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Aims Despite massive efforts, we remain far behind in our attempts to identify effective therapies to treat heart failure with preserved ejection fraction (HFpEF). Diastolic function is critically regulated by sarcoplasmic/endoplasmic reticulum (SR) calcium ATPase 2a (SERCA2a), which forms a functional cardiomyocyte (CM) microdomain where 3′,5′-cyclic adenosine monophosphate (cAMP) produced upon β-adrenergic receptor (β-AR) stimulation leads to phospholamban (PLN) phosphorylation and facilitated Ca2+ re-uptake. Methods and results To visualize real-time cAMP dynamics in the direct vicinity of SERCA2a in healthy and diseased myocytes, we generated a novel mouse model on the leprdb background that stably expresses the Epac1-PLN Förster resonance energy transfer biosensor. Mice homozygous for the leprdb mutation (db/db) developed obesity and type 2 diabetes and presented with a HFpEF phenotype, evident by mild left ventricular hypertrophy and elevated left atria filling pressures. Live cell imaging uncovered a substantial β2-AR subtype stimulated cAMP response within the PLN/SERCA2a microdomain of db/db but not healthy control (db/+) CMs, which was accompanied by increased PLN phosphorylation and accelerated calcium re-uptake. Importantly, db/db CMs also exhibited a desensitization of β1-AR stimulated cAMP pools within the PLN/SERCA2a microdomain, which was accompanied by a blunted lusitropic effect, suggesting that the increased β2-AR control is an intrinsic compensatory mechanism to maintain PLN/SERCA2a-mediated calcium dynamics and cardiac relaxation. Mechanistically, this was due to a local loss of cAMP-degrading phosphodiesterase 4 associated specifically with the PLN/SERCA2a complex. Conclusion These newly identified alterations of cAMP dynamics at the subcellular level in HFpEF should provide mechanistic understanding of microdomain remodelling and pave the way towards new therapies. [ABSTRACT FROM AUTHOR]

AU-rich elements (AREs) are 3' UTR cis-regulatory elements that regulate the stability of mRNAs. Consensus ARE motifs have been determined, but little is known about how differences in 3' UTR sequences that conform to these motifs affect their function. Here, we use functional annotation of sequences from 3' UTRs (fast-UTR), a massively parallel reporter assay (MPRA), to investigate the effects of 41,288 3' UTR sequence fragments from 4653 transcripts on gene expression and mRNA stability in Jurkat and Beas2B cells. Our analyses demonstrate that the length of an ARE and its registration (the first and last nucleotides of the repeating ARE motif) have significant effects on gene expression and stability. Based on this finding, we propose improved ARE classification and concomitant methods to categorize and predict the effect of AREs on gene expression and stability. Finally, to investigate the advantages of our general experimental design we examine other motifs including constitutive decay elements (CDEs), where we show that the length of the CDE stem-loop has a significant impact on steady-state expression and mRNA stability. We conclude that fast-UTR, in conjunction with our analytical approach, can produce improved yet simple sequence-based rules for predicting the activity of human 3' UTRs.

Central obesity with cardiometabolic syndrome (CMS) is a major global contributor to human disease, and effective therapies are needed. Here, we show that cyclic GMP-selective phosphodiesterase 9A inhibition (PDE9-I) in both male and ovariectomized female mice suppresses preestablished severe diet-induced obesity/CMS with or without superimposed mild cardiac pressure load. PDE9-I reduces total body, inguinal, hepatic, and myocardial fat; stimulates mitochondrial activity in brown and white fat; and improves CMS, without significantly altering activity or food intake. PDE9 localized at mitochondria, and its inhibition in vitro stimulated lipolysis in a PPARα-dependent manner and increased mitochondrial respiration in both adipocytes and myocytes. PPARα upregulation was required to achieve the lipolytic, antiobesity, and metabolic effects of PDE9-I. All these PDE9-I-induced changes were not observed in obese/CMS nonovariectomized females, indicating a strong sexual dimorphism. We found that PPARα chromatin binding was reoriented away from fat metabolism-regulating genes when stimulated in the presence of coactivated estrogen receptor-α, and this may underlie the dimorphism. These findings have translational relevance given that PDE9-I is already being studied in humans for indications including heart failure, and efficacy against obesity/CMS would enhance its therapeutic utility.

The unicellular parasite Trypanosoma brucei is transmitted between mammals by tsetse flies. Following the discovery that flagellar phosphodiesterase PDEB1 is required for trypanosomes to move in response to signals in vitro (social motility), we investigated its role in tsetse flies. Here we show that PDEB1 knockout parasites exhibit subtle changes in movement, reminiscent of bacterial chemotaxis mutants. Infecting flies with the knockout, followed by live confocal microscopy of fluorescent parasites within dual-labelled insect tissues, shows that PDEB1 is important for traversal of the peritrophic matrix, which separates the midgut lumen from the ectoperitrophic space. Without PDEB1, parasites are trapped in the lumen and cannot progress through the cycle. This demonstrates that the peritrophic matrix is a barrier that must be actively overcome and that the parasite's flagellar cAMP signaling pathway facilitates this. Migration may depend on perception of chemotactic cues, which could stem from co-infecting parasites and/or the insect host.

VHH antibodies or nanobodies, which are antigen-binding domains of heavy chain antibodies from camelid species, have several advantageous characteristics, including compact molecular size, high productibility in bacteria and easy engineering for functional improvement. Focusing on these advantages of VHHs, we attempted to establish an immunoassay system for detection of Legionella , the causative pathogen of Legionnaires' disease. A VHH phage display library was constructed using cDNA from B cells of alpacas immunized with Legionella pneumophila serogroup1 (LpSG1). Through biopanning, two specific VHH clones were isolated and used to construct a Legionella detection system based on the latex agglutination assay. After engineering the VHHs and improving the assay system, the sensitive detection system was successfully established for the LpSG1 antigen. The immunoassay developed in this study should be useful in easy and sensitive detection of Legionella , the causative agent of Legionnaires' disease, which is a potentially fatal pneumonia. [ABSTRACT FROM AUTHOR]

