RESUMO
Long non-coding RNAs (lncRNAs) are a group of epigenetic regulators that have been implicated in kidney diseases including acute kidney injury (AKI). However, very little is known about the specific lncRNAs involved in AKI and the mechanisms underlying their pathologic roles. Here, we report a new lncRNA derived from the pseudogene GSTM3P1, which mediates ischemic AKI by interacting with and promoting the degradation of mir-668, a kidney-protective microRNA. GSTM3P1 and its mouse orthologue Gstm2-ps1 were induced by hypoxia in cultured kidney proximal tubular cells. In mouse kidneys, Gstm2-ps1 was significantly upregulated in proximal tubules at an early stage of ischemic AKI. This transient induction of Gstm2-ps1 depends on G3BP1, a key component in stress granules. GSTM3P1 overexpression increased kidney proximal tubular apoptosis after ATP depletion, which was rescued by mir-668. Notably, kidney proximal tubule-specific knockout of Gstm2-ps1 protected mice from ischemic AKI, as evidenced by improved kidney function, diminished tubular damage and apoptosis, and reduced kidney injury biomarker (NGAL) induction. To test the therapeutic potential, Gstm2-ps1 siRNAs were introduced into cultured mouse proximal tubular cells or administered to mice. In cultured cells, Gstm2-ps1 knockdown suppressed ATP depletion-associated apoptosis. In mice, Gstm2-ps1 knockdown ameliorated ischemic AKI. Mechanistically, both GSTM3P1 and Gstm2-ps1 possessed mir-668 binding sites and downregulated the mature form of mir-668. Specifically, GSTM3P1 directly bound to mature mir-668 to induce its decay via target-directed microRNA degradation. Thus, our results identify GSTM3P1 as a novel lncRNA that promotes kidney tubular cell death in AKI by binding mir-668 to inducing its degradation.
Assuntos
Injúria Renal Aguda , Apoptose , Túbulos Renais Proximais , MicroRNAs , Pseudogenes , RNA Longo não Codificante , Animais , Humanos , Masculino , Camundongos , Injúria Renal Aguda/genética , Injúria Renal Aguda/patologia , Injúria Renal Aguda/metabolismo , Injúria Renal Aguda/etiologia , Apoptose/genética , Modelos Animais de Doenças , Isquemia/genética , Isquemia/metabolismo , Isquemia/patologia , Túbulos Renais Proximais/metabolismo , Túbulos Renais Proximais/patologia , Camundongos Endogâmicos C57BL , Camundongos Knockout , MicroRNAs/metabolismo , MicroRNAs/genética , Pseudogenes/genética , Estabilidade de RNA , RNA Longo não Codificante/genética , RNA Longo não Codificante/metabolismoRESUMO
Extracellular vesicles from stem cells or progenitor cells are novel therapeutic systems for acute kidney injury. With exosomes (the smallest class of extracellular vesicles), Viñas et al. successfully rescued ischemic injured kidney. MicroRNA-486-5p, the crucial factor specifically delivered by exosomes to kidney, ameliorates the injury by targeting phosphatase and tensin homolog and inhibiting endothelial cell apoptosis. In this commentary, we discuss the potential underlying mechanism and the pivotal impact of their study on extracellular vesicle therapy.
Assuntos
Exossomos , Vesículas Extracelulares , MicroRNAs , Células Endoteliais , Humanos , RimRESUMO
The pathogenesis of ischemic diseases remains unclear. Here we demonstrate the induction of microRNA-668 (miR-668) in ischemic acute kidney injury (AKI) in human patients, mice, and renal tubular cells. The induction was HIF-1 dependent, as HIF-1 deficiency in cells and kidney proximal tubules attenuated miR-668 expression. We further identified a functional HIF-1 binding site in the miR-668 gene promoter. Anti-miR-668 increased apoptosis in renal tubular cells and enhanced ischemic AKI in mice, whereas miR-668 mimic was protective. Mechanistically, anti-miR-668 induced mitochondrial fragmentation, whereas miR-668 blocked mitochondrial fragmentation during hypoxia. We analyzed miR-668 target genes through immunoprecipitation of microRNA-induced silencing complexes followed by RNA deep sequencing and identified 124 protein-coding genes as likely targets of miR-668. Among these genes, only mitochondrial protein 18 kDa (MTP18) has been implicated in mitochondrial dynamics. In renal cells and mouse kidneys, miR-668 mimic suppressed MTP18, whereas anti-miR-668 increased MTP18 expression. Luciferase microRNA target reporter assay further verified MTP18 as a direct target of miR-668. In renal tubular cells, knockdown of MTP18 suppressed mitochondrial fragmentation and apoptosis. Together, the results suggest that miR-668 is induced via HIF-1 in ischemic AKI and that, upon induction, miR-668 represses MTP18 to preserve mitochondrial dynamics for renal tubular cell survival and kidney protection.