Dual roles of tight junction-associated protein, zonula occludens-1, in sphingosine 1-phosphate-mediated endothelial chemotaxis and barrier integrity

In this report, sphingosine-1-phosphate (S1P), a serum-borne bioactive lipid, is shown to activate tight-junction-associated protein Zonula Occludens-1 (ZO-1), which in turn plays a critical role in regulating endothelial chemotaxis and barrier integrity. After S1P stimulation, ZO-1 was redistributed to the lamellipodia and cell-cell junctions via the S1P1/G(i)/Akt/Rac pathway. Similarly, both endothelial barrier integrity and cell motility were significantly enhanced in S1P-treated cells through the G(i)/Akt/Rac pathway. Importantly, S1P-enhanced barrier integrity and cell migration were abrogated in ZO-1 knockdown cells, indicating ZO-1 is functionally indispensable for these processes. To investigate the underlying mechanisms, we demonstrated that cortactin plays a critical role in S1P-induced ZO-1 redistribution to the lamellipodia. In addition, S1P significantly induced the formation of endothelial tight junctions. ZO-1 and alpha-catenin polypeptides were colocalized in S1P-induced junctional structures; whereas, cortactin was not observed in these regions. Together, these results suggest that S1P induces the formation of two distinct ZO-1 complexes to regulate two different endothelial functions: ZO-1/cortactin complexes to regulate chemotactic response and ZO-1/alpha-catenin complexes to regulate endothelial barrier integrity. The concerted operation of these two ZO-1 complexes may coordinate two important S1P-mediated functions, i.e. migration and barrier integrity, in vascular endothelial cells.     

Sphingosine-1-phosphate signaling regulates lamellipodia localization of cortactin complexes in endothelial cells

Sphingosine-1-phosphate (S1P), a serum-borne lipid mediator, was demonstrated to be a potent chemoattractant of endothelial cells. It was recently shown that the colocalization of cortactin and actin related protein 2/3 (Arp2/3) in the lamellipodia is critical to S1P-induced endothelial chemotaxis. In this report, we describe that S1P-stimulated cortactin translocation to the cell periphery to form lamellipodia is specifically mediated by the endothelial S1P1 G-protein coupled receptor, and is regulated by G_i-mediated Akt-dependent S1P1 receptor phosphorylation and Cdc42/Rac activation pathways. In contrast to Src-dependent fibroblast growth factor-induced cortactin translocation, tyrosine phosphorylation cascades are not required for S1P-mediated lamellipodia formation and chemotaxis. Furthermore, we also demonstrate that S1P signaling, via the G_i/Akt/S1P1 phosphorylation/Rac pathway, regulates the cortactin–Arp2/3 complex formation, which ultimately results in membrane ruffling, formation of the lamellipodia and endothelial migration.J.F. Lee and H. Ozaki contributed equally to this work     

Secretion of long Abeta-related peptides processed at epsilon-cleavage site is dependent on the alpha-secretase pre-cutting

Abeta is the major component of amyloid in the brain in Alzheimer's disease and is derived from Alzheimer amyloid precursor protein (APP) by sequential proteolytic cleavage involving alpha-, beta- and gamma-secretase. Recently, gamma-secretase was shown to cleave near the cytoplasmic membrane boundary of APP (called the epsilon-cleavage), as well as in the middle of the membrane domain (gamma-cleavage). However, the precise relationship between gamma- and epsilon-cleavage is still unknown. In this paper, I analyzed Abeta-related peptides using immunoprecipitation and liquid chromatography ion trap mass spectrometer and found some long Abeta-related peptides, starting at Abeta residues 16Lys-23Asp and ending at 43Thr-52Leu, in the culture media of COS-1 cells and in human brain extract. These results indicated that longer Abeta-related peptides cleaved at epsilon-cleavage site were secreted under normal conditions and were dependent on the alpha-secretase cleavage products.     

