Precursor of Advanced Glycation End Products Mediates ER-Stress-Induced Caspase-3 Activation of Human Dermal Fibroblasts through NAD(P)H Oxidase 4

Abstract

BackgroundThe precursor for advanced glycation end products, 3-deoxyglucosone (3DG) is highly upregulated in skin explants of diabetic cutaneous wounds, and has been shown to negatively impact dermal fibroblasts, which are crucial in wound remodeling. 3DG induces apoptosis however; the mechanisms involved in the apoptotic action of 3DG in the pathogenesis of diabetic chronic wounds are poorly understood. Therefore, we sought to delineate novel mechanisms involved with the 3DG-collagen induced apoptosis.Methodology/Principal FindingsUsing human dermal fibroblasts, we demonstrated that 3DG-modified collagen induces oxidative stress and caspase-3 activation. Oxidative stress was found to be dependent on the upregulation of NAD(P)H oxidase 4 (Nox4), a reactive oxygen species (ROS) Nox homologue, triggering endoplasmic reticulum (ER) stress, as assessed by the ER stress-induced apoptosis marker Growth Arrest and DNA Damage-inducible gene 153 (GADD153). We demonstrated that 3DG-collagen activated GADD153 via phosphorylation of p38 mitogen activated protein kinase (MAPK), and this was dependent on upstream ROS. Inhibition of ROS and/or p38 MAPK abrogated 3DG-collagen induced caspase-3 activation. Our investigations also demonstrated that 3DG-collagen-induced caspase-3 activation did not signal through the canonical receptor for advanced glycation end products (RAGE) but through integrin α1β1. To further verify the role of integrins, neutralization of integrins α1β1 prevented 3DG-collagen-induced upregulation of ROS, GADD153, and caspase-3 activation; suggesting that 3DG-collagen signaling to the fibroblast is dependent on integrins α1β1.Conclusions/SignificanceTaken together, these findings demonstrate for the first time that a RAGE independent mechanism is involved in 3DG-collagen-induced apoptosis. Moreover, the ER stress pathway through activation of Nox4 by integrins α1β1 plays a key role in 3DG-collagen-induced caspase-3 activation, which may play an important role in the pathogenesis of diabetic wounds.

Endoplasmic reticulum stress induces the expression of COX-2 through activation of eIF2α, p38-MAPK and NF-κB in advanced glycation end products stimulated human chondrocytes

“…This report shows AGEs induce ER stress in human chondrocytes, a finding in agreement with previous reports showing that AGEs mediated ER stress in other cell types [36,37]. Iwawaki et al [38] used a transgenic mouse model to monitor ER stress in vivo , and demonstrated that ER stress occurred in a variety of organs such as liver, spleen, brain, and kidney.…”

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

“…Despite the recent studies suggesting a growth stimulating role for p38 MAPK, a majority of the studies performed on p38 MAPK have attributed this kinase to cell stress and reduced proliferation. In support of this, 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.…”

C/EBP homologous protein induces mesangial cell apoptosis under hyperglycemia

“…Thus, induction of CHOP indicates that ER-initiated apoptosis is induced (23) and our previous study revealed that CHOP plays a role in renal injury (18). Caspase-3 is a downstream target of CHOP and the UPR-independent pathways were demonstrated to culminate in executioner caspase-3 activation and apoptosis in a previous study of proteasome inhibitor-mediated apoptosis (24). Caspase-3 is the final caspase of the apoptotic cascade which activates cytolytic enzymes responsible for apoptosis (25).…”