Istvan Szatmari

Publications of Istvan Szatmari

• Nuclear hormone receptors enable macrophages and dendritic cells to sense their lipid environment and shape their immune response.

  Authors: Laszlo Nagy, Attila Szanto, Istvan Szatmari, Lajos Széles

  Physiological reviews. 04/2012; 92(2):739-89.

  A key issue in the immune system is to generate specific cell types, often with opposing activities. The mechanisms of differentiation and subtype specification of immune cells such as macrophagesA key issue in the immune system is to generate specific cell types, often with opposing activities. The mechanisms of differentiation and subtype specification of immune cells such as macrophages and dendritic cells are critical to understand the regulatory principles and logic of the immune system. In addition to cytokines and pathogens, it is increasingly appreciated that lipid signaling also has a key role in differentiation and subtype specification. In this review we explore how intracellular lipid signaling via a set of transcription factors regulates cellular differentiation, subtype specification, and immune as well as metabolic homeostasis. We introduce macrophages and dendritic cells and then we focus on a group of transcription factors, nuclear receptors, which regulate gene expression upon receiving lipid signals. The receptors we cover are the ones with a recognized physiological function in these cell types and ones which heterodimerize with the retinoid X receptor. These are as follows: the receptor for a metabolite of vitamin A, retinoic acid: retinoic acid receptor (RAR), the vitamin D receptor (VDR), the fatty acid receptor: peroxisome proliferator-activated receptor γ (PPARγ), the oxysterol receptor liver X receptor (LXR), and their obligate heterodimeric partner, the retinoid X receptor (RXR). We discuss how they can get activated and how ligand is generated and eliminated in these cell types. We also explore how activation of a particular target gene contributes to biological functions and how the regulation of individual target genes adds up to the coordination of gene networks. It appears that RXR heterodimeric nuclear receptors provide these cells with a coordinated and interrelated network of transcriptional regulators for interpreting the lipid milieu and the metabolic changes to bring about gene expression changes leading to subtype and functional specification. We also show that these networks are implicated in various immune diseases and are amenable to therapeutic exploitation.

• Carboxypeptidase-M is regulated by lipids and CSFs in macrophages and dendritic cells and expressed selectively in tissue granulomas and foam cells.

  Authors: Ioannis Tsakiris, Daniel Torocsik, Adrienn Gyongyosi, Aniko Dozsa, Istvan Szatmari, Attila Szanto, Gyorgyike Soos, Zoltan Nemes, Laszlo Igali, Ildiko Marton, Zoltan Takats, Laszlo Nagy, Balazs Dezso

  Laboratory investigation; a journal of technical methods and pathology. 12/2011; 92(3):345-61.

  Granulomatous inflammations, characterized by the presence of activated macrophages (MAs) forming epithelioid cell (EPC) clusters, are usually easy to recognize. However, in ambiguous cases the useGranulomatous inflammations, characterized by the presence of activated macrophages (MAs) forming epithelioid cell (EPC) clusters, are usually easy to recognize. However, in ambiguous cases the use of a MA marker that expresses selectively in EPCs may be needed. Here, we report that carboxypeptidase-M (CPM), a MA-differentiation marker, is preferentially induced in EPCs of all granuloma types studied, but not in resting MAs. As CPM is not expressed constitutively in MAs, this allows utilization of CPM-immunohistochemistry in diagnostics of minute granuloma detection when dense non-granulomatous MAs are also present. Despite this rule, hardly any detectable CPM was found in advanced/active tubercle caseous disease, albeit in early tuberculosis granuloma, MAs still expressed CPM. Indeed, in vitro both the CPM-protein and -mRNA became downregulated when MAs were infected with live mycobacteria. In vitro, MA-CPM transcript is neither induced remarkably by interferon-γ, known to cause classical MA activation, nor by IL-4, an alternative MA activator. Instead, CPM is selectively expressed in lipid-laden MAs, including the foam cells of atherosclerotic plaques, xanthomatous lesions and lipid pneumonias. By using serum, rich in lipids, and low-density lipoprotein (LDL) or VLDL, CPM upregulation could be reproduced in vitro in monocyte-derived MAs both at transcriptional and protein levels, and the increase is repressed under lipid-depleted conditions. The microarray analyses support the notion that CPM induction correlates with a robust progressive increase in CPM gene expression during monocyte to MA maturation and dendritic cell (DC) differentiation mediated by granulocyte-MA-colony-stimulating factor+IL-4. M-CSF alone also induced CPM. These results collectively indicate that CPM upregulation in MAs is preferentially associated with increased lipid uptake, and exposure to CSF, features of EPCs, also. Therefore, CPM-immunohistochemistry is useful for granuloma and foam MA detections in tissue sections. Furthermore, the present data offer CPM for the first time to be a novel marker and cellular player in lipid uptake and/or metabolism of MAs by promoting foam cell formation.

