ATM mediates interdependent activation of p53 and ERK through formation of a ternary complex with p-p53 and p-ERK in response to DNA damage

DNA damage in eukaryotic cells induces signaling pathways mediated by the ATM, p53 and ERK proteins, but the interactions between these pathways are not completely known. To address this issue, we performed a time course analysis in human embryonic fibroblast cells treated with DNA-damaging agents. DNA damage induced the phosphorylation of p53 at Ser 15 (p-p53) and the phosphorylation of ERK (p-ERK). Inhibition of p53 by a dominant negative mutant or in p53(-/-) fibroblast cells abolished ERK phosphorylation. ERK inhibitor prevented p53 phosphorylation, indicating that phosphorylations of p53 and p-ERK are interdependent each other. A time course analysis showed that ATM interacted with p-p53 and p-ERK in early time (0.5 h) and interaction between ATM-bound p-p53 and p-ERK or ATM-bound p-ERK and p-p53 occurred in late time (3 h) of DNA damage. These results indicate that ATM mediates interdependent activation of p53 and ERK through formation of a ternary complex between p-p53 and p-ERK in response to DNA damage to cause growth arrest.     

Combined application of bacterial predation and carbon dioxide aerosols to effectively remove biofilms

This study evaluated predation with Bdellovibrio bacteriovorous and CO(2) aerosol spraying to remove fluorescent Escherichia coli biofilms from silicon chips. Initial tests found that 7.5×10(5) viable E. coli cells were dispersed into the surrounding environment during aerosol treatment. The total number dispersed per test decreased to only 16 for predated biofilms. This is nearly 50,000-fold lower compared to untreated chips and 1000-fold lower compared to chips soaked in HEPES buffer only. Both scanning electron microscopy (SEM) and fluorescent microscopy analyses confirmed that predation alone did not completely eradicate the biofilm population. When used in conjunction with CO(2) aerosols, however, no fluorescent signals remained and the SEM pictures showed a pristine surface devoid of bacteria. Consequently, this study demonstrates these two methods can be used with each other to significantly remove biofilms from surfaces while also significantly reducing the likelihood of human exposure to potential pathogens during their removal.     

Gas-phase removal of biofilms from various surfaces using carbon dioxide aerosols

The present study evaluated the removal of Escherichia coli XL1-blue biofilms using periodic jets of carbon dioxide aerosols (a mixture of solid and gaseous CO(2)) with nitrogen gas. The aerosols were generated by the adiabatic expansion of high-pressure CO(2) gas through a nozzle and used to remove air-dried biofilms. The areas of the biofilms were measured from scanning electron micrographs before and after applying the aerosols. The removal efficiency of the aerosol treatment was measured with various air-drying times of the biofilms before the treatment, surface materials, and durations of CO(2) aerosols in each 8-s aerosol-nitrogen cleaning cycle. Nearly 100% of the fresh biofilms were removed from the various surfaces very reliably within 90?s. This technique can be useful for removing unsaturated biofilms on solid surfaces and has potential applications for cleaning bio-contaminated surfaces.     

TUT7 controls the fate of precursor microRNAs by using three different uridylation mechanisms

Terminal uridylyl transferases (TUTs) function as integral regulators of microRNA (miRNA) biogenesis. Using biochemistry, single-molecule, and deep sequencing techniques, we here investigate the mechanism by which human TUT7 (also known as ZCCHC6) recognizes and uridylates precursor miRNAs (pre-miRNAs) in the absence of Lin28. We find that the overhang of a pre-miRNA is the key structural element that is recognized by TUT7 and its paralogues, TUT4 (ZCCHC11) and TUT2 (GLD2/PAPD4). For group II pre-miRNAs, which have a 1-nt 3′ overhang, TUT7 restores the canonical end structure (2-nt 3′ overhang) through mono-uridylation, thereby promoting miRNA biogenesis. For pre-miRNAs where the 3′ end is further recessed into the stem (as in 3′ trimmed pre-miRNAs), TUT7 generates an oligo-U tail that leads to degradation. In contrast to Lin28-stimulated oligo-uridylation, which is processive, a distributive mode is employed by TUT7 for both mono- and oligo-uridylation in the absence of Lin28. The overhang length dictates the frequency (but not duration) of the TUT7-RNA interaction, thus explaining how TUT7 differentiates pre-miRNA species with different overhangs. Our study reveals dual roles and mechanisms of uridylation in repair and removal of defective pre-miRNAs.     

