senior research associate
senior research associate
|Margit PÁL||research associate|
|Ágota NAGY||Ph.D. student|
LABORATORY OF CELL CYCLE AND TRANSCRIPTION REGULATION AND LENDÜLET LABORATORY OF CELL CYCLE REGULATION
PROJECT 1. The role of protein phosphatases in cell cycle regulation
(supervisor: Zoltan Lipinszki)
The misregulation of cell division during the animal cell cycle results in serious developmental defects or cell proliferative diseases, such as cancer. Fundamental to screening for or correcting the resultant abnormalities in humans is defining their underlying molecular etiology. It is well established that kinase-mediate protein phosphorylation can serve as a molecular switch to fine-tune the activities of different molecular complexes during cell division. Key to the success of this regulatory mechanism is its reversibility; an antagonistic enzymatic activity driven by protein phosphatases. Despite this recognition, relatively little is known about how protein phosphatases govern cell division.
Our group is interested in the characterization and functional analysis of PP2A-like Ser/Thr phosphoprotein phosphatases. PP2A phosphatases are comprised of one evolutionarily conserved catalytic subunit, a structural subunit and a variable number of regulatory 3 subunits, or R3s. The R3 subunit is responsible for the subcellular localization of the holoenzyme as well as the selective binding to interacting partners or particular substrates of the phosphatase. Towards defining the complex interplay and regulation of PP2A-like phosphatases we utilise the Drosophila melanogaster model system. The fruit fly recapitulates the phosphatase system observed in humans but with the ability to integrate biochemical, cell biological, proteomic and genetic experimental approaches.
PROJECT 2. The role of the ubiquitin-proteasome system and the APC/C in cell cycle regulation
(supervisor: Peter Deak)
Orderly and timely progression through the cell division cycle is essential to maintain genome stability in eukaryotes. Errors in this process alter gene dosage and can result in developmental defects or cancer. Key transitions in the eukaryotic cell cycle are regulated through intracellular proteolysis by the ubiquitin-proteasome system (UPS). Due to the irreversible nature of protein degradation, by sequentially removing regulators, this process generates directionality in the cell cycle and ensures proper timing and coordination of events. Degradation of proteins by the ubiquitin-mediated protein degradation involves two successive steps: tagging of substrate proteins by the covalent attachment of polyubiquitin chains and the subsequent degradation of the tagged protein by the 26S proteasome. Besides the ubiquitin conjugating pathway and the 26S proteasome, additional factors like deubiquitylating enzymes (DUBs) and polyubiquitin binding proteins (UBPs) are involved in the efficient degradation of target proteins.
A typical eye phenotype observed upon the depletion of DmUsp5 protein as a consequence of an irregularly induced apoptosis.
Our group studies the unique contribution of the APC/C (anaphase promoting complex) and proteasome subunits, the DUB enzymes and ubiquitin receptors to ubiquitylation and in the proteasomal degradation of regulatory proteins. We would like to know what type of protein-protein interactions assist in the proper functioning of the APC/C and the proteasome, what is the mechanism of polyubiquitin chain assembly on substrates and how these tagged proteins are escorted and recognized by the 26S proteasome.
In our work, we use the excellent model organism, the fruit fly, Drosophila melanogaster, which permits combined exploitation of genetic, molecular and cell biological techniques.
PROJECT 3. Investigating the role of transcription factors and chromatin modifiers
(supervisor: Imre Boros)
Transcription of eukaryotic genes is a multistep process that involves the interaction of a large number of functionally different protein factors and requires the ordered assembly of giant multiprotein complexes. In recent years the important role of chromatin structure in transcription regulation has been recognized and with that chromatin modifying complexes came into the focus of transcription related research. It is hoped that a better understanding of the role of functionally distinct classes of transcription regulatory proteins, among them those which modify histones to alter gene accessibility, is a key for deciphering why and how specific cellular processes are de-regulated in diseases.
In joint laboratories located at the BRC and at the Biochemistry and Molecular Biology Department of Szeged University we use biochemical and genetic approaches to characterize protein complexes which acetylate specific lysine residues of nucleosomal histones. Our work focuses on the role of ADA adaptor subunits of Drosophila histone acetyltransferase (HAT) complexes, SAGA and ATAC, which share the GCN5 acetyltransferase subunit. We are interested in learning that what types of interactions within and between chromatin modifying complexes play roles in determining modifications of specific histone residues. Revealing those protein-protein interactions might provide means to interfere with them under conditions when chromatin modifications open ways to deleterious changes in gene expression.
