The screening and expression of polysaccharide deacetylase from Caulobacter crescentus and its function analysis.

The bacterium Caulobacter crescentus secretes an adhesive polysaccharide called holdfast, which is the known strongest underwater adhesive in nature. The deacetylase encoded by hfs (holdfast synthesis) H gene is a key factor affecting the adhesion of holdfast. Its structure and function are not yet clear, and whether other polysaccharide deacetylases exist in C. crescentus is still unknown. The screening of both HfsH and its structural analogue as well as their purification from the artificial expression products of Escherichia coli is the first step to clarify these questions. Here, we determined the conserved domains of HfsH via sequence alignment among carbohydrate esterase family 4 enzymes and screened out its structural analogue (CC_2574) in C. crescentus. The recombinant HfsH and CC_2574 were effectively expressed in E. coli. Both of them were purified by chromatography from their corresponding productions in E. coli and were then functionally analyzed. The results indicated that a high deacetylase activity (61.8 U/mg) was observed in recombinant HfsH but not in CC_2574, which suggesting that HfsH might be the irreplaceable gene mediating adhesion of holdfast in C. crescentus. Moreover, the divalent metal ions Zn2+ , Mg2+ , and Mn2+ could promote the activity of recombinant HfsH at the concentration from 0.05 to 1 mM, but inhibit its activity when the concentration exceeds 1 mM. In sum, our study first realized the artificial production of polysaccharide deacetylase HfsH and its structural analogue, and further explored their functions, both of which laid the foundation for the development of new adhesive materials.

TRIM24 promotes stemness and invasiveness of glioblastoma cells via activating Sox2 expression.

BACKGROUND: Glioblastoma stem cells (GSCs) are a subpopulation of glioblastoma (GBM) cells that are critical for tumor invasion and treatment resistance. However, little is known about the function and mechanism of tripartite motif-containing 24 (TRIM24) in GSCs. METHODS: Immunofluorescence, flow cytometry, and western blot analyses were used to evaluate TRIM24 and cluster of differentiation (CD)133 expression profiles in GBM surgical specimens and GSC tumorspheres. Different TRIM24 expression levels in patients' tumors, as measured by both immunohistochemistry and western blot, were related to their corresponding MRI data. Wound healing, Matrigel invasion, and xenograft immunohistochemistry were conducted to determine GBM cell invasion. RESULTS: We identified that TRIM24 was coexpressed with CD133 and Nestin in GBM tissues and tumorsphere cells. Limiting dilution assays and xenotransplantation experiments illustrated that knockdown of TRIM24 expression reduced GSC self-renewal capacity and invasive growth. TRIM24 expression levels were positively associated with the volumes of peritumoral T2 weighted image abnormality. Rescue experiments indicated TRIM24 participation in GBM infiltrative dissemination. Chromatin immunoprecipitation, reporter gene assay, PCR, western blot, and immunohistochemistry demonstrated that TRIM24 activated the expression of the pluripotency transcription factor sex determining region Y-box 2 (Sox2) to regulate GBM stemness and invasion in vitro and in vivo. Finally, the close relationship between TRIM24 and Sox2 was validated by testing samples enrolled in our study and exploring external databases. CONCLUSIONS: Our findings uncover essential roles of the TRIM24-Sox2 axis in GBM stemness and invasiveness, suggesting TRIM24 as a potential target for effective GBM management.

PM2.5 exposure induces vascular dysfunction via NO generated by iNOS in lung of ApoE-/- mouse.

PM2.5 exposure exacerbates cardiovascular diseases via oxidative stress and inflammation, the detailed mechanism of which is unclear. In this study, the effects of oxidative stress and inflammation, as well as vascular structure and function were studied by multiple PM2.5 exposure model of ApoE-/- mice. The results indicated that NO produced by iNOS not cNOS might play important roles in inducing vascular dysfunction after PM2.5 exposure. The occurrence order and causality among NO, other oxidative stress indicators and inflammation is explored by single PM2.5 exposure. The results showed that NO generated by iNOS occurred earlier than that of other oxidative stress indicators, which was followed by the increased inflammation. Inhibition of NOS could effectively block the raise of NO, oxidative stress and inflammation after PM2.5 exposure. All in all, we firstly confirmed that NO was the initiation factor of PM2.5 exposure-induced oxidative stress, which led to inflammation and the following vascular dysfunction.

