Methylglyoxal down-regulates the expression of cell cycle associated genes and activates the p53 pathway in human umbilical vein endothelial cells

Abstract

Although methylglyoxal (MGO) has emerged as key mediator of diabetic microvascular complications, the influence of MGO on the vascular transcriptome has not thoroughly been assessed. Since diabetes is associated with low grade inflammation causing sustained nuclear factor-kappa B (NF-κB) activation, the current study addressed 1) to what extent MGO changes the transcriptome of human umbilical vein endothelial cells (HUVECs) exposed to an inflammatory milieu, 2) what are the dominant pathways by which these changes occur and 3) to what extent is this affected by carnosine, a putative scavenger of MGO. Microarray analysis revealed that exposure of HUVECs to high MGO concentrations significantly changes gene expression, characterized by prominent down-regulation of cell cycle associated genes and up-regulation of heme oxygenase-1 (HO-1). KEGG-based pathway analysis identified six significantly enriched pathways of which the p53 pathway was the most affected. No significant enrichment of inflammatory pathways was found, yet, MGO did inhibit VCAM-1 expression in Western blot analysis. Carnosine significantly counteracted MGO-mediated changes in a subset of differentially expressed genes. Collectively, our results suggest that MGO initiates distinct transcriptional changes in cell cycle/apoptosis genes, which may explain MGO toxicity at high concentrations. MGO did not augment TNF-α induced inflammation.

Methylglyoxal induces nuclear accumulation of p53 and γH2AX in normal and cancer cells

“…This upregulation of nuclear phospho-p53 seems not accompanied with an increase in apoptosis rate but will likely activate p53 dependent signaling pathways. This would fit with recently published data showing an activation of the p53 pathway upon MGO treatment in human umbilical vein endothelial cells (HUVECs) [31]. Moreover, it was shown that the total amount of nuclear p53 is increased in hepatocellular carcinoma cells upon MGO treatment.…”

“…In cell culture model systems often near toxic concentrations of MGO ranging from 50 µM up to 2 mM MGO are applied. For instance, HUVEC cells were treated with up to 800 µM MGO to copy injuries in endothelial cells typically seen in diabetes patients knowing that these concentrations do not reflect the plasma concentrations of MGO even in diabetes patients [31]. The authors argued that the in vivo situation is rather a complex mixture of compounds acting in synergy than a single compound leading to this phenotype [31].…”

“…For instance, HUVEC cells were treated with up to 800 µM MGO to copy injuries in endothelial cells typically seen in diabetes patients knowing that these concentrations do not reflect the plasma concentrations of MGO even in diabetes patients [31]. The authors argued that the in vivo situation is rather a complex mixture of compounds acting in synergy than a single compound leading to this phenotype [31]. In addition, the application of MGO in cell culture is different compared to the in vivo situation and thereby MGO can act more direct on the cells.…”

Mapping metabolic oscillations during cell cycle progression

“…A glutathione peak and a putative methylglyoxal peak were also detected in these samples (Figure 3d), and were also somewhat more abundant in G1. These results suggest that methylglyoxal metabolism may be cell-cycle associated, consistent with reports that methylglyoxal treatment of cells can cause cell cycle arrest (37)(38)(39).…”

Glycation Leads to Increased Polysialylation and Promotes the Metastatic Potential of Neuroblastoma Cells

“…In this context it would be also important to know, how MGO or glycation alter the expression of polysialyltransferases. Although recent studies demonstrate that MGO alters gene expression profiles [24], the mechanism how MGO interfere with transcription is still unknown. It is conceivable that glycation of transcription factors is the major cause for this observation.…”