Two cAMP signaling compartments centered on adenylyl cyclase (AC) exist in human airway smooth muscle (HASM) cells, one containing β2-adrenergic receptor AC6 and another containing E prostanoid receptor AC2. We hypothesized that different PDE isozymes selectively regulate cAMP signaling in each compartment. According to RNA-sequencing data, 18 of 24 PDE genes were expressed in primary HASM cells derived from age- and sex-matched donors with and without asthma. PDE8A was the third most abundant of the cAMP-degrading PDE genes, after PDE4A and PDE1A. Knockdown of PDE8A using shRNA evoked twofold greater cAMP responses to 1 μM forskolin in the presence of 3-isobutyl-1-methylxanthine. Overexpression of AC2 did not alter this response, but overexpression of AC6 increased cAMP responses an additional 80%. We examined cAMP dynamics in live HASM cells using a fluorescence sensor. PF-04957325, a PDE8-selective inhibitor, increased basal cAMP concentrations by itself, indicating a significant basal level of cAMP synthesis. In the presence of an AC inhibitor to reduce basal signaling, PF-04957325 accelerated cAMP production and increased the inhibition of cell proliferation induced by isoproterenol, but it had no effect on cAMP concentrations or cell proliferation regulated by prostaglandin E2. Lipid raft fractionation of HASM cells revealed PDE8A immunoreactivity in buoyant fractions containing caveolin-1 and AC5/6 immunoreactivity. Thus, PDE8 is expressed in lipid rafts of HASM cells, where it specifically regulates β2-adrenergic receptor AC6 signaling without effects on signaling by the E prostanoid receptors 2/4-AC2 complex. In airway diseases such as asthma and chronic obstructive pulmonary disease, PDE8 may represent a novel therapeutic target to modulate HASM responsiveness and airway remodeling.

Osteoarthritis (OA) is a disease of the joints, characterized by chronic inflammation, cartilage destruction and extracellular matrix (ECM) remodeling. Aberrant chondrocyte hypertrophy promotes cartilage destruction and OA development. Collagen X, the biomarker of chondrocyte hypertrophy, is upregulated by runt-related transcription factor 2 (Runx2), which is mediated by the bone morphogenetic protein 4 (BMP4)/Smad1 signaling pathway. BMP binding endothelial regulator (BMPER), a secreted glycoprotein, acts as an agonist of BMP4. 5,7,3',4'-tetramethoxyflavone (TMF) is a natural flavonoid derived from Murraya exotica L. Results of our previous study demonstrated that TMF exhibits chondroprotective effects against OA development through the activation of Forkhead box protein O3a (FOXO3a) expression. However, whether TMF suppresses chondrocyte hypertrophy through activation of FOXO3a expression and inhibition of BMPER/BMP4/Smad1 signaling remains unknown. Results of the present study revealed that TMF inhibited collagen X and Runx2 expression, inhibited BMPER/BMP4/Smad1 signaling, and activated FOXO3a expression; thus, protecting against chondrocyte hypertrophy and OA development. However, BMPER overexpression and FOXO3a knockdown impacted the protective effects of TMF. Thus, TMF inhibited chondrocyte hypertrophy in OA cartilage through mediating the FOXO3a/BMPER signaling pathway. [ABSTRACT FROM AUTHOR]

Farnesylation and carboxymethylation of KRAS4b (Kirsten rat sarcoma isoform 4b) are essential for its interaction with the plasma membrane where KRAS-mediated signaling events occur. Phosphodiesterase-δ (PDEδ) binds to KRAS4b and plays an important role in targeting it to cellular membranes. We solved structures of human farnesylated-methylated KRAS4b in complex with PDEδ in two different crystal forms. In these structures, the interaction is driven by the C-terminal amino acids together with the farnesylated and methylated C185 of KRAS4b that binds tightly in the central hydrophobic pocket present in PDEδ. In crystal form II, we see the full-length structure of farnesylated-methylated KRAS4b, including the hypervariable region. Crystal form I reveals structural details of farnesylated-methylated KRAS4b binding to PDEδ, and crystal form II suggests the potential binding mode of geranylgeranylated-methylated KRAS4b to PDEδ. We identified a 5-aa-long sequence motif (Lys-Ser-Lys-Thr-Lys) in KRAS4b that may enable PDEδ to bind both forms of prenylated KRAS4b. Structure and sequence analysis of various prenylated proteins that have been previously tested for binding to PDEδ provides a rationale for why some prenylated proteins, such as KRAS4a, RalA, RalB, and Rac1, do not bind to PDEδ. Comparison of all four available structures of PDEδ complexed with various prenylated proteins/peptides shows the presence of additional interactions due to a larger protein-protein interaction interface in KRAS4b-PDEδ complex. This interface might be exploited for designing an inhibitor with minimal off-target effects.

Thrombocytopenia is closely linked with hemorrhagic diseases, for which induction of thrombopoiesis shows promise as an effective treatment. Polyphenols widely exist in plants and manifest antioxidation and antitumour activities. In this study, we investigated the thrombopoietic effect and mechanism of 3,3′,4′-trimethylellagic acid (TMEA, a polyphenol in Sanguisorba officinalis L.) using in silico prediction and experimental validation. A KEGG analysis indicated that PI3K/Akt signalling functioned as a crucial pathway. Furthermore, the virtual molecular docking results showed high-affinity binding (a docking score of 6.65) between TMEA and mTOR, suggesting that TMEA might target the mTOR protein to modulate signalling activity. After isolation of TMEA, in vitro and in vivo validation revealed that this compound could promote megakaryocyte differentiation/maturation and platelet formation. In addition, it enhanced the phosphorylation of PI3K, Akt, mTOR, and P70S6K and increased the expression of GATA-1 and NF-E2, which confirmed the mechanism prediction. In conclusion, our findings are the first to demonstrate that TMEA may provide a novel therapeutic strategy that relies on the PI3K/Akt/mTOR pathway to facilitate megakaryocyte differentiation and platelet production.

Tissue fibrosis is characterized by excessive production, deposition, and contraction of the extracellular matrix (ECM). The second messenger cAMP has antifibrotic effects in fibroblasts from several tissues, including cardiac fibroblasts (CFs). Increased cellular cAMP levels can prevent the transformation of CFs into profibrogenic myofibroblasts, a critical step that precedes increased ECM deposition and tissue fibrosis. Here we tested two hypotheses: 1) myofibroblasts have a decreased ability to accumulate cAMP in response to G protein-coupled receptor (GPCR) agonists, and 2) increasing cAMP will not only prevent, but also reverse, the myofibroblast phenotype. We found that myofibroblasts produce less cAMP in response to GPCR agonists or forskolin and have decreased expression of several adenylyl cyclase (AC) isoforms and increased expression of multiple cyclic nucleotide phosphodiesterases (PDEs). Furthermore, we found that forskolin-promoted increases in cAMP or N(6)-phenyladenosine-cAMP, a protein kinase A-selective analog, reverse the myofibroblast phenotype, as assessed by the expression of collagen Iα1, α-smooth muscle actin, plasminogen activator inhibitor-1, and cellular contractile abilities, all hallmarks of a fibrogenic state. These results indicate that: 1) altered expression of AC and PDE isoforms yield a decrease in cAMP concentrations of cardiac myofibroblasts (relative to CFs) that likely contributes to their profibrotic state, and 2) approaches to increase cAMP concentrations not only prevent fibroblast-to-myofibroblast transformation but also can reverse the profibrotic myofibroblastic phenotype. We conclude that therapeutic strategies designed to enhance cellular cAMP concentrations in CFs may provide a means to reverse excessive scar formation following injury and to treat cardiac fibrosis.

