Atelocollagen Increases Collagen Synthesis by Promoting Glycine Transporter 1 in Aged Mouse Skin

Aging results in decreased collagen synthesis and the disruption of extracellular matrix integrity, primarily due to increased oxidative stress. This study evaluated whether atelocollagen can restore collagen synthesis in aged skin by modulating glycine transporter 1 (GlyT1)-mediated glycine uptake, regulating oxidative stress, and influencing extracellular matrix remodeling factors in senescent human cells and the skin of older mice. Human dermal fibroblasts (HDFs) and aged mouse skin were treated with atelocollagen, with analyses of GlyT1 expression, glutathione and intracellular glycine concentrations, oxidative stress markers, nuclear factor-kappa-B (NF-κB) activity, matrix metalloproteinases (MMPs), SMAD proteins (SMADs) signaling, and collagen I/III. Treatment with GlyT1 inhibitors and glycine was tested. Atelocollagen significantly increased GlyT1 expression and intracellular glycine concentration, promoted glutathione synthesis, and reduced oxidative stress. These effects led to decreased NF-κB activity and MMP1/3/9 expression, increased SMAD2/3 phosphorylation, and upregulated type I/III collagen synthesis in senescent HDFs and aged mouse skin. All beneficial effects were blocked by GlyT1 inhibition and were generally superior to glycine alone. Histology showed increased collagen density and improved skin elasticity in atelocollagen-treated mice. In summary, atelocollagen enhances collagen synthesis and reduces oxidative stress in aged skin through GlyT1-dependent glycine transport, providing a potential strategy for skin rejuvenation.