Mechanism of triclosan inhibition of bacterial fatty acid synthesis

Triclosan is a broad-spectrum antibacterial agent that inhibits bacterial fatty acid synthesis at the enoyl-acyl carrier protein reductase (FabI) step. Resistance to triclosan in Escherichia coli is acquired through a missense mutation in the fabI gene that leads to the expression of FabI[G93V]. The specific activity and substrate affinities of FabI[G93V] are similar to FabI. Two different binding assays establish that triclosan dramatically increases the affinity of FabI for NAD+. In contrast, triclosan does not increase the binding of NAD+ to FabI[G93V]. The x-ray crystal structure of the FabI-NAD+-triclosan complex confirms that hydrogen bonds and hydrophobic interactions between triclosan and both the protein and the NAD+ cofactor contribute to the formation of a stable ternary complex, with the drug binding at the enoyl substrate site. These data show that the formation of a noncovalent "bi-substrate" complex accounts for the effectiveness of triclosan as a FabI inhibitor and illustrates that mutations in the FabI active site that interfere with the formation of a stable FabI-NAD+-triclosan ternary complex acquire resistance to the drug.

Human immunodeficiency virus type 1 subtypes differ in disease progression

At least 10 different genetic human immunodeficiency virus type 1 (HIV-1) subtypes (A-J) are responsible for the AIDS pandemic. Much of the understanding of HIV-1 disease progression derives from studies in the developed world where HIV infection is almost exclusively subtype B. This has led many to question whether the properties and consequences of HIV-1 infection can be generalized across subtypes that afflict the majority of infected persons in the developing world. From 1985 to 1997, a prospective study of registered female sex workers in Senegal tracked the introduction and spread of HIV-1 subtypes A, C, D, and G. In clinical follow-up, the AIDS-free survival curves differed by HIV-1 subtype. Women infected with a non-A subtype were 8 times more likely to develop AIDS than were those infected with subtype A (hazard ratio=8.23; P=. 009), the predominant subtype in the study. These data suggest that HIV-1 subtypes may differ in rates of progression to AIDS.

Pyrido[2,3-d]pyrimidin-7-one inhibitors of cyclin-dependent kinases

The identification of 8-ethyl-2-phenylamino-8H-pyrido[2, 3-d]pyrimidin-7-one (1) as an inhibitor of Cdk4 led to the initiation of a program to evaluate related pyrido[2, 3-d]pyrimidin-7-ones for inhibition of cyclin-dependent kinases (Cdks). Analysis of more than 60 analogues has identified some clear SAR trends that may be exploited in the design of more potent Cdk inhibitors. The most potent Cdk4 inhibitors reported in this study inhibit Cdk4 with IC(50) = 0.004 microM ([ATP] = 25 microM). X-ray crystallographic analysis of representative compounds bound to the related kinase, Cdk2, reveals that they occupy the ATP binding site. Modest selectivity between Cdks is exhibited by some compounds, and Cdk4-selective inhibitors block pRb(+) cells in the G(1)-phase of the cell division cycle.

Paeoniflorin abrogates DSS-induced colitis via a TLR4-dependent pathway

Paeonia lactiflora Pall is one of the most well-known herbs in China, Korea, and Japan for more than 1,200 years. Paeoniflorin, the major bioactive component of peony root, has recently been reported to have anticolitic activity. However, the underlying molecular mechanism is unclear. The present study was to explore the possible mechanism of paeoniflorin in attenuating dextran sulfate sodium (DSS)-induced colitis. Pre- and coadministration of paeoniflorin significantly reduced the severity of colitis and resulted in downregulation of several inflammatory parameters in the colon, including the activity of myeloperoxidase (MPO), the levels of TNF-α and IL-6, and the mRNA expression of proinflammatory mediators (MCP-1, Cox2, IFN-γ, TNF-α, IL-6, and IL-17). The decline in the activation of NF-κB p65, ERK, JNK, and p38 MAPK correlated with a decrease in mucosal Toll-like receptor 4 (TLR4) but not TLR2 or TLR5 expression. In accordance with the in vivo results, paeoniflorin downregulated TLR4 expression, blocked nuclear translocation of NF-κB p65, and reduced the production of IL-6 in LPS-stimulated mouse macrophage RAW264.7 cells. Transient transfection assay performed in LPS-stimulated human colon cancer HT-29 cells indicated that paeoniflorin inhibits NF-κB transcriptional activity in a dose-dependent manner. TLR4 knockdown and overexpression experiments demonstrated a requirement for TLR4 in paeoniflorin-mediated downregulation of inflammatory cytokines. Thus, for the first time, the present study indicates that paeoniflorin abrogates DSS-induced colitis via decreasing the expression of TLR4 and suppressing the activation of NF-κB and MAPK pathways.

