Synthetic bacteria designed using ars operons: a promising solution for arsenic biosensing and bioremediation.

The global concern over arsenic contamination in water due to its natural occurrence and human activities has led to the development of innovative solutions for its detection and remediation. Microbial metabolism and mobilization play crucial roles in the global cycle of arsenic. Many microbial arsenic-resistance systems, especially the ars operons, prevalent in bacterial plasmids and genomes, play vital roles in arsenic resistance and are utilized as templates for designing synthetic bacteria. This review novelty focuses on the use of these tailored bacteria, engineered with ars operons, for arsenic biosensing and bioremediation. We discuss the advantages and disadvantages of using synthetic bacteria in arsenic pollution treatment. We highlight the importance of genetic circuit design, reporter development, and chassis cell optimization to improve biosensors' performance. Bacterial arsenic resistances involving several processes, such as uptake, transformation, and methylation, engineered in customized bacteria have been summarized for arsenic bioaccumulation, detoxification, and biosorption. In this review, we present recent insights on the use of synthetic bacteria designed with ars operons for developing tailored bacteria for controlling arsenic pollution, offering a promising avenue for future research and application in environmental protection.

Long-term treatment with the mPXR agonist PCN promotes hepatomegaly and lipid accumulation without hepatocyte proliferation in mice.

Pregnane X receptor (PXR) is highly expressed in the liver and plays a pivotal role in xenobiotic and endobiotic metabolism. We previously reported that PXR activation by its specific mouse agonist pregnenolone 16α-carbonitrile (PCN) significantly induces liver enlargement and lipid accumulation. However, the effect of long-term PCN treatment on PXR and mouse liver is still unknown. This study aimed to explore the influence of long-term administration of PCN on mouse liver and hepatic lipid homeostasis. Male C57BL/6 mice were injected intraperitoneally with PCN (100 mg/kg once a week) for 42 weeks. Serum and liver samples were collected for biochemical and histological analysis. PXR activation was investigated by Western blot. Ultra-high-performance liquid chromatography coupled with electrospray ionization high-resolution mass spectrometry (UHPLC-ESI-HRMS)-based lipidomics analysis was performed to explore the change in different lipid categories. The results showed that long-term treatment with PCN significantly promoted hepatomegaly without hepatocyte proliferation and enlargement. Long-term treatment with PCN did not upregulate PXR target proteins in mice, and there was no significant upregulation of CYP3A11, CYP2B10, UGT1A1, MRP2, or MRP4. Lipidomics analysis showed obvious hepatic lipid accumulation in the PCN-treated mice, and the most significant change was found in triglycerides (TGs). Additionally, long-term treatment with PCN had no risk for carcinogenesis. These findings demonstrated that long-term PCN treatment induces hepatomegaly and lipid accumulation without hepatocyte proliferation or enlargement.

Peroxisome proliferator-activated receptor α agonist induces mouse hepatomegaly through the spatial hepatocyte enlargement and proliferation.

Peroxisome proliferator-activated receptor alpha (PPARα) activation-induced hepatomegaly is accompanied by hepatocyte hypertrophy around the central vein (CV) area and hepatocyte proliferation around the portal vein (PV) area. However, the molecular mechanisms underlying this spatial change of hepatocytes remains unclear. In this study, we examined the characteristics and possible reasons for the zonation distinction of hypertrophy and proliferation during PPARα activation-induced mouse liver enlargement. Mice were injected with corn oil or a typical mouse PPARα agonist WY-14643 (100 mg·kg-1·d-1, i.p.) for 1, 2, 3, 5 or 10 days. At each time point, the mice were sacrificed after the final dose, and liver tissues and serum were harvested for analysis. We showed that PPARα activation induced zonal changes in hepatocyte hypertrophy and proliferation in the mice. In order to determine the zonal expression of proteins related to hepatocyte hypertrophy and proliferation in PPARα-induced liver enlargement, we performed digitonin liver perfusion to separately destroy the hepatocytes around the CV or PV areas, and found that PPARα activation-induced increase magnitude of its downstream targets such as cytochrome P450 (CYP) 4 A and acyl-coenzyme A oxidase 1 (ACOX1) levels around the CV area were higher compared with those around the PV area. Upregulation of proliferation-related proteins such as cell nuclear antigen (PCNA) and cyclin A1 (CCNA1) after WY-14643-induced PPARα activation mainly occurred around the PV area. This study reveals that the zonal expression of PPARα targets and proliferation-related proteins is responsible for the spatial change of hepatocyte hypertrophy and proliferation after PPARα activation. These findings provide a new insight into the understanding of PPARα activation-induced liver enlargement and regeneration.

