Biochemical, structural, genetic, physiological, and pathophysiological features of lipocalin-type prostaglandin D synthase

Transcriptomic responses to functional feeds in Atlantic salmon (Salmo salar)

Functional feeds are diets that have positive effects on both health and growth promoting performance of the animals ingesting them, by supplying additional compounds above and beyond the basic nutritional requirements for animal growth alone. The most common additives used in aquaculture diets are probiotics, prebiotics, immunostimulants, vitamins and nucleotides. Inclusion of these components to fish diets can increase feed conversion efficiency and growth, as well as having positive effects on the fish immune system. This review discusses the results from previous studies on fish nutrition and includes a novel genomic approach, using microarray analysis, to elucidate nutritional responses in Atlantic salmon (Salmo salar) fed a newly developed functional feed health premix diet. The transcriptome analysis demonstrated that compared to the standard diet feeding with the functional feed had significant effects on biological processes in the liver. This resulted in a reduction of the expression of genes related to protein turnover, reduced circulating plasma proteins and a down regulation of genes involved in the immune response. These results suggest that the functional feed may infer a decrease in whole body metabolic demands, suppressing both protein turnover and whole body oxygen demand, as well as down regulating several genes involved in the innate immune system. Together these changes appear to result in less energy wastage in fish and an enhanced growth and performance.

Verification of male infertility biomarkers in seminal plasma by multiplex selected reaction monitoring assay

Seminal plasma is a promising biological fluid to use for noninvasive clinical diagnostics of male reproductive system disorders. To verify a list of prospective male infertility biomarkers, we developed a multiplex selected reaction monitoring assay and measured the relative abundance of 31 proteins in 30 seminal plasma samples from normal, nonobstructive azoospermia and post-vasectomy individuals. Median levels of some proteins were decreased by more than 100-fold in nonobstructive azoospermia or post-vasectomy samples, in comparison with normal samples. To follow up the most promising candidates and measure their concentrations in seminal plasma, heavy isotope-labeled internal standards were synthesized and used to reanalyze 20 proteins in the same set of samples. Concentrations of candidate proteins in normal seminal plasma were found in the range 0.1-1000 μg/ml but were significantly decreased in nonobstructive azoospermia and post-vasectomy. These data allowed us to select, for the first time, biomarkers to discriminate between normal, nonobstructive azoospermia, and post-vasectomy (simulated obstructive azoospermia) seminal plasma samples. Some testis-specific proteins (LDHC, TEX101, and SPAG11B) performed with absolute or nearly absolute specificities and sensitivities. Cell-specific classification of protein expression indicated that Sertoli or germ cell dysfunction, but not Leydig cell dysfunction, was observed in nonobstructive azoospermia seminal plasma. The proposed panel of biomarkers, pending further validation, could lead to a clinical assay that can eliminate the need for testicular biopsy to diagnose the category of male infertility, thus providing significant benefits to patients as well as decreased costs associated with the differential diagnosis of azoospermia.

Expression and localization of the iron-siderophore binding protein lipocalin 2 in the normal rat brain and after kainate-induced excitotoxicity

Lipocalin 2 (LCN2) is produced by mammalian hosts to bind bacterial siderophore and sequester free iron as part of an innate immune response, and could also play a role in tissue iron homeostasis, but thus far, little is known about its expression in the CNS. The present study was carried out to study the expression of the lipocalin in the normal rat brain and after neuronal injury induced by kainate (KA). Low levels of LCN2 mRNA and protein expression were detected in most regions of the normal brain except the olfactory bulb, brainstem and cerebellum. KA lesions resulted in damage to the hippocampus, leading to an early increase at three days and a sustained elevation in LCN2 mRNA level of 16-fold, and protein expression at 80-fold in the lesioned tissue compared to controls at 2 weeks post-KA injection. The sustained elevation in mRNA expression was not detected among other lipocalins surveyed using real-time RT-PCR - apoD, PGDS, Rbp4 and LCN5. Single and double immunostaining confirmed that LCN2 is present in astrocytes in the olfactory bulb, brainstem and cerebellum of the normal brain, and reactive astrocytes in the KA-lesioned hippocampus. In conclusion, the present study showed LCN2 to be present in select brain regions, and is upregulated in astrocytes after neuronal injury induced by kainate. We postulate that, as in the periphery, LCN2 may have a role in iron transport or trafficking in the CNS.

Hematopoietic-Prostaglandin D2 synthase through PGD2 production is involved in the adult ovarian physiology

Background

The prostaglandin D2 (PGD2) pathway is involved in numerous biological processes and while it has been identified as a partner of the embryonic sex determining male cascade, the roles it plays in ovarian function remain largely unknown. PGD2 is secreted by two prostaglandin D synthases (Pgds); the male-specific lipocalin (L)-Pgds and the hematopoietic (H)-Pgds.

Methods

To study the expression of the Pgds in the adult ovary, in situ hybridization were performed. Then, to evaluate the role of H-Pgds produced PGD2 in the ovarian physiology, adult female mice were treated with HQL-79, a specific inhibitor of H-Pgds enzymatic activity. The effects on expression of the gonadotrophin receptors FshR and LhR, steroidogenic genes Cyp11A1, StAR and on circulating progesterone and estradiol, were observed.

Results

We report the localization of H-Pgds mRNA in the granulosa cells from the primary to pre-ovulatory follicles. We provide evidence of the role of H-Pgds-produced PGD2 signaling in the FSH signaling through increased FshR and LhR receptor expression. This leads to the activation of steroidogenic Cyp11A1 and StAR gene expression leading to progesterone secretion, independently on other prostanoid-synthetizing mechanisms. We also identify a role whereby H-Pgds-produced PGD2 is involved in the regulation of follicular growth through inhibition of granulosa cell proliferation in the growing follicles.

Conclusions

Together, these results show PGD2 signaling to interfere with FSH action within granulosa cells, thus identifying an important and unappreciated role for PGD2 signaling in modulating the balance of proliferation, differentiation and steroidogenic activity of granulosa cells.

