Leptin Induces Epigenetic Regulation of Transient Receptor Potential Melastatin 7 in Rat Adrenal Pheochromocytoma Cells.

Obesity elevates the plasma level of leptin, which has been associated with hypertension. Our recent studies in mice demonstrated that leptin increases blood pressure by activating the carotid sinus nerve, which transmits the chemosensory input from carotid bodies (CBs) to the medullary centers, and that the effect of leptin is mediated via Trpm7 (TRP [transient receptor potential] melastatin 7) channels in CB glomus cells. We also found that Trpm7 overexpression and Trpm7 promoter demethylation in CBs correlate positively with the hyperleptinemia and leptin receptor overexpression in CBs. Hence, we postulated that leptin epigenetically regulates Trpm7 expression in CBs. We addressed our hypothesis by using rat adrenal pheochromocytoma (PC12) cells as a model of CB glomus cells. PC12 cells expressing LEPRb (long, active form of leptin receptor) showed dramatic induction of the promoter activity and expression of Trpm7 upon leptin treatment. The increased Trpm7 expression coincided with the reduction of CpG site-specific methylation and trimethylation of H3K27 (H3 [histone 3] K27 [lysine 27]) and the increase of acetylation of H3K27 and trimethylation of H3K4 (H3 lysine 4) at the Trpm7 promoter. The inhibitor of STAT3 (signal transducer and activator of transcription 3) signaling, SD1008, reversed the leptin-induced Trpm7 promoter activity via modulations of the binding of pSTAT3 (phosphorylated STAT3) and DNMT3B (DNA methyltransferase 3B) and modifications of H3K27 and H3K4 at the Trpm7 promoter. Our results suggest that leptin-activated pSTAT3 epigenetically regulates the transcription of Trpm7 through DNA methylation and histone modifications. Because epigenetic changes are reversible, targeting epigenetic modifications of Trpm7 may serve as a new therapeutic approach for the treatment of hypertension in obesity.

Leptin Induces Hypertension Acting on Transient Receptor Potential Melastatin 7 Channel in the Carotid Body.

RATIONALE: Obesity leads to resistant hypertension and mechanisms are poorly understood, but high plasma levels of leptin have been implicated. Leptin increases blood pressure acting both centrally in the dorsomedial hypothalamus and peripherally. Sites of the peripheral hypertensive effect of leptin have not been identified. We previously reported that leptin enhanced activity of the carotid sinus nerve, which transmits chemosensory input from the carotid bodies (CBs) to the medullary centers, and this effect was abolished by nonselective blockers of Trp (transient receptor potential) channels. We searched our mouse CB transcriptome database and found that the Trpm7 (transient receptor potential melastatin 7) channel was the most abundant Trp channel. OBJECTIVE: To examine if leptin induces hypertension acting on the CB Trpm7. METHODS AND RESULTS: C57BL/6J (n=79), leptin receptor (LepRb) deficient db/db mice (n=22), and LepRb-EGFP (n=4) mice were used. CB Trpm7 and LepRb gene expression was determined and immunohistochemistry was performed; CB glomus cells were isolated and Trpm7-like current was recorded. Blood pressure was recorded continuously in (1) leptin-treated C57BL/6J mice with intact and denervated CB; (2) leptin-treated C57BL/6J mice, which also received a nonselective Trpm7 blocker FTY720 administered systemically or topically to the CB area; (3) leptin-treated C57BL/6J mice transfected with Trpm7 small hairpin RNA to the CB, and (4) Leprb deficient obese db/db mice before and after Leprb expression in CB. Leptin receptor and Trpm7 colocalized in the CB glomus cells. Leptin induced a nonselective cation current in these cells, which was inhibited by Trpm7 blockers. Leptin induced hypertension in C57BL/6J mice, which was abolished by CB denervation, Trpm 7 blockers, and Trpm7 small hairpin RNA applied to CBs. Leprb overexpression in CB of Leprb-deficient db/db mice demethylated the Trpm7 promoter, increased Trpm7 gene expression, and induced hypertension. CONCLUSIONS: We conclude that leptin induces hypertension acting on Trmp7 in CB, which opens horizons for new therapy.