Designed bacteria based on natural pbr operons for detecting and detoxifying environmental lead: A mini-review.

Lead (Pb), a naturally occurring element, is redistributed in the environment mainly due to anthropogenic activities. Pb pollution is a crucial public health problem worldwide due to its adverse effects. Environmental bacteria have evolved various protective mechanisms against high levels of Pb. The pbr operon, first identified in Cupriavidus metallidurans CH34, encodes a unique Pb(II) resistance mechanism involving transport, efflux, sequestration, biomineralization, and precipitation. Similar pbr operons are gradually found in diverse bacterial strains. This review focuses on the pbr-encoded Pb(II) resistance system. It summarizes various whole-cell biosensors harboring artificially designed pbr operons for Pb(II) biomonitoring with fluorescent, luminescent, and colorimetric signal output. Optimization of genetic circuits, employment of pigment-based reporters, and screening of host cells are promising in improving the sensitivity, selectivity, and response range of whole-cell biosensors. Engineered bacteria displaying Pb(II) binding and sequestration proteins, including PbrR and its derivatives, PbrR2 and PbrD, for adsorption are involved. Although synthetic bacteria show great potential in determining and removing Pb at the nanomolar level for environmental protection and food safety, some challenges must be addressed to meet demanding application requirements.

Survey-Based Analysis of the Clinical Treatment Status of Irritable Bowel Syndrome in Korea.

BACKGROUND: The quality-of-life of patients with irritable bowel syndrome is low; incorrect diagnosis/treatment causes economic burden and inappropriate consumption of medical resources. This survey-based study aimed to analyze the current status of irritable bowel syndrome treatment to examine differences in doctors' perceptions of the disease, and treatment patterns. METHODS: From October 2019 to February 2020, the irritable bowel syndrome and Intestinal Function Research Study Group of the Korean Society of Neurogastroenterology and Motility conducted a survey on doctors working in primary, secondary, and tertiary healthcare institutions. The questionnaire included 37 items and was completed anonymously using the NAVER platform (a web-based platform), e-mails, and written forms. RESULTS: A total of 272 doctors responded; respondents reported using the Rome IV diagnostic criteria (amended in 2016) for diagnosing and treating irritable bowel syndrome. Several differences were noted between the primary, secondary, and tertiary physicians' groups. The rate of colonoscopy was high in tertiary healthcare institutions. During a colonoscopy, the necessity of random biopsy was higher among physicians who worked at tertiary institutions. 'The patient did not adhere to the diet' as a reason for ineffectiveness using low-fermentable oligo-, di-, and mono-saccharides, and polyols diet treatment was higher among physicians in primary/secondary institutions, and 'There are individual differences in terms of effectiveness' was higher among physicians in tertiary institutions. In irritable bowel syndrome constipation predominant subtype, the use of serotonin type 3 receptor antagonist (ramosetron) and probiotics was higher in primary/secondary institutions, while serotonin type 4 receptor agonist was used more in tertiary institutions. In irritable bowel syndrome diarrhea predominant subtype, the use of antispasmodics was higher in primary/secondary institutions, while the use of serotonin type 3 receptor antagonist (ramosetron) was higher in tertiary institutions. CONCLUSION: Notable differences were observed between physicians in primary/secondary and tertiary institiutions regarding the rate of colonoscopy, necessity of random biopsy, the reason for the ineffectiveness of low-fermentable oligo-, di-, and mono-saccharides, and polyols diet, and use of drug therapy in irritable bowel syndrome. In South Korea, irritable bowel syndrome is diagnosed and treated according to the Rome IV diagnostic criteria, revised in 2016.

