A novel dimethylsulfoxide reductase family of molybdenum enzyme, Idr, is involved in iodate respiration by Pseudomonas sp. SCT.

Pseudomonas sp. strain SCT is capable of using iodate (IO3 - ) as a terminal electron acceptor for anaerobic respiration. A possible key enzyme, periplasmic iodate reductase (Idr), was visualized by active staining on non-denaturing gel electrophoresis. Liquid chromatography-tandem mass spectrometry analysis revealed that at least four proteins, designated as IdrA, IdrB, IdrP1 , and IdrP2 , were involved in Idr. IdrA and IdrB were homologues of catalytic and electron transfer subunits of respiratory arsenite oxidase (Aio); however, IdrA defined a novel clade within the dimethylsulfoxide (DMSO) reductase family. IdrP1 and IdrP2 were closely related to each other and distantly related to cytochrome c peroxidase. The idr genes (idrABP 1 P 2 ) formed an operon-like structure, and their transcription was upregulated under iodate-respiring conditions. Comparative proteomic analysis also revealed that Idr proteins and high affinity terminal oxidases (Cbb3 and Cyd), various H2 O2 scavengers, and chlorite (ClO2 - ) dismutase-like proteins were expressed specifically or abundantly under iodate-respiring conditions. These results suggest that Idr is a respiratory iodate reductase, and that both O2 and H2 O2 are formed as by-products of iodate respiration. We propose an electron transport chain model of strain SCT, in which iodate, H2 O2 , and O2 are used as terminal electron acceptors.

Crucial roles of XCR1-expressing dendritic cells and the XCR1-XCL1 chemokine axis in intestinal immune homeostasis.

Intestinal immune homeostasis requires dynamic crosstalk between innate and adaptive immune cells. Dendritic cells (DCs) exist as multiple phenotypically and functionally distinct sub-populations within tissues, where they initiate immune responses and promote homeostasis. In the gut, there exists a minor DC subset defined as CD103(+)CD11b(-) that also expresses the chemokine receptor XCR1. In other tissues, XCR1(+) DCs cross-present antigen and contribute to immunity against viruses and cancer, however the roles of XCR1(+) DCs and XCR1 in the intestine are unknown. We showed that mice lacking XCR1(+) DCs are specifically deficient in intraepithelial and lamina propria (LP) T cell populations, with remaining T cells exhibiting an atypical phenotype and being prone to death, and are also more susceptible to chemically-induced colitis. Mice deficient in either XCR1 or its ligand, XCL1, similarly possess diminished intestinal T cell populations, and an accumulation of XCR1(+) DCs in the gut. Combined with transcriptome and surface marker expression analysis, these observations lead us to hypothesise that T cell-derived XCL1 facilitates intestinal XCR1(+) DC activation and migration, and that XCR1(+) DCs in turn provide support for T cell survival and function. Thus XCR1(+) DCs and the XCR1/XCL1 chemokine axis have previously-unappreciated roles in intestinal immune homeostasis.

Imaging of the cross-presenting dendritic cell subsets in the skin-draining lymph node.

Dendritic cells (DCs) are antigen-presenting cells specialized for activating T cells to elicit effector T-cell functions. Cross-presenting DCs are a DC subset capable of presenting antigens to CD8(+) T cells and play critical roles in cytotoxic T-cell-mediated immune responses to microorganisms and cancer. Although their importance is known, the spatiotemporal dynamics of cross-presenting DCs in vivo are incompletely understood. Here, we study the T-cell zone in skin-draining lymph nodes (SDLNs) and find it is compartmentalized into regions for CD8(+) T-cell activation by cross-presenting DCs that express the chemokine (C motif) receptor 1 gene, Xcr1 and for CD4(+) T-cell activation by CD11b(+) DCs. Xcr1-expressing DCs in the SDLNs are composed of two different populations: migratory (CD103(hi)) DCs, which immigrate from the skin, and resident (CD8α(hi)) DCs, which develop in the nodes. To characterize the dynamic interactions of these distinct DC populations with CD8(+) T cells during their activation in vivo, we developed a photoconvertible reporter mouse strain, which permits us to distinctively visualize the migratory and resident subsets of Xcr1-expressing DCs. After leaving the skin, migratory DCs infiltrated to the deep T-cell zone of the SDLNs over 3 d, which corresponded to their half-life in the SDLNs. Intravital two-photon imaging showed that after soluble antigen immunization, the newly arriving migratory DCs more efficiently form sustained conjugates with antigen-specific CD8(+) T cells than other Xcr1-expressing DCs in the SDLNs. These results offer in vivo evidence for differential contributions of migratory and resident cross-presenting DCs to CD8(+) T-cell activation.

