Research - Institute of Genetics - Mammalian Cell Research Unit - Laboratory of Embryonic and Induced Pluripotent Stem Cells

Melinda PIRITY
senior research associate

Izabella BAJUSZ research associate
Gergő KOVÁCS research associate
Krisztina DUDÁS scientific administrator
SURYA Henry Ph.D. student
Viktória SZABÓ Ph.D. student
Enikő SUTUS Ph.D. student
Bertalan TAKÁCS B.Sc student


Pluripotency and Differentiation in Embryos and Stem Cells

Embryonic Stem (ES) cells can proliferate indefinitely in culture (self-renewal) and differentiate into cells of all three germ layers (pluripotency). ES cells derive from the Inner Cell Mass (ICM) of the early stage mammalian embryos but can also be generated by reprogramming somatic cells (Induced Pluripotent Stem Cells; iPSCs). Furthermore, ES cells can re-enter the developing embryo and contribute to all cell types of the embryo including germ line (germ line transmission). Importantly, ES cells can form three dimensional aggregates called embryoid bodies (EBs) and able to differentiate into all cell types of the body including cardiomyocytes (CMCs) or different cell types of the central nervous system (CNS).

The Role of the Polycomb Protein Rybp in Stem Cell Self-Renewal and Differentiation

Our laboratory is using ES cells in order to model development and differentiation. Our interest lies in the generation and use of stem cell based models to understand basic mechanisms of gene regulation leading to disease pathogenesis. Especially, our laboratory is focusing on the transcriptional regulator gene rybp (Ring1- and YY1-Binding Protein; or also known as DEDAF (Death Effector Domain Associated Factor), UniGene Mm.321633; MGI:1929059) and its protein product (Rybp), which belongs to the polycomb group (PcG) protein family. PcG proteins are unique in that they maintain either repressed or activated chromatin configurations, respectively, for extended periods of time. This feature makes them particularly important in the maintenance of ‘‘cellular memory’’ during lineage differentiation and also in adult tissues.

Our previous work showed that Rybp appears to be selectively upregulated in distinct structures and cell types of the developing eye and the CNS and, may also play a role in more mature neurons. Alterations in Rybp dosage induced striking neural tube defects (NTDs). We previously derived ES cells bearing homozygously (rybp-/-) and heterozygously (rybp+/-) disrupted rybp genes, thereby providing a molecular genetic approach to assess the dosage dependent role of rybp in differentiation processes. We have also derived transgenic cell lines that overexpress Rybp (RybpTg). Since the mutant cell lines express Rybp in different level (from null to overexperessed version) these cell lines, provide a unique resource to elucidate the dosage dependent role of rybp in the process of differentiation. Our main focus in to determine the role of Rybp in (i) neural and (ii) cardiac lineage commitment.

The work, currently undergoing in our laboratory aims to contribute to a better understanding of signal transduction pathways governing mammalian heart and CNS development. It will also improve our knowledge on the generation, maintenance and manipulation of stem cell derived cardiomyocytes and neural tissues. Understanding the genetic underpinnings of cardiac/neural development has important implications not only for understanding congenital heart or neurodegenerative disease, but also for the possibility of cardiac/neural repair through genetic reprogramming of non-cardiac/neural cells to a cardiogenic/neurogenic fate. Unique properties of the ES and iPS cells make them exceptionally valuable for future cell replacement therapies, drug discovery and regenerative medicine.

Selected publications

Kovacs G, Szabo V, Pirity MK. (2016) Absence of Rybp Compromises Neural Differentiation of Embryonic Stem Cells. Stem Cells International. 2016; 2016:4034620.

Ujhelly O, Szabo V, Kovacs G, Vajda F, Mallok S, Prorok J, Acsai K, Hegedus Z, Krebs S, Dinnyes A, Pirity MK. Lack of Rybp in Mouse Embryonic Stem Cells Impairs Cardiac Differentiation. Stem Cells and Development 2015 Sept, 24(18):2193-205

Pajer K, Nemes C, Berzsenyi S, Kovács KA, Pirity MK, Pajenda G, Nógrádi A, Dinnyés A. Grafted murine induced pluripotent stem cells prevent death of injured rat motoneurons otherwise destined to die. Exp Neurol. 2015 Jul; 269:188-201

Bajusz I, Sipos L, Pirity MK. Nucleotide Substitutions Revealing Specific Functions of Polycomb Group Genes. Mol Genet. Metab. 2015 Apr; 114(4):547-56

Rungarunlert S, Klincumhom N, Tharasanit T, Techakumphu M, Pirity MK, Dinnyes A. (2013) Slow Turning Lateral Vessel Bioreactor Improves Embryoid Body Formation and Cardiogenic Differentiation of Mouse Embryonic Stem Cells. Cell Reprogram. Oct;15(5):443-58

Klincumhom N, Pirity MK, Berzsenyi S, Ujhelly O, Muenthaison S, Rungarunlert S, Tharasanit T, Techakumphu M, Dinnyes A. (2012) Generation of neuronal progenitor cells and neurons from mouse sleeping beauty transposon-generated induced pluripotent stem cells. Cell Reprogram. 14(5):390-7

Pirity MK, Wang WL, Wolf LV, Tamm ER, Schreiber-Agus N, Cvekl A. (2007) Rybp, a polycomb complex-associated protein, is required for mouse eye development. BMC Dev Biol. Apr 30;7:39

Pirity M., Locker J., Schreiber-Agus N. (2005) Rybp/DEDAF is required for early post- implantation and for central nervous system development. Mol. Cell. Biol. 16:7193-7202