PXR mediates mifepristone-induced hepatomegaly in mice.

Mifepristone (Mif), an effective synthetic steroidal antiprogesterone drug, is widely used for medical abortion and pregnancy prevention. Due to its anti-glucocorticoid effect, high-dose Mif is also used to treat Cushing's syndrome. Mif was reported to active pregnane X receptor (PXR) in vitro and PXR can induce hepatomegaly via activation and interaction with yes-associated protein (YAP) pathway. High-dose Mif was reported to induce hepatomegaly in rats and mice, but the underlying mechanism remains unclear. Here, the role of PXR was studied in Mif-induced hepatomegaly in C57BL/6 mice and Pxr-knockout mice. The results demonstrated that high-dose Mif (100 mg · kg-1 · d-1, i.p.) treatment for 5 days significantly induced hepatomegaly with enlarged hepatocytes and promoted proliferation, but low dose of Mif (5 mg · kg-1 · d-1, i.p.) cannot induce hepatomegaly. The dual-luciferase reporter gene assays showed that Mif can activate human PXR in a concentration-dependent manner. In addition, Mif could promote nuclear translocation of PXR and YAP, and significantly induced the expression of PXR, YAP, and their target proteins such as CYP3A11, CYP2B10, UGT1A1, ANKRD, and CTGF. However, Mif (100 mg · kg-1 · d-1, i.p.) failed to induce hepatomegaly in Pxr-knockout mice, as well as hepatocyte enlargement and proliferation, further indicating that Mif-induced hepatomegaly is PXR-dependent. In summary, this study demonstrated that PXR-mediated Mif-induced hepatomegaly in mice probably via activation of YAP pathway. This study provides new insights in Mif-induced hepatomegaly, and provides novel evidence on the crucial function of PXR in liver enlargement and regeneration.

Hepatic Vps33b deficiency aggravates cholic acid-induced cholestatic liver injury in male mice.

Vacuolar protein sorting 33B (VPS33B) is important for intracellular vesicular trafficking process and protein interactions, which is closely associated with the arthrogryposis, renal dysfunction, and cholestasis syndrome. Our previous study has shown a crucial role of Vps33b in regulating metabolisms of bile acids and lipids in hepatic Vps33b deficiency mice with normal chow, but it remains unknown whether VPS33B could contribute to cholestatic liver injury. In this study we investigated the effects of hepatic Vps33b deficiency on bile acid metabolism and liver function in intrahepatic cholestatic mice. Cholestasis was induced in Vps33b hepatic knockout and wild-type male mice by feeding 1% CA chow diet for 5 consecutive days. We showed that compared with the wild-type mice, hepatic Vps33b deficiency greatly exacerbated CA-induced cholestatic liver injury as shown in markedly increased serum ALT, AST, and ALP activities, serum levels of total bilirubin, and total bile acid, as well as severe hepatocytes necrosis and inflammatory infiltration. Target metabolomics analysis revealed that hepatic Vps33b deficiency caused abnormal profiles of bile acids in cholestasis mice, evidenced by the upregulation of conjugated bile acids in serum, liver, and bile. We further demonstrated that the metabolomics alternation was accompanied by gene expression changes in bile acid metabolizing enzymes and transporters including Cyp3a11, Ugt1a1, Ntcp, Oatp1b1, Bsep, and Mrp2. Overall, these results suggest a crucial role of hepatic Vps33b deficiency in exacerbating cholestasis and liver injury, which is associated with the altered metabolism of bile acids.