Isolation of lipocalin-type protein from rainbow trout seminal plasma and its localisation in the reproductive system

The lipocalin protein family is a large and diverse group of small extracellular proteins characterised by their ability to bind hydrophobic molecules. In the present study, we describe the isolation procedure for rainbow trout seminal plasma protein, characterised by a moderate migration rate during polyacrylamide gel electrophoresis, providing information regarding its basic features and immunohistochemical localisation. This protein was identified as a lipocalin-type protein (LTP). The molecular mass of LTP was found to be 18 848 Da and it was found to lack any carbohydrate components. Only a few Salmoniformes contain LTP in their seminal plasma. The abundance of LTP in the Sertoli and Leydig cells of the testes of the rainbow trout, as well as in secretory cells of the efferent duct, suggests that this protein is specific for rainbow trout milt, where it acts as a lipophilic carrier protein. Moreover, the specific localisation of LTP in the flagella of the spermatozoa suggests a role for LTP in sperm motility. Further experiments are necessary to identify the endogenous ligands for LTP in rainbow trout seminal plasma and to characterise the binding properties of this protein.

Is there a role for the nuclear receptor PPARγ in neuropsychiatric diseases?

The aetiology of psychiatric diseases such as depression or schizophrenia remains largely unknown, even though multiple theories have been proposed. Although monoamine theory is the cornerstone of available pharmacological therapies, relapses, incomplete control of symptoms or failure in treatment occur frequently. From an inflammatory/immune point of view, both entities share several common hallmarks in their pathophysiology, e.g. neuroendocrine/immune alterations, structural/functional abnormalities in particular brain areas, and cognitive deficits, suggesting a dysregulated inflammatory-related component of these diseases that better explains the myriad of symptoms presented by affected individuals. In this review we aimed to explore the role and relevance of inflammatory related lipids (prostanoids) derived from arachidonic acid metabolism by identification of new inflammatory markers and possible pharmacological/dietary modulation of these compounds, with the aim of improving some of the symptoms developed by individuals affected with psychiatric diseases (a critical review of basic and clinical studies about inflammatory-related arachidonic acid metabolism on neuropsychiatric diseases is included). As a specific candidate, one of these immunoregulatory lipids, the anti-inflammatory prostaglandin 15d-PGJ₂ and its nuclear receptor peroxisome proliferator-activated nuclear receptor (PPARγ) could be used as a biological marker for psychiatric diseases. In addition, its pharmacological activation can be considered as a multi-faceted therapeutic target due to its anti-inflammatory/antioxidant/anti-excitotoxic/pro-energetic profile, reported in some inflammatory-related scenarios (neurological and stress-related diseases). PPARs are activated by a great variety of compounds, the most relevant being the currently prescribed group of anti-diabetic drugs thiazolidinediones, and some cannabinoids (both endocannabinoids, phytocannabinoids or synthetic), as possible novel therapeutical strategy.

NMR assignment of 1H, 13C, and 15N resonances of rat lipocalin-type prostaglandin D synthase

Lipocalin-type prostaglandin D synthase (L-PGDS) acts as both a PGD(2)-synthesizing enzyme and an extracellular transporter for small lipophilic molecules. Here we report the backbone and side-chain resonance assignments of uniformly (15)N, (13)C labeled rat L-PGDS.

Study on association between genetic polymorphisms of haem oxygenase-1, tumour necrosis factor, cadmium exposure and malaria pathogenicity and severity

Background

Malaria is the most important public health problems in tropical and sub-tropical countries. Haem oxygenase (HO) enzyme and the pro-inflammatory cytokine tumour necrosis factor (TNF) have been proposed as one of the factors that may play significant role in pathogenicity/severity of malaria infection. HO is the enzyme of the microsomal haem degradation pathway that yields biliverdin, carbon monoxide, and iron. In this study, the association between malaria disease pathogenicity/severity and (GT)_n repeat polymorphism in the promoter region of the inducible HO-1 including the effect of cadmium exposure (potent inducer of HO-1 transcription) as well as polymorphism of TNF were investigated.

Methods

Blood samples were collected from 329 cases non-severe malaria with acute uncomplicated Plasmodium falciparum malaria (UM) and 80 cases with Plasmodium vivax malaria (VM), and 77 cases with severe or cerebral malaria (SM) for analysis of genetic polymorphisms of HO-1 and TNF and cadmium levels. These patients consisted of 123 (25.3%) Thai, 243 (50.0%) Burmese and 120 (24.7%) Karen who were present at Mae Sot General Hospital, Mae Sot, Tak Province, Thailand.

Results

The number of (GT)_n repeats of the HO-1 gene in all patients varied between 16 and 39 and categorized to short (S), medium (M) and long (L) GT_n repeats. The genotype of (GT)_n repeat of HO-1 was found to be significantly different among the three ethnic groups of patients. Significantly higher frequency of S/L genotype was found in Burmese compared with Thai patients, while significantly lower frequencies of S/S and M/L but higher frequency of M/M genotype was observed in Burmese compared with Karen patients. No significant association between HO-1 and TNF polymorphisms including the inducing effect of cadmium and malaria pathogenicity/severity was observed.

Conclusions

Difference in the expression of HO-1 genotype in different ethnic groups may contribute to different severity of malaria disease. With this limited sample size, the finding of the lack of association between malaria disease pathogenicity/severity genetic polymorphisms of HO-1 (GT)_n repeat as well as TNF observed in this study may not entirely exclude their possible link with malaria disease pathogenicity/severity. Further study in larger sample size is required.

