MicroRNA-30a inhibits cell proliferation in a sepsis-induced acute kidney injury model by targeting the YAP-TEAD complex.

BACKGROUND: Acute kidney injury (AKI) is a primary feature of renal complications in patients with sepsis. MicroRNA (miRNA/miR)-30a is an essential regulator of cardiovascular diseases, tumors, phagocytosis, and other physical processes, but whether it participates in sepsis-induced AKI (sepsis-AKI) is unknown. We aimed to elucidate the functions and molecular mechanism underlying miR-30a activity in sepsis-AKI.

METHODS: The classical cecal ligation and puncture (CLP) method and lipopolysaccharide (LPS)-induced Human Kidney 2 (HK-2) cells were used to establish in vivo and in vitro sepsis-AKI models. Specific pathogen-free and mature male Sprague-Dawley (SD) rats, aged 6-8 weeks (weight 200-250 g), were randomly divided into five-time phase subgroups. Fluid resuscitation with 30 mL/kg 37 °C saline was administered after the operation, without antibiotics. Formalin-fixed, paraffin-embedded kidney sections were stained with hematoxylin and eosin. SD rat kidney tissue samples were collected for analysis by real-time quantitative polymerase chain reaction and enzyme-linked immunosorbent assay. HK-2 cells were transfected with hsa-miR-30a-3p mimics or inhibitors, and compared with untreated normal controls. RNA, protein, and cell viability were evaluated by quantitative reverse transcription-polymerase chain reaction (qRT-PCR), western blot, and cell counting kit-8 methods. A Dual-Luciferase Assay Kit (Promega) was used to measure luciferase activity 48 h after transfection with miR-30a-3p mimics.

RESULTS: Expression levels of miR-30a-3p and miR-30a-5p in renal tissues of the sepsis group were significantly reduced at 12 h and 24 h ( P <0.05). Tumor necrosis factor-α (TNF-α) and interleukin-1β (IL-1β) were significantly increased in renal tissue 3 h after the operation in rats ( P <0.05), and gradually decreased 6 h, 12 h, and 24 h after CLP. Levels of miR-30a-5p and miR-30a-3p were significantly down-regulated at 3 h after LPS treatment ( P <0.05), and gradually decreased in HK-2 cells. One hour after LPS (10 µg/mL) treatment, TNF-α and IL-1β levels in HK-2 cells were significantly up-regulated ( P < 0.05), and they were markedly down-regulated after 3 h ( P <0.05). IL-6 expression levels began to rise after LPS treatment of cells, peaked at 6 h ( P <0.05), and then decreased to the initial level within a few hours. Stimulation with 10 µg/mL LPS promoted HK-2 cells proliferation, which was inhibited after miR-30a-3p-mimic transfection. Bioinformatics prediction identified 37 potential miR-30a-3p target genes, including transcriptional enhanced associate domain 1 ( TEAD1 ). After transfection of HK-2 cells with miR-30a-3p mimics and miR-30a-3p inhibitor, TEAD1 transcript was significantly up- and down-regulated, respectively (both P <0.05). After LPS treatment (24 h), expression of TEAD1 in the inhibitors group was significantly increased ( P <0.01), while that in the mimics group was significantly suppressed ( P <0.01). In the dual luciferase reporter experiment, miR-30a-3p overexpression decreased fluorescence intensity ( P <0.01) from TEAD1-wt -containing plasmids, but did not influence fluorescence intensity from TEAD1-muta -containing plasmids. LPS may promote HK-2 cells proliferation through the miR-30a-3p/ TEAD1 pathway.

CONCLUSION: In a background of expression of inflammatory factors, including TNF-α, IL-1β, and IL-6, which were transiently increased in the sepsis-AKI model, miR-30a was down-regulated. Down-regulated miR-30a-3p may promote cell proliferation by targeting TEAD1 in LPS-induced HK-2 cells, demonstrating its potential as a biomarker for early sepsis-AKI diagnosis.