Natural product-based screening led to the discovery of a novel PXR agonist with anti-cholestasis activity.

Cholestasis is a major cause of a series of bile flow malfunction-related liver diseases. Pregnane X receptor (PXR) is a key regulator in endo- and xeno-biotics metabolism, which has been considered as a promising therapeutic target for cholestasis. In this study we conducted human PXR (hPXR) agonistic screening using dual-luciferase reporter gene assays, which led to discovering a series of potent hPXR agonists from a small Euphorbiaceae diterpenoid library, containing 35 structurally diverse diterpenoids with eight different skeleton types. The most active compound 6, a lathyrane diterpenoid (5/11/3 ring system), dose-dependently activated hPXR with a high selectivity, and significantly upregulated the expression of hPXR downstream genes CYP3A4 and UGT1A1. In LCA-induced cholestasis mouse model, administration of compound 6 (50 mg· kg-1. d-1, ip) for 7 days significantly suppressed liver necrosis and decreased serum levels of AST, ALT, Tbili, ALP, and TBA, ameliorating LCA-induced cholestatic liver injury. We further revealed that compound 6 exerted its anti-cholestatic efficacy via activation of PXR pathway, accelerating the detoxification of toxic BAs and promoting liver regeneration. These results suggest that lathyrane diterpenoids may serve as a promising scaffold for future development of anti-cholestasis drugs.

Indigoidine biosynthesis triggered by the heavy metal-responsive transcription regulator: a visual whole-cell biosensor.

During the last few decades, whole-cell biosensors have attracted increasing attention for their enormous potential in monitoring bioavailable heavy metal contaminations in the ecosystem. Visual and measurable output signals by employing natural pigments have been demonstrated to offer another potential choice to indicate the existence of bioavailable heavy metals in recent years. The biosynthesis of the blue pigment indigoidine has been achieved in E. coli following heterologous expression of both BpsA (a single-module non-ribosomal peptide synthetase) and PcpS (a PPTase to activate apo-BpsA). Moreover, we demonstrated herein the development of the indigoidine-based whole-cell biosensors to detect bioavailable Hg(II) and Pb(II) in water samples by employing metal-responsive transcriptional regulator MerR and PbrR as the sensory elements, and the indigoidine biosynthesis gene cluster as a reporter element. The resulting indigoidine-based biosensors presented a good selectivity and high sensitivity to target metal ions. High concentration of target metal exposure could be clearly recognized by the naked eye due to the color change by the secretion of indigoidine, and quantified by measuring the absorbance of the culture supernatants at 600 nm. Dose-response relationships existed between the exposure concentrations of target heavy metals and the production of indigoidine. Although fairly good linear relationships were obtained in a relatively limited concentration range of the concentrations of heavy metal ions, these findings suggest that genetically controlled indigoidine biosynthesis triggered by the MerR family transcriptional regulator can enable a sensitive, visual, and qualitative whole-cell biosensor for bioindicating the presence of bioaccessible heavy metal in environmental water samples. KEY POINTS: • Biosynthesis pathway of indigoidine reconstructed in a high copy number plasmid in E. coli. • Visual and colorimetric detection of Hg(II) and Pb(II) by manipulation of indigoidine biosynthesis through MerR family metalloregulator. •Enhanced detection sensitivity toward Hg(II) and Pb(II) achieved using novel pigment-based whole-cell biosensors.

Design, Synthesis and Evaluation of Novel Derivatives of Curcuminoids with Cytotoxicity.

