Circular RNA_0037128 aggravates high glucose-induced damage in HK-2 cells via regulation of microRNA-497-5p/nuclear factor of activated T cells 5 axis

Circular RNAs (CircRNAs) were reported to play vital roles in the progression of DN. Herein, the action of circular RNA_0037128 (circ_0037128) was investigated in DN. The level of circ_0037128, microRNA-497-5p (miR-497-5p) and nuclear factor of activated T cells 5 (NFAT5) was determined using quantitative real-time polymerase chain reaction (qRT-PCR). The feature of circ_0037128 was tested by RNase R and Actinomycin D treatment assays. Cell Counting Kit-8 (CCK-8) and 5-ethynyl-2MODIFIER LETTER PRIME-deoxyuridine (EdU) staining assays were conducted to evaluate the proliferation ability. The relative protein expression was determined via Western blot analysis. Levels of the inflammatory cytokines, like tumor necrosis factor alpha (TNF-alpha), interleukin-1 beta (IL-1 beta) and interleukin-6 (IL-6), were assessed by enzyme-linked immunosorbent assay (ELISA). Reactive oxygen species (ROS) production, lactate dehydrogenase (LDH) and superoxide dismutase (SOD) activity were determined by the matched kits. Dual-luciferase reporter and RNA immunoprecipitation (RIP) assays were conducted for evaluating the correlation between miR-497-5p and circ_0037128 or NFAT5. Circ_0037128 and NFAT5 were enhanced, while miR-497-5p was weakened in kidney tissues of DN patients and high glucose (HG)-cultured HK-2 cells. Circ_0037128 inhibition bated HG-caused inhibition effect on cell proliferation and promotion effects on oxidative stress, inflammation and fibrosis in HK-2 cells. Moreover, circ_0037128 knockdown alleviated HG-caused cell damage via regulating miR-497-5p. In addition, NFAT5 overexpression could reverse the influence of miR-497-5p on HG-induced injury in HK-2 cells. Mechanically, circ_0037128 sponged miR-497-5p to modulate NFAT5. Circ_0037128 downregulation could mitigate HG-stimulated cell damage via regulating the miR-497-5p/NFAT5 axis in HK-2 cells in vitro, providing a possible therapy target for DN.