This study identified the novel gene UAP1 in rice. UAP1 is involved in early leaf senescence and defence responses.
Plant leaf senescence and defence responses are important biological processes, but the molecular mechanisms involved are not well understood. This study identified a new rice mutant, spotted leaf 29 (spl29). The SPL29 gene was identified by map-based cloning, and SPL29 was confirmed as UDP-N-acetylglucosamine pyrophosphorylase 1 (UAP1) by enzymatic analysis. The mutant spl29 lacks UAP activity. The biological phenotypes for which UAP is responsible have not previously been reported in plants. The spl29 mutant displayed early leaf senescence, confirmed by chlorophyll loss and photosystem II decline as physiological indicators, chloroplast degradation as a cellular characteristic, and both upregulation of senescence transcription factors and senescence-associated genes, and downregulation of photosynthesis-related genes, as molecular evidence. Defence responses were induced in the spl29 mutant, shown by enhanced resistance to bacterial blight inoculation and upregulation of defence response genes. Reactive oxygen species, including O2
– and H2O2, accumulated in spl29 plants; there was also increased malondialdehyde content. Enhanced superoxide dismutase activity combined with normal catalase activity in spl29 could be responsible for H2O2 accumulation. The plant hormones jasmonic acid and abscisic acid also accumulated in spl29 plants. ROS and plant hormones probably play important roles in early leaf senescence and defence responses in the spl29 mutant. Based on these findings, it is suggested that UAP1 is involved in regulating leaf senescence and defence responses in rice.
Defence responses; leaf senescence; reactive oxygen species (ROS); rice (Oryza sativa); SPL29; UDP-N-acetylglucosamine pyrophosphorylase 1 (UAP1).
Lung cancer is a worldwide health problem and a leading cause of cancer-related deaths. Silencing of potential tumor suppressor genes (TSGs) by aberrant promoter methylation is an early event in the initiation and development of cancer. Thus, methylated cancer type-specific TSGs in DNA can serve as useful biomarkers for early cancer detection. We have now developed a “Multiplex Methylation Specific PCR” (MMSP) assay for analysis of the methylation status of multiple potential TSGs by a single PCR reaction. This method will be useful for early diagnosis and treatment outcome studies of non-small cell lung cancer (NSCLC). Genome-wide CpG methylation and expression microarrays were performed on lung cancer tissues and matched distant non-cancerous tissues from three NSCLC patients from China. Thirty-eight potential TSGs were selected and analyzed by methylation PCR on bisulfite treated DNA. On the basis of sensitivity and specificity, six marker genes, HOXA9, TBX5, PITX2, CALCA, RASSF1A, and DLEC1, were selected to establish the MMSP assay. This assay was then used to analyze lung cancer tissues and matched distant non-cancerous tissues from 70 patients with NSCLC, as well as 24 patients with benign pulmonary lesion as controls. The sensitivity of the assay was 99% (69/70). HOXA9 and TBX5 were the 2 most sensitive marker genes: 87% (61/70) and 84% (59/70), respectively. RASSF1A and DLEC1 showed the highest specificity at 99% (69/70). Using the criterion of identifying at least any two methylated marker genes, 61/70 cancer samples were positive, corresponding to a sensitivity of 87% and a specificity of 94%. Early stage I or II NSCLC could even be detected with a 100% specificity and 86% sensitivity. In conclusion, MMSP has the potential to be developed into a population-based screening tool and can be useful for early diagnosis of NSCLC. It might also be suitable for monitoring treatment outcome and recurrence.
