Heme oxygenase-1 gene is repressed by the essential pluripotent stem cell transcription factor Oct4

VICTORIA PETRONE; AYELEN TORO; CAMILA VAZQUEZ ECHEGARAY; CLAUDIA SOLARI; SOLEDAD COSENTINO; MARCOS FRANCIA; ELBA VAZQUEZ; ALEJANDRA GUBERMAN

Simposio; Simposio Fronteras en Biociencia 3; 2018

IBIOBA

Embryonic stem cells (ESCs) have the ability to differentiate into cells of all three germ layers andpossess several mechanisms that ensure genome stability avoiding the propagation of geneticdamage. Heme oxygenase (HO) is the limiting enzyme in the oxidative catabolism of the hemegroup, and particularly, the inducible isoform HO-1 is known by its antioxidant and antiapoptoticactivities. HO-1 action was deeply studied in multipotent stem cells, however, little is known aboutits gene regulation in pluripotent stem cells.We previously found that HO-1 was induced during ESCs differentiation, showing the opposedexpression pattern than pluripotent stem cells essential transcription factors (TFs), such as Nanog,Oct4 and Sox2. Based on these evidences, we aimed to study if HO-1 is regulated by these TFs. Inorder to achieve this, we first in silico analyzed HO-1 promoter region and found multiple putativebinding sites for Oct4 and Nanog. So, we next studied HO-1 gene regulation in ESC were these TFswere downregulated by a shRNA approach. We found that HO-1 mRNA levels analyzed by RT-qPCRincreased in ESCs transfected with shRNA targeting Oct4 respect to control cells transfected with acontrol shRNA (shGFP) or shRNA targeting Nanog, suggesting that Oct4 repress HO-1 in ESC.We then studied if HO-1 was modulated by Oct4 in a heterologous system where this TF can beinduced by doxycycline treatment, the cell line NIH Oct4-YPET generated by us. We found thatOct4 induction by doxycycline treatment reduced HO-1 gene expression respect to untreated cells,determined by immunofluorescence, Western blot and RT-qPCR, these last analyzed usingrandomized block design ANOVA and Tukey test.In summary, these findings indicate that pluripotency transcription factor Oct4 negativelymodulates HO-1 gene transcription.Keywords: pluripotent stem cells, HO-1, gene expression, transcriptional regulation.