Epigallocatechin-3-gallate, constituent of green tea, suppresses the LPS-induced phenotypic and functional maturation of murine dendritic cells through inhibition of mitogen-activated protein kinases and NF-kappaB

The effects of epigallocatechin-3-gallate (EGCG) on dendritic cells (DC) maturation were investigated. EGCG, in a dose-dependent manner, profoundly inhibited CD80, CD86, and MHC class I and II expression on bone marrow-derived murine myeloid DC. EGCG restored the decreased dextran-FITC uptake and inhibited enhanced IL-12 production by LPS-treated DC. EGCG-treated DC were poor stimulators of nai;ve allogeneic T-cell proliferation and reduced levels of IL-2 production in responding T cells. EGCG-pretreated DC inhibited LPS-induced MAPKs, such as ERK1/2, p38, JNK, and NF-kappaB p65 translocation. Therefore, the molecular mechanisms by which EGCG antagonized LPS-induced DC maturation appeared to involve the inhibition of MAPK and NF-kappaB activation. These novel findings provide new insight into the immunopharmacological role of EGCG and suggest a novel approach to the manipulation of DC for therapeutic application of autoimmune and allergic diseases.     

Physiological concentration of atrial natriuretic peptide induces endothelial regeneration in vitro

Both nitric oxide (NO) and natriuretic peptides produce apoptosis of vascular smooth muscle cells. However, there is evidence that NO induces endothelial cell proliferation, which suggests that there is a difference in the response of endothelial cells to natriuretic peptides. The purpose of this study was to investigate the effect of atrial natriuretic peptide (ANP) on human endothelial cell survival. ANP within the physiological concentration (10(-11) mol/l) induced a 52% increase in the number of human coronary arterial endothelial cells and a 63% increase in human umbilical vein endothelial cells at a low concentration of serum. The increase in cell numbers was blocked by pretreatment with RP8-CPT-cGMP (RP8), a cGMP-dependent protein kinase inhibitor, with wortmannin, an Akt/PKB inhibitor, and with PD-98059, an ERK1/2 inhibitor. In a Transwell migration test, ANP also increased the cell migration, and RP8, wortmannin, and PD-98059 blocked this increase. A wound healing assay was performed to examine the effects of ANP on regeneration in vitro. ANP increased both cell numbers and migration, but the effects were blocked by the above three kinase inhibitors. ANP increased the expression of phospho-Akt and of phospho-ERK1/2 within 1.5 h. These results suggest that ANP can potentiate endothelial regeneration by cGMP-dependent protein kinase stimulation and subsequent Akt and ERK1/2 activations.     

pHP489, a Helicobacter pylori small cryptic plasmid, harbors a novel gene coding for a replication initiation protein

We have analyzed a Helicobacter pylori plasmid, pHP489. The 1222-bp nucleotide sequence had one open reading frame, a DnaA-binding site, one direct repeat, and three inverted repeats. The (G+C) content of pHP489 was 33.3%. Although the nucleic acid sequence and deduced amino acid sequence were homologous to those of other bacterial plasmid Rep proteins, the degree of similarity was very low. A deletion analysis showed that the Rep protein was not required for the replication of pHP489 in its H. pylori host, but the host replication machinery was needed.     

Expression of an artificial polypeptide with a repeated tripeptide glutamyl-tryptophanyl-lysine in Saccharomyces cerevisiae

AIMS: Artificial genes, which encode 48 or 64 repeats of a tripeptide, glutamyl-tryptophanyl-lysine have been cloned to the yeast expression vector pAM82 containing the PHO5 promoter and expressed in Saccharomyces cerevisiae AH22. METHODS AND RESULTS: When the yeast cells harbouring recombinant plasmids pALTG6-2 and pALTG4-4 were derepressed in Burkholder minimal medium (Toh-e, A., Ueda, Y., Kakimoto, S.I. and Oshima, Y. (1973) Journal of Bacteriology113, 727-738) containing low phosphate (0.03 g l-1 KH2PO4 and 1.5 g l-1 KCl), the expression was the highest after 24 h induction and the artificial polypeptides were synthesized to about 10% (pALTG6-2) and 14% (pALTG4-4) of the total cell protein. CONCLUSIONS: The artificial polypeptides produced in yeast were made to react with the rabbit antiserum against the polypeptide purified from Escherichia coli and found only in the pellet fraction of cell lysates, indicating the formation of inclusion body. Artificial polypeptide consisting of Glu-Trp-Lys may be useful as partial supplement in food and feeds. SIGNIFICANCE AND IMPACT OF THE STUDY: The production of single cell enriched with homopolymers of an essential amino acid in yeast might be an important tool of supplementing cereal diets and feed grain rations and could be used as means for improvement of the amino acid profile of single cell protein and production of pharmaceutical peptides.     