• Peroxisome proliferator-activated receptor γ-regulated cathepsin D is required for lipid antigen presentation by dendritic cells.

  Authors: Britt Nakken, Tamas Varga, Istvan Szatmari, Lajos Szeles, Adrienn Gyongyosi, Petr A Illarionov, Balazs Dezso, Peter Gogolak, Eva Rajnavolgyi, Laszlo Nagy

  Journal of immunology (Baltimore, Md. : 1950). 07/2011; 187(1):240-7.

  It is well established that dendritic cells (DCs) take up, process, and present lipid Ags in complex with CD1d molecules to invariant NKT cells. The lipid-activated transcription factor, peroxisomeIt is well established that dendritic cells (DCs) take up, process, and present lipid Ags in complex with CD1d molecules to invariant NKT cells. The lipid-activated transcription factor, peroxisome proliferator-activated receptor γ (PPARγ), has previously been shown to regulate CD1d expression in human monocyte-derived DCs, providing a link between lipid metabolism and lipid Ag presentation. We report that PPARγ regulates the expression of a lysosomal protease, cathepsin D (CatD), in human monocyte-derived DCs. Inhibition of CatD specifically reduced the expansion of invariant NKT cells and furthermore resulted in decreased maturation of saposins, a group of lipid transfer proteins required for lysosomal lipid Ag processing and loading. These results reveal a novel mechanism of lipid Ag presentation and identify CatD as a key component of this machinery and firmly place PPARγ as the transcriptional regulator linking lipid metabolism and lipid Ag processing.

• Chronic obstructive pulmonary disease-specific gene expression signatures of alveolar macrophages as well as peripheral blood monocytes overlap and correlate with lung function.

  Authors: Szilard Poliska, Eszter Csanky, Attila Szanto, Istvan Szatmari, Bertalan Mesko, Lajos Szeles, Balazs Dezso, Beata Scholtz, Janos Podani, Iain Kilty, Laszlo Takacs, Laszlo Nagy

  Respiration; international review of thoracic diseases. 03/2011; 81(6):499-510.

  Chronic obstructive pulmonary disease (COPD) is a chronic inflammatory disease characterized by progressive airflow limitation and significant extrapulmonary (systemic) effects that lead to co-morbidChronic obstructive pulmonary disease (COPD) is a chronic inflammatory disease characterized by progressive airflow limitation and significant extrapulmonary (systemic) effects that lead to co-morbid conditions, though the pathomechanism of COPD is largely undetermined. Alveolar macrophages (AM) derived from peripheral monocytes (MO) appear to play a key role in initiating and/or sustaining disease progression. To identify disease- and cell type-specific gene expression profiles and potential overlaps in those in order to diagnose COPD, characterize its progression and determine the effect of drug treatment. Global gene expression analysis was used for primary screening in order to obtain expression signatures of AMs and circulating MOs of COPD patients and healthy controls. The results of microarray analyses of AMs (20 controls and 26 COPD patients) and MOs (16 controls and 22 COPD patients) were confirmed and validated by real-time quantitative polymerase chain reaction. We have identified gene sets specifically associated with COPD in AMs and MOs. There were overlapping genes between the two cell types. Our data also show that COPD-specific gene expression signatures in AMs and MOs correlate with percent of predicted FEV(1). Disease-specific and overlapping gene expression signatures can be defined in lung-derived macrophages and also in circulating monocytes. Some of the validated expression changes in both cell types correlate with lung function and therefore could serve as biomarkers of disease progression.