An adult with atopic dermatitis and repeated short-term fasting

It has been reported that nutritional stress, such as short-term fasting and long-term energy restriction, has a suppressive effect on allergic dermatitis in experimental animals. Furthermore, clinical study has demonstrated a positive association between weight loss by low-energy diet and improvement in patients with atopic dermatitis. In this report, a 23-year-old female with atopic dermatitis received a treatment of repeated short-term fasting. 24-hour fasting was conducted once a week for a period of 20 weeks. On the fasting day, the amount of energy intake was 200 kcal. No medication was administered during the trial period. Clinical symptoms were evaluated using the Scoring Atopic Dermatitis index, and IgE, lactase dehydrogenase-5, and number of eosinophils were measured. At the end of the trial, body weight was reduced and clinical symptoms improved, whereas no improvements in laboratory findings were shown. For sufficient evidence of the effects of fasting, additional controlled study is needed.     

A new method for selective epoxidation and a biogenetic-type synthesis of linalyloxides

[2.3]Sigmatropic rearrangement and successive selective epoxidation of geranyl selenide (2), citronellyl selenide (4), and farnesyl selenide (6) are described, and a simple synthesis of trans-(15) and cis-linalyloxides (16) along biosynthetic lines is also reported.     

Inhibitory mechanism of cis-polyunsaturated fatty acids on platelet aggregation: the relation with their effects on Ca2+ mobilization, cyclic AMP levels and membrane fluidity

The in vitro inhibitory effects of cis-polyunsaturated fatty acids, linolenic (18:2 delta 9,12), alpha-linoleic (18:3 delta 9,12,15) and eicosatrienoic (20:3 delta 11,14,17) acid, on bovine platelet aggregation and their inhibitory mechanism were investigated. These fatty acids inhibited platelet aggregation induced by ADP and thrombin to similar extent. Fluorescence analyses with fura-2-loaded platelets showed that, in the concentration ranges that inhibited aggregation, they also inhibited agonist-induced increase in cytoplasmic Ca2+. According to radioimmunoassay study, addition of these fatty acids increased cyclic AMP contents in the presence of theophylline corresponded with their inhibitory effects on aggregation. These fatty acids induced a 1.6-1.8-fold increase over basal concentration of cyclic AMP in the concentration ranges that fully inhibited aggregation. On the other hand, saturated fatty acid, stearic acid, affected neither aggregation nor cyclic AMP levels. As reported previously [1985) Biochim. Biophys. Acta 818, 391), these unsaturated fatty acids induced increase in membrane fluidity in the same concentration range. These results suggest that inhibition of platelet aggregation by cis-polyunsaturated fatty acids is due to the increase in cyclic AMP levels. This increase seems to be due to stimulation of adenylate cyclase which is mediated by membrane perturbation.     

Phosphoinositide 3-kinaseγ controls the intracellular localization of CpG to limit DNA-PKcs-dependent IL-10 production in macrophages

Synthetic oligodeoxynucleotides containing unmethylated CpG motifs (CpG) stimulate innate immune responses. Phosphoinositide 3-kinase (PI3K) has been implicated in CpG-induced immune activation; however, its precise role has not yet been clarified. CpG-induced production of IL-10 was dramatically increased in macrophages deficient in PI3Kγ (p110γ(-/-)). By contrast, LPS-induced production of IL-10 was unchanged in the cells. CpG-induced, but not LPS-induced, IL-10 production was almost completely abolished in SCID mice having mutations in DNA-dependent protein kinase catalytic subunit (DNA-PKcs). Furthermore, wortmannin, an inhibitor of DNA-PKcs, completely inhibited CpG-induced IL-10 production, both in wild type and p110γ(-/-) cells. Microscopic analyses revealed that CpG preferentially localized with DNA-PKcs in p110γ(-/-) cells than in wild type cells. In addition, CpG was preferentially co-localized with the acidic lysosomal marker, LysoTracker, in p110γ(-/-) cells, and with an early endosome marker, EEA1, in wild type cells. Over-expression of p110γ in Cos7 cells resulted in decreased acidification of CpG containing endosome. A similar effect was reproduced using kinase-dead mutants, but not with a ras-binding site mutant, of p110γ. Thus, it is likely that p110γ, in a manner independent of its kinase activity, inhibits the acidification of CpG-containing endosomes. It is considered that increased acidification of CpG-containing endosomes in p110γ(-/-) cells enforces endosomal escape of CpG, which results in increased association of CpG with DNA-PKcs to up-regulate IL-10 production in macrophages.     

