Transcriptional regulation in embryonic stem cells.

Transcriptional regulation is a pivotal process that confers cellular identity and modulates the biological activities within a cell. In embryonic stem cells (ESCs), the intricate interplay between transcription factors and their targets on the genomic template serves as building blocks for the transcriptional network that governs self-renewal and pluripotency. At the heart of this complex network is the transcription factor trio, Oct4, Sox2 and Nanog, which constitute the ESC transcriptional core. Regulatory mechanisms such as autoregulatory and feedforward loops support the ESC transcriptional framework and serve as homeostatic control for ESC maintenance. Large-scale studies such as loss of function RNAi screens and transcriptome analysis have led to the identification of more players that support pluripotency. In addition, genome-wide localization studies of transcription factors have further unraveled the interconnectivity within the ESC transcriptional circuitry. Transcription factors also work in concert with epigenetic factors and together, this crosstalk between transcriptional and epigenetic regulation maintains the homeostasis of ESC. This chapter provides an overview of the significance of transcriptional regulation in ESC and traces the recent advances made in dissecting the ESC transcriptional regulatory network.