• Research resource: transcriptome profiling of genes regulated by RXR and its permissive and nonpermissive partners in differentiating monocyte-derived dendritic cells.

  Authors: Lajos Széles, Szilárd Póliska, Gergely Nagy, Istvan Szatmari, Attila Szanto, Attila Pap, Malin Lindstedt, Saskia J A M Santegoets, Ralph Rühl, Balázs Dezsö, László Nagy

  Molecular endocrinology (Baltimore, Md.). 11/2010; 24(11):2218-31.

  Retinoid X receptors (RXRs) are heterodimerization partners for many nuclear receptors and also act as homodimers. Heterodimers formed by RXR and a nonpermissive partner, e.g. retinoic acid receptorRetinoid X receptors (RXRs) are heterodimerization partners for many nuclear receptors and also act as homodimers. Heterodimers formed by RXR and a nonpermissive partner, e.g. retinoic acid receptor (RAR) and vitamin D receptor (VDR), can be activated only by the agonist of the partner receptor. In contrast, heterodimers that contain permissive partners, e.g. liver X receptor (LXR) and peroxisome proliferator-activated receptor (PPAR), can be activated by agonists for either the partner receptor or RXR, raising the possibility of pleiotropic RXR signaling. However, it is not known to what extent the receptor's activation results in triggering mechanisms dependent or independent of permissive heterodimers. In this study, we systematically and quantitatively characterized all probable RXR-signaling pathways in differentiating human monocyte-derived dendritic cells (Mo-DCs). Using pharmacological, microarray and quantitative RT-PCR techniques, we identified and characterized gene sets regulated by RXR agonists (LG100268 and 9-cis retinoic acid) and agonists for LXRs, PPARs, RARα, and VDR. Our results demonstrated that permissiveness was partially impaired in Mo-DCs, because a large number of genes regulated by PPAR or LXR agonists was not affected by RXR-specific agonists or was regulated to a lesser extent. As expected, we found that RXR agonists regulated only small portions of RARα or VDR targets. Importantly, we could identify and characterize PPAR- and LXR-independent pathways in Mo-DCs most likely mediated by RXR homodimers. These data suggested that RXR signaling in Mo-DCs was mediated via multiple permissive heterodimers and also by mechanism(s) independent of permissive heterodimers, and it was controlled in a cell-type and gene-specific manner.

• Nuclear receptor signalling in dendritic cells connects lipids, the genome and immune function.

  Authors: Istvan Szatmari, Laszlo Nagy

  The EMBO journal. 09/2008;

  Dendritic cells (DCs) are sentinels of the immune system and represent a heterogeneous cell population. The existence of distinct DC subsets is due to their inherent plasticity and to the changingDendritic cells (DCs) are sentinels of the immune system and represent a heterogeneous cell population. The existence of distinct DC subsets is due to their inherent plasticity and to the changing microenvironment modulating their immunological properties. Numerous signalling pathways have impacts on DCs. It appears that besides cytokines/chemokines, lipid mediators also have profound effects on the immunogenicity of DCs. Some of these lipid mediators exert an effect through nuclear hormone receptors. Interestingly, more recent findings suggest that DCs are able to convert precursors to active hormones, ligands for nuclear receptors. Some of these DC-derived lipids, in particular retinoic acid (RA), have a central function in shaping T-cell development and effector functions. In this review, we summarize and highlight the function of a set of nuclear receptors (PPARgamma, RA receptor, vitamin D receptor and glucocorticoid receptor) in DC biology. Defining the contribution of nuclear hormone receptor signalling in DCs can help one to understand the regulatory logic of lipid signalling and allow the exploitation of their potential for therapeutic intervention in various immunological diseases.