Role of Isocitrate Dehydrogenase 2 on DNA Hydroxymethylation in Human Airway Smooth Muscle Cells.

Global DNA hydroxymethylation mediated by the TET (ten-eleven translocation) enzyme was induced in allergen-induced airway hyperresponsiveness in mouse lung tissues and specifically in isolated airway smooth muscle (ASM) cells. TET is an α-ketoglutarate (α-KG)-dependent enzyme, and the production of α-KG is catalyzed by IDH (isocitrate dehydrogenase). However, the role of IDH in the regulation of DNA hydroxymethylation in ASM cells is unknown. In comparison with nonasthmatic cells, asthmatic ASM cells exhibited higher TET activity and IDH2 (but not IDH-1 or IDH-3) gene expression levels. We modified the expression of IDH2 in ASM cells from humans with asthma by siRNA and examined the α-KG levels, TET activity, global DNA hydroxymethylation, cell proliferation, and expression of ASM phenotypic genes. Inhibition of IDH2 in asthmatic ASM cells decreased the α-KG levels, TET activity, and global DNA hydroxymethylation, and reversed the aberrant ASM phenotypes (including decreased cell proliferation and ASM phenotypic gene expression). Specifically, asthmatic cells transfected with siRNA against IDH2 showed decreased 5hmC (5-hydroxymethylcytosine) levels at the TGFB2 (transforming growth factor-ß2) promoter determined by oxidative bisulfite sequencing. Taken together, our findings reveal that IDH2 plays an important role in the epigenetic regulation of ASM phenotypic changes in asthmatic ASM cells, suggesting that IDH2 is a potential therapeutic target for reversing the abnormal phenotypes seen in asthma.

Benchmarking organic micropollutants in wastewater, recycled water and drinking water with in vitro bioassays.

Thousands of organic micropollutants and their transformation products occur in water. Although often present at low concentrations, individual compounds contribute to mixture effects. Cell-based bioassays that target health-relevant biological endpoints may therefore complement chemical analysis for water quality assessment. The objective of this study was to evaluate cell-based bioassays for their suitability to benchmark water quality and to assess efficacy of water treatment processes. The selected bioassays cover relevant steps in the toxicity pathways including induction of xenobiotic metabolism, specific and reactive modes of toxic action, activation of adaptive stress response pathways and system responses. Twenty laboratories applied 103 unique in vitro bioassays to a common set of 10 water samples collected in Australia, including wastewater treatment plant effluent, two types of recycled water (reverse osmosis and ozonation/activated carbon filtration), stormwater, surface water, and drinking water. Sixty-five bioassays (63%) showed positive results in at least one sample, typically in wastewater treatment plant effluent, and only five (5%) were positive in the control (ultrapure water). Each water type had a characteristic bioanalytical profile with particular groups of toxicity pathways either consistently responsive or not responsive across test systems. The most responsive health-relevant endpoints were related to xenobiotic metabolism (pregnane X and aryl hydrocarbon receptors), hormone-mediated modes of action (mainly related to the estrogen, glucocorticoid, and antiandrogen activities), reactive modes of action (genotoxicity) and adaptive stress response pathway (oxidative stress response). This study has demonstrated that selected cell-based bioassays are suitable to benchmark water quality and it is recommended to use a purpose-tailored panel of bioassays for routine monitoring.

X-ray and synchrotron diffraction studies of 2-(pyridin-2-yl)-1,10-phenanthroline in the role of ligand for two copper polymorphs or hydrogen bonded with 2,2,6,6-tetramethyl-4-oxopiperidinium hexafluorophosphate.

