Prostaglandin D2 plays an essential role in chronic allergic inflammation of the skin via CRTH2 receptor

PGD(2) plays roles in allergic inflammation via specific receptors, the PGD receptor designated DP and CRTH2 (chemoattractant receptor homologous molecule expressed on Th2 cells). We generated mutant mice carrying a targeted disruption of the CRTH2 gene to investigate the functional roles of CRTH2 in cutaneous inflammatory responses. CRTH2-deficent mice were fertile and grew normally. Ear-swelling responses induced by hapten-specific IgE were less pronounced in mutant mice, giving 35-55% of the responses of normal mice. Similar results were seen in mice treated with a hemopoietic PGD synthase inhibitor, HQL-79, or a CRTH2 antagonist, ramatroban. The reduction in cutaneous responses was associated with decreased infiltration of lymphocytes, eosinophils, and basophils and decreased production of macrophage-derived chemokine and RANTES at inflammatory sites. In models of chronic contact hypersensitivity induced by repeated hapten application, CRTH2 deficiency resulted in a reduction by approximately half of skin responses and low levels (63% of control) of serum IgE production, although in vivo migration of Langerhans cells and dendritic cells to regional lymph nodes was not impaired in CRTH2-deficient mice. In contrast, delayed-type hypersensitivity to SRBC and irritation dermatitis in mutant mice were the same as in wild-type mice. These findings indicate that the PGD(2)-CRTH2 system plays a significant role in chronic allergic skin inflammation. CRTH2 may represent a novel therapeutic target for treatment of human allergic disorders, including atopic dermatitis.     

Naturally arising CD4+CD25+ regulatory T cells suppress the expansion of colitogenic CD4+CD44highCD62L- effector memory T cells

Naturally arising CD4+CD25+ regulatory T (T(R)) cells have been shown to prevent and cure murine T cell-mediated colitis. However, their exact mechanism of controlling colitogenic memory CD4+ T cells in in vivo systems excluding the initial process of naive T cell activation and differentiation has not been examined to date. Using the colitogenic effector memory (T(EM)) CD4+ cell-mediated colitis model induced by adoptive transfer of colitogenic CD4+CD44(high)CD62L(-) lamina propria (LP) T cells obtained from colitic CD4+CD45RB(high) T cell-transferred mice, we have shown in the present study that CD4+CD25+ T(R) cells are able not only to suppress the development of colitis, Th1 cytokine production, and the expansion of colitogenic LP CD4+ T(EM) cells but also to expand these cells by themselves extensively in vivo. An in vitro coculture assay revealed that CD4+CD25+ T(R) cells proliferated in the presence of IL-2-producing colitogenic LP CD4+ T(EM) cells at the early time point (48 h after culture), followed by the acquisition of suppressive activity at the late time point (96 h after culture). Collectively, these data suggest the distinct timing of the IL-2-dependent expansion of CD4+CD25+ T(R) cells and the their suppressive activity on colitogenic LP CD4+ T(EM) cells.     

Crucial role of the small GTPase ARF6 in hepatic cord formation during liver development

The mammalian small GTPase ADP-ribosylation factor 6 (ARF6) plays important roles in a wide variety of cellular events, including endocytosis, actin cytoskeletal reorganization, and phosphoinositide metabolism. However, physiological functions for ARF6 have not previously been examined. Here, we described the consequence of ARF6 ablation in mice, which manifests most obviously in the context of liver development. Livers from ARF6-/- embryos are smaller and exhibit hypocellularity, due to the onset of midgestational liver cell apoptosis. Preceding the apoptosis, however, defective hepatic cord formation is observed; the liver cells migrate abnormally upon exiting the primordial hepatic epithelial sheet and clump rather than becoming dispersed. Consistent with this observation, the ability of hepatocyte growth factor/scatter factor (HGF) to induce hepatic cord-like structures from ARF6-/- fetal hepatocytes cultured in vitro in collagen gel matrix is impaired. Finally, we show that endogenous ARF6 in wild-type fetal hepatocytes is activated in response to HGF stimulation. These results provide evidence that ARF6 is an essential component in the signaling pathway coupling HGF signaling to hepatic cord formation.     

Isolation and characterization of a new Clostridium sp. that performs effective cellulosic waste digestion in a thermophilic methanogenic bioreactor

A methanogenic bioreactor that utilized wastepaper was developed and operated at 55 degrees C. Microbial community structure analysis showed the presence of a group of clostridia that specifically occurred during the period of high fermentation efficiency. To isolate the effective cellulose digester, the sludge that exhibited high fermentation efficiency was inoculated into a synthetic medium that contained cellulose powder as the sole carbon source and was successively cultivated. A comprehensive 16S rRNA gene sequencing study revealed that the enriched culture contained various clostridia that had diverse phylogenetic positions. The microorganisms were further enriched by successive cultivation with filter paper as the substrate, as well as the bait carrier. A resultant isolate, strain EBR45 (= Clostridium sp. strain NBRC101661), was a new member of the order Clostridiales phylogenetically and physiologically related to Clostridium thermocellum and Clostridium straminisolvens. Specific PCR-based monitoring demonstrated that strain EBR45 specifically occurred during the high fermentation efficiency period in the original methanogenic sludge. Strain EBR45 effectively digested office paper in its pure cultivation system with a synthetic medium.     

