Plasmacytoid dendritic cells regulate Th cell responses through OX40 ligand and type I IFNs

Dendritic cells (DCs) show a functional plasticity in determining Th responses depending on their maturational stage or on maturational signals delivered to the DCs. Human plasmacytoid DCs (PDCs) can induce either Th1- or Th2-type immune responses upon exposure to viruses or IL-3, respectively. In this study we have investigated the Th-polarizing capacity of PDCs after short (24-h) or long (72-h) culture with stimuli and have assessed the expression and function of OX40 ligand (OX40L) in PDC-mediated Th polarization in addition to type I IFN-dependent responses. IL-3-treated PDCs expressed OX40L, but produced almost no IFN-alpha in response to T cell stimulation (CD40 ligand or T cell interaction), resulting in the preferential priming of Th2 cells through OX40L-dependent mechanisms. Meanwhile, PDCs were rapidly endowed by viral infection (Sendai virus) with a high potency to develop IFN-gamma-producing Th cells depending on their capacity to residually produce IFN-alpha. Although Sendai virus-stimulated PDCs simultaneously expressed OX40L in their maturational process, the Th1-inducing effect of endogenous type I IFNs may overcome and thus conceal the OX40L-dependent Th2 responses. However, during maturation in response to Sendai virus over the longer 72-h period, the expression level of OX40L was up-regulated, whereas the residual IFN-alpha-producing ability was down-regulated, and consequently, the PDCs with prolonged Sendai virus stimulation induced Th2 responses to some extent. Thus, PDCs have the distinct means to dictate an appropriate response to environmental stimuli.     

Higher plant RecA-like protein is homologous to RadA

A novel RecA-like protein, differing from Dmc1 and Rad51, was characterized in Oryza sativa L. cv. Nipponbare. Because the protein is homologous to bacterial RadA, the gene was designated OsRadA. The open reading frame was predicted to encode a 66kDa protein of 619 amino acid residues and was found in plants but not animals or yeast. OsRadA showed D-loop and single-stranded DNA-dependent ATPase activities. Gene expression was found to be high in meristematic tissues, and was localized in the nucleus. An RNAi mutant of Arabidopsis thaliana RadA (AtRadA) was sensitive to mutagenic agents such as UV and MMC, suggesting that RadA functions in DNA repair.     

Adenosine A2A receptor is involved in cell surface expression of A2B receptor

The A2A and A2B adenosine receptors (A2AR and A2BR) are implicated in many physiological processes. However, the mechanisms of their intracellular maturation and trafficking are poorly understood. In comparative studies of A2AR versus A2BR expression in transfected cells, we noticed that the levels of cell surface expression of A2BR were significantly lower than those of A2AR. A large portion of the A2BR was degraded by the proteasome. Studies of cell surface expression of A2BR chimeric molecules in transfectants suggested that A2BR does not have the dominant forward transport signal for export from the endoplasmic reticulum to the cell surface. A2BR surface expression was increased in A2BR chimeras where the A2BR carboxyl terminus (CT) was replaced or fused with the A2AR CT. Co-transfection of A2AR with A2BR enhanced surface expression of A2BR though the F(X)(6)LL motif in the A2AR CT. The requirements of A2AR expression for better A2BR cell surface expression was not only established in transfectants but also confirmed by observations of much lower levels of A2BR-induced intracellular cAMP accumulation in response to A2BR-activating ligand in splenocytes from A2AR(-/-) mice than in wild type mice. The results of mechanistic studies suggested that poor A2BR expression at the cell surface might be accounted for mainly by the lack of a dominant forward transport signal from the endoplasmic reticulum to the plasma membrane; it is likely that A2BR forms a hetero-oligomer complex for better function.     

Differential distribution of vanilloid receptors in the primary sensory neurons projecting to the dorsal skin and muscles

We examined transient receptor potential (TRP) V1 and TRPV2 expression in calcitonin gene-related peptide (CGRP) positive (+) primary sensory neurons projecting to the skin and skeletal muscles of the rat dorsum. Among the dorsal root ganglia at the levels from C2 to Th1, 34.9% of neurons projecting to the skin were positive for CGRP, and 32.6% or 21.6% of neurons projecting to the trapezius muscle or the longissimus muscle were positive for CGRP. Of the small CGRP+ neurons projecting to the skin, 53.5% were positive for TRPV1, 11.6% were positive for TRPV2. Of the small CGRP+ neurons projecting to the trapezius or the longissimus, 53.1 or 53.2% were positive for TRPV1, 8.8 or 8.3% were positive for TRPV2, respectively. In the periphery, 29.3% of CGRP+ nerve fibers were positive for TRPV1 in the skin, whereas 65.0 or 59.8% were positive in the trapezius or the longissimus. Therefore, the present study showed that the percentage of CGRP+ neurons projecting to the trapezius is higher than that to the longissimus, and that the co-localization percentage of CGRP and TRPV1 on the sensory nerves was also higher in the trapezius than in the longissimus and the skin.     

Assembly of a mixture of isomeric BChl c from Chlorobium limicola as determined by intermolecular 13C-13C dipolar correlations: coexistence of dimer-based and pseudo-monomer-based stackings

A mixture of bacteriochlorophyll (BChl) c isomers was extracted from the cells of Chlorobium limicola that were grown in the media of 13C-enriched and natural-abundance isotopic compositions. The magic-angle spinning 13C NMR proton-driven spin-diffusion spectra were recorded with mixing times of 50, 100, and 250 ms for two different kinds of in vitro aggregates, one consisting of pure [13C]BChl c and the other consisting of a 1:1 mixture of [13C]BChl c and [12C]BChl c; those peaks whose intensities were reduced to approximately 1/4 by this dilution were assigned to intermolecular 13C-13C dipolar correlation peaks. On the other hand, the nearest-neighbor intermolecular carbon-carbon close contacts with distances of 4-6 A were simulated, to predict observed correlation peaks, for six different models of BChl c assembly. They include weakly overlapped monomers forming structure 1 and structure 2, strongly overlapped dimers forming straight and inclined columns, and weakly overlapped dimers forming aligned and displaced layers. Comparison between the observed correlation peaks and the predicted carbon-carbon close contacts, for both the macrocycles and the side chains, led us to a conclusion that the weakly overlapped dimers forming displaced layers are most likely the assembly of the BChl c molecules in the aggregate.     

Association of the -112A>C polymorphism of the uncoupling protein 1 gene with insulin resistance in Japanese individuals with type 2 diabetes

The -112A>C polymorphism (rs10011540) of the gene for uncoupling protein 1 (UCP1) has been associated with type 2 diabetes mellitus in Japanese individuals. The aim of the present study was to investigate the effects of this polymorphism, as well as the well-known -3826A>G polymorphism (rs1800592), on clinical characteristics of type 2 diabetes. We determined the genotypes of the two polymorphisms in 93 Japanese patients with type 2 diabetes. Intramyocellular lipid content and hepatic lipid content (HLC) were measured by magnetic resonance spectroscopy. No significant differences in age, sex, BMI, or HbA1c level were detected between type 2 diabetic patients with the -112C allele and those without it. However, homeostasis model assessment for insulin resistance (p=0.0089) and HLC (p=0.012) was significantly greater in patients with the -112C allele. We did not detect an association of the -3826A>G polymorphism (rs1800592) of UCP1 gene with any measured parameters. These results suggest that insulin resistance caused by the -112C allele influences the susceptibility to type 2 diabetes.