Transcription Factor ChREBP Mediates High Glucose-Evoked Increase in HIF-1α Content in Epithelial Cells of Renal Proximal Tubules.
Aleksandra OwczarekKatarzyna B GieczewskaRobert JarzynaZuzanna FrydzinskaKatarzyna WiniarskaPublished in: International journal of molecular sciences (2021)
Hyperglycemia/diabetes appears to be accompanied by the state of hypoxia, which especially affects kidneys. The aim of the study was to elucidate the mechanism of high glucose action on HIF-1α expression in renal proximal tubule epithelial cells. The research hypotheses included: (1) the participation of transcription factor ChREBP; and (2) the involvement of the effects resulting from pseudohypoxia, i.e., lowered intracellular NAD+/NADH ratio. The experiments were performed on HK-2 cells and primary cells: D-RPTEC (Diseased Human Renal Proximal Tubule Epithelial Cells-Diabetes Type II) and RPTEC (Renal Proximal Tubule Epithelial Cells). Protein and mRNA contents were determined by Western blot and RT-qPCR, respectively. ChREBP binding to DNA was detected applying chromatin immunoprecipitation, followed by RT-qPCR. Gene knockdown was performed using siRNA. Sirtuin activity and NAD + /NADH ratio were measured with commercially available kits. It was found that high glucose in HK-2 cells incubated under normoxic conditions: (1) activated transcription of HIF-1 target genes, elevated HIF-1α and ChREBP content, and increased the efficacy of ChREBP binding to promoter region of HIF1A gene; and (2), although it lowered NAD + /NADH ratio, it affected neither sirtuin activity nor HIF-1α acetylation level. The stimulatory effect of high glucose on HIF-1α expression was not observed upon the knockdown of ChREBP encoding gene. Experiments on RPTEC and D-RPTEC cells demonstrated that HIF-1α content in diabetic proximal tubular cells was lower than that in normal ones but remained high glucose-sensitive, and the latter phenomenon was mediated by ChREBP. Thus, it is concluded that the mechanism of high glucose-evoked increase in HIF-1α content in renal proximal tubule endothelial cells involves activation of ChREBP, indirectly capable of HIF1A gene up-regulation.
Keyphrases
- high glucose
- endothelial cells
- induced apoptosis
- transcription factor
- vascular endothelial growth factor
- cell cycle arrest
- genome wide
- type diabetes
- endoplasmic reticulum stress
- gene expression
- genome wide identification
- dna methylation
- copy number
- poor prognosis
- dna damage
- oxidative stress
- metabolic syndrome
- dna binding
- small molecule
- binding protein
- skeletal muscle
- long non coding rna
- insulin resistance
- genome wide analysis
- glycemic control