• PPARgamma regulates the function of human dendritic cells primarily by altering lipid metabolism.

  Authors: Istvan Szatmari, Daniel Töröcsik, Maura Agostini, Tibor Nagy, Mark Gurnell, Endre Barta, Krishna Chatterjee, Laszlo Nagy

  Blood. 12/2007; 110(9):3271-80.

  Activation of the lipid-regulated nuclear receptor peroxisome proliferator-activated receptor gamma (PPARgamma) modifies the immunophenotype of monocyte-derived dendritic cells (DCs). However it hasActivation of the lipid-regulated nuclear receptor peroxisome proliferator-activated receptor gamma (PPARgamma) modifies the immunophenotype of monocyte-derived dendritic cells (DCs). However it has not been analyzed in a systematic manner how lipid metabolism and immune regulation are connected at the transcriptional level via this receptor. Here we present the genome-wide expression analyses of PPARgamma-instructed human DCs. Receptor activation was achieved by exogenous, synthetic as well as endogenous, natural means. More than 1000 transcripts are regulated during DC development by activation of PPARgamma; half of the changes are positive effects. These changes appear to enhance and modulate the robust gene expression alterations associated with monocyte to DC transition. Strikingly, only genes related to lipid metabolism are overrepresented among early induced genes. As a net consequence, lipid accumulation appears to be diminished in these cells. In contrast, genes related to immune response are regulated after 24 hours, implying the existence of indirect mechanisms of modulation. Receptor dependence was established by using DCs of patients harboring a dominant-negative mutation of PPARgamma. Our data show that PPARgamma acts as a mostly positive transcriptional regulator in human developing DCs, acting primarily through controlling genes involved in lipid metabolism and via this, indirectly modifying the immune phenotype.

• Differentiation of CD1a- and CD1a+ monocyte-derived dendritic cells is biased by lipid environment and PPARgamma.

  Authors: Peter Gogolak, Bence Rethi, Istvan Szatmari, Arpad Lanyi, Balazs Dezso, Laszlo Nagy, Eva Rajnavolgyi

  Blood. 02/2007; 109(2):643-52.

  Accumulating data have shown that the microenvironment of dendritic cells modulates subtype differentiation and CD1 expression, but the mechanisms by which exogenous factors confer these effects areAccumulating data have shown that the microenvironment of dendritic cells modulates subtype differentiation and CD1 expression, but the mechanisms by which exogenous factors confer these effects are poorly understood. Here we describe the dependence of CD1a- monocyte-derived dendritic cell (moDC) development on lipids associated with the expression of peroxisome proliferator-activated receptor-gamma (PPARgamma). We also show the consecutive differentiation of immature CD1a-PPARgamma+ moDCs to CD1a+PPARgamma- cells limited by serum lipoproteins and terminated by proinflammatory cytokines. Immature CD1a- moDCs possess higher internalizing capacity than CD1a+ cells, whereas both activated subtypes have similar migratory potential but differ in their cytokine and chemokine profiles, which translates to distinct T-lymphocyte-polarizing capacities. CD1a+ moDCs stand out by their capability to secrete high amounts of IL-12p70 and CCL1. As lipoproteins skew moDC differentiation toward the generation of CD1a-PPARgamma+ cells and inhibit the development of CD1a+PPARgamma- cells, we suggest that the uptake of lipids results in endogenous PPARgamma agonists that induce a cascade of gene transcription coordinating lipid metabolism, the expression of lipid-presenting CD1 molecules, subtype dichotomy, and function. The presence of CD1a-PPARgamma+ and CD1a+PPARgamma- DCs in lymph nodes and in pulmonary Langerhans cell histiocytosis confirms the functional relevance of these DC subsets in vivo.

