Transcription Factor Activator Protein-1 Research Articles

AP‐1 and Mitf interact with NFATc1 to stimulate cathepsin K promoter activity in osteoclast precursors

Cathepsin K (CTSK) is a secreted protease that plays an essential role in osteoclastic bone resorption and osteoporotic bone loss. We have previously shown that activator protein 1 (AP-1) stimulates CTSK promoter activity and that proximal nuclear factor of activated T cells cytoplasmic 1 (NFATc1)-binding sites play a major role in the stimulation of CTSK gene expression by receptor activator of NFκB ligand (RANKL). In the present study, we have extended these observations and further dissected the effects of transcription factors involved in the regulation of CTSK gene expression. Our aim was to investigate the cooperative interplay among transcription factors AP-1, microphthalmia-associated transcription factor (Mitf), and NFATc1, and the consequent regulatory effects on CTSK transcription. Experiments were carried out in RAW 264.7 cells, which can be readily differentiated to osteoclasts upon RANKL stimulation. Our data show that AP-1, Mitf, and NFATc1 are capable of independently stimulating CTSK promoter activity. A combination of any two factors further enhances CTSK promoter activity, with the combination of AP-1 (c-fos/c-jun) and NFATc1 inducing the largest increase. We further identify a synergistic effect when all three factors cooperate intimately at the proximal promoter region, yielding maximal transcriptional upregulation of the CTSK promoter. RANKL induces temporal localization of AP-1 and NFATc1 to the CTSK promoter. These results suggest that the interaction of multiple transcription factors mediate a maximal response to RANKL-induced CTSK gene expression.

The effect of Helicobacter pylori on the expression of FRA-1 in gastric epithelial cells and its mechanism

Gastric cancer is a major global health threat and is often related with Helicobacter pylori (H. pylori) infection. FRA-1 is a subunit of the activator protein-1 transcription factor complex, which played a central role in cell proliferation and migration. It has also been implicated in stomach inflammation and malignancy. The present study aimed to clarify the relationship between H. pylori infection and production of FRA-1 in controlling cell proliferation and migration and its molecular mechanisms. Cell proliferation was measured by colony formation assay. Cell migration was monitored by transwell migration assay. Gastric mucosal epithelial cells were treated with FRA-1-specific siRNA with or without H. pylori infection in vitro, and RNA and proteins were extracted. The expression of FRA-1 and indicators in cells was determined by RT-PCR and western blot analysis. β-Catenin and TGF-β activities were then assessed by western blotting and immunofluorescence. The expression of FRA-1 increased after H. pylori infection. Additional analysis identified that knockdown of FRA-1 attenuated the H. pylori-induced proliferative activity and migration of gastric cancer cells. Furthermore, upregulation of FRA-1 by H. pylori led to increase in Wnt/β-Catenin levels and TGF-β dependent signaling events. These results demonstrate that the upregulation of FRA-1 in H. pylori-infected gastric epithelial cells plays a key role in the carcinogenic process.

Effects of transcription factor activator protein-2 epsilon methylation on 5-fluorouracil sensitivity in gastric cancer cell lines

Effects of transcription factor activator protein-2 epsilon methylation on 5-fluorouracil sensitivity in gastric cancer cell lines

AP-1 (Activated Protein-1) Transcription Factor JunD Regulates Ischemia/Reperfusion Brain Damage via IL-1β (Interleukin-1β).