7,3′,4′-Trihydroxyisoflavone (7,3′,4′-THIF) is a metabolite of daidzein which is a representative isoflavone found in soybean. Recent studies suggested that 7,3′,4′-THIF exerts a hypopigmentary effect in B16F10 cells, however, its underlying molecular mechanisms and specific target protein remain unknown. Here, we found that 7,3′,4′-THIF, but not daidzein, inhibited α-melanocyte-stimulating hormone (MSH)-induced intracellular and extracellular melanin production in B16F10 cells by directly targeting melanocortin 1 receptor (MC1R). Western blot data showed that 7,3′,4′-THIF inhibited α-MSH-induced tyrosinase, tyrosinase-related protein-1 (TYRP-1), and tyrosinase-related protein-2 (TYRP-2) expressions through the inhibition of Microphthalmia-associated transcription factor (MITF) expression and cAMP response element-binding (CREB) phosphorylation. 7,3′,4′-THIF also inhibited α-MSH-induced dephosphorylation of AKT and phosphorylation of p38 and cAMP-dependent protein kinase (PKA). cAMP and Pull-down assays indicated that 7,3′,4′-THIF strongly inhibited forskolin-induced intracellular cAMP production and bound MC1R directly by competing with α-MSH. Moreover, 7,3′,4′-THIF inhibited α-MSH-induced intracellular melanin production in human epidermal melanocytes (HEMs). Collectively, these results demonstrate that 7,3′,4′-THIF targets MC1R, resulting in the suppression of melanin production, suggesting a protective role for 7,3′,4′-THIF against melanogenesis.

Cyclic dinucleotides (CDNs) are promising vaccine adjuvants inducing balanced, potent humoral, and cellular immune responses. How aging influences CDN efficacy is unclear. We examined the vaccine efficacy of 3′,5′-cyclic diguanylic acid (cyclic di-GMP, CDG), the founding member of CDNs, in 1-year-old (middle-aged) and 2-year-old (aged) C57BL/6J mice. We found that 1- and 2-year-old C57BL/6J mice are defective in CDG-induced memory T helper (Th)1 and Th17 responses and high-affinity serum immunoglobulin (Ig)G, mucosal IgA production. Next, we generated two novel tumor necrosis factor (TNF) fusion proteins that target soluble TNF (solTNF) and transmembrane TNF (tmTNF) to monocyte-derived dendritic cells (moDCs) to enhance CDG vaccine efficacy in 1- and 2-year-old mice. The moDC-targeting TNF fusion proteins restored CDG-induced memory Th1, Th17, and high-affinity IgG, IgA responses in the 1- and 2-year-old mice. Together, the data suggested that aging negatively impacts CDG vaccine adjuvanticity. MoDC-targeting TNF fusion proteins enhanced CDG adjuvanticity in the aging mice.

PDE4 isoenzymes are critical in the control of cAMP signaling in rodent cardiac myocytes. Ablation of PDE4 affects multiple key players in excitation–contraction coupling and predisposes mice to the development of heart failure. As little is known about PDE4 in human heart, we explored to what extent cardiac expression and functions of PDE4 are conserved between rodents and humans. We find considerable similarities including comparable amounts of PDE4 activity expressed, expression of the same PDE4 subtypes and splicing variants, anchoring of PDE4 to the same subcellular compartments and macromolecular signaling complexes, and downregulation of PDE4 activity and protein in heart failure. The major difference between the species is a fivefold higher amount of non-PDE4 activity in human hearts compared to rodents. As a consequence, the effect of PDE4 inactivation is different in rodents and humans. PDE4 inhibition leads to increased phosphorylation of virtually all PKA substrates in mouse cardiomyocytes, but increased phosphorylation of only a restricted number of proteins in human cardiomyocytes. Our findings suggest that PDE4s have a similar role in the local regulation of cAMP signaling in rodent and human heart. However, inhibition of PDE4 has ‘global’ effects on cAMP signaling only in rodent hearts, as PDE4 comprises a large fraction of the total cardiac PDE activity in rodents but not in humans. These differences may explain the distinct pharmacological effects of PDE4 inhibition in rodent and human hearts.

Pao-Hsien Huang,1 Chih-Hua Tseng,1 Chia-Yu Lin,2 Chiang-Wen Lee,3–5 Feng-Lin Yen2,6 1School of Pharmacy, 2Department of Fragrance and Cosmetic Science, College of Pharmacy, Kaohsiung Medical University, Kaohsiung, 3Research Center for Industry of Human Ecology, Chang Gung University of Science and Technology, Kweishan, Taoyuan, 4Department of Nursing, Division of Basic Medical Sciences, 5Chronic Diseases and Health Promotion Research Center, Chang Gung University of Science and Technology, Chia-Yi, 6Institute of Biomedical Sciences, National Sun Yat-Sen University, Kaohsiung, Taiwan, Republic of China Background: 7,3´,4´-Trihydroxyisoflavone (734THI), a secondary metabolite derived from daidzein in soybean, possesses several biological activities, including antioxidant, skin whitening and anti-atopic dermatitis properties, but the poor aqueous solubility of 734THI has limited its application in medicine and cosmetic industry.Methods: The aim of the present study was to improve the physicochemical properties of 734THI using planetary ball mill preparation under a solvent-free process to improve its solubility and anti-pollutant activity. Results: 734THI nanoparticle powder (734THIN) was successfully prepared by the planetary ball mill technique using polyvinylpyrrolidone K30 as the excipient. 734THIN effectively increased the aqueous solubility and cellular uptake of 734THI by improving its physicochemical properties, including particle size reduction, crystalline–amorphous transformation and intermolecular hydrogen bonding with polyvinylpyrrolidone K30. In addition, 734THIN inhibited the overexpression of COX-2 and MMP-9 by downregulating MAPK pathway signaling in particulate matter-exposed HaCaT keratinocytes, while raw 734THI in PBS with low aqueous solubility did not show any anti-inflammatory or antiaging activity.Conclusion: 734THIN may be used as an additive in anti-pollutant skin care products for preventing particulate matter-induced inflammation and aging in skin. Keywords: 7,3´,4´-trihydroxyisoflavone, nanoparticle, planetary ball mill, particulate matter, inflammation

