Endothelial S1pr1 regulates pressure overload‐induced cardiac remodelling through AKT‐eNOS pathway

Cardiac vascular microenvironment is crucial for cardiac remodelling during the process of heart failure. Sphingosine 1‐phosphate (S1P) tightly regulates vascular homeostasis via its receptor, S1pr1. We therefore hypothesize that endothelial S1pr1 might be involved in pathological cardiac remodelling. In this study, heart failure was induced by transverse aortic constriction (TAC) operation. S1pr1 expression is significantly increased in microvascular endothelial cells (ECs) of post‐TAC hearts. Endothelial‐specific deletion of S1pr1 significantly aggravated cardiac dysfunction and deteriorated cardiac hypertrophy and fibrosis in myocardium. In vitro experiments demonstrated that S1P/S1pr1 praxis activated AKT/eNOS signalling pathway, leading to more production of nitric oxide (NO), which is an essential cardiac protective factor. Inhibition of AKT/eNOS pathway reversed the inhibitory effect of EC‐S1pr1‐overexpression on angiotensin II (AngII)‐induced cardiomyocyte (CM) hypertrophy, as well as on TGF‐β‐mediated cardiac fibroblast proliferation and transformation towards myofibroblasts. Finally, pharmacological activation of S1pr1 ameliorated TAC‐induced cardiac hypertrophy and fibrosis, leading to an improvement in cardiac function. Together, our results suggest that EC‐S1pr1 might prevent the development of pressure overload‐induced heart failure via AKT/eNOS pathway, and thus pharmacological activation of S1pr1 or EC‐targeting S1pr1‐AKT‐eNOS pathway could provide a future novel therapy to improve cardiac function during heart failure development.     

Cellularity and structure of fresh human coronary thrombectomy specimens; presence of cells with markers of progenitor cells

Acute coronary syndromes and acute myocardial infarctions are often related to plaque rupture and the formation of thrombi at the site of the rupture. We examined fresh coronary thrombectomy specimens from patients with acute coronary syndromes and assessed their structure and cellularity. The thrombectomy specimens consisted of platelets, erythrocytes and inflammatory cells. Several specimens contained multiple cholesterol crystals. Culture of thrombectomy specimens yielded cells growing in various patterns depending on the culture medium used. Culture in serum‐free stem cell enrichment medium yielded cells with features of endothelial progenitor cells which survived in culture for a year. Immunohistochemical analysis of the thrombi revealed cells positive for CD34, cells positive for CD15 and cells positive for desmin in situ, whereas cultured cell from thrombi was desmin positive but pancytokeratin negative. Cells cultured in endothelial cell medium were von Willebrand factor positive. The content of coronary thrombectomy specimens is heterogeneous and consists of blood cells but also possibly cells from the vascular wall and cholesterol crystals. The culture of cells contained in the specimens yielded multiplying cells, some of which demonstrated features of haematopoietic progenitor cells and which differentiated into various cell‐types.     

Protein Kinase D Promotes Airway Epithelial Barrier Dysfunction and Permeability through Down-regulation of Claudin-1

At the interface between host and external environment, the airway epithelium serves as a major protective barrier. In the present study we show that protein kinase D (PKD) plays an important role in the formation and integrity of the airway epithelial barrier. Either inhibition of PKD activity or silencing of PKD increased transepithelial electrical resistance (TEER), resulting in a tighter epithelial barrier. Among the three PKD isoforms, PKD3 knockdown was the most efficient one to increase TEER in polarized airway epithelial monolayers. In contrast, overexpression of PKD3 wild type, but not PKD3 kinase-inactive mutant, disrupted the formation of apical intercellular junctions and their reassembly, impaired the development of TEER, and increased paracellular permeability to sodium fluorescein in airway epithelial monolayers. We further found that overexpression of PKD, in particular PKD3, markedly suppressed the mRNA and protein levels of claudin-1 but had only minor effects on the expression of other tight junctional proteins (claudin-3, claudin-4, claudin-5, occludin, and ZO-1) and adherent junctional proteins (E-cadherin and β-catenin). Immunofluorescence study revealed that claudin-1 level was markedly reduced and almost disappeared from intercellular contacts in PKD3-overexpressed epithelial monolayers and that claudin-4 was also restricted from intercellular contacts and tended to accumulate in the cell cytosolic compartments. Last, we found that claudin-1 knockdown prevented TEER elevation by PKD inhibition or silencing in airway epithelial monolayers. These novel findings indicate that PKD negatively regulates human airway epithelial barrier formation and integrity through down-regulation of claudin-1, which is a key component of tight junctions.     

Genome Sequence of a Nicotine-Degrading Strain of Arthrobacter

We announce a 4.63-Mb genome assembly of an isolated bacterium that is the first sequenced nicotine-degrading Arthrobacter strain. Nicotine catabolism genes of the nicotine-degrading plasmid pAO1 were predicted, but plasmid function genes were not found. These results will help to better illustrate the molecular mechanism of nicotine degradation by Arthrobacter.     

GABAB receptor inhibits tumor progression and epithelial-mesenchymal transition via the regulation of Hippo/YAP1 pathway in colorectal cancer

Gamma-Aminobutyric Acid Type B Receptor (GABABR) plays essential roles in tumor progression. However, the function of GABABR in colorectal cancer (CRC) needs further clarification. As the main part of GABABR, GABABR1 expression was identified significantly lower in tumor tissues than those in non-tumor normal tissues and that CRC patients with high GABABR1 expression lived longer. Further studies indicated that knockdown of GABABR1 elevated CRC cell proliferation, migration, and invasion. Furthermore, knockdown of GABABR1 activated the expression of the epithelial-mesenchymal transition (EMT)-related proteins N-cadherin and Vimentin, whereas decrease the protein level of E-cadherin. In addition, activation of Hippo/YAP1 signaling contributes to the GABABR1 down-regulation promoted proliferation, migration, invasion and EMT in CRC cells. At last, we verified the contribution of Hippo/YAP1 signaling in the GABABR1 down-regulation impaired biological phenotype of colon cancer cells in vivo. In summary, these data indicate that GABABR1 impairs the migration and invasion of CRC cells by inhibiting EMT and the Hippo/YAP1 pathway, suggesting that GABABR1 could be a potential therapeutic target for CRC.     