Cell cycle regulation:
Fu, J., Lipinszki, Z., Rangone, H., Min, M., Mykura, C., Chu, J., Schneider, S., Dzhindzhev, N. S., Riparbelli, M. G., Callaini, G., and Glover, D. M. Conserved molecular interactions in centriole-to-centrosome conversion. Nat Cell Biol (doi:10.1038/ncb3274). (2015)
Haider S, Lipinszki Z, Przewloka MR, Ladak Y, D'Avino PP, Kimata Y, Lio' P, Glover DM. DAPPER: a data-mining resource for protein-protein interactions. BioData Min. 2015 Sep 24;8:30. (2015)
Chen CC, Bowers S, Lipinszki Z, Palladino J, Trusiak S, Bettini E, Rosin L, Przewloka MR, Glover DM, O'Neill RJ, Mellone BG. Establishment of Centromeric Chromatin by the CENP-A Assembly Factor CAL1 Requires FACT-Mediated Transcription. Dev Cell. 2015 Jul 6;34(1):73-84. (2015)
Lipinszki Z , Lefevre S , Savoian MS , Singleton MR , Glover DM , Przewloka MR. Centromeric binding and activity of Protein Phosphatase 4. Nat Commun. 2015 Jan 6;6:5894. (2015)
Kovács L, Nagy O, Pál M, Udvardy A, Popescu O, Deák P. Role of the deubiquitylating enzyme DmUsp5 in coupling ubiquitin equilibrium to development and apoptosis in Drosophila melanogaster. PLoS One. 2015 Mar 25;10(3):e0120875. (2015)
Dzhindzhev NS, Tzolovsky G, Lipinszki Z, Schneider S, Lattao R, Fu J, Debski J, Dadlez M, Glover DM. Plk4 phosphorylates Ana2 to trigger Sas6 recruitment and procentriole formation. Curr Biol. 2014 Nov 3;24(21):2526-32. (2014).
Lipinszki Z, Wang P, Grant R, Lindon C, Dzhindzhev NS, D'Avino PP, Przewloka MR, Glover DM, Archambault V. Affinity purification of protein complexes from Drosophila embryos in cell cycle studies. Methods Mol Biol. 2014;1170:571-88. (2014)
Lipinszki Z, Klement E, Hunyadi-Gulyas E, Medzihradszky KF, Márkus R, Pál M, Deák P, Udvardy A: A novel interplay between the ubiquitin-proteasome system and serine proteases during Drosophila development. Biochem J. 454, 571-583. (2013)
Lipinszki Z, Kovács L, Deák P, Udvardy A: Ubiquitylation of Drosophila p54/Rpn10/S5a Regulates Its Interaction with the UBA–UBL Polyubiquitin Receptors. Biochemistry 51, 2461–2470. (2012)
Nagy O, Pál M, Udvardy A, Shirras C.A.M, Boros I, Shirras A.D. and Deák P: lemmingA encodes the Apc11 subunit of the APC/C in Drosophila melanogaster that forms a ternary complex with the E2-C type ubiquitin conjugating enzyme, Vihar and Morula/Apc2. Cell Division 7(1), 9. (2012)
Lipinszki Z, Pál M, Nagy O, Deák P, Hunyadi-Gulyás É, Udvardy A: Overexpression of Dsk2/dUbqln results in severe developmental defects and lethality in Drosophila melanogaster that can be rescued by overexpression of the p54/Rpn10/S5a proteasomal subunit. FEBS J. 278, 4833-4844. (2011)
Pál M., Nagy O., Ménesi D., Udvardy A. and Deák P: Structurally related TPR subunits contribute differently to the function of the anaphase promoting complex in Drosophila melanogaster. Journal of Cell Science 120, 3238-3248. (2007)
Pankotai T, Zsindely N, Vamos EE, Komonyi O, Bodai L, Boros IM Functional characterization and gene expression profiling of Drosophila melanogaster short dADA2b isoform-containing dSAGA complexes BMC GENOMICS 14:44 DOI: 10.1186/1471-2164-14-44. 2013
Zencir S, Sike A, Dobson MJ, Ayaydin F, Boros I, Topcu Z, Identification of transcriptional and phosphatase regulators as interaction partners of human ADA3, a component of histone acetyltransferase complexes BIOCHEMICAL JOURNAL 450 pp. 311-320. 2013
E Vamos E, Boros IM. The C-terminal domains of ADA2 proteins determine selective incorporation into GCN5-containing complexes that target histone H3 or H4 for acetylation. FEBS Letters 586(19) pp: 3279-3286. 2012
Pankotai T, Popescu C, Martin D, Grau B, Zsindely N, Bodai L, Tora L, Ferrús A, Boros I. Genes of the ecdysone biosynthesis pathway are regulated by the dATAC histone acetyltransferase complex in Drosophila. MOL. CELL. BIOL. 30(17) pp:4254-4266. 2010
Schauer T, Tombacz I, Ciurciu A, Komonyi O, Boros IM Misregulated RNA Pol II C-terminal domain phosphorylation results in apoptosis CELLULAR and MOLECULAR LIFE SCI. 66(5) pp: 909-918. 2009