Background and Purpose- Inflammation is a major pathogenic component of ischemia/reperfusion brain injury, and as such, interventions aimed at inhibiting inflammatory mediators promise to be effective strategies in stroke therapy. JunD-a member of the AP-1 (activated protein-1) family of transcription factors-was recently shown to regulate inflammation by targeting IL (interleukin)-1β synthesis and macrophage activation. The purpose of the present study was to assess the role of JunD in ischemia/reperfusion-induced brain injury. Methods- WT (wild type) mice randomly treated with either JunD or scramble (control) siRNA were subjected to 45 minutes of transient middle cerebral artery occlusion followed by 24 hours of reperfusion. Stroke size, neurological deficit, plasma/brain cytokines, and oxidative stress determined by 4-hydroxynonenal immunofluorescence staining were evaluated 24 hours after reperfusion. Additionally, the role of IL-1β was investigated by treating JunD siRNA mice with an anti-IL-1β monoclonal antibody on reperfusion. Finally, JunD expression was assessed in peripheral blood monocytes isolated from patients with acute ischemic stroke. Results- In vivo JunD knockdown resulted in increased stroke size, reduced neurological function, and increased systemic inflammation, as confirmed by higher neutrophil count and lymphopenia. Brain tissue IL-1β levels were augmented in JunD siRNA mice as compared with scramble siRNA, whereas no difference was detected in IL-6, TNF-α (tumor necrosis factor-α), and 4-hydroxynonenal levels. The deleterious effects of silencing of JunD were rescued by treating mice with an anti-IL-1β antibody. In addition, JunD expression was decreased in peripheral blood monocytes of patients with acute ischemic stroke at 6 and 24 hours after onset of stroke symptoms compared with sex- and age-matched healthy controls. Conclusions- JunD blunts ischemia/reperfusion-induced brain injury via suppression of IL-1β.

Icariin protects vascular endothelial cells from oxidative stress through inhibiting endoplasmic reticulum stress

ObjectiveTo investigate the protective effect and underlying mechanism(s) of icariin (ICA) in preventing hydrogen peroxide (H2O2)-induced vascular endothelial cell injury via endoplasmic reticulum stress (ERS). MethodsTo study the effects of ICA on H2O2-induced damage, we used the cell counting kit-8 assay to detect cell viability and the terminal deoxynucleotidyl transferase-mediated dUTP nick-end labeling assay to determine cell adhesion and apoptosis, respectively. Spectrophotometry and enzyme-linked immunosorbent assay were used to measure the expression levels of superoxide dismutase (SOD) and glutathione peroxidase (GSH-Px). Subsequently, glucose-regulated protein 78 (GRP78), activating transcription factor-4 (ATF4) and eukaryotic initiation factor-2α (eIF2α) were detected using Western blotting. ResultsIn human umbilical vein endothelial cells, different concentrations of ICA exhibited multiple effects, including reduced H2O2 damage, improved cell viability and adhesion, reduced cell apoptosis and increased SOD and GSH-Px activity. Among the ICA concentrations used, only the H2O2 + 100 μmol/L ICA group had significant differences compared to the H2O2 group. ERS activators H2O2 and dl-dithiothreitol (DTT) significantly increased GRP78, ATF4 and eIF2α expressions, decreased cell activity and reduced SOD and GSH-Px activity. In contrast, the H2O2 + 100 μmol/L ICA and H2O2 + 100 μmol/L ICA + DTT groups had significant inhibitory effects on the expressions of GRP78, ATF4 and eIF2α proteins, showing enhanced cell viability and SOD and GSH-Px activity. ConclusionThe results showed the dose-dependent effects of ICA against H2O2-induced injury in vascular endothelial cells. The inhibition of GRP78, ATF4 and eIF2α protein expressions in the ERS, and the subsequent alleviation of oxidative stress damage, might be the molecular mechanism.

Glutathione peroxidase-1 inhibits transcription of regenerating islet-derived protein-2 in pancreatic islets

Our group previously demonstrated that overexpression of selenium-dependent glutathione peroxidase-1 (GPX1) in mice (OE) led to escalated glucose-stimulated insulin secretion and hyperinsulinemia. Because we found a strong correlation of this phenotype with a diminished expression of regenerating islet-derived protein 2 (REG2) in the OE pancreatic islets, the present study was to reveal underlying mechanisms for that down-regulation of REG2 by GPX1 as a major scavenger of reactive oxygen species. We first treated the OE and wild-type (WT) mice and their islets with ROS-generating diquat, streptozotocin, and H2O2 and ROS-scavenging ebselen and N-acetylcysteine (NAC). Their effects on pancreatic and islet REG2 protein and(or) secretion were opposite (P < 0.05). Thereafter, we identified 13 transcriptional factors with putative binding sites in the Reg2 proximate promoter, and found that only activator protein-1 (AP-1) and albumin D box-binding protein (DBP) mRNA and protein levels were affected (elevated) (P < 0.05) by the GPX1 overproduction in the OE pancreatic islets compared with the WT islets. Contrary to that of Reg2 expression, their mRNA abundances in the cultured islets were elevated (P < 0.05) by ebselen and NAC, but decreased (P < 0.05) by H2O2. Both AP-1 and DBP could bind to the Reg2 promoter at the location of −168 to 0 base pair (bp) in the OE islets. Deleting the AP-1 (−143/-137 and −60/-57 bp) and(or) DBP (−35/-29 bp) binding domains in the Reg2 promoter attenuated and(or) abolished the inhibition of Reg2 promoter activation by ebselen as the GPX1 mimic in βTC-3 cells. In conclusion, the down-regulation of Reg2 expression in the GPX1-overproducing pancreatic islets was mediated by a transcriptional inhibition of the gene through two ROS responsive transcription factors AP-1 and DBP. Our findings reveal GPX1 as a novel regulator of Reg2 expression, and linking these two previously-unrelated proteins will have broad biomedical implications.