Immune-mediated antitumor effect by type 2 diabetes drug, metformin.

Metformin, a prescribed drug for type 2 diabetes, has been reported to have anti-cancer effects; however, the underlying mechanism is poorly understood. Here we show that this mechanism may be immune-mediated. Metformin enabled normal but not T-cell-deficient SCID mice to reject solid tumors. In addition, it increased the number of CD8(+) tumor-infiltrating lymphocytes (TILs) and protected them from apoptosis and exhaustion characterized by decreased production of IL-2, TNFα, and IFNγ. CD8(+) TILs capable of producing multiple cytokines were mainly PD-1(-)Tim-3(+), an effector memory subset responsible for tumor rejection. Combined use of metformin and cancer vaccine improved CD8(+) TIL multifunctionality. The adoptive transfer of antigen-specific CD8(+) T cells treated with metformin concentrations as low as 10 µM showed efficient migration into tumors while maintaining multifunctionality in a manner sensitive to the AMP-activated protein kinase (AMPK) inhibitor compound C. Therefore, a direct effect of metformin on CD8(+) T cells is critical for protection against the inevitable functional exhaustion in the tumor microenvironment.

Critical roles of a dendritic cell subset expressing a chemokine receptor, XCR1.

Dendritic cells (DCs) consist of various subsets that play crucial roles in linking innate and adaptive immunity. In the murine spleen, CD8α(+) DCs exhibit a propensity to ingest dying/dead cells, produce proinflammatory cytokines, and cross-present Ags to generate CD8(+) T cell responses. To track and ablate CD8α(+) DCs in vivo, we generated XCR1-venus and XCR1-DTRvenus mice, in which genes for a fluorescent protein, venus, and a fusion protein consisting of diphtheria toxin receptor and venus were knocked into the gene locus of a chemokine receptor, XCR1, which is highly expressed in CD8α(+) DCs. In both mice, venus(+) cells were detected in the majority of CD8α(+) DCs, but they were not detected in any other cells, including splenic macrophages. Venus(+)CD8α(+) DCs were superior to venus(-)CD8α(+) DCs with regard to their cytokine-producing ability in response to TLR stimuli. In other tissues, venus(+) cells were found primarily in lymph node (LN)-resident CD8α(+), LN migratory and peripheral CD103(+) DCs, which are closely related to splenic CD8α(+) DCs, although some thymic CD8α(-)CD11b(-) and LN CD103(-)CD11b(-) DCs were also venus(+). In response to dsRNAs, diphtheria toxin-treated XCR1-DTR mice showed impaired CD8(+) T cell responses, with retained cytokine and augmented CD4(+) T cell responses. Furthermore, Listeria monocytogenes infection and anti-L. monocytogenes CD8(+) T cell responses were defective in diphtheria toxin-treated XCR1-DTRvenus mice. Thus, XCR1-expressing DCs were required for dsRNA- or bacteria-induced CD8(+) T cell responses. XCR1-venus and XCR1-DTRvenus mice should be useful for elucidating the functions and behavior of XCR1-expressing DCs, including CD8α(+) and CD103(+) DCs, in lymphoid and peripheral tissues.

HSP70 and HSP90 Differentially Regulate Translocation of Extracellular Antigen to the Cytosol for Cross-Presentation.

