Actin dynamics regulate immediate PAR-2-dependent responses to acute epidermal permeability barrier abrogation

The skin's epidermal barrier is crucial for maintaining hydration and defense. Lamellar body (LB) secretion and stratum granulosum (SG) cell differentiation are key to this process. Protease-activated receptor-2 (PAR-2) and caveolin-1 (cav-1) are known to signal these processes. However, the early cytoskeletal changes following barrier disruption remain unclear. Prior research has shown that G-actin accumulates in SG cells under normal conditions. Yet, the dynamic response of actin to acute barrier abrogation is not well understood. This gap motivated a study to examine keratinocyte cytoskeletal remodeling in mouse models. The role of PAR-2 and cav-1 in this process is still under investigation. No prior work had resolved how actin dynamics influence LB secretion. This uncertainty drove the need for a focused investigation.

This study aimed to investigate how actin dynamics regulate early responses to acute epidermal permeability barrier disruption. Specifically, it sought to determine the role of PAR-2 and cav-1 in cytoskeletal remodeling of keratinocytes. The research focused on the apical movement of F-actin and the retreat of G-actin in SG cells following barrier abrogation. It also aimed to clarify the interaction between cytoskeletal changes and plasma membrane conformational shifts. The study tested whether PAR-2 agonists influence actin stress fiber formation. Additionally, it examined how cav-1 deficiency affects E-cadherin-mediated adhesion. The goal was to understand how these factors control LB secretion and keratinocyte adhesion. This work addresses a specific knowledge gap in barrier function regulation.

The study used three mouse models: hairless mice, PAR-2 knockout (-/-), and cav-1 knockout (-/-). Researchers examined cytoskeletal remodeling in keratinocytes following acute barrier abrogation. They analyzed the distribution of G-actin and F-actin in SG cells under basal and post-abrogation conditions. Cytoskeletal kinases were assessed for activation patterns. PAR-2 agonists were applied to test their effect on actin dynamics. Cytochalasin-D was used to inhibit actin polymerization. Plasma membrane conformational changes were observed in response to PAR-2 activation. The interaction between actin stress fibers and cav-1 was studied in wildtype and knockout cells. E-cadherin-mediated adhesion was evaluated in cav-1 -/- mice.

Barrier abrogation triggered apical movement of F-actin and retreat of G-actin in SG cells. This shift was accompanied by activation of upstream cytoskeletal kinases. PAR-2 agonists enhanced this actin remodeling effect. Cytochalasin-D and PAR-2 knockout mice inhibited the process. Plasma membrane conformational changes were linked to PAR-2-dependent cytoskeletal rearrangements. In cav-1 -/- cells, actin stress fiber formation increased both before and after PAR-2 agonist treatment. Cav-1 deficiency also reduced E-cadherin-mediated adhesion. These findings suggest that PAR-2 regulates early LB secretion through cytoskeletal dynamics.

The authors propose that PAR-2 drives cytoskeletal and plasma membrane changes following barrier disruption. These changes regulate LB secretion, stress fiber formation, and keratinocyte adhesion. The study shows that PAR-2 agonists enhance actin remodeling, while cytochalasin-D and PAR-2 knockout inhibit it. Cav-1 deficiency increases actin stress fibers but reduces cell adhesion. The findings suggest that cytoskeletal dynamics are essential for early barrier repair. The role of cav-1 in E-cadherin adhesion is highlighted. These results align with the observed effects of PAR-2 activation. The conclusions reflect the direct claims made in the abstract.