Curcumin and curcuminoids have been discussed frequently due to their promising functional groups (such as scaffolds of α,ß-unsaturated ß-diketone, α,ß-unsaturated ketone and ß'-hydroxy-α,ß-unsaturated ketone connected with aromatic rings on both sides) that play an important role in various bioactivities, including antioxidant, anti-inflammatory, anti-proliferation and anticancer activity. A series of novel curcuminoid derivatives (a total of 55 new compounds) and three reference compounds were synthesized with good yields using three-step organic synthesis. The anti-proliferative activities of curcumin derivatives were examined for six human cancer cell lines: HeLaS3, KBvin, MCF-7, HepG2, NCI-H460 and NCI-H460/MX20. Compared to the IC50 values of all the synthesized derivatives, most α,ß-unsaturated ketones displayed potent anti-proliferative effects against all six human cancer cell lines, whereas ß'-hydroxy-α,ß-unsaturated ketones and α,ß-unsaturated ß-diketones presented moderate anti-proliferative effects. Two potent curcuminoid derivatives were found among all the novel derivatives and reference compounds: (E)-5-hydroxy-7-phenyl-1-(3,4,5-trimethoxyphenyl)hept-1-en-3-one (compound 3) and (1E,4E)-1,7-bis(3,4,5-trimethoxyphenyl)hepta-1,4-dien-3-one (compound MD12a). These were selected for further analysis after the evaluation of their anti-proliferative effects against all human cancer cell lines. The results of apoptosis assays revealed that the number of dead cells was increased in early apoptosis and late apoptosis, while cell proliferation was also decreased after applying various concentrations of (E)-5-hydroxy-7-phenyl-1-(3,4,5-trimethoxyphenyl)hept-1-en-3-one (compound 3) and (1E,4E)-1,7-bis(3,4,5-trimethoxyphenyl)hepta-1,4-dien-3-one (compound MD12a) to MCF-7 and HpeG2 cancer cells. Analysis of the gene expression arrays showed that three genes (GADD45B, SESN2 and BBC3) were correlated with the p53 pathway. From the quantitative PCR analysis, it was seen that (1E,4E)-1,7-bis(3,4,5-trimethoxyphenyl)hepta-1,4-dien-3-one (compound MD12a) effectively induced the up-regulated expression of GADD45B, leading to the suppression of MCF-7 cancer cell formation and cell death. Molecular docking analysis was used to predict and sketch the interactions of the GADD45B-α,ß-unsaturated ketone complex for help in drug design.

Recent advances in bacterial biosensing and bioremediation of cadmium pollution: a mini-review.

Cadmium (Cd) pollution has become a global environmental issue because Cd gets easily accumulated and translocated in the food chain, threatening human health. Considering the detrimental effects and non-biodegradability of environmental Cd, this is an urgent issue that needs to be addressed through the development of robust, cost-effective, and eco-friendly green routes for monitoring and remediating toxic levels of Cd. This article attempts to review various bacterial approaches toward biosensing and bioremediation of Cd in the environment. This review focuses on the recent development of bacterial cell-based biosensors for the detection of bioavailable Cd and the bioremediation of toxic Cd by natural or genetically-engineered bacteria. The present limitations and future perspectives of these available bacterial approaches are outlined. New trends for integrating synthetic biology and metabolic engineering into the design of bacterial biosensors and bioadsorbers are additionally highlighted.

Nakamurella flava sp. nov., a novel endophytic actinobacterium isolated from Mentha haplocalyx Briq.