Antigens (Ag) from cancer or virus-infected cells must be internalized by dendritic cells (DCs) to be presented to CD8(+) T cells, which eventually differentiate into Ag-specific cytotoxic T lymphocytes (CTLs) that destroy cancer cells and infected cells. This pathway is termed cross-presentation and is also implicated as an essential step in triggering autoimmune diseases such as Type I diabetes. Internalized Ag locates within endosomes, followed by translocation through a putative pore structure spanning endosomal membranes into the cytosol, where it is degraded by the proteasome to generate antigen peptides. During translocation, Ag is believed to be unfolded since the pore size is too narrow to accept native Ag structure. Here, we show that paraformaldehyde-fixed, structurally inflexible Ag is less efficient in cross-presentation because of diminished translocation into the cytosol, supporting the "unfolded Ag" theory. We also show that HSP70 inhibitors block both endogenous and cross-presentation. ImageStream analysis revealed that the inhibition in cross-presentation is not due to blocking of Ag translocation because a HSP70 inhibitor rather facilitates the translocation, which is in marked contrast to the effect of an HSP90 inhibitor that blocks Ag translocation. Our results indicate that Ag translocation to the cytosol in cross-presentation is differentially regulated by HSP70 and HSP90.

Spi-B is critical for plasmacytoid dendritic cell function and development.

Plasmacytoid dendritic cells (pDCs), originating from hematopoietic progenitor cells in the BM, are a unique dendritic cell subset that can produce large amounts of type I IFNs by signaling through the nucleic acid-sensing TLR7 and TLR9 (TLR7/9). The molecular mechanisms for pDC function and development remain largely unknown. In the present study, we focused on an Ets family transcription factor, Spi-B, that is highly expressed in pDCs. Spi-B could transactivate the type I IFN promoters in synergy with IFN regulatory factor 7 (IRF-7), which is an essential transcription factor for TLR7/9-induced type I IFN production in pDCs. Spi-B-deficient pDCs and mice showed defects in TLR7/9-induced type I IFN production. Furthermore, in Spi-B-deficient mice, BM pDCs were decreased and showed attenuated expression of a set of pDC-specific genes whereas peripheral pDCs were increased; this uneven distribution was likely because of defective retainment of mature nondividing pDCs in the BM. The expression pattern of cell-surface molecules in Spi-B-deficient mice indicated the involvement of Spi-B in pDC development. The developmental defects of pDCs in Spi-B-deficient mice were more prominent in the BM than in the peripheral lymphoid organs and were intrinsic to pDCs. We conclude that Spi-B plays critical roles in pDC function and development.

Transcription of Vibrio parahaemolyticus T3SS1 genes is regulated by a dual regulation system consisting of the ExsACDE regulatory cascade and H-NS.

Vibrio parahaemolyticus, one of the human pathogenic vibrios, causes gastroenteritis, wound infections and septicemia. Genomic sequencing of this organism revealed that it has two distinct type III secretion systems (T3SS1 and T3SS2). T3SS1 plays a significant role in lethal activity in a murine infection model. It was reported that expression of the T3SS1 gene is controlled by a positive regulator, ExsA, and a negative regulator, ExsD, which share a degree of sequence similarity with Pseudomonas aeruginosa ExsA and ExsD, respectively. However, it is unknown whether T3SS1 is regulated by a mechanism similar to that demonstrated for P. aeruginosa, because functional analysis of VP1701, which is homologous to ExsC, is lacking and there is no ExsE homologue in the T3SS1 region. Here, we demonstrate that vp1701 and vp1702 are functional orthologues of exsC and exsE, respectively, of P. aeruginosa. VP1701 was required for the production of T3SS1-related proteins. VP1702 was a negative regulator for T3SS1-related protein production and was secreted by T3SS1. We also found that H-NS represses T3SS1-related gene expression by suppressing exsA gene expression. These findings indicate that the transcription of V. parahaemolyticus T3SS1 genes is regulated by a dual regulatory system consisting of the ExsACDE regulatory cascade and H-NS.

