Association of MAOA and COMT gene polymorphisms with palatable food intake in children

Several studies have implicated dopamine (DA) in appetite regulation. The enzymes catechol-o-methyltransferase (COMT) and monoamine oxidase A (MAOA) control DA availability and their genes have well-characterized functional variants. In this study, we examined three polymorphisms in these genes, T941G and MAOAu-VNTR in the MAOA gene and Val158Met in the COMT gene, to investigate how heritable variations in enzymes that determine DA levels might influence food intake and nutritional status. This investigation was a cross-sectional examination of 354 Brazilian children of three to four years old. Polymorphisms were analyzed by PCR-based methods. Means of dietary and anthropometric data were compared among genotypes by one-way analyses of variance or Kruskal Wallis tests. The MAOAu-VNTR and COMT Val158Met polymorphisms were associated with the amount of palatable food intake in boys. Presence of the MAOAu-VNTR*long allele was associated with higher intake of lipid-dense foods (LDF) when compared with the *short allele (P=.009); the amount of sugar-dense foods (SDF) intake was also higher in males carriers of the MAOAu-VNTR *long allele than in carriers of the *short allele (P=.034). In the girls' sample, MAOAu-VNTR polymorphism was not associated with food intake and nutritional status. Carriers of the COMT Val158Met*Val allele presented higher intake of LDF when compared with Met/Met homozygotes (P=.008). This study provides the first indication that genetic variants of enzymes that control DA availability might be involved in determination of the amount of palatable food intake in children.     

Effect of cyclooxygenase genotype and dietary fish oil on colonic eicosanoids in mice

Dietary ω3 fatty acids can modulate substrate availability for cyclooxygenases (COXs) and lipoxygenases, thus modulating downstream eicosanoid formation. This could be an alternative approach to using nonsteroidal anti-inflammatory drugs and other COX inhibitors for limiting Prostaglandin E(2) (PGE(2)) synthesis in colon cancer prevention. The aims of this study were to evaluate to what extent COX- and lipoxygenase-derived products could be modulated by dietary fish oil in normal colonic mucosa and to evaluate the role of COX-1 and COX-2 in the formation of these products. Mice (wild-type, COX-1 null or COX-2 null) were fed a diet supplying a broad mixture of fatty acids present in European/American diets, supplemented with either olive oil (oleate control diet) or menhaden (fish) oil ad libitum for 9-11 weeks. Colonic eicosanoid levels were measured by liquid chromatography tandem mass spectroscopy (LC-MS/MS), and proliferation was assessed by Ki67 immunohistochemistry. For the dietary alteration of colonic arachidonic acid: eicosapentaenoic ratios resulted in large shifts in formation of COX and lipoxygenase metabolites. COX-1 knockout virtually abolished PGE(2) formation, but interestingly, 12-hydroxyeicosatetraenoic (12-HETE) acid and 15-HETE formation was increased. The large changes in eicosanoid profiles were accompanied by relatively small changes in colonic crypt proliferation, but such changes in eicosanoid formation might have greater biological impact upon carcinogen challenge. These results indicate that in normal colon, inhibition of COX-2 would have little effect on reducing PGE(2) levels.     

Effect of stationary magnetic field strengths of 150 and 200 mT on reactive oxygen species production in soybean

Our previous investigation reported the beneficial effect of pre-sowing magnetic treatment for improving germination parameters and biomass accumulation in soybean. In this study, soybean seeds treated with static magnetic fields of 150 and 200 mT for 1 h were evaluated for reactive oxygen species (ROS) and activity of antioxidant enzymes. Superoxide and hydroxyl radicals were measured in embryos and hypocotyls of germinating seeds by electron paramagnetic resonance spectroscopy and kinetics of superoxide production; hydrogen peroxide and antioxidant activities were estimated spectrophotometrically. Magnetic field treatment resulted in enhanced production of ROS mediated by cell wall peroxidase while ascorbic acid content, superoxide dismutase and ascorbate peroxidase activity decreased in the hypocotyl of germinating seeds. An increase in the cytosolic peroxidase activity indicated that this antioxidant enzyme had a vital role in scavenging the increased H(2)O(2) produced in seedlings from the magnetically treated seeds. Hence, these studies contribute to our first report on the biochemical basis of enhanced germination and seedling growth in magnetically treated seeds of soybean in relation to increased production of ROS.     

