Seon-Jin Lee

TXNIP Deficiency Exacerbates Endotoxic Shock via the Induction of Excessive Nitric Oxide Synthesis

Thioredoxin-interacting protein (TXNIP) has multiple functions, including tumor suppression and involvement in cell proliferation and apoptosis. However, its role in the inflammatory process remains unclear. In this report, we demonstrate that Txnip−/− mice are significantly more susceptible to lipopolysaccharide (LPS)-induced endotoxic shock. In response to LPS, Txnip−/− macrophages produced significantly higher levels of nitric oxide (NO) and inducible nitric oxide synthase (iNOS), and an iNOS inhibitor rescued Txnip−/− mice from endotoxic shock-induced death, demonstrating that NO is a major factor in TXNIP-mediated endotoxic shock. This susceptibility phenotype of Txnip−/− mice occurred despite reduced IL-1β secretion due to increased S-nitrosylation of NLRP3 compared to wild-type controls. Taken together, these data demonstrate that TXNIP is a novel molecule that links NO synthesis and NLRP3 inflammasome activation during endotoxic shock.

NDRG2 and PRA1 interact and synergistically inhibit T-cell factor/β-catenin signaling

NDRG2a and PRA1 colocalize by fluorescence microscopy (View Interaction: 1, 2, 3)

Graphene oxide induces apoptotic cell death in endothelial cells by activating autophagy via calcium-dependent phosphorylation of c-Jun N-terminal kinases.

Despite the rapid expansion of the biomedical applications of graphene oxide (GO), safety issues related to GO, particularly with regard to its effects on vascular endothelial cells (ECs), have been poorly evaluated. To explore possible GO-mediated vasculature cytotoxicity and determine lateral GO size relevance, we constructed four types of GO: micrometer-sized GO (MGO; 1089.9±135.3nm), submicrometer-sized GO (SGO; 390.2±51.4nm), nanometer-sized GO (NGO; 65.5±16.3nm), and graphene quantum dots (GQDs). All types but GQD showed a significant decrease in cellular viability in a dose-dependent manner. Notably, SGO or NGO, but not MGO, potently induced apoptosis while causing no detectable necrosis. Subsequently, SGO or NGO markedly induced autophagy through a process dependent on the c-Jun N-terminal kinase (JNK)-mediated phosphorylation of B-cell lymphoma 2 (Bcl-2), leading to the dissociation of Beclin-1 from the Beclin-1-Bcl-2 complex. Autophagy suppression attenuated the SGO- or NGO-induced apoptotic cell death of ECs, suggesting that SGO- or NGO-induced cytotoxicity is associated with autophagy. Moreover, SGO or NGO significantly induced increased intracellular calcium ion (Ca2+) levels. Intracellular Ca2+ chelation with BAPTA-AM significantly attenuated microtubule-associated protein 1A/1B-light chain 3-II accumulation and JNK phosphorylation, resulting in reduced autophagy. Furthermore, we found that SGO or NGO induced Ca2+ release from the endoplasmic reticulum through the PLC β3/IP3/IP3R signaling axis. These results elucidate the mechanism underlying the size-dependent cytotoxicity of GOs in the vasculature and may facilitate the development of a safer biomedical application of GOs. STATEMENT OF SIGNIFICANCE Graphene oxide (GO) have received considerable attention with respect to their utilization in biomedical applications. However, GO-related safety issues concerning human vasculature are very limited. In this manuscript, we report for the first time the differential size-related biological effects of GOs on endothelial cells (ECs). Notably, Subnanometer- and nanometersized GOs induce apoptotic death in ECs via autophagy activation. We propose a molecular mechanism for the GO-induced autophagic cell death through the PLCβ3/IP3/Ca2+/JNK signaling axis. Our findings could be provide a better understanding of the GO sizedependent cytotoxicity in vasculature and facilitate the future development of safer biomedical applications of GOs.

Draft Genome Sequence of Bacillus oceanisediminis 2691

Bacillus oceanisediminis 2691 is an aerobic, Gram-positive, spore-forming, and moderately halophilic bacterium that was isolated from marine sediment of the Yellow Sea coast of South Korea. Here, we report the draft genome sequence of B. oceanisediminis 2691 that may have an important role in the bioremediation of marine sediment.

Caspase-mediated cleavage and DNase activity of the translation initiation factor 3, subunit G (eIF3g)

Eukaryotic translation initiation factor 3 is composed of 13 subunits (eIF3a through eIF3m) and plays an essential role in translation. During apoptosis, several caspases rapidly down‐regulate protein synthesis by cleaving eIF4G, ‐4B, ‐3j, and ‐2α. In this study, we found that the activation of caspases by cisplatin in T24 cells induces the cleavage of subunit G of the eIF3 complex (eIF3g). The cleavage site (SLRD220G) was identified, and we found that the cleaved N‐terminus was translocated to the nucleus, activating caspase‐3, and that it also showed a strong DNase activity. These data demonstrate the important roles of eIF3g in the translation initiation machinery and in DNA degradation during apoptosis.

Tescalcin expression contributes to invasive and metastatic activity in colorectal cancer.

