Asymmetric synthesis and biological evaluation of the enantiomeric isomers of the immunosuppressive FTY720-phosphate

A practical asymmetric synthesis of both enantiomers of the immunosuppressive FTY720-phosphate (2) was accomplished, and the enantiomers were pharmacologically evaluated. Several lipases showed considerable activity and enantioselectivity for O-acylation of N-acetyl FTY720 (3) or N-benzyloxycarbonyl FTY720 (7) in combination with vinyl acetate or benzyl vinyl carbonate as the acyl donors. The synthesis using the lipase-catalyzed acylation as the key step produced the enantiomerically pure (>99.5% ee) enantiomers of 2 in multigram quantities. (S)-Isomer of 2 had more potent binding affinities to S1P(1,3,4,5) and inhibitory activity on lymphocyte migration toward S1P than (R)-2, suggesting that (S)-isomer of 2 is responsible for the immunosuppressive activity after administration of 1. Severe bradycardia was observed in anesthetized rats when (S)-2 was administered intravenously, while (R)-2 had no clear effect on heart rate up to 0.3 mg/kg.     

De novo design and characterization of a helical hairpin eicosapeptide; emergence of an anion receptor in the linker region

De novo design of supersecondary structures is expected to provide useful molecular frameworks for the incorporation of functional sites as in proteins. A 21 residue long, dehydrophenylalanine-containing peptide has been de novo designed and its crystal structure determined. The apolar peptide folds into a helical hairpin supersecondary structure with two right-handed helices, connected by a tetraglycine linker. The helices of the hairpin interact with each other through a combination of C-H.O and N-H.O hydrogen bonds. The folding of the apolar peptide has been realized without the help of either metal ions or disulphide bonds. A remarkable feature of the peptide is the unanticipated occurrence of an anion binding motif in the linker region, strikingly similar in conformation and function to the "nest" motif seen in several proteins. The observation supports the view for the possible emergence of rudimentary functions over short sequence stretches in the early peptides under prebiotic conditions.     

Peroxygenase reactions catalyzed by cytochromes P450

Cytochromes P450 (P450s) catalyze monooxygenation of a wide range of less reactive organic molecules under mild conditions. By contrast with the general reductive oxygen activation pathway of P450s, an H₂O₂-shunt pathway does not require any supply of electrons and protons for the generation of a highly reactive intermediate (compound I). Because the low cost of H₂O₂ allows us to use it in industrial-scale synthesis, the H₂O₂-shunt pathway is an attractive process for monooxygenation reactions. This review focuses on the P450-catalyzed monooxygenation of organic molecules using H₂O₂ as the oxidant.     

Length of the dark period affects flower opening and the expression of circadian-clock associated genes as well as xyloglucan endotransglucosylase/hydrolase genes in petals of morning glory (Ipomoea nil)

Key message

We isolated differentially expressed and dark-responsive genes during flower development and opening in petals of morning glory.

Abstract

Flower opening usually depends on petal expansion and is regulated by both genetic and environmental factors. Flower opening in morning glory (Ipomoea nil) is controlled by the dark/light regime just prior to opening. Opening was normal after 8- or 12-h dark periods but progressed very slowly after a 4-h dark period or in continuous light. Four genes (InXTH1–InXTH4) encoding xyloglucan endotransglucosylase/hydrolases (XTHs) and three genes (InEXPA1–InEXPA3) encoding alpha-expansins (EXPAs) were isolated. The expression patterns of InXTH2, InXTH3, and InXTH4 in petals were closely correlated with the rate of flower opening controlled by the length of the dark period prior to opening, but those of the EXPA genes were not. The expression pattern of InXTH1 gene was closely correlated with petal elongation. Suppression subtractive hybridization was used to isolate dark-responsive genes accompanying flower opening. The expressions of ten isolated genes were associated with the length of the dark period prior to flower opening. One gene was highly homologous to Arabidopsis PSEUDO-RESPONSE REGULATOR7, which is associated with the circadian clock and phytochrome signaling; another to Arabidopsis REVEILLE1, which affects the output of the circadian clock. Other genes were related to light responses, plant hormone effects and signal transduction. The possible roles of these genes in regulation of flower opening are discussed.     

Role of long-chain acyl-coenzyme A synthetases in the regulation of arachidonic acid metabolism in interleukin 1β-stimulated rat fibroblasts

Acyl coenzyme A synthetase long-chain family members (ACSLs) are a family of enzymes that convert long-chain free fatty acids into their acyl-CoAs and play an important role in fatty acid metabolism. Here we show the role of ACSL isozymes in interleukin (IL)-1β-induced arachidonic acid (AA) metabolism in rat fibroblastic 3Y1 cells. Treatment of 3Y1 cells with triacsin C, an ACSL inhibitor, markedly enhanced the IL-1β-induced prostaglandin (PG) biosynthesis. Small interfering RNA-mediated knockdown of endogenous Acsl4 expression increased significantly the release of AA metabolites, including PGE₂, PGD₂, and PGF_2α, compared with replicated control cells, whereas knockdown of Acsl1 expression reduced the IL-1β-induced release of AA metabolites. Experiments with double knockdown of Acsl4 and intracellular phospholipase A₂ (PLA₂) isozymes revealed that cytosolic PLA₂α, but not calcium-independent PLA₂s, is involved in the Acsl4 knockdown-enhanced PG biosynthesis. Electrospray ionization mass spectrometry of cellular phospholipids bearing AA showed that the levels of some, if not all, phosphatidylcholine (PC) and phosphatidylinositol species in Acsl4 knockdown cells were decreased after IL-1β stimulation, while those in control cells were not so obviously decreased. In Acsl1 knockdown cells, the levels of some AA-bearing PC species were reduced even in the unstimulated condition. Collectively, these results suggest that Acsl isozymes play distinct roles in the control of AA remodeling in rat fibroblasts: Acsl4 acts as the first step of enzyme for AA remodeling following IL-1β stimulation, and Acsl1 is involved in the maintenance of some AA-containing PC species.     

