Effects of Klf4 and c-Myc Knockdown on Pluripotency Maintenance in Porcine Induced Pluripotent Stem Cell

Document Type : Original Article

Authors

1 Division of Physiology, Livestock Research Institute, Council of Agriculture, Executive Yuan, Tainan, Taiwan;Department of Animal Science, National Chung Hsing University, Taichung, Taiwan

2 Division of Physiology, Livestock Research Institute, Council of Agriculture, Executive Yuan, Tainan, Taiwan

3 Hsinchu Branch, Livestock Research Institute, Council of Agriculture, Executive Yuan, Hsinchu, Taiwan

4 Division of Physiology, Livestock Research Institute, Council of Agriculture, Executive Yuan, Tainan, Taiwan;4Institute of Biotechnology, National Cheng Kung University, Tainan, Taiwan ;5Institute of Biotechnology, Southern Taiwan

Abstract

Objective
The importance of Oct4 and Sox2 in maintaining pluripotency and self-renewal is well-understood, but the functions of Klf4 and c-Myc has not been fully investigated. In the present study, we attempted to determine the roles of Klf4 and c-Myc on pluripotency maintenance of porcine induced pluripotent stem (piPS) cells.
Materials and Methods
In this experimental study, we performed short hairpin RNA (shRNA) to knock down the Klf4 and c-Myc functions of piPS cells and examined pluripotency markers and teratoma formation to evaluate piPS cell pluripotency. The shRNA-Klf4 and shRNA-c-Myc vectors containing a reporter gene, TagFP635, were transfected into piPS cells by lentivirus infection. The piPS cells fully expressing infrared fluorescence were selected to confirm gene knockdown of Klf4 and c-Myc reverse transcription-polymerase chain reaction (RT-PCR). Next, for pluripotency evaluation, expression of pluripotency markers was detected by immunocytochemical staining, and capability of teratoma formation was investigated by piPS cell transplantation into nonobese diabetic-severe combined immunodeficiency (NOD-SCID) mice.
Results
Our findings indicated that Klf4 and c-Myc functions of piPS cells were knocked down by shRNA transfection, and knockdown of Klf4 and c-Myc functions impaired expression of pluripotency markers such as Oct4, AP, SSEA-3, SSEA-4, TRA-1-6, and TRA-1-81. Furthermore, piPS cells without Klf4 and c-Myc expression failed to form teratomas.
Conclusion
The pluripotency of piPS cells are crucially dependent upon Klf4 and c-Myc expression. These findings, suggesting potential mechanisms of Klf4 and c-Myc contribution to piPS cell formation, have important implications for application, regulation, and tumorigenesis of piPS cells.

Keywords