Lung cancer; NSCLC; DNA methylation; PCR; Bisulfite treatment; Methylation microarray; Expression microarray; MMSP
Traditional micelle self-assembly is driven by the association of hydrophobic segments of amphiphilic molecules forming distinctive core-shell nanostructures in water. Here we report a surprising chaotropic anion-induced micellization of cationic ammonium-containing block copolymers. The resulting micelle nanoparticle consists of a large number of ion pairs (~60,000 in each hydrophobic core). Unlike chaotropic anions (e.g. ClO4−), kosmotropic anions (e.g. SO42−) were not able to induce micelle formation. A positive cooperativity was observed during micellization, where only a 3-fold change in ClO4− concentration was necessary for micelle formation, similar to our previously reported ultra-pH responsive behaviour. This unique ion pair-containing micelle provides a useful model system to study the complex interplay of non-covalent interactions (e.g. electrostatic, van der Waals and hydrophobic forces) during micelle self-assembly. This may lead to new fundamental insights and strategies for the future design of cooperative systems in molecular sensing and drug delivery applications.
micelle self-assembly; anti-Hofmeister effect; amphiphilic block copolymers; ion pairs
The enzymatic synthesis of 1,3-dioleoyl-2-palmitoylglycerol (OPO), one of the main components of human milk fats, has been hindered by the relatively high cost of sn-1,3-specific lipases and the deficiency in biocatalyst stability. The sn-1,3-specific lipase from Aspergillus oryzae (AOL) is highly and efficiently immobilized with the polystyrene-based hydrophobic resin D3520, with a significant 49.54-fold increase in specific lipase activity compared with the AOL powder in catalyzing the synthesis of OPO through the acidolysis between palm stearin and oleic acid (OA). The optimal immobilization conditions were investigated, including time course, initial protein concentration and solution pH. The sn-1,3 specificity of lipases under different immobilization conditions was evaluated and identified as positively associated with the lipase activity, and the pH of the immobilization solution influenced the regiospecificity and synthetic activity of these lipases. Immobilized AOL D3520, as the biocatalyst, was used for the enzymatic synthesis of the structured lipid OPO through the acidolysis between palm stearin and OA. The following conditions were optimized for the synthesis of structured lipid OPO: 65 °C temperature; 1:8 substrate molar ratio between palm stearin and OA; 8% (w/w) enzyme load; 3.5% water content of the immobilized lipase; and 1 h reaction time. Under these conditions, highly efficient C52 production (45.65%) was achieved, with a tripalmitin content of 2.75% and a sn-2 palmitic acid (PA) proportion of 55.08% in the system.
Febrile respiratory illness (FRI) results in substantial burden in semi-closed environments. Tackling risk factors may reduce transmission and infection. However, risk factors involved in one setting may not be generalizable in all settings due to differences in climate, residential environment, population genetic and cultural backgrounds. This study aims to identify risk factors of FRI and mono-viral infections in a tropical military environment.
From year 2009 to 2012, military personnel with temperature ≥37.5 °C, cough and/or sore throat, and personnel with no fever or no respiratory symptoms were recruited as cases and controls, respectively. Subjects provided nasal wash specimens and answered a standardized questionnaire. Resplex assays were used to determine the viral etiologies. Descriptive, univariate and multivariate analyses of the variables were performed using appropriate descriptive tests and logistic regression modelling, respectively, with R program.
A total of 7,743 FRI cases and 1,247 non-FRI study controls were recruited. Increasing age [adjusted odds ratio (AOR) = 1.03; 95 % confidence interval (CI) = 1.01-1.05], recruit camp (AOR = 4.67; 95 % CI = 3.99-5.46) and smoker (AOR = 1.31; 95 % CI = 1.13-1.52) were independent risk factors of FRI. Malay ethnicity was positively associated with influenza A(H1N1)pdm09 (AOR = 1.50; 95 % CI = 1.04-2.15) and coxsackie/echovirus (AOR = 1.67; 95 % CI = 1.19-2.36) mono-infection. Significant contact risk factors were stay-out personnel with ill household member (AOR = 4.96; 95 % CI = 3.39-7.24), and stay-in personnel with ill bunkmate and household member (AOR = 3.55; 95 % CI = 2.57-4.91). Staying in camp with none ill in bunk and at home was a protective factor against FRI (AOR = 0.80; 95 % CI = 0.64-0.99). These contact risk factors were similarly observed for the five most common viruses detected, namely adenovirus, rhinoviruses, influenza A and B, and coxsackie/echovirus.
