Adaptor protein HIP-55 promotes macrophage M1 polarization through promoting AP-1 complex activation

Overwhelming macrophage M1 polarization induced by malfunction of the renin-angiotensin-aldosterone system (RAAS) initiates inflammatory responses, which play a crucial role in various cardiovascular diseases. However, the underlying regulatory mechanism remains elusive. Here, we identified adaptor protein HIP-55 as a critical regulator of macrophage M1 polarization. The expression of HIP-55 was upregulated in M1 macrophage induced by Ang II. Overexpression of HIP-55 significantly promoted Ang II-induced macrophage M1 polarization, whereas genetic deletion of HIP-55 inhibited the Ang II-induced macrophage M1 polarization. Mechanistically, HIP-55 facilitated activator protein-1 (AP-1) complex activation induced by Ang II via promoting ERK1/2 and JNK phosphorylation. Moreover, blocking AP-1 complex activation can attenuate the function of HIP-55 in macrophage polarization. Collectively, our results reveal the role of HIP-55 in macrophage polarization and provide potential therapeutic insights for cardiovascular diseases associated with RAAS dysfunction.

[Construction of TRAF6 ubiquitin site 331 mutant colorectal cancer cell stable line and its effect on biological behavior of colorectal cancer cells]

Objective: To investigate the effect of ubiquitin mutation at position 331 of tumor necrosis factor receptor related factor 6 (TRAF6) on the biological characteristics of colorectal cancer cells and its mechanism. Methods: lentivirus wild type (pCDH-3×FLAG-TRAF6) and mutation (pCDH-3×FLAG-TRAF6-331mut) of TRAF6 gene expression plasmid with green fluorescent protein tag were used to infect colorectal cancer cells SW480 and HCT116, respectively. The infection was observed by fluorescence microscope, and the expressions of TRAF6 and TRAF6-331mut in cells was detected by western blot. Cell counting kit-8 (CCK-8) and plate cloning test were used to detect the proliferation ability of colorectal cancer cells in TRAF6 group and TRAF6-331mut group, cell scratch test to detect cell migration, Transwell chamber test to detect cell migration and invasion, immunoprecipitation to detect the ubiquitination of TRAF6 and TRAF6-331mut with ubiquitinof lysine binding sites K48 and K63. Western blot was used to detect the effects of TRAF6 and TRAF6-331mut over expression on the nuclear factor kappa-B (NF-κB) and mitogen activated protein kinase mitogen-activated protein kinase (MAPK)/activating protein-1(AP-1) signal pathway. Results: The successful infection of colorectal cancer cells was observed under fluorescence microscope. Western blot detection showed that TRAF6 and TRAF6-331mut were successfully expressed in colorectal cancer cells. The results of CCK-8 assay showed that on the fourth day, the absorbance values of HCT116 and SW480 cells in TRAF6-331mut group were 1.89±0.39 and 1.88±0.24 respectively, which were lower than those in TRAF6 group (2.09±0.12 and 2.17±0.45, P=0.036 and P=0.011, respectively). The results of plate colony formation assay showed that the number of clones of HCT116 and SW480 cells in TRAF6-331mut group was 120±14 and 85±14 respectively, which was lower than those in TRAF6 group (190±21 and 125±13, P=0.001 and P=0.002, respectively). The results of cell scratch test showed that after 48 hours, the percentage of wound healing distance of HCT116 and SW480 cells in TRAF6-331mut group was (31±12)% and (33±14)%, respectively, which was lower than those in TRAF6 group [(43±13)% and (43±7)%, P=0.005 and 0.009, respectively]. The results of Transwell migration assay showed that the migration numbers of HCT116 and SW480 cells in TRAF6-331mut group were significantly lower than those in TRAF6 group (P<0.001 and P<0.002, respectively). The results of Transwell invasion assay showed that the number of membrane penetration of HCT116 and SW480 cells in TRAF6-331mut group was significantly lower than those in TRAF6 group (P=0.008 and P=0.009, respectively). The results of immunoprecipitation detection showed that the ubiquitin protein of K48 chain pulled by TRAF6-331mut was lower than that of wild type TRAF6 in 293T cells co-transfected with K48 (0.57±0.19), and the ubiquitin protein of K63 chain pulled down by TRAF6-331mut in 293T cells co-transfected with K63 was lower than that of wild type TRAF6 (0.89±0.08, P<0.001). Western blot assay showed that the protein expression levels of NF-κB, p-NF-κB and p-AP-1 in TRAF6-331mut-HCT116 cells were 0.63±0.08, 0.42±0.08 and 0.60±0.07 respectively, which were lower than those in TRAF6-HCT116 cells (P=0.002, P<0.001 and P<0.001, respectively). The expression level of AP-1 protein in TRAF6-HCT116 cells was 0.89±0.06, compared with that in TRAF6-HCT116 cells. The difference was not statistically significant (P>0.05). The protein expression levels of NF-κB, p-NF-κB and p-AP-1 in TRAF6-331mut-SW480 cells were 0.50±0.06, 0.51±0.04, 0.48±0.02, respectively, which were lower than those in TRAF6-SW480 cells (all P<0.001). There was no significant difference in AP-1 protein expression between TRAF6-331mut-SW480 cells and TRAF6-SW480 cells. Conclusion: The ubiquitin site mutation of TRAF6 gene at 331 may prevent the binding of TRAF6 and ubiquitin lysine sites K48 and K63, and then affect the expressions of proteins related to downstream NF-κB and MAPK/AP-1 signal pathways, and inhibit the proliferation, migration and invasion of colorectal cancer cells.

Effects of Subchronic Aluminum Exposure on Learning, Memory, and Neurotrophic Factors in Rats

Aluminum (Al) is a neurotoxin that gradually accumulates in the brain in human life, resulting in oxidative brain injury related to Alzheimer's disease (AD) and other diseases. In this study, the learning and memory of rats exposed to different aluminum concentrations (0.0 g/L, 2.0 g/L, 4.0 g/L, and 8.0 g/L) were studied, and the learning and memory of rats were observed by shuttle box experiment. With hematoxylin and eosin staining, Western blot, immunofluorescence, and RT-PCR, the morphology of nerve cells in the hippocampus of rat brain were observed, and the levels of activator protein-1 (AP-1) gene and protein, nerve growth factor (NGF), neurotrophin-3 (NT3), glial cell line-derived neurotrophic factor (GDNF), and brain-derived neurotrophic factor (BDNF) gene and protein level, etc. The experimental results showed that subchronic aluminum exposure damaged learning and memory in rats. The cognitive function damage in rats was more evident after increasing the aluminum intake dose. The more aluminum intake, the more pronounced the histological changes in the hippocampus will be. The expression level and protein content of neurotrophic factors in the hippocampus of rats showed a negative correlation with aluminum intake. In this experiment, we explored the mechanism of aluminum exposure in learning and memory disorders, and provided some data reference for further elucidation of the damage mechanism of aluminum on the nervous system and subsequent preventive measures.