AIM: To compare three kinds of fluorescent probes for in vitro labeling and in vivo tracking of endothelial progenitor cells (EPCs) in a mouse model of laser-induced retinal injury. METHODS: EPCs were isolated from human umbilical cord blood mononuclear cells and labeled with three different fluorescent probes: 5-(and-6)-carboxyfluorescein diacetate succinimidyl ester (CFSE), 1,1′-dilinoleyl-3,3,3′,3′-tetramethylindo-carbocyanine perchlorate linked acetylated low-density lipoprotein (DiI-AcLDL), and green fluorescent protein (GFP). The fluorescent intensity of EPCs was examined by confocal microscopy. Survival rate of labeled EPCs was calculated with trypan blue staining, and their adhesive capability was assessed. A mouse model of retinal injury was induced by laser, and EPCs were injected into the vitreous cavity. Frozen section and fluorescein angiography on flat-mounted retinal samples was employed to track the labeled EPCs in vivo. RESULTS: EPCs labeled with CFSE and DiI-AcLDL exhibited an intense green and red fluorescence at the beginning; the fluorescence intensity decreased gradually to 20.23% and 49.99% respectively, after 28d. On the contrary, the florescent intensity of GFP-labeled EPCs increased in a time-dependent manner. All labeled EPCs showed normal morphology and no significant change in survival and adhesive capability. In the mouse model, transplantation of EPCs showed a protective effect against retinal injury. EPCs labeled with CFSE and DiI-AcLDL were successfully tracked in mice during the development of retinal injury and repair; however, GFP-labeled EPCs were not detected in the laser-injured mouse retina. CONCLUSION: The three fluorescent markers used in this study have their own set of advantages and disadvantages. CFSE and DiI-AcLDL are suitable for short-term EPC-labeling, while GFP should be used for long-term labeling. The choice of fluorescent markers should be guided by the purpose of the study.

Cyclic dinucleotides (CDNs) are promising vaccine adjuvants inducing balanced, potent humoral, and cellular immune responses. How aging influences CDN efficacy is unclear. We examined the vaccine efficacy of 3′,5′-cyclic diguanylic acid (cyclic di-GMP, CDG), the founding member of CDNs, in 1-year-old (middle-aged) and 2-year-old (aged) C57BL/6J mice. We found that 1- and 2-year-old C57BL/6J mice are defective in CDG-induced memory T helper (Th)1 and Th17 responses and high-affinity serum immunoglobulin (Ig)G, mucosal IgA production. Next, we generated two novel tumor necrosis factor (TNF) fusion proteins that target soluble TNF (solTNF) and transmembrane TNF (tmTNF) to monocyte-derived dendritic cells (moDCs) to enhance CDG vaccine efficacy in 1- and 2-year-old mice. The moDC-targeting TNF fusion proteins restored CDG-induced memory Th1, Th17, and high-affinity IgG, IgA responses in the 1- and 2-year-old mice. Together, the data suggested that aging negatively impacts CDG vaccine adjuvanticity. MoDC-targeting TNF fusion proteins enhanced CDG adjuvanticity in the aging mice. [ABSTRACT FROM AUTHOR]

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Clearance of fibrin through proteolytic degradation is a critical step of matrix remodeling that contributes to tissue repair in a variety of pathological conditions, such as stroke, atherosclerosis, and pulmonary disease. However, the molecular mechanisms that regulate fibrin deposition are not known. Here, we report that the p75 neurotrophin receptor (p75(NTR)), a TNF receptor superfamily member up-regulated after tissue injury, blocks fibrinolysis by down-regulating the serine protease, tissue plasminogen activator (tPA), and up-regulating plasminogen activator inhibitor-1 (PAI-1). We have discovered a new mechanism in which phosphodiesterase PDE4A4/5 interacts with p75(NTR) to enhance cAMP degradation. The p75(NTR)-dependent down-regulation of cAMP results in a decrease in extracellular proteolytic activity. This mechanism is supported in vivo in p75(NTR)-deficient mice, which show increased proteolysis after sciatic nerve injury and lung fibrosis. Our results reveal a novel pathogenic mechanism by which p75(NTR) regulates degradation of cAMP and perpetuates scar formation after injury.

Multidrug resistance is reported to be related to the transmembrane transportation of chemotherapeutic drugs by adenosine triphosphate-binding cassette (ABC) transporters. ABC subfamily G member 2 (ABCG2) is a member of the ABC transporter superfamily proteins, which have been implicated as a key contributor to the development of multidrug resistance in cancers. A new epigallocatechin gallate derivative, Y6 was synthesized in our group. Our previous study revealed that Y6 increased the sensitivity of drug-resistant cells to doxorubicin, which was associated with down-regulation of P-glycoprotein expression. In this study, we further determine whether Y6 could reverse ABCG2-mediated multidrug resistance. Results showed that, at non-toxic concentrations, Y6 significantly sensitized drug-selected non-small cell lung cancer cell line NCI-H460/MX20 to substrate anticancer drugs mitoxantrone, SN-38, and topotecan, and also sensitized ABCG2-transfected cell line HEK293/ABCG2-482-R2 to mitoxantrone and SN-38. Further study demonstrated that Y6 significantly increased the accumulation of [3H]-mitoxantrone in NCI-H460/MX20 cells by inhibiting the transport activity of ABCG2, without altering the expression levels and the subcellular localization of ABCG2. Furthermore, Y6 stimulated the adenosine triphosphatase activity with a concentration-dependent pattern under 20 μM in membranes overexpressing ABCG2. In addition, Y6 exhibited a strong interaction with the human ABCG2 transporter protein. Our findings indicate that Y6 may potentially be a novel reversal agent in ABCG2-positive drug-resistant cancers.