Wingless modulates activator protein-1-mediated tumor invasion.

Metastasis begins with a subset of local tumor cells acquiring the potential to invade into surrounding tissues, and remains to be a major obstacle for cancer treatments. More than 90% of cancer patients died from tumor metastasis, instead of primary tumor growth. The canonical Wnt/β-catenin pathway plays essential roles in promoting tumor formation, yet its function in regulating tumor metastasis and the underlying mechanisms remain controversial. Here we employed well-established Drosophila tumor models to investigate the regulating mechanism of Wingless (Wg) pathway in tumor invasion. Our results showed that Wg signaling is necessary and sufficient for cell polarity disruption-induced cell migration and molecular changes reminiscent of epithelial-mesenchymal transition (EMT). Moreover, reducing Wg signaling suppressed lgl-/-/RasV12-induced tumor invasion, and cooperation between Arm and RasV12 is sufficient to induce tumor invasion. Mechanistically, we found that cell polarity disruption activates JNK signaling, which in turn upregulate wg expression through transcription factor activator protein-1 (AP-1). We identified a consensus AP-1 binding site located in the 2nd intron of wg, and confirmed that it is essential for AP-1 induced wg transcription both in vitro and in vivo. Lastly, we confirmed that the transcriptional activation of WNT by AP-1 is conserved in human cancer cells. These evidences reveal a positive role of Wnt/β-catenin pathway in tumor invasion, and provide a conserved mechanism that connects JNK and Wnt signaling in regulating tumor progression.

Shear stress regulates eNOS signaling in human umbilical vein endothelial cells via SRB1-PI3KAP1 pathway

Background: The occurrence and development of atherosclerosis are closely related to shear stress on the endothelial cells. However, related molecular mechanisms of controlling mechanical signal transduction in endothelial cells remain largely unknown. Aim of the Study: To obtain this goal, here, a parallel-plate flow chamber was used to impose laminar shear stress (8.4 dyne/cm2 ) on endothelial cells for 0 minute (min), 10 min, 30 min, 60 min, and 120 min. Subjects and Methods: The RNA interference was employed to down-regulate scavenger receptor class B1 (SRB1) and LY294002 was performed to block the phosphorylation status of the phosphoinositide 3-kinase pathway. Then, the cell status was observed under the microscope, followed by detection of phosphorylated phosphoinositide 3-kinase (PI3K), p38, extracellular signal-regulated protein kinases 1 and 2 and the binding activities of activator protein 1, nuclear factorκB and endothelial nitric oxide synthase (eNOs) by western blot. The results showed that shear stress (8.4 dyne/cm2 ) for 60 min induced obvious cell morphologic changes. Meanwhile, PI3K phosphorylation and eNOS expression were significantly increased by shear stress while reversed by SRB1 si-RNA and LY294002. Additionally, shear stress caused the enhanced binding activity of nuclear transcription factor activator protein 1 (AP-1) to DNA from 10 to 120 min, while only at 30 and 60 min for NF-κB. After treatment with SRB1 si-RNA and LY294002 inhibitor, the binding activities of AP-1 and DNA was significantly decreased, however, there was no effect on NF-κB binding activity. Results: Therefore, SRB1 plays a crucial role in mediating shear stress-induced eNOS activation in endothelial cells via PI3K-AP1 pathway. These findings will provide an important understanding of shear stress-induced cell alterations in clinic detection

Eukaryotic Initiation Factor 5B (eIF5B) Cooperates with eIF1A and eIF5 to Facilitate uORF2-Mediated Repression of ATF4 Translation.

