Previous studies reported that LncRNAs were involved in the progression of ischemic AKI[35, 36].In present study, we found that LncRNA ENSMUST_147219 mediated the I/R induced the renal cell apoptosis. Mechanistically, LncRNA ENSMUST_147219 sponged the miR-221-5p and then upregulated the expression of IRF6. Finally, knock down of LncRNA ENSMUST_147219 ameliorated that ischemic AKI via regulation of miR-221-5p/IRF6 axis. Collectively, the data suggested that LncRNA ENSMUST_147219 promoted the progression of ischemic AKI.
Several studies reported that LncRNAs regulated the progression of ischemic AKI. One study found that I/R induced the renal cell apoptosis was suppressed by TUG[16]. Others studies showed that I/R induced the renal cell apoptosis was mediated by LncRNA MEG3, Lnc NEAT1, Lnc GAS5, and LncRNA H19[17–20]. In the current study, we revealed that LncENSMUST_147219 also mediated the I/R-induced the renal cell apoptosis (Fig. 1). Specifically, I/R-induced renal cell apoptosis and the activation of caspase-3 was attenuated by the knockdown of LncRNA ENSMUST_147219 (Fig. 2), however, this effect was enhanced by the overexpression of LncRNA ENSMUST_147219(Fig. 3). In addition, knockdown of ENSMUST_147219 ameliorated the renal cell apoptosis in I/R induced AKI (Figs. 8). Taken altogether, the data demonstrated that LncRNA ENSMUST_147219 was apoptosis inducer in ischemic AKI.
LncRNAs served as ceRNA to sponge miRNAs to regulate associated gene expression[37]. In current study, we demonstrated that miR-221-5p was target of LncRNA ENSMUST_147219, which was supported by the following evidences: 1) The prediction and dual-luciferase reporter assays showed that LncRNA ENSMUST_147219 binds to miR-221-5p (Fig. 4A&B). 2) The RNA-FISH colocalization of LncRNA ENSMUST_147219 and miR-221-5p supported the finding of dual-luciferase reporter assays (Figs. 4C&D). 3) RT-qPCR results found that LncRNA ENSMUST_147219 negatively regulated the expression of miR-221-5p (Figs. 4E &F). Collectively, the data supported that LncRNA ENSMUST_147219 sponged the miR-221-5p.
Several studies showed that miR-221-5p was apoptosis suppressor.[38, 39] In the present study, our data found that miR-221-5p also suppressed the I/R-induced renal cell apoptosis (Fig. 5). Previous studies showed that IRF6 was an apoptosis inducer [40, 41]. The dual-luciferase reporter assays found that IRF6 was a target of miR-221-5p(Figs. 6A&B). We further found that miR-221-5p mimics inhibited the mRNA and protein expression of IRF6, respectively (Figs. 6C&D). Previous study indicated that IRF6 mediated renal clear cell carcinoma cell apoptosis[34]. Consistently, we found that IRF6 also mediated the renal cell apoptosis (Fig. 6E&H). Interestingly, we further confirmed that miR-221-5p was proapoptotic function mediator of LncRNA ENSMUST_147219 (Fig. 7). In addition, knock down of LncRNA ENSMUST_1472 19 attenuated ischemic mice AKI by regulation of miR-221-5p/ IRF6 pathway. Collectively, the data suggest that LncRNA ENSMUST_147219/miR-221-5p/ IRF6 axis mediated the I/R-induced renal cell apoptosis.
In summary, we found that LncRNA ENSMUST_147219 was an apoptosis inducer during ischemic injury. Mechanistically, LncRNA ENSMUST_147219 sponged miR-221-5p and then increased the expression of IRF6. Finally, suppression of LncRNA ENSMUST_147219 attenuated ischemic AKI via targeting the miR-221-5p/IRF6 axis. Collectively, our data found that LncRNA ENSMUST_147219 was a novel therapeutic target for ischemic AKI.