İNSAN SOMATİK HÜCRELERİNİN UYARILMIŞ PLÜRİPOTENT KÖK HÜCRELERE YENİDEN PROGRAMLANMASI SÜRECİNDE ARİLHİDROKARBON RESEPTÖRÜ SİNYALİZASYONUNDAKİ DEĞİŞİMLERİN İNCELENMESİ

Abstract

Sevindi S., Investigation of Changes in Arylhydrocarbon Receptor Signaling in the Reprogramming of Human Somatic Cells into Induced Pluripotent Stem Cells, Hacettepe University Graduate School of Health Sciences Department of Stem Cell Program Master Thesis, Ankara, 2023. Generation of induced pluripotent stem cells (iPSC) by reprogramming somatic cells in-vitro, offers significant opportunities for disease modeling and drug research. In the reprogramming process of the somatic cell with de-differentiation towards pluripotency, it is necessary to gain knowledge and experience to elucidate the effective mechanisms and to create optimal conditions. This thesis study was planned to investigate the changes in Arylhydrocarbon Receptor (AhR) signaling, which is a xenobiotic receptor and plays a key role in the regulation of cell fate, during reprogramming and culturing of iPSCs. Mesenchymal stem cells (MSCs) were used as source cells to investigate the changes in AhR signaling during reprogramming through the transfer of OSKM factors by electroporation of episomal plasmids. The morphological changes of the cells and AhR signaling-related gene/protein expressions, loss of somatic cell/MSC identity, mesenchymal-epithelial transition (MET) -related and pluripotency-related gene expressions were investigated during the first seven-day period of reprogramming and then at specified time intervals, and in mature iPSCs. Preliminary experiments were carried out with the use of AhR agonist (FICZ) and antagonist (StemRegenin-1). Upregulation of AhR and related molecules were noted during reprogramming process of MSCs towards pluripotency. On the other hand AhR gene expression was suppressed in characterized iPSCs when compared to the cells at reprogramming stage. This was associated with upregulated expression of AHRR and IDO-1 shown to increase with pluripotency. These preliminary findings suggested a possible regulatory role of AhR signaling in determining stemness and cell fate.