Biomolecular Fingerprints of Sirtuin Activity in Senescent Fibroblasts Identified via Synchrotron-Based FTIR

Sirtuins are NAD⁺-dependent enzymes widely implicated in organismal ageing. In particular, nuclear-located sirtuins are histone deacetylases and/or monoADPrybosiltransferases that exert key roles in maintaining genomic stability. Although sirtuins have been reported to play an inhibitory role in cellular senescence, their specific targets and underlying mechanisms remain poorly understood. In this study, we use single-cell Synchrotron radiation-based Fourier-transform infrared spectroscopy (FTIR) to identify changes in biomolecular composition associated with cellular senescence induced by oxidative stress and replicative passaging in human primary fibroblasts. We also use the sirtuin activator resveratrol to determine which of these changes may be related to sirtuin activity. Resveratrol induced changes related to nuclear architecture, such as DNA conformation and nucleic acid-protein abundance ratios. Individual targeting of nuclear sirtuins was used to validate impaired DNA/protein ratios experimentally and provided a specific structural footprint associated with sirtuins in the context of cellular senescence. Altogether, this study reveals for the first time a sirtuin-dependent structural and biomolecular signature of senescence through single-cell FTIR, offering new insights into the cellular events underlying cellular senescence.