Regulation of alternative splicing of Bcl-x by IL-6, GM-CSF and TPA

The splicing of many alternative exons in the precursor messenger RNA (pre-mRNA) is regulated by extracellular factors but the underlying molecular bases remain unclear. Here we report the differential regulation of Bcl-x pre-mRNA splicing by extracellular factors and their distinct requirements for pre-mRNA elements. In K562 leukemia cells, treatment with interleukin-6 (IL-6) or granulocyte-macrophage colony stimulating factor (GM-CSF) reduced the proportion of the Bcl-xL variant mRNA while treatment with 12-O-tetradecanoylphorbol 13-acetate (TPA) had no effect. In U251 glioma cells, however, TPA efficiently increased the Bcl-xL level. These regulations were also seen for a transfected splicing reporter mini-gene. Further analyses of deletion mutants indicate that nucleotides 1-176 of the downstream intron are required for the IL-6 effect, whereas additional nucleotides 177-284 are essential for the GM-CSF effect. As for the TPA effect, only nucleotides 1-76 are required in the downstream intron. Thus, IL-6, GM-CSF and TPA differentially regulate Bcl-x splicing and require specific intronic pre-mRNA sequences for their respective effects.     

Genome Sequence of Staphylococcus capitis QN1, Which Causes Infective Endocarditis

Staphylococcus capitis is a subtype of coagulase-negative staphylococci (CoNS) which could emerge as a significant pathogen causing infective endocarditis, prosthetic valve endocarditis, and late-onset sepsis. We isolated S. capitis strain QN1 from the skin swab sample of a female. Here we prepared a genome sequence for this strain consisting of 30 contigs totaling 2,430,101 bases and a GC content of 32.76%.     

Transcriptional suppression of nephrin in podocytes by macrophages: roles of inflammatory cytokines and involvement of the PI3K/Akt pathway

Expression of nephrin, a crucial component of the glomerular slit diaphragm, is downregulated in patients with proteinuric glomerular diseases. Using conditionally immortalized reporter podocytes, we found that bystander macrophages as well as macrophage-derived cytokines IL-1beta and TNF-alpha markedly suppressed activity of the nephrin gene promoter in podocytes. The cytokine-initiated repression was reversible, observed on both basal and inducible expression, independent of Wilms' tumor suppressor WT1, and caused in part via activation of the phosphatidylinositol-3-kinase/Akt pathway. These results indicated a novel mechanism by which activated macrophages participate in the induction of proteinuria in glomerular diseases.     

Selection for High Oridonin Yield in the Chinese Medicinal Plant Isodon (Lamiaceae) Using a Combined Phylogenetics and Population Genetics Approach

Oridonin is a diterpenoid with anti-cancer activity that occurs in the Chinese medicinal plant Isodon rubescens and some related species. While the bioactivity of oridonin has been well studied, the extent of natural variation in the production of this compound is poorly known. This study characterizes natural variation in oridonin production in order to guide selection of populations of Isodon with highest oridonin yield. Different populations of I. rubescens and related species were collected in China, and their offspring were grown in a greenhouse. Samples were examined for oridonin content, genotyped using 11 microsatellites, and representatives were sequenced for three phylogenetic markers (ITS, rps16, trnL-trnF). Oridonin production was mapped on a molecular phylogeny of the genus Isodon using samples from each population as well as previously published Genbank sequences. Oridonin has been reported in 12 out of 74 species of Isodon examined for diterpenoids, and the phylogeny indicates that oridonin production has arisen at least three times in the genus. Oridonin production was surprisingly consistent between wild-collected parents and greenhouse-grown offspring, despite evidence of gene flow between oridonin-producing and non-producing populations of Isodon. Additionally, microsatellite genetic distance between individuals was significantly correlated with chemical distance in both parents and offspring. Neither heritability nor correlation with genetic distance were significant when the comparison was restricted to only populations of I. rubescens, but this result should be corroborated using additional samples. Based on these results, future screening of Isodon populations for oridonin yield should initially prioritize a broad survey of all species known to produce oridonin, rather than focusing on multiple populations of one species, such as I. rubescens. Of the samples examined here, I. rubescens or I. japonicus from Henan province would provide the best source of oridonin.     