CgIL17-5 regulates the mRNA expressions of immune effectors through inducing the phosphorylation of CgMAPKs and the nuclear translocation of CgRel and CgAP-1 in the Pacific oyster Crassostrea gigas

Interleukin-17 (IL-17) is a classic pro-inflammatory cytokine that plays an important role in the immune and inflammatory response. In the present study, the sequence feature of CgIL17-5 and its function as a pro-inflammatory factor in inducing the mRNA expressions of downstream immune effectors were investigated in oyster Crassostrea gigas. There were two tightly folded alpha helixes and two pairs of antiparallel beta-pleated sheet in the amino acid sequence of CgIL17-5. The mRNA transcripts of CgIL17-5 were constitutively distributed in all the tested tissues, with the highest level in haemocytes. The mRNA expression level of CgIL17-5 in haemocytes increased significantly at 24 h after Vibrio splendidus stimulation. CgIL17-5 protein was mainly detected in granulocytes which were the main immunocompetent haemocytes in C. gigas. The phosphorylation of mitogen-activated protein kinases (CgJNK, CgERK and CgP38) and nuclear translocation of the transcription factors (CgRel and CgAP-1) in haemocytes were induced after the oysters received an injection of recombinant CgIL17-5 for 2 h. The mRNA expression levels of CgIL-17s, CgTNF-1, Cgdefh1 and Cgdefh2 increased significantly in haemocytes. At the same time, obvious branchial swelling and cilium shedding in gills were observed at 24 h after the oysters received an injection of rCgIL17-5. All the results collectively suggested that CgIL17-5 promoted the activation of CgMAPKs and the nuclear translocation of CgRel and CgAP-1 to promote the mRNA expressions of cytokines and antibacterial peptides.

BCL10 regulates the production of proinflammatory cytokines by activating MAPK-NF-κB/Rel signaling pathway in oysters

B cell lymphoma/leukemia 10 (BCL10) is an important member of the caspase recruitment domain-containing (CARD) protein family, which plays crucial roles in mediating the host inflammatory response. In the present study, a BCL10 homologue was identified from Pacific oyster Crassostrea gigas (designed as CgBCL10). The full length cDNA of CgBCL10 was of 897 bp with an open reading frame of 522 bp encoding a polypeptide of 174 amino acids containing a classical CARD domain. The deduced amino acid sequence of CgBCL10 shared low similarity with the previously identified BCL10s from other species. In the phylogenetic tree, CgBCL10 was firstly clustered with CvBCL10 from Crassostrea virginica and then assigned into the branch of invertebrate BCL10s. The mRNA transcripts of CgBCL10 were highly expressed in gonad, gill, adductor muscle, and haemocytes. After Vibrio splendidus stimulation, the mRNA expression level of CgBCL10 in haemocytes increased significantly (p < 0.01) at 24, 72 and 96 h. In CgBCL10-RNAi oysters, the phosphorylation level of mitogen-activated protein kinases (MAPKs), nuclear translocation of NF-κB/Rel and activator protein-1 (AP-1) in haemocytes were inhibited, and the mRNA expressions of inflammatory cytokines including CgIL17-1, CgIL17-2, CgIL17-3, CgIL17-6 and CgTNF all decreased significantly (p < 0.01) at 12 h after V. splendidus stimulation. These results suggested that CgBCL10 regulated the expression of inflammatory cytokines by activating MAPK kinase, and nuclear translocation of NF-κB/Rel and AP-1 to defense pathogen.

The Regulation of Prototype Foamy Virus 5'Long Terminal Repeats and Internal Promoter by Endogenous Transcription Factors

BACKGROUND

For foamy virus, the transactivator of spumaretrovirus (Tas) could bind directly to target DNA sequences termed as Tas responsive elements and trigger the viral internal promoter (IP) and long terminal repeat (LTR) promoters. The cellular endogenous factors also play an important role in viral gene expressions. We hypothesized that except the viral transcription factor Tas, the cellular endogenous factors also affect the viral gene expression.

METHODS

The full length of the prototype foamy virus (PFV) genome (U21247) was used to predict the potential binding sites of the transcription factors by online software JASPAR (http://jaspar.genereg.net) and Softberry (http://linux1.softberry.com/berry.phtml?topic=index&amp;group=programs&amp;subgroup=promoter). The Dual-Luciferase® Reporter Assay System (Promega, USA) was used to confirm the relative luciferase activities of the test groups. The different representative activating agents or inhibitors of each canonical signal pathway were used to identify the impact of these pathways on PFV 5'LTR and IP promoters.

RESULTS

The results showed different cellular endogenous factors might have respective effects on PFV 5'LTR and IP. It is worth mentioning that activator protein-1 and BCL2-associated athanogene 3, 2 kinds of vital proteins associated with NF-κB and PKC pathways, could activate the basal activity of 5'LTR and IP promoters but inhibit the Tas-regulated activity of both promoters. Furthermore, PFV Tas was identified to trigger the transcription of the NF-κB promoter.

CONCLUSION

NF-κB had a negative effect on PFV 5'LTR and IP promoter activities, the PKC pathway might upregulate 5'LTR and IP promoter activities, and the JNK and NF-AT signal pathway could increase the Tas-regulated promoter activity of PFV 5'LTR. This study sheds light on the interaction between PFV and the host cell and may help utilize the viral promoters in retroviral vectors designed for gene transfer experiments.

Sophoraflavanone M, a prenylated flavonoid from Sophora flavescens Ait., suppresses pro-inflammatory mediators through both NF-κB and JNK/AP-1 signaling pathways in LPS-primed macrophages

(2R)-3α,7,4'-trihydroxy-5-methoxy-8-(γ,γ-dimethylallyl)-flavanone is a prenylated flavonoid isolated from the anti-inflammatory herb Sophora flavescens Ait. We firstly named it sophoraflavanone M (SFM) in accordance with trivial names of related constitutes from this plant. Although various studies investigated the anti-inflammatory properties of prenylated flavonoids from Sophora flavescens Ait., that of SFM remains unclear and is yet to be determined. In the current study, we assessed the anti-inflammatory effects of SFM in LPS-induced in vivo and in vitro models. In the serum of endotoxemia mice, SFM significantly suppressed LPS-elevated inflammatory cytokines. Furthermore, at nontoxic concentrations, SFM reduced LPS-induced production of inflammatory mediators NO, IL-6, TNF-α, and MCP-1 in mouse primary peritoneal macrophages. Accordingly, in LPS-primed RAW264.7 cell line, it also inhibited these mediators' expression at both transcriptional and translational levels without cytotoxicity. Mechanistically, SFM is found to concurrently inhibit two important inflammatory signaling pathways, NF-κB and JNK/AP-1. SFM restrained phosphorylation and degradation of IκBα as well as the subsequent p65 translocation to dampen NF-κB activity. Meanwhile, it also suppressed JNK phosphorylation to inhibit the transcriptional activity of AP-1. These results provide material basis for traditional application of the anti-inflammatory herb Sophora flavescens Ait. and suggest SFM is a promising natural candidate for alleviating inflammatory conditions.

