Transcriptomic and proteomic changes in human mesangial and proximal tubule epithelial cells in model hyperglycemia – effect of glyoxalase 1 inducer

Abstract

Diabetic nephropathy is a major microvascular complication of diabetes mellitus that develops in approximately 40% of patients with diabetes. Diabetes-associated hyperglycemia drives low grade inflammation and dysfunction of renal cells leading to disease manifestation. Increased flux and metabolism of glucose by hexokinase-2 (HK2), circumventing substrate saturation of this enzyme in normoglycemia by glucose-induced stabilization to proteolysis, leads to the accumulation of glycolytic intermediates in unscheduled glycolysis. This leads to: mitochondrial dysfunction and oxidative stress; increased reactive metabolite, methylglyoxal – also called dicarbonyl stress - causing glycation, formation of advanced glycation end-products (AGEs) and related protein misfolding linked to low grade inflammation and cellular dysfunction; and activation of hexosamine and protein kinase C pathways. The aim of this work was to explore the transcriptomic and proteomics changes induced by high glucose concentration, as a model of hyperglycemia, in human mesangial cells (MGCs) and proximal tubular epithelial cells (RPTECs) and the effect of treatment with trans-resveratrol and hesperetin combination, known as glyoxalase 1 (Glo1) inducer, on both profiles. The working hypothesis is that high glucose concentration induces HK2-linked glycolytic overload in MES and PTEC, with transcriptomic and proteomics changes linked to cell dysfunction found in diabetic nephropathy which may be corrected by Glo1 inducer. We found evidence to support the establishment of HK2-linked glycolytic overload in high glucose concentration – increased HK2 protein without increase in protein abundance of other glycolytic enzymes in early-stage glycolysis. Pathways enrichment analysis in MGCs showed increased protein abundances of ubiquitination, proteasome degradation and tRNA processing – consistent with increased proteolytic processing of MG-modified misfolded proteins and increased protein synthesis in replacement. All pathway enrichment in high glucose concentration was corrected by Glo1 inducer. Pathways enrichment analysis in RPTECs showed increased protein abundances of protein folding and CCT/TriC chaperone complexes, Nrf2 and cell response to stress and metabolism of proteins. All pathway enrichment in high glucose concentration was corrected by Glo1 inducer. Glo1 inducer also decreased cell senescence and senescence associated secretory phenotype in both low and high glucose concentrations, suggesting an anti-senescence effect. This uncovers the changes in gene expression and protein profile changes in renal cells induced by high glucose which may contribute to cellular dysfunction and progression of diabetic nephropathy. The effects of Glo1 inducer suggest this supplementation may have benefit in the treatment and slowing the progression of diabetic nephropathy.

Date of Award	2023
Original language	American English
Awarding Institution	HBKU College of Health & Life Sciences