Development and characterization of new inhibitors of the human and mouse hematopoietic prostaglandin D(2) synthases

The hematopoietic prostaglandin D(2) synthase has a proinflammatory effect in a range of diseases, including allergic asthma, where its product prostaglandin D(2) (PGD(2)) has a role in regulating many of the hallmark disease characteristics. Here we describe the development and characterization of a novel series of hematopoietic prostaglandin D(2) synthase inhibitors with potency similar to that of known inhibitors. Compounds N-benzhydryl-5-(3-hydroxyphenyl)thiophene-2-carboxamide (compound 8) and N-(1-amino-1-oxo-3-phenylpropan-2-yl)-6-(thiophen-2-yl)nicotinamide (compound 34) demonstrated low micromolar potency in the inhibition of the purified enzyme, while only 34 reduced Toll-like receptor (TLR) inducible PGD(2) production in both mouse primary bone marrow-derived macrophages and the human megakaryocytic cell line MEG-01S. Importantly, 34 demonstrated a greater selectivity for inhibition of PGD(2) synthesis versus other eicosanoids that lie downstream of PGH(2) (PGE(2) and markers of prostacyclin (6-keto PGF(1alpha)) and thromboxane (TXB(2))) when compared to the known inhibitors HQL-79 (compound 1) and 2-phenyl-5-(1H-pyrazol-3-yl)thiazole (compound 2). Compound 34 therefore represents a selective hematopoietic prostaglandin D(2) synthase inhibitor.

Neurochemical measures co-vary with personality traits: forensic psychiatric findings replicated in a general population sample

Neurobiological markers in cerebrospinal fluid (CSF) and in serum, previously found to co-vary with destructive personality traits in violent offenders, were explored in a general population sample of 21 patients undergoing knee surgery. Results on the Karolinska Scales of Personality (KSP) and the Temperament and Character Inventory (TCI) were compared with CSF/serum albumin ratios and serum concentrations of beta-trace protein (betaTP) (as markers for blood-brain barrier (BBB) permeability), to CSF/serum albumin ratios between the dopamine and serotonin metabolites homovanillic acid (HVA)/5-hydroxyindoleacetic acid (HIAA) and to CSF and serum ratios between activated thyroid hormone (T3) and its precursor T4. Serum betaTP concentrations correlated with CSF/serum albumin ratios (P=0.018), but not with preoperative serum creatinine concentrations. Serum betaTP correlated significantly with Monotony Avoidance and Impulsiveness; CSF HVA/5-HIAA ratios with Irritability and low Cooperativeness. The betaTP is a potential serum marker for the integrity of the BBB that does not necessitate lumbar puncture. Thyroid hormones did not correlate with personality traits. As reported in forensic psychiatric patients, aggressive, unempathic personality traits were thus associated with increased dopaminergic activity in relation to the serotonergic activity and impulsivity to increased BBB permeability also in a general population group.

Mutation analysis of violaxanthin de-epoxidase identifies substrate-binding sites and residues involved in catalysis

Plants are able to deal with variable environmental conditions; when exposed to strong illumination, they safely dissipate excess energy as heat and increase their capacity for scavenging reacting oxygen species. Both these protection mechanisms involve activation of the xanthophyll cycle, in which the carotenoid violaxanthin is converted to zeaxanthin by violaxanthin de-epoxidase, using ascorbate as the source of reducing power. In this work, following determination of the three-dimensional structure of the violaxanthin de-epoxidase catalytic domain, we identified the putative binding sites for violaxanthin and ascorbate by in silico docking. Amino acid residues lying in close contact with the two substrates were analyzed for their involvement in the catalytic mechanism. Experimental results supported the proposed substrate-binding sites and point to two residues, Asp-177 and Tyr-198, which are suggested to participate in the catalytic mechanism, based on complete loss of activity in mutant proteins. The role of other residues and the mechanistic similarity to aspartic proteases and epoxide hydrolases are discussed.

Lipocalin-type prostaglandin D synthase as a regulator of the retinoic acid signalling in melanocytes

Lipocalin-type prostaglandin D synthase (L-PGDS) catalyses the formation of prostaglandin D(2) (PGD(2)) and also functions as a transporter for lipophilic ligands, including all-trans retinoic acid (RA). Here, we show that human epidermal melanocytes produce and secrete L-PGDS and PGD(2) in culture medium, whereas L-PGDS is not expressed in human melanoma cell lines, HMV-II, SK-MEL-28, 624 mel and G361. Treatment with RA (1 or 10 microM) for 4 days decreased the proliferation of melanocytes (30% decrease), but not melanoma cells. We therefore isolated L-PGDS-expressing cell lines from 624 mel cells. Treatment with RA decreased the proliferation of L-PGDS-expressing cells by 20%, but not mock-transfected cell lines lacking L-PGDS expression. RA induced expression of a cyclin-dependent kinase inhibitor p21(Cip1) in L-PGDS-expressing cells, but not mock-transfected cells. Moreover, RA increased the transient expression of a reporter gene carrying the RA-responsive elements in L-PGDS-expressing cell lines (at least 5-fold activation), compared to the 2-fold activation in mock-transfected cell lines, suggesting that L-PGDS may increase the sensitivity to RA. Lastly, the knockdown of L-PGDS expression by RNA interference was associated with the restoration of the RA-mediated decrease in proliferation of human and mouse melanocytes. In conclusion, L-PGDS may fine-tune the RA signalling in melanocytes.

Beta-Trace Protein as a Marker of Renal Dysfunction in Patients with Chronic Kidney Disease: Comparison with Other Renal Markers

Beta-trace protein (BTP), also known as prostaglandin D synthase, is a low-molecular-mass protein which belongs to the lipocalin protein family. It was found to be increased in the serum of patients with renal diseases. The aim of this study was to compare the clinical usefulness of serum levels of beta-trace protein for the detection of renal dysfunction in patients with chronic kidney disease (CKD) with levels of other renal markers: creatinine, cystatin C and β2-microglobulin (B2M). The study included 134 patients with a wide range of renal dysfunction that encompassed all five CKD stages. Obtained data showed that beta-trace protein highly correlated (Spearman test) with creatinine (r = 0.890), cystatin C (r = 0.904) and B2M (r = 0.933) and its levels in serum significantly increased from CKD stage 1 to 5. Furthermore, the values of glomerular filtration rate (GFR) estimated from a BTP-based formula significantly correlated with GFR calculated from creatinine-based and cystatin C-based formulas. ROC analyses showed that BTP had similar diagnostic accuracy for detection of reduced renal function in CKD stages as other renal markers, for estimated GFRs of < 30, < 60 and < 90 mL/min/1.73 m2. The areas under the ROC curves (AUC) for BTP, for these GFR limits, were from 0.983 to 0.917 and they were not significantly different from AUCs for other renal markers. The results of this study showed that BTP may be a useful and reliable serum marker for identifying the magnitude of renal dysfunction in patients with CKD and may have its place beside serum cystatin C and creatinine as an alternative endogenous GFR marker.

