Dénes Nagy

Publications (3)6.85 Total impact

• Article: Inhibition of TASK-3 (KCNK9) channel biosynthesis changes cell morphology and decreases both DNA content and mitochondrial function of melanoma cells maintained in cell culture.

  Lívia Kosztka, Zoltán Rusznák, Dénes Nagy, Zsuzsanna Nagy, János Fodor, Géza Szucs, Andrea Telek, Mónika Gönczi, Olga Ruzsnavszky, Norbert Szentandrássy, László Csernoch
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  ABSTRACT: TASK-3 channel overexpression was shown to facilitate the survival of malignantly transformed cells, possibly by providing greater hypoxia tolerance through a still unknown mechanism. Although it has been suggested previously that TASK-3 channels are expressed in the mitochondrial membranes, their role here remains elusive. In this study, a transient transfection of TASK-3 knockdown melanoma cell cultures was produced to show the significance of TASK-3 expression. Reduction of the TASK-3 protein biosynthesis induced characteristic changes in cell morphology, reduced the amount of DNA and decreased metabolic activity and mitochondrial function of melanoma cells when compared with control. These findings indicate that TASK-3 channel expression and function is indispensable for the proliferation and/or survival of the melanoma cells, as they seem to contribute to their mitochondrial functions. The significance is that, in this study, we have shown that TASK-3 channels are expressed in the mitochondria of melanoma malignum cells, and they are essential for maintaining cellular integrity and viability. The TASK-3 knockdown melanoma cell line had altered morphology, reduced DNA content, decreased metabolic activity and impaired mitochondrial function. These data indicate that TASK-3 channels are functionally present in the mitochondria of the melanoma cells, and their function is essential for the survival of these cells, thus TASK-3 channels may be the possible targets of future anticancer therapy.
  Melanoma research 04/2011; 21(4):308-22. · 2.06 Impact Factor
• Article: Cytoplasmic Ca2+ concentration changes evoked by muscarinic cholinergic stimulation in primary and metastatic melanoma cell lines.

  Dénes Nagy, Lívia Kosztka, Pál Pap, Zsuzsanna Nagy, Zoltán Rusznák, László Csernoch, Géza Szücs
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  ABSTRACT: Experiments were performed to explore differences between cultured primary and metastatic melanoma cell lines in their muscarinic acetylcholine receptor-mediated intracellular Ca signalization. The expression of type 1 and type 3 muscarinic receptors was detected and compared at the protein level using both immunocytochemistry and semiquantitative western blotting. The functionality of muscarinic receptors was tested by applying carbamylcholine (CCh; 1 mmol/l) and by recording the associated increases in cytoplasmic Ca using Ca imaging with the application of the Ca indicator dye, fluo-4. These data indicate that the expression levels of the receptor proteins were not significantly different in the metastatic (HT199, HT168-M1) and the primary (WM35) cell lines. Although Ca transients were evoked in all the three cell lines by CCh, the proportion of the CCh-positive cells was smaller amongst the WM35 cells. The Ca transients could be effectively blocked by atropine (0.1 mmol/l). The time courses of the Ca transients were highly variable, and in some instances they showed a late (plateau-like) component whose presence crucially depended on the influx of extracellular Ca. When the extracellular Ca concentration was reduced, the duration of the CCh-evoked transients was considerably decreased; a phenomenon that was more pronounced in the metastatic cell lines. Although there are no fundamental differences in the muscarinic receptor-mediated Ca signalization of the primary and metastatic cell lines, the quantitative differences showed in this study may partially explain the increased malignancy and migratory potential of the metastatic cells.
  Melanoma research 11/2010; · 2.06 Impact Factor
• Article: Voltage-gated potassium channel (Kv) subunits expressed in the rat cochlear nucleus.

  Zoltán Rusznák, Gábor Bakondi, Krisztina Pocsai, Agnes Pór, Lívia Kosztka, Balázs Pál, Dénes Nagy, Géza Szucs
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  ABSTRACT: Because the neuronal membrane properties and firing characteristics are crucially affected by the depolarization-activated K(+) channel (Kv) subunits, data about the Kv distribution may provide useful information regarding the functionality of the neurons situated in the cochlear nucleus (CN). Using immunohistochemistry in free-floating slices, the distribution of seven Kv subunits was described in the rat CN. Positive labeling was observed for Kv1.1, 1.2, 1.6, 3.1, 3.4, 4.2, and 4.3 subunits. Giant and octopus neurons showed particularly strong immunopositivity for Kv3.1; octopus neurons showed intense Kv1.1- and 1.2-specific reactions also. In the latter case, an age-dependent change of the expression pattern was also documented; although both young and older animals produced definite labeling for Kv1.2, the intensity of the reaction increased in older animals and was accompanied with the translocation of the Kv1.2 subunits to the cell surface membrane. The granule cell layer exhibited strong Kv4.2-specific immunopositivity, and markedly Kv4.2-positive glomerular synapses were also seen. It was found that neither giant nor pyramidal cells were uniform in terms of their Kv expression patterns. Our data provide new information about the Kv expression of the CN and also suggest potential functional heterogeneity of the giant and pyramidal cells.
  Journal of Histochemistry and Cytochemistry 06/2008; 56(5):443-65. · 2.72 Impact Factor