High glucose activates ERK1/2 to stabilize AP1 and increase MMP9 expression in diabetic foot ulcers

Increased matrix metalloproteinase 9 (MMP9) expression is involved in delayed wound healing in diabetic foot ulcers. We created skin wounds in normal SD rats and STZ-induced diabetic SD rats, then we found protein levels of activator protein-1 (AP1), a crucial transcription factor to increase MMP9 transcription, as well as MMP9 was up-regulated in epithelium of diabetic skin tissues. Then, we evaluated the mRNA and protein stability of AP1 subunits C-FOS/C-Jun in HaCaT cells after high glucose treatment. Results showed that high glucose could increase protein stability of C-FOS and C-Jun. Additionally, high glucose also activated extracellular signaling-related kinase 1/2 (ERK1/2). ERK1/2 inhibitor could rescue phosphorylation of C-FOS and C-Jun, increased protein stability of C-Jun, and increased MMP9 expressions. Thus, our study demonstrated that high glucose could activate ERK1/2 to stabilize AP1 and increase MMP9 expression in diabetic skin and HaCaT cells.

AP-1 family transcription factors: a diverse family of proteins that regulate varied cellular activities in classical hodgkin lymphoma and ALK+ ALCL

Classical Hodgkin lymphoma (cHL) and anaplastic lymphoma kinase-positive, anaplastic large cell lymphoma (ALK+ ALCL) are B and T cell lymphomas respectively, which express the tumour necrosis factor receptor superfamily member, CD30. Another feature shared by cHL and ALK+ ALCL is the aberrant expression of multiple members of the activator protein-1 (AP-1) family of transcription factors which includes proteins of the Jun, Fos, ATF, and Maf subfamilies. In this review, we highlight the varied roles these proteins play in the pathobiology of these lymphomas including promoting proliferation, suppressing apoptosis, and evading the host immune response. In addition, we discuss factors contributing to the elevated expression of these transcription factors in cHL and ALK+ ALCL. Finally, we examine therapeutic strategies for these lymphomas that exploit AP-1 transcriptional targets or the signalling pathways they regulate.

Erythromycin reverses cigarette smoke extract-induced corticosteroid insensitivity by inhibition of the JNK/c-Jun pathway

Corticosteroid insensitivity is a feature of airway inflammation in chronic obstructive pulmonary disease (COPD). Erythromycin exhibits anti-inflammatory activity in COPD, but the concrete mechanism is still unclear. This study aimed to investigate the effects of erythromycin on corticosteroid sensitivity in peripheral blood mononuclear cells (PBMCs) and U937 cells (a human monocytic cell line). PBMCs were collected from non-smokers, healthy smoker volunteers, and COPD subjects. U937 cells were incubated with or without erythromycin and stimulated with TNF-α in the presence or absence of cigarette smoke extract (CSE). The dexamethasone (Dex) concentration required to achieve 50% inhibition of TNF-α-induced interleukin (IL)-8 production was determined and the mitogen-activated protein kinase (MAPK)/Activator protein-1 (AP-1) pathway was also evaluated. Erythromycin improved corticosteroid sensitivity in PBMCs obtained from COPD patients and CSE-treated U937 cells. This improvement in corticosteroid sensitivity was associated with reduced c-Jun expression, which resulted from the inhibition of P38 Mitogen-activated protein kinase (P38MAPK), extracellular signal-regulated protein kinase (ERK)1/2, and c-Jun N-terminal kinase (JNK) phosphorylation. Erythromycin had no effects on the phosphorylated and total protein expression levels of P38MAPK and ERK; however, it induced inhibition of the phosphorylated and total protein expression levels of JNK. This study provides evidence that erythromycin restores corticosteroid sensitivity in PBMCs and U937 cells. JNK inhibition by erythromycin restores corticosteroid sensitivity via the inhibition of c-Jun expression. Thus, JNK/c-Jun is a potential novel therapeutic target for COPD.

Virtual screening by 2-D fingerprints, shape and docking for discovering new chemotypes of activator protein-1 inhibitors

Activator protein-1 Fos/Jun proteins bind to cognate DNA and regulate gene expression. Small-molecule inhibitors targeting activator protein-1 DNA binding have been developed in the past decades for therapeutic applications. Recent structural and in silico studies suggest a putative inhibitor binding pocket on the activator protein-1 structure, and computational modeling suggests a consensus binding mode of three classes of known small-molecule inhibitors. Here, virtual screening of two-dimensional fingerprints, shape, and docking was performed in search of novel chemotypes of activator protein-1 inhibitors. A standard score (Z₃-score) coalescing top-ranked ligands from the three methods was used and the top-scoring ligands were clustered by similarity. A representative ligand from each large cluster was evaluated using metadynamics simulations and molecular mechanics calculations. Representative hits showed diverse chemotypes and their modeled binding pose on activator protein-1 reproduced key interactions with binding site residues.Communicated by Ramaswamy H. Sarma.

Fibromodulin is upregulated by oxidative stress through the MAPK/AP-1 pathway to promote pancreatic stellate cell activation

BACKGROUND/OBJECTIVES

Fibromodulin (FMOD) expression in chronic pancreatitis (CP) tissues and its effect on PSC was unknown. Our aim was to investigate the role of FMOD in regulating PSC profibrogenic phenotype and the molecular mechanism of CP.

METHODS

Rat CP models were induced by dibutyltin dichloride. Pancreatic fibrosis was evaluated by Sirius Red staining. The expression of FMOD and α-SMA was measured, the correlation between FMOD expression and fibrosis was investigated in CP models and CP patients. The effects of FMOD on PSCs were examined by CCK-8 and migration assays. We investigated the mechanisms underlying FMOD expression using MND and a MAPK pathway inhibitor. Luciferase reporter and chromatin immunoprecipitation assays were used to investigate the effects of AP-1 on FMOD expression.

RESULTS

Sirius Red staining revealed high collagen deposition in model rats. Higher expression of FMOD and α-SMA was observed in fibrotic tissues, and the expression of FMOD was correlated with that of α-SMA and the areas of Sirius Red staining. Upregulation of FMOD increased the expression of collagen I and α-SMA and the proliferation and migration of PSCs. MND induced FMOD and α-SMA expression, and knockdown of FMOD abated α-SMA expression. ERK and JNK inhibitors attenuated FMOD expression as induced by MND. AP-1 upregulated the expression of FMOD. AP-1 binds to the FMOD promoter and transcriptionally regulates FMOD expression.

CONCLUSION

FMOD levels are upregulated in fibrosis tissues in CP and it is a critical downstream mediator of oxidative stress. FMOD induces PSC activation and maintains the fibrosis phenotype of PSCs.

Benzydamine inhibits osteoclast differentiation and bone resorption via down-regulation of interleukin-1 β expression

Bone diseases such as osteoporosis and periodontitis are induced by excessive osteoclastic activity, which is closely associated with inflammation. Benzydamine (BA) has been used as a cytokine-suppressive or non-steroidal anti-inflammatory drug that inhibits the production of pro-inflammatory cytokines or prostaglandins. However, its role in osteoclast differentiation and function remains unknown. Here, we explored the role of BA in regulating osteoclast differentiation and elucidated the underlying mechanism. BA inhibited osteoclast differentiation and strongly suppressed interleukin-1β (IL-1β) production. BA inhibited osteoclast formation and bone resorption when added to bone marrow-derived macrophages and differentiated osteoclasts, and the inhibitory effect was reversed by IL-1β treatment. The reporter assay and the inhibitor study of IL-1β transcription suggested that BA inhibited nuclear factor-κB and activator protein-1 by regulating IκB kinase, extracellular signal regulated kinase and P38, resulting in the down-regulation of IL-1β expression. BA also promoted osteoblast differentiation. Furthermore, BA protected lipopolysaccharide- and ovariectomy-induced bone loss in mice, suggesting therapeutic potential against inflammation-induced bone diseases and postmenopausal osteoporosis.