Possible role of heme oxygenase-1 and prostaglandins in the pathogenesis of cerebral malaria: heme oxygenase-1 induction by prostaglandin D(2) and metabolite by a human astrocyte cell line

Astrocytes are the most abundant cells in the central nervous system that play roles in maintaining the blood-brain-barrier and in neural injury, including cerebral malaria, a severe complication of Plasmodium falciparum infection. Prostaglandin (PG) D(2) is abundantly produced in the brain and regulates the sleep response. Moreover, PGD(2) is a potential factor derived from P. falciparum within erythrocytes. Heme oxygenase-1 (HO-1) is catalyzing enzyme in heme breakdown process to release iron, carbon monoxide, and biliverdin/bilirubin, and may influence iron supply to the P. falciparum parasites. Here, we showed that treatment of a human astrocyte cell line, CCF-STTG1, with PGD(2) significantly increased the expression levels of HO-1 mRNA by RT-PCR. Western blot analysis showed that PGD(2) treatment increased the level of HO-1 protein, in a dose- and time-dependent manner. Thus, PGD(2) may be involved in the pathogenesis of cerebral malaria by inducing HO-1 expression in malaria patients.

Measuring vs estimating glomerular filtration rate in kidney transplantation

Evaluation of kidney function is crucial in the care of kidney transplant recipients and in the design and interpretation of clinical trials in transplantation. Kidney function is most commonly assessed in both instances using serum creatinine concentration or an estimate of glomerular filtration rate (GFR) based on serum creatinine. These are inexpensive, widely available, and easily administered. Both have significant drawbacks, notably with respect to their inability to accurately identify changes in GFR. Novel markers of GFR such as cystatin C and beta-trace protein show promise as accurate and sensitive markers of GFR but have not yet been adequately evaluated in kidney transplantation. In addition, they are relatively expensive compared to creatinine and their assays are not available in most clinical laboratories. Glomerular filtration rate measurement using a variety of different available tracers and techniques is infrequently used in either clinical care or research protocols because of its cost and cumbersomeness. This review will discuss the merits and pitfalls of the various tools available to evaluate GFR in kidney transplantation.

Characterization of Nitrotyrosine-Modified Proteins in Cerebrospinal Fluid

Background

HIV-associated neurocognitive disorders (HAND) has been associated with the up-regulation of various oxidative stress pathways. Previous studies have linked the neuronal damage observed in individuals diagnosed with HAND to increased nitrotyrosine modification of neuronal proteins.

Materials and methods

Tyrosine nitration alters protein structure and function, affects biological half-life, and potentially prevents the phosphorylation of key tyrosine residues involved in signal transduction pathways. Therefore, in this study we employed proteomics-based experimental approaches to investigate nitrotyrosine-modified proteins in pooled cerebrospinal fluid (CSF) of individuals diagnosed with HAND. To identify specific nitrotyrosine-modified proteins in the CSF of individuals diagnosed with HAND, affinity purification and high-performance tandem mass spectrometry are utilized in a “bottom-up” proteomics approach.

Results

From tandem mass spectrometric analysis, we identified major proteins that underwent nitration as a result of nitro-oxidative stress in the CSF of individuals diagnosed with HAND. We also utilized analytical and biochemical techniques to characterize the expression and modification site of in vivo nitrated lipocalin-type prostaglandin-D synthase in HAND CSF.

Genetic mechanisms underlying male sex determination in mammals

Genetic control of gonadal development proceeds through either the male or female molecular pathways, driving bipotential gonadal anlage differentiation into a testis or ovary. Antagonistic interactions between the 2 pathways determine the gonadal sex. Essentially sex determination is the enhancement of one of the 2 pathways according to genetic sex. Initially, Sry with other factors upregulates Sox9 expression in XY individuals. Afterwards the expression of Sox9 is maintained by a positive feedback loop with Fgf9 and prostaglandin D2 as well as by autoregulative ability of Sox9. If these factors reach high concentrations, then Sox9 and/or Fgf9 may inhibit the female pathway. Surprisingly, splicing, nuclear transport, and extramatrix proteins may be involved in sex determination. The male sex determination pathway switches on the expression of genes driving Sertoli cell differentiation. Sertoli cells orchestrate testicular differentiation. In the absence of Sry, the predomination of the female pathway results in the realization of a robust genetic program that drives ovarian differentiation.

Endogenous N-acyl-dopamines induce COX-2 expression in brain endothelial cells by stabilizing mRNA through a p38 dependent pathway

Cerebral microvascular endothelial cells play an active role in maintaining cerebral blood flow, microvascular tone and blood brain barrier (BBB) functions. Endogenous N-acyl-dopamines like N-arachidonoyl-dopamine (NADA) and N-oleoyl-dopamine (OLDA) have been recently identified as a new class of brain neurotransmitters sharing endocannabinoid and endovanilloid biological activities. Endocannabinoids are released in response to pathogenic insults and may play an important role in neuroprotection. In this study we demonstrate that NADA differentially regulates the release of PGE(2) and PGD(2) in the microvascular brain endothelial cell line, b.end5. We found that NADA activates a redox-sensitive p38 MAPK pathway that stabilizes COX-2 mRNA resulting in the accumulation of the COX-2 protein, which depends on the dopamine moiety of the molecule and that is independent of CB(1) and TRPV1 activation. In addition, NADA inhibits the expression of mPGES-1 and the release of PGE(2) and upregulates the expression of L-PGD synthase enhancing PGD(2) release. Hence, NADA and other molecules of the same family might be included in the group of lipid mediators that could prevent the BBB injury under inflammatory conditions and our findings provide new mechanistic insights into the anti-inflammatory activities of NADA in the central nervous system and its potential to design novel therapeutic strategies to manage neuroinflammatory diseases.