Increasing age, smoker, recruit-camp, stay-out personnel with ill household members and stay-in personnel with ill bunkmates were independent risk factors of FRI in a semi-closed military environment. Early identification and isolation of ill personnel from their bunk may be effective to prevent and reduce transmission and disease burden.
Febrile respiratory infections; Risk factors; Military; Influenza A(H1N1)pdm09; Influenza B; Coxsackie/Echovirus; Adenovirus; Rhinovirus
Telomerase RNA (TER) is an essential component of the telomerase ribonucleoprotein complex. The mechanism for TER 3′-end processing is highly divergent among different organisms. Here we report a unique spliceosome-mediated TER 3′-end cleavage mechanism in Neurospora crassa which is distinct from that found specifically in the fission yeast Schizosaccharomyces pombe. While the S. pombe TER intron contains the canonical 5′-splice site GUAUGU, the N. crassa TER intron contains a non-canonical 5′-splice site AUAAGU that alone prevents the second step of splicing and promotes spliceosomal cleavage. The unique N. crassa TER 5′-splice site sequence is evolutionarily conserved in TERs from Pezizomycotina and early branching Taphrinomycotina species. This suggests that the widespread and basal N. crassa-type spliceosomal cleavage mechanism is more ancestral than the S. pombe-type. The discovery of a prevalent, yet distinct, spliceosomal cleavage mechanism throughout diverse fungal clades furthers our understanding of TER evolution and non-coding RNA processing.
Cardiac structural genes have been implicated as causative factors for congenital heart diseases (CHDs). NEXN is an F-actin binding protein and previously identified as a disease gene causing cardiomyopathies. Whether NEXN contributes to CHDs aetiologically remains unknown. Here, we explored the function of NEXN in cardiac development.
Methods and results
First, we determine the role of NEXN in cardiac differentiation using mouse P19cl6 in vitro model; we demonstrated that NEXN inhibited cardiac contractile markers, serving as a negative regulator. Interestingly, we found this effect was mediated by GATA4, a crucial transcription factor that controls cardiac development by knockdown, overexpression, and rescue experiment, respectively. We then generated transgenic mouse models and surprisingly, we discovered cardiac-selective expression of the NEXN gene caused atrial septal defects (ASDs). Next, to search for the mutations in NEXN gene in patients suffering from ASDs, we sequenced the exon and exon–intron joint regions of the NEXN gene in 150 probands with isolated ASDs and identified three mutations in the conserved region of NEXN (c.-52-78C>A, K199E, and L227S), which were not found in 500 healthy controls. Finally, we characterize the related mechanisms and found all mutations inhibited GATA4 expression.
We identify NEXN as a novel gene for ASD and its function to inhibit GATA4 established a critical regulation of an F-actin binding protein on a transcription factor in cardiac development.
Atrial septal defect; NEXN; GATA4; Actin; Mutation
Availability of diverse genomes makes it possible to predict gene function based on shared evolutionary history. This approach can be challenging, however, for pathways whose components do not exhibit a shared history, but rather, consist of distinct “evolutionary modules.” We introduce a computational algorithm, CLIME (clustering by inferred models of evolution), which inputs a eukaryotic species tree, homology matrix, and pathway (gene set) of interest. CLIME partitions the gene set into disjoint evolutionary modules, simultaneously learning the number of modules and a tree-based evolutionary history that defines each module. CLIME then expands each module by scanning the genome for new components that likely arose under the inferred evolutionary model. Application of CLIME to ∼1000 annotated human pathways, organelles and proteomes of yeast, red algae, and malaria, reveals unanticipated evolutionary modularity and novel, co-evolving components. CLIME is freely available and should become increasingly powerful with the growing wealth of eukaryotic genomes.