A Gram-stain-positive, aerobic, coccus-shaped, non-spore-forming actinobacterium, designated strain N5BH11T, was isolated from a surface-sterilized sample of Mentha haplocalyx Briq. collected from Guizhou, PR China and tested by a polyphasic approach to determine its taxonomic position. Strain N5BH11T grew optimally at 30 °C, pH 6.0-7.0. Substrate mycelia and aerial mycelia were not formed, and no diffusible pigments were observed on the media tested. Phylogenetic analysis based on 16S rRNA gene sequence suggested that strain N5BH11T belonged to the genus Nakamurella and had the highest 16S rRNA gene sequence similarity to Nakamurella flavida DS-52T (98.1 %). The DNA G+C content of strain N5BH11T was 71.6 mol%. The average nucleotide identity values between strain N5BH11T and the type strains of Nakamurella panacisegetis, Nakamurella multipartita and Nakamurella lactea were 74.0, 76.5 and 73.6 %, respectively. The estimated DDH values between strain N5BH11T and the type strains of N. panacisegetis, N. multipartita and N. lactea were 20.3%, 21.4 and 20.2 %, respectively. The cell-wall peptidoglycan contained meso-diaminopimelic acid, and MK-8(H4) was the predominant menaquinone. The predominant polar lipids were diphosphatidylglycerol, phosphatidylethanolamine, phosphatidylmonomethylethanolamine and unidentified phospholipids. The major fatty acids were iso-C15 : 0, anteiso-C15 : 0, C16 : 0 and C16 : 1ω7c. On the basis of the results of phylogenetic analysis and phenotypic and chemotaxonomic characteristics, strain N5BH11T represents a novel species of the genus Nakamurella, for which the name Nakamurella flava sp. nov. is proposed. The type strain is N5BH11T (=KCTC 49196T=CGMCC 4.7524T).

Induction of autophagic cell death in human ovarian carcinoma cells by Antrodia salmonea through increased reactive oxygen species generation.

We reported in our previously executed studies that the fermented culture broth of Antrodia salmonea (AS), a mushroom used in Taiwanese folk medicine induced reactive oxygen species (ROS)-mediated apoptosis in human ovarian carcinoma cells. In this study, we studied the anticancer efficacies of AS (0-240 µg/ml) by examining the key molecular events implicated in cell death associated with autophagy in SKOV-3 and A2780 human ovarian carcinoma cells and clarified the fundamental molecular mechanisms. Treatment of ovarian carcinoma cells with AS-induced autophagic cell death mediated by increased microtubule-associated protein LC3-II, GFP-LC3 puncta, and acidic vesicular organelle (AVO) formation. These events are linked with the activation of p62/SQSTM1, the inhibition of ATG4B, the expression of ATG7, and the dysregulation of Beclin-1/Bcl-2 (i.e., B-cell lymphoma 2). N-acetylcysteine inhibited AS-induced ROS generation, which in turn constricted AS-induced LC3 conversion, AVO formation, and ATG4B inhibition, indicating ROS-mediated autophagy cell death. In addition, the 3-methyladenine (3-MA) or chloroquine (CQ)-induced autophagy inhibition decreased AS-induced apoptosis. Additionally, apoptosis inhibition by Z-VAD-FMK, a pan-caspase inhibitor, substantially suppressed AS-induced autophagy. Furthermore, AS-inhibited HER-2/ neu and PI3K/AKT signaling pathways which were reversed by autophagy inhibitors 3-MA and CQ. Thus, A. salmonea is a potential chemopreventive agent that is capable of activating ROS-mediated autophagic cell death in ovarian carcinoma cells.

Development of a novel bacterial surface display system using truncated OmpT as an anchoring motif.

OBJECTIVES: An efficient bacterial surface display system based on the anchoring motif derived from Escherichia coli (E. coli) outer membrane protease OmpT was developed in this study. RESULTS: Referring to the classical Lpp-OmpA (LOA) display system, the signal peptide and nine amino acids of mature Lpp were fused to the transmembrane domain comprising five ß-strands of truncated OmpT to generate a novel Lpp-OmpT (LOT) display system. The C-terminal fusion strategy was used to fuse a small peptide (His tag) and red fluorescent protein (mCherry) to the C-terminus of LOT. Cell surface exposure of His tag and mCherry were compared between the LOA and LOT display systems. E. coli expressing LOT-His tag adsorbed more Cu2+ than E. coli expressing LOA-His tag. E. coli expressing both LOT-mCherry-His tag and LOA-mCherry-His tag adhered to Cu2+ chelating sepharose beads, and adhered cells could be dissociated from the beads after excess Cu2+ treatment. More importantly, compared with the LOA system, a higher amount of LOT-mCherry-His tag hybrid protein was demonstrated to be localized at the outer membrane by both fluorescence spectrophotometric determination of cell fractions and cell-surface immunofluorescence assay. CONCLUSIONS: These results suggest that genetically modified OmpT can be used as a potential anchoring motif to efficiently and stably display polypeptides and proteins, and that the LOT system could be used in a variety of biotechnological and industrial processes.