RUNX2 transcription factor regulates gene expression in luteinizing granulosa cells of rat ovaries

The LH surge promotes terminal differentiation of follicular cells to become luteal cells. RUNX2 has been shown to play an important role in cell differentiation, but the regulation of Runx2 expression and its function in the ovary remain to be determined. The present study examined 1) the expression profile of Runx2 and its partner CBFbeta during the periovulatory period, 2) regulatory mechanisms of Runx2 expression, and 3) its potential function in the ovary. Runx2 expression was induced in periovulatory granulosa cells of human and rodent ovaries. RUNX2 and core binding factor-beta (CBFbeta) proteins in nuclear extracts and RUNX2 binding to a consensus binding sequence increased after human chorionic gonadotropin (hCG) administration. This in vivo up-regulation of Runx2 expression was recapitulated in vitro in preovulatory granulosa cells by stimulation with hCG. The hCG-induced Runx2 expression was reduced by antiprogestin (RU486) and EGF-receptor tyrosine kinase inhibitor (AG1478), indicating the involvement of EGF-signaling and progesterone-mediated pathways. We also found that in the C/EBPbeta knockout mouse ovary, Runx2 expression was reduced, indicating C/EBPbeta-mediated expression. Next, the function of RUNX2 was investigated by suppressing Runx2 expression by small interfering RNA in vitro. Runx2 knockdown resulted in reduced levels of mRNA for Rgc32, Ptgds, Fabp6, Mmp13, and Abcb1a genes. Chromatin immunoprecipitation analysis demonstrated the binding of RUNX2 in the promoter region of these genes, suggesting that these genes are direct downstream targets of RUNX2. Collectively, the present data indicate that the LH surge-induced RUNX2 is involved in various aspects of luteal function by directly regulating the expression of diverse luteal genes.

The CO-releasing molecule CORM-3 protects against articular degradation in the K/BxN serum transfer arthritis model

Carbon monoxide-releasing molecules can counteract inflammatory responses. The aim of this study was to investigate whether tricarbonylchloro(glycinate)ruthenium (II) (CORM-3) is able to control the effector phase of experimental arthritis. Arthritis was induced in C57Black-6 mice by an intraperitoneal injection of serum from arthritic K/BxN mice. CORM-3 was administered intraperitoneally at 10 mg/kg/day (5 mg/kg twice a day) from days 0 to 10 and animals were sacrificed on day 11. Serum levels of osteocalcin and prostanoids were measured by enzyme-linked immunosorbent assay and radioimmunoassay. Gene expression was determined by real-time PCR. Histological analysis was performed and protein expression was examined by immunohistochemistry. Treatment with CORM-3 reduced the macroscopic score in hind paws, the migration of inflammatory cells and erosion of cartilage and bone. CORM-3 increased the levels of osteocalcin in the serum and reduced PGD2 levels, whereas PGE2 and 6-ketoPGF1alpha were not affected. In synovial tissues, we also observed a significant reduction in gene expression of interleukin-1beta, receptor activator of nuclear factor kappaB ligand (RANKL), matrix metalloproteinase (MMP)-9 and MMP-13. CORM-3 induced HO-1 expression in joint tissues but inhibited high mobility group box 1 (HMGB1), hematopoietic-prostaglandin D2 synthase (H-PGDS) and lipocalin-type prostaglandin D2 synthase (L-PGDS), as well as RANKL and intercellular adhesion molecule-1. COX-2 expression was not affected by CORM-3 treatment. We have shown that CORM-3 decreases the inflammatory response and protects against the degradation of cartilage and bone in the arthritic mice. Pharmacological CO delivery represents a novel strategy to regulate the effector phase of arthritis.

N-acetylcysteine does not prevent hepatorenal ischaemia-reperfusion injury in patients undergoing orthotopic liver transplantation

BACKGROUND

Glutathione (GSH) acts as a free radical scavenger that may be helpful in preventing reperfusion injury. N-acetylcysteine (NAC) replenishes GSH stores. The aims of this study were to evaluate the efficacy of NAC in improving liver graft performance and reducing the incidence of post-operative acute kidney injury (AKI).

METHODS

Our study was a randomized, double-blind, placebo-controlled trial of 100 patients; 50 received placebo and 50 received a loading dose of 140 mg/kg of intravenous (IV) NAC over 1 h followed by 70 mg/kg IV repeated every 4 h for a total of 12 doses. Both groups were followed up for 1 year post-orthotopic liver transplant (OLT). We recorded liver function tests, renal function tests, graft survival, patient survival, plasma GSH and duration of hospital and ICU stay. In addition to serum creatinine (SCr) levels, we analysed cystatin C and beta-trace as independent measures of glomerular filtration. All clinical data were recorded daily for the first week after the surgery, then on Days 14, 21, 30, 90 and 180 and at the end of the first year.

RESULTS

IV NAC did not affect survival, graft function or risk of AKI. However, GSH levels were highly variable with only 50% of patients receiving NAC exhibiting increased levels and fewer patients developed AKI when GSH levels were increased. Additional risk factors for AKI in the post-transplant period were female gender (P = 0.05), increased baseline serum bilirubin (P = 0.004) and increased baseline SCr levels (P = 0.02).

CONCLUSIONS

IV NAC was not effective in reducing renal or hepatic injury in the setting of liver transplantation. The dose and duration of NAC used, though higher than most renal protection studies, may have been ineffective for raising GSH levels in some patients.