AP-1 regulates the expression of IL17-4 and IL17-5 in the pacific oyster Crassostrea gigas

The activator protein-1 (AP-1) plays an important role in inducing the immune effector production in response to cellular stress and bacterial infection. In the present study, an AP-1 was identified from Pacific oyster Crassostrea gigas (designed as CgAP-1) and its function was investigated in response against lipopolysaccharide (LPS) stimulation. CgAP-1 was consisted of 290 amino acids including a Jun domain and a basic region leucine zipper (bZIP) domain. CgAP-1 shared 98.6% similarities with ChAP-1 from oyster C. hongkongensis, and assigned into the branch of invertebrates in the phylogenetic tree. The mRNA transcripts of CgAP-1 gene were detected in all tested tissues with highest expression level in hemocytes, especially in granulocytes. The mRNA expression level of CgAP-1 gene in hemocytes was significantly up-regulated (8.53-fold of that in PBS group, p < 0.01) at 6 h after LPS stimulation. CgAP-1 protein could be translocated into the nucleus of oyster hemocytes after LPS stimulation. The mRNA transcripts of interleukin17s (CgIL17-4 and CgIL17-5) in the hemocytes of CgAP-1-RNAi oysters decreased significantly at 24 h after LPS stimulation, which were 0.37-fold (p < 0.05) and 0.17-fold (p < 0.01) compared with that in EGFP-RNAi oysters, respectively. The results suggested that CgAP-1 played an important role in the immune response of oyster by regulating the expression of CgIL17s.

Evaluation of artesunate for the treatment of adult T-cell leukemia/lymphoma

Adult T-cell leukemia/lymphoma (ATLL) is an aggressive disease caused by infection with human T-cell leukemia virus type 1 (HTLV-1). Successful treatment is limited by resistance to chemotherapies. Therefore, there is an urgent need to develop novel effective strategies. Artesunate (ART), a widely used antimalarial compound, has been shown to exert cytotoxicity. Here, we aimed to assess the anti-ATLL activities of ART and to elucidate the possible molecular mechanisms involved in this effect. Compared with uninfected T cells, HTLV-1-infected T-cell lines were sensitive to ART-induced cytotoxicity. ART caused cell cycle arrest at G₁ and/or G₂/M phases, which was associated with decreased expression of cyclin dependent kinase 1/2/4/6, cyclin B1/D2/E and c-Myc, and increased expression of p21. ART-induced apoptosis corresponded to activation of caspase-8/9/3; decreased expression of Bcl-xL, Bcl-2, myeloid cell leukemia-1, survivin, X-linked inhibitor of apoptosis protein and cellular inhibitor of apoptosis 1/2; and increased expression of Bak. ART increased intracellular reactive oxygen species and activation of the DNA damage marker γ-H2AX. Moreover, ART-induced cytotoxicity was partly reversed by treatment with a reactive oxygen species scavenger, iron chelator, and necroptosis or ferroptosis inhibitor, suggesting the involvement of caspase-dependent and -independent lethal pathways. These effects were correlated with inhibition of nuclear factor-κB and activator protein-1 signaling through dephosphorylation of IκBα, IκB kinase (IKK) α and IKKβ, and decreased expression of JunB and JunD. Importantly, intraperitoneal injection with ART lowered tumor burden in an ATLL murine model. These preclinical results provide a rationale for evaluating the efficacy of ART in patients with ATLL.

The first cloned echinoderm tumor necrosis factor receptor from Holothuria leucospilota: Molecular characterization and functional analysis

In this study, an echinoderm tumor necrosis factor receptor named HLTNFR-16 was first cloned from the tropical sea cucumber Holothuria leucospilota. The full-length cDNA of HLTNFR-16 is 3675 bp in size, containing a 415 bp 5'-untranslated region (UTR), a 2024 bp 3'-UTR and a 1236 bp open reading frame (ORF) encoding a protein of 411 amino acids with a deduced molecular weight of 45.63 kDa. The HLTNFR-16 protein contains a signal peptide, four TNFR domains (the last three were identified as extracellular cysteine-rich domains), a transmembrane region and a death domain. Phylogenetic analysis showed that HLTNFR-16 was clustered into a clade with TNFR-16s in other species, indicating that this echinoderm TNFR may be a new member of the TNFR-16 subfamily. The results of TUNEL assay showed that the over expression of HLTNFR-16 could induce apoptosis in HEK293T cells. When HLTNFR-16 was silenced by siRNA, the apoptosis of sea cucumber coelomocytes induced by inactivated Vibrio harveyi was suppressed significantly, indicating that HLTNFR-16 is important for apoptosis induction. Additionally, luciferase reporter assay exhibited that the over-expressed HLTNFR-16 in HEK293T cells could activate the transcription factors nuclear factor-κB (NF-κB) and activator protein-1 (AP-1). Moreover, the secretion of proinflammatory cytokines interleukin (IL)-1β, IL-6 and IL-18 in HEK293T cells was increased by the over-expression of HLTNFR-16. This study provides evidences for the potential roles of sea cucumber TNFR in the innate immunity.

Liraglutide protects high-glucose-stimulated fibroblasts by activating the CD36-JNK-AP1 pathway to downregulate P4HA1

BACKGROUND

Diabetic cardiomyopathy (DCM) is a serious complication of diabetes mellitus. It's known that glucagon-like peptide-1 (GLP-1) and prolyl 4-hydroxylase subunit alpha-1 (P4HA1) have significant effect on cardiovascular function, but their interaction in cardiac fibroblasts (CFs) is still being unraveled.

METHODS AND RESULTS

The present study demonstrated that glucose promotes CFs proliferation and cardiac fibrosis. Using qRT-PCR, Western blot, CCK-8, EdU, flow cytometry, wound healing and Transwell assays to explore the functions of liraglutide and P4HA1 in high-glucose (HG)-induced CFs, we proved that liraglutide as well as silencing of P4HA1 inhibited cell proliferation, migration and invasion, and promoted cell cycle arrest and apoptosis in HG-induced CFs. In addition, liraglutide downregulated P4HA1 expression, upregulated CD36 and P-JNK expression levels, and enhanced the DNA binding activity of AP-1 on P4HA1. Inhibition of CD36 or p--JNK promoted P4HA1 expression.

CONCLUSIONS

Liraglutide may down-regulate P4HA1 expression at least partly though CD36-JNK-AP1 pathway, thereby reducing myocardial fibrosis. Therefore, our study provides novel insight into the molecular mechanism and function of liraglutide in HG-mediated CFs.

