MTM1 displays a new function in the regulation of nickel resistance in Saccharomyces cerevisiae.

Nickel (Ni) is an essential yet toxic trace element. Although a cofactor for many metalloenzymes, nickel function and metabolism is not fully explored in eukaryotes. Molecular biology and metallomic methods were utilized to explore the new physiological functions of nickel in Saccharomyces cerevisiae. Here we showed that MTM1 knockout cells displayed much stronger nickel tolerance than wild-type cells and mitochondrial accumulations of Ni and Fe of mtm1Δ cells dramatically decreased compared to wild-type cells when exposed to excess nickel. Superoxide dismutase 2 (Sod2p) activity in mtm1Δ cells was severely attenuated and restored through Ni supplementation in media or total protein. SOD2 mRNA level of mtm1Δ cells was significantly higher than that in the wild-type strain but was decreased by Ni supplementation. MTM1 knockout afforded resistance to excess nickel mediated through reactive oxygen species levels. Meanwhile, additional Ni showed no significant effect on the localization of Mtm1p. Our study reveals the MTM1 gene plays an important role in nickel homeostasis and identifies a novel function of nickel in promoting Sod2p activity in yeast cells.

A novel functional role of nickel in sperm motility and eukaryotic cell growth.

BACKGROUND: Metal ions are essential for numerous life processes. This study aims to investigate the relationship between seminal quality and ion levels in seminal plasma. BASIC PROCEDURES: A total of 205 semen samples were collected and seminal plasma ion levels were examined with inductively-coupled plasma-mass spectrometry. The nickel function was demonstrated by in vitro assay and cell growth. MAIN FINDINGS: The low sperm motility group showed distinctively reduced nickel concentration in seminal plasma compared with the normal sperm motility group. However, arsenic, sulfur, selenium, magnesium and zinc were negatively associated with sperm quality. No significant relationship between other examined cations and semen quality was observed. In vitro assay suggested low concentration of nickel significantly increased sperm total motility and progressive motility. Cell growth assay further confirmed nickel promoted eukaryotic yeast cell growth. Nickel level in seminal plasma may play important functions to determine sperm quality. PRINCIPAL CONCLUSIONS: Our study reveals a strong correlation between S, Mg, Se, Zn, As, Ni and seminal quality as well as discovers a novel functional role of nickel in sperm motility and eukaryotic cell growth. These findings may provide a potential avenue for assessment of sperm quality and treatment of reproduction disorders.

Expression of iron homeostasis proteins in the spinal cord in experimental autoimmune encephalomyelitis and their implications for iron accumulation.

Iron accumulation occurs in the CNS in multiple sclerosis (MS) and in experimental autoimmune encephalomyelitis (EAE). However, the mechanisms underlying such iron accumulation are not fully understood. We studied the expression and cellular localization of molecules involved in cellular iron influx, storage, and efflux. This was assessed in two mouse models of EAE: relapsing-remitting (RR-EAE) and chronic (CH-EAE). The expression of molecules involved in iron homeostasis was assessed at the onset, peak, remission/progressive and late stages of the disease. We provide several lines of evidence for iron accumulation in the EAE spinal cord which increases with disease progression and duration, is worse in CH-EAE, and is localized in macrophages and microglia. We also provide evidence that there is a disruption of the iron efflux mechanism in macrophages/microglia that underlie the iron accumulation seen in these cells. Macrophages/microglia also lack expression of the ferroxidases (ceruloplasmin and hephaestin) which have antioxidant effects. In contrast, astrocytes which do not accumulate iron, show robust expression of several iron influx and efflux proteins and the ferroxidase ceruloplasmin which detoxifies ferrous iron. Astrocytes therefore are capable of efficiently recycling iron from sites of EAE lesions likely into the circulation. We also provide evidence of marked dysregulation of mitochondrial function and energy metabolism genes, as well as of NADPH oxidase genes in the EAE spinal cord. This data provides the basis for the selective iron accumulation in macrophage/microglia and further evidence of severe mitochondrial dysfunction in EAE. It may provide insights into processes underling iron accumulation in MS and other neurodegenerative diseases in which iron accumulation occurs.

