Exogenous H2S increases the expression of hTERT, NAMPT, SIRT1 and NAD/NADH ratio in treated cells. Moreover, H2S safeguards the expression of hTERT in a NAMPT and SIRT1 dependent manner and delays the onset of replicative senescence as evidenced by reduced accumulation of age associated SA–β-Gal and cessation of proliferation. Postponement of loss of cell proliferative capacity without risk of mutagenesis shows implications for use of H2S in delaying the adverse effects of senescence in organisms.

近年研究证据显示，硫化氢（hydrogen sulfide, H2S）具备细胞保护与抗衰老的生物学功效。然而，其介导上述效应的具体分子机制尚未完全阐明。本研究发现，在复制性衰老（replicative senescence）的成人皮肤成纤维细胞（adult human dermal fibroblasts）中，H2S的主要合成酶胱硫醚β合酶（cystathionine β-synthase, CBS）的表达水平与H2S生成量均呈协同性下降。H2S生成量的下降时间窗与复制性衰老标志性特征的出现时间窗完全重合：此类特征包括衰老相关β半乳糖苷酶（senescence-associated β-galactosidase, SA-β-Gal）的积累、p16、p21与RRM2B表达水平的上调，而RRM2、端粒酶逆转录酶（human telomerase reverse transcriptase, hTERT）、沉默信息调节因子1（Sirtuin 1, SIRT1）、烟酰胺磷酸核糖转移酶（nicotinamide phosphoribosyltransferase, NAMPT）的表达水平以及NAD/NADH比值均出现降低。外源性硫化氢可上调处理细胞中hTERT、NAMPT与SIRT1的表达水平，并提升NAD/NADH比值。此外，硫化氢可通过NAMPT与SIRT1依赖的途径维持hTERT的表达，同时延缓复制性衰老的发生——这一效应可通过衰老相关SA-β-Gal积累减少与细胞增殖停滞得到验证。在无诱变风险的前提下延缓细胞增殖能力的丧失，这一发现为利用硫化氢延缓生物体衰老相关的不良影响提供了潜在的应用价值。