Different extended packing motifs of dichlorido[2-(pyridin-2-yl)-1,10-phenanthroline]copper(II), [CuCl2(C17H11N3)], are obtained, depending on the crystallization conditions. A triclinic form, (I), is obtained from dimethylformamide-diethyl ether or methanol, whereas crystallization from dimethylformamide-water yields a monoclinic form, (II). In each case, the Cu(II) centre is in a five-coordinate distorted square-pyramidal geometry. The extended packing for both forms can be described as a highly offset π-stacking arrangement, with interlayer distances of 3.674 (3) and 3.679 (3) Šfor forms (I) and (II), respectively. The reaction of diprotonated Pt(tmpip2NCN)Cl [tmpip2NCN = 2,6-bis(2,2,6,6-tetramethylpiperidylmethyl)benzyl] with AgPF6 under acidic conditions, followed by the addition of 2-(pyridin-2-yl)-1,10-phenanthroline, results in a hydrogen-bonded cocrystal, 2,2,6,6-tetramethyl-4-oxopiperidinium hexafluorophosphate-2-(pyridin-2-yl)-1,10-phenanthroline (1/1), C9H18NO(+)·PF6(-)·C17H11N3, (III). The extended packing maximizes π-π interactions in a parallel face-to-face arrangement, with an interlayer stacking distance of 3.4960 (14) Å.

Pharmacological and Genetic Blockade of Trpm7 in the Carotid Body Treats Obesity-Induced Hypertension.

[Figure: see text].

Frequent inactivation of axon guidance molecule RGMA in human colon cancer through genetic and epigenetic mechanisms.

BACKGROUND & AIMS: Repulsive guidance molecule member A (RGMA) is a glycosylphosphatidylinositol-anchored glycoprotein and axon guidance molecule that signals through its receptor, neogenin (NEO1), a homologue of the deleted-in-colorectal cancer (DCC) gene. RGMA also functions as a bone morphogenetic protein (BMP) coreceptor. We studied the potential roles of RGMA and NEO1 in colorectal cancer (CRC) pathogenesis. METHODS: We analyzed expression of RGMA and NEO1, as well as their epigenetic and genetic changes, in a large series of CRC samples, normal colon tissues, adenomas, and cell lines. These studies were accompanied by in vitro functional assay. RESULTS: RGMA and NEO1 expression were significantly down-regulated in most CRCs, adenomas, and cell lines. RGMA was frequently silenced by promoter methylation in CRCs (86.7%), adenomas (90.9%), and CRC cell lines (92.3%) but not in normal colon tissues; allelic imbalance of RGMA and NEO1 was observed in 40% and 49% of CRCs, respectively. In CRC samples, reduced RGMA levels were significantly associated with mismatch repair deficiency or mutations in KRAS or BRAF. Exposure to 5-aza-2'-deoxycytidine restored RGMA expression in CRC cell lines. Transfection of RGMA into CRC cells suppressed cell proliferation, migration, and invasion and also increased apoptosis in response to DNA-damaging agent. CONCLUSIONS: The frequent genetic and epigenetic inactivation of RGMA in CRCs and adenomas along with its in vitro function collectively support its role as a tumor suppressor in colon cells. These findings add to the expanding list of axon guidance molecules with disrupted function during colon carcinogenesis and create new opportunities for early detection and drug development.

Conjugative transfer of the Lactococcus lactis sex factor and pRS01 plasmid to Enterococcus faecalis.

The low G+C gram-positive bacterium Lactococcus lactis harbours two highly similar conjugative elements: an integrative and conjugative element called sex factor and the pRS01 plasmid. Originally, it was believed that the host range of the sex factor was limited to L. lactis subspecies. Here, it is reported that pTRK28 cointegrates of a spectinomycin-marked L. lactis sex factor and of the pRS01 conjugative plasmid can be transferred from L. lactis to Enterococcus faecalis. These results demonstrate the conjugative transfer of these elements to other bacterial species. Furthermore, it is reported that Ll.LtrB, a mobile group II intron carried by both elements, can invade its recognition site upon pRS01 conjugative transfer to E. faecalis.