Pronounced adipogenesis and increased insulin sensitivity caused by overproduction of prostaglandin D2 in vivo

Lipocalin-type prostaglandin (PG) D synthase is expressed in adipose tissues and involved in the regulation of glucose tolerance and atherosclerosis in type 2 diabetes. However, the physiological roles of PGD(2) in adipogenesis in vivo are not clear, as lipocalin-type prostaglandin D synthase can also act as a transporter for lipophilic molecules, such as retinoids. We generated transgenic (TG) mice overexpressing human hematopoietic PGDS (H-PGDS) and investigated the in vivo functions of PGD(2) in adipogenesis. PGD(2) production in white adipose tissue of H-PGDS TG mice was increased approximately seven-fold as compared with that in wild-type (WT) mice. With a high-fat diet, H-PGDS TG mice gained more body weight than WT mice. Serum leptin and insulin levels were increased in H-PGDS TG mice, and the triglyceride level was decreased by about 50% as compared with WT mice. Furthermore, in the white adipose tissue of H-PGDS TG mice, transcription levels of peroxisome proliferator-activated receptor gamma, fatty acid binding protein 4 and lipoprotein lipase were increased approximately two-fold to five-fold as compared with those of WT mice. Finally, H-PGDS TG mice showed clear hypoglycemia after insulin clamp. These results indicate that TG mice overexpressing H-PGDS abundantly produced PGD(2) in adipose tissues, resulting in pronounced adipogenesis and increased insulin sensitivity. The present study provides the first evidence that PGD(2) participates in the differentiation of adipocytes and in insulin sensitivity in vivo, and the H-PGDS TG mice could constitute a novel model mouse for diabetes studies.

On the mechanism of microsomal prostaglandin E synthase type-2--a theoretical study of endoperoxide reaction with MeS(-)

The reaction pathways of deprotonation versus nucleophilic substitution involving mPGES-2 enzyme catalysis were investigated by ab initio molecular orbital theory calculations for the reaction of methylthiolate with the endoperoxide core of PGH(2) and by the combined quantum mechanical molecular mechanical methods. The calculations showed that deprotonation mechanism is energetically more favorable than the nucleophilic substitution pathway.

Identification and characterisation of new inhibitors for the human hematopoietic prostaglandin D2 synthase

Prostaglandin D(2) synthesised by the hematopoietic prostaglandin D(2) synthase has a pro-inflammatory effect in allergic asthma, regulating many hallmark characteristics of the disease. Here we describe identification of hematopoietic prostaglandin D(2) synthase inhibitors including cibacron blue, bromosulfophthalein and ethacrynic acid. Expansion around the drug-like ethacrynic acid identified a novel inhibitor, nocodazole, and a fragment representing its aromatic core. Nocodazole binding was further characterised by docking calculations in combination with conformational strain analysis. The benzyl thiophene core was predicted to be buried in the active site, binding in the putative prostaglandin binding site, and a likely hydrogen bond donor site identified. X-ray crystallographic studies supported the predicted binding mode.

Structural analysis of lipocalin-type prostaglandin D synthase complexed with biliverdin by small-angle X-ray scattering and multi-dimensional NMR

Lipocalin-type prostaglandin D synthase (L-PGDS) acts as both a PGD(2) synthase and an extracellular transporter for small lipophilic molecules. From a series of biochemical studies, it has been found that L-PGDS has an ability to bind a variety of lipophilic ligands such as biliverdin, bilirubin and retinoids in vitro. Therefore, we considered that it is necessary to clarify the molecular structure of L-PGDS upon binding ligand in order to understand the physiological relevance of L-PGDS as a transporter protein. We investigated a molecular structure of L-PGDS/biliverdin complex by small-angle X-ray scattering (SAXS) and multi-dimensional NMR measurements, and characterized the binding mechanism in detail. SAXS measurements revealed that L-PGDS has a globular shape and becomes compact by 1.3A in radius of gyration on binding biliverdin. NMR experiments revealed that L-PGDS possessed an eight-stranded antiparallel beta-barrel forming a central cavity. Upon the titration with biliverdin, some cross-peaks for residues surrounding the cavity and EF-loop and H2-helix above the beta-barrel shifted, and the intensity of other cross-peaks decreased with signal broadenings in (1)H-(15)N heteronuclear single quantum coherence spectra. These results demonstrate that L-PGDS holds biliverdin within the beta-barrel, and the conformation of the loop regions above the beta-barrel changes upon binding biliverdin. Through such a conformational change, the whole molecule of L-PGDS becomes compact.

What are melanocytes really doing all day long...?

Everyone knows and seems to agree that melanocytes are there to generate melanin - an intriguing, but underestimated multipurpose molecule that is capable of doing far more than providing pigment and UV protection to skin (1). What about the cell that generates melanin, then? Is this dendritic, neural crest-derived cell still serving useful (or even important) functions when no-one looks at the pigmentation of our skin and its appendages and when there is essentially no UV exposure? In other words, what do epidermal and hair follicle melanocytes do in their spare time - at night, under your bedcover? How much of the full portfolio of physiological melanocyte functions in mammalian skin has really been elucidated already? Does the presence or absence of melanocytes matter for normal epidermal and/or hair follicle functions (beyond pigmentation and UV protection), and for skin immune responses? Do melanocytes even deserve as much credit for UV protection as conventional wisdom attributes to them? In which interactions do these promiscuous cells engage with their immediate epithelial environment and who is controlling whom? What lessons might be distilled from looking at lower vertebrate melanophores and at extracutaneous melanocytes in the endeavour to reveal the 'secret identity' of melanocytes? The current Controversies feature explores these far too infrequently posed, biologically and clinically important questions. Complementing a companion viewpoint essay on malignant melanocytes (2), this critical re-examination of melanocyte biology provides a cornucopia of old, but under-appreciated concepts and novel ideas on the slowly emerging complexity of physiological melanocyte functions, and delineates important, thought-provoking questions that remain to be definitively answered by future research.