The Roles of Sodium and Potassium Ions in the Generation of the Electro-Olfactogram

In order to clarify whether or not the electronegative olfactory mucosal potentials (EOG) are generator potentials, the effects of changed ionic enviroment were studied. The EOG decreased in amplitude and in some cases nearly or completely disappeared, when Na⁺ in the bathing Ringer solution was replaced by sucrose, Li⁺, choline⁺, tetraethylammonium⁺ (TEA), or hydrazine. In the K⁺-free Ringer solution, the negative EOG's initially increased and then decreased in amplitude. In Ringer's solution with increased K⁺, the negative EOG's increased in amplitude. When K⁺ was increased in exchange for Na⁺ in Ringer's solution, the negative EOG's decreased, disappeared, and then reversed their polarity (Fig. 6). Next, when the K⁺ was replaced by equimolar sucrose, Li⁺, choline⁺, TEA⁺, hydrazine, or Na⁺, the reversed potentials recovered completely only in Na⁺-Ringer's solution, but never in the other solutions. Thus, the essential role of Na⁺ and K⁺ in the negative EOG's was demonstrated. Ba⁺⁺ was found to depress selectively the electropositive EOG, but it hardly decreased and never increased the negative EOG. Hence, it is concluded that Ba⁺⁺ interferes only with Cl^- influx, and that the negative EOG's are elicited by an increase in permeability of the olfactory receptive membrane to Na⁺ and K⁺, but not to Cl^-. From the ionic mechanism it is inferred that the negative EOG's are in most cases composites of generator and positive potentials.     

Chemical constituents of cape aloe and their synergistic growth-inhibiting effect on Ehrlich ascites tumor cells

The constituents of cape aloe were investigated after a preliminary screening of the growth-inhibiting effect on Ehrlich ascites tumor cells (EATC) of several extracts of this plant. Ten compounds were isolated from the dichloromethane (CH(2)Cl(2)) extract that showed the strongest activity, and their structures were elucidated as aloe-emodin (1), p-hydroxybenzaldehyde (2), p-hydroxyacetophenone (3), pyrocatechol (4), 10-oxooctadecanoic acid (5), 10-hydroxyoctadecanoic acid (6), methyl 10-hydroxyoctadecanoate (7), 7-hydroxy-2,5-dimethylchromone (8), furoaloesone (9), and 2-acetonyl-8-(2-furoylmethyl)-7-hydroxy-5-methylchromone (10) based on MS and various NMR spectroscopic techniques. Compounds 2-7 were isolated for the first time from cape aloe. Compounds 4-7 and 10 showed a significant growth-inhibiting effect, and compound 1 exhibited a remarkable synergistic effect on compounds 8-10, which was not observed with the treatment by each compound alone on EATC. These results suggest that the strong growth-inhibiting effect of the CH(2)Cl(2) extract was dependent not on one compound alone, but on the synergistic effect from the combination of compound 1 and the other compounds.     

Novel pyrazolo[1,5-a]pyrimidines as c-Src kinase inhibitors that reduce IKr channel blockade

To improve the in vitro potency of the c-Src inhibitor 1a and to address its hERG liability, a structure-activity study was carried out, focusing on two regions of the lead compound. The blockade of the delayed cardiac current rectifier K(+) (I(Kr)) channel was overcome by replacing the ethylenediamino group with an amino alcohol group at the 7-position. In addition, modifying the substituents at the 5-position and the side chain groups on the amino alcohols at the 7-position enhanced the intracellular c-Src inhibitory activity and increased central nervous system (CNS) penetration. In the present study, 6l exhibited significant in vivo efficacy in a middle cerebral artery (MCA) occlusion model in rats.