Copper-zinc superoxide dismutase-deficient mice show increased susceptibility to experimental autoimmune encephalomyelitis induced with myelin oligodendrocyte glycoprotein 35-55.

In this report, we have addressed the role of copper-zinc superoxide dismutase (SOD1) deficiency in the mediation of central nervous system autoimmunity. We demonstrate that SOD1-deficient C57Bl/6 mice develop more severe autoimmune encephalomyelitis induced with myelin oligodendrocyte glycoprotein (MOG) 35-55, compared with wild type mice. This alteration in the disease phenotype was not due to aberrant expansion of MOG-specific T cells nor their ability to produce inflammatory cytokines; rather lymphocytes generated in SOD1-deficient mice were more prone to spontaneous cell death when compared with their wild type littermate controls. The data point to a role for SOD1 in the maintenance of self-tolerance leading to the suppression of autoimmune responses.

Biotransformation of Korean Panax ginseng by Pectinex.

Ginsenosides comprise the major component of ginseng exhibit various types of biological activity, including antiinflammatory and antitumor effects. In these pharmacological actions, it is thought that these activities are carried out by the metabolites of ginsenosides metabolized by human intestinal microflora. It has also been reported that their clinical efficacy varies with the hydrolyzing potential of the components of the intestinal microflora. We tried to develop a process for metabolizing ginsenosides to compound K using food-grade enzymes, which can be used commercially. Among these, Pectinex proved to be the most effective mediator of the catabolism of ginsenosides to compound K. The optimal conditions for this biotransformation were determined to be as follows: 10 to 15% rootlet ginseng, pH 5, 50 degrees C, and 2 to 3 d of incubation, to yield 20.0 mg of compound K/g of rootlet ginseng. We suggest that the metabolism of ginseng to compound K in the presence of Pectinex has many advantages over previous methods, in respects of use of raw, non-extracted rootlet ginseng, which do not require more organic solvents and evaporation apparatus. Potential metabolites PG1, PG2, PG3, and PG4 were detected in Pectinex-treated rootlet ginseng using by TLC and HPLC and, among them, PG4 was identified as compound K by TLC, HPLC, and MS. Additional studies will be carried out to determine the structure of these metabolites of ginseng and to understand the relationship between their structures and activities.

Differences in signaling pathways by IL-1beta and IL-18.

IL-1 and IL-18 are members of the IL-1 family of ligands, and their receptors are members of the IL-1 receptor family. Although several biological properties overlap for these cytokines, differences exist. IL-18 uniquely induces IFN-gamma from T lymphocytes and natural killer cells but does not cause fever, whereas fever is a prominent characteristic of IL-1 in humans and animals. In the present study, human epithelial cells were stably transfected with the IL-18 receptor beta chain and responded to IL-18 with increased production of IL-1alpha, IL-6, and IL-8. Five minutes after exposure to either cytokine, phosphorylation of mitogen activated protein kinase (MAPK) p38 was present; specific inhibition of p38 MAPK reduced IL-18 activity to background levels. Whereas IL-1beta induced the expression of the NF-kappaB-reporter gene and was suppressed by competitive inhibition of NF-kappaB binding, IL-18 responses were weak or absent. In contrast to IL-1beta, IL-18 also did not activate degradation of the NF-kappaB inhibitor. After 4 h, both cytokines induced comparable levels of mRNA for the chemokine IL-8 but, in the same cells, steady-state levels of cyclooxygenase (COX)-2 mRNA were high after IL-1beta but low or absent after IL-18. After 30 h, IL-18-induced COX-2 appeared in part to be IL-1 dependent. Similarly, low levels of prostaglandin E2 were measured in IL-18-stimulated A549 cells and freshly obtained primary human monocytes and mouse macrophages. We conclude that in epithelial cells, IL-18 signal transduction is primarily via the MAPK p38 pathway rather than NF-kappaB, which may explain the absence of COX-2 and the failure of IL-18 to cause fever.