Ablation ofMaxexpression induces meiotic onset in sexually undifferentiated germ cells

Abstract

AbstractMeiosis is a specialized type of cell division that occurs only in germ cells physiologically. We have previously demonstrated that MYC-associated factor X (MAX) is involved in blocking ectopic and precocious meiotic onsets in embryonic and germline stem cells, respectively, as a central component of the PRC1 subtype PRC1.6. In this study, we investigated the role of theMaxgene in germ cellsin vivo. Our data revealed that mitotically active germ cell-specific disruption ofMaxwas coupled to meiotic onset in male and female germ cells. However, suchMax-null germ cells did not undergo meiotic processes progressively, but were stalled at its relatively early stages and eventually eliminated by apoptosis. Our data also revealed thatMax, which is generally known as an obligate heterodimerization partner for MYC and MXD transcription factors, showed high expression in sexually undifferentiated male and female germ cells, but female germ cells exhibited an abrupt decline in its expression at the timing of or immediately prior to physiological meiotic onset. Moreover, computational analyses identified the regulatory region that supported high levels ofMaxexpression in sexually undifferentiated germ cells.