The transcription factor Otx2 acts as a negative switch in the regulation of 
transition from naive to primed pluripotency in mouse pluripotent stem cells. 
However, the molecular features and function of porcine OTX2 have not been well 
elucidated in porcine-induced pluripotent stem cells (piPSCs). By studying 
high-throughput transcriptome sequencing and interfering endogenous OTX2 
expression, we demonstrate that OTX2 is able to downgrade the self-renewal of 
piPSCs. OTX2 is highly expressed in porcine brain, reproductive tissues, and 
preimplantation embryos, but is undetectable in fibroblasts and most somatic 
tissues. However, the known piPSC lines reported previously produced different 
levels of OTX2 depending on the induction procedures and culture conditions. 
Overexpression of porcine OTX2 can reduce the percentage of alkaline 
phosphatase-positive colonies and downregulate NANOG and OCT4 expression. In 
contrast, knockdown of OTX2 can significantly increase endogenous expressions of 
NANOG, OCT4, and ESRRB, and stabilize the pluripotent state of piPSCs. On the 
other hand, NANOG can directly bind to the OTX2 promoter as shown in ChIP-seq 
data and repress OTX2 promoter activity in a dose-dependent manner. These 
observations indicate that OTX2 and NANOG can form a negative feedback circuitry 
to regulate the pluripotency of porcine iPS cells.