Epigenetic mechanism of LncRNA KCNQ1OT1 in high-glucose-induced podocyte injury via m6A methylation modification.

Podocyte injury is a hallmark of diabetic nephropathy associated with proteinuria and renal dysfunction. This study elucidated the role of long non-coding RNA KCNQ1 overlapping transcript 1 (LncRNA KCNQ1OT1) in high-glucose (HG)-induced podocyte injury. In HG-treated podocytes, KCNQ1OT1, WTAP, and MAPK6 were quantified. After KCNQ1OT1 interference, cell viability, apoptosis, inflammation, and oxidative stress were measured. Subcellular localization of KCNQ1OT1 was determined by nuclear-cytoplasmic fractionation and RNA FISH. Binding of MLL1 to KCNQ1OT1 was validated via RNA pull-down and RIP. MLL1/H3K4me3 enrichment on the WTAP promoter was detected by ChIP. m6A levels of MAPK6 were measured by MeRIP. Binding of IGF2BP1 to MAPK6 was confirmed via RIP. Rescue experiments explored the WTAP/MAPK6 axis in podocyte injury. HG treatment upregulated KCNQ1OT1, WTAP, and MAPK6 in podocytes. KCNQ1OT1 knockdown enhanced cell proliferation, reduced apoptosis, and attenuated inflammation and oxidative stress. Mechanistically, nuclear-localized KCNQ1OT1 recruited MLL1 to the WTAP promoter, enhancing H3K4me3 modification and WTAP activation. WTAP promoted m6A methylation of MAPK6 mRNA, which was stabilized by IGF2BP1. Overexpression of WTAP or MAPK6 abrogated the protective effects of KCNQ1OT1 knockdown on podocytes injury. In conclusions, KCNQ1OT1 exacerbates HG-induced podocyte injury by upregulating the WTAP/MAPK6 axis in an m6A-dependent manner.