A variety of cellular stresses lead to global translation attenuation due to phosphorylation of the alpha subunit of eukaryotic initiation factor 2 (eIF2), which decreases the availability of the eIF2-GTP-Met-tRNAi ternary complex. However, a subset of mRNAs continues to be translated by non-canonical mechanisms under these conditions. In fact, although translation initiation of activating transcription factor 4 (ATF4) is normally repressed by an upstream open reading frame (uORF), a decreased availability of ternary complex leads to increased translation of the main ATF4-coding ORF. We show here that siRNA-mediated depletion of eIF5B—which can substitute for eIF2 in delivering Met-tRNAi—leads to increased levels of ATF4 protein in mammalian cells. This de-repression is not due to phosphorylation of eIF2α under conditions of eIF5B depletion. Although eIF5B depletion leads to a modest increase in the steady-state levels of ATF4 mRNA, we show by polysome profiling that the depletion of eIF5B enhances ATF4 expression primarily at the level of translation. Moreover, eIF5B silencing increases the expression of an ATF4-luciferase translational reporter by a mechanism requiring the repressive uORF2. Further experiments suggest that eIF5B cooperates with eIF1A and eIF5, but not eIF2A, to facilitate the uORF2-mediated repression of ATF4 translation.

Interplay of transcription factors STAT3, STAT1 and AP-1 mediates activity of the matrix metallo-proteinase-1 promoter in colorectal carcinoma cells.

Signal Transducers (STATs) 1 and 3 and Activator Protein 1 (AP-1) are transcription factors involved in the development of malignancy in colorectal carcinoma (CRC). Matrix Metalloproteinase 1 (MMP-1) is a protease frequently dysregulated in de-differentiated and invasive cancer cells. Its expression is influenced by STAT and AP-1 transcription factors. We studied their contributions to transcriptional regulation of MMP-1 in colorectal carcinoma (CRC) cells. Both STAT3 and AP-1 contribute individual expression-inducing and additive effects and interact with the MMP-1 promoter. DNA binding of AP-1 protein c-Jun is stimulation-independent but modulated by STAT3 and a STAT recognition DNA element. Activated STAT3 showed a suppressive effect on AP-1-mediated MMP-1 mRNA upregulation as shown by STAT3 knockdown. Surprisingly, activated STAT1 overcame STAT3-dependent repression of AP-1-driven MMP-1 expression. Moreover, combined STAT3, STAT1 and AP-1 activities evoked maximal MMP-1 mRNA levels in a synergistic manner. Our results suggest a dominant role of AP-1 in transcriptional upregulation of MMP-1 in CRC cells which is modulated by joint functions of STAT3 and STAT1. The individual and combinatorial activity of these factors is of diagnostic and prognostic interest.

Forskolin and Phorbol 12-myristate 13-acetate modulates the expression pattern of AP-1 factors and cell cycle regulators in estrogen-responsive MCF-7 cells

Activator protein-1 (AP-1) transcription factor is a key component of many signal transduction pathways involved in the regulation of cellular processes and controls rapid responses of mammalian cells when exposed to the variety of stimulus. The phorbol 12-myristate 13-acetate and Forskolin (Fo) are well-known kinase activators/stimulators of Protein Kinase C (PKC) and Protein Kinase A (PKA) respectively. Importantly, these kinases are found to be present in transitional points of many cell signaling pathways, especially those involved in proliferation. The stimulating effect of PKC and PKA on the expression of AP-1 factors in MCF-7 breast cell proliferation is not well characterized. Hence, the role of PKC by PMA treatment and the role of PKA by using Fo in MCF-7 cells is investigated. Where, cells treated with PMA showed increased cell proliferation, while Fo had no effect, but inhibited the PMA induced proliferation. The RT-PCR results showed the PMA induced c-Jun, c-Fos and Fra-1 expressions compared to control and Fo. However, Fo in combination with PMA, inhibit the PMA induced above mRNA expressions where Fo alone has no effect. Western blot studies validated the c-Jun expressions in PMA treated MCF-7 cells. Further, PMA increases the mRNA expression of Cyclin-E1, Cyclin-D1, and CDK-4, whereas Fo decreases their expressions. Thus, mitogenic effect of PMA and inhibitory action of Fo on MCF-7 cells is probably enhanced via activation of AP-1 factors and concomitant action of cell cycle regulators in the downstream singling cascade.