Stanniocalcin-1 Reduces Tumor Size in Human Hepatocellular Carcinoma.

Growing evidence has revealed high expression levels of stanniocalcin-1 (STC1) in different types of human cancers. Numerous experimental studies using cancer cell lines demonstrated the involvement of STC1 in inflammatory and apoptotic processes; however the role of STC1 in carcinogenesis remains elusive. Hepatocellular carcinoma (HCC) an exemplified model of inflammation-related cancer, represents a paradigm of studying the association between STC1 and tumor development. Therefore, we conducted a statistical analysis on the expression levels of STC1 using clinicopathological data from 216 HCC patients. We found that STC1 was upregulated in the tumor tissues and its expression levels was positively correlated with the levels of interleukin (IL)-6 and IL-8. Intriguingly tumors with greater expression levels of STC1 (tumor/normal ≥ 2) were significantly smaller than the lower level (tumor/normal<2) samples (p = 0.008). A pharmacological approach was implemented to reveal the functional correlation between STC1 and the ILs in the HCC cell-lines. IL-6 and IL-8 treatment of Hep3B cells induced STC1 expression. Lentiviral-based STC1 overexpression in Hep3B and MHCC-97L cells however showed inhibitory action on the pro-migratory effects of IL-6 and IL-8 and reduced size of tumor spheroids. The inhibitory effect of STC1 on tumor growth was confirmed in vivo using the stable STC1-overexpressing 97L cells on a mouse xenograft model. Genetic analysis of the xenografts derived from the STC1-overexpressing 97L cells, showed upregulation of the pro-apoptotic genes interleukin-12 and NOD-like receptor family, pyrin domain-containing 3. Collectively, the anti-inflammatory and pro-apoptotic functions of STC1 were suggested to relate its inhibitory effect on the growth of HCC cells. This study supports the notion that STC1 may be a potential therapeutic target for inflammatory tumors in HCC patients.

Data for transcriptomic and iTRAQ proteomic analysis of Anguilla japonica gills in response to osmotic stress.

This article contains data related to the two research articles titled Transcriptomic and iTRAQ proteomic approaches reveal novel short-term hyperosmotic stress responsive proteins in the gill of the Japanese eel (Anguilla japonica) (Tse et al. [1]) and iTRAQ-based quantitative proteomic analysis reveals acute hypo-osmotic responsive proteins in the gills of the Japanese eel (Anguilla japonica) (Tse et al. [2]). The two research articles show the usefulness of combining transcriptomic and proteomic approaches to provide molecular insights of osmoregulation mechanism in a non-model organism, the Japanese eel. The information presented here combines the raw data from the two studies and provides an overview on the physiological functions of fish gills.

Early embryogenesis in zebrafish is affected by bisphenol A exposure.

Exposure of a developing embryo or fetus to endocrine disrupting chemicals (EDCs) has been hypothesized to increase the propensity of an individual to develop a disease or dysfunction in his/her later life. Although it is important to understand the effects of EDCs on early development in animals, sufficient information about these effects is not available thus far. This is probably because of the technical difficulties in tracing the continuous developmental changes at different stages of mammalian embryos. The zebrafish, an excellent model currently used in developmental biology, provides new insights to the field of toxicological studies. We used the standard whole-mount in situ hybridization screening protocol to determine the early developmental defects in zebrafish embryos exposed to the ubiquitous pollutant, bisphenol A (BPA). Three stages (60-75% epiboly, 8-10 somite, and prim-5) were selected for in situ screening of different molecular markers, whereas BPA exposure altered early dorsoventral (DV) patterning, segmentation, and brain development in zebrafish embryos within 24 hours of exposure.

Transcriptomic and iTRAQ proteomic approaches reveal novel short-term hyperosmotic stress responsive proteins in the gill of the Japanese eel (Anguilla japonica).