Two novel 3D metal-organic frameworks [Cd 3 (bpbc)(μ 3 -OH)(H 2 O) 3 ]·H 2 O (1) and [Zn 2 Na (bpbc)(DMF) 1.5 (EtOH) 0.5 (H 2 O) 5 ]·0.5H 2 O (2) have been synthesized by using biphenyl-2, 4, 6, 3′, 5′-pentacarboxylic acid (H 5 bpbc) as the ligand under solvothermal/hydrothermal conditions. The complexes were characterized by elemental analysis, single-crystal X-ray diffraction (XRD), powder X-ray diffraction (PXRD), IR spectra and thermogravimetric analysis (TGA). Structural analysis revealed that complex 1 shows a (5, 10)-connected 3D network based on the [Cd 6 (COO) 10 (μ 3 -OH) 2 ] SBUs with unusual topology, while complex 2 exhibits a (3, 3, 6)-connected 3D framework. The structural difference between 1 and 2 indicated that the coordination fashion of bpbc5− and the kind of metal ions could play critical role in the construction of MOFs. In addition, new fluorescence emissions were observed for 1 and 2 , and the solid state luminescent properties were investigated. Two novel 3D fluorescence metal-organic frameworks [Cd 3 (bpbc)(μ 3 -OH)(H 2 O) 3 ]·H 2 O (1) and [Zn 2 Na (bpbc)(DMF) 1.5 (EtOH) 0.5 (H 2 O) 5 ]·0.5H 2 O (2) have been constructed by using the self-assembly of biphenyl-2, 4, 6, 3′, 5′-pentacarboxylic acid (H 5 bpbc) and Zn2+/Cd2+ ions. Unlabelled Image • Two novel 3D coordination polymers were prepared by the self-assembly of H 5 bpbc and Zn2+/Cd2+ ions. • (5, 10)-connected and (3, 3, 6)-connected 3D framework structures were obtained with the same organic ligand. • The fluorescence properties of complexes 1 and 2 were recorded and discussed. [ABSTRACT FROM AUTHOR]

Abstract In view of the urgent need of determining polychlorinated biphenyls in the environment, we developed a highly sensitive and selective photoelectrochemical (PEC) aptasensor for determination of 3,3′,4,4′-tetrachlorobiphenyl (PCB77) by immobilizing aptamer on N-doped TiO 2 nanotubes (N-doped TiO 2 NTs). To improve analytical performance of the PEC sensor, the complementary DNA functionalized CdS quantum dots (DNA-CdS QDs) were introduced onto N-doped TiO 2 NTs by hybridization. In addition of PCB77, owing to high affinity of aptamer to PCB77, PCB77-aptamer complexes were formed by being bound of PCB77 whilst DNA-CdS QDs were released from the sensing surface. The complexes with poor conductivity hindered the interfacial electron transfer, leading to the photocurrent decrease. The more important is the release of DNA-CdS QDs enhanced the photocurrent decrease, playing the role of signal amplification. The photocurrent change was utilized to detect PCB77 quantitatively. The PEC aptasensor exhibited excellent analytical performance for detection of PCB77 with wide linear range of 0.1–100 ng/L and a low detection limit of 0.1 ng/L. It manifested outstanding selectivity for PCB77 in control experiments by employing six interferents which had similar structure or coexisted with PCB77. Besides, the PEC aptasensor was used to detect the content of PBC77 in the environment. Highlights • A simple and novel PEC aptasensor based on N-doped TiO 2 NTs was design for detection of PCB77. • Through introducing DNA-CdS QDs on sensing interface, the photocurrent of the aptasensor was enhanced and the detection signal for PCB77 was amplified. • The PEC aptasensor exhibited excellent analytical performance with high sensitivity and selectivity for detection of PCB77. [ABSTRACT FROM AUTHOR]

Purpose: The paper tries to assess the protective effect of fisetin against •OH-induced DNAdamage, then to investigate the possible mechanism.Methods: The protective effect was evaluated based on the content of malondialdehyde(MDA). The possible mechanism was analyzed using various antioxidant methods in vitro,including •OH scavenging (deoxyribose degradation), •O2- scavenging (pyrogallolautoxidation), DPPH• scavenging, ABTS•+ scavenging, and Cu2+-reducing power assays.Results: Fisetin increased dose-dependently its protective percentages against •OH-inducedDNA damage (IC50 value =1535.00±29.60 μM). It also increased its radical-scavengingpercentages in a dose-dependent manner in various antioxidants assays. Its IC50 values in•OH scavenging, •O2- scavenging, DPPH• scavenging, ABTS•+ scavenging, and Cu2+-reducing power assays, were 47.41±4.50 μM, 34.05±0.87 μM, 9.69±0.53 μM, 2.43±0.14μM, and 1.49±0.16 μM, respectively.Conclusion: Fisetin can effectively protect DNA against •OH-induced oxidative damagepossibly via reactive oxygen species (ROS) scavenging approach, which is assumed to behydrogen atom (H•) and/or single electron (e) donation (HAT/SET) pathways. In the HATpathway, the 3’,4’-dihydroxyl moiety in B ring of fisetin is thought to play an importantrole, because it can be ultimately oxidized to a stable ortho-benzoquinone form.

Pao-Hsien Huang,1,* Stephen Chu-Sung Hu,2,3,* Chiang-Wen Lee,4,5 An-Chi Yeh,6 Chih-Hua Tseng,7 Feng-Lin Yen1,8,9 1Department of Fragrance and Cosmetic Science, College of Pharmacy, Kaohsiung Medical University, Kaohsiung, 2Department of Dermatology, College of Medicine, Kaohsiung Medical University, Kaohsiung, 3Department of Dermatology, Kaohsiung Medical University Hospital, Kaohsiung, 4Research Center for Industry of Human Ecology, Chang Gung University of Science and Technology, Kweishan, Taoyuan, 5Department of Nursing, Division of Basic Medical Sciences, Chang Gung University of Science and Technology, Chia-Yi, 6Department of Cosmetics and Fashion Styling, Cheng Shiu University, Kaohsiung, 7School of Pharmacy, College of Pharmacy, Kaohsiung Medical University, Kaohsiung, 8Lipid Science and Aging Research Center, Kaohsiung Medical University, Kaohsiung, 9Institute of Biomedical Sciences, National Sun Yat-Sen University, Kaohsiung, Taiwan *These authors contributed equally to this work Abstract: 7,3',4'-Trihydroxyisoflavone (734THIF) is a secondary metabolite of daidzein and has been recently found to possess antioxidant, melanin inhibition, and skin cancer chemopreventive activities. However, the poor water solubility of 734THIF impedes its absorption and skin penetration and, therefore, limits its pharmacological effects when applied topically to the skin. We seek to use the nanoprecipitation method to prepare optimal eudragit E100 (EE)–polyvinyl alcohol (PVA)-loaded 734THIF nanoparticles (734N) to improve its physicochemical properties and thereby increase its water solubility, skin penetration, and biological activities. EE–PVA-loaded 734THIF nanoparticles (734N) were prepared, and their morphology and particle size were evaluated using a particle size analyzer and by electron microscopy. The drug loading and encapsulation efficiencies and in vitro solubility were determined using high-performance liquid chromatography. Hydrogen-bond formation was evaluated by 1H-nuclear magnetic resonance and Fourier transform infrared spectroscopy, and crystalline-to-amorphous transformation was determined by differential scanning calorimetry and X-ray diffractometry. In vitro skin penetration was analyzed using fresh pig skin mounted on Franz diffusion cells, and cytotoxicity against human keratinocyte HaCaT cells was evaluated using the MTT assay. Antioxidant activity was determined by 2,2-diphenyl-1-picrylhydrazyl-free radical scavenging ability. EE–PVA-loaded 734THIF nanoparticles showed good drug loading and encapsulation efficiencies and were characterized by improved physicochemical properties, including reduction in particle size, amorphous transformation, and intermolecular hydrogen-bond formation. This is associated with increased water solubility and enhanced in vitro skin penetration, with no cytotoxicity toward HaCaT cells. In addition, 734THIF nanoparticles retained their antioxidant activity. In conclusion, 734THIF nanoparticles are characterized by improved physicochemical properties, increased water solubility, and enhanced skin penetration, and these may have potential use in the future as a topical delivery formulation for the treatment of skin diseases. Keywords: 7,3',4'-trihydroxyisoflavone, nanoparticles, water solubility, skin penetration, topical delivery