Sulfated polysaccharide JCS1S2 inhibits angiogenesis via targeting VEGFR2/VEGF and blocking VEGFR2/Erk/VEGF signaling

More and more evidences suggested that sulfated natural glycans had impact on angiogenesis. However, the molecular targets and functional mechanism of glycans are still vague. JCS1S2 was the sulfated mannoglucan featured with a backbone of 1, 4-linked β-Manp and 1, 4-linked α-Glcp with sulfation at C-6 of β-Manp and α-Glcp residues, respectively. The degree of substitution of this sulfated polysaccharide was 1.74 and its molecular weight was 56.2 kDa. We provided evidences that JCS1S2 could disrupt angiogenesis both in vitro and in vivo. This sulfated polysaccharide inhibited migration and tube formation of human microvascular endothelial cells (HMEC-1) whereas showed no effect on the cells proliferation. Further study uncovered that JCS1S2 bound to both VEGF (vascular endothelial growth factor) (KD value: 4.82 × 10−9) and VEGFR2 (Vascular Endothelial Growth Factor Receptor 2) (KD value: 1.50 × 10-7) to inactivate VEGFR2 phosphorylation. In addition, JCS1S2 blocked downstream signaling and impaired the expression of VEGF and its transcription factor AP-1 (Activator protein-1). These results demonstrated that JCS1S2 interrupted angiogenesis via blocking VEGF signaling transduction and could be a potential anti-angiogenetic agent for disease treatment.

Tomatidine, a novel antiviral compound towards dengue virus

Dengue is the most common arboviral disease worldwide with 96 million symptomatic cases annually. Despite its major impact on global human health and huge economic burden there is no antiviral drug available to treat the disease. The first tetravalent dengue virus vaccine was licensed in 2015 for individuals aged 9 to 45, however, most cases are reported in infants and young children. This, together with the limited efficacy of the vaccine to dengue virus (DENV) serotype 2, stresses the need to continue the search for compounds with antiviral activity to DENV. In this report, we describe tomatidine as a novel compound with potent antiviral properties towards all DENV serotypes and the related Zika virus. The strongest effect was observed for DENV-2 with an EC50 and EC90 value of 0.82 and 1.61 μM, respectively, following infection of Huh7 cells at multiplicity of infection of 1. The selectivity index is 97.7. Time-of-drug-addition experiments revealed that tomatidine inhibits virus particle production when added pre, during and up to 12 h post-infection. Subsequent experiments show that tomatidine predominantly acts at a step after virus-cell binding and membrane fusion but prior to the secretion of progeny virions. Tomatidine was found to control the expression of the cellular protein activating transcription factor 4 (ATF4), yet, this protein is not solely responsible for the observed antiviral effect. Here, we propose tomatidine as a candidate for the treatment of dengue given its potent antiviral activity.

Protective Effects of Euphrasia officinalis Extract against Ultraviolet B-Induced Photoaging in Normal Human Dermal Fibroblasts

Ultraviolet (UV) radiation induces skin photoaging, which is associated with the elevation of matrix metalloproteinases (MMPs) and the impairment of collagen. The Euphrasia species play a well-known role in the treatment of certain eye disorders through their anti-oxidative and anti-inflammatory activities. However, their protective activity toward UVB-induced damage remains unclear. In the present study, we investigated the protective effect of Euphrasia officinalis (95% ethanol extract) on UVB-irradiated photoaging in normal human dermal fibroblasts (NHDFs). Our results show that Euphrasia officinalis extract exhibited obvious reactive oxygen species (ROS) and 2,2′-azino-bis (3-ethylbenzothiazoline-6-sulfonic acid) (ABTS) radical scavenging activity, enhanced NHDF cell migration, and reduced UVB-induced apoptosis. The UVB-induced increases in MMP-1 and MMP-3 and decrease in type I procollagen were ameliorated by Euphrasia officinalis treatment, which worked by suppressing the mitogen-activated protein kinase (MAPK) and nuclear transcription factor activator protein 1 (AP-1) signaling pathways. Taken together, our data strongly suggest that Euphrasia officinalis ethanol extract could reduce UVB-induced photoaging by alleviating oxidative stress, proinflammatory activity, and cell apoptosis.

