GADD45a Promotes Active DNA Demethylation of the MMP-9 Promoter via Base Excision Repair Pathway in AGEs-Treated Keratinocytes and in Diabetic Male Rat Skin

Abstract

Diabetes elevates matrix metalloproteinase (MMP)-9 levels in the skin and its keratinocytes, and activated MMP-9 impairs skin wound healing. Epigenetic regulation of the DNA methylation status within the MMP-9 promoter plays an important role in the alteration of MMP-9 expression. Our aim was to investigate the role and mechanism of growth arrest and DNA damage-inducible 45a (GADD45a), a well-known DNA demethylation regulatory protein that mediates DNA methylation, in the regulation of MMP-9 expression. In this study, we showed that GADD45a was markedly upregulated in skin tissues from patients with diabetic foot ulcers, in diabetic rats, and in human keratinocyte (HaCaT) cells exposed to advanced glycation end products. We observed a substantial positive correlation between the levels of GADD45a and MMP-9 expression. Knockdown of GADD45a ameliorated the increase in MMP-9 transcription induced by a diabetic condition by inhibiting demethylation in the MMP-9 promoter and promoted diabetic HaCaT cell migration, but GADD45a knockdown did not affect HaCaT cell proliferation or apoptosis. Additionally, we demonstrated that overexpression of GADD45a activated MMP-9 expression by inducing promoter demethylation. Moreover, we found that GADD45a binds to the promoter of MMP-9 and recruits thymine-DNA glycosylase for base excision repair-mediated demethylation in diabetic HaCaT cells and diabetic rat skin. Our results reveal a mechanism in which GADD45a is required for demethylation of the MMP-9 promoter and the induction of diabetic wound healing. The inhibition of GADD45a might be a therapeutic strategy for diabetic foot ulcers.

Transcriptome Profiling of Bovine Macrophages Infected by Mycobacterium avium spp. paratuberculosis Depicts Foam Cell and Innate Immune Tolerance Phenotypes

“…DNMT1, which was DE at an advanced stage in MAP-infected JD(-) macrophages, is necessary to establish and maintain DNA methylation patterns (132). GADD45A was strongly downregulated and therefore probably does not favor active DNA demethylation (57). Together, these results suggest the preservation of DNA methylation patterns at the sequence level.…”

“…During the initial "cytokine storm" (section inflammatory processes), the gene expression of DNA methyltransferase 1 (DNMT1), responsible for gene hypermethylation, increased ∼2-fold at 24 hpi (Supplementary Table 4). The growth arrest and DNA-damage-inducible protein 45 alpha (GADD45A) and gamma (GADD45G) genes are members of a small family of stress-response genes and serve as a nexus between DNA repair and epigenetics (57). The GADD45A and GADD45G genes were downregulated from 4 hpi until 24 hpi in MAP-infected JD(-) macrophages ( Supplementary Table 4).…”

Blockade of receptors of advanced glycation end products ameliorates diabetic osteogenesis of adipose‐derived stem cells through DNA methylation and Wnt signalling pathway

“…Diverse studies have shown that AGEs are involved in various tissue pathologies arising from diabetic complications, including vessels, skin, bone, kidney and periodontal tissues . Kume et al reported that fat, cartilage and bone differentiation from MSCs were reduced following artificially supplemented AGEs.…”

Advanced Glycation End Products (AGEs): Biochemistry, Signaling, Analytical Methods, and Epigenetic Effects

“…Recent studies have highlighted the role played by epigenetic mechanisms in the well-studied phenomenon of metabolic memory of diabetes [149]. The pathological effects of hyperglycemia are due to four basic mechanisms: PKC activation, enhanced production of AGEs, enhanced glucose flux due to polyol pathway, and upregulation of hexosamine 11 Oxidative Medicine and Cellular Longevity pathway activity [150,151]. Hyperglycemic status has been associated with the activation of histone modifications that provoke the enhanced expression of inflammatory genes [152].…”