The inhibitory activity of 3, 5, 6, 7, 8, 3′, 4′-heptamethoxyflavone extracted from Citri Reticulatae Pericarpium on RBL-2H3 cells degranulation was done by two different methods. At low concentration, the values of inhibition obtained by modified method were much larger than that of the classical method. Spectroscopic measurements and molecular docking calculation were applied to study the mechanism. It was induced by interaction between flavonoid and immunoglobulin E. Compared with the interaction between antibody and receptor, the force was weak, the inhibitory effect on β-hexosaminidase release was strong, with some structural changes to the antibody. [ABSTRACT FROM AUTHOR]

In this paper, the intermediate and final reaction products of catalytic oxidation of inorganic sulfides in the presence of oxygen dissolved in the kerosene fraction and 3,3′,5,5′-tetra-tert-butyl-4,4′-stilbenequinone were investigated. The thiosulfate and sulfate are major products of the oxidation of sodium sulfide under these conditions. The intermediate and final products in the catalytic oxidation of sulfide sulfur do not affect the rate of its oxidation. The yield of catalytic oxidation products depends on the nature of the sulfide and on the pH of the solution. The catalytic cycle for sulfide oxidation in the presence of 3,3′,5,5′-tetra-tert-butyl-4,4′-stilbenequinone is shown. The role of 3,3′,5,5′-tetra-tert-butyl-4,4′-stilbenequinone is to create a new and a more effective way of electron transfer from the reducing agent (sulfide) to the oxidant (oxygen). [ABSTRACT FROM AUTHOR]

We previously reported that the subcutaneous administration of 3,5,6,7,8,30,40- heptamethoxyflavone (HMF), a citrus polymethoxyflavone, attenuated depressive-like behavior and increased the expression of brain-derived neurotrophic factor (BDNF) in the hippocampus of a corticosterone-induced depression-like mouse model. We herein demonstrated that (1) HMF was detectable in the brain 10 and 30 min after its oral administration, (2) orally administered HMF improved chronic unpredictable mild stress (CUMS)-induced pathological conditions, including body weight loss and depressive-like behavior, and CUMS-induced neurochemical changes, such as reduction in BDNF expression, decrease in neurogenesis, and decreased level of phosphorylated calcium-calmodulin-dependent protein kinase II in the hippocampus, and (3) these effects of HMF were inhibited by the pre-administration of U0126, a mitogen-activated protein (MAP) kinase inhibitor. These results suggest that orally administered HMF is beneficial for the upregulation of BDNF in the hippocampus via the extracellular signal-regulated kinase1/2 (ERK1/2)/MAP system, which may account for its antidepression effects. [ABSTRACT FROM AUTHOR]

Objective · To explore the correlation between variants located in 3' untranslated regions (3'UTR) of NOTCH1 and JAG1 genes and conotruncal heart defects (CTD). Methods · Six hundred CTD children without 22q11 deletion and three hundred healthy children were enrolled in this hospital-based case-control study. Variants located in the 3'UTR regions of NOTCH1 and JAG1 genes were detected by high-throughput sequencing. The accuracy of the variants were verified by PCR and Sanger sequencing. Online software PicTar, TargetScan and microRNA.org were used to make functional predictions. Results · One mutation and three SNPs were found in the 3'UTR of NOTCH1. Three mutations and six SNPs were found in the 3'UTR of JAG1. The genotypic distributions of two SNPs (rs3840074 and rs8708) located in JAG1 3'UTR between CTD group and the controls were statistically significant (both P<0.05). Results of prediction showed that all the four mutations and two meaningful SNPs could bind to microRNA. Conclusion · The variants located in 3'UTR regions of NOTCH1 and JAG1 genes may be related to the occurrence of CTD. [ABSTRACT FROM AUTHOR]

A simple and green method for the synthesis of aurones by condensation of benzofuranone with aromatic aldehyde in neat water has been developed. The main advantages of this protocol include good yields, absence of catalyst, reagent, organic solvent, work-up and chromatographic purification. 4,5,3',4',5'-Pentamethoxy-6- hydroxyaurone, isolated from Smilax riparia was synthesized for the first time from 3-benzyloxy-4,5- dimethoxybenzaldehyde in five steps. [ABSTRACT FROM AUTHOR]