Reduction of Transplant Vasculopathy by Intraoperative Nucleic Acid-based Therapy in a Mouse Aortic Allograft Model.

Transplant vasculopathy (TV) is the main limiting factor for long-term graft survival characterized by fibrosis, myofibroblast, and smooth muscle cell (SMC) proliferation. Decoy oligodeoxynucleotide (dODN) against the transcription factor activator protein-1 (AP-1) might interfere with the expression of AV-related genes that govern neointima formation. Aortic allografts from DBA/2 mice were incubated with control buffer, consensus, or mutated control AP-1 dODN and were transplanted into the infrarenal aorta of C57BL/6 mice. Cyclosporine A (10 mg/kg body weight [BW]) was administered daily. Explantation and histomorphometric and immunohistochemical evaluation was performed after 30 days. Matrix metalloproteinase (MMP) activity was visualized by gelatin in situ zymography. Intima-to-media (I/M) ratio and neointima formation were significantly reduced in the consensus AP-1 dODN treatment group by 37% (p < 0.05) and 67% (p < 0.01), respectively. SMC α-actin-2 staining and macrophage marker expression revealed a marked reduction in the neointima. I/M ratio was found to correlate with the number of tissue macrophages (p < 0.05). MMP and fibrosis marker expression were not significantly altered. Intraoperative AP-1dODN utilization might be a strategy to preserve graft function after transplantation.

Leptin upregulates smooth muscle cell expression of MMP-9 to promote plaque destabilization by activating AP-1 via the leptin receptor/MAPK/ERK signaling pathways.

Leptin has been reported to be expressed in carotid atherosclerotic plaques, where it can promote lesion instability. Matrix metalloproteinases (MMPs) produced by smooth muscle cells (SMCs) are known to contribute to the weakening of atherosclerotic plaques via the degradation of extracellular matrix (ECM) proteins. The present study investigated whether leptin promotes plaque rupture by increasing the expression of MMP in SMCs in vivo and in vitro. In vivo, the neointima/media ratio and expression of MMP in the carotid artery of ob/ob mice were measured following carotid ligation and systemic administration of leptin. In vitro, the effect of leptin treatment on the expression of MMP in isolated SMCs and the underlying signaling pathways were investigated by gelatin zymography and western blot analysis. The results demonstrated that leptin treatment significantly increased the neointima/media ratio and expression of MMP-9 in the carotid artery of mice following carotid ligation. In vitro, leptin also significantly increased the expression and activity of MMP-9 in cultured SMCs in a dose-dependent manner. Leptin also increased the production of MMP-9 by activating leptin receptor and mitogen-activated protein kinases, including extracellular signal-regulated kinase (ERK) and c-Jun N-terminal kinase (JNK), which in turn enhanced the binding of the transcription factor activator protein-1 (AP-1) to the MMP-9 promoter. The inhibition of leptin-activated phosphorylation of ERK and JNK suppressed the leptin-stimulated expression of AP-1 and MMP-9. Leptin treatment induced the expression of MMP-9 in SMCs, suggesting that leptin may have substantial involvement in plaque rupture by promoting the degradation of ECM.

Cloning and expression of a transcription factor activator protein-1 member identified from the swimming crab Portunus trituberculatus.

Transcription activator proteins are regulatory proteins that bind to the promoter regions of target genes. Transcription activator protein-1 (AP-1) regulates numerous genes related to the immune system, apoptosis, and proliferation. In this study, the full-length cDNA of AP-1 from Portunus trituberculatus (PtAP-1) was identified by expressed sequence tag analysis and cDNA-end rapid amplification. The gene is 1183bp and encodes a 256-amino acid protein with a predicted molecular mass and isoelectric point of 28.96kDa and 8.90, respectively. PtAP-1 showed the highest expression level in the gonad tissue and the lowest expression level in blood, hemocyte, muscle, hepatopancreas, and gill, during the first 6h of low-salinity stimulation (10%). Additionally, we observed steady decreases in PtAP-1 mRNA expression in the gill, but at 12h, expression was initially upregulated, followed by a significant decrease until restoration to baseline levels at 48h. Additionally, Vibrio alginolyticus challenge resulted in significant upregulation of PtAP-1 expression in the first 6h, which was maintained at high levels for 48h. From 48 to 72h, we observed decreases in PtAP-1 levels, although they remained significantly higher than those detected at baseline. These results suggested that PtAP-1 is involved in the immune response and osmoregulation of crustaceans.