Structural basis of the catalytic mechanism operating in open-closed conformers of lipocalin type prostaglandin D synthase

Lipocalin type prostaglandin D synthase (L-PGDS) is a multifunctional protein acting as a somnogen (PGD2)-producing enzyme, an extracellular transporter of various lipophilic ligands, and an amyloid-beta chaperone in human cerebrospinal fluid. In this study, we determined the crystal structures of two different conformers of mouse L-PGDS, one with an open cavity of the beta-barrel and the other with a closed cavity due to the movement of the flexible E-F loop. The upper compartment of the central large cavity contains the catalytically essential Cys65 residue and its network of hydrogen bonds with the polar residues Ser45, Thr67, and Ser81, whereas the lower compartment is composed of hydrophobic amino acid residues that are highly conserved among other lipocalins. SH titration analysis combined with site-directed mutagenesis revealed that the Cys65 residue is activated by its interaction with Ser45 and Thr67 and that the S45A/T67A/S81A mutant showed less than 10% of the L-PGDS activity. The conformational change between the open and closed states of the cavity indicates that the mobile calyx contributes to the multiligand binding ability of L-PGDS.

L-PGDS (betatrace protein) inhibits astrocyte proliferation and mitochondrial ATP production in vitro

L-PGDS is the most abundant protein present in the cerebrospinal fluid (CSF). Although CSF was believed to be homogenous in content, a previous study has showed that a marked concentration gradient of L-PGDS exists between the spinal CSF and the CSF in the subarachnoid space of patients with optic nerve disease (papilledema and normal-tension glaucoma). Astrocytes play a critical role in maintaining the integrity of axon function in the central nervous system and specifically in the optic nerve, and we therefore investigated the biochemical effects of L-PGDS on the proliferation of astrocytes and on the production of adenosine triphosphate (ATP) by astrocyte mitochondria. We found an inhibitory effect of L-PGDS on both proliferation of astrocytes and production of astrocyte ATP. The concentrations that inhibited astrocyte proliferation and ATP production were in the range measured in patients with idiopathic intracranial hypertension and in patients with normal-tension glaucoma. As the CSF is in contact with axons and mitochondria of the optic nerve (Bristow et al. Archives of Ophthalmology, 120, 791-796, 2002), we postulate that a change in the concentration of CSF protein such as L-PGDS could exercise a harmful effect on these structures.

Age-related increase of prostaglandin D(2) synthase concentration and glycation in ovine cerebrospinal fluid

Prostaglandin D(2) synthase (PGDS) is a glycoprotein that is exclusively brain derived and is one of the most abundant proteins in the cerebrospinal fluid (CSF). Due to its high CSF specificity, it can be used as a tool for the diagnosis of central nervous system (CNS) disorders. However, several studies have yielded contradictory CSF PGDS concentrations in various CNS neurodegenerative disorders. Sheep CSF samples from different ages were used in this study and 2-dimensional electrophoresis (2-DE) was applied in PGDS identification and concentration calculation. SYPRO Ruby Protein Gel Stain was the staining method used to stain the 2-DE gel protein spots. Pro-Q Emerald 488 Staining for Glycoproteins was used for the staining of glycoproteins. A total of nine PGDS isoforms were identified and CSF total PGDS concentration was calculated to increase linearly by 44% from young (0.9323+/-0.0637mgdL(-1)) to old (1.3669+/-0.0558mgdL(-1)). However, the proportion of CSF total PGDS as a percentage of CSF total protein was discovered to decrease exponentially with age. This was due to the influence of larger age-related increase in CSF albumin concentration (>200% from young to old) as albumin is the most abundant protein in the CSF (>60% of total CSF proteins). Active deglycosylation was not observed in PGDS isoforms during healthy ageing. Some PGDS isoforms were observed to have age-related increase in glycation. These findings suggest that CSF PGDS concentration is increased during healthy ageing and must be taken into consideration when using PGDS as a potential biomarker in diagnosing CNS neurodegenerative disorders. Whether age-related increase in the glycation of some CSF PGDS isoforms will result in detrimental effects on the PGDS protein function needs further investigations.

Proteomics analysis of perilymph and cerebrospinal fluid in mouse

OBJECTIVES

Proteins in perilymph may alter the delivery profile of implantable intracochlear drug delivery systems through biofouling. Knowledge of protein composition will help anticipate interactions with delivered agents.

STUDY DESIGN

Analysis of mouse perilymph.

METHODS

Protein composition of perilymph and cerebrospinal fluid (CSF) was analyzed using a capillary liquid chromatography-mass spectrometry-based iTRAQ quantitative proteomics approach. We searched against a mouse subset of the Uniprot FASTA protein database. We sampled perilymph from the apex of the mouse cochlea to minimize CSF contamination.

RESULTS

More than 50 explicit protein isoforms were identified with very high confidence. iTRAQ reporter ions allowed determination of relative molar amounts of proteins between perilymph and CSF. Protein in perilymph was almost three times more concentrated than in CSF. More than one-third of the proteins in perilymph comprised protease inhibitors, with serpins being the predominant group. Apolipoproteins constituted 16%. Fifteen percent of the proteins were enzymes. Albumin was the most abundant single protein (14%). Proteins with relatively high perilymph/CSF ratios included broad-spectrum protease inhibitors and apolipoproteins.

DISCUSSION

Some proteins found in perilymph, such as albumin and HMW kininogen, have been implicated in biofouling through adsorption to device materials. The relatively large quantities of apolipoprotein and albumin may serve as a reservoir for acidic and lipophilic drugs. Alpha-2-glycoprotein can bind basic drugs.

CONCLUSIONS

Perilymph is similar in protein composition to CSF, though amounts are 2.8 times higher. Protease inhibitors comprise the largest category of proteins.

Induction of lipocalin-type prostaglandin D synthase in mouse heart under hypoxemia

Hypoxemia is a common manifestation of various disorders and generates pressure overload to the heart. Here we analyzed the expression of lipocalin-type prostaglandin D synthase (L-PGDS) in the heart of C57BL/6 mice kept under normobaric hypoxia (10% O2) that generates hemodynamic stress. Northern and Western blot analyses revealed that the expression levels of L-PGDS mRNA and protein were significantly increased (> twofold) after 14 days of hypoxia, compared to the mice kept under normoxia. Immunohistochemical analysis indicated that L-PGDS was increased in the myocardium of auricles and ventricles and the pulmonary venous myocardium at 28 days of hypoxia. Moreover, using C57BL/6 mice lacking heme oxygenase-2 (HO-2(-/-)), a model of chronic hypoxemia, we showed that the expression level of L-PGDS protein was twofold higher in the heart than that of wild-type mouse. L-PGDS expression is induced in the myocardium under hypoxemia, which may reflect the adaptation to the hemodynamic stress.