Protective Effects of Lactobacillus plantarum CCFM8610 against Chronic Cadmium Toxicity in Mice Indicate Routes of Protection besides Intestinal Sequestration

Our previous study confirmed the ability of Lactobacillus plantarum CCFM8610 to protect against acute cadmium (Cd) toxicity in mice. This study was designed to evaluate the protective effects of CCFM8610 against chronic Cd toxicity in mice and to gain insights into the protection mode of this strain. Experimental mice were divided into two groups and exposed to Cd for 8 weeks via drinking water or intraperitoneal injection. Both groups were further divided into four subgroups, control, Cd only, CCFM8610 only, and Cd plus CCFM8610. Levels of Cd were measured in the feces, liver, and kidneys, and alterations of several biomarkers of Cd toxicity were noted. The results showed that when Cd was introduced orally, cotreatment with Cd and CCFM8610 effectively decreased intestinal Cd absorption, reduced Cd accumulation in tissue, alleviated tissue oxidative stress, reversed hepatic and renal damage, and ameliorated the corresponding histopathological changes. When Cd was introduced intraperitoneally, administration of CCFM8610 did not have an impact on tissue Cd accumulation or reverse the activities of antioxidant enzymes. However, CCFM8610 still offered protection against oxidative stress and reversed the alterations of Cd toxicity biomarkers and tissue histopathology. These results suggest that CCFM8610 is effective against chronic cadmium toxicity in mice. Besides intestinal Cd sequestration, CCFM8610 treatment offers direct protection against Cd-induced oxidative stress. We also provide evidence that the latter is unlikely to be mediated via protection against Cd-induced alteration of antioxidant enzyme activities.     

The Interactions of Glutathione-Capped CdTe Quantum Dots with Trypsin

Due to their unique fluorescent properties, quantum dots present a great potential for biolabelling applications; however, the toxic interactions of quantum dots with biopolymers are little known. The toxic interactions of glutathione-capped CdTe quantum dots with trypsin were studied in this paper using synchronous fluorescence spectroscopy, fluorescence emission spectra, and UV–vis absorption spectra. The interaction between CdTe quantum dots and trypsin resulted in structure changes of trypsin and inhibited trypsin's activity. Fluorescence emission spectra revealed that the quenching mechanism of trypsin by CdTe quantum dots was a static quenching process. The binding constant and the number of binding sites at 288 and 298 K were calculated to be 1.98 × 10⁶ L mol⁻¹ and 1.37, and 6.43 × 10⁴ L mol⁻¹ and 1.09, respectively. Hydrogen bonds and van der Waals' forces played major roles in this process.     

UV-B-induced DNA damage and repair pathways in polar Pseudogymnoascus sp. from the Arctic and Antarctic regions and their effects on growth,pigmentation and conidiogenesis

Solar radiation regulates most biological activities on Earth. Prolonged exposure to solar UV radiation can cause deleterious effects by inducing two major types of DNA damage, namely, cyclobutane pyrimidine dimers (CPDs) and pyrimidine 6-4 pyrimidone photoproducts. These lesions may be repaired by the photoreactivation (Phr) and nucleotide excision repair (NER) pathways; however, the principal UV-induced DNA repair pathway is not known in the fungal genus Pseudogymnoascus. In this study, we demonstrated that an unweighted UV-B dosage of 1.6 kJ m⁻² d⁻¹ significantly reduced fungal growth rates (by between 22% and 35%) and inhibited conidia production in a 10 d exposure. The comparison of two DNA repair conditions, light or dark, which respectively induced photoreactivation (Phr) and NER, showed that the UV-B-induced CPDs were repaired significantly more rapidly in light than in dark conditions. The expression levels of two DNA repair genes, RAD2 and PHR1 (encoding a protein in NER and Phr respectively), demonstrated that NER rather than Phr was primarily activated for repairing UV-B-induced DNA damage in these Pseudogymnoascus strains. In contrast, Phr was inhibited after exposure to UV-B radiation, suggesting that PHR1 may have other functional roles. We present the first study to examine the capability of the Arctic and Antarctic Pseudogymnoascus sp. to perform photoreactivation and/or NER via RT-qPCR approaches, and also clarify the effects of light on UV-B-induced DNA damage repair in vivo by quantifying cyclobutene pyrimidine dimers and pyrimidine 6-4 pyrimidone photoproducts. Physiological response data, including relative growth rate, pigmentation and conidia production in these Pseudogymnoascus isolates exposed to UV-B radiation are also presented.     

Enantioselective Synthesis and Antimicrobial Activities of Tetrahydro‐Β‐Carboline Diketopiperazines

A series of single isomers tetrahydro‐β‐carboline diketopiperazines were stereoselectively synthesized starting from l ‐tryptophan methyl ester hydrochloride and six aldehydes through a four‐step reaction including Pictet‐Spengler reaction, crystallization‐induced asymmetric transformations (CIAT), Schotten‐Baumann reaction, and intramolecular ester amidation. The chemical structures were characterized by nuclear magnetic resonance (NMR) and elemental analysis, among which two compounds were determined by x‐ray single crystal diffraction. Moreover, antimicrobial activities of all the compounds were also tested. Chirality 25:656–662, 2013. © 2013 Wiley Periodicals, Inc.