Mechanism of enolase: the crystal structure of asymmetric dimer enolase-2-phospho-D-glycerate/enolase-phosphoenolpyruvate at 2.0 A resolution

Enolase, a glycolytic enzyme that catalyzes the dehydration of 2-phospho-d-glycerate (PGA) to form phosphoenolpyruvate (PEP), is a homodimer in all eukaryotes and many prokaryotes. Here, we report the crystal structure of a complex between yeast enolase and an equilibrium mixture of PGA and PEP. The structure has been refined using 29 854 reflections with an F/sigma(F) of >/=3 to an R of 0.137 with average deviations of bond lengths and bond angles from ideal values of 0.013 A and 3.1 degrees , respectively. In this structure, the dimer constitutes the crystallographic asymmetric unit. The two subunits are similar, and their superposition gives a rms distance between Calpha atoms of 0.91 A. The exceptions to this are the catalytic loop Val153-Phe169 where the atomic positions in the two subunits differ by up to 4 A and the loop Ser250-Gln277, which follows the catalytic loop Val153-Phe169. In the first subunit, the imidazole side chain of His159 is in contact with the phosphate group of the substrate/product molecule; in the other it is separated by water molecules. A series of hydrogen bonds leading to a neighboring enolase dimer can be identified as being responsible for ordering and stabilization of the conformationally different subunits in the crystal lattice. The electron density present in the active site suggests that in the active site with the direct ligand-His159 hydrogen bond PGA is predominantly bound while in the active site where water molecules separate His159 from the ligand the binding of PEP dominates. The structure indicates that the water molecule hydrating carbon-3 of PEP in the PEP --> PGA reaction is activated by the carboxylates of Glu168 and Glu211. The crystals are unique because they have resolved two intermediates on the opposite sides of the transition state.

The molecular environment of the Na+ binding site of thrombin

When Na+ binds to thrombin, a conformational change is induced that renders the enzyme kinetically faster and more specific in the activation of fibrinogen. Two Na+ binding sites have here been identified crystallographically by exchanging Na+ with Rb+. One is intermolecular, found on the surface between two symmetry-related thrombin molecules. Since it is not present in thrombin crystal structures having different crystal systems, the other Na+ site is the functionally relevant one. The second site has octahedral coordination with the carbonyl oxygen atoms of Arg221A and Lys224 and four conserved water molecules. It is located near Asp189 of the S1 specificity site in an elongated solvent channel (8 x 18 A) formed by four antiparallel beta-strands between Cys182-Cys191 and Val213-Tyr228. This channel, extending from the active site to the opposite surface of the enzyme, was first noted in the hirudin-thrombin structure and contains about 20 conserved water molecules linked together by a hydrogen bonding network that connects to the main chain of thrombin. Although the antiparallel beta-strand interactions of the functional Na+ binding site are the same in prethrombin2, the loops between the strands are very different, so that Asp189 and Arg221A are not positioned properly for either substrate or Na+ binding in prethrombin2. A water molecule with octahedral coordination has also been identified in factor Xa at the topologically equivalent Na+ site position of thrombin. Since activated protein C shows enhanced activity with monovalant cation binding, the same position is probably utilized by Na+. Since thrombin crystals could not be grown in the absence of Na+, the cation was leached from Na(+)-bound thrombin crystals by diffusion/exchange. Although both Na+ and their coordinating water molecules were removed from the Na+ binding sites, the remainder of the thrombin structure was, unexpectedly, the same. The lack of an allosteric change is most likely attributable to crystal packing effects. Thus, the structure of the slow form remains to be established crystallographically.

