Hydrolyzed Collagen from Salmon Skin Increases the Migration and Filopodia Formation of Skin Keratinocytes by Activation of FAK/Src Pathway

Previous studies reported hydrolyzed collagen increase cell proliferation and migration involved in the wound repair process. Nevertheless, the knowledge related with wound repair mechanism of hydrolyzed collagen from salmon skin (HCSS) has not been fully elucidated. Therefore, this study aimed to elucidate the effects of HCSS on the migration of keratinocyte HaCaT cells. Additionally, its molecular mechanism through cell division control protein 42 (Cdc42), Ras-related C3 botulinum toxin substrate 1 (Rac1), and Ras homolog family member A (RhoA) via focal adhesion kinase (FAK)-steroid receptor coactivator (Src) regulation and keratinocyte stem cells (KSCs) markers were also evaluated. After 24 h of incubation, keratinocyte proliferation was detected by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) and double stranded DNA (dsDNA) assays, and by determining the total cellular protein content. Keratinocyte migration and filopodia formation were measured by wound healing assay and phalloidin‐rhodamine staining, respectively. The migratory related proteins were evaluated by western blot analysis. HCSS had a high content of hydrophobic amino acids and imino acids. HaCaT cell proliferation and migration were significantly increased in response to HCSS at the concentration of 100-1000 μg/mL. The formation of filopodia was subsequently increased in response to HCSS at concentrations of 100-1000 μg/mL. Moreover, HCSS upregulated Cdc42, Rac1, and RhoA protein expression and activated the phosphorylation of FAK and Src pathway. HCSS at the concentration of 100-1000 μg/mL could trigger stemness by increased KSC markers, including keratin 19 and β-catenin expression. This study has demonstrated that HCSS induces proliferation and migration of keratinocytes, subsequently promotes the second phase of wound healing process by FAK-Src activation and also increases the KSC properties.