Transcriptome analysis and weighted gene co-expression network reveal candidate genes and pathways responses to lactate dehydrogenase inhibition (oxamate) in hyperglycemic human renal proximal epithelial tubular cells

Diabetic kidney disease (DKD) is the leading cause of both chronic kidney disease (CKD) and end-stage renal disease (ESRD). In this study, we performed transcriptome gene expression profiling of kidney tissues in human renal proximal epithelial tubular cell line (HK-2) treated with high D-glucose (HG) for 7 days before the addition of 40 mM oxamate for a further 24 hours in the presence of HG. Afterwards, we analyzed the differentially expressed (DE) genes and investigated gene relationships based on weighted gene co-expression network analysis (WGCNA). Accordingly, enrichment analyses of GO terms and KEGG pathways showed that several pathways (e.g., lysosome (hsa04142) and p53 signaling pathway (hsa04115)) may be involved in a response of HK-2 cells to oxamate. Moreover, via WGCNA, we identified two modules: both the turquoise and blue modules were enriched in pathways associated with lysosome. However, the P53 signaling pathway was only found using all 3,884 DE genes. Furthermore, the key hub genes IGFBP3 interacted with 6 up-regulated and 12 down-regulated DE genes in the network that were enriched in the P53 signaling pathway. This is the first study reporting co-expression patterns of a gene network after lactate dehydrogenase inhibition in HK-2 cells. Our results may contribute to our understanding of the underlying molecular mechanism of in vitro reprogramming under hyperglycemic stress that orchestrates the survival and functions of HK-2 cells. Six replicates of HK-2 cells were firstly exposed to HG treatments for seven days, then three replicates of them were exposed 40 mM oxamate (case group), while the other three replicates were still under the same HG condition but 40 mM oxamate expose (control group). Unfortunately, one replicate of case group failed in RNA sample preparation, so five replicates of cells were finally chosen for RNA sequencing in this study.