Head: Julius Brtko, PhD, DSc
E-mail: julius.brtko@savba.sk

Academic Degrees:

MS, Faculty of Chemistry, Slovak Technical University, Bratislava, 1974
PhD, in Biochemistry & Chemical Sciences, Comenius University, Bratislava, 1982
DSc, in Biochemistry & Chemical Sciences, Slovak Academy of Sciences, Bratislava, 2002

Major Positions and Appointments:

1974-present,  various research positions, IEE SAS, Bratislava

1989-present   Associate Member of the European Thyroid Association
1995-present,  Science Secretary of the IEE SAS Bratislava

1995-present,  Member of the Science Committee of IEE SAS Bratislava

1995-present,  Member of the Director‘s Advisory Board of the IEE SAS, Bratislava

1997-present,  Member of International Editorial Board – Biomarkers and Environment
2000-present,  Associate Editor – Endocrine Regulations

2002-pesent,   Member of the Slovak Grant Agency Commission

2003-present,  Field Editor – General Physiology and Biophysics

2002-present,  Member of the Grant Agency Committee for Molecular and Cell Biology

2003-present,  Member of the Division Commission for Medical Pharmacology, Charles University, Czech Republic

2003-present,  Member of the Division Commission for General Medicine, Charles University, Czech Republic

2005-present,  Member of the Division Commission for Biochemistry, Comenius Univiersity, Slovak Republic

Study Stays Abroad:

1983-1984       Postdoctoral Fellow and Research Associate, University of Chicago, IL, USA;
1988                Visiting Scientist, University of Osaka, Japan
1991-present   Annually Visiting Scientist, University of Salzburg, Austria
1993                Visiting Scientist, Instituto de Investigaciones Biomédicas, CSIC, Madrid, Spain
1995                Visiting Scientist, University of Würzburg, Germany
2001                Visiting Scientist, University of Bordeaux, France

Major Research Interests:

Nuclear 3,5,3‘-triiodothyronine receptors and their role in the mechanism of thyroid hormone action. Nuclear retinoic acid receptors and their role in retinoid action. Nuclear vitamin D3 receptors and its mechanism in vitamin D action. Hormone responsive elements. Nuclear receptor corepressors and coactivators. Role of selenium in the cell; Iodothyronine deiodinases. Tissue transglutaminases. Mammary gland and breast cancer and the role of retinoic acid receptors. Thyroid cancer and the role of nuclear receptors. Prostate cancer and the role of nuclear receptors. Kojic acid and 4-pyranone derivatives as a novel source of biologically active compounds.

Honors, Awards and Prizes:

Award of the Presidium of the Slovak Academy of Sciences for invention of two mutants 5-hydroxy-2-hydroxymethyl-4 -pyranone – producing strains of Aspergillus tamarii – 1987
Award of the Slovak Endocrine Society for the „Best Paper of the Year“, 1984, 1988
European Commission Fellowship, Spain – 1993
DAAD Fellowship, Germany – 1995

Scientists: Dana Macejova, PhD, Sona Scsukova, PhD, Miroslava Jezova, PhD, Jan Liska, VMD, PhD
Postgraduate Students: Slavomira Ondkova, MS, Alzbeta Mlynarcikova, MS
Technical Assistance: Maria Danihelova, Dana Zemekova

 In the research focus of the Laboratory of Molecular Endocrinology are investigations of the characteristics and functions of nuclear receptors of hormones, so-called ligand-inducible transcription factors in the body. Fully operational nuclear receptors are indispensable not only for the biological activity of a great number of hormones but also for the efficacy of further biologically active substances. A variety of changes at the level of nuclear receptors may lead to suppression or even complete elimination of the response of the organism to the relevant hormone, which may in turn give rise to serious civilization diseases caused by partial or complete resistance of the body to the corresponding hormone.

The main scientific fields of interest: 

Ø                 Study of the mechanisms of thyroid hormone, retinoic acids, and vitamin D3  actions with special focus on their cognate nuclear receptors and corresponding coregulators aimed at elucidating the effect of endo- and exogenous factors on expression, affinity, concentration and expression of transcription factors inducible by hormones and biologically active ligands;

Ø                 Uderstanding the ability of those transcription factors to bind to specific DNA segments, so-called cis-acting responsive elements;

Ø                 Research on iodothyroine 5´-deiodinases, tissue transglutaminase and nuclear estrogen receptors;

Ø                 A further research purpose is to contribute to understanding of nuclear receptor characteristics  in normal, preneoplastic and in neoplastic tissue and to provide new information on potential modulation of nuclear receptor status in different experimental models in vitro and in vivo;

Ø                 Retinoid and rexinoid nuclear receptor subtypes diagnostics in human thyroid tumours and breast and prostate cancer tissues in order to predict success probability for the retinoic acid therapy; 

Ø                 Research is also directed on development and analysis of novel biologically active substances based on 5-hydroxy-2-hydroxymethyl)-4-pyranone with antitumour activities.

