Identification of ID4-interacting proteins in cultured undifferentiated spermatogonia

ID4 belongs to a family of transcriptional regulators involved in stem cell function. ID family proteins act by binding and inhibiting activity of basic-HLH (bHLH) transcription factors, including E-proteins and class II factors. ID function is also mediated through interaction with non-bHLH proteins. Spermatogonial stem cells (SSCs) are found within a population of undifferentiated spermatogonia in the testis and are essential for the sustained production of sperm over the lifespan. It is reported that ID4 is involved in SSC maintenance but the downstream targets of ID4 in SSCs are unclear. To gain insight into the function of ID4 in SSCs we identified interacting partners in cultures of mouse undifferentiated spermatogonia by immunoprecipitation using a specific ID4 antibody and mass spectrometry analysis.