Dissecting primate early post-implantation development using long-term in vitro embryo culture

The transition from peri-implantation to gastrulation in mammals entails the specification and organization of the lineage progenitors into a body plan. Technical and ethical challenges have limited understanding of the cellular and molecular mechanisms that underlie this transition. We established a culture system that enabled the development of cynomolgus monkey embryos in vitro for up to 20 days. Cultured embryos underwent key primate developmental stages, including lineage segregation, bilaminar disc formation, amniotic and yolk sac cavitation, and primordial germ cell–like cell (PGCLC) differentiation. Single-cell RNA-sequencing analysis revealed development trajectories of primitive endoderm, trophectoderm, epiblast lineages, and PGCLCs. Analysis of single-cell chromatin accessibility identified transcription factors specifying each cell type. Our results reveal critical developmental events and complex molecular mechanisms underlying nonhuman primate embryogenesis in the early postimplantation period, with possible relevance to human development.

Chrysin ameliorates chemically induced colitis in the mouse through modulation of a PXR/NF-κB signaling pathway

Targeted activation of pregnane X receptor (PXR) in recent years has become a therapeutic strategy for inflammatory bowel disease. Chrysin is a naturally occurring flavonoid with anti-inflammation activity. The current study investigated the role of chrysin as a putative mouse PXR agonist in preventing experimental colitis. Pre-administration of chrysin ameliorated inflammatory symptoms in mouse models of colitis (dextran sodium sulfate- and 2,4,6-trinitrobenzene sulfonic acid-induced) and resulted in down-regulation of nuclear transcription factor κB (NF-κB) target genes (inducible NO synthase, intercellular adhesion molecule-1, monocyte chemotactic protein-1, cyclooxygenase 2, tumor necrosis factor-α, and interleukin 6) in the colon mucosa. Chrysin inhibited the phosphorylation/degradation of inhibitor κBα (IκBα), which correlated with the decrease in the activity of myeloperoxidase and the levels of tumor necrosis factor-α and interleukin 6 in the colon. Consistent with the in vivo results, chrysin blocked lipopolysaccharide -stimulated nuclear translocation of NF-κB p65 in mouse macrophage RAW264.7. Furthermore, chrysin dose-dependently activated human/mouse PXR in reporter gene assays and up-regulated xenobiotic detoxification genes in the colon mucosa, but not in the liver. Silencing of PXR by RNA interference demonstrated necessity of PXR in mediating chrysin's ability to induce xenobiotic detoxification genes and NF-κB inactivation. The repression of NF-κB transcription activity by chrysin was confirmed by in vitro PXR transduction. These findings suggest that the effect of chrysin in preventing chemically induced colitis is mediated in large part by a PXR/NF-κB pathway. The data also suggest that chrysin or chrysin-like flavonoids could be further developed as intestine-specific PXR activators.

Targeted Therapy for Inflammatory Diseases with Mesenchymal Stem Cells and Their Derived Exosomes: From Basic to Clinics

Inflammation is a beneficial and physiological process, but there are a number of inflammatory diseases which have detrimental effects on the body. In addition, the drugs used to treat inflammation have toxic side effects when used over a long period of time. Mesenchymal stem cells (MSCs) are pluripotent stem cells that can be isolated from a variety of tissues and can be differentiate into diverse cell types under appropriate conditions. They also exhibit noteworthy anti-inflammatory properties, providing new options for the treatment of inflammatory diseases. The therapeutic potential of MSCs is currently being investigated for various inflammatory diseases, such as kidney injury, lung injury, osteoarthritis (OA), rheumatoid arthritis (RA), and inflammatory bowel disease (IBD). MSCs can perform multiple functions, including immunomodulation, homing, and differentiation, to enable damaged tissues to form a balanced inflammatory and regenerative microenvironment under severe inflammatory conditions. In addition, accumulated evidence indicates that exosomes from extracellular vesicles of MSCs (MSC-Exos) play an extraordinary role, mainly by transferring their components to recipient cells. In this review, we summarize the mechanism and clinical trials of MSCs and MSC-Exos in various inflammatory diseases in detail, with a view to contributing to the treatment of MSCs and MSC-Exos in inflammatory diseases.

