Branched-chain Amino Acid Aminotransferase-1 Regulates Self-Renewal and Pluripotency of Mouse Embryonic Stem Cells through Ras Signaling

Embryonic stem cells (ESCs) can self-renew indefinitely and have the potential to differentiate into all cell types in the adult organism. Although the developmental plasticity of ESCs is mainly controlled by transcription factors, the intrinsic regulation of this process remains elusive. Here, using whole transcriptome RNA-sequencing analysis, we identified branched-chain amino acid aminotransferase-1 (Bcat1) as highly expressed in mouse ESCs. Further, deletion of the Bcat1 gene was found to impair the pluripotency and self-renewal of mouse ESCs and made cells more inclined to differentiate toward epiblast stem cells. Conversely, overexpression of Bcat1 in mouse ESCs resulted in robust self-renewal and the repression of differentiation. Mechanistically, Bcat1 regulates the expression of RAS protein activator like 1 (Rasal1), leading to activation of Ras-Erk/MAPK signaling axis, which controls the expression of a set of core transcription factors that maintain pluripotency and self-renewal. In summary, we identified for the first time that Bcat1 is essential for mouse ESCs self-renewal and pluripotency and that this effect is mediated by the Ras pathway. In order to figure out the possible regulator which maintains the mouse Embryonic stem cells pluripotency and self-renewal, we performed RNA-seq in WT (cultured in normal medium with 2i and lif) and differential (cultured in the medium lacking of 2i and lif for 7 days) E14 cells (in three replicates, using Illumina HiSeq-2000). By analyzing the RNA-seq data, we found Bcat1 was highly expressed in WT E14 cells and decreased in differential E14 cells, and further studies showed that Bcat1 is essential for maintaining mESCs self-renewal and pluripotency. Next, we want to figure out how Bcat1 functions in mESCs. Mouse Embryonic stem cells -E14 mRNA of wild type (WT) and Bcat1-/- were generated by deep sequencing, in two replicates, using Illumina HiSeq-2000.