Conservation of a chemokine system, XCR1 and its ligand, XCL1, between human and mice.

Understanding dendritic cell (DC) subset functions should lead to the development of novel types of vaccine. Here we characterized expression of XC chemokine receptor 1 (XCR1) and its ligand, XCL1. Murine XCR1 was the only chemokine receptor selectively expressed in CD8alpha(+) conventional DCs. XCL1 was constitutively expressed in NK cells, which contribute to serum XCL1 levels. NK and CD8(+) T cells increased XCL1 production upon activation. These expression patterns were conserved in human blood cells, including the BDCA3(+) DC subset. Thus, in human and mice, certain DC subsets should be chemotactic towards NK or activated CD8(+) T cells through XCR1.

Statins, inhibitors of 3-hydroxy-3-methylglutaryl-coenzyme A reductase, function as inhibitors of cellular and molecular components involved in type I interferon production.

OBJECTIVE: Statins, which are used as cholesterol-lowering agents, have pleiotropic immunomodulatory properties. Although beneficial effects of statins have been reported in autoimmune diseases, the mechanisms of these immunomodulatory effects are still poorly understood. Type I interferons (IFNs) and plasmacytoid dendritic cells (PDCs) represent key molecular and cellular pathogenic components in autoimmune diseases such as systemic lupus erythematosus (SLE). Therefore, PDCs may be a specific target of statins in therapeutic strategies against SLE. This study was undertaken to investigate the immunomodulatory mechanisms of statins that target the IFN response in PDCs. METHODS: We isolated human blood PDCs by flow cytometry and examined the effects of simvastatin and pitavastatin on PDC activation, IFNalpha production, and intracellular signaling. RESULTS: Statins inhibited IFNalpha production profoundly and tumor necrosis factor alpha production modestly in human PDCs in response to Toll-like receptor ligands. The inhibitory effect on IFNalpha production was reversed by geranylgeranyl pyrophosphate and was mimicked by either geranylgeranyl transferase inhibitor or Rho kinase inhibitor, suggesting that statins exert their inhibitory actions through geranylgeranylated Rho inactivation. Statins inhibited the expression of phosphorylated p38 MAPK and Akt, and the inhibitory effect on the IFN response was through the prevention of nuclear translocation of IFN regulatory factor 7. In addition, statins had an inhibitory effect on both IFNalpha production by PDCs from SLE patients and SLE serum-induced IFNalpha production. CONCLUSION: Our findings suggest a specific role of statins in controlling type I IFN production and a therapeutic potential in IFN-related autoimmune diseases such as SLE.

Inhibitor of IkappaB kinase activity, BAY 11-7082, interferes with interferon regulatory factor 7 nuclear translocation and type I interferon production by plasmacytoid dendritic cells.

INTRODUCTION: Plasmacytoid dendritic cells (pDCs) play not only a central role in the antiviral immune response in innate host defense, but also a pathogenic role in the development of the autoimmune process by their ability to produce robust amounts of type I interferons (IFNs), through sensing nucleic acids by toll-like receptor (TLR) 7 and 9. Thus, control of dysregulated pDC activation and type I IFN production provide an alternative treatment strategy for autoimmune diseases in which type I IFNs are elevated, such as systemic lupus erythematosus (SLE). Here we focused on IkappaB kinase inhibitor BAY 11-7082 (BAY11) and investigated its immunomodulatory effects in targeting the IFN response on pDCs. METHODS: We isolated human blood pDCs by flow cytometry and examined the function of BAY11 on pDCs in response to TLR ligands, with regards to pDC activation, such as IFN-alpha production and nuclear translocation of interferon regulatory factor 7 (IRF7) in vitro. Additionally, we cultured healthy peripheral blood mononuclear cells (PBMCs) with serum from SLE patients in the presence or absence of BAY11, and then examined the inhibitory function of BAY11 on SLE serum-induced IFN-alpha production. We also examined its inhibitory effect in vivo using mice pretreated with BAY11 intraperitonealy, followed by intravenous injection of TLR7 ligand poly U. RESULTS: Here we identified that BAY11 has the ability to inhibit nuclear translocation of IRF7 and IFN-alpha production in human pDCs. BAY11, although showing the ability to also interfere with tumor necrosis factor (TNF)-alpha production, more strongly inhibited IFN-alpha production than TNF-alpha production by pDCs, in response to TLR ligands. We also found that BAY11 inhibited both in vitro IFN-alpha production by human PBMCs induced by the SLE serum and the in vivo serum IFN-alpha level induced by injecting mice with poly U. CONCLUSIONS: These findings suggest that BAY11 has the therapeutic potential to attenuate the IFN environment by regulating pDC function and provide a novel foundation for the development of an effective immunotherapeutic strategy against autoimmune disorders such as SLE.