A novel lncRNA, LUADT1, promotes lung adenocarcinoma proliferation via the epigenetic suppression of p27

Long noncoding RNAs (lncRNAs) are known to regulate the development and progression of various cancers. However, few lncRNAs have been well characterized in lung adenocarcinoma (LUAD). Here, we identified the expression profile of lncRNAs and protein-coding genes via microarrays analysis of paired LUAD tissues and adjacent non-tumor tissues from five female non-smokes with LUAD. A total of 498 lncRNAs and 1691 protein-coding genes were differentially expressed between LUAD tissues and paired adjacent normal tissues. A novel lncRNA, LUAD transcript 1 (LUADT1), which is highly expressed in LUAD and correlates with T stage, was characterized. Both in vitro and in vivo data showed that LUADT1 knockdown significantly inhibited proliferation of LUAD cells and induced cell cycle arrest at the G0–G1 phase. Further analysis indicated that LUADT1 may regulate cell cycle progression by epigenetically inhibiting the expression of p27. RNA immunoprecipitation and chromatin immunoprecipitation assays confirmed that LUADT1 binds to SUZ12, a core component of polycomb repressive complex 2, and mediates the trimethylation of H3K27 at the promoter region of p27. The negative correlation between LUADT1 and p27 expression was confirmed in LUAD tissue samples. These data suggested that a set of lncRNAs and protein-coding genes were differentially expressed in LUAD. LUADT1 is an oncogenic lncRNA that regulates LUAD progression, suggesting that dysregulated lncRNAs may serve as key regulatory factors in LUAD progression.

Hereditary haemorrhagic telangiectasia: mutation detection, test sensitivity and novel mutations

BACKGROUND

Hereditary haemorrhagic telangiectasia (HHT) is a genetic disorder present in 1 in 8000 people and associated with arteriovenous malformations. Genetic testing can identify individuals at risk of developing the disease and is a useful diagnostic tool.

OBJECTIVE

To present a strategy for mutation detection in families clinically diagnosed with HHT.

METHODS

An optimised strategy for detecting mutations that predispose to HHT is presented. The strategy includes quantitative multiplex polymerase chain reaction, sequence analysis, RNA analysis, validation of missense mutations by amino acid conservation analysis for the ENG (endoglin) and ACVRL1 (ALK1) genes, and analysis of an ACVRL1 protein structural model. If no causative ENG or ACVRL1 mutation is found, proband samples are referred for sequence analysis of MADH4 (associated with a combined syndrome of juvenile polyposis and HHT).

RESULTS

Data obtained over the past eight years were summarised and 16 novel mutations described. Mutations were identified in 155 of 194 families with a confirmed clinical diagnosis (80% sensitivity). Of 155 mutations identified, 94 were in ENG (61%), 58 in ACVRL1 (37%), and three in MADH4 (2%).

CONCLUSIONS

For most missense variants of ENG and ACVRL1 reported to date, study of amino acid conservation showed good concordance between prediction of altered protein function and disease occurrence. The 39 families (20%) yet to be resolved may carry ENG, ACVRL1, or MADH4 mutations too complex or difficult to detect, or mutations in genes yet to be identified.

Successful liver transplantation following medical management of portopulmonary hypertension: a single-center series

Severe portopulmonary hypertension (POPH) is an absolute contraindication to orthotopic liver transplantation (OLT). Vasodilators have been used, but the safety of subsequent transplantation and the reversibility of pulmonary hypertension after transplantation are uncertain. This study examined the feasibility and post-transplant effects of liver transplantation following medical control of POPH. Eight consecutive patients (three females and five males, ages 39-51) with POPH as their only contraindication to transplantation were treated with continuous intravenous epoprostenol. Liver transplantation was considered if the mean pulmonary artery pressure (PAM) was lowered to <35 mmHg. Epoprostenol 2-8 ng/kg/min successfully improved hemodynamics in seven of eight patients, usually within 6.5 months of initiating therapy. PAM declined from an average of 43-33 mmHg (p=0.03); mean pulmonary vascular resistance declined from 410 to 192 dyn s cm-5 (p=0.01) and cardiac output increased from 6.6 to 10 L/min (p=0.02). Six of the seven responders were actively listed for liver transplantation. Two died on the waiting list; the remaining four were transplanted and remain alive and well 9-18 months post-OLT-two without vasodilators, and two on oral medication. We conclude that pulmonary vasodilators permit safe liver transplantation in some cases, and that POPH may be reversible after transplantation.