Prostaglandin D(2) sustains the pyrogenic effect of prostaglandin E(2)

Prostaglandin D(2) (PGD(2)) is involved in a variety of physiological and pathophysiological processes, but its role in fever is poorly understood. Here we investigated the effects of central PGD(2) administration on body temperature and prostaglandin levels in the cerebrospinal fluid (CSF) of rats. Administration of PGD(2) into the cisterna magna (i.c.m) evoked a delayed fever response that was paralleled by increased levels of prostaglandin E(2) (PGE(2)) in the CSF. The elevated PGE(2) levels were not caused by an increased expression of cyclooxygenase 2 or microsomal prostaglandin E synthase-1 in the hypothalamus. Interestingly, i.c.m. pretreatment of animals with PGD(2) considerably sustained the pyrogenic effects of i.c.m. administered PGE(2). These data indicate that PGD(2) might control the availability of PGE(2) in the CSF and suggest that centrally produced PGD(2) may play a role in the maintenance of fever.

Lipopolysaccharide-dependent interaction between PU.1 and c-Jun determines production of lipocalin-type prostaglandin D synthase and prostaglandin D2 in macrophages

Previously, we reported that expression of lipocalin-prostaglandin D synthase (L-PGDS) is inducible in macrophages and protects from Pseudomonas pneumonia. Here, we investigated the mechanism by which L-PGDS gene expression is induced in macrophages. A promoter analysis of the murine L-PGDS promoter located a binding site of PU.1, a transcription factor essential for macrophage development and inflammatory gene expression. A chromatin immunoprecipitation assay showed that PU.1 bound to the cognate site in the endogenous L-PGDS promoter in response to LPS. Overexpression of PU.1, but not of PU.1(S148A), a mutant inert to casein kinase II (CKII) or NF-kappaB-inducing kinase (NIK), induced L-PGDS in RAW 264.7 cells. Conversely, siRNA silencing of PU.1 expression blunted productions of L-PGDS and prostaglandin D2 (PGD(2)). LPS treatment induced formation of the complex of PU.1 and cJun on the PU.1 site, but inactivation of cJun by treatment with JNK or p38 kinase inhibitor abolished the complex, and suppressed PU.1 transcriptional activity for L-PGDS gene expression. Together, these results show that PU.1, activated by CKII or NIK, cooperates with MAPK-activated cJun to maximally induce L-PGDS expression in macrophages following LPS treatment, and suggest that PU.1 participates in innate immunity through the production of L-PGDS and PGD(2).

Biochemical, functional, and pharmacological characterization of AT-56, an orally active and selective inhibitor of lipocalin-type prostaglandin D synthase

We report here that 4-dibenzo[a,d]cyclohepten-5-ylidene-1-[4-(2H-tetrazol-5-yl)-butyl]-piperidine (AT-56) is an orally active and selective inhibitor of lipocalin-type prostaglandin (PG) D synthase (L-PGDS). AT-56 inhibited human and mouse L-PGDSs in a concentration (3–250 μm)-dependent manner but did not affect the activities of hematopoietic PGD synthase (H-PGDS), cyclooxygenase-1 and -2, and microsomal PGE synthase-1. AT-56 inhibited the L-PGDS activity in a competitive manner against the substrate PGH₂ (K_m = 14 μm) with a K_i value of 75 μm but did not inhibit the binding of 13-cis-retinoic acid, a nonsubstrate lipophilic ligand, to L-PGDS. NMR titration analysis revealed that AT-56 occupied the catalytic pocket, but not the retinoid-binding pocket, of L-PGDS. AT-56 inhibited the production of PGD₂ by L-PGDS-expressing human TE-671 cells after stimulation with Ca²⁺ ionophore (5 μm A23187) with an IC₅₀ value of about 3 μm without affecting their production of PGE₂ and PGF_2α but had no effect on the PGD₂ production by H-PGDS-expressing human megakaryocytes. Orally administered AT-56 (<30 mg/kg body weight) decreased the PGD₂ production to 40% in the brain of H-PGDS-deficient mice after a stab wound injury in a dose-dependent manner without affecting the production of PGE₂ and PGF_2α and also suppressed the accumulation of eosinophils and monocytes in the bronco-alveolar lavage fluid from the antigen-induced lung inflammation model of human L-PGDS-transgenic mice.

An identification of stem cell-resembling gene expression profiles in high-grade astrocytomas

High-grade astrocytomas are among the most intractable types of cancers and are often fatal. Previous studies have suggested that high-grade astrocytomas may adopt the self-renewal and migration properties of neural stem cells (NSCs) to proliferate and spread by expressing the stem cell-specific genes. However, despite a few common molecules being documented, the molecular basis underlying these similarities remains largely unknown. To have a better understanding of the stem cell characteristics of high-grade astrocytomas, we performed the study to identify the stem cell-resembling gene expression profile in high-grade astrocytomas. cDNA microarray analysis was used to detect the differentially expressed genes of isolated human high-grade astrocytomas versus their peritumoral tissue counterparts, and the identification of stem cell-resembling genes was approached by comparing the high-grade astrocytomas-specific gene expression profile with that of NSCs identified by our previous study and other groups. We identified more than 200 high-grade astrocytomas-specific genes in this study, and near 10% genes or gene families of them exhibited similar up or down expression patterns as in NSCs. Further analysis indicated that these genes were actively involved in cell proliferation, adhesion, migration, and metastasis. This study revealed a list of stem cell-specific genes in high-grade astrocytomas, which was likely to have critical roles in determining the "stem" characteristics of high-grade astrocytomas.