The p38-MAPK/SAPK Pathway is Required for Human Keratinocyte Migration on Dermal Collagen

Abstract

Human keratinocyte motility plays an important role in the re-epithelialization of human skin wounds. The wound bed over which human keratinocytes migrate is rich in extracellular matrices, such as fibrin, fibronectin, and collagen, and serum factors, such as platelet-derived growth factor and transforming growth factor beta 1. Extracellular matrices and the serum factors bind to cell surface receptors and initiate a cascade of intracellular signaling events that regulate cell migration. In this study, we identified an intracellular signaling pathway that mediates collagen- driven motility of human keratinocytes. Pharmaco logic inhibition of the activation of p38-alpha and p38-beta mitogen-activated protein kinase activation potently blocked collagen-driven human keratinocyte migration. Transfection of the same keratinocytes with the kinase-negative mutants of p38-alpha or p38-beta mitogen-activated protein kinase markedly inhibited keratinocyte migration on collagen. Attachment of keratinocytes to collagen activated p38 mitogen- activated protein kinase, as well as p44/p42 ERKs. Interestingly, activation of the p38 mitogen-activated protein kinase cascade by overexpressing the constitutively active MKK3 and MKK6, MKK3b(E) and MKK6b(E), could neither initiate migration in the absence of collagen nor enhance collagen-driven migration. This study provides evidence that the p38-MAPK/SAPK pathway is necessary, but insufficient, for mediating human keratinocyte migration on collagen.

Inhibition of p38MAP kinase suppresses fibrotic reaction of retinal pigment epithelial cells

“…p38MAPK has also been shown to be required for TGF-b-dependent stimulation of matrix production in dermal fibroblasts, and thus inhibition of p38MAPK could potentially be effective in preventing dermal scarring. 24,26,30 It has also been shown that p38MAPK-dependent activation of Smad3 promoted deposition of extracellular matrix by myofibroblasts both in vitro and in vivo. 24,26,30,31 These reports together with our findings lead us to hypothesize that inhibition of p38MAPK may be beneficial in preventing/treating PVR.…”

“…24,26,30 It has also been shown that p38MAPK-dependent activation of Smad3 promoted deposition of extracellular matrix by myofibroblasts both in vitro and in vivo. 24,26,30,31 These reports together with our findings lead us to hypothesize that inhibition of p38MAPK may be beneficial in preventing/treating PVR. Although PVR is caused by the activation of many cell types, that is, retinal glial components, vascular cells, and so on, activation and fibroblastic transformation of RPE cells is a critical feature in the development of this disease.…”

“…This result is consistent with previous studies demonstrating an involvement of p38MAPK in promotion of cell migration of epidermal keratinocytes, mammary epithelial cell line or others. [19][20][21][22][23][24][25] In other studies, we have also shown that loss of Smad3, the key mediator of TGF-b signaling from cell surface receptors, results in loss of chemotactic responses to TGF-b in keratinocytes, Figure 10 Expression of aSMA and collagen type VI in experimental PVR mouse eyes treated with either control LacZ-Ad or DN p38MAPK-Ad. At day 2 pigment epithelial cells were labeled with anti-aSMA antibody (a, white arrows) in LacZ-Ad control specimens, but not in DN p38MAPK-Ad specimens (d, yellow arrows).…”

“…20 p38MAPK has been implicated in TGF-bmediated fibroblastic transdifferentiation and cell migration in cultured tumor-derived and non-tumorderived mammary epithelial cells. [21][22][23][24][25][26][27] We and others have also recently reported that the TGF-b2/ p38MAPK cascade, which is activated in mouse corneal epithelium upon epithelial debridement, is needed for epithelial cell migration and cessation of cell proliferation. 28,29 In mesenchymal cells, p38MAPK is involved in expression of ECM molecules, that is, collagen or fibronectin and cell proliferation.…”

p38 Mitogen-activated Protein Kinase Regulation of Endothelial Cell Migration Depends on Urokinase Plasminogen Activator Expression

“…The effects of p38 MAPKs are mediated by various p38 MAPK substrates including MAPK-activated protein kinase 2 (MK2), MK3, and p38 MAPK-activated kinase (PRAK) (9,10). In addition to the more defined role in inflammation and cell stress responses (11), p38 MAPK has also been implicated in the cytoskeleton reorganization and the cellular migration of various cell types (12)(13)(14)(15)(16)(17)(18). The use of specific inhibitors has demonstrated the importance of p38 MAPK in endothelial cell migration stimulated by angiogenic factors such as VEGF (19).…”