A Novel Biosurfactant Produced by Aureobasidium pullulans L3-GPY from a Tiger Lily Wild Flower,Lilium lancifolium Thunb.

Yeast biosurfactants are important biotechnological products in the food industry, and they have medical and cosmeceutical applications owing to their specific modes of action, low toxicity, and applicability. Thus, we have isolated and examined biosurfactant-producing yeast for various industrial and medical applications. A rapid and simple method was developed to screen biosurfactant-producing yeasts for high production of eco-friendly biosurfactants. Using this method, several potential niches of biosurfactant-producing yeasts, such as wild flowers, were investigated. We successfully selected a yeast strain, L3-GPY, with potent surfactant activity from a tiger lily, Lilium lancifolium Thunb. Here, we report the first identification of strain L3-GPY as the black yeast Aureobasidium pullulans. In addition, we isolated a new low-surface-tension chemical, designated glycerol-liamocin, from the culture supernatant of strain L3-GPY through consecutive chromatography steps, involving an ODS column, solvent partition, silica gel, Sephadex LH-20, and an ODS Sep-Pak cartridge column. The chemical structure of glycerol-liamocin, determined by mass spectrometry and nuclear magnetic resonance spectroscopy, indicates that it is a novel compound with the molecular formula C₃₃H₆₂O₁₂. Furthermore, glycerol-liamocin exhibited potent biosurfactant activity (31 mN/m). These results suggest that glycerol-liamocin is a potential novel biosurfactantfor use in various industrial applications.     

Differentially up-regulated genes in proliferating porcine neonatal pancreas cells caused by epidermal growth factor

Pancreatic duct cells are considered to be a major source for beta-cell regeneration or neogenesis. Although epidermal growth factor (EGF) is a well-known important growth factor for pancreas development, the control of pancreatic duct cell growth and differentiation by EGF is poorly understood. In this study, we focused on identifying the genes that were differentially up-regulated in response to EGF stimulation using monolayer cultured porcine neonatal pancreas cells. Cells were obtained from 1 to 3 day old pigs, dispersed and cultured for 8 days. Monolayer cultured porcine pancreas cells were comprised of duct cells and some endocrine and mesenchymal cells (75.2 +/- 15.1, 19.6 +/- 4.9, and 9.5 +/- 3.1%, respectively). After 16 h in serum free media, cells were treated with 100 microg/L EGF for 24 h. Differentially expressed genes were screened by subtractive hybridization. (3)H-thymidine uptake was significantly increased by EGF with time (untreated vs. 24 h treated, untreated vs. 48 h treated: 305.5 +/- 3.5 cpm vs. 380.3 +/- 17.3 cpm (P < 0.05), 309.2 +/- 4.51 vs. 929 +/- 9.19 cpm, (P < 0.005), respectively). Three hundred and fifty cDNA clones were obtained by subtractive hybridization and the inserts were confirmed in 161 colonies and then sequenced. Finally, we found increased mRNA expression of five unknown and five known genes, including cytochrome c oxidase subunit I (COI), cyclooxygenase-2 (COX-2), matrix metalloproteinase-13 (MMP-13), Wiskott-Aldrich syndrome protein interacting protein (WASPIP), and hyaluronan synthase-2 (HAS-2). We confirmed the up-regulation of these genes by Northern blot and semi-quantitative RT-PCR at various time points. The present findings opened new targets for the research on the mechanisms of pancreatic duct cell proliferation by EGF.     

Modulation of beta-catenin phosphorylation/degradation by cyclin-dependent kinase 2

beta-Catenin functions as a downstream component of the Wnt/Wingless signal transduction pathway, and inappropriate control of cytosolic beta-catenin is a crucial step in the genesis of several human cancers. Here we demonstrate that cyclin-dependent kinase 2 (CDK2) in association with cyclin A or cyclin E directly binds to beta-catenin. In vivo and in vitro kinase assays with cyclin-CDK2 demonstrate beta-catenin phosphorylation on residues Ser(33), Ser(37), Thr(41), and Ser(45). This phosphorylation promotes rapid degradation of cytosolic beta-catenin via the beta-TrCP-mediated proteasome pathway. Moreover, cyclin E-CDK2 contributes to rapid degradation of cytosolic beta-catenin levels during G(1) phase by regulating beta-catenin phosphorylation and subsequent degradation. In this way, CDK2 may "fine tune" beta-catenin levels over the course of the cell cycle.     

Nox 2 stimulates muscle differentiation via NF-kappaB/iNOS pathway

The NF-kappaB/iNOS pathway stimulates muscle differentiation downstream of the PI 3-kinase/p38 MAPK pathway and diverse antioxidants block muscle differentiation. Therefore, we here investigated whether Nox 2 links those two myogenic pathways in H9c2 and C2C12 myoblasts. Compared with the proliferation stage, ROS generation was enhanced from the early stage of differentiation and gradually increased as differentiation progressed. Antioxidants suppressed the activated NF-kappaB/iNOS pathway during muscle differentiation. Nox 2 activity was also increased during muscle differentiation. Treatment with DPI and apocynin, two inhibitors of NADPH oxidase, and suppression of Nox 2 expression using siRNA, but not Nox 1, inhibited NADPH oxidase activity, muscle differentiation, and the NF-kappaB/iNOS pathway. Inhibition of PI 3-kinase and p38 MAPK suppressed the Nox 2/NF-kappaB/iNOS pathway. Nitric oxide restored muscle differentiation blocked by treatment with antioxidants or suppression of the Nox 2/NF-kappaB/iNOS pathway. In conclusion, Nox 2 stimulates muscle differentiation downstream of the PI 3-kinase/p38 MAPK pathway by activating the NF-kappaB/iNOS pathway via ROS generation.