Mechanism of Na‐Ion Storage in Hard Carbon Anodes Revealed by Heteroatom Doping

Hard carbon is the leading candidate anode for commercialization of Na‐ion batteries. Hard carbon has a unique local atomic structure, which is composed of nanodomains of layered rumpled sheets that have short‐range local order resembling graphene within each layer, but complete disorder along the c‐axis between layers. A primary challenge holding back the development of Na‐ion batteries is that a complete understanding of the structure–capacity correlations of Na‐ion storage in hard carbon has remained elusive. This article presents two key discoveries: first, the characteristics of hard carbons structure can be modified systematically by heteroatom doping, and second, that these structural changes greatly affect Na‐ion storage properties, which reveals the mechanisms for Na storage in hard carbon. Specifically, via P or S doping, the interlayer spacing is dilated, which extends the low‐voltage plateau capacity, while increasing the defect concentrations with P or B doping leads to higher sloping sodiation capacity. The combined experimental studies and first principles calculations reveal that it is the Na‐ion‐defect binding that corresponds to the sloping capacity, while the Na intercalation between graphenic layers causes the low‐potential plateau capacity. The understanding suggests a new design principle of hard carbon anode: more reversibly binding defects and dilated turbostratic domains, given that the specific surface area is maintained low.     

In Situ TEM Study of Volume Expansion in Porous Carbon Nanofiber/Sulfur Cathodes with Exceptional High‐Rate Performance

Although lithium sulfur batteries (LSBs) have attracted much interest owing to their high energy densities, synthesis of high‐rate cathodes and understanding their volume expansion behavior still remain challenging. Herein, electrospinning is used to prepare porous carbon nanofiber (PCNF) hosts, where both the pore volume and surface area are tailored by optimizing the sacrificial agent content and the activation temperature. Benefiting from the ameliorating functional features of high electrical conductivity, large pore volume, and Li ion permselective micropores, the PCNF/A550/S electrode activated at 550 °C exhibits a high sulfur loading of 71 wt%, a high capacity of 945 mA h g^?1 at 1 C, and excellent high‐rate capability. The in situ transmission electron microscope examination reveals that the lithiation product, Li₂S, is contained within the electrode with only ≈35% volume expansion and the carbon host remains intact without fracture. In contrast, the PCNF/A750/S electrode with damaged carbon spheres exhibits sulfur sublimation, a larger volume expansion of over 61%, and overflowing of Li₂S, a testament to its poor cyclic stability. These findings provide, for the first time, a new insight into the correlation between volume expansion and electrochemical performance of the electrode, offering a potential design strategy to synthesize high‐rate and stable LSB cathodes.     

Redox regulation of plant stem cell fate

Despite the importance of stem cells in plant and animal development, the common mechanisms of stem cell maintenance in both systems have remained elusive. Recently, the importance of hydrogen peroxide (H₂O₂) signaling in priming stem cell differentiation has been extensively studied in animals. Here, we show that different forms of reactive oxygen species (ROS) have antagonistic roles in plant stem cell regulation, which were established by distinct spatiotemporal patterns of ROS‐metabolizing enzymes. The superoxide anion () is markedly enriched in stem cells to activate WUSCHEL and maintain stemness, whereas H₂O₂ is more abundant in the differentiating peripheral zone to promote stem cell differentiation. Moreover, H₂O₂ negatively regulates biosynthesis in stem cells, and increasing H₂O₂ levels or scavenging leads to the termination of stem cells. Our results provide a mechanistic framework for ROS‐mediated control of plant stem cell fate and demonstrate that the balance between and H₂O₂ is key to stem cell maintenance and differentiation.     