Molecular characterization and functional analysis of MyD88 from the tropical sea cucumber, Holothuria leucospilota

In this study, a myeloid differentiation factor 88 (MyD88) named as HLMyD88 was identified from the sea cucumber Holothuria leucospilota. The full-length cDNA of HLMyD88 is 4797 bp in size, containing a 227 bp 5′-untranslated region (UTR), a 3721 bp 3′-UTR and an 849 bp open reading frame (ORF) encoding a protein of 282 amino acids with a deduced molecular weight of 32.25 kDa HLMyD88 contains an N-terminal death domain and a C-terminal Toll/interluekin-1 receptor (TIR) domain with three highly conserved sequence motifs named as Box 1, Box 2 and Box 3. The results of luciferase reporter assay showed that over-expressed HLMyD88 in HEK293T cells could activate the transcription factors nuclear factor-κB (NF-κB) and activator protein 1 (AP-1). Additionally, the secretion of proinflammatory cytokines IL-1β and TNF-α in the HEK293T cells was increased by over-expressed HLMyD88, indicating the potential role of HLMyD88 in the innate immunity of sea cucumber. Moreover, we further confirmed that over-expressed HLMyD88 could also induce apoptosis.

Inhibitory Effect of Opuntia humifusa Fruit Water Extract on Solar Ultraviolet-Induced MMP-1 Expression.

Opuntia humifusa is a type of cactus whose fruits have been used in folk medicine for the treatment of several diseases. In the present study, we aimed to determine whether O. humifusa fruit water extract (OHE) has inhibitory effects against solar ultraviolet (sUV)-induced matrix metalloproteinase-1 (MMP-1) expression. In ex vivo human skin, we found that OHE suppressed sUV radiation-induced MMP-1 expression. The inhibitory effect of OHE was confirmed in human dermal fibroblasts. OHE treatment reduced sUV-induced MMP-1 expression by suppressing reactive oxygen species (ROS) generation and phosphorylation of c-Jun, a component of transcription factor activator protein 1 (AP-1). On the other hand, OHE recovered the tissue inhibitor of matrix metalloproteinase 1 (TIMP-1) and type 1 collagen production attenuated by sUV. As upstream signaling pathways for AP-1, MKK4-JNK, MEK-ERK, and MKK3/6-p38 phosphorylation were downregulated by OHE treatment. In addition, OHE exhibited DPPH radical scavenging activity. These findings demonstrate that OHE has a preventive effect against sUV-induced skin damage via suppression of pathways triggered by ROS.

Glucocorticoid-Induced Leucine Zipper Inhibits Interferon-Gamma Production in B Cells and Suppresses Colitis in Mice.

Glucocorticoid-induced leucine zipper (GILZ) is transcriptionally upregulated by glucocorticoids (GCs) and mediates many of the anti-inflammatory effects of GCs. Since B cell activity has been linked to cytokine production and modulation of inflammatory responses, we herein investigated the role of GILZ in B cells during colitis development. B cell-specific gilz knock-out (gilz B cKO) mice exhibited increased production of the pro-inflammatory cytokine IFN-γ in B cells, and consequently CD4+ T cell activation. Increased IFN-γ production in B cells was associated with enhanced transcriptional activity of the transcription factor activator protein-1 (AP-1) on the IFN-γ promoter. Moreover, GILZ deficiency in B cells was linked to enhanced susceptibility to experimental colitis in mice, and this was reversed by administering GILZ protein. Interestingly, we observed increased production of IFN-γ in both B and T cells infiltrating the lamina propria (LP) of gilz B cKO mice. Together, these findings indicate that GILZ controls IFN-γ production in B cells, which also affects T cell activity, and increased production of IFN-γ by B and T cells in LP is associated with predisposition to inflammatory colitis in mice.