Insulin binds to type V collagen with retention of mitogenic activity

The abilities of eight extracellular matrix proteins, fibronectin, vitronectin, laminin, and collagen types I, II, III, IV, and V to bind insulin were examined by binding studies with insulin conjugated with peroxidase. At a physiological pH and ionic strength, type V collagen bound to insulin most strongly. The other types of collagen, laminin, and vitronectin also bound insulin with affinity lower than that of type V collagen. The insulin-binding site of type V collagen was in a 30-kDa CNBr fragment of the alpha 1 (V) chain. Analysis of the amino acid sequence showed that this 30-kDa fragment was identical to the heparin-binding fragment of type V collagen. The insulin-binding sites of laminin and vitronectin were located in the A chain and in the heparin-binding domain, respectively. Insulin bound to type V collagen stimulated the synthesis of DNA by mouse mammary tumor MTD cells, indicating that bound insulin retained mitogenic activity.     

Environmental filters shaping angiosperm tree assembly along climatic and geographic gradients

Question

Global‐scale forest censuses provide an opportunity to understand diversification processes in woody plant communities. Based on the climatic or geographic filtering hypotheses associated with tropical niche conservatism and dispersal limitation, we analysed phylogenetic community structures across a wide range of biomes and evaluated to what extent region‐specific processes have influenced large‐scale diversity patterns of tree species communities across latitude or continent.

Location

Global.

Methods

We generated a data set of species abundances for 21,379 angiosperm woody plants in 843 plots worldwide. We calculated net relatedness index (NRI) for each plot, based on a single global species pool and regional species pools, and phylogenetic β‐diversity (PBD) between plots. Then, we explored the correlations of NRI with climatic and geographic variables, and clarified phylogenetic dissimilarity along geographic and climatic differences. We also compared these patterns for South America, Africa, the Indo‐Pacific, Australia, the Nearctic, Western Palearctic and Eastern Palearctic.

Results

NRI based on a global‐scale species pool was negatively associated with precipitation and positively associated with Quaternary temperature change. PBD was positively associated with geographic distance and precipitation difference between plots across tropical and extratropical biomes. Moreover, phylogenetic dissimilarity was smaller in extratropical regions than in regions including the tropics, although temperate forests of the Eastern Palearctic showed a greater dissimilarity within extratropical regions.

Conclusions

Our findings support predictions of the climatic and geographic filtering hypotheses. Climatic filtering (climatic harshness and paleoclimatic change) relative to tropical niche conservatism played a role in sorting species from the global species pool and shaped the large‐scale diversity patterns, such as the latitudinal gradient observed across continents. Geographic filtering associated with dispersal limitation substantially contributed to regional divergence of tropical/extratropical biomes among continents. Old, long‐standing geographic barriers and recent climatic events differently influenced evolutionary diversification of angiosperm tree communities in tropical and extratropical biomes.     

Characterization of a Chlamydia pneumoniae Strain Isolated from a 57-Year-Old Man

The isolation of Chlamydia pneumoniae, especially from elderly persons, is generally not easy. Recently, we succeeded in isolating a chlamydial strain, which was designated KKpn-15, from a 57-year-old man suffering from acute bronchitis. It was compared with well established strains of C. pneumoniae, C. trachomatis and C. psittaci, and its biological properties, such as the morphology of elementary bodies (EBs) and inclusions, and the immunochemistry of EB proteins, were investigated. Based on the results obtained in the present study, it was confirmed that the new chlamydial strain, KKpn-15, is a member of the C. pneumoniae strain and that the organisms of KKpn-15 are useful as an antigen for the serodiagnosis and epidemiology of C. pneumoniae infection.     

Augmented synthesis of beta-human atrial natriuretic polypeptide in human failing hearts

To elucidate the synthesis of atrial natriuretic polypeptide (ANP) in the failing heart, eighteen human right auricles obtained at cardiovascular surgery were studied. The concentration of alpha-human ANP-like immunoreactivity (alpha-hANP-LI) in human right auricles ranged from 13.8 to 593.5 micrograms/g, and the tissue alpha-hANP-LI concentration in severe congestive heart failure (CHF) (New York Heart Association (NYHA) functional class III or IV) was much higher than those in mild CHF of NYHA class I and class II. The alpha-hANP-LI in the human auricle consisted of 3 major components of ANP, gamma-human ANP (gamma-hANP), beta-human ANP (beta-hANP) and alpha-human ANP (alpha-hANP). The predominant component of alpha-hANP-LI was gamma-hANP in the mild CHF, whereas beta-hANP and/or alpha-hANP were prevailing in the severe CHF and, especially, beta-hANP was markedly increased in human failing hearts.