Potential new genes for resistance to Mycosphaerella graminicola identified in Triticum aestivum x Lophopyrum elongatum disomic substitution lines.

Lophopyrum species carry many desirable agronomic traits, including disease resistance, which can be transferred towheat by interspecific hybridization. To identify potentially new genes for disease and insect resistance carried by individual Lophopyrum chromosomes, 19 of 21 possible wheat cultivar Chinese Spring 9 Lophopyrum elongatum disomic substitution lines were tested for resistance to barley yellow dwarf virus (BYDV), cereal yellow dwarf virus (CYDV), the Hessian fly Mayetiola destructor, and the fungal pathogens Blumeria graminis and Mycosphaerella graminicola (asexual stage: Septoria tritici). Low resistance to BYDV occurred in some of the disomic substitution lines, but viral titers were significantly higher than those of two Lophopyrum species tested. This suggested that genes on more than one Lophopyrum chromosome are required for complete resistance to this virus. A potentially new gene for resistance to CYDV was detected on wheatgrass chromosome 3E. All of the substitution lines were susceptible to Mayetiola destructor and one strain of B. graminis. Disomic substitution lines containing wheatgrass chromosomes 1E and 6E were significantly more resistant to M. graminicola compared to Chinese Spring. Although neither chromosome by itself conferred resistance as high as that in the wheatgrass parent, they do appear to contain potentially new genes for resistance against this pathogen that could be useful for future plant-improvement programs

Intracellular coexpression of CXC- and CC– chemokine receptors and their ligands in human melanoma cell lines and dynamic variations after xenotransplantation

BackgroundChemokines have been implicated in tumor progression and metastasis. In melanoma, chemokine receptors have been implicated in organ selective metastasis by regulating processes such as chemoattraction, adhesion and survival.MethodsIn this study we have analyzed, using flow cytometry, the systems formed by the chemokine receptors CXCR3, CXCR4, CXCR7, CCR7 and CCR10 and their ligands in thirteen human melanoma cell lines (five established from primary tumors and eight established from metastasis from different tissues). WM-115 and WM-266.4 melanoma cell lines (obtained from a primary and a metastatic melanoma respectively) were xenografted in nude mice and the tumors and cell lines derived from them were also analyzed.ResultsOur results show that the melanoma cell lines do not express or express in a low degree the chemokine receptors on their cell surface. However, melanoma cell lines show intracellular expression of all the aforementioned receptors and most of their respective ligands. When analyzing the xenografts and the cell lines obtained from them we found variations in the intracellular expression of chemokines and chemokine receptors that differed between the primary and metastatic cell lines. However, as well as in the original cell lines, minute or no expression of the chemokine receptors was observed at the cell surface.ConclusionsCoexpression of chemokine receptors and their ligands was found in human melanoma cell lines. However, this expression is intracellular and receptors are not found at the cell membrane nor chemokines are secreted to the cell medium. The levels of expressed chemokine receptors and their ligands show dynamic variations after xenotransplantation that differ depending on the origin of the cell line (from primary tumor or from metastasis)

Human gingival fibroblasts produce nitric oxide in response to proinflammatory cytokines

Background: Although nitric oxide (NO) synthesis is increased in periodontal disease (PD), little is known about the possible sources of production by gingival tissues. In fact, gingival tissues from patients with periodontitis demonstrate greater levels of inducible nitric oxide (iNOS) expression than healthy tissue. Macrophages are the source of the iNOS expression, with endothelial cells also contributing. In the present study, our hypothesis has been that human gingival fibroblasts (HGF) also have the ability to produce NO. We have established for the first time that HGF express increased levels of iNOS and modulate NO synthesis in response to proinflammatory cytokines that act synergistically. Methods: NO production under basal conditions or following incubation with tumor necrosis factor (TNF-α), interleukin (IL)-1ß, and inferferon (IFN)-y was assessed by measurement of stable NO metabolites, nitrite, and nitrate, in a microplate adaptation of the Griess assay. Total RNA was isolated from HGF for determination of iNOS mRNA levels. Results: We have shown that NO production is elevated in HGF that are stimulated simultaneously by TNF-α, IL-1ß, and IFN-y. Northern blot analysis confirmed that the production of iNOS mRNA by HGF is upregulated in the presence of these cytokines. Addition of mercaptoethyl guanidine (MEG), a specific inhibitor of iNOS, profoundly reduced the production of NO in HGF. Non specific inhibitors of iNOS, L-NG-monomethyl arginine (L-NMMA), and L-arginine-methyl ester (L-NAME) had little or no effect on NO produced in HGF. Conclusions: These results suggest that elevated NO production could be important in the pathogenesis of PD, and also suggest the ability of an iNOS inhibitor to modulate the disease. Treatments with drugs to block the production of nitric oxide or block its effects might be therapeutically valuable

The Actin-Sequestering Protein Thymosin Beta-4 Is a Novel Target of Hypoxia-Inducible Nitric Oxide and HIF-1α Regulation

The actin-sequestering protein thymosin beta-4 (Tβ4) is involved in various cellular and physiological processes such as proliferation, motility, growth and metastasis. Nitric oxide (NO) promotes tumor invasiveness and metastasis by activating various enzymes. Herein, we investigated whether hypoxia-inducible NO regulates Tβ4 expression and cancer cell migration using HeLa cervical cancer cells. NO production and Tβ4 expression were increased in a hypoxic condition. The treatment with N-(β-D-Glucopyranosyl)-N2-acetyl-S-nitroso-D, L-penicillaminamide (SNAP-1), to generate NO, enhanced the transcription of Tβ4 and cancer cell migration. SNAP-1-induced cell migration was decreased by the inhibition of Tβ4 with small interference (si) RNA. In a hypoxic condition, treatment with N(G)-monomethyl-L-arginine (L-NMMA), nitric oxide synthase (NOS) inhibitor, reduced Tβ4 transcriptional activity, and hypoxia-inducible factor (HIF)-1α. Hypoxia-induced cancer cell migration was also decreased by L-NMMA treatment. In a normoxic condition, Tβ4 transcriptional activity was decreased in the cells incubated in the presence of L-NMMA after co-transfection with Tβ4 promoter and GST-conjugated HIF-1α. Collectively, these results suggest that NO could regulate the expression of Tβ4 by direct or indirect effect of HIF-1α on Tβ4 promoter