ABSTRACT
Myocardial injury and dysfunction are critical manifestations of sepsis. Previous studies have reported that liver X receptor (LXR) activation is protective during sepsis. However, whether LXR activation protects against septic heart injury and its underlying mechanisms remain elusive. This study was designed to determine the role of LXR activation in the septic heart with a focus on SIRT1 (silent information regulator 1) signaling. Male cardiac-specific SIRT1 knockout mice (SIRT1-/-) and their wild-type littermates were subjected to sepsis by cecal ligation and puncture (CLP) in the presence or absence of LXR agonist T0901317. The survival rate of mice was recorded during the 7-day period post CLP. Our results demonstrated that SIRT1-/- mice suffered from exacerbated mortality and myocardial injury in comparison with their wild-type littermates. Meanwhile, T0901317 treatment improved mice survival, accompanied by significant ameliorations of myocardial injury and dysfunction in wild-type mice but not in SIRT1-/- mice. Furthermore, the levels of myocardial inflammatory cytokines (TNF-α, IL-6, IL-1ß, MCP-1, MPO and HMGB1), oxidative stress (ROS generation, MDA), endoplasmic-reticulum (ER) stress (protein levels of CHOP, GRP78, GRP94, IRE1α, and ATF6), and cardiac apoptosis following CLP were inhibited by T0901317 treatment in wild-type mice but not in SIRT1-/- mice. Mechanistically, T0901317 enhanced SIRT1 signaling and the subsequent deacetylation and activation of antioxidative FoxO1 and anti-ER stress HSF1, as well as the deacetylation and inhibition of pro-inflammatory NF-ΚB and pro-apoptotic P53, thereby alleviating sepsis-induced myocardial injury and dysfunction. Our data support the promise of LXR activation as an effective strategy for relieving heart septic injury.
Subject(s)
Anticholesteremic Agents/pharmacology , Heart Injuries/drug therapy , Hydrocarbons, Fluorinated/pharmacology , Liver X Receptors/genetics , Sepsis/drug therapy , Sirtuin 1/genetics , Sulfonamides/pharmacology , Animals , Chemokine CCL2/genetics , Chemokine CCL2/metabolism , Endoplasmic Reticulum Chaperone BiP , Forkhead Box Protein O1/genetics , Forkhead Box Protein O1/metabolism , Gene Expression Regulation , HMGB1 Protein/genetics , HMGB1 Protein/metabolism , Heart Injuries/genetics , Heart Injuries/mortality , Heart Injuries/pathology , Heat Shock Transcription Factors/genetics , Heat Shock Transcription Factors/metabolism , Heat-Shock Proteins/genetics , Heat-Shock Proteins/metabolism , Interleukin-1beta/genetics , Interleukin-1beta/metabolism , Interleukin-6/genetics , Interleukin-6/metabolism , Liver X Receptors/agonists , Liver X Receptors/metabolism , Male , Mice , Mice, Knockout , Myocardium/metabolism , Myocardium/pathology , Peroxidase/genetics , Peroxidase/metabolism , Sepsis/genetics , Sepsis/mortality , Sepsis/pathology , Signal Transduction , Sirtuin 1/deficiency , Survival Analysis , Transcription Factor CHOP/genetics , Transcription Factor CHOP/metabolism , Tumor Necrosis Factor-alpha/genetics , Tumor Necrosis Factor-alpha/metabolismABSTRACT
BACKGROUND AND AIMS: Aberrant upregulation of POU2F2 expression has been discovered in metastatic gastric cancer (GC). However, the mechanisms underlying the aberrant upregulation and the potential functions of POU2F2 remain uncertain. DESIGN: The role and mechanism of POU2F2 in GC metastasis were investigated in gastric epithelial cells, GC cell lines and an experimental metastasis animal model by gain of function and loss of function. Upstream and downstream targets of POU2F2 were selected by bioinformatics and identified by luciferase reporter assay, electrophoretic mobility shift assay and chromatin immunoprecipitation PCR. The influence of miR-218 on its putative target genes (POU2F2, ROBO1 and IKK-ß) and GC metastasis was further explored via in vitro and in vivo approaches. RESULTS: Increased POU2F2 expression was detected in metastatic GC cell lines and patient samples. POU2F2 was induced by the activation of nuclear factor (NF)-κB and, in turn, regulated ROBO1 transcription, thus functionally contributing to GC metastasis. Finally, miR-218 was found to suppress GC metastasis by simultaneously mediating multiple molecules in the POU2F2-oriented network. CONCLUSIONS: This study demonstrated that NF-κB and the SLIT2/ROBO1 interaction network with POU2F2 as the central part may exert critical effects on tumour metastasis. Blocking the activation of the POU2F2-oriented metastasis network using miR-218 precursors exemplified a promising approach that sheds light on new strategies for GC treatment.