In addition, insights into mechanisms of hormone receptor interactions and of signal transduction across the membrane in relation to the physical state of the membrane are investigated.

Results of experimental in vitro and in vivo studies provided the following main contributions:

• Optimalization of the methods for exact determination of the concentration and affinity of receptors for 3.5.3´-triiodo-L-thyronine and retinoic acids and better insight into some of their physicochemical properties;
• New information concerning external influences on the status of nuclear receptors for 3,5,3´-triiodo-L-thyronine and retinoic acids in target organs of thyroid hormone;
• Better insight into the value of selenoenzyme type I iodothyronine 5´-deiodinase characteristics and the biological action of thyroid hormone in the integrated organism;
• New information on some physico-chemical properties of nuclear receptors for all-trans retinoic acid and on potential influences on their status, characteristics, and role in target organs of retinoids;
• Novel findings confirming expression of RXR beta isoform in human PBMCs;
• New information on different status of functional thyroid hormone receptors and activity of type I iodothyronine 5´-deiodinase in human thyroid toxic adenoma and cold nodules;
• New data showing different expression of a number of various nuclear receptors and their coregulators in lactating           rat mammary gland when compared to non-lactating gland;
• Novel findings on expression of a number of various nuclear receptors and their coregulators in rat mammary gland tumours;
• Synthesis and determination of antitumour activity of sulfur or selenium containing 5-hydroxy-2-(hydroxymethyl)-4-pyranone derivatives;
• New data on the effects of selected endocrine disruptors on female reproductive system.

Our original findings and the methodological potential of the Laboratory in the field of nuclear receptors presented a contribution to the cooperation with the Dept. of Chemistry and Biochemistry of the University in Salzburg, which yielded novel information on the effect of the immune response upon the status of nuclear receptors as well as on further important parameters in the spleen. Acknowledgement of the Laboratory of Molecular Endocrinology research activities is well documented by its participation in cooperation within the 5^th Framework Programme project (VITAGE) supported by  the European Commission, the Centre of Excellence Project (STRESSNUTS), supported by  the European Commission and recently, within the 6^th Framework Programme NoE project (CASCADE) (Julius Brtko, PhD, DSc) supported by the European Commission.

Slovak Grant Agency –VEGA, Project No. 2/5017/5, 2005-2007: Character, function and role of transcription factors inducible by biologically active hydrophobic molecules in rat  mammary gland
Principal Investigator: Julius Brtko, PhD, DSc

The 6^th Framework Programme of the European Commission, NoE Project No.: FOOD-CT-2004-506319 (CASCADE): Chemicals as contaminants in the food chain

Principal Investigator in Slovak Republic: Julius Brtko, PhD, DSc

Slovak Grant Agency – VEGA, Project No. 2/3052/23, 2003-2005: Xenoextrogens related disorders in female reproductive system
Principal Investigator: Sona Scsukova, PhD

Isolation of thyroid hormone receptors from cell nuclei

• Isolation of target tissue cell nuclei by isopycnic ultracentrifugation and subsequent isolation of fractions of non-histone nuclear proteins containing a set of ligand inducible transcription factors;
• Exact determination of the affinity, concentration and maximal binding capacity of nuclear receptors for all-trans retinoic acid (RAR) and of nuclear receptors for 3,5,3-triiodo-L-thyronine (TR);
• Experimental model of induction of intraductal proliferation and of carcinoma of the mammary gland in female Sprague-Dawley rats. Histological examination of tissue obtained in the experiment;
• Gel retardation radioisotope analysis (electrophoretic mobility shift assay) to investigate characteristics of complexes: RAR-RARE and TRTRE in normal, preneoplastic and neoplastic tissue;
• Super-shift assay, radioisotope method for identification of the binding of individual subtypes of nuclear receptors for all-trans retinoic acid and 3,5,3`-tiiodo-L-thyronine to corresponding specific DNA sequences, response elements
• PCR technique using reverse transcription to analyze expression of specific ligand inducible transcription factors in tissues;
• Radioisotope method for measuring activity of type I and type II iodothyronine 5`-deiodinase;
• Radioisotope method for transglutaminase activity determination;
• Determination of individual subtypes of nuclear receptors by Western-blot hybridization technique with corresponding polyclonal antibody and chemiluminiscence detection. Vertical, horizontal and two-dimensional electrophoresis in polyacrylamide gel and horizontal electrophoresis in agarose;
• Adhering cell line of rat pituitary tumor GH4C1 and non-adhering murine leukemic cell line L 1210 are routinely used in in vitro experiments;
• The method of immunizing BALB/c mice or Sprague-Dawley rats with DNA plasmid (DNA vaccination or DNA immunization) is used within international cooperation (University of Salzburg);
• The methods also include determination of selected hormones and lipids, additional cell culture techniques (ovarian granulosa cells, cumulus cells and oocytes);
• Establishment of selected hormonal receptors, their reconstitution into proteoliposomes, biophysical methods for assessing protein – lipid interactions and the physical state of membranes;
• Positron emission tomography of rat mammary gland tumours.