The crystal structure and amino acid sequence of dehaloperoxidase from Amphitrite ornata indicate common ancestry with globins

The full-length, protein coding sequence for dehaloperoxidase was obtained using a reverse genetic approach and a cDNA library from marine worm Amphitrite ornata. The crystal structure of the dehaloperoxidase (DHP) was determined by the multiple isomorphous replacement method and was refined at 1.8-A resolution. The enzyme fold is that of the globin family and, together with the amino acid sequence information, indicates that the enzyme evolved from an ancient oxygen carrier. The peroxidase activity of DHP arose mainly through changes in the positions of the proximal and distal histidines relative to those seen in globins. The structure of a complex of DHP with 4-iodophenol is also reported, and it shows that in contrast to larger heme peroxidases DHP binds organic substrates in the distal cavity. The binding is facilitated by the histidine swinging in and out of the cavity. The modeled position of the oxygen atom bound to the heme suggests that the enzymatic reaction proceeds via direct attack of the oxygen atom on the carbon atom bound to the halogen atom.

γ-Aminobutyric acid (GABA) signalling in human pancreatic islets is altered in type 2 diabetes

AIMS/HYPOTHESIS

γ-Aminobutyric acid (GABA) is a signalling molecule in the interstitial space in pancreatic islets. We examined the expression and function of the GABA signalling system components in human pancreatic islets from normoglycaemic and type 2 diabetic individuals.

METHODS

Expression of GABA signalling system components was studied by microarray, quantitative PCR analysis, immunohistochemistry and patch-clamp experiments on cells in intact islets. Hormone release was measured from intact islets.

RESULTS

The GABA signalling system was compromised in islets from type 2 diabetic individuals, where the expression of the genes encoding the α1, α2, β2 and β3 GABA(A) channel subunits was downregulated. GABA originating within the islets evoked tonic currents in the cells. The currents were enhanced by pentobarbital and inhibited by the GABA(A) receptor antagonist, SR95531. The effects of SR95531 on hormone release revealed that activation of GABA(A) channels (GABA(A) receptors) decreased both insulin and glucagon secretion. The GABA(B) receptor antagonist, CPG55845, increased insulin release in islets (16.7 mmol/l glucose) from normoglycaemic and type 2 diabetic individuals.

CONCLUSIONS/INTERPRETATION

Interstitial GABA activates GABA(A) channels and GABA(B) receptors and effectively modulates hormone release in islets from type 2 diabetic and normoglycaemic individuals.

Persistence, adherence, and medication-taking behavior in women with postmenopausal osteoporosis receiving denosumab in routine practice in Germany, Austria, Greece, and Belgium: 12-month results from a European non-interventional study

Persistence with and adherence to osteoporosis therapy are critical for fracture reduction. This non-interventional study is evaluating medication-taking behavior of women with postmenopausal osteoporosis (PMO) receiving denosumab in Germany, Austria, Greece, and Belgium. Patients were representative of the PMO population and highly persistent with and adherent to denosumab at 12 months.

INTRODUCTION

Persistence with and adherence to osteoporosis therapy are important for optimal treatment efficacy, namely fracture reduction. This ongoing, non-interventional study will evaluate medication-taking behavior of women with postmenopausal osteoporosis (PMO) receiving denosumab in routine practice in four European countries.

METHODS

The study enrolled women who had been prescribed subcutaneous denosumab (60 mg every 6 months) in accordance with prescribing information and local guidelines. Persistence was defined as receiving the subsequent injection within 6 months + 8 weeks of the previous injection. Adherence was defined as receiving two consecutive injections within 6 months ± 4 weeks of each other. Medication coverage ratio (MCR) was calculated using the time a patient was covered with denosumab, as assessed from prescription records. Treatment was assigned prior to and independently of enrollment; outcomes are recorded during routine practice.

RESULTS

These planned 12-month interim analyses included data from 1500 patients from 141 sites. Mean age was 66.4-72.4 years, mean baseline total hip T-scores ranged from -2.0 to -2.1 and femoral neck T-scores from -2.2 to -2.6, and 30.7-62.1% of patients had prior osteoporotic fracture. Persistence was 87.0-95.3%, adherence 82.7-89.3%, and MCR 91.3-95.4%. In a univariate analysis, increased age, decreased mobility, and increased distance to the clinic were associated with significantly decreased persistence; parental history of hip fracture was associated with significantly increased persistence.