Renal elimination of p-aminohippurate (PAH) in response to three days of biliary obstruction in the rat. The role of OAT1 and OAT3

Pharmacokinetic studies of the drugs administered to subjects with mechanical cholestasis are scarce. The purpose of the present study was to examine the effects of bile duct ligation of 3 days (peak of elevation of serum bile acids and bilirubin) on the systemic and renal PAH clearance and on the expression of cortical renal OAT1 and OAT3 in a rat model. PAH is the prototypical substrate of the renal organic anion transport system. Male Wistar rats underwent a bile duct ligation (BDL rats). Pair-fed sham-operated rats served as controls. BDL rats displayed a significantly lower systemic PAH clearance. Renal studies revealed a reduction in the renal clearance and in the excreted and secreted load of PAH in BDL rats. The OAT1 protein expression in kidney homogenates was not modified, but it decreased in the basolateral membranes from BDL rats. In contrast, OAT3 abundance in both kidney cortex homogenates and in basolateral membranes increased by 3 days after the ligation. Immunocytochemical studies (light microscopic and confocal immunofluorescence microscopic analyses) confirmed the changes in the renal expression of these transport proteins. The present study demonstrates the key role of OAT1 expression in the impaired elimination of PAH after 3 days of obstructive cholestasis.     

CLP36 and RIL recruit α-actinin-1 to stress fibers and differentially regulate stress fiber dynamics in F2408 fibroblasts

CLP36 is a member of the ALP/Enigma protein family and has been shown to be localized to stress fibers in various cells. We previously reported that depletion of CLP36 caused loss of stress fibers in BeWo choriocarcinoma cells, but it remains unclear how CLP36 contributes to stress fiber formation. In this study, we generated CLP36-depleted F2408 fibroblasts and found that stress fibers showed abnormal non-oriented organization in these cells. In addition to CLP36, F2408 cells contained RIL, another ALP/Enigma protein, and we demonstrated that RIL could compensate for the role of CLP36 in stress fiber formation. CLP36 and RIL form a complex with α-actinin-1 and palladin. We found a strong correlation between loss of CLP36/RIL and failure of α-actinin-1 or palladin to localize on stress fibers. In addition, time lapse observation revealed that incorporation of RIL stabilizes stress fibers and that CLP36 influences the dynamic architecture of these fibers. Our findings indicate that CLP36 and RIL have a redundant role in the formation of stress fibers, but have different effects on stress fiber dynamics in F2408 cells.     

Nation-wide litter fall data from 21 forests of the Monitoring Sites 1000 Project in Japan

This data paper reports litter fall data collected in a network of 21 forest sites in Japan. This is the largest litter fall data set freely available in Japan to date. The network is a part of the Monitoring Sites 1000 Project launched by the Ministry of the Environment, Japan. It covers subarctic to subtropical climate zones and the four major forest types in Japan. Twenty-three permanent plots in which usually 25 litter traps were installed were established in old-growth or secondary natural forests. Litter falls were collected monthly from 2004, and sorted into leaves, branches, reproductive structures and miscellaneous. The data provide seasonal patterns and inter-annual dynamics of litter falls, and their geographical patterns, and offer good opportunities for meta-analyses and comparative studies among forests.     

Gut endoderm is involved in the transfer of left-right asymmetry from the node to the lateral plate mesoderm in the mouse embryo

In the mouse, the initial signals that establish left-right (LR) asymmetry are determined in the node by nodal flow. These signals are then transferred to the lateral plate mesoderm (LPM) through cellular and molecular mechanisms that are not well characterized. We hypothesized that endoderm might play a role in this process because it is tightly apposed to the node and covers the outer surface of the embryo, and, just after nodal flow is established, higher Ca(2+) flux has been reported on the left side near the node, most likely in the endoderm cells. Here we studied the role of endoderm cells in the transfer of the LR asymmetry signal by analyzing mouse Sox17 null mutant embryos, which possess endoderm-specific defects. Sox17(-/-) embryos showed no expression or significantly reduced expression of LR asymmetric genes in the left LPM. In Sox17 mutant endoderm, the localization of connexin proteins on the cell membrane was greatly reduced, resulting in defective gap junction formation, which appeared to be caused by incomplete development of organized epithelial structures. Our findings suggest an essential role of endoderm cells in the signal transfer step from the node to the LPM, possibly using gap junction communication to establish the LR axis of the mouse.