Due to their hypoimmunogenicity and unique immunosuppressive properties, mesenchymal stem cells (MSCs) are considered one of the most promising adult stem cell types for cell therapy. Although many studies have shown that MSCs exert therapeutic effects on several acute and subacute conditions, their long-term effects are not confirmed in chronic diseases. Immunogenicity is a major limitation for cell replacement therapy, and it is not well understood in vivo. We evaluated the immunogenicity of allogeneic MSCs in vivo by transplanting MSCs into normal and diabetic rats via the tail vein or pancreas and found that MSCs exhibited low immunogenicity in normal recipients and even exerted some immunosuppressive effects in diabetic rats during the initial phase. However, during the later stage in the pancreas group, MSCs expressed insulin and MHC II, eliciting a strong immune response in the pancreas. Simultaneously, the peripheral blood mononuclear cells in the recipients in the pancreas group were activated, and alloantibodies developed in vivo. Conversely, in the tail vein group, MSCs remained immunoprivileged and displayed immunosuppressive effects in vivo. These data indicate that different transplanting routes and microenvironments can lead to divergent immunogenicity of MSCs.
allogeneic mesenchymal stem cells; diabetes; immunogenicity; transplantation routes
Storm runoff events in the flooding season affect the water quality of reservoirs and increase risks to the water supply, but coping strategies have seldom been reported. The phenomenon of turbid current intrusion resulting in water turbidity and anoxic conditions reappearing after storm runoff, resulting in the deterioration of water quality, was observed in the flooding season in the deep canyon-shaped Heihe Reservoir. The objective of this work was to elucidate the effects of storm runoff on the Heihe Reservoir water quality and find a coping strategy. In this study, an intensive sampling campaign measuring water temperature, dissolved oxygen, turbidity, nutrients, and metals were conducted in the reservoir over a period of two years, and the water-lifting aerators were improved to achieve single aeration and a full layer of mixing and oxygenation functions using different volumes of gas. The operation of the improved water-lifting aerators mixed the reservoir three months ahead of the natural mixing time, and good water quality was maintained during the induced mixing period, thereby extending the good water quality period. The results can provide an effective coping strategy to improve the water quality of a source water reservoir and ensure the safety of drinking water.
rainstorm; reservoir; water quality; water-lifting aerator; mixing
Dicer, a ribonuclease III enzyme, is required for the maturation of microRNAs. To assess its role in cerebellar and medulloblastoma development, we genetically deleted Dicer in Nestin-positive neural progenitors and in mice lacking one copy for the Sonic Hedgehog receptor, Patched 1. We found that conditional loss of Dicer in mouse neural progenitors induced massive Trp53-independent apoptosis in all proliferative zones of the brain and decreased proliferation of cerebellar granule progenitors at embryonic day 15.5 leading to abnormal cerebellar development and perinatal lethality. Loss of one copy of Dicer significantly accelerated the formation of mouse medulloblastoma of the Sonic Hedgehog subgroup in Patched1-heterozygous mice. We conclude that Dicer is required for proper cerebellar development, and to restrain medulloblastoma formation.
In order to overcome the problems of poor understandability of the pattern recognition-based transient stability assessment (PRTSA) methods, a new rule extraction method based on extreme learning machine (ELM) and an improved Ant-miner (IAM) algorithm is presented in this paper. First, the basic principles of ELM and Ant-miner algorithm are respectively introduced. Then, based on the selected optimal feature subset, an example sample set is generated by the trained ELM-based PRTSA model. And finally, a set of classification rules are obtained by IAM algorithm to replace the original ELM network. The novelty of this proposal is that transient stability rules are extracted from an example sample set generated by the trained ELM-based transient stability assessment model by using IAM algorithm. The effectiveness of the proposed method is shown by the application results on the New England 39-bus power system and a practical power system — the southern power system of Hebei province.
how the protein environment modulates ligand pathways and
redox centers in the respiratory heme-copper oxidases is fundamental
for understanding the relationship between the structure and function
of these enzymes. In this study, we investigated the reactions of
O2 and NO with the fully reduced G232V mutant of ba3 cytochrome c oxidase from Thermus thermophilus (Tt ba3) in which a conserved glycine residue in the O2 channel
of the enzyme was replaced with a bulkier valine residue. Previous
studies of the homologous mutant of Rhodobacter sphaeroides
aa3 cytochrome c oxidase suggested
that the valine completely blocked the access of O2 to
the active site [Salomonsson, L., et al. (2004) Proc. Natl.