• PPARgamma, a lipid-activated transcription factor as a regulator of dendritic cell function.

  Authors: Istvan Szatmari, Eva Rajnavolgyi, Laszlo Nagy

  Annals of the New York Academy of Sciences. 12/2006; 1088:207-18.

  In recent years it became apparent that PPARgamma, besides being a key component of adipose tissue development and a target of insulin-sensitizing drugs, also has a role in immune cellIn recent years it became apparent that PPARgamma, besides being a key component of adipose tissue development and a target of insulin-sensitizing drugs, also has a role in immune cell differentiation and function. This receptor has been identified by us and others as a conductor of lipid handling in macrophages, and has roles also in inflammation control. Here we review recent advances on the role of this nuclear receptor in another key cell type of myeloid origin, dendritic cells (DCs). DCs are professional antigen-presenting cells having essential roles in antigen-uptake processing and presentation and in initiation of various forms of immune responses. It appears that PPARgamma is expressed and is active in myeloid DCs and likely to be a regulator of DC function by altering antigen uptake, maturation, activation, migration, cytokine production, and lipid antigen presentation. Thus PPARgamma is at the crossroads of lipid metabolism and innate immune response, and by studying its functions one has a unique opportunity to discern how these two seemingly distant fields (lipid metabolism and immune response) are interrelated. It is also possible that this receptor is a relevant target for pharmacological intervention in immune diseases such as chronic inflammation and autoimmune conditions.

• PPARgamma controls CD1d expression by turning on retinoic acid synthesis in developing human dendritic cells.

  Authors: Istvan Szatmari, Attila Pap, Ralph Rühl, Jiang-Xing Ma, Petr A Illarionov, Gurdyal S Besra, Eva Rajnavolgyi, Balazs Dezso, Laszlo Nagy

  The Journal of experimental medicine. 11/2006; 203(10):2351-62.

  Dendritic cells (DCs) expressing CD1d, a molecule responsible for lipid antigen presentation, are capable of enhancing natural killer T (iNKT) cell proliferation. The signals controlling CD1Dendritic cells (DCs) expressing CD1d, a molecule responsible for lipid antigen presentation, are capable of enhancing natural killer T (iNKT) cell proliferation. The signals controlling CD1 expression and lipid antigen presentation are poorly defined. We have shown previously that stimulation of the lipid-activated transcription factor, peroxisome proliferator-activated receptor (PPAR)gamma, indirectly regulates CD1d expression. Here we demonstrate that PPARgamma, turns on retinoic acid synthesis by inducing the expression of retinol and retinal metabolizing enzymes such as retinol dehydrogenase 10 and retinaldehyde dehydrogenase type 2 (RALDH2). PPARgamma-regulated expression of these enzymes leads to an increase in the intracellular generation of all-trans retinoic acid (ATRA) from retinol. ATRA regulates gene expression via the activation of the retinoic acid receptor (RAR)alpha in human DCs, and RARalpha acutely regulates CD1d expression. The retinoic acid-induced elevated expression of CD1d is coupled to enhanced iNKT cell activation. Furthermore, in vivo relevant lipids such as oxidized low-density lipoprotein can also elicit retinoid signaling leading to CD1d up-regulation. These data show that regulation of retinoid metabolism and signaling is part of the PPARgamma-controlled transcriptional events in DCs. The uncovered mechanisms allow the DCs to respond to altered lipid homeostasis by changing CD1 gene expression.

• Non-DNA binding, dominant-negative, human PPARgamma mutations cause lipodystrophic insulin resistance.