Critical role of IkappaB Kinase alpha in TLR7/9-induced type I IFN production by conventional dendritic cells.

A plasmacytoid dendritic cell (DC) can produce large amounts of type I IFNs after sensing nucleic acids through TLR7 and TLR9. IkappaB kinase alpha (IKKalpha) is critically involved in this type I IFN production through its interaction with IFN regulatory factor-7. In response to TLR7/9 signaling, conventional DCs can also produce IFN-beta but not IFN-alpha in a type I IFN-independent manner. In this study, we showed that IKKalpha was required for production of IFN-beta, but not of proinflammatory cytokines, by TLR7/9-stimulated conventional DCs. Importantly, IKKalpha was dispensable for IFN-beta gene upregulation by TLR4 signaling. Biochemical analyses indicated that IKKalpha exerted its effects through its interaction with IFN regulatory factor-1. Furthermore, IKKalpha was involved in TLR9-induced type I IFN-independent IFN-beta production in vivo. Our results show that IKKalpha is a unique molecule involved in TLR7/9-MyD88-dependent type I IFN production through DC subset-specific mechanisms.

RMI1 deficiency in mice protects from diet and genetic-induced obesity.

The aim of this study is to discover and characterize novel energy homeostasis-related molecules. We screened stock mouse embryonic stem cells established using the exchangeable gene trap method, and examined the effects of deficiency of the target gene on diet and genetic-induced obesity. The mutant strain 0283, which has an insertion at the recQ-mediated genome instability 1 (RMI1) locus, possesses a number of striking features that allow it to resist metabolic abnormalities. Reduced RMI1 expression, lower fasting-blood glucose and a reduced body weight (normal diet) were observed in the mutant mice. When fed a high-fat diet, the mutant mice were resistant to obesity, and also showed improved glucose intolerance and reduced abdominal fat tissue mass and food intake. In addition, the mutants were also resistant to obesity induced by the lethal yellow agouti (A(y)) gene. Endogenous RMI1 genes were found to be up-regulated in the liver and adipose tissue of KK-A(y) mice. RMI1 is a component of the Bloom's syndrome gene helicase complex that maintains genome integrity and activates cell-cycle checkpoint machinery. Interestingly, diet-induced expression of E2F8 mRNA, which is an important cell cycle-related molecule, was suppressed in the mutant mice. These results suggest that the regulation of energy balance by RMI1 is attributable to the regulation of food intake and E2F8 expression in adipose tissue. Taken together, these findings demonstrate that RMI1 is a novel molecule that regulates energy homeostasis.

[Case of rapidly progressive glomerulonephritis with anti-glomerular basement membrane antibody in the course of MPO-ANCA-associated pachymeningitis].