Acad. Sci. U.S.A. 101, 11617–11621]. Using photolabile
O2 and NO carriers, we find by using time-resolved optical
absorption spectroscopy that the rates of O2 and NO binding
are not significantly affected in the Tt ba3 G232V mutant. Classical molecular dynamics simulations of diffusion
of O2 to the active site in the wild-type enzyme and G232V
mutant show that the insertion of the larger valine residue in place
of the glycine appears to open up other O2 and NO exit/entrance
pathways that allow these ligands unhindered access to the active
site, thus compensating for the larger valine residue.
Trefoil factor 3 (TFF3), also called intestinal trefoil factor or Itf, is a 59 amino acid peptide found as a homodimer predominantly along the gastrointestinal tract and in serum. TFF3 expression is elevated during gastrointestinal adenoma progression and has been shown to promote mucosal wound healing. Here we show that in contrast to other trefoil factor family members, TFF1 and TFF2, TFF3 is highly expressed in mouse duodenum, jejunum and ileum and that its expression is regulated by food intake. Overexpression of TFF3 using a recombinant adeno-associated virus (AAV) vector, or daily administration of recombinant TFF3 protein in vivo improved glucose tolerance in a diet-induced obesity mouse model. Body weight, fasting insulin, triglyceride, cholesterol and leptin levels were not affected by TFF3 treatment. Induction of mucinous metaplasia was observed in mice with AAV-mediated TFF3 overexpression, however, no such adverse histological effect was seen after the administration of recombinant TFF3 protein. Altogether these results suggest that the therapeutic potential of targeting TFF3 to treat T2D may be limited.
Ovarian yolk sac tumors (YSTs) are rare neoplasms. No radiological study has been done to compare the imaging findings between this type of tumor and other ovarian tumors. Here we analyzed the CT findings of 11 pathologically proven ovarian YSTs and compared their imaging findings with 18 other types of ovarian tumors in the same age range. Patient age, tumor size, tumor shape, ascites and metastasis of two groups did not differ significantly (P > 0.05). A mixed solid-cystic nature, intratumoral hemorrhage, marked enhancement and dilated intratumoral vessel of two groups differed significantly (P < 0.05). The area under the ROC curve of four significant CT features was 0.679, 0.707, 0.705, and 1.000, respectively. Multivariate logistic regression analysis identified two independent signs of YST: intratumoral hemorrhage and marked enhancement. Our results show that certain suggestive CT signs that may be valuable for improving the accuracy of imaging diagnosis of YST and may be helpful in distinguishing YST from other ovarian tumors.
Cutaneous apocrine carcinoma (AC) is a rare adnexal neoplasm that histologically can mimic breast carcinoma metastatic to the skin or apocrine carcinoma arising in ectopic breast tissue. As extremely rare condition, neuroendocrine differentiation may be observed in AC although its etiology and pathogenesis is still unclear. We report here a case of unusual AC with neuroendocrine differentiation in right labium majus pudenda. A 43-year-old woman presented with a 6-month history of an asymptomatic pea-sized brownish nodule in right labium majus pudenda without enlargement of inguinal lymph nodes and bilateral breast nodules. The mass was totally resected. Microscopically, the tumor was solitary and located in the deep dermis without epidermal connection. Tumor cells were arranged in a micronodular or formed massive solid nests separated by densely fibroblastic stroma. Scattered glandular or rosette-like structures were identified within the tumor nodules. Immunohistochemically, the tumor cells were diffusely positive to CK7, CEA, GCDFP-15, synaptophysin, estrogen and progesterone receptors. Part of tumor cells expressed androgen receptor, but they were negative to CK20, CK5/6, p63 and S-100. Because of its rarity and histogenesis complexity, there exist diagnostic challenges for pathologists to differentiate cutaneous AC with neuroendocrine differentiation from other carcinomas with apocrine or neuroendocrine features. Our case demonstrates that the tumor shares some features with mammary carcinoma and might originate from mammary-like sweat gland in anogenital region. The results suggest that, for the first time, primary cutaneous AC with neuroendocrine differentiation may be analogous to the mammary neuroendocrine carcinoma with apocrine differentiation in histological feature and biological behavior.