  Authors: Maura Agostini, Erik Schoenmakers, Catherine Mitchell, Istvan Szatmari, David Savage, Aaron Smith, Odelia Rajanayagam, Robert Semple, Jian'an Luan, Louise Bath [......] Dirk Blom, David Marais, John Schwabe, Inês Barroso, Richard Trembath, Nicholas Wareham, Laszlo Nagy, Mark Gurnell, Stephen O'Rahilly, Krishna Chatterjee

  Cell metabolism. 11/2006; 4(4):303-11.

  PPARgamma is essential for adipogenesis and metabolic homeostasis. We describe mutations in the DNA and ligand binding domains of human PPARgamma in lipodystrophic, severe insulin resistance. ThesePPARgamma is essential for adipogenesis and metabolic homeostasis. We describe mutations in the DNA and ligand binding domains of human PPARgamma in lipodystrophic, severe insulin resistance. These receptor mutants lack DNA binding and transcriptional activity but can translocate to the nucleus, interact with PPARgamma coactivators and inhibit coexpressed wild-type receptor. Expression of PPARgamma target genes is markedly attenuated in mutation-containing versus receptor haploinsufficent primary cells, indicating that such dominant-negative inhibition operates in vivo. Our observations suggest that these mutants restrict wild-type PPARgamma action via a non-DNA binding, transcriptional interference mechanism, which may involve sequestration of functionally limiting coactivators.

• Peroxisome proliferator-activated receptor gamma-regulated ABCG2 expression confers cytoprotection to human dendritic cells.

  Authors: Istvan Szatmari, György Vámosi, Peter Brazda, Balint L Balint, Szilvia Benko, Lajos Széles, Viktoria Jeney, Csilla Ozvegy-Laczka, Attila Szántó, Endre Barta, József Balla, Balazs Sarkadi, Laszlo Nagy

  The Journal of biological chemistry. 09/2006; 281(33):23812-23.

  ABCG2, a member of the ATP-binding cassette transporters has been identified as a protective pump against endogenous and exogenous toxic agents. ABCG2 was shown to be expressed at high levels in stemABCG2, a member of the ATP-binding cassette transporters has been identified as a protective pump against endogenous and exogenous toxic agents. ABCG2 was shown to be expressed at high levels in stem cells and variably regulated during cell differentiation. Here we demonstrate that functional ABCG2 is expressed in human monocyte-derived dendritic cells by the activation of a nuclear hormone receptor, PPARgamma. We identified and characterized a 150-base pair long conserved enhancer region, containing three functional PPAR response elements (PPARE), upstream of the human ABCG2 gene. We confirmed the binding of the PPARgamma x RXR heterodimer to this enhancer region, suggesting that PPARgamma directly regulates the transcription of ABCG2. Consistent with these results, elevated expression of ABCG2 mRNA was coupled to enhanced protein production, resulting in increased xenobiotic extrusion capacity via ABCG2 in PPARgamma-activated cells. Furthermore PPARgamma instructed dendritic cells showed increased Hoechst dye extrusion and resistance to mitoxantrone. Collectively, these results uncovered a mechanism by which up-regulation of functional ABCG2 expression can be achieved via exogenous or endogenous activation of the lipid-activated transcription factor, PPARgamma. The increased expression of the promiscuous ABCG2 transporter can significantly modify the xenobiotic and drug resistance of human myeloid dendritic cells.

• SLAM/SLAM interactions inhibit CD40-induced production of inflammatory cytokines in monocyte-derived dendritic cells.

  Authors: Bence Réthi, Péter Gogolák, Istvan Szatmari, Agota Veres, Erika Erdôs, Laszlo Nagy, Eva Rajnavölgyi, Cox Terhorst, Arpád Lányi

  Blood. 05/2006; 107(7):2821-9.

