Biotransformation of dichloro-, trichloro-, and tetrachlorodibenzo-p-dioxin by the white-rot fungus Phlebia lindtneri

The model polychlorinated dibenzo-p-dioxins (PCDDs) 2,7-dichloro-, 2,3,7-trichloro, 1,2,6,7-, 1,2,8,9-, and 1,3,6,8-tetrachlorodibenzo-p-dioxin were used as substrates for a degradation experiment with the white-rot fungus Phlebia lindtneri. 2,7-Dichlorodibenzo-p-dioxin (2,7-diCDD) was biotransformed to hydroxylated diCDD and methoxylated diCDD. With the exception of 1,3,6,8-tetrachlorodibenzo-p-dioxin, the tri- and tetrachlorodibenzo-p-dioxins were biotransformed to hydroxyl and methoxyl compounds by P. lindtneri. The degradation rate of 1,2,6,7-tetrachlorodibenzo-p-dioxin was higher than that of 2,3,7-trichlorodibenzo-p-dioxin and no degradation of 1,3,6,8-tetrachlorodibenzo-p-dioxin was observed. These results indicate that the degradation of these PCDDs depends on the chlorination patterns of the substrates. This is the first report of the hydroxylation and methoxylation of tri- to tetra-CDDs by a fungal strain.     

New piperidinyl- and 1,2,3,6-tetrahydropyridinyl-pyrimidine derivatives as selective 5-HT1A receptor agonists with highly potent anti-ischemic effects

A series of new piperidinyl- and 1,2,3,6-tetrahydropyridinyl-pyrimidine derivatives were synthesized. Among these compounds, 4-methyl-2-(1,2,3,6-tetrahydropyridin-4-yl)pyrimidine derivative 23 (SUN N5147) exhibited sub-nanomolar affinity for 5-HT1A receptor with 1000-fold selectivity over both dopamine D2 and alpha1-adrenergic receptors and remarkable neuroprotective activity in a transient middle cerebral artery occlusion (t-MCAO) model.     

Reduced pain hypersensitivity and inflammation in mice lacking microsomal prostaglandin e synthase-1

We examined the in vivo role of membrane-bound prostaglandin E synthase (mPGES)-1, a terminal enzyme in the PGE2-biosynthetic pathway, using mPGES-1 knockout (KO) mice. Comparison of PGES activity in the membrane fraction of tissues from mPGES-1 KO and wild-type (WT) mice indicated that mPGES-1 accounted for the majority of lipopolysaccharide (LPS)-inducible PGES in WT mice. LPS-stimulated production of PGE2, but not other PGs, was impaired markedly in mPGES-1-null macrophages, although a low level of cyclooxygenase-2-dependent PGE2 production still remained. Pain nociception, as assessed by the acetic acid writhing response, was reduced significantly in KO mice relative to WT mice. This phenotype was particularly evident when these mice were primed with LPS, where the stretching behavior and the peritoneal PGE2 level of KO mice were far less than those of WT mice. Formation of inflammatory granulation tissue and attendant angiogenesis in the dorsum induced by subcutaneous implantation of a cotton thread were reduced significantly in KO mice compared with WT mice. Moreover, collagen antibody-induced arthritis, a model for human rheumatoid arthritis, was milder in KO mice than in WT mice. Collectively, our present results provide unequivocal evidence that mPGES-1 contributes to the formation of PGE2 involved in pain hypersensitivity and inflammation.     

Brain development in mice lacking L1-L1 homophilic adhesion

A new mouse line has been produced in which the sixth Ig domain of the L1 cell adhesion molecule has been deleted. Despite the rather large deletion, L1 expression is preserved at normal levels. In vitro experiments showed that L1-L1 homophilic binding was lost, along with L1-alpha5beta1 integrin binding. However, L1-neurocan and L1-neuropilin binding were preserved and sema3a responses were intact. Surprisingly, many of the axon guidance defects present in the L1 knockout mice, such as abnormal corticospinal tract and corpus callosum, were not observed. Nonetheless, when backcrossed on the C57BL/6 strain, a severe hydrocephalus was observed and after several generations, became an embryonic lethal. These results imply that L1 binding to L1, TAG-1, or F3, and L1-alpha5beta1 integrin binding are not essential for normal development of a variety of axon pathways, and suggest that L1-L1 homophilic binding is important in the production of X-linked hydrocephalus.     

