Pluripotency Associated Genes are Reactivated by Chromatin Modifying Agents in Neurosphere Cells

¹ Institute for Biomedical Engineering, Department of Cell Biology, RWTH Aachen University Medical School, Pauwelsstrasse 30, 52074 Aachen, Germany; Helmholtz Institute for Biomedical Engineering, RWTH Aachen University, Pauwelsstrasse 20, 52074 Aachen, Germany
² Institute for Medical Radiation and Cell Research (MSZ), University of Würzburg, Versbacher Strasse 5, 97078 Würzburg, Germany
³ In vitro Differentiation Group, Institute of Plant Genetics and Crop Plant Research, Corrensstrasse 3, 06466 Gatersleben, Germany
⁴ Institute for Biomedical Engineering, Department of Cell Biology, RWTH Aachen University Medical School, Pauwelsstrasse 30, 52074 Aachen, Germany; Present address: Institute for Physiology, Charite - Campus Benjamin Franklin, Arnimallee 22, 14195 Berlin, Germany
⁵ Institute for Biomedical Engineering, Department of Cell Biology, RWTH Aachen University Medical School, Pauwelsstrasse 30, 52074 Aachen, Germany; Helmholtz Institute for Biomedical Engineering, RWTH Aachen University, Pauwelsstrasse 20, 52074 Aachen, Germany

^* To whom correspondence should be addressed. E-mail: martin.zenke{at}rwth-aachen.de.

	Abstract

Chromatin architecture in stem cells determines pattern of gene expression and thereby cell identity and fate. The chromatin modifying agents trichostatin A (TSA) and 5-Aza-2'-deoxycytidine (AzaC) affect histone acetylation and DNA methylation, respectively, and thereby influence chromatin structure and gene expression. In our previous work we demonstrated that TSA/AzaC treatment of neurosphere cells induces hematopoietic activity in vivo which is long-term, multilineage and transplantable. Here we have analyzed the TSA/AzaC induced changes in gene expression by global gene expression profiling. TSA/AzaC caused both up- and down-regulation of genes without increasing the total number of expressed genes. Chromosome analysis showed no hotspot of TSA/AzaC impact on a particular chromosome or chromosomal region. Hierarchical cluster analysis revealed common gene expression pattern between neurosphere cells treated with TSA/AzaC, embryonic stem (ES) cells and hematopoietic stem cells (HSC). Furthermore, our analysis identified several stem cell genes and pluripotency associated genes that are induced by TSA/AzaC in neurosphere cells, including CD34, CD133, Oct4, Nanog, Klf4, Bex1 and the Dppa family members Dppa2, 3, 4 and 5. Sox2 and c-Myc are constitutively expressed in neurosphere cells. We propose a model where TSA/AzaC by removal of epigenetic inhibition induces the reactivation of several stem cell and pluripotency associated genes and their coordinate expression enlarges the differentiation potential of somatic precursor cells.