Virtual Slides: The virtual slide(s) for this article can be found here: http://www.diagnosticpathology.diagnomx.eu/vs/7732276716685708.
Apocrine carcinoma; Neuroendocrine tumor; Neuroendocrine differentiation; Histogenesis; Differential diagnosis
α-Amylase as an important industrial enzyme has been widely used in starch processing, detergent, and paper industries. To improve expression efficiency of recombinant α-amylase from Bacillus licheniformis (B. licheniformis), the α-amylase gene from B. licheniformis was optimized according to the codon usage of Pichia pastoris (P. pastoris) and expressed in P. pastoris. Totally, the codons encoding 305 amino acids were optimized in which a total of 328 nucleotides were changed and the G+C content was increased from 47.6 to 49.2%. The recombinants were cultured in 96-deep-well microplates and screened by a new plate assay method. Compared with the wild-type gene, the optimized gene is expressed at a significantly higher level in P. pastoris after methanol induction for 168 h in 5- and 50-L bioreactor with the maximum activity of 8100 and 11000 U/mL, which was 2.31- and 2.62-fold higher than that by wild-type gene. The improved expression level makes the enzyme a good candidate for α-amylase production in industrial use.
Lysosomal degradation of cytoplasmic components by autophagy is essential for cellular survival and homeostasis under nutrient-deprived conditions1–4. Acute regulation of autophagy by nutrient-sensing kinases is well defined3, 5–7, but longer-term transcriptional regulation is relatively unknown. Here we show that the fed-state sensing nuclear receptor FXR8, 9 and the fasting transcriptional activator CREB10, 11 coordinately regulate the hepatic autophagy gene network. Pharmacological activation of FXR repressed many autophagy genes and inhibited autophagy even in fasted mice and feeding-mediated inhibition of macroautophagy was attenuated in FXR-knockout mice. From mouse liver ChIP-seq data12–15, FXR and CREB binding peaks were detected at 178 and 112, respectively, of 230 autophagy-related genes, and 78 genes showed shared binding, mostly in their promoter regions. CREB promoted lipophagy, autophagic degradation of lipids16, under nutrient-deprived conditions, and FXR inhibited this response. Mechanistically, CREB upregulated autophagy genes, including Atg7, Ulk1, and Tfeb, by recruiting the coactivator CRTC2. After feeding or pharmacological activation, FXR trans-repressed these genes by disrupting the functional CREB/CRTC2 complex. This study identifies the novel FXR/CREB axis as a key physiological switch regulating autophagy, resulting in sustained nutrient regulation of autophagy during feeding/fasting cycles.
Macrophages play pivotal roles in development, homeostasis, tissue repair and immunity. Macrophage proliferation is promoted by macrophage colony-stimulating factor (M-CSF)-induced Akt signaling; yet, how this process is terminated remains unclear. Here, we identify casein kinase 2-interacting protein-1 (CKIP-1) as a novel inhibitor of macrophage proliferation. In resting macrophages, CKIP-1 was phosphorylated at Serine 342 by constitutively active GSK3β, the downstream target of Akt. This phosphorylation triggers the polyubiquitination and proteasomal degradation of CKIP-1. Upon M-CSF stimulation, Akt is activated by CSF-1R-PI3K and then inactivates GSK3β, leading to the stabilization of CKIP-1 and β-catenin proteins. β-catenin promotes the expression of proliferation genes including cyclin D and c-Myc. CKIP-1 interacts with TRAF6, a ubiquitin ligase required for K63-linked ubiquitination and plasma membrane recruitment of Akt, and terminates TRAF6-mediated Akt activation. By this means, CKIP-1 inhibits macrophage proliferation specifically at the late stage after M-CSF stimulation. Furthermore, CKIP-1 deficiency results in increased proliferation and decreased apoptosis of macrophages in vitro and CKIP-1−/− mice spontaneously develop a macrophage-dominated splenomegaly and myeloproliferation. Together, these data demonstrate that CKIP-1 plays a critical role in the regulation of macrophage homeostasis by inhibiting TRAF6-mediated Akt activation.