Rational redesign of the 4-chlorobenzoate binding site of 4-chlorobenzoate: coenzyme a ligase for expanded substrate range

Environmental aromatic acids are transformed to chemical energy in bacteria that possess the requisite secondary pathways. Some of these pathways rely on the activation of the aromatic acid by coenzyme A (CoA) thioesterification catalyzed by an aromatic acid: CoA ligase. Adaptation of such pathways to the bioremediation of man-made pollutants such as polychlorinated biphenyl (PCB) and dichlorodiphenyltrichloroethane (DDT) requires that the chlorinated benzoic acid byproduct that is formed be able to be eliminated by further degradation. To take advantage of natural benzoic acid degrading pathways requiring initial ring activation by thioesterification, the pathway aromatic acid:CoA ligase must be an effective catalyst with the chlorinated benzoic acid. This study, which focuses on the 4-chlorobenzoate:CoA ligase (CBL) of the 4-monochlorobiphenyl degrading bacterium Alcaligenes sp. strain ALP83, was carried out to determine if the 4-chlorobenzoate binding site of this enzyme can be transformed by rational design to recognize the chlorobenzoic acids formed in the course of breakdown of other environmental PCB congeners. The fundamental question addressed in this study is whether it is possible to add or subtract space from the substrate-binding pocket of this ligase (to complement the topology of the unnatural aromatic substrate) without causing disruption of the ligase catalytic machinery. Herein, we report the results of a substrate specificity analysis that, when interpreted within the context of the X-ray crystal structures, set the stage for the rational design of the ligase for thioesterification of two PCB-derived chlorobenzoic acids. The ligase was first optimized to catalyze CoA thioesterification of 3,4-dichlorobenzoic acid, a poor substrate, by truncating Ile303, a large hydrophobic residue that packs against the ring meta-C(H) group. The structural basis for the approximately 100-fold enhancement in the rate of 3,4-dichlorobenzoate thioesterification catalyzed by the I303A and I303G CBL mutants was validated by determination of the crystal structure of the 3,4-dichlorobenzoate-bound enzymes. Determinations of the structures of I303 mutant complexes of 3-chlorobenzoate, a very poor substrate, revealed nonproductive binding as a result of the inability of the substrate ring C(4)H group to fill the pocket that binds the C(4)Cl group of the native substrate. The C(4)Cl pocket of the CBL I303A mutant was then reduced in size by strategic amino acid replacement. A 54-fold improvement in catalytic efficiency was observed for the CBL F184W/I303A/V209T triple mutant. The results of this investigation are interpreted as evidence that the plasticity of the ligase catalytic scaffold is sufficient to allow expansion of substrate range by rational design. The combination of structural and kinetic analyses of the constructed mutants proved to be an effective approach to engineering the ligase for novel substrates.     

Antidiabetic potential of oleanolic acid from Ligustrum lucidum Ait

Ligustrum lucidum Ait. has been used in traditional Chinese medicine for over 1000 years because of its anti-tumor, antimutagenic, antidiabetic, and hepatoprotective properties. The aim of this study was to determine whether oleanolic acid (OA) is the principal active compound of L. lucidum responsible for its antidiabetic properties, and to examine its effect on the expression of thyroid hormones and insulin secretion, thus revealing the mechanism by which L. lucidum modulates insulin levels in diabetes. When rats with streptozotocin-induced diabetes were treated with OA (100 and 200 mg/kg body mass per day, for 40 days), the changes in blood glucose levels and in oral glucose tolerance tests showed that hypoglycemia was more pronounced in OA-treated groups than in the diabetic control rats, and that the levels of triglyceride, total cholesterol, and low-density lipoportein cholesterol in OA-treated rats were lower than those in the diabetic control rats, whose high-density lipoprotein cholesterol increased. OA-treated rats also gained weight, and exhibited increased serum insulin levels. In contrast, OA treatment did not effect the levels of thyroid hormone or TSH in rats with streptozotocin-induced diabetes. These results indicate that OA has hypoglycemic and hypolipidemic effects. OA treatment might stimulate insulin release, and consequently, results in the modulation of glucose levels and regulation of lipid metabolism.