Cytochrome P450-catalyzed brassinosteroid pathway activation through synthesis of castasterone and brassinolide in Phaseolus vulgaris

The last reaction in the biosynthesis of brassinolide has been examined enzymatically. A microsomal enzyme preparation from cultured cells of Phaseolus vulgaris catalyzed a conversion from castasterone to brassinolide, indicating that castasterone 6-oxidase (brassinolide synthase) is membrane associated. This enzyme preparation also catalyzed the conversions of 6-deoxocastasterone and typhasterol to castasterone which have been reported to be catalyzed by cytochrome P450s, CYP85A1 of tomato and CYP92A6 of pea, respectively. The activities of these enzymes require molecular oxygen as well as NADPH as a cofactor. The enzyme activities were strongly inhibited by carbon monoxide, an inhibitor of cytochrome P450, and this inhibition was recovered by blue light irradiation in the presence of oxygen. Commercial cytochrome P450 inhibitors including cytochrome c, SKF 525A, 1-aminobenzotriazole and ketoconazole also inhibited the enzyme activities. The present work presents unanimous enzymological evidence that cytochrome P450s are responsible for the synthesis of brassinolide from castasterone as well as of castasterone from typhasterol and 6-deoxocastasterone, which have been deemed activation steps of BRs.     

A novel murine long-chain acyl-CoA synthetase expressed in brain participates in neuronal cell proliferation

Refsum disease (RfD) is an autosomal recessive neurologic disorder of the lipid metabolism. We have identified a novel murine long-chain acyl-CoA synthetase (mLACS) associated with the RfD gene using yeast two-hybrid assay. Northern blot analyses revealed that mLACS was expressed mainly in the brain and testis. mLACS was highly expressed in the brain at 2 weeks after birth and maintained through adult life. Expressions of the brain-specific LACS family increased in the PC12 cells undergoing neurite outgrowth by nerve growth factor. mLACS preferentially catalyzed the formation of arachidonoyl-CoA more than palmitoyl-CoA or oleoyl-CoA in PC12 cells. Triacsin C, an inhibitor of LACS, suppressed the cell proliferation and decreased mLACS expression in parent PC12 cells, but not in stably anti-sense mLACS cDNA-transfected cells. Our results indicate that mLACS participates in neuronal cell proliferation and differentiation, and interaction of the RfD gene with brain-selective mLACS may be involved in the pathogenesis of RfD.     

Purification and characterization of complement-activating acidic polysaccharides from the fruits of Capsicum annuum

Hot water-soluble crude polysaccharide (HCAP-0) that was obtained from the fruits of Capsicum annuum showed potent anti-complementary activity. The activity was unchanged by pronase digestion, but decreased by periodate oxidation. The HCAP-0 was fractionated by DEAE ion-exchange chromatography to give two major fractions, HCAP-II and III. These two fractions were finally purified by gel filtration to give HCAP-IIa, HCAPIIIa1, and IIIa2 fractions that had high anti-complementary activities. The HCAP-IIIa1 and IIIa2 consisted of homogeneous polysaccharides. The anti-complementary activities were unaffected by treatment with polymyxin B, indicating that the modes of complement activation were not due to preexisting lipopolysaccharide. The molecular weight and sugar content of HCAP-IIIa2 had potent anti-complementary activity. The highest yields were 55 kDa and 75.9%, and the molar ratio of galactose (Ara:Gal, 1.0:4.6) was higher than other sugars. The crossed immuno-electrophoresis showed that both classical and alternative pathways were activated by HCAP-IIIa2.     

ATP stimulates glucose transport through activation of P2 purinergic receptors in C(2)C(12) skeletal muscle cells

Extracellular ATP acts as a signal that regulates a variety of cellular processes via binding to P2 purinergic receptors (P2 receptors). We herein investigated the effects and signaling pathways of ATP on glucose uptake in C(2)C(12) skeletal muscle cells. ATP as well as P2 receptor agonists (ATP-gamma S) stimulated the rate of glucose uptake, while P2 receptor antagonists (suramin) inhibited the stimulatory effect of ATP, indicating that P2 receptors are involved. This ATP-stimulated glucose transport was blocked by specific inhibitors of Gi protein (pertusiss toxin), phospholipase C (U73122), protein kinase C (GF109203X), and phosphatidylinositol (PI) 3-kinase (LY294002). ATP stimulated PI 3-kinase activity and P2 receptor antagonists blocked this activation. In C(2)C(12) myotubes expressing glucose transporter GLUT4, ATP increased basal and insulin-stimulated glucose transport. Finally, ATP facilitated translocation of GLUT1 and GLUT4 into plasma membrane. These results together suggest that cells respond to extracellular ATP to increase glucose transport through P2 receptors.