LOXL1‐AS1 communicating with TIAR modulates vasculogenic mimicry in glioma via regulation of the miR‐374b‐5p/MMP14 axis

At present, growing evidence indicates that long non‐coding RNAs (lncRNAs) participate in the progression of glioma. The function of LOXL1‐AS1 in vasculogenic mimicry (VM) in glioma remains unclear. First, the expressions of TIAR, the lncRNA LOXL1‐AS1, miR‐374b‐5p and MMP14 were examined by qRT‐PCR and Western blot in both, glioma tissues and glioma cell lines. Proliferation, migration, invasion and tube formation assays were conducted to evaluate the roles of TIAR, LOXL1‐AS1, miR‐374b‐5p and MMP14 in malignant cellular behaviours in glioma cells. A nude mouse xenograft model and dual staining for CD34 and PAS were used to assess whether VM was affected by TIAR, LOXL1‐AS1 or miR‐374b‐5p in vivo. In this study, low levels of TIAR and high levels of LOXL1‐AS1 were found in glioma cells and tissues. TIAR downregulated the expression of LOXL1‐AS1 by destabilizing it. LOXL1‐AS1 acted like a miRNA sponge towards miR‐374b‐5p so that downregulation of the former greatly inhibited cell proliferation, migration, invasion and VM. Additionally, miR‐374b‐5p overexpression repressed malignant biological behaviours and VM in glioma by modifying MMP14. In summary, we demonstrated that TIAR combined with LOXL1‐AS1 modulates VM in glioma via the miR‐374b‐5p/MMP14 axis, revealing novel targets for glioma therapy.     

Thymoquinone ameliorates pressure overload‐induced cardiac hypertrophy by activating the AMPK signalling pathway

Prolonged pathological myocardial hypertrophy leads to end‐stage heart failure. Thymoquinone (TQ), a bioactive component extracted from Nigella sativa seeds, is extensively used in ethnomedicine to treat a broad spectrum of disorders. However, it remains unclear whether TQ protects the heart from pathological hypertrophy. This study was conducted to examine the potential utility of TQ for treatment of pathological cardiac hypertrophy and if so, to elucidate the underlying mechanisms. Male C57BL/6J mice underwent either transverse aortic constriction (TAC) or sham operation, followed by TQ treatment for six consecutive weeks. In vitro experiments consisted of neonatal rat cardiomyocytes (NRCMs) that were exposed to phenylephrine (PE) stimulation to induce cardiomyocyte hypertrophy. In this study, we observed that systemic administration of TQ preserved cardiac contractile function, and alleviated cardiac hypertrophy, fibrosis and oxidative stress in TAC‐challenged mice. The in vitro experiments showed that TQ treatment attenuated the PE‐induced hypertrophic response in NRCMs. Mechanistical experiments showed that supplementation of TQ induced reactivation of the AMP‐activated protein kinase (AMPK) with concomitant inhibition of ERK 1/2, p38 and JNK1/2 MAPK cascades. Furthermore, we demonstrated that compound C, an AMPK inhibitor, abolished the protective effects of TQ in in vivo and in vitro experiments. Altogether, our study disclosed that TQ provides protection against myocardial hypertrophy in an AMPK‐dependent manner and identified it as a promising agent for the treatment of myocardial hypertrophy.     

Analysis of the PilQ secretin from Neisseria meningitidis by transmission electron microscopy reveals a dodecameric quaternary structure

PilQ is a member of the secretin family of outer membrane proteins and is specifically involved in secretion of type IV pili in Neisseria meningitidis, Neisseria gonorrhoeae, and Pseudomonas aeruginosa. The quaternary structure of PilQ from N. meningitidis was analyzed by transmission electron microscopy by using a negative stain. Single particle averaging was carried out with a total data set of 650 individual particles, which produced a projection map generated from 296 particles at an estimated resolution of 2.6 nm. Oligomeric PilQ adopts a donut-like structure with an external ring that is 16.5 nm in diameter surrounding a central cavity that is 6.5 nm in diameter. Self-rotation and power spectrum analysis demonstrated the presence of 12-fold rotational symmetry, showing that PilQ is organized as a ring of 12 identical subunits. A model of the type IV meningococcal pilus fiber, based on the X-ray crystal structure of the N. gonorrhoeae pilin subunit, fitted neatly into the cavity, demonstrating how PilQ could serve as a channel for the growing pilus fiber.     