Brachybacterium endophyticum sp. nov., a novel endophytic actinobacterium isolated from bark of Scutellaria baicalensis Georgi.

A Gram-positive, aerobic, coccus-shaped, non-spore-forming actinobacterium, designated strain M1HQ-2T, was isolated from a surface-sterilized bark of Scutellaria baicalensis Georgi collected from Guizhou, China and tested using a polyphasic approach to determine its taxonomic position. Strain M1HQ-2T grew at 4-37 °C (optimum, 30 °C), pH 5.0-11.0 (pH 8.0) and in the presence of 0-15 % (w/v) NaCl (1-3 %). Substrate mycelia and aerial mycelia were not formed, and diffusible pigments were not observed on any media tested. Phylogenetic analysis based on 16S rRNA gene sequence indicated that strain M1HQ-2T belonged to the genus Brachybacterium and had the highest 16S rRNA gene sequence similarity of 97.6 % to Brachybacteriumsquillarum M-6-3T. Strain M1HQ-2T contained MK-7 as the dominant menaquinone. The cell-wall peptidoglycan contained meso-diaminopimelic acid. The polar lipids profile of strain M1HQ-2T contained diphosphatidylglycerol, phosphatidylglycerol, an unidentified phospholipid and an unidentified lipid. The predominant fatty acids were anteiso-C15 : 0 and anteiso-C17 : 0. The DNA G+C content of strain M1HQ-2T was 71.0 mol%. The average nucleotide identity value between strain M1HQ-2T and type strain of Brachybacterium sacelli was 76.7 %. The estimated DNA-DNA hybridization value between strain M1HQ-2T and type strain of B. sacelli was 20.6 %. On the basis of phylogenetic analysis, chemotaxonomic characteristics and phenotypic data, strain M1HQ-2T represents a novel species of the genus Brachybacterium, for which the name Brachybacteriumendophyticum sp. nov. is proposed. The type strain is M1HQ-2T (=KCTC 49087T=CGMCC 1.16391T).

Surface display of metal binding domain derived from PbrR on Escherichia coli specifically increases lead(II) adsorption.

OBJECTIVES: To improve the Pb2+ biosorption capacity of the potential E. coli biosorbent, a putative Pb2+ binding domain (PbBD) derived from PbrR was efficiently displayed on to the E. coli cell surface. RESULTS: The PbBD was obtained by truncating the N-terminal DNA-binding domain and C-terminal redundant amino acid residues of the Pb2+-sensing transcriptional factor PbrR. Whole-cell sorbents were constructed with the full-length PbrR and PbBD of PbrR genetically engineered onto the surface of E. coli cells using Lpp-OmpA as the anchor. Followed by a 1.71-fold higher display of PbBD than PbrR, the presence of PbBD on the surface of E. coli cells enabled a 1.92-fold higher Pb2+ biosorption than that found in PbrR-displayed cells. Specific Pb2+ binding via PbBD was the same as Pb2+ binding via the full-length PbrR, with no observable decline even in the presence of Zn2+ and Cd2+. CONCLUSIONS: Since surface-engineered E. coli cells with PbBD increased the Pb2+ binding capacity and did not affect the adsorption selectivity, this suggests that surface display of the metal binding domain derived from MerR-like proteins may be used for the bioremediation of specific toxic heavy metals.

[Regulation of P-glycoprotein gene expression by PKC/NF-κB-PXR signaling pathway].