Osmoregulation is critical for the survival of fishes that migrate between freshwater (FW) and seawater (SW). The eel, as a catadromous fish, has been studied for decades to reveal the mechanisms of osmoregulation. These studies, however, have been limited by the lack of a genomic database to decipher the mechanism of osmoregulation at a molecular level. In this study, using high-throughput transcriptomic and proteomic technologies, we have provided the first genome-wide study to identify hyperosmotic responsive proteins in the gills of the Japanese eel. Deep sequencing using the 454 platform produced over 660,000 reads with a mean length of 385 bp. For the proteomic study, we collected gill samples from three different treatment groups of fish that had fully adapted to FW/SW or were transferred from FW to SW for 6h. The respective group of gill proteins were extracted and labeled using an isobaric tag for relative and absolute quantitation (iTRAQ) using LTQ-Orbitrap, a high resolution mass spectrometer. Among the 1519 proteins identified from the gill samples, 96 proteins were differentially expressed between FW and SW adapted fish. Nineteen hyperosmotic responsive proteins were detected (10 up-regulated and 9 down-regulated proteins) after 6h post FW to SW transfer. BIOLOGICAL SIGNIFICANCE: The study has provided the most comprehensive, targeted investigation of eel gill proteins to date, and shown the powerfulness of combining transcriptomic and proteomic approaches to provide molecular insights of osmoregulation mechanisms in a non-model organism, eel.

Synergistic effect of p53 on TSA-induced stanniocalcin 1 expression in human nasopharyngeal carcinoma cells, CNE2.

Human stanniocalcin 1 (STC1) has recently been identified as a putative protein factor involved in cellular apoptosis. The use of histone deacetylase inhibitor (i.e. trichostatin A (TSA)) and doxorubicin (Dox) is one of the common treatment methods to induce apoptosis in human cancer cells. A study on TSA and Dox-mediated apoptosis may shed light on the regulation and function of STC1 in cancer treatment. In this study, TSA and Dox cotreatment in human nasopharyngeal carcinoma cells (CNE2) elicited synergistic effects on STC1 gene expression and cellular apoptosis. An activation of p53 (TP53) transcriptional activity in Dox- or Dox+TSA-treated cells was revealed by the increased expression levels of p53 mRNA/protein as well as p53-driven luciferase activities. To elucidate the possible involvement of p53 in STC1 gene transcription, a vector expressing wild-type or dominant negative (DN) p53 was transiently transfected into the cells. Both STC1 promoter luciferase constructs and chromatin immunoprecipitation assays did not support the direct role of p53 in STC1 gene transactivation. However, the synergistic effects of p53 on the induction of NF-κB phosphorylation and the recruitment of acetylated histone H3 in STC1 promoter were observed in TSA-cotreated cells. The overexpression of exogenous STC1 sensitized apoptosis in Dox-treated cells. Taken together, this study provides data to show the cross talk of NF-κB, p53, and histone protein in the regulation of STC1 expression and function.

Stanniocalcin-1 regulates re-epithelialization in human keratinocytes.

Stanniocalcin-1 (STC1), a glycoprotein hormone, is believed to be involved in various biological processes such as inflammation, oxidative responses and cell migration. Riding on these emerging evidences, we hypothesized that STC1 may participate in the re-epithelialization during wound healing. Re-epithelialization is a critical step that involves keratinocyte lamellipodia (e-lam) formation, followed by cell migration. In this study, staurosporine (STS) treatment induced human keratinocyte (HaCaT) e-lam formation on fibronectin matrix and migration via the activation of focal adhesion kinase (FAK), the surge of intracellular calcium level [Ca²âº]i and the inactivation of Akt. In accompanied with these migratory features, a time- and dose-dependent increase in STC1 expression was detected. STC1 gene expression was found not the downstream target of FAK-signaling as illustrated by FAK inhibition using PF573228. The reduction of [Ca²âº]i by BAPTA/AM blocked the STS-mediated keratinocyte migration and STC1 gene expression. Alternatively the increase of [Ca²âº]i by ionomycin exerted promotional effect on STS-induced STC1 gene expression. The inhibition of Akt by SH6 and GSK3ß by lithium chloride (LiCl) could respectively induce and inhibit the STS-mediated e-lam formation, cell migration and STC1 gene expression. The STS-mediated e-lam formation and cell migration were notably hindered or induced respectively by STC1 knockdown or overexpression. This notion was further supported by the scratched wound assay. Collectively the findings provide the first evidence that STC1 promotes re-epithelialization in wound healing.

