Protease Activated Receptor-2 Mediates Activated Protein C–Induced Cutaneous Wound Healing via Inhibition of p38

Abstract

Activated protein C (APC) is a natural anticoagulant that exerts anti-inflammatory and cytoprotective properties mediated through the protease activated receptor (PAR)-1. APC can also proteolytically cleave PAR-2, although subsequent function is unknown. On the basis of recent evidence that APC promotes wound healing, the aim of this study was to determine whether APC acts through PARs to heal murine excisional wounds or to regulate human cultured keratinocyte function and to determine the signaling mechanisms. Topical administration of APC accelerated wound healing in wild-type mice and, unexpectedly, in PAR-1 knockout mice. PAR-2 knockout mice healed significantly slower than wildtype mice, and healing was not altered by adding APC, indicating that APC acts through PAR-2 to heal wounds. In cultured human primary keratinocytes, APC enhanced PAR-2, stimulated proliferation, activated phosphatidylinositol 3-kinase/Src/Akt, and inhibited phosphorylated (P)-p38. Inhibiting PAR-1 or PAR-2, by small-interfering RNA or blocking antibody, reversed APC-induced keratinocyte proliferation and Akt activation. Blocking PAR-2, but not PAR-1, reversed the inhibition of P-p38 by APC. Furthermore, inhibition of P-p38 accelerated wound healing in wild-type mice. In summary, although APC acts through both PAR-1 and PAR-2 to activate Akt and to increase keratinocyte proliferation, APC-induced murine wound healing depends on PAR-2 activity and inhibition of P-p38.

Activated Protein C Inhibits Proliferation and Tumor Necrosis Factor α-Stimulated Activation of p38, c-Jun NH2-Terminal Kinase (JNK) and Akt in Rheumatoid Synovial Fibroblasts

“…Nonetheless, numerous studies have shown that APC exerts antiinflammatory and cyto-protective properties in various organs and that these effects are often mediated by endothelial protein C receptor (EPCR) and proteinase-activated receptors (PARs) (14)(15)(16)(17).…”

Hepatocyte Growth Factor Activator Inhibitor Type 1 Maintains the Assembly of Keratin into Desmosomes in Keratinocytes by Regulating Protease-Activated Receptor 2–Dependent p38 Signaling

“…35,52 In contrast, activated protein Cemediated activation of PAR-2 inhibited the phosphorylation of p38 in human primary keratinocytes. 53 Therefore, p38 signaling, modulated by PAR-2 activation, may be highly dependent on the cellular context or type.…”

Differential Effects of Activated Protein C on Synovial Fibroblasts in Response to Hypoxia and Normoxia

“…A previous study showed that under hypoxic conditions, p38 mitogen-activated protein kinase (p38MPAK) is essential for fibroblast proliferation and acts as a modulator of pro-inflammatory responses in rheumatological conditions (Mortimer et al 2007). Indeed, if protease-activated receptors (PARs) are activated, they signal via p38 to induce immune responses (Julovi et al 2011;Riewald & Ruf 2005). Thus, we expected that activation of p38 by APC under hypoxic conditions would be involved in the proliferation and anti-inflammatory response of RAFb.…”

“…Cell proliferation assays were performed as described previously (Julovi et al 2011). Cells (2 × 10 3 cells/well) were seeded into 96-well microplates to a final volume of 200 μL and incubated for 4 h to allow cells to attach.…”

“…The anti-inflammatory activity of APC is associated with decreased leucocyte recruitment and proinflammatory mediators (Esmon 2012;Minhas et al 2010). APC reduces inflammation by regulating p38 activity by activating protease-activated receptor-2 (PAR-2) (Julovi et al 2011). APC is elevated in RA synovial joints and fluids and co-localizes with matrix metalloproteinase (MMP)-2 in the lining layer (Buisson-Legendre et al 2004;.…”