拟双角斯氏线虫生物学特性的研究

本文对拟双角斯氏线虫Ｄ－４－３品系的生物学特性进行了研究。     

Characterization of two Pseudomonas putida lipopeptide biosurfactants, putisolvin I and II, which inhibit biofilm formation and break down existing biofilms

Pseudomonas putida strain PCL1445 was isolated from roots of plants, grown on a site polluted with polycyclic aromatic hydrocarbons. PCL1445 produces biosurfactant activity at the end of the exponential growth phase. High-performance liquid chromatography (HPLC) analysis of supernatant extracts of PCL1445 showed two peaks with surface-tension reducing activity, tentatively assigned as biosurfactants putisolvin I and putisolvin II and was followed by structural analyses. A transposon mutant of PCL1445, strain PCL1436, which lacks the two surface-active peaks appeared to be mutated in an open reading frame (ORF) with amino acid homology to various lipopeptide synthetases. Structural analyses of the two biosurfactants of PCL1445 revealed that both are novel cyclic lipodepsipeptides with a hexanoic lipid chain connected to the N-terminus of a 12-amino-acid peptide moiety, in which the C-terminal carboxylic acid group forms an ester with the hydroxyl side-chain of Ser9. The difference between the two structures is located in the second amino acid from the C-terminus, being valine for putisolvin I, and leucine/isoleucine for putisolvin II. We show that these novel compounds lower the surface tension and influence the biofilm development on polyvinyl chloride (PVC). Biofilm formation of the bio-synthetic mutant PCL1436 was strongly increased containing more cells, which formed aggregates earlier as compared with wild-type PCL1445 biofilms. Using purified putisolvin I and II it was shown that biofilm formation of different Pseudomonas strains was inhibited and most interestingly, that both putisolvins are also able to break down existing Pseudomonas biofilms.     

Male mouse meiotic chromosome cores deficient in structural proteins SYCP3 and SYCP2 align by homology but fail to synapse and have possible impaired specificity of chromatin loop attachment

The targeted deletion of the meiotic chromosome core component MmSYCP3 results in chromosome synaptic failure at male meiotic prophase, extended meiotic chromosomes, male sterility, oocyte aneuploidy and absence of the MmSYCP2 chromosome core component. To test the functions of SYCP2 and SYCP3 proteins in the cores, we determined the effect of their deletion on homology recognition by whole chromosome painting and the effect on chromatin loop attachment to the cores with endogenous and exogenous sequences. Because we observed that the alignment of cores is between homologs, it suggested that alignment is not a function of the chromosome core components but might be mediated by chromatin-chromatin interactions. The alignment function therefore appears to be separate from intimate synapsis function of homologous cores that is observed to be defective in the SYCP3-/- males. To examine the functions of the SYCP2 and 3 core proteins in chromatin loop attachment, we measured the loop sizes of the centromeric major satellite chromatin and the organization of an exogenous transgene in SYCP3+/+ and SYCP3-/- males. We observed that these satellite chromatin loops have a normal appearance in SYCP3-/- males, but the loop regulation of a 2-Mb exogenous lambda phage insert appears to be altered. Normally the insert fails to attach to the core except by flanking endogenous sequences, but in the absence of SYCP2 and SYCP3, there appears to be multiple attachments to the core. This suggests that the selective preference for the attachment of mouse sequences to the chromosome core in the wild-type male is impaired in the SYCP3-/- male. Apparently the SYCP2 and SYCP3 proteins function in the specificity of chromatin attachment to the chromosome core.