OCT4 is a key transcription factor in maintaining the pluripotency and self-renewal of embryonic stem (ES) cells. Human OCT4 gene can generate three mRNA isoforms (OCT4A, OCT4B and OCT4B1) by alternative splicing and four protein isoforms (OCT4A, OCT4B-265, OCT4B-190 and OCT4B-164) by alternative splicing or alternative translation initiation. OCT4A is a transcription factor responsible for the stemness of ES cells, while the function of OCT4B protein isoforms is still not clear. We have previously reported that OCT4B-190 functioned in cell stress response. Here we present another product of OCT4 gene, OCT4B-265, is up-regulated under genotoxic stress in stem cells, and it may function in stress response through p53 signaling pathway. This work gives an insight into the novel function of OCT4B protein isoforms and helps us to understand the complex expression patterns and biological functions of OCT4 gene.

Keywords:OCT4;isoform;stem cells;genotoxic stress;apoptosis;p53