A TAT-functionalized recombinant elastin-like polypeptide promotes dermal matrix restoration in D-galactose-induced skin aging

Restoration of dermal extracellular matrix (ECM) homeostasis represents a promising strategy for ameliorating aging-associated skin alterations; however, topical delivery of macromolecular proteins remains challenging because of the stratum corneum barrier. Here, we engineered a TAT-functionalized recombinant elastin-like polypeptide, designated RTE, by combining elastin-derived domains with a C-terminal transactivator of transcription (TAT) motif. SDS-PAGE demonstrated that the FITC-RTE formulation contained a predominant band at the expected molecular-weight region without detectable lower-molecular-weight degradation products, while extensive dialysis minimized interference from unbound FITC. Compared with the corresponding TAT-free elastin-like polypeptide (RE), RTE exhibited greater cellular association and enhanced transport and tissue distribution of RTE-associated fluorescence in ex vivo porcine and in vivo mouse skin. In vitro, RTE supported fibroblast viability and growth, promoted migration, adhesion, and cytoskeletal organization, and increased the expression of ECM-associated genes. In zebrafish, RTE protected against UVB-associated fin injury, reduced ROS-associated fluorescence, and promoted tail-fin regeneration. In a D-galactose-induced mouse model of skin aging, topical RTE improved skin hydration and barrier function and promoted the restoration of epidermal architecture, collagen deposition, and elastic-fiber organization. These improvements were accompanied by coordinated regulation of ECM synthesis and degradation, attenuation of inflammatory and senescence-associated markers, and restoration of redox homeostasis. Collectively, these findings demonstrate that RTE promotes dermal matrix restoration and ameliorates D-galactose-induced skin alterations, supporting its potential as a bioactive elastin-like polypeptide for topical skin applications.