Smad7 Inhibits Transforming Growth Factor-β Family Type I Receptors through Two Distinct Modes of Interaction

The inhibitory Smads (I-Smads), i.e. Smad6 and Smad7, are negative regulators of transforming growth factor-β (TGF-β) family signaling. I-Smads inhibit TGF-β family signaling principally through physical interaction with type I receptors (activin receptor-like kinases), so as to compete with receptor-regulated Smads (R-Smads) for activation. However, how I-Smads interact with type I receptors is not well understood. In the present study, we found that Smad7 has two modes of interaction with type I receptors. One is through a three-finger-like structure in the MH2 domain, consisting of residues 331–361, 379–387, and the L3 loop. The other is through a basic groove in the MH2 domain (Mochizuki, T., Miyazaki, H., Hara, T., Furuya, T., Imamura, T., Watabe, T., and Miyazono, K. (2004) J. Biol. Chem. 279, 31568–31574). We also found that Smad6 principally utilizes a basic groove in the MH2 domain for interaction with type I receptors. Smad7 thus has an additional mode of interaction with TGF-β family type I receptors not possessed by Smad6, which may play roles in mediating the inhibitory effects unique to Smad7.     

Effects of chlorogenic acid and its metabolites on spontaneous locomotor activity in mice

Chlorogenic acid possessed a weak caffeine-like psychostimulant property when assessed for its effect on spontaneous locomotor activity in mice. In the evaluation of the effects for the major metabolites of chlorogenic acid which were detected upon incubation with rat feces and/or excreted in urine after oral administration to rats, caffeic and m-coumaric acids were found to be the principal active metabolites, while the others contributed little to this caffeine-like psychostimulant activity.     

Overexpression of monocyte chemoattractant protein-1 in adipose tissues causes macrophage recruitment and insulin resistance

Adipose tissue expression and circulating concentrations of monocyte chemoattractant protein-1 (MCP-1) correlate positively with adiposity. To ascertain the roles of MCP-1 overexpression in adipose, we generated transgenic mice by utilizing the adipocyte P2 (aP2) promoter (aP2-MCP-1 mice). These mice had higher plasma MCP-1 concentrations and increased macrophage accumulation in adipose tissues, as confirmed by immunochemical, flow cytometric, and gene expression analyses. Tumor necrosis factor-alpha and interleukin-6 mRNA levels in white adipose tissue and plasma non-esterified fatty acid levels were increased in transgenic mice. aP2-MCP-1 mice showed insulin resistance, suggesting that inflammatory changes in adipose tissues may be involved in the development of insulin resistance. Insulin resistance in aP2-MCP-1 mice was confirmed by hyperinsulinemic euglycemic clamp studies showing that transgenic mice had lower rates of glucose disappearance and higher endogenous glucose production than wild-type mice. Consistent with this, insulin-induced phosphorylations of Akt were significantly decreased in both skeletal muscles and livers of aP2-MCP-1 mice. MCP-1 pretreatment of isolated skeletal muscle blunted insulin-stimulated glucose uptake, which was partially restored by treatment with the MEK inhibitor U0126, suggesting that circulating MCP-1 may contribute to insulin resistance in aP2-MCP-1 mice. We concluded that both paracrine and endocrine effects of MCP-1 may contribute to the development of insulin resistance in aP2-MCP-1 mice.     

Odd-skipped related 1 is required for development of the metanephric kidney and regulates formation and differentiation of kidney precursor cells

Formation of kidney tissue requires the generation of kidney precursor cells and their subsequent differentiation into nephrons, the functional filtration unit of the kidney. Here we report that the gene odd-skipped related 1 (Odd1) plays an important role in both these processes. Odd1 is the earliest known marker of the intermediate mesoderm, the precursor to all kidney tissue. It is localized to mesenchymal precursors within the mesonephric and metanephric kidney and is subsequently downregulated upon tubule differentiation. Mice lacking Odd1 do not form metanephric mesenchyme, and do not express several other factors required for metanephric kidney formation, including Eya1, Six2, Pax2, Sall1 and Gdnf. In transient ectopic expression experiments in the chick embryo, Odd1 can promote expression of the mesonephric precursor markers Pax2 and Lim1. Finally, persistent expression of Odd1 in chick mesonephric precursor cells inhibits differentiation of these precursors into kidney tubules. These data indicate that Odd1 plays an important role in establishing kidney precursor cells, and in regulating their differentiation into kidney tubular tissue.