Prevention of ischemia-reperfusion liver injury is achieved by a combined omega-3 and thyroid hormone (T3) protocol, which may involve peroxisome-proliferator activated receptor-α (PPAR-α)-fibroblast growth factor 21 (FGF21) signaling supporting energy requirements. Combined docosahexaenoic acid (DHA; daily doses of 300 mg/kg for 3 days) plus 0.05 mg T3/kg given to fed rats elicited higher hepatic DHA contents and serum T3 levels, increased PPAR-α mRNA and its DNA binding, with higher mRNA expression of the PPAR-α target genes for carnitine-palmitoyl transferase 1α, acyl-CoA oxidase, and 3-hydroxyl-3-methylglutaryl-CoA synthase 2, effects that were mimicked by 0.1 mg T3/kg given alone or by the PPAR-α agonist WY-14632. Under these conditions, the mRNA expression of retinoic X receptor-α (RXR-α) is also increased, with concomitant elevation of the hepatic mRNA and protein FGF21 levels and those of serum FGF21. It is concluded that PPAR-α-FGF21 induction by DHA combined with T3 may involve ligand activation of PPAR-α by DHA and enhanced expression of PPAR-α by T3, with consequent upregulation of the FGF21 that is controlled by PPAR-α. Considering the beneficial effects of PPAR-α-FGF21 signaling on carbohydrate and lipid metabolism, further investigations are required to clarify its potential therapeutic applications in human metabolic disorders. © 2016 BioFactors, 42(6):638-646, 2016 [ABSTRACT FROM AUTHOR]

A series of imide resins were prepared using 2,3,3',4'-oxydiphthalic dianhydride, 4-phenylethynylphthalic anhydride, and aromatic diamines (1, 3-bis(3-aminophenoxy), 3,4'-oxyaniline, 2,2'-bis (trifluoromethyl) benzidine, and m-phenylenediamine) as starting materials. These imide oligomers were characterized by means of Fourier transform infrared spectroscopy, differential scanning calorimetry, intrinsic viscosity measurements, and rheological measurements. Some of these oligomers exhibited low (<1 Pa·s at 250°C) and stable (>2 h at 250°C) melt viscosity, which was highly desirable for resin transfer molding process. Thermosetting polyimides (PIs) were then produced from these oligomers via thermal cross-linking reaction of phenylethynyl group. The properties of the thermosets were studied using tensile and flexural testing, dynamic mechanical thermal analysis, and thermogravimetric analysis. The cured PIs exhibited a good combination of thermal and mechanical properties, with a tensile strength of 31-76 MPa, flexural strength of 38-142 MPa, glass transition temperatures of 233-358°C, and 5% weight loss temperatures of 540-545°C under nitrogen atmosphere. [ABSTRACT FROM AUTHOR]

We reported previously that hydroxylated polymethoxyflavones (HPMFs) effectively suppressed obesity in high-fat-induced mouse. In this study, we further investigated the molecular mechanism of action of 5-hydroxy-3,6,7,8,3',4'-hexamethoxyflavone (5-OH-HxMF), one of major HPMFs in orange peel. Treatment of 5-OH-HxMF effectively inhibited lipid accumulation by 55-60% in a dose-dependent manner. The 5-OH-HxMF attenuated adipogenesis through downregulating adipogenesis-related transcription factors such as peroxisome proliferator-activated receptor gamma (PPARc) and CCAAT/enhancer-binding proteins (C/EBPs), as well as downstream target fatty acid synthase and acetyl-CoA carboxylase (ACC). 5-OH-HxMF activated adenosine monophosphate-activated protein kinase signaling and silent mating type information regulation 1 (SIRTUIN 1 or SIRT1) in 3T3-L1 adipocytes to decrease lipid accumulation. In addition, the inhibition rate of lipid accumulation was compared between 5-OH-HxMF and 3,5,6,7,8,3',4'-heptamethoxyflavone (HpMF). 5-OH-HxMF inhibited lipid accumulation 15-20% more than HpMF did, indicating that hydroxyl group at position 5 can be a key factor in the suppression of adipogenesis. [ABSTRACT FROM AUTHOR]

ABSTRACT Tyrosinase is a binuclear copper-containing metalloprotein that leads the fast and regio-selective o-hydroxylation of monophenols to o-diphenols. However, the subsequent second oxidation to produce o-quinones, i.e., melanin precursors, from the o-diphenols has restricted its use to the production of functional o-diphenol derivatives. Herein, we present a combined strategy for the effective inhibition of melanin formation in tyrosinase reaction, which allows the use of tyrosinase as a monophenol monooxygenase. The o-diphenolic products were protected from being oxidized in the tyrosinase reaction by borate ions and L-ascorbic acid (LAA). Borate- o-diphenol complexes were favorable formed at high pH and consequentially protected the o-diphenolic products from the catecholase activity of tyrosinase. LAA not only directly reduced the byproduct, o-quinones, into o-diphenols but also assisted the completion of the tyrosinase reaction cycle by removing a hydroxyl group attached to the copper metal cluster at the active site of the met-form tyrosinase. The regio-selective o-hydroxylation of 7,4'-dihydroxyisoflavone (daidzein) to produce 7,3',4'-trihydroxyisoflavone (3'-ODI) was successfully carried out by whole E. coli cell biotransformation with heterologously expressed tyrosinase from Bacillus megaterium. The yield of this o-hydroxylation of 5 mM daidzein in one-pot 400 mL reaction was ca. 100% in 90 min and the productivity was 16.3 mg 3'-ODI · L−1 · h−1 · DCW mg−1, which is considerably higher than that of other monooxygenases. The method effectively abolished melanin synthesis, so that the o-diphenolic product remained stable without enzyme inactivation. Other monophenolic phytochemicals such as resveratrol and genistein could be subjected to the same strategy. After 1 h, 1 mM of genistein and resveratrol were both converted to orobol and piceatannol, respectively, with ca. 95% conversion yield. These results support the strong potential of tyrosinase as a monooxygenase for regio-selective o-hydroxylation of various monophenolic compounds. Biotechnol. Bioeng. 2016;113: 735-743. © 2015 Wiley Periodicals, Inc. [ABSTRACT FROM AUTHOR]

Chlorine is a principal disinfectant for food and environmental sanitation. Monitoring of free available chlorine (FAC) is essential for ensuring the efficacy of food disinfection processes that rely on chlorine. N,N-diethyl-pphenylenediamine (DPD) is commonly used for FAC monitoring. However, here, we show that upon contact with bovine serum albumin (BSA) or broiler carcasses, chlorite (HClO2)-based sanitizers acquire a pink colour, which can interfere with measurement of oxidized DPD absorbance at 513-550 nm. Alternatively, the pink colour did not interfere with 3,3',5,5'- tetramethylbenzidine (TMB)-based FAC monitoring. The FAC levels of NaClO and weakly acidified chlorous acid water (WACAW) were first adjusted by the TMB method and the killing activity of these sanitizers towards methicillinresistant Staphylococcus aureus (MRSA) and feline calicivirus (FCV) was compared in the presence or absence of 0.5% BSA. At 200 ppm FAC, NaClO lost its bactericidal activity against MRSA after 10-min incubation with 0.5% BSA. Meanwhile, under the same conditions WACAW reduced the number of bacteria to below the detection limit. Similar results were obtained with FCV, indicating that the chlorite-based WACAW sanitizer is relatively stable under organicmatter- rich conditions. Moreover, TMB is suitable for in situ FAC monitoring of chlorite-based sanitizers in food and environmental disinfection processes. [ABSTRACT FROM AUTHOR]