  Signaling lymphocyte activation molecule (SLAM, CD150, or SLAMF1) is a self-ligand receptor on the surface of activated T- and B-lymphocytes, macrophages, and dendritic cells (DCs). Here we examineSignaling lymphocyte activation molecule (SLAM, CD150, or SLAMF1) is a self-ligand receptor on the surface of activated T- and B-lymphocytes, macrophages, and dendritic cells (DCs). Here we examine the effect of SLAM/SLAM interactions on CD40L-induced CD40 signaling pathways in human DCs. CD40L-expressing L929 cells induced DCs to produce interleukin-6 (IL-6), tumor necrosis factor-alpha (TNF-alpha), and IL-12, which was strongly inhibited by coexpression of SLAM on the surface of the L929 cells. Similarly, transfection of DCs with SLAM strongly reduced CD40L-induced IL-12 production. Furthermore, the negative effect of SLAM/SLAM interactions on CD40L-induced DC activation was also detected in the presence of lipopolysaccharide (LPS). LPS-induced IL-12 secretion, however, was not inhibited by SLAM engagement. CD40L-activated DCs affected by exposure to SLAM/SLAM engagement were impaired in their ability to induce differentiation of naive T lymphocytes into interferon-gamma (IFN-gamma)-producing T-helper 1 (Th1) effector cells. These inhibitory effects were not the result of a general unresponsiveness of DCs to CD40L, as SLAM/SLAM interactions did not prevent CD40L-induced up-regulation of CD83, CD86, or human leukocyte antigen (HLA)-DQ on the surface of DCs. Taken together, the results indicate that SLAM/SLAM interactions inhibit CD40-induced signal transduction in monocyte-derived dendritic cells, an effect that was not detectable in earlier studies using anti-SLAM monoclonal antibodies.

• Inhibition of human telomerase by oligonucleotide chimeras, composed of an antisense moiety and a chemically modified homo-oligonucleotide.

  Authors: Ilona Tarkanyi, András Horváth, Istvan Szatmari, Helga Eizert, György Vámosi, Sándor Damjanovich, Evelyne Ségal-Bendirdjian, Janos Aradi

  FEBS letters. 03/2005; 579(6):1411-6.

  Most tumor cells attain their immortality by reactivating telomerase. We report here the telomerase inhibitory potential of chimeric oligonucleotides composed of a 13mer antisense sequence targetingMost tumor cells attain their immortality by reactivating telomerase. We report here the telomerase inhibitory potential of chimeric oligonucleotides composed of a 13mer antisense sequence targeting the telomerase RNA template region and a (s4dU)n moiety at its 3' or 5'-end. The increase of the thiolated chain length enhances the telomerase inhibitory potential, but decreases specificity, indicated by HIV reverse transcriptase inhibition. Chimeras with 5' (s4dU)(n)s were more potent inhibitors than the antisense alone or the 3' modified ones. Cy5-labeled (s4dU)4AS and (s4dU)8AS proved the internalization of the oligonucleotides, raising the possibility to be tested as cellular anti-telomerase agents.

• Transcriptional regulation of human CYP27 integrates retinoid, peroxisome proliferator-activated receptor, and liver X receptor signaling in macrophages.

  Authors: Attila Szanto, Szilvia Benko, Istvan Szatmari, Balint L Balint, Ibolya Furtos, Ralph Rühl, Sandor Molnar, Laszlo Csiba, Rita Garuti, Sebastiano Calandra, Hanna Larsson, Ulf Diczfalusy, Laszlo Nagy

  Molecular and cellular biology. 10/2004; 24(18):8154-66.