Expression of activator protein-1 in papillary thyroid carcinoma and its clinical significance

Background

The abnormal expression of activator protein-1(AP-1) has recently been investigated in a variety of tumors. While the relationship between AP-1 and thyroid cancer is poorly studied, our study was to evaluate the protein expression and clinical value of AP-1 in papillary thyroid carcinoma (PTC).

Methods

The expression of AP-1 was examined by immunohistochemistry on paraffin-embedded tissues obtained from PTC and correspondent paracancerous tissues of 82 patients.

Results

Compared with paracancerous tissues, AP-1 expression was significantly elevated in PTC tissues and the positive rate was 79.3% (65/82). Our study found a linear trend relationship between the expression of AP-1 and tumor size. However, the differences in AP-1 expression among gender, age, lymph node metastasis, number of lesions, location of the lesion, and extrathyroid invasion are not statistically significant.

Conclusions

The expression of AP-1 plays an important role in the proliferation process of PTC.

Immunolocalization of c-Jun in normal mucosa, oral submucous fibrosis, epithelial dysplasia, and oral squamous cell carcinoma: A comparative study

Background and Objective

c-Jun an activator protein-1 transcription factor component is activated by a variety of extracellular stimuli. Overexpression of c-Jun has been implicated in the pathogenesis of several types of cancer including oral cancer. The aim of this study was to correlate the expression of c-Jun in the normal buccal mucosa (NM), oral submucous fibrosis (OSMF), severe epithelial dysplasia (ED), and well-differentiated squamous cell carcinoma (WDSCC).

Subjects and Methods

Qualitative and quantitative expression of c-Jun was evaluated in a total of 60 histopathologically diagnosed cases, 15 each of NM, OSMF, ED, and WDSCC. The percentage of positive cells (Nuclear labeling index [nLI]) was considered for quantitative assessment and grading of staining for qualitative assessment.

Results

The average nLI of c-Jun expression in NM, OSMF, ED, and WDSCC was 35.02%, 35.61%, 89.09%, and 83.31%, respectively. A statistical significant difference was found in c-Jun expression quantitatively between NM and ED (P = 0.000), NM and WDSCC (P = 0.000), OSMF and ED (P = 0.000), OSMF and WDSCC (P = 0.000), and ED and WDSCC (P = 0.021). Qualitatively, statistical significant difference was seen in an intense c-Jun expression between OSMF and ED (P = 0.000), OSMF and WDSCC (P = 0.032), and ED and WDSCC (P = 0.011).

Conclusion

The overexpression of c-Jun in ED and WDSCC reveals its role in early carcinogenesis as evidenced in this study. Therefore, c-Jun might act in different mechanisms and pathways which lead to a malignant transformation in oral lesions.

Evolutionary and functional analysis of Cyclina sinensis c-Jun AP-1 gene in response to LPS stimulation

The transcription factor activator protein-1 (AP-1) plays an essential and critical role in the regulation of numerous downstream genes involved in various physiological and chemical responses. In this study, we identified a full-length cDNA of the c-Jun AP-1 gene (termed Csc-Jun) from the transcriptome library in Cyclina sinensis. The cDNA contains an 825-bp open reading frame that encodes a 274-amino acid protein sequence, including a characteristic Jun transcription factor domain and a highly conserved basic leucine zipper (bZIP) signature that shares 90% identity to that of Ruditapes philippinarum. Furthermore, a phylogenetic analysis using MrBayes and PhyML software (with Bayesian and maximum likelihood approaches, respectively) revealed that the c-Jun AP-1 family genes might be involved in adapting to various environments in different invertebrates. We implemented the PAML software with the maximum likelihood method to further select and verify the positive selection sites (PSSs) in the Mollusca c-Jun AP-1 genes, and we detected four PSSs located in the Jun transcription factor domain. In addition, a spatial expression analysis showed that the Csc-Jun cDNA transcript was ubiquitously expressed in all of the tested tissues and was strongly expressed in the hepatopancreas and weakly expressed in the tissues of the hemocytes, gill filaments, mantle and adductor muscle. Quantitative real-time PCR showed that the expression profiles of Csc-Jun were significantly upregulated at different times in all of the tested tissues when challenged with lipopolysaccharide (LPS). Furthermore, knockdown of Csc-Jun by RNA interference resulted in a higher mortality of C. sinensis following LPS exposure. Finally, we explored the function of the TLR13-MyD88 signaling pathway in the innate immunity of C. sinensis by RNA interference and immune challenges. The results revealed that the mRNA expression levels of Csc-Jun were all decreased (P < 0.01) in normal and stimulated C. sinensis hemocytes. These data collectively indicated that the c-Jun AP-1 gene might play vital roles in innate immunity and provide new evidence for the evolutionary patterns of innate immune genes in Mollusca.

Anti-inflammatory effect of external use of escin on cutaneous inflammation: possible involvement of glucocorticoids receptor

Escin, as an internally applied anti-inflammatory agent, has been widely used in the treatment of inflammation and edema resulting from trauma or operation in the clinic. However, the effect of its external use on cutaneous inflammation and edema remains unexplored. In the present study, the anti-inflammatory and anti-edematous effects of external use of escin were studied in carrageenan-induced paw edema and histamine-induced capillary permeability in rats, paraxylene-induced ear swelling in mice, and cotton pellet-induced granuloma in rats. Effects of external use of escin gel on prostaglandin E2 (PGE2), tumor necrosis factor-α (TNF-α), and interleukin-1β (IL-1β) were determined by ELISA. The anti-inflammatory mechanism was explored by detecting the expression of glucocorticoid receptor (GR) with Western blotting and Real-time PCR analyses, with further exploration of nuclear factor-κB (NF-κB), p38 mitogen-activated protein kinase (P38MAPK) and activator protein-1 (AP-1) expressions. We demonstrated that external use of escin showed significant anti-inflammatory effects on acute and chronic inflammation in different animal models and its anti-inflammatory effects might be related to down-regulation of PGE2, TNF-α, and IL-1β. The results also showed that escin exerted its anti-inflammatory effects by promoting the expression of GR, with the possible mechanism being inhibition of the expressions of GR-related signaling molecules such as NF-κB and AP-1.

Involvement of the p38 MAPK signaling pathway in overexpression of matrix metalloproteinase-9 during the course of brain edema in 1,2-dichloroethane-intoxicated mice

Accumulated data have revealed that subacute poisoning of 1,2-dichloroethane (1,2-DCE), an industrial solvent used in some countries can cause encephalopathy, in which brain edema is the main pathological change. However, the underlying mechanisms are unclear. In the present study, we hypothesized that the p38 MAPK (p38) signaling pathway could be activated in 1,2-DCE-intoxicated mice, which in turn stimulates transcription factors, such as nuclear factor-κB (NF-κB) and activator protein-1 (AP-1), and then enhances the expression of proinflammatory factors, including matrix metalloproteinase-9 (MMP-9), finally leading to blood-brain barrier (BBB) disruption and brain edema formation. Our results revealed that brain water content and BBB permeability increased significantly in the intoxicated mice. Meanwhile, the levels of phosphorylated p38 (p-p38) and inhibitory κBα (p-IκB), as well as the expression levels of MMP-9, c-jun, c-fos, and p65, also increased markedly in the brains of intoxicated mice. Conversely, the protein levels of ZO-1, occludin and claudin-5 in these mice decreased markedly, but their JAM-1 protein levels increased dramatically. Our results revealed that p-p38 levels in the brains of intoxicated mice were suppressed by pretreatment with a p38 inhibitor. In response to suppressed p-p38 levels, the brain water contents and DNA binding activities of NF-κB and AP-1, as well as the expression levels of MMP-9, c-jun, c-fos, p65, p-IκB and JAM-1, decreased, whereas the protein levels of ZO-1, occludin and claudin-5 increased markedly. Taken together, our findings indicated that the p38 signaling pathway might be activated and involved in the course of brain edema in 1,2-DCE-intoxicated mice.