A 56-year-old female developed rapidly progressive glomerulonephritis in the course of myeloperoxidase antineutrophil cytoplasmic antibody (MPO-ANCA)-associated pachymeningitis that had been found four years previously. On admission, her serum creatinine increased from 0.8 mg dL to 1.84 mg dL and to 3.66 mg dL every 3 to 4 weeks. Urinalysis revealed that urinary protein excretion was 1.25 g day and 3+ hematuria. MPO-ANCA titer was found to be 50 EU and anti-glomerular basement membrane (GBM) antibody was also elevated to as high as 174 EU. Renal pathology revealed cellular to fibrocellular crescents in 21 out of 23 glomeruli with interstitial inflammation and fibrosis. Immunohistochemistry with anti IgG antibody showed linear staining along the glomerular capillary walls. Following plasma exchange and methylprednisolone pulse therapy, oral prednisolone at a dose of 50 mg day was instituted, but without significant effect. Subsequent cyclophosphamide pulse therapy was effective, resulting in the stabilization of serum creatinine at 2 mg dL and disappearance of urine abnormalities. In addition, the MPO-ANCA titer and anti-GBM antibody titer of the patient decreased to within the normal range in one month and three months, respectively. Pulmonary lesions were not found throughout the course. Recently the emergence of anti-GBM antibody-associated crescentic glomemrulonephritis in the course of MPO-ANCA-associated vasculitis has increasingly been reported. Accumulation of such cases may unravel the pathogenesis of these diseases. one month and three months, respectively. Pulmonary lesions were not found throughout the course. Recently the emergence of anti-GBM antibody-associated crescentic glomemrulonephritis in the course of MPO-ANCA-associated vasculitis has increasingly been reported. Accumulation of such cases may unravel the pathogenesis of these diseases.

Daedalin A, a metabolite of Daedalea dickinsii, inhibits melanin synthesis in an in vitro human skin model.

The culture broth of Daedalea dickinsii was found to predominantly contain the tyrosinase inhibitor, (2R)-6-hydroxy-2-hydroxymethyl-2-methyl-2H-chromene, daedalin A (1). Ongoing research into bioactive metabolites resulted in the identification of two new 2H-chromenes, 6-hydroxy-5,7-dimethoxy-2,2-dimethyl-2H-chromene (3) and 6-hydroxy-2-hydroxymethyl-5-methoxy-2-methyl-2H-chromene (4), together with 6-hydroxy-2,2-dimethyl-2H-chromene (2). Comparative studies of isolated compounds 1-4 and related compounds (+/-)-1 and 1a-1c showed 1 to have the strongest tyrosinase inhibitory activity. These results suggest that the hydroxyl groups at positions 6 and 9 of 1 were important for the potent activity. A Lineweaver-Burk plot for a kinetic analysis indicates that 1 competed with L-tyrosine for tyrosinase. Compound 1 also suppressed melanogenesis in a human skin model (up to 49% at 2.8 micromol/tissue application) without affecting the cell viability. Compounds 1, 1b and 1c also showed 1,1-diphenyl-2-picrylhydrazyl (DPPH) radical scavenging activity comparable to that of alpha-tocopherol.

Plasma adiponectin: a predictor of coronary heart disease in hemodialysis patients--a Japanese prospective eight-year study.

BACKGROUND/AIM: Plasma adiponectin may play a protective role in the pathogenesis of cardiovascular disease in hemodialysis (HD) patients. We examined the effect of plasma adiponectin levels on the prognosis of the HD patients. METHODS: 68 HD patients (male:female = 38:30) were subjected to plasma adiponectin measurement in 1998 and followed up over 8 years. RESULTS: Plasma adiponectin concentrations differed between male and female patients (9.3 vs. 15.7 microg/ml). The plasma adiponectin concentration as a whole was positively correlated with serum high-density lipoprotein cholesterol and negatively with serum creatinine and waist circumference. During an 8-year follow-up, the cardiac events occurred in 7 of 38 men and in 10 of 30 women. Cox's proportional hazard model analysis in a stepwise manner revealed that coronary heart disease (CHD) was associated with intact parathyroid hormone concentration, age, and the presence of diabetes in men whereas plasma adiponectin concentration was the most powerful single predictor in women. The impact of the plasma adiponectin concentration was strengthened by Kaplan-Meier survival analysis. In the group with a lower plasma adiponectin concentration, CHD events were significantly increased in men (p = 0.043) and in women (p = 0.007). CONCLUSION: Plasma adiponectin concentration may predict CHD outcomes in HD patients.