PM2.5 aggravates diabetes via the systemically activated IL-6-mediated STAT3/SOCS3 pathway in rats' liver.

PM2.5 exposure aggravates type 2 diabetes, in which inflammatory factors play an important role. In this study, we aimed to explore the mechanisms responsible for aggravating diabetes after PM2.5 exposure, and study the roles of inflammatory factors in insulin-resistant type 2 diabetes. Our study indicated that short-time PM2.5 exposure enhances insulin resistance in type 2 diabetic rats and significantly raises inflammatory factors, including IL-6, TNF-α, and MCP-1, in lungs. However, we found that of these inflammatory factors only IL-6 levels are elevated in blood, liver, adipose tissue, and macrophages, but not in skeletal muscle. IL-6 induced activation of the STAT3/SOCS3 pathway in liver, but not other downstream pathways including STAT1, ERK1/2, and PI3K. Both STAT3 inhibition and IL-6 neutralization effectively alleviated the disorders of glucose metabolism after PM2.5 exposure. Taken together, this suggests that the systemic increase in IL-6 may play an important role in the deterioration of the type 2 diabetes via IL-6/STAT3/SOCS3 pathway in liver after short-time exposure to PM2.5. Besides, we unexpectedly found a stronger resistance to the PM2.5 exposure-induced increase in IL-6 in skeleton muscle than those of many other tissues.

The Combination of Adipose-derived Schwann-like Cells and Acellular Nerve Allografts Promotes Sciatic Nerve Regeneration and Repair through the JAK2/STAT3 Signaling Pathway in Rats.

Schwann cells (SCs) combined with acellular nerve allografts (ANAs) effectively promote the regeneration and repair of peripheral nerves, but the exact mechanism has not been fully elucidated. However, the disadvantages of SCs include their limited source and slow rate of expansion in vitro. Previous studies have found that adipose-derived stem cells have the ability to differentiate into Schwann-like cells. Therefore, we speculated that Schwann-like cells combined with ANAs could profoundly facilitate nerve regeneration and repair. The aim of the present study was to investigate the cellular and molecular mechanisms of regeneration and repair. In this study, tissue-engineered nerves were first constructed by adipose-derived Schwann-like cells and ANAs to bridge missing sciatic nerves. Then, the rats were randomly divided into five groups (n = 12 per group): a Control group; a Model group; an ADSC group; an SC-L group; and a DMEM group. Twelve weeks postsurgery, behavioral function tests and molecular biological techniques were used to evaluate the function of regenerated nerves and the relevant molecular mechanisms after sciatic nerve injury (SNI). The results showed that adipose-derived Schwann-like cells combined with ANAs markedly promoted sciatic nerve regeneration and repair. These findings also demonstrated that the expression of neurotrophic factors (NFs) was increased, and the expression of Janus activated kinase2 (JAK2)/P-JAK2, signal transducer and activator of transcription-3 (STAT3)/P-STAT3 was decreased in the spinal cord after SNI. Therefore, these results suggested that highly expressed NFs in the spinal cord could promote nerve regeneration and repair by inhibiting activation of the JAK2/STAT3 signaling pathway.

The protective role of IL-1Ra on intestinal ischemia reperfusion injury by anti-oxidative stress via Nrf2/HO-1 pathway in rat.

BACKGROUND: Intestinal ischemia reperfusion injury is a frequent clinical damage, in which the oxidative stress and inflammation play an important role. Interleukin-1 receptor antagonist (IL-1Ra) is a natural anti-inflammatory factor, however, its effect on intestinal ischemia reperfusion injury remains unclear. METHODS: The rat model of intestinal I/R was induced by occlusion (for 60 min) and reopening (for 60 min) of superior mesenteric artery. The rats were randomly divided into the following 5 groups: sham-operation(S), model (I/R),10 mg/kgIL-1Ra + I/R (C1),20 mg/kgIL-1Ra + I/R (C2), and30 mg/kgIL-1Ra + I/R (C3). RESULTS: In this study it was the first time to confirm that IL-1Ra had a significant protection against the intestinal ischemia reperfusion injury. IL-1Ra not only effectively inhibited the expression of inflammatory factors (such as IL-1ß, IL-6 and TNF-α) and the activation of neutrophil in intestinal tissues, but also decreased the death of intestinal cells and the damages of intestinal tissues. Interestingly, besides anti-inflammation effect, it was also found that IL-1Ra possessed a significant inhibitory effect on the oxidative stress caused by ischemia/reperfusion injury. Furthermore, the expression of nuclear factor erythroid 2-related factor 2 (Nrf2) and hemeoxygenase-1 (HO-1), and the phosphorylation level of Nrf2 were greatly promoted by IL-1Ra. At the same time, IL-1Ra inhibited the mitogen-activated protein kinase (MAPKs) pathway. CONCLUSION: IL-1Ra had the protective effect against intestinal ischemia reperfusion injury, its mechanism included anti-inflammation and anti-oxidative stress in which the Nrf2/HO-1 pathway played an important role. The above-mentioned results may extend the clinical application of IL-1Ra in the treatment of intestinal ischemia reperfusion injury.

