Oct4 and Its Pseudogenes Confuse Stem Cell Research

Summary Octamer-binding transcription factor 4 ( Oct4 ) encodes a POU-domain transcription factor (Scholer et al., 1990). The gene is specifically expressed in embryonic stem (ES) cells but can also be detected in adult stem cells such as bone marrow-derived mesenchymal stem cells (Pochampally et al., 2004). Expression of Oct4 is downregulated during stem cell differentiation. Oct4 plays a critical role in maintaining pluripotency and self-renewal of ES cells (Niwa et al., 2000; Pesce and Scholer, 2001), but its utility as a marker of pluripotency has been challenged recently by studies suggesting that it is expressed in a variety of differentiated cells, including peripheral blood mononuclear cells (PBMCs) (Tai et al., 2005; Zangrossi et al., 2007). However, detection of Oct4 expression by RT-PCR could be prone to artifacts generated by pseudogene transcripts. We therefore have analyzed the sequences of human Oct4 and its pseudogenes and designed PCR primers that can avoid false positive detection of Oct4 expression.