macrophage proliferation; Akt signaling; TRAF6; GSK3β; CKIP-1
In this study, we present a microarray approach for the typing of influenza A and B viruses, and the subtyping of H1 and H3 subtypes. We designed four pairs of specific multiplex RT-PCR primers and eight specific oligonucleotide probes and prepared microarrays to identify the specific subtype of influenza virus. Through amplification and fluorescent marking of the multiplex RT-PCR products on the M gene of influenza A and B viruses and the HA gene of subtypes H1 and H3, the PCR products were hybridized with the microarray, and the results were analyzed using a microarray scanner. The results demonstrate that the chip developed by our research institute can detect influenza A and B viruses specifically and identify the subtypes H1 and H3 at a minimum concentration of 1 × 102 copies/μL of viral RNA. We tested 35 clinical samples and our results were identical to other fluorescent methods. The microarray approach developed in this study provides a reliable method for the monitoring and testing of seasonal influenza.
Influenza A virus; Influenza B virus; Typing; DNA microarray
The mycobacterial cell wall frequently has been used as a target for drug development, and d-glutamate, synthesized by glutamate racemase (MurI), is an important component of peptidoglycan. While the essentiality of the murI gene has been shown in several bacterial species, including Escherichia coli, Bacillus anthracis, and Streptococcus pneumoniae, studies in mycobacteria have not yet provided definitive results. This study aimed to determine whether murI is indeed essential and can serve as a possible target for structure-aided drug design. We have achieved this goal by creating a ΔmurI strain of Mycobacterium smegmatis, a close relative of Mycobacterium tuberculosis. The deletion of the murI gene in M. smegmatis could be achieved only in minimal medium supplemented with d-glutamate, demonstrating that MurI is essential for growth and that glutamate racemase is the only source of d-glutamate for peptidoglycan synthesis in M. smegmatis.
The first genome sequence of a group A Streptococcus pyogenes serotype M23 (emm23) strain (M23ND), isolated from an invasive human infection, has been completed. The genome of this opacity factor-negative (SOF−) strain is composed of a circular chromosome of 1,846,477 bp. Gene profiling showed that this strain contained six phage-encoded and 24 chromosomally inherited well-known virulence factors, as well as 11 pseudogenes. The bacterium has acquired four large prophage elements, ΦM23ND.1 to ΦM23ND.4, harboring genes encoding streptococcal superantigen (ssa), streptococcal pyrogenic exotoxins (speC, speH, and speI), and DNases (spd1 and spd3), with phage integrase genes being present at one flank of each phage insertion, suggesting that the phages were integrated by horizontal gene transfer. Comparative analyses revealed unique large-scale genomic rearrangements that result in genomic rearrangements that differ from those of previously sequenced GAS strains. These rearrangements resulted in an imbalanced genomic architecture and translocations of chromosomal virulence genes. The covS sensor in M23ND was identified as a pseudogene, resulting in the attenuation of speB function and increased expression of the genes for the chromosomal virulence factors multiple-gene activator (mga), M protein (emm23), C5a peptidase (scpA), fibronectin-binding proteins (sfbI and fbp54), streptolysin O (slo), hyaluronic acid capsule (hasA), streptokinase (ska), and DNases (spd and spd3), which were verified by PCR. These genes are responsible for facilitating host epithelial cell binding and and/or immune evasion, thus further contributing to the virulence of M23ND. In conclusion, strain M23ND has become highly pathogenic as the result of a combination of multiple genetic factors, particularly gene composition and mutations, prophage integrations, unique genomic rearrangements, and regulated expression of critical virulence factors.