SAK-HV Promotes RAW264.7 cells Migration Mediated by MCP-1 via JNK and NF-κB Pathways.

Macrophage migration plays an essential role in immune system and is also involved in many pathological situations. However, the regulatory mechanism of macrophage migration remains to be elucidated due to its diverse responses to various stimuli. SAK-HV, a multifunctional protein possessing thrombolytic and lipid-lowering activity, can selectively induce the macrophage proliferation. Here, we reported SAK-HV significantly triggered RAW264.7 cells migration through its functional domain of SAK-mutant by activating both c-jun N-terminal kinases (JNK) and nuclear factor-κB (NF-κB) pathways. Meanwhile, SAK-HV upregulated the expression of some effector proteins, among which only the expression of Monocyte chemoattractant protein-1 (MCP-1) was inhibited by the blockade of JNK and NF-κB pathways. Further research showed that MCP-1 promoted migration ultimately by interacting with Chemokine (C-C motif) Receptor 2 (CCR2) in an autocrine manner. In summary, SAK-HV induced RAW264.7 cells migration through its SAK-mutant domain, during which MCP-1 chemokine mediated by JNK and NF-κB pathways played a key role. These results revealed a novel effect of SAK-HV on modulating macrophage migration and also deepened the understanding of its pharmacodynamics.

PM2.5 induces autophagy-mediated cell death via NOS2 signaling in human bronchial epithelium cells.

The biggest victim of ambient air pollution is the respiratory system. Mainly because of the harmful components, especially the particulate matters with an aerodynamic diameter of ≤ 2.5µm (PM2.5), can be directly inhaled and deeply penetrate into the lung alveoli, thus causing severe lung dysfunction, including chronic cough, bronchitis and asthma, even lung cancer. Unfortunately, the toxicological mechanisms of PM2.5 associations with these adverse respiratory outcomes have still not been clearly unveiled. Here, we found that PM2.5 rapidly induced inflammatory responses, oxidative injure and cell death in human bronchial epithelium cells through upregulation of IL-6 expression, ROS production and apoptosis. Furthermore, PM2.5 specifically induced nitric oxide synthase 2 (NOS2) expression and NO generation to elevate excessive autophagy. Finally, disruption of NOS2 signaling effectively blocked autophayosome formation and the subsequent cell death. Our novel findings systemically reveled the role of autophagy-mediated cell death in PM2.5-treated human bronchial epithelium cells and provided potential strategy for future clinic intervention.

A novel IL-1RA-PEP fusion protein alleviates blood-brain barrier disruption after ischemia-reperfusion in male rats.

BACKGROUND: Current options to treat clinical relapse in inflammatory central nervous system (CNS) conditions such as cerebral ischemia-reperfusion injury are limited, and agents that are more effective are required. Disruption of the blood-brain barrier is an early feature of lesion formation that correlates with clinical exacerbation and facilitates the entry of inflammatory medium and inflammatory cells. Interleukin-1 receptor antagonist (IL-1RA) is a naturally occurring anti-inflammatory antagonist of the interleukin-1 (IL-1) family. The broad-spectrum anti-inflammatory effects of IL-1RA have been investigated against various forms of neuroinflammation. However, the effect of IL-1RA on blood-brain barrier disruption following ischemia-reperfusion has not been reported. METHODS: In this study, we investigated the effects of IL-1RA and a novel protein (IL-1RA-PEP) that was fused to IL-1RA with a cell penetrating peptide, on blood-brain barrier integrity, in male rats subjected to transient middle cerebral artery occlusion. RESULTS: After intravenous administration, IL-1RA-PEP (50 mg/kg) penetrated cerebral tissues more effectively than IL-1RA. Moreover, it preserved blood-brain barrier integrity, attenuated changes in expression and localization of tight junction proteins and matrix metalloproteinases, and enhanced angiogenesis in ischemic brain tissue. Further study suggested that the effects of IL-1RA-PEP on preserving blood-brain barrier integrity might be closely correlated with the p65/NF-κB pathway, as evidenced by the effects of the inhibitor JSH-23. CONCLUSIONS: Collectively, our results demonstrated that IL-1RA-PEP could effectively penetrate the brain of rats with middle cerebral artery occlusion and ameliorate blood-brain barrier disruption. This finding might represent its novel therapeutic potential in the treatment of the cerebral ischemia-reperfusion injury.

