Objective. Sepsis and associated acute kidney injury (SAKI) are determined to be closely related to poor prognosis. Because the metabolic alterations of tubular epithelial cells (TECs) are crucial for the occurrence and development of SAKI, we carried out this present study to identify the metabolism changes of TECs during SAKI and relevant mechanisms. Methods. Rat SAKI model and rat tubular epithelial cell line were used in our study. ELISA was used to determine the serum cytokines levels. Protein expressions were examined with Western-Blotting and the transcriptions of RNAs were determined with qRT-PCR. ADP/ATP assay and Oil Red O staining were used to examine the energy and lipid metabolism, respectively. Dual-luciferase reporter assay was carried out to determine the interactions between miRNA and specific proteins. Cell cycle arrest and apoptosis were determined with flow cytometry. Results. Sepsis and AKI were induced 12 h after CLP. Energy and lipid metabolism reduced significantly while FOXO1 levels increased remarkably in TECs during SAKI. The expressions of both AKT and CDK2 and the transcriptions of relevant mRNAs reduced significantly in TECs during SAKI while miR-21-3p expression increased remarkably. Both AKT and CDK2 were determined as the direct targets of miR-21-3p. Furthermore, by in vitro experiments, it was demonstrated that FOXO1 levels were regulated by miR-21-3p in TECs via AKT/CDK2 and AKT/CDK2-FOXO1 pathway was crucial in the regulations of miR-21-3p on lipid metabolism, cell cycle arrest, and apoptosis of TECs. Conclusions. MiR-21-3p mediates metabolism and cell fate alterations of TECs via manipulating AKT/CDK2-FOXO1 pathway, and that is crucial in the regulation of energy metabolism of TECs during SAKI.

Background: The morbidity of sepsis induced acute kidney injury remains unacceptable high and the mechanisms of that disease remains unclear. For urine backleak and intercellular tight junction among tubular epithelial cells (TECs) destruction often occur during sepsis induced acute kidney injury, we examined whether lipopolysaccharide could damage intercellular tight junction among TECs and associated mechanisms in our present study.Methods: HK-2 cells were cultured, transfected with different SiRNAs and stimulated with LPS and PYR-41. Transepithelial Permeability Assay and Transepithelial Electrical Resistance Assay were used to evaluate intercellular tight junction destruction and Western Blot and Immunofluorescence were used to evaluate proteins expression.Results: Transepithelial Permeability increased significantly (P<0.05) and Transepithelial Electrical Resistance reduced remarkably (P<0.05) of the monolayer TECs stimulated with LPS. The expression of JAM-3 and RhoT1 decreased significantly (P<0.05) in TECs stimulated with LPS, while the level of SMAD-4 increased significantly (P<0.05). Downregulation of the expression of SMAD-4 with RNA interference could increase the expression of JAM-3 in LPS treated TECs. Moreover, upregulation of RhoT1 level by decreased the degradation of RhoT1 could decrease the expression of SMAD-4 and increase the JAM-3 level in TECs treated with LPS, while downregulation of RhoT1 level with RNA interference had the opposite effects.Conclusion: LPS mediates intercellular tight junction destruction among TECs and RhoT1/SMAD-4/JAM-3 is a pivotal pathway to mediate the phenomenon.