A Leap Forward Towards Unraveling Newer Anti-infective Agents from an Unconventional Source: a Draft Genome Sequence Illuminating the Future Promise of Marine Heterotrophic Bacillus sp. Against Drug-Resistant Pathogens

Marine Biotechnology - During the previous decade, genome-built researches on marine heterotrophic microorganisms displayed the chemical heterogeneity of natural product resources coupled with the...     

Aqueous Extract of Bambusae Caulis in Taeniam Inhibits PMA-Induced Tumor Cell Invasion and Pulmonary Metastasis: Suppression of NF-κB Activation through ROS Signaling

Bamboo shavings (Bambusae Caulis in Taeniam, BCT) are widely used as a traditional Chinese medicine to control hypertension and cardiovascular disease, and to alleviate fever, vomiting, and diarrhea. It has been demonstrated that BCT reduces ovalbumin-induced airway inflammation by regulating pro-inflammatory cytokines, and decreases tumor growth in tumor-bearing mice. However, the effects of BCT on the metastatic potential of malignant cancer cells and the detailed mechanism of its anti-metastatic activity have not been examined previously. In this study, we investigated whether an aqueous extract of BCT (AE-BCT) reduces the metastatic potential of HT1080 cells, and elucidated the underlying anti-metastatic mechanism. In addition, we examined whether AE-BCT administration inhibits pulmonary metastasis of intravenously injected B16F10 cells in C57BL/6J mice. AE-BCT (50–250 µg/ml) dose-dependently suppressed colony-forming activity under anchorage-dependent and -independent growth conditions. Pretreatment with AE-BCT efficiently inhibited cell migration, invasion, and adhesion. AE-BCT also dramatically suppressed PMA-induced MMP-9 activity and expression by blocking NF-κB activation and ERK phosphorylation. Production of intracellular ROS, a key regulator of NF-κB-induced MMP-9 activity, was almost completely blocked by pretreatment with AE-BCT. Furthermore, daily oral administration of AE-BCT at doses of 50 and 100 mg/kg efficiently inhibited lung metastasis of B16F10 cells injected into the tail veins of C57BL/6J mice with no systemic toxicity. These results demonstrate that AE-BCT significantly reduced the metastatic activity of highly malignant cancer cells by suppressing MMP-9 activity via inhibition of ROS-mediated NF-κB activation. These results indicate that AE-BCT may be a safe natural product for treatment of metastatic cancer.     

Heterologous production of Pseudomonas aeruginosa EMS1 biosurfactant in Pseudomonas putida

A new bacterial strain isolated from activated sludge, identified as Pseudomonas aeruginosa EMS1, produced a biosurfactant when grown on acidified soybean oil as the sole carbon source. An optimum biosurfactant production of 5 g/L was obtained with the following medium composition: 2% acidified soybean oil, 0.3% NH4NO3, 0.03% KH2PO4, 0.03% K2HPO4, 0.02% MgSO4.7H2O and 0.025% CaCl2.2H2O, with shaking at 200 rpm for an incubation period of 100 h at 30 degrees C. The production of the biosurfactant was found to be a function of cell growth, with maximum production occurring during the exponential phase. Hemolysis of erythrocytes and thin-layer chromatography studies revealed that the secreted biosurfactant was rhamnolipid. To overcome the complex environmental regulation with respect to rhamnolipid biosynthesis, and to replace the opportunistic pathogen P. aeruginosa with a safe industrial strain, attempts were made to achieve rhamnolipid production in a heterologous host, Pseudomonas putida, using molecular cloning of rhlAB rhamnosyltransferase genes with the rhlRI quorum sensing system, assuming that a functional rhamnosyltransferase would catalyze the formation of rhamnosyl-6-hydroxydecanoyl-6-hydroxydecanoate (mono-rhamnolipid) in P. putida. It was shown that rhamnolipid can be produced in the heterologous strain, P. putida, when provided with the rhamnosyltransferase genes.