A novel IL-1RA-PEP fusion protein with enhanced brain penetration ameliorates cerebral ischemia-reperfusion injury by inhibition of oxidative stress and neuroinflammation.

Neuroinflammation and oxidative stress are involved in cerebral ischemia-reperfusion, in which Interleukin 1 (IL-1), as an effective intervention target, is implicated. Interleukin-1 receptor antagonist (IL-1RA) is the natural inhibitor of IL-1, but blood-brain barrier (BBB) limits the brain penetration of intravenously administered IL-1RA, thereby restricting its therapeutic effect against neuroinflammation. In this study, we evaluated the potential effects of anti-inflammation and anti-oxidative stress of a novel protein IL-1RA-PEP, which fused IL-1RA with a cell penetrating peptide (CPP). Studies were carried out in transient middle cerebral artery occlusion (MCAO) in rats and oxygen glucose deprivation/reoxygenation (OGD/R) in primary cortical neurons. In MCAO rat model, IL-1RA-PEP (50mg/kg) injected i.v., penetrated BBB effectively, and alleviated brain infarction, cerebral edema, neurological deficit score and motor performance as well as inhibited the inflammatory cytokines expression. Furthermore, our results firstly showed that IL-1RA-PEP also regulated the oxidases expression, decreased the levels of NO, MDA and ROS. In addition, the inhibitory effects of IL-1RA-PEP on oxidative stress and inflammation were confirmed in rat cortical neurons induced by OGD/R, it reduced ROS, IL-6 and TNF-α. Further study showed that the effects of IL-1RA-PEP were closely associated with the NF-κB and p38 pathways which were proved respectively by their inhibitors JSH-23 and SB203580. Our results indicated that IL-1RA-PEP could effectively penetrate the brain of MCAO rats, alleviated the cerebral ischemia reperfusion injury by inhibiting neuroinflammation and oxidative stress, showing a great clinical potential for stroke.

Gold nanoparticles immobilized on metal-organic frameworks with enhanced catalytic performance for DNA detection.

In this work, gold nanoparticles (AuNPs) assembled on the surface of iron based metal-organic frameworks (MOFs), Fe-MIL-88, are facilely prepared through electrostatic interactions using polyethyleneimine (PEI) molecules as linker. The resulting hybrid materials possess synergetic peroxidase-like activity. Because iron based metal-organic frameworks, Fe-MIL-88, exhibits highly peroxidase-like activity, and AuNPs has the distinct adsorption property to single-stranded DNA (ssDNA) and double-stranded DNA (dsDNA). The peroxidase-like activity of Au@Fe-MIL-88 exhibit excellent switchable in response to specific DNA, ssDNA is easily adsorbed on the surface of the Au@Fe-MIL-88 hybrids, resulting in the reduce of the peroxidase-like activity of the hybrids. While it is recovered by the addition of target DNA, and the recovery degree is proportional to the target DNA concentration over the range of 30-150 nM with a detection limit of 11.4 nM. Based on these unique properties, we develop a label-free colorimetric method for DNA hybridization detection. In control experiment, base-mismatched DNA cannot induce recovery of the peroxidase-like activity. This detection method is simple, cheap, rapid and colorimetric.

One-pot green synthesis of graphene oxide/gold nanocomposites as SERS substrates for malachite green detection.