  Cholesterol uptake and efflux are key metabolic processes associated with macrophage physiology and atherosclerosis. Peroxisome proliferator-activated receptor gamma (PPARgamma) and liver X receptorCholesterol uptake and efflux are key metabolic processes associated with macrophage physiology and atherosclerosis. Peroxisome proliferator-activated receptor gamma (PPARgamma) and liver X receptor alpha (LXRalpha) have been linked to the regulation of these processes. It remains to be identified how activation of these receptors is connected and regulated by endogenous lipid molecules. We identified CYP27, a p450 enzyme, as a link between retinoid, PPARgamma, and LXR signaling. We show that the human CYP27 gene is under coupled regulation by retinoids and ligands of PPARs via a PPAR-retinoic acid receptor response element in its promoter. Induction of the enzyme's expression results in an increased level of 27-hydroxycholesterol and upregulation of LXR-mediated processes. Upregulated CYP27 activity also leads to LXR-independent elimination of CYP27 metabolites as an alternative means of cholesterol efflux. Moreover, human macrophage-rich atherosclerotic lesions have an increased level of retinoid-, PPARgamma-, and LXR-regulated gene expression and also enhanced CYP27 levels. Our findings suggest that nuclear receptor-regulated CYP27 expression is likely to be a key integrator of retinoic acid receptor-PPARgamma-LXR signaling, relying on natural ligands and contributing to lipid metabolism in macrophages.

• Activation of PPARgamma specifies a dendritic cell subtype capable of enhanced induction of iNKT cell expansion.

  Authors: Istvan Szatmari, Peter Gogolak, Jin Seol Im, Balazs Dezso, Eva Rajnavolgyi, Laszlo Nagy

  Immunity. 08/2004; 21(1):95-106.

  Little is known of the transcriptional events controlling the differentiation and function of dendritic cells (DC). We found that the ligand-activated transcription factor Peroxisome ProliferatorLittle is known of the transcriptional events controlling the differentiation and function of dendritic cells (DC). We found that the ligand-activated transcription factor Peroxisome Proliferator Activated Receptor gamma (PPARgamma) is immediately upregulated after the induction of monocyte-derived DC differentiation. Activation of PPARgamma changed the expression pattern of cell surface receptors and enhanced the internalizing activity of DC. Unexpectedly, we found that CD1 glycoproteins, a class of molecules responsible for the presentation of self and foreign modified lipids, were coordinately regulated by PPARgamma activation. CD1a levels were reduced, while CD1d expression was induced. Enhanced expression of CD1d was coupled to the selective induction of invariant natural-killer T cell (iNKT cell) proliferation in the presence of alpha-GalCer. These results suggest that PPARgamma orchestrates a transcriptional response leading to the development of a DC subtype with increased internalizing capacity, efficient lipid presentation, and the augmented potential to activate iNKT cells.

• Modified Telomeric Repeat Amplification Protocol: A Quantitative Radioactive Assay for Telomerase without Using Electrophoresis

  Authors: Istvan Szatmari, Szilvia Tőkés, Christopher B. Dunn, Thomas J. Bardos, Janos Aradi

  Analytical Biochemistry.

  A polymerase chain reaction (PCR)-based radioactive telomerase assay was developed in our laboratory which is quantitative and does not require electrophoretic evaluation (designated as TP-TRAP; itA polymerase chain reaction (PCR)-based radioactive telomerase assay was developed in our laboratory which is quantitative and does not require electrophoretic evaluation (designated as TP-TRAP; it utilizes two reverse primers). The main steps of the assay include (1) extension of a 20-mer oligonucleotide substrate (MTS) by telomerase, (2) amplification of the telomerase products in the presence of [3H]dTTP using the substrate oligonucleotide and two reverse primers (RPC3, 38 mer; RP, 20 mer), (3) isolation of the amplified radioactive dsDNA by precipitation and filtration, (4) determination of the radioactivity of the acid-insoluble DNA. The length of the telomerase products does not increase on amplification. This valuable feature of the assay is achieved by utilization of the two reverse primers and a highly specific PCR protocol. The assay is linear, accurate, and suitable for cell-biological studies where slight quantitative differences in telomerase activity must be detected. The assay is also suitable for screening and characterization of telomerase inhibitors, as shown with a chemically modified oligonucleotide reverse transcriptase inhibitor [(s4dU)35].