Modification of Collagen by 3-Deoxyglucosone Alters Wound Healing through Differential Regulation of p38 MAP Kinase

Danielle T Loughlin,Carol M Artlett,Nai Sum Wong

doi:10.1371/journal.pone.0018676

Abstract

BackgroundWound healing is a highly dynamic process that requires signaling from the extracellular matrix to the fibroblasts for migration and proliferation, and closure of the wound. This rate of wound closure is impaired in diabetes, which may be due to the increased levels of the precursor for advanced glycation end products, 3-deoxyglucosone (3DG). Previous studies suggest a differential role for p38 mitogen-activated kinase (MAPK) during wound healing; whereby, p38 MAPK acts as a growth kinase during normal wound healing, but acts as a stress kinase during diabetic wound repair. Therefore, we investigated the signaling cross-talk by which p38 MAPK mediates wound healing in fibroblasts cultured on native collagen and 3DG-collagen.Methodology/Principal FindingsUsing human dermal fibroblasts cultured on 3DG-collagen as a model of diabetic wounds, we demonstrated that p38 MAPK can promote either cell growth or cell death, and this was dependent on the activation of AKT and ERK1/2. Wound closure on native collagen was dependent on p38 MAPK phosphorylation of AKT and ERK1/2. Furthermore, proliferation and collagen production in fibroblasts cultured on native collagen was dependent on p38 MAPK regulation of AKT and ERK1/2. In contrast, 3DG-collagen decreased fibroblast migration, proliferation, and collagen expression through ERK1/2 and AKT downregulation via p38 MAPK.Conclusions/SignificanceTaken together, the present study shows that p38 MAPK is a key signaling molecule that plays a significantly opposite role during times of cellular growth and cellular stress, which may account for the differing rates of wound closure seen in diabetic populations.

Highlights

The wound healing process is a complex series of events that is characterized by several phases including inflammation, proliferation, and remodeling [1,2]
Inhibition of p38 mitogen activated protein kinase (MAPK) in fibroblasts cultured on 3DG-collagen restored the migration of fibroblasts, closing the wound by 88%62.2% in 48 h (Figure 2, p,0.001). These results suggest that p38 MAPK may be acting as a stress kinase in the presence of 3DG-collagen resulting in decreased migration, while p38 MAPK may act as a growth response kinase in fibroblasts cultured on native collagen allowing for fibroblast migration and closure of the wound
We found that the rate of proliferation in fibroblasts cultured on native collagen was dependent on AKT but not ERK1/2 as only inhibition of AKT showed similar levels of proliferation to that seen in fibroblasts pretreated with the p38 MAPK inhibitor (Figure 4, p,0.01)

Summary

Introduction

The wound healing process is a complex series of events that is characterized by several phases including inflammation, proliferation, and remodeling [1,2]. Among these are the growth activated protein kinases including extracellular signal-regulated protein kinase (ERK), the protein kinase B (PKB/AKT), and the stress-activated protein kinase p38 MAPK Both ERK and AKT play an important role in signaling during cell proliferation, while p38 MAPK has been classically associated with apoptosis and cellular stress [12,13,14,15,16,17,18]. We have shown that inhibition of p38 MAPK resulted in caspase-3 activation in dermal fibroblast cultured on native collagen, while it inhibited 3DG-collagen-induced caspase-3 activity [11] This dichotomy suggests that p38 MAPK can be activated to signal as either a growth kinase or a stress kinase which is dependent upon extracellular stimuli.

Results

Discussion

Findings

Materials and Methods