P-glycoprotein (P-gp), an ATP binding cassette protein, plays a major role in efflux transport of drugs and xenobiotics due to its abundant expression on several barriers. This study aimed to investigate the potential role of PKC/NF-κB-PXR signaling pathway in modulation of P-gp gene expression in human colon adenocarcinoma LS174T. The effect of PMA on MDR1 luciferase activity was investigated by PXR-MDR1 dual luciferase reporter gene assay. Real-time qPCR assay and Western blot analysis were used to study the gene expression of P-gp and NF-κB, respectively. Compared to the vehicle-treated group, PMA statistically decreased P-gp luciferase activity, mRNA expression and protein expression. Moreover, PMA treatment yielded a significant and dose-dependent increase in RelA/p65 translocation to nucleus. Meanwhile, a remarkable increase of the pho-IκBα status was observed in LS174T cells after treatment with PMA (1-100 nmol·L(-1)). In addition, knockdown of PKCα, NF-κB or PXR can significantly attenuate PMA-induced P-gp suppression. These results suggested that PKC/NF-κB-PXR signaling pathway might play crucial roles in modulation of P-gp gene expression.

Isolation and characterization of antimicrobial peptides from healthy male urine.

A complex of low-molecular cationic peptides, extracted from human urine by a combination membrane ultrafiltration and weak cation exchange chromatography, was characterized in this study. It provides a simpler solution for the development of novel antimicrobial peptides from biological liquid waste.

Stereoselective Synthesis of Spiro Bis-C,C-α-arylglycosides by Tandem Heck Type C-Glycosylation and Friedel-Crafts Cyclization.

Spiro bis-C,C-α-arylglycosides were synthesized in three steps in 78-85% overall yields starting from exo-glycals. The initial Heck type C-aryl addition of exo-glycals with arylboronic acids afforded α-aryl-ß-substituted C-glycosides with exclusive α-stereoselectivity. Among the products, ß-ethanal α-aryl C-glycosides further reacted with alkylthiol in the presence of InCl3, followed by in situ Friedel-Crafts cyclization to yield the desirable final products. We proposed a mechanism to explain how the α-aryl group serves as a main determinant of the cyclization.

Schisandrol B protects against acetaminophen-induced acute hepatotoxicity in mice via activation of the NRF2/ARE signaling pathway.

AIM: The nuclear factor erythroid 2-related factor 2 (NRF2) acts through the antioxidant response element (ARE) to regulate the expression of many detoxifying and antioxidant genes responsible for cytoprotective processes. We previously reported that Schisandrol B (SolB) isolated from Schisandra sphenanthera produced a protective effect against acetaminophen (APAP)-induced liver injury. In this study we investigated whether the NRF2/ARE signaling pathway was involved in this hepato-protective effect. METHODS: Male C57BL/6 mice were treated with SolB (200 mg · kg(-1) · d(-1), ig) for 3 d before injection of APAP (400 mg/kg, ip). Serum and liver tissue samples were collected 6 h later. The mRNA and protein expression were measured using qRT-PCR and Western blot assay, respectively. The activation of NRF2 was examined in HepG2 cells using luciferase reporter gene assay. RESULTS: SolB pretreatment significantly alleviated the hepatic injury (large patchy necrosis and hyperemia of the hepatic sinus), the increase of serum AST, ALT levels and hepatic MDA contents, and the decrease of liver and mitochondrial glutathione levels in APAP-treated mice. Furthermore, SolB pretreatment significantly increased nuclear accumulation of NRF2 and increased hepatic expression of NRF2 downstream proteins, including GCLC, GSR, NQO1, GSTs, MRP2, MRP3 and MRP4 in APAP-treated mice. Moreover, treatment with SolB (2.5-20 µmol/L) dose-dependently increased the activity of NRF2 reporter gene in HepG2 cells. CONCLUSION: SolB exhibits a remarkable protective effect against APAP-induced hepatotoxicity, partially via activation of the NRF2/ARE pathway and regulation of NRF2 target genes, which induce detoxification and increase antioxidant capacity.