Tex19: a germ cell-specific gene associated with pluripotency

Abstract

The establishment of the mammalian germline is a critical event during embryogenesis, producing a population of cells that will give rise to the gametes in the adult organism. Germ cells are the only population of cells in the adult organism shown to retain pluripotency - the ability to differentiate into all the different germ layers of the embryo. This property is shared with embryonic stem cells and tumourderived embryonal carcinoma cells, and the molecular mechanisms underpinning pluripotency are likely to be similar in all three systems. The core circuitry of transcription factors required to establish and maintain pluripotency is relatively well characterised. However, many of these important transcription factors also regulate a large number of genes involved in processes other than transcription, some of which may also play an important role in maintaining stem cell plasticity. Understanding the entire molecular basis of pluripotency will improve the use of ES cells as a model system for differentiation and development, enhance the therapeutic potential of stem cells and provide insights into the mechanisms of tumourigenesis. Testis Expressed Gene 19 has been identified in screens for genes expressed in spermatogonia, embryonic stem cells, and for targets of translational regulation by the germ cellspecific protein Dazl. The work presented here characterises the expression pattern of Texl9 in the gonads and stem cells, establishing a correlation between the expression of Texl9 and pluripotent potentiality. A human homologue of Texl9 is found to be expressed in stem cells and cancer, and the evolution of the gene family in mammals is investigated. Finally, the function of Tex19 and its relationship with Dazl is also investigated.