The kinetics and efficiency of 3,3',4,4'-tetrachlorobiphenyl (PCB77) degradation in aqueous solution by hybrid Feo/Fe3O4 nanoparticle system were investigated. The results showed that nano-sized Feo and Fe3O4 could efficiently degrade PCB77, and the residual rate of PCB77 by nano-sized Feo and Fe3O4 were 67.70% ± 0.42% and 82.26% ± 2.96%, respectively after 240 min of reaction (for 5 mg.L-1 PCB77 and 5 g.L-1 nanoparticles). The combined use of nanoscale Feo and Fe3O4 could enhance the degradation of PCB77. The dose ratios of nanosized Feo and Fe3O4 significantly affected the PCB77 degradation rate. At Feo/Fe3O4 ratios of 1:0.1, 1:0.2 and 1:1, the residual rates of PCB77 were 6.46%, 10.23% and 38.20%, respectively. The PCB77 degradation efficiency was also greatly affected by solution pH, and was maximised at pH 6.8. The degradation of PCB77 by Feo/Fe3O4 nanoparticle was a dechlorination process, and the chlorion concentration increased with the decreasing residual rate of PCB77 accordingly. Fe3O4 provided Fe2C and Fe3C for enhancing the PCB77 degradation by nanoscale Feo, suggesting a synergy between Feo and Fe3O4. [ABSTRACT FROM AUTHOR]

Two flavonoid compounds, 5,7,3',4'-tetrahydroxy-6-geranylflavonol (1) and kaempferol 7-O-ß-glucose (2) have been isolated from the leaves of Macaranga hispida (Blume), Mull.Arg. Isolation and purification were conducted by chromatography methods and chemical structure characterization was carried out by spectroscopic methods. The 5,7,3',4'-tetrahydrxyi-6-geranyl flavonol (1) and kaempferol 7-O-glucose (2) had moderate cytotoxic activity against murine leukemia P-388 cell lines with IC50 value of 0.22 and 101.5 μg/mL, respectively. The IC50 for antioxidant activities of (1) and (2) were 2.83 and 13.95 μg/mL, respectively. The LC50 of (1) and (2) from BSLT were 350 and >1000 μg/mL, respectively. [ABSTRACT FROM AUTHOR]

A new class of chemosensors based on the 1′,3,3′,4-tetrahydrospiro[chromene-2,2′-indole] ring system, which detects cyanide with high specificity, is described. These chemosensors show a distinct color change when treated with cyanide in acetonitrile solution buffered with sodium phosphate, and this procedure is not affected by the presence of other common anions. The chemisensors exhibit high sensitivity to low concentrations of cyanide, meeting the European Union water quality control criterion of sensitivity below 0.05 mg L−1, and show a very fast response within tens of seconds. The mechanism for detection is rationalized by the nucleophilic substitution of the phenolic oxygen atom at the indoline C-2 atom by the cyanide anion to form a stable indolylnitrile adduct and to generate the colored 4-nitrophenolate chromophore. These chemosensors can be synthesized by a simple procedure from commercially available starting materials. [ABSTRACT FROM AUTHOR]

Hydrothermal reactions of biphenyl-2,3,3′,5′-tetracarboxylic acid (H4bptc) with zinc salts in the presence of 1,4-bis(2-pyridylmethyl)piperazin (bpmp) and 4,4-dipyridyl (dpy) afforded the coordination polymers {[Zn2(bptc)(bpmp)] ·3H2O} n ( 1) and {[Zn(H2bptc)(dpy)] ·3H2O} n ( 2). Their structures were determined by single-crystal X-ray diffraction analysis and further characterized by elemental analysis, IR spectroscopy, and TG analyses. Complex 1 displays an unusual three-dimensional (3D) supramolecular motif generated by hydrogen bonding interactions between two single-layered 2D networks. Complex 2 represents a 2D layer structure, and such layers are further united together into three-dimensional supramolecular structure through intricate hydrogen bonding. In addition, luminescence properties of complexes 1 and 2 were also investigated. [ABSTRACT FROM AUTHOR]

Background: Pseudomonas aeruginosa is an opportunistic pathogen that exploits damaged epithelia to cause infection. Type IV pili (tfp) are polarly located filamentous structures which are the major adhesins for attachment of P. aeruginosa to epithelial cells. The extension and retraction of tfp powers a mode of surface translocation termed twitching motility that is involved in biofilm development and also mediates the active expansion of biofilms across surfaces. Extracellular adenosine triphosphate (eATP) is a key "danger" signalling molecule that is released by damaged epithelial cells to alert the immune system to the potential presence of pathogens. As P. aeruginosa has a propensity for infecting damaged epithelial tissues we have explored the influence of eATP on tfp biogenesis and twitching motility-mediated biofilm expansion by P. aeruginosa. Results: In this study we have found that eATP inhibits P. aeruginosa twitching motility-mediated expansion of interstitial biofilms at levels that are not inhibitory to growth. We have determined that eATP does not inhibit expression of the tfp major subunit, PilA, but reduces the levels of surface assembled tfp. We have also determined that the active twitching zone of expanding P. aeruginosa interstitial biofilms contain large quantities of eATP which may serve as a signalling molecule to co-ordinate cell movements in the expanding biofilm. The inhibition of twitching motility-mediated interstitial biofilm expansion requires eATP hydrolysis and does not appear to be mediated by the Chp chemosensory system. Conclusions: Endogenous eATP produced by P. aeruginosa serves as a signalling molecule to co-ordinate complex multicellular behaviours of this pathogen. Given the propensity for P. aeruginosa to infect damaged epithelial tissues, our observations suggest that eATP released by damaged cells may provide a cue to reduce twitching motility of P. aeruginosa in order to establish infection at the site of damage. Furthermore, eATP produced by P. aeruginosa biofilms and by damaged epithelial cells may play a role in P. aeruginosa pathogenesis by inducing inflammatory damage and fibrosis. Our findings have significant implications in the development and pathogenesis of P. aeruginosa biofilm infections. [ABSTRACT FROM AUTHOR]