Periprosthetic infection remains a challenging clinical complication. We investigated the antibacterial properties of pure (99.9%) magnesium (Mg) in vitro and in an in vivo rat model of implant-related infection. Mg was highly effective against methicillin-resistant Staphylococcus aureus-induced osteomyelitis and improved new peri-implant bone formation. Bacterial icaA and agr RNAIII transcription levels were also assessed to characterize the mechanism underlying the antibacterial properties of the Mg implant.
Plasma urotensin II (UII) has been observed to be raised in patients with acute myocardial infarction; suggesting a possible cardiac protective role for this peptide. However, the molecular mechanism is unclear. Here, we treated cultured cardiomyocytes with H2O2 to induce oxidative stress; observed the effect of UII on H2O2-induced apoptosis and explored potential mechanisms. UII pretreatment significantly reduced the number of apoptotic cardiomyocytes induced by H2O2; and it partly abolished the increase of pro-apoptotic protein Bax and the decrease of anti-apoptotic protein Bcl-2 in cardiomyocytes induced by H2O2. SiRNA targeted to the urotensin II receptor (UT) greatly inhibited these effects. Further analysis revealed that UII increased the production of hydrogen sulfide (H2S) and the level of cystathionine-γ-lyase (CSE) by activating the ERK signaling in H2O2-treated-cardiomyocytes. Si-CSE or ERK inhibitor not only greatly inhibited the increase in CSE level or the phosphorylation of ERK induced by UII but also reversed anti-apoptosis of UII in H2O2-treated-cadiomyocytes. In conclusion, UII rapidly promoted the phosphorylation of ERK and upregulated CSE level and H2S production, which in turn activated ERK signaling to protect cardiomyocytes from apoptosis under oxidative stress. These results suggest that increased plasma UII level may protect cardiomyocytes at the early-phase of acute myocardial infarction in patients.
urotensin II; apoptosis; cardiomyocyte; cystathionine-γ-lyase (CSE); hydrogen sulfide (H2S)
Mycoepoxydiene (MED) is a polyketide that can be isolated from a marine fungus and is associated with various activities, including antitumor and anti-inflammatory functions. However, its effects on atherosclerosis remain unknown. Macrophage-derived foam cells play crucial roles in the initiation and progression of atherosclerotic plaques. In this study, we investigated the effects of MED on oxidized low-density lipoprotein (ox-LDL)-induced macrophage foam cell formation and activation, and on high fat diet (HFD)-induced atherosclerosis in ApoE-deficient (ApoE−/−) mice.
Our findings show that MED could significantly inhibit ox-LDL-induced macrophage foam cell formation and suppress the expression of lectin-like oxidized low-density lipoprotein receptor-1 (LOX-1), which is a receptor for ox-LDL. Additionally, MED could significantly inhibit the secretion of proinflammatory cytokines, such as tumor necrosis factor (TNF-α), interleukin (IL)-6, and IL-1β. Mechanistically, MED inhibited NF-κB activation by blocking IκB-α degradation and reducing NF-κB DNA binding activity. Moreover, MED dramatically reduced the occurrence of HFD-induced atherosclerotic lesions in ApoE−/− mice.
Our study shows that MED can inhibit macrophage foam cell formation and activation by inhibiting NF-κB activation, thereby protecting ApoE−/− mice from HFD-induced atherosclerosis. Our findings suggest that MED might be a potential lead compound for the development of antiatherosclerotic therapeutics.
Electronic supplementary material
The online version of this article (doi:10.1186/s13578-015-0017-y) contains supplementary material, which is available to authorized users.
Mycoepoxydiene; ox-LDL; Macrophage; Foam cell; Atherosclerosis