CONCLUSIONS

These data extend the real-world evidence regarding persistence with and adherence to denosumab, both of which are critical for favorable clinical outcomes, including fracture risk reduction.

Angiogenic growth factor messenger ribonucleic acids in uterine natural killer cells

Angiogenesis is essential for endometrial growth and repair, and disruption of this process may lead to common disorders of women, including menorrhagia and endometriosis. In pregnancy, failure of the endometrial spiral arterioles to undergo remodeling leads to preeclampsia. Here we report that in addition to vascular endothelial growth factor A (VEGF-A), human endometrium expresses messenger ribonucleic acids (mRNAs) encoding VEGF-C, placenta growth factor (PlGF), the angiopoietins, angiopoietin 1 (Ang1) and Ang2, and the receptors VEGFR-3 (Flt-4), Tie 1, and Tie 2. Levels of VEGF-C, PlGF, and Tie 2 changed during the menstrual cycle. Intense hybridization for VEGF-C and PlGF mRNAs was found in uterine nature killer cells in secretory phase endometrium and for Ang2 mRNA in the same cells in the late secretory phase. Interleukin-2 (IL-2) and IL-15 up-regulated VEGF-C, but not PlGF or Ang2, mRNA levels in isolated NK cells. Conditioned medium from decidual NK cells did not induce human umbilical vein endothelial cell apoptosis. These results indicate that human endometrium expresses a wide range of angiogenic growth factors and that uterine nature killer cells may play an important role in the abnormal endometrial angiogenesis that underlies a range of disorders affecting women.

Notoginsenoside Ft1 acts as a TGR5 agonist but FXR antagonist to alleviate high fat diet-induced obesity and insulin resistance in mice

Obesity and its associated complications are highly related to a current public health crisis around the world. A growing body of evidence has indicated that G-protein coupled bile acid (BA) receptor TGR5 (also known as Gpbar-1) is a potential drug target to treat obesity and associated metabolic disorders. We have identified notoginsenoside Ft1 (Ft1) from Panax notoginseng as an agonist of TGR5 in vitro. However, the pharmacological effects of Ft1 on diet-induced obese (DIO) mice and the underlying mechanisms are still elusive. Here we show that Ft1 (100 mg/100 diet) increased adipose lipolysis, promoted fat browning in inguinal adipose tissue and induced glucagon-like peptide-1 (GLP-1) secretion in the ileum of wild type but not Tgr5 -/- obese mice. In addition, Ft1 elevated serum free and taurine-conjugated bile acids (BAs) by antagonizing Fxr transcriptional activities in the ileum to activate Tgr5 in the adipose tissues. The metabolic benefits of Ft1 were abolished in Cyp27a1 -/- mice which have much lower BA levels. These results identify Ft1 as a single compound with opposite activities on two key BA receptors to alleviate high fat diet-induced obesity and insulin resistance in mice.

Structure of extracellular tissue factor complexed with factor VIIa inhibited with a BPTI mutant

The event that initiates the extrinsic pathway of blood coagulation is the association of coagulation factor VIIa (VIIa) with its cell-bound receptor, tissue factor (TF), exposed to blood circulation following tissue injury and/or vascular damage. The natural inhibitor of the TF.VIIa complex is the first Kunitz domain of tissue factor pathway inhibitor (TFPI-K1). The structure of TF. VIIa reversibly inhibited with a potent (Ki=0.4 nM) bovine pancreatic trypsin inhibitor (BPTI) mutant (5L15), a homolog of TFPI-K1, has been determined at 2.1 A resolution. When bound to TF, the four domain VIIa molecule assumes an extended conformation with its light chain wrapping around the framework of the two domain TF cofactor. The 5L15 inhibitor associates with the active site of VIIa similar to trypsin-bound BPTI, but makes several unique interactions near the perimeter of the site that are not observed in the latter. Most of the interactions are polar and involve mutated positions of 5L15. Of the eight rationally engineered mutations distinguishing 5L15 from BPTI, seven are involved in productive interactions stabilizing the enzyme-inhibitor association with four contributing contacts unique to the VIIa.5L15 complex. Two additional unique interactions are due to distinguishing residues in the VIIa sequence: a salt bridge between Arg20 of 5L15 and Asp60 of an insertion loop of VIIa, and a hydrogen bond between Tyr34O of the inhibitor and Lys192NZ of the enzyme. These interactions were used further to model binding of TFPI-K1 to VIIa and TFPI-K2 to factor Xa, the principal activation product of TF.VIIa. The structure of the ternary protein complex identifies the determinants important for binding within and near the active site of VIIa, and provides cogent information for addressing the manner in which substrates of VIIa are bound and hydrolyzed in blood coagulation. It should also provide guidance in structure-aided drug design for the discovery of potent and selective small molecule VIIa inhibitors.