Immunoadjuvant effects of polyadenylic:polyuridylic acids through TLR3 and TLR7.

Double-stranded RNA (dsRNA) is produced upon viral infection and can activate innate immunity. Polyinosinic:polycytidylic acids [poly(I:C)] is a synthetic mimetic of dsRNA and functions through an endosomal receptor, Toll-like receptor (TLR) 3 or cytosolic receptors. Another type of dsRNA, polyadenylic:polyuridylic acids [poly(A:U)], can also act as an immune adjuvant, but it remains unclear how it exhibits its adjuvant effects. Here, we have characterized the adjuvant effects of poly(A:U). Poly(A:U) could induce both IFN-alpha and IL-12p40 from murine bone marrow dendritic cells (DCs). Poly(A:U)-induced IFN-alpha production depended on a DC subset, plasmacytoid dendritic cell (pDC), and required TLR7. IL-12p40 was also produced by poly(A:U)-stimulated pDC in a TLR7-dependent manner. In addition to pDC, conventional dendritic cell (cDC) also produced IL-12p40 in response to poly(A:U). This IL-12p40 induction resulted from two cDC subsets, CD24(high) cDC and CD11b(high) cDC in a TLR3- and TLR7-dependent manner, respectively. In vivo injection of poly(A:U) with antigen led to clonal expansion of and IFN-gamma production from antigen-specific CD8(+) T cells. Consistent with the in vitro findings, TLR3 and TLR7 were required for the clonal T-cell expansion. Notably, TLR3, rather than TLR7, was critical for generating IFN-gamma-producing CD8(+) T cells. CD8(+) T-cell responses induced by poly(A:U) were independent of type I IFN signaling. Our results demonstrate that poly(A:U) functions as an in vivo immunoadjuvant mainly through TLR3 and TLR7.

A tyrosinase inhibitor, Daedalin A, from mycelial culture of Daedalea dickinsii.

A chromene-type compound, daedalin A (1), was isolated from mycelial culture broth of Daedalea dickinsii. Based on spectroscopic data, the structure of 1 was found to be (2R)-6-hydroxy-2-hydroxymethyl-2-methyl-2H-chromene. Daedalin A (1) strongly inhibited the activity of tyrosinase (IC(50): 194 muM). In addition, 1 also showed 1,1-diphenyl-2-picrylhydrazyl scavenging activity (IC(50): 16.9 microM) and superoxide anion scavenging activity (IC(50): 28.5 microM).

Abnormal development of the olfactory bulb and reproductive system in mice lacking prokineticin receptor PKR2.

Prokineticins, multifunctional secreted proteins, activate two endogenous G protein-coupled receptors PKR1 and PKR2. From in situ analysis of the mouse brain, we discovered that PKR2 is predominantly expressed in the olfactory bulb (OB). To examine the role of PKR2 in the OB, we created PKR1- and PKR2-gene-disrupted mice (Pkr1(-/-) and Pkr2(-/-), respectively). Phenotypic analysis indicated that not Pkr1(-/-)but Pkr2(-/-)mice exhibited hypoplasia of the OB. This abnormality was observed in the early developmental stages of fetal OB in the Pkr2(-/-) mice. In addition, the Pkr2(-/-) mice showed severe atrophy of the reproductive system, including the testis, ovary, uterus, vagina, and mammary gland. In the Pkr2(-/-) mice, the plasma levels of testosterone and follicle-stimulating hormone were decreased, and the mRNA transcription levels of gonadotropin-releasing hormone in the hypothalamus and luteinizing hormone and follicle-stimulating hormone in the pituitary were also significantly reduced. Immunohistochemical analysis revealed that gonadotropin-releasing hormone neurons were absent in the hypothalamus in the Pkr2(-/-) mice. The phenotype of the Pkr2(-/-) mice showed similarity to the clinical features of Kallmann syndrome, a human disease characterized by association of hypogonadotropic hypogonadism and anosmia. Our current findings demonstrated that physiological activation of PKR2 is essential for normal development of the OB and sexual maturation.