Endocrine disrupting chemicals: Multiple effects on testicular signaling and spermatogenesis.

In the past 200 years, an enormous number of synthetic chemicals with diverse structural features have been produced for industrial, medical and domestic purposes. These chemicals, originally thought to have little or no biological toxicity, are widely used in our daily lives as well as are commonly present in foods. It was not until the first World Wildlife Federation Wingspread Conference held in 1994 were concerns about the endocrine disrupting (ED) effects of these chemicals articulated. The potential hazardous effects of endocrine disrupting chemicals (EDCs) on human health and ecological well-being are one of the global concerns that affect the health and propagation of human beings. Considerable numbers of studies indicated that endocrine disruption is linked to "the developmental basis of adult disease," highlighting the significant effects of EDC exposure on a developing organism, leading to the propensity of an individual to develop a disease or dysfunction in later life. In this review, we intend to provide environmental, epidemiological and experimental data to associate pollutant exposure with reproductive disorders, in particular on the development and function of the male reproductive system. Possible effects of pollutant exposure on the processes of embryonic development, like sex determination and masculinization are described. In addition, the effects of pollutant exposure on hypothalamus-pituitary-gonadal axis, testicular signaling, steroidogenesis and spermatogenesis are also discussed.

PS-341 (bortezomib) induces lysosomal cathepsin B release and a caspase-2-dependent mitochondrial permeabilization and apoptosis in human pancreatic cancer cells.

PS-341 (bortezomib) is a potent and reversible proteosome inhibitor that functions to degrade intracellular polyubiquitinated proteins. PS-341 induces apoptosis and has shown broad antitumor activity with selectivity for transformed cells. We studied the effect of PS-341 on lysosomal and mitochondrial permeabilization, including the role of caspase-2 activation in apoptosis induction in the BxPC-3 human pancreatic carcinoma cell line. PS-341 induced a dose-dependent apoptosis in association with reactive oxygen species generation and cleavage of caspase-2 to its 33- and 14-kDa fragments. PS-341 disrupted lysosomes with redistribution of cathepsin B to the cytosol, as shown using fluorescence confocal microscopy, that was blocked by the free radical scavenger tiron but not by a caspase-2 inhibitor (benzyloxycarbonyl (Z)-VDVAD-fluoromethyl ketone (FMK)). PS-341-induced caspase-2 activation was attenuated by a selective pharmacological inhibitor of cathepsin B (R-3032), suggesting that cathepsin B release occurs upstream of caspase-2. PS-341-induced mitochondrial depolarization was attenuated by Z-VDVAD-FMK, tiron, and an inhibitor of the mitochondrial permeability transition pore (bongkrekic acid). Regulation of mitochondrial permeability by caspase-2 was confirmed using caspase-2 small interfering RNA. PS-341-induced cytochrome c release and phosphatidylserine externalization were attenuated by Z-VDVAD-FMK and partially by R-3032. PS-341 activated the BH3-only proteins Bik and Bim and down-regulated Bcl-2 and Bcl-xL mRNA and protein expression. Taken together, PS-341 induces lysosomal cathepsin B redistribution upstream of caspase-2. Caspase-2 activation regulates PS-341-induced mitochondrial depolarization and apoptosis, suggesting that caspase-2 can serve as a link between lysosomal and mitochondrial permeabilization.