We reported previously that tescalcin (TESC) levels were higher in tissue and serum from colorectal cancer (CRC) patients and suggested that TESC was a potential oncotarget in CRC. The aim of this study was to investigate the function of TESC in CRC invasion and metastatic potential. TESC expression was knocked down in CRC cells using small interfering RNA (siRNA). The expression of TESC siRNA reduced cell migration and invasion by inhibiting matrix metalloprotease (MMP) and the epithelial-mesenchymal transition (EMT) pathway. RT-PCR and Western blot analysis showed that TESC siRNA induced E-cadherin. Consistently, TESC overexpression in HCT116 (HCT/TESC) cells enhanced cell migration and invasion by activating MMP and the EMT pathway and reducing E-cadherin. The formation of liver metastatic nodules in vivo was strongly increased in mice injected with HCT/TESC cells compared with that in mice injected with HCT/mock cells. This study demonstrates that TESC is involved in cell migration, invasion, and EMT during CRC tumor invasion. These results implicate TESC as a metastatic mediator and provide a biological rationale for the adverse prognosis associated with elevated TESC expression in human CRC.

Corrigendum to “Small Heterodimer Partner Deficiency Increases Inflammatory Liver Injury Through C-X-C motif chemokine ligand 2-Driven Neutrophil Recruitment in Mice”

Although detailed pathophysiological mechanisms of fulminant hepatitis remain elusive, immune cell recruitment with excessive cytokine production is a well-recognized hallmark of the disease. We determined the function of orphan nuclear receptor small heterodimer partner (SHP) in concanavalin A (ConA)-induced hepatitis model. Male C57BL/6 J mice were injected intravenously with either a lethal dose (25 mg/kg) or a sub-lethal dose (15 mg/kg) of ConA. For the C-X-C motif chemokine ligand (CXCL) 2 neutralization study, mice were intravenously administered anti-mouse CXCL2 antibody (100 μg/mouse). Thirty-six hours following lethal dose of ConA administration, 47% wild type (WT) mice were alive, whereas >85% of Shp knockout (KO) were dead. Shp KO mice were highly susceptible to ConA-induced liver injury and exhibited increased liver necrosis upon sub-lethal dose of ConA administration. FACS analysis and immunohistochemical staining showed significantly higher neutrophil infiltration in Shp KO mice, as compared with WT mice. We found that also in the WT situation, Shp expression gradually decreased, while Cxcl2 expression increased until 6 h, and vice versa at 24 h upon ConA-treatment, indicating an inverse correlation between Shp and Cxcl2 expression during ConA-induced hepatitis. Furthermore, in vivo neutralization of CXCL2 with neutralizing antibody reduces ConA-induced plasma ALT and AST levels, hepatocyte death and neutrophil infiltration in Shp KO mice. Collectively, these results confirm that lacking of SHP results in CXCL2-dependent neutrophil infiltration in ConA-induced liver damage. SHP plays a protective, anti-inflammatory role in liver during acute liver inflammation.

Small heterodimer partner negatively regulates C-X-C motif chemokine ligand 2 in hepatocytes during liver inflammation

Recently, we reported that orphan nuclear receptor small heterodimer partner (SHP) is involved in neutrophil recruitment through the regulation of C-X-C motif chemokine ligand 2 (CXCL2) expression in a concanavalin A (ConA)-induced hepatitis model. In the present study, we examined the mechanisms underlying CXCL2 regulation by SHP and the cell types involved in liver inflammation. To this end, either Shp knockout (KO) or wild-type (WT) bone marrow cells were transferred into sublethally-irradiated WT (KO → WT or WT → WT) or Shp KO (KO → KO or WT → KO) recipients, followed by intravenous injection of ConA (20–30 mg/kg) 8 weeks later. The KO recipient groups showed higher ConA-induced lethality than the WT recipient groups. Accordingly, plasma alanine aminotransferase (ALT) and aspartate aminotransferase (AST) levels, and inflammatory cytokine expressions were significantly higher in the KO recipients than in the WT recipients regardless of donor genotype. Massively increased hepatocyte death in KO recipients, as determined by H&E and TUNEL staining, was observed after ConA challenge. Bone marrow chimera experiments and in vitro chemotaxis assay also showed that SHP-deficient hepatocytes have an enhanced ability to recruit neutrophils to the injured liver. In vitro promoter assays showed that SHP is a negative regulator of Cxcl2 transcription by interfering with c-Jun binding to the AP-1 site within the Cxcl2 promoter. Collectively, SHP regulates Cxcl2 transcription in hepatocytes, playing a pivotal role in the recruitment of neutrophils. SHP-targeting strategies may represent alternative approaches to control fulminant hepatitis.

Novel natural killer cell-mediated cancer immunotherapeutic activity of anisomycin against hepatocellular carcinoma cells

Despite advances in the clinical management of hepatocellular carcinoma (HCC), this form of cancer remains the second leading cause of cancer-related death worldwide. Currently, there are few treatment options for advanced HCC. Therefore, novel treatment strategies for HCC are required. Here, we described the promising antitumour effects of anisomycin, which exerts both direct killing effects and natural killer cell (NK)-mediated immunotherapeutic effects in HCC. To better elucidate the mechanisms through which anisomycin mediates its antitumour effects, we performed a genome-scale transcriptional analysis. We found that anisomycin treatment of HCC differentially modulated a broad range of immune regulation-associated genes. Among these immune regulation-associated genes, we found that lymphocyte function-associated antigen-3 (LFA-3, also called CD58), whose expression was significantly increased in anisomycin-treated HCC cells, was a critical player in NK-mediated immunotherapeutic effects. Furthermore major histocompatibility complex molecules class I (MHC-I) on HCC cells were also significantly regulated by treatment of anisomycin. Those adhesion molecules like CD58, MHC-I, and ICAM4 should be important for immune synapse formation between NK cells and HCC cells to boost NK-mediated immunotherapeutic effects. Notably, this is the first report of NK-dependent immunomodulatory effects of anisomycin suggesting anisomycin as a novel therapeutic drug for treatment of HCC.