Nucleic-acid based gene therapy approaches for sepsis

Despite advances in overall medical care, sepsis and its sequelae continue to be an embarrassing clinical entity with an unacceptably high mortality rate. The central reason for high morbidity and high mortality of sepsis and its sequelae is the lack of an effective treatment. Previous clinical trials have largely failed to identify an effective therapeutic target to improve clinical outcomes in sepsis. Thus, the key goal favoring the outcome of septic patients is to devise innovative and evolutionary therapeutic strategies. Gene therapy can be considered as one of the most promising novel therapeutic approaches for nasty disorders. Since a number of transcription factors, such as nuclear factor-κB (NF-κB) and activator protein-1 (AP-1), play a pivotal role in the pathophysiology of sepsis that can be characterized by the induction of multiple genes and their products, sepsis may be regarded as a gene-related disorder and gene therapy may be considered a promising novel therapeutic approach for treatment of sepsis. In this review article, we provide an up-to-date summary of the gene-targeting approaches, which have been developed in animal models of sepsis. Our review sheds light on the molecular basis of sepsis pathology for the development of novel gene therapy approaches and leads to the conclusion that future research efforts may fully take into account gene therapy for the treatment of sepsis.

Fluid shear stress regulates the expression of Lectin-like oxidized low density lipoprotein receptor-1 via KLF2-AP-1 pathway depending on its intensity and pattern in endothelial cells

BACKGROUND AND AIMS

Vascular endothelial cells (ECs) are exposed to fluid shear stress (FSS), which modulates vascular pathophysiology. Lectin-like oxidized low-density lipoprotein receptor-1 (LOX-1) is crucial in endothelial dysfunction and atherosclerosis. We elucidated the mechanism regulating LOX-1 expression in ECs by FSS.

METHODS

Human umbilical vein endothelial cells were exposed to laminar shear stress (LSS) of indicated intensities using a unidirectional steady flow, or to oscillatory shear stress (OSS) using a bidirectional disturbed flow. In vivo studies were performed in a mouse model of partial carotid ligation and human pulmonary artery sections.

RESULTS

Within ECs, OSS upregulated LOX-1 expression, while LSS (20 dyne/cm²) downregulated it. We confirmed that OSS-induced LOX-1 expression was suppressed when the mechanotransduction was inhibited by knockdown of the mechanosensory complex. In addition, we demonstrated that Kruppel-like factor 2 (KLF2) has an inhibitory role on OSS-induced LOX-1 expression. Next, we determined that activator protein-1 (AP-1) was the key transcription factor inducing LOX-1 expression by OSS, which was inhibited by KLF2 overexpression. To explore whether the intensity of LSS affects LOX-1 expression, we tested three different intensities (20, 60, and 120 dyne/cm²) of LSS. We observed higher LOX-1 expression with high shear stresses of 120 dyne/cm² compared to 20 and 60 dyne/cm², with OSS-like KLF2-AP-1 signaling patterns. Furthermore, ECs within disturbed flow regions showed upregulated LOX-1 expression in vivo.

CONCLUSIONS

We concluded that LOX-1 expression on ECs is regulated via FSS depending on its intensity as well as pattern. Furthermore, this is mediated through the KLF2-AP1 pathway of mechanotransduction.

(E)-2-Methoxy-4-(3-(4-methoxyphenyl) prop-1-en-1-yl) phenol attenuates PMA-induced inflammatory responses in human monocytic cells through PKCδ/JNK/AP-1 pathways

(E)-2-Methoxy-4-(3-(4-methoxyphenyl) prop-1-en-1-yl) phenol (MMPP), a new (E)-2,4-bis(p-hydroxyphenyl)-2 - butenal derivative, reportedly has therapeutic effects such as anti-arthritic properties. Although previous studies showed that MMPP has anti-arthritic effects on rheumatoid arthritis (RA), the anti-inflammation mechanism of MMPP remains unclear. In this study, phorbol-12-myristate 13-acetate (PMA) was used as an inflammatory stimulus to evaluate the detailed mechanism of the MMPP-mediated anti-inflammatory effect in human monocytic THP-1 cells. We investigated the effects of MMPP on inflammation-related pathways including protein kinase Cδ (PKCδ), mitogen-activated protein kinase, and activator protein-1 (AP-1). PMA induced the translocation of PKCs from the cytosol to the membrane and phosphorylated JNK. MMPP inhibited PMA-induced membrane translocation of PKCδ, phosphorylation of JNK, and nuclear translocation of AP-1, resulting in downregulation of cyclooxygenase-2 and chemokine ligand 5 production. These findings indicate that MMPP inhibits inflammatory responses in THP-1 cells by mitigating PMA-induced activation of PKCδ and JNK and nuclear translocation of AP-1. Therefore, MMPP may be useful as an anti-inflammatory drug.

Role of the TGFβ/PDCD4/AP-1 Signaling Pathway in Nasopharyngeal Carcinoma and Its Relationship to Prognosis

BACKGROUND

The objective of the present study was to evaluate the role of the TGFβ/PDCD4/AP-1 pathway in nasopharyngeal carcinoma (NPC) and its relationship to NPC prognosis.

METHODS

NPC tissues collected from 66 NPC patients were compared to 17 nasopharyngeal mucosa biopsy specimens collected as normal tissues. Immunohistochemical staining was performed to assess expression of transforming growth factor-β receptor I (TGFβRI), programmed cell death 4 (PDCD4) and activator protein-1 (AP-1). The Kaplan-Meier method was applied to evaluate NPC patient overall survival (OS) and progression-free-survival (PFS). Cox regression analysis was used to estimate independent prognostic factors for NPC. The human NPC cell line CNE2 was selected and treated with SB431542, an inhibitor of TGFβRI; expression of TGFβRI and PDCD4 in CNE2 cells was determined by western blotting. NPC tissues showed higher expression of TGFβRI and AP-1 but lower expression of PDCD4 than normal tissues (all P < 0.05).

RESULTS

The results of Kaplan-Meier analysis showed that TGFβRI-positive patients and AP-1-positive patients had shorter OS and PFS than TGFβRI-negative patients and AP-1-negative patients; additionally, PDCD4-positive patients had higher OS and PFS than PDCD4-negative patients. Cox regression analysis revealed that advanced tumor stage, overexpression of TGFβRI and AP-1, and low expression of PDCD4 were unfavorable factors influencing OS and PFS in NPC patients. Compared with the control group, expression of TGFβRI decreased and that of PDCD4 increased significantly in CNE2 cells treated with the inhibitor (all P < 0.05). These findings indicate that the TGFβ/PDCD4/AP-1 pathway may be associated with NPC development and progression.

