Oct-4: Lessons of totipotency from embryonic stem cells

The Oct-4 transcription factor is expressed in embryonic stem cells and ger m cells of the mouse embryo. Cells that are driven into embryonic and extra embryonic somatic differentiation lose Oct-4 expression. Oct-4 is crucial f or the maintenance of the totipotency of embryonic cells at early developme ntal stages as demonstrated recently by homologous recombination. Since dur ing embryogenesis Oct-4 is restricted to germ cells, it is possible that it plays a key role for the germline lineage by preventing differentiation of these cells during gastrulation. Thus, Oct-4 appears to be a key regulator of totipotency during the life cycle of mammals. Copyright (C) 1999 S. Kar ger AG, Basel.