Size Effect of Encaged Clusters on the Exohedral Chemistry of Endohedral Fullerenes: A Case Study on the Pyrrolidino Reaction of ScxGd3-xN@C80 (x = 0−3)

We report a combined experimental and theoretical investigation on the regiochemistry of a series of TNT endohedral fullerenes ScxGd3-xN@C80 (x = 0-3) in 1,3-dipolar cycloadditions, which demonstrates that the regioselectivity of the TNT-based endohedral fullerenes ScxGd3-xN@C80 (x = 0-3) in the exohedral cycloadditions depends remarkably on the size of the encaged cluster.

Notoginsenoside Ft1 Promotes Fibroblast Proliferation via PI3K/Akt/mTOR Signaling Pathway and Benefits Wound Healing in Genetically Diabetic Mice

Wound healing requires the essential participation of fibroblasts, which is impaired in diabetic foot ulcers (DFU). Notoginsenoside Ft1 (Ft1), a saponin from Panax notoginseng, can enhance platelet aggregation by activating signaling network mediated through P2Y12 and induce proliferation, migration, and tube formation in cultured human umbilical vein endothelial cells. However, whether it can accelerate fibroblast proliferation and benefit wound healing, especially DFU, has not been elucidated. In the present study on human dermal fibroblast HDF-a, Ft1 increased cell proliferation and collagen production via PI3K/Akt/mTOR signaling pathway. On the excisional wound splinting model established on db/db diabetic mouse, topical application of Ft1 significantly shortened the wound closure time by 5.1 days in contrast with phosphate-buffered saline (PBS) treatment (15.8 versus 20.9 days). Meanwhile, Ft1 increased the rate of re-epithelialization and the amount of granulation tissue at day 7 and day 14. The molecule also enhanced mRNA expressions of COL1A1, COL3A1, transforming growth factor (TGF)-β1 and TGF-β3 and fibronectin, the genes that contributed to collagen expression, fibroblast proliferation, and consequent scar formation. Moreover, Ft1 facilitated the neovascularization accompanied with elevated vascular endothelial growth factor, platelet-derived growth factor, and fibroblast growth factor at either mRNA or protein levels and alleviated the inflammation of infiltrated monocytes indicated by reduced tumor necrosis factor-α and interleukin-6 mRNA expressions in the diabetic wounds. Altogether, these results indicated that Ft1 might accelerate diabetic wound healing by orchestrating multiple processes, including promoting fibroblast proliferation, enhancing angiogenesis, and attenuating inflammatory response, which provided a great potential application of it in clinics for patients with DFU.

Inhibition of the CDK2 and Cyclin A complex leads to autophagic degradation of CDK2 in cancer cells

Cyclin-dependent kinase 2 (CDK2) complex is significantly over-activated in many cancers. While it makes CDK2 an attractive target for cancer therapy, most inhibitors against CDK2 are ATP competitors that are either nonspecific or highly toxic, and typically fail clinical trials. One alternative approach is to develop non-ATP competitive inhibitors; they disrupt interactions between CDK2 and either its partners or substrates, resulting in specific inhibition of CDK2 activities. In this report, we identify two potential druggable pockets located in the protein-protein interaction interface (PPI) between CDK2 and Cyclin A. To target the potential druggable pockets, we perform a LIVS in silico screening of a library containing 1925 FDA approved drugs. Using this approach, homoharringtonine (HHT) shows high affinity to the PPI and strongly disrupts the interaction between CDK2 and cyclins. Further, we demonstrate that HHT induces autophagic degradation of the CDK2 protein via tripartite motif 21 (Trim21) in cancer cells, which is confirmed in a leukemia mouse model and in human primary leukemia cells. These results thus identify an autophagic degradation mechanism of CDK2 protein and provide a potential avenue towards treating CDK2-dependent cancers.