CONCLUSION

High expression of TGFβRI and AP-1 and low expression of PDCD4 may be unfavorable prognostic factors for NPC.

Xanthotoxin suppresses LPS-induced expression of iNOS, COX-2, TNF-α, and IL-6 via AP-1, NF-κB, and JAK-STAT inactivation in RAW 264.7 macrophages

Although xanthotoxin has been reported to possess skin-protective and anti-oxidative properties, its anti-inflammatory capacity has not been studied to date. Therefore, we investigated this role as well as the molecular mechanisms of xanthotoxin in lipopolysaccharide (LPS)-induced RAW 264.7 macrophages. Xanthotoxin inhibited production of nitric oxide (NO), prostaglandin E₂ (PGE₂), tumor necrosis factor (TNF-α), and interleukin-6 (IL-6) by the LPS-induced macrophages in a concentration-dependent manner. It also suppressed the LPS-induced inducible nitric oxide synthase (iNOS) and cyclooxygenase-2 (COX-2) expression at the protein levels and iNOS, COX-2, TNF-α, and IL-6 at the mRNA levels. At a molecular level, the effects were related to xanthotoxin-mediated attenuation of the LPS-induced transcriptional and DNA-binding activity of activator protein-1 (AP-1). This attenuation was associated with decreased phosphorylation of c-Fos, but not c-Jun. Xanthotoxin also displayed a suppressive effect on the transcriptional and DNA-binding activity of nuclear transcription factor kappa-B (NF-κB) by inhibiting p65 nuclear translocation. In addition, xanthotoxin significantly reduced the phosphorylation at signal transducers and activators of transcription 1 (STAT1, Ser 727 and Tyr 701) and STAT3 (Tyr 705), as well as Janus kinase (JAK) 1 and 2 in LPS-induced RAW 264.7 macrophages. Finally, xanthotoxin suppressed the LPS-induced phosphorylation of extracellular signal-regulated kinase (ERK) 1/2 and p38 mitogen-activated protein kinase (MAPK). Taken together, these results indicate that xanthotoxin decreases NO, PGE₂, TNF-α, and IL-6 production by downregulation of the NF-κB, AP-1, and JAK/STAT signaling pathways in LPS-induced RAW 264.7 macrophages.

Shizukaol B, an active sesquiterpene from Chloranthus henryi, attenuates LPS-induced inflammatory responses in BV2 microglial cells

The objective of the current study was to evaluate the anti-inflammatory effects of shizukaol B, a lindenane-type dimeric sesquiterpene isolated from the whole plant of Chloranthus henryi, on lipopolysaccharide (LPS)-induced activation of BV2 microglial cells in vitro. Our data showed that shizukaol B concentration-dependently suppressed expression of inducible nitric oxide synthase (iNOS) and cyclooxygenase-2 (COX-2), production of nitric oxide (NO), tumor necrosis factor-α (TNF-α), and interleukin-1β (IL-1β) in LPS-stimulated BV2 microglia. Meanwhile, shizukaol B concentration- and time-dependently inhibited LPS-mediated c-Jun N-terminal kinase 1/2 (JNK) activation, but had little effect on extracellular signal-regulated kinase 1/2 or p38 phosphorylation. Furthermore, shizukaol B significantly blocked LPS-induced activator protein-1 (AP-1) activation, evidenced by reduced phosphorylation and nuclear translocation of c-Jun and DNA binding activity of AP-1. Taken together, our findings suggest that shizukaol B exerts anti-inflammatory effects in LPS-activated microglia partly by modulating JNK-AP-1 signaling pathway.

6'-O-Caffeoyldihydrosyringin isolated from Aster glehni suppresses lipopolysaccharide-induced iNOS, COX-2, TNF-α, IL-1β and IL-6 expression via NF-κB and AP-1 inactivation in RAW 264.7 macrophages

Previously, we found that ethyl acetate extract fraction of Aster glehni exhibited anti-hyperuricemic effects in animal models and also five new caffeoylglucoside derivatives were isolated from this fraction. In this work, we evaluated the anti-inflammatory effects of these caffeoylglucoside derivatives and found that 6'-O-caffeoyldihydrosyringin (2, CDS) most potently inhibited the LPS-induced production of nitric oxide (NO) and prostaglandin E2 (PGE2) in RAW 264.7 macrophages. In addition, CDS was found to concentration-dependently reduce the production of NO, PGE2, and the pro-inflammatory cytokines, such as tumor necrosis factor-α (TNF-α), interleukin-6 (IL-6), interleukin-1β (IL-1β) induced by LPS in macrophages. Consistent with these observations, CDS concentration-dependently inhibited LPS-induced inducible nitric oxide synthase (iNOS) and cyclooxidase-2 (COX-2) expression at the protein level and also iNOS, COX-2, TNF-α, and IL-6, IL-1β expression at the mRNA level. Furthermore, CDS suppressed the LPS-induced transcriptional activities of nuclear factor-κB (NF-κB) and activator protein-1 (AP-1) as well as the phosphorylation of p65 and c-Fos. Taken together, these results suggest that the anti-inflammatory effect of CDS is associated with the downregulation of iNOS, COX-2, TNF-α, IL-1β, and IL-6 expression via the negative regulation of NF-κB and AP-1 activation in LPS-induced RAW 264.7 macrophages.

Pc2-mediated SUMOylation of WWOX is essential for its suppression of DU145 prostate tumorigenesis

Tumor suppressor WW domain-containing oxidoreductase (WWOX) is depleted in various cancer types. Here we report that WWOX is modified by small ubiquitin-like modifier (SUMO) proteins and represses DU145 prostate cancer tumorigenesis in a SUMOylation-dependent manner. Ectopic WWOX was shown to associate with SUMO2/3 or E2 Ubc9. Furthermore, we revealed that WWOX SUMOylation was promoted by E3 ligase polycomb2 (Pc2), and that WWOX associated with Pc2. Meanwhile, anisomycin-induced activator protein-1 (AP-1) activity was markedly diminished by co-expression of SUMO and WWOX. Also, WWOX wild type (WT), but not WWOX SUMO mutant (K176A) markedly reduced both DU145 prostate cancer cell proliferation and xenograft tumorigenesis. Collectively, our findings demonstrate that SUMO modification of WWOX is essential for its suppressive activity for DU145 prostate cancer tumorigenesis.

