(WHS-K3.03) AMPK and Rac1 Activity Regulation Promotes Wound Healing via Induction of Actin Cable Formation
Thursday, May 16, 2024
9:15 AM – 10:15 AM East Coast USA Time
Background: Unlike adults, early developing fetuses can completely regenerate tissue, and replicating this could lead to developing treatments to reduce scarring. Mice epidermal structures, including texture patterns, are regenerated until embryonic day (E) 13, leaving visible scars thereafter. Although the formation of actin cables at the wound margin and epidermal cell migration are known to be involved in this transition, the detailed mechanism remains unclear. We focused on AMP-activated protein kinase (AMPK) and Rac1, factors involved in regulating cell migration and actin dynamics, and investigated their effects on skin regeneration through regulation of AMPK and Rac1 activity using a unique mouse fetal wound healing model.
Methods: (1) Regulation of Rac1 activity: The mouse epidermal cell line PAM212 was treated with the Rac1 inhibitor NSC23766 and the effect on migration ability was evaluated by scratch assay. We generated genetically engineered mice (K14-CreERT2;Rac1flox/flox) that can suppress epidermis-specific Rac1 cell migration and observed the wound healing process and actin dynamics in fetuses and adults. (2) Regulation of AMPK activity: Keratinocytes were established from fetal mouse tissues and treated with AMPK activator salicylate, and the effect on migration ability was evaluated by scratch assay. Embryos of ICR mice E13, E14, and E15 were wounded and salicylate was administered into the amniotic fluid and collected at multiple time points. Wound morphology was analyzed by 3D reconstruction of the wound images, and the presence of actin cable formation and the behavior of related molecules were observed.
Results: Keratinocyte migration was suppressed by NSC23766 and salicylate administration. In a mouse model in which epidermis-specific Rac1 can be knocked out conditionally, actin cable-like stress fiber formation occurred in the epidermis of wounds after E14. In salicylate-treated fetal wounds, significant improvement in wound area and depth was observed at E14 and E15, and AMPK was activated to induce actin cable formation during wound healing, a process that normally disappears.
Conclusion: The actin cables are involved in the complete regeneration of skin, and the induction of actin cable formation through AMPK activation and Rac1 regulation was observed to induce skin regeneration or promote healing. This finding suggests that regulation of AMPK and Rac1 may be a candidate therapeutic approach to improve the wound healing process.