Expression of a synthetic cry1AcF gene in transgenic Pigeon pea confers resistance to Helicoverpa armigera

Pigeon pea is an important legume. Yield losses due to insect pests are enormous in the cultivation of this crop. Expression of cry proteins has led to increased resistance to pests in several crops. We report in this paper, expression of a chimeric cry1AcF (encoding cry1Ac and cry1F domains) gene in transgenic pigeon pea and its resistance towards Helicoverpa armigera. PCR, Southern hybridization, RT‐PCR and Western analysis confirmed stable integration and expression of the cry1AcF gene in pigeon pea transgenics. When screened for efficacy of the transformants for resistance against H. armigera, the transgenics showed not only high mortality of the larva but could also resist the damage caused by the larvae. Analysis for the stable integration, expression and efficacy of the transgenics resulted in the identification of four T3 plants arising from two T1 backgrounds as highly promising. The results demonstrate potentiality of the chimeric cry1AcF gene in developing H. armigera‐resistant pigeon pea.     

A PACS-1, GGA3 and CK2 complex regulates CI-MPR trafficking

The cation-independent mannose-6-phosphate receptor (CI-MPR) follows a highly regulated sorting itinerary to deliver hydrolases from the trans-Golgi network (TGN) to lysosomes. Cycling of CI-MPR between the TGN and early endosomes is mediated by GGA3, which directs TGN export, and PACS-1, which directs endosome-to-TGN retrieval. Despite executing opposing sorting steps, GGA3 and PACS-1 bind to an overlapping CI-MPR trafficking motif and their sorting activity is controlled by the CK2 phosphorylation of their respective autoregulatory domains. However, how CK2 coordinates these opposing roles is unknown. We report a CK2-activated phosphorylation cascade controlling PACS-1- and GGA3-mediated CI-MPR sorting. PACS-1 links GGA3 to CK2, forming a multimeric complex required for CI-MPR sorting. PACS-1-bound CK2 stimulates GGA3 phosphorylation, releasing GGA3 from CI-MPR and early endosomes. Bound CK2 also phosphorylates PACS-1Ser(278), promoting binding of PACS-1 to CI-MPR to retrieve the receptor to the TGN. Our results identify a CK2-controlled cascade regulating hydrolase trafficking and sorting of itinerant proteins in the TGN/endosomal system.     

Chromium activates glucose transporter 4 trafficking and enhances insulin-stimulated glucose transport in 3T3-L1 adipocytes via a cholesterol-dependent mechanism

Evidence suggests that chromium supplementation may alleviate symptoms associated with diabetes, such as high blood glucose and lipid abnormalities, yet a molecular mechanism remains unclear. Here, we report that trivalent chromium in the chloride (CrCl3) or picolinate (CrPic) salt forms mobilize the glucose transporter, GLUT4, to the plasma membrane in 3T3-L1 adipocytes. Concomitant with an increase in GLUT4 at the plasma membrane, insulin-stimulated glucose transport was enhanced by chromium treatment. In contrast, the chromium-mobilized pool of transporters was not active in the absence of insulin. Microscopic analysis of an exofacially Myc-tagged enhanced green fluorescent protein-GLUT4 construct revealed that the chromium-induced accumulation of GLUT4-containing vesicles occurred adjacent to the inner cell surface membrane. With insulin these transporters physically incorporated into the plasma membrane. Regulation of GLUT4 translocation by chromium did not involve known insulin signaling proteins such as the insulin receptor, insulin receptor substrate-1, phosphatidylinositol 3-kinase, and Akt. Consistent with a reported effect of chromium on increasing membrane fluidity, we found that chromium treatment decreased plasma membrane cholesterol. Interestingly, cholesterol add-back to the plasma membrane prevented the beneficial effect of chromium on both GLUT4 mobilization and insulin-stimulated glucose transport. Furthermore, chromium action was absent in methyl-beta-cyclodextrin-pretreated cells already displaying reduced plasma membrane cholesterol and increased GLUT4 translocation. Together, these data reveal a novel mechanism by which chromium may enhance GLUT4 trafficking and insulin-stimulated glucose transport. Moreover, these findings at the level of the cell are consistent with in vivo observations of improved glucose tolerance and decreased circulating cholesterol levels after chromium supplementation.     