Analysis of retinoic receptor alpha expression by horizontal agarose electrophoresis

Macejová D., Baranová M., Líška J., Brtko J.: Expression of nuclear hormone receptors, their coregulators and type I iodothyronine 5´-deiodinase gene in mammary tissue of nonlactating and postlactating rats. Life Sci., 77: 2584-2593, 2005.

Štefánik P., Macejová D., Mravec B., Brtko J., Križanová O.: Distinct modulation of a gene expression of the type 1 and 2 IP₃ receptors by retinoic acid in brain areas. Neurochem. Int., 46: 559-564, 2005.

Brtko J., Macejová D., Knopp J., Kvetňanský R.: Stress is associated with inhibition of the type I iodothyronine 5´-deiodinase activity in rat liver. Ann. N.Y. Acad. Sci., 1018: 219-223, 2004.

Líška J., Macejová D., Galbavý Š., Baranová M., Zlatoš J., Štvrtina S., Mostböck S., Weiss R., Scheiblhofer S., Thalhamer J., Brtko J.: Treatment of 1-methyl-1-nitrosourea-induced mammary tumours with immunostimulatory CpG motifs and 13-cis retinoic acid in female rats: Histopathological study. Exp. Toxic. Pathol., 55: 173-180, 2003.

Rondahl L., Uher M., Brtko J.:  Syntheses and structure determinations of some selenocyanato- and thiocyanato-kojic acid derivatives. Heterocycl. Commun., 9: 257-258, 2003.

Brtko J., Thalhamer J.: Renaissance of the biologically active vitamin A derivatives: Established and novel directed therapies for cancer and chemoprevention (Invited review). Curr. Pharm. Design, 9: 2067-2077, 2003.

Szabová Ľ., Macejová D., Dvorčáková M., Mostböck S., Blažíčková S., Zórad Š., Walrand S., Cardinault N., Vasson M-P., Rock E., Brtko J.: Expression of nuclear retinoic acid receptor in peripheral mononuclear cells (PBMC) of healthy subjects. Life Sci., 72: 831-836, 2003.

Brtko J., Bobáľová J., Podoba J., Schmutzler C., Köhrle J.: Thyroid hormone receptors and type I iodothyronine 5´-deiodinase activity of human toxic adenomas and benign cold nodules. Exp. Clin. Endocrinol. Diabetes, 110: 166-170, 2002.

Kolena J., Scsukova S., Jezova M.: Thermal destabilization of ovarian LH/hCG receptors by negatively charged lipids. Exp. Clin. Endocrinol. Diabetes 110: 77-79, 2002

Macejova D., Dvorcakova M., Weiss R., Scheiblhoffer S., Mostbock S., Szabova L., Zorad S., Thalhammer J., Brtko J.: Reduction of 1-methyl-1-nitrosourea - induced mammary gland carcinoma by in vivo application of immunostimulatory CpG motifs in Sprague-Dawley rats. Gen. Physiol. Biophys., 20: 445-448, 2001

Macejova D., Liska J., Brtko J.: Mammary gland carcinoma-related increase of type I iodothyronine 5-deiodinase activity in Sprague-Dawley rats. Gen. Physiol. Biophys., 20: 293-302, 2001

Jezova M., Scsukova S., Nagyova E., Vranova J., Prochazka R., Kolena J.: Effect of intraovarian factors on porcine follicular cells: cumulus expansion, granulosa and cumulus cell progesterone production. Anim. Reprod. Sci., 65: 115-126, 2001

Brtko J., Hartl A., Weiss R., Bernhaupt A., Scheiblhofer S., Mostbock S., Thalhamer J.: DNA immunization in vivo down-regulates nuclear all-trans retinoic acid receptors in mouse spleen cells. Mol. Cell. Endocrinol., 165: 107-113, 2000.

Brtko J., Knopp J., Kvetňanský R.: Nuclear all-trans retinoic acid receptor status in rat liver: A comparison of effects of three different stressors: immobilization, laparotomy and 2-deoxy-D-glucose. Life Sciences, 66: 1733-1741, 2000.

Scsukova S., Jezova M., Vranova J., Kolena J.: Involvement of membrane surface charge in thermal stability of the rat ovarian LH/hCG receptor. Biochim. Biophys. Acta, 1468: 15-19, 2000

Brtko J., Mostbock S., Scheiblhofer S., Hartl A., Thalhamer J.: DNA immunization is associated with increased activity of type I iodothyronine 5‘-deiodinase in mouse liver. Mol. Cell. Endocrinol., 152: 85-89, 1999.

Schmutzler C., Brtko J., Winzer R., Jakobs T.C., Meissner-Weigl J., Simon D., Goretzki P.E., Kohrle J.: Functional retinoid and thyroid hormone receptors in human thyroid-carcinoma cell lines and tissues. Int. J. Cancer, 76: 368-376, 1998.