Proteomic and secretomic comparison of young and aged dermal fibroblasts highlights cytoskeleton as a key component during aging

Crucial for skin homeostasis, synthesis and degradation of extracellular matrix components are orchestrated by dermal fibroblasts. During aging, alterations of component expression, such as collagens and enzymes, lead to reduction of the mechanical cutaneous tension and defects of skin wound healing. The aim of this study was to better understand the molecular alterations underwent by fibroblasts during aging by comparing secretomic and proteomic signatures of fibroblasts from young (<35years) and aged (>55years) skin donors, in quiescence or TGF-stimulated conditions, using HLPC/MS. The comparison of the secretome from young and aged fibroblasts revealed that 16 proteins in resting condition, and 11 proteins after a 24h-lasting TGF-β1-treatment, were expressed in significant different ways between the two cell groups (fold change>2, p-value <0.05), with a 77% decrease in the number of secreted proteins in aged cells. Proteome comparison between young and aged fibroblasts identified a significant change of 63 proteins in resting condition, and 73 proteins in TGF-β1-stimulated condition, with a 67% increase in the number of proteins in aged fibroblasts. The majority of the differentially-expressed molecules belongs to the cytoskeleton-associated proteins and aging was characterized by an increase in Coronin 1C (CORO1C), and Filamin B (FLNB) expression in fibroblasts together with a decrease in Cofilin (CFL1), and Actin alpha cardiac muscle 1 (ACTC1) detection in aged cells, these proteins being involved in actin-filament polymerization and sharing co-activity in cell motility. Our present data reinforce knowledge about an age-related alteration in the synthesis of major proteins linked to the migratory and contractile functions of dermal human fibroblasts.