In this contribution, graphene oxide/gold nanoparticle (GO/AuNPs) hybrids were in situ fabricated through a green one-pot procedure by using tyrosine as an environment friendly and biocompatible reducing agent, which can be used as highly efficient surface enhanced Raman scattering (SERS) substrates with the enhancement factor at 3.8 × 10(3). The as-prepared GO/AuNPs hybrids have good biocompatibility, providing the prospect of applications for biomedicine determinations. In addition, taking the advantages of the electromagnetic and chemical enhancement mechanism and the high affinity of GO and AuNPs towards positive dyes, a sensitive, selective and label-free malachite green (MG) detection method was demonstrated. The SERS measurement showed that the minimum detection concentration of MG in water was as low as 2.5 µmol L(-1) with a linear response range from 2.5 to 100 µmol L(-1) (R(2) = 0.996). Moreover, this method can be applied to detect MG in a fishery water sample with satisfactory results.

Transient receptor potential vanilloid 2 (TRPV2), a potential novel biomarker in childhood asthma.

BACKGROUND: The presence of transient receptor potential vanilloid 2 (TRPV2) in human peripheral blood cells may suggest a role under pathological conditions. The aim of this study was to explore the relationship between the expression profile of TRPV2 gene and childhood asthma in the north of China. The effects of allergens exposure on the expression of TRPV2 gene were also investigated. METHODS: Sixty asthmatics children confirmed by physician diagnosis and 60 healthy children as a control group were recruited. Serum total IgE and specific IgE were measured. Using quantitative Reverse Transcription Polymerase Chain Reaction (qRT-PCR), TRPV2 was detected in total RNA extracted from peripheral blood lymphocytes. Student's t-test and chi-square test were used to analyze the relationship between TRPV2 transcript and different parameter variables on susceptibility of childhood asthma. Multiple logistic regression was used to analyze the associations between TRPV2 gene and allergens. RESULTS: The expression level of TRPV2 gene was increased 2.6 times in asthmatic children compared with controls (p < .01). The up-regulation of TRPV2 gene and sensitization to one of three the allergens-spring pollen, dust mite, and dog and cat hair-were correlated with childhood asthma. In addition, the hypersensitivity to spring pollen, cockroach, and dust mite and up-regulation of TRPV2 gene expression may be the risk factors for the childhood asthma in Beijing. CONCLUSIONS: The increased expression of TRPV2 gene in peripheral lymphocytes is closely correlated with childhood asthma in the north of China. This study provides a potential new biomarker of childhood asthma and lays the basis for further clarification of the pathogenesis underlying asthma.

[Quantitative method for detection of plasma lumbrokinase content and its assessment].

This study was aimed to set up and evaluate a quantitative method for detecting lumbrokinase level in plasma. The lumbrokinase was used to immunize rabbit and BALB/c mouse for preparation of rabbit or mouse-derived polyclonal antibodies, and then the standard curves were drawn up by detecting the lumbrokinase diluted in PBS using the double antibody sandwich ELISA. This method further was analyzed for its specificity, precision and recovery rate. This established double antibody sandwich ELISA was used to assay the lumbrokinase in human plasma, and the assayed results were assessed. The results showed that a double antibody sandwich ELISA for the detection of lumbrokinase has been established. And the standard curve fitting R value > 0.99, the precision assessment showed that the measured values of coefficient of variation (CV) in 3 batches were all < 15%; recovery assessment in 3 batches showed that all the measured recovery rates were > 80%; the quantitative low limit was assessed as 5 ng/ml (precision CV < 15%, recovery rate > 85%). It is concluded that this method is consistent with the criteria stipulated by the Pharmacopeia, which provides a reliable measurement method for quantitative detection of plasma lumbrokinase in clinical trials.

Expression, purification and characterization of recombinant human angiogenin in Pichia pastoris.

The potential of angiogenin (Ang) for clinical use has been highlighted in view of its important roles in inducing angiogenesis, facilitating cell proliferation, and inhibiting cell apoptosis. To produce soluble, correctly folded recombinant protein with a high yield, a DNA fragment encoding human Ang was inserted into eukaryotic expression vector pPIC9 and transformed into Pichia pastoris. The expression of recombinant human Ang (rhAng) accounted for about 70% of total secreted proteins. Purifying the Ang from the culture supernatant yielded 30 mg/L at 90% purity by chromatography with a SP Sepharose FF column. Biological assays indicated that rhAng can induce new blood-vessel formation, promote HeLa cell proliferation, increase Erk1/2 phosphorylation, and upregulate c-myc expression. Preparation of bioactive rhAng might lay the basis for further functional study, and might provide an effective strategy for large-scale production of soluble human Ang.