West Nile Virus Capsid Degradation of Claudin Proteins Disrupts Epithelial Barrier Function

During acute infection, West Nile virus (WNV) has been reported to infect a variety of cell types in various tissues of both experimentally and naturally infected hosts. Virus infects epithelial cells in the skin, kidney, intestine, and testes, although the importance of these findings is unclear. In the current study, we have observed that WNV infection of kidney tubules in mice coincides with the loss of expression of several members of the claudin family. Proteins of this family are often involved in epithelial barrier formation and function. WNV infection of epithelial cells in culture resulted in a decrease in the transepithelial electrical resistance, an increase in the efflux of mannitol across the monolayer, and a loss of intracellular levels of claudin-1 to -4. WNV capsid alone was sufficient for the degradation event, which was mediated through lysosomal proteases. Since epithelial cells are frequent sites of WNV infection, these observations imply a potential mechanism for virus dissemination and extraneural pathogenesis.West Nile Virus (WNV) is a mosquito-borne flavivirus that first appeared in the United States in 1999. Since that time, the virus has spread across the continental United States, causing significant morbidity and mortality. Roughly 20% of WNV infections are symptomatic, and approximately 1 out of every 150 infections progresses to encephalitis and/or meningitis (39, 42). Following the bite of a carrier mosquito, WNV infection of the host is thought to initiate in the Langerhans cells of the skin (13). Viral replication continues in the regional tissue and lymph nodes, which results in the dissemination of the virus into the bloodstream. Replication then proceeds at several sites throughout the host, including the kidneys, heart, connective tissue, smooth muscle, spleen, and ultimately the brain (46). Infection of the nervous system is characteristic of the most severe cases of WNV disease, often resulting in death or long-term neurologic sequelae (26). Pathologies associated with extraneural sites of infection have also been reported, including acute renal failure (11, 24).Epithelial cells are major targets of WNV infection in vivo in both humans and experimentally infected rodents. In a hamster model of WNV infection, virus can be detected in the epithelial cells of the kidney up to 60 days postinfection, suggesting that this tissue may be a site of viral persistence (53). Infection of kidney epithelium has also been found in WNV-infected mice (20) and dogs (12). In WNV-infected humans, epithelial cell infection has also been demonstrated in several organs, including the kidney, lung, pancreas, thyroid, intestine, and testes (4). These studies suggest that the epithelial cells may play an important role in WNV pathogenesis. However, the growth characteristics of WNV in epithelial cells and the effect of WNV on the polarity and permeability functions of polarized epithelial cells have not been investigated. One important feature of epithelial cells is the presence of tight junctions (TJ). TJ are intercellular contacts between endothelial or epithelial cells which allow the formation of polarized cells with discrete apical and basolateral plasma membrane domains and separate physiologically distinct apical and basolateral fluid compartments (22). Macromolecules larger than 30 Å in diameter are generally excluded from the TJ, but permeability to small ions varies depending on tissue-specific requirements and local physiological stimuli (2, 23). TJ are thus not static seals but dynamic structures subject to transient changes in permeability (30). The TJ is composed of the transmembrane proteins occludin, claudin (a family of more than 20 members), and junctional adhesion molecule (a family of four known members). These proteins mediate cell-cell interactions and regulate junctional permeability. The transmembrane proteins interact on their cytoplasmic side with several other components of the TJ. These include zonula occludens 1, 2, and 3 (ZO-1 to -3, which belong to a family of membrane-associated guanylate kinase homologues). ZO-1 is thought to nucleate the initial formation of the TJ and to provide a scaffold for TJ assembly. This process is thought to require the interaction of ZO-1 with the adherens junction (1, 7).In this study, we show that WNV infection of epithelial cells in vivo and in vitro results in a loss of claudin protein expression. The loss of claudin expression coincides with perturbation of the permeability functions of cultured epithelial cells as measured by a reduction in transepithelial electrical resistance (TER) and an increase in the efflux of [¹⁴C]mannitol across the cell monolayer. Expression of WNV capsid alone was sufficient to mediate these events. Epithelial cells are likely to be targets for WNV infection from the earliest times of exposure (e.g., the keratinocytes at the site of the mosquito bite) and also may be sites of long-term persistence. Therefore, the effect of the virus on the TJ, a crucial component of epithelial function, suggests a possible mechanism of virus spread, as well as potentially contributing to pathogenesis.