CDK2 can drive the proliferation of cancer cells. Here, the authors screened for a non-ATP competitive inhibitor of the CDK2/cylinA complex and find that Homoharringtonine can disrupt the complex and promote the degradation of CDK2.

C80 Encaging Four Different Atoms: The Synthesis, Isolation, and Characterizations of ScYErN@C80

The synthesis, isolation, and spectroscopic characterizations of an endohedral fullerene with four heteroatoms encapsulated (ScYErN@C80) are reported for the first time. The isomeric structure and electronic properties of this molecule are studied by various spectrometry methods such as high-performance liquid chromatography (HPLC), laser desorption time-of-flight (LD-TOF) mass spectroscopy, cyclic voltammetry, Fourier transform infrared (FTIR) spectroscopy, and visible-near infrared (vis-NIR) absorption spectroscopy. The carbon cage of ScYErN@C80 is assigned as Ih-C80, and the four-membered ScYErN cluster is suggested to rotate rapidly inside the fullerene cage. Six electrons are transferred from the nuclear cluster ScYErN to the fullerene cage, which leads to a closed-shell electronic structure of the Ih-C80 and results in excellent stability of this molecule.

Radiofrequency ablation for selective reduction in complex monochorionic pregnancies

Monochorionic pregnancies present unique challenges for selective fetal reduction, as vaso-occlusive procedures are required to ablate blood flow, usually in the umbilical cord, to achieve asystole in the selected fetus. We describe a case series of 35 monochorionic pregnancies (27 twins and eight triplets) undergoing selective fetal reduction using radiofrequency ablation. All procedures were performed under local anaesthesia. The procedure was technically successful in all cases. The live born rate was 88.6%. One (2.9%) woman miscarried within 2 weeks of the procedure, and two (5.7%) babies were stillborn. The median gestation at delivery was 36 weeks of gestation (range 24-41 weeks). There were no maternal complications. The median gestational age at procedure was 17 + 3 weeks (range from 12 + 5 to 27 + 4 weeks). All women had antenatal magnetic resonance imaging (MRI) post procedure. There were two (5.7%) cases of abnormal brain imaging. Our experience suggests that radiofrequency ablation is a safe and effective procedure for fetal reduction in complicated monochorionic pregnancies.

Platelet P2Y₁₂ receptors are involved in the haemostatic effect of notoginsenoside Ft1, a saponin isolated from Panax notoginseng

BACKGROUND AND PURPOSE

Saponins isolated from Panax notoginseng (Burk.) F.H. Chen have been shown to relieve thrombogenesis and facilitate haemostasis. However, it is not known which saponin accounts for this haemostatic effect. Hence, in the present study we aimed to identify which saponins contribute to its haemostatic activity and to elucidate the possible underlying mechanisms.

EXPERIMENTAL APPROACH

Platelet aggregation was analysed using a platelet aggregometer. Prothrombin time, activated partial thromboplastin time and thrombin time were measured using a blood coagulation analyser, which was further corroborated with bleeding time and thrombotic assays. The interaction of notoginsenoside Ft1 with the platelet P2Y₁₂ receptor was determined by molecular docking analysis, cytosolic Ca(2+) and cAMP measurements, and phosphorylation of PI3K and Akt assays.

KEY RESULTS

Among the saponins examined, Ft1 was the most potent procoagulant and induced dose-dependent platelet aggregation. Ft1 reduced plasma coagulation indexes, decreased tail bleeding time and increased thrombogenesis. Moreover, it potentiated ADP-induced platelet aggregation and increased cytosolic Ca(2+) accumulation, effects that were attenuated by clopidogrel. Molecular docking analysis suggested that Ft1 binds to platelet P2Y₁₂ receptors. The increase in intracellular Ca(2+) evoked by Ft1 in HEK293 cells overexpressing P2Y₁₂ receptors could be blocked by ticagrelor. Ft1 also affected the production of cAMP and increased phosphorylation of PI3K and Akt downstream of P2Y₁₂ signalling pathways.

CONCLUSION AND IMPLICATIONS

Ft1 enhanced platelet aggregation by activating a signalling network mediated through P2Y₁₂ receptors. These novel findings may contribute to the effective utilization of this compound in the therapy of haematological disorders.