Endothelin-1 induces connective tissue growth factor expression in human lung fibroblasts by ETAR-dependent JNK/AP-1 pathway

Endothelin-1 (ET-1) acts as a key mediator of vasoconstriction and tissue repair. Overproduction of connective tissue growth factor (CTGF) underlies the development of lung fibrosis. ET-1 induces expression of matrix-associated genes in lung fibroblasts, however, little is known about the signaling pathway of CTGF expression caused by ET-1. In this study, we found that ET-1 caused concentration- and time-dependently increases in CTGF expression in human embryonic lung fibroblast cell line (WI-38). ET-1-induced CTGF expression was inhibited by BQ123 (ETAR antagonist), but not BQ788 (ETBR antagonist). Moreover, ET-1-induced CTGF expression was significantly reduced by JNK inhibitor (SP600125), the dominant-negative mutants of JNK1/2 (JNK1/2 DN), and AP-1 inhibitor (curcumin). ET-1 induced phosphorylations of JNK and c-Jun in time-dependent manners. AP-1 luciferase activity was concentration-dependently increased by ET-1, and this effect was attenuated by SP600125. We also found that ET-1-induced CTGF expression was most controlled by the AP-1 binding region of CTGF promoter. ET-1-indiced CTGF luciferase activity was predominately controlled by the sequence -747 to -408 bp upstream of the transcription start site on the human CTGF promoter. Furthermore, ET-1 caused the formation of AP-1-specific DNA-protein complex and the recruitment of c-Jun to the CTGF promoter. Moreover, we found that ET-1 induced α-smooth muscle actin (α-SMA) expression, which was inhibited by BQ123, SP600125, curcumin, and anti-CTGF antibody. These results suggest that ET-1 stimulates expressions of CTGF and α-SMA through ETAR/JNK/AP-1 signaling pathway, and CTGF is required for ET-1-induced α-SMA expression in human lung fibroblasts.

Glutamine-free condition inhibits lipopolysaccharide-induced invasion of BV2 microglial cells by suppressing of matrix metalloproteinase-9 expression

Studies showing the mechanisms involved in glutamine (Gln) starvation and regulation of matrix metalloproteinase-9 (MMP-9) expression in microglia are rare, even though MMP-9 plays a crucial role in the proinflammatory microenvironment by degrading the blood-brain barrier. We investigated the effects of Gln on the expression of MMP-9 in lipopolysaccharide (LPS)-stimulated BV2 microglial cells. Our findings showed that MMP-9 activity is significantly increased in response to LPS under Gln conditions. However, the Gln-free condition substantially inhibited LPS-induced MMP-9 activity and the expression of its corresponding gene. A matrigel invasion assay demonstrated that the Gln-free condition attenuates LPS-induced invasion of BV2 microglial cells. In addition, our results showed that the Gln-free condition diminishes LPS-induced nuclear factor-kappa B (NF-κB) and activator protein (AP)-1 activity, which are transcription factors that potentially regulate the expression of the MMP-9 gene. Taken together, these data suggest that the Gln-free condition inhibits LPS-induced invasion of BV2 microglial cells by suppressing MMP-9 expression, mainly via inhibition of the NF-κB and AP-1 pathway.

Cilostazol prevents retinal ischemic damage partly via inhibition of tumor necrosis factor-α-induced nuclear factor-kappa B/activator protein-1 signaling pathway

Cilostazol is a specific inhibitor of phosphodiesterase III and is widely used to treat ischemic symptoms of peripheral vascular disease. We evaluated the protective effects of cilostazol in a murine model of ocular ischemic syndrome in which retinal ischemia was induced by 5-h unilateral ligation of both the pterygopalatine artery (PPA) and the external carotid artery (ECA) in anesthetized mice. The effects of cilostazol (30 mg/kg, p.o.) on ischemia/reperfusion (I/R)-induced retinal damage were examined by histological, retinal vascular permeability, and electrophysiological analyses. Using immunoblotting, the protective mechanism for cilostazol was evaluated by examining antiinflammatory effects of cilostazol on the expression of tumor necrosis factors-α (TNF-α) and tight junction proteins (ZO-1 and claudin-5), and the phosphorylations of nuclear factor-kappa B (NF-κB) and c-Jun. The histological analysis revealed that I/R decreased the cell number in the ganglion cell layer (GCL) and the thicknesses of the inner plexiform layer (IPL) and inner nuclear layer (INL), and that cilostazol attenuated these decreases. Additionally, cilostazol prevented the hyperpermeability of blood vessels. Electroretinogram (ERG) measurements revealed that cilostazol prevented the I/R-induced reductions in a-, b-, and oscillatory potential (OP) wave amplitudes seen at 5 days after I/R. Cilostazol inhibited the increased expression of TNF-α and the phosphorylation levels of NF-κB and c-Jun in the retina after I/R. In addition, cilostazol prevented TNF-α-induced reduction of ZO-1 and claudin-5 expression in human retinal microvascular endothelial cells (HRMECs). These findings indicate that cilostazol may prevent I/R-induced retinal damage partly through inhibition of TNF-α-induced NF-κB/AP-1 signaling pathway.

Regulation of the human thioredoxin gene promoter and its key substrates: a study of functional and putative regulatory elements

BACKGROUND

The thioredoxin system maintains redox balance through the action of thioredoxin and thioredoxin reductase. Thioredoxin regulates the activity of various substrates, including those that function to counteract cellular oxidative stress. These include the peroxiredoxins, methionine sulfoxide reductase A and specific transcription factors. Of particular relevance is Redox Factor-1, which in turn activates other redox-regulated transcription factors.

SCOPE OF REVIEW

Experimentally defined transcription factor binding sites in the human thioredoxin and thioredoxin reductase gene promoters together with promoters of the major thioredoxin system substrates involved in regulating cellular redox status are discussed. An in silico approach was used to identify potential putative binding sites for these transcription factors in all of these promoters.

MAJOR CONCLUSIONS

Our analysis reveals that many redox gene promoters contain the same transcription factor binding sites. Several of these transcription factors are in turn redox regulated. The ARE is present in several of these promoters and is bound by Nrf2 during various oxidative stress stimuli to upregulate gene expression. Other transcription factors also bind to these promoters during the same oxidative stress stimuli, with this redundancy supporting the importance of the antioxidant response. Putative transcription factor sites were identified in silico, which in combination with specific regulatory knowledge for that gene promoter may inform future experiments.

GENERAL SIGNIFICANCE

Redox proteins are involved in many cellular signalling pathways and aberrant expression can lead to disease or other pathological conditions. Therefore understanding how their expression is regulated is relevant for developing therapeutic agents that target these pathways.

Activator protein-1 involved in growth inhibition by RASSF1A gene in the human gastric carcinoma cell line SGC7901

AIM: To investigate the role of Ras association domain family protein 1 isoform A (RASSF1A) in gastric tumorigenesis.

METHODS: Through over-expression of RASSF1A gene in the SGC7901 cell line which was induced by a lipofectamine-mediated gene transfer approach. Activator protein-1 (AP-1) DNA binding activity was measured by electrophoretic mobility shift assay (EMSA).

RESULTS: Compared with the control clones, cells over-expressing RASSF1A exhibited significant inhibition of cell growth with G₁ cell cycle arrest in vitro and in vivo. The over-expression of RASSF1A significantly inhibited AP-1 activity in SGC7901 cells (0.981 ± 0.011 vs 0.354 ± 0.053, P < 0.001). In addition, both Western blot analysis and immunocytochemistry demonstrated that RASSF1A down-regulated the expression of c-Fos (0.975 ± 0.02 vs 0.095 ± 0.024, P < 0.001) but not c-Jun.

CONCLUSION: Over-expression of RASSF1A inhibits the growth of SGC7901 cells by negatively regulating the AP-1 activity, the latter in turn negatively signals cell proliferation.