Abstract
Long non-coding RNAs (lncRNAs) are known players in the regulatory circuitry of the self-renewal in human embryonic stem cells (hESCs). However, most hESC-specific lncRNAs remain uncharacterized. Here we demonstrate that growth-arrest-specific transcript 5 (GAS5), a known tumour suppressor and growth arrest-related lncRNA, is highly expressed and directly regulated by pluripotency factors OCT4 and SOX2 in hESCs. Phenotypic analysis shows that GAS5 knockdown significantly impairs hESC self-renewal, but its overexpression significantly promotes hESC self-renewal. Using RNA sequencing and functional analysis, we demonstrate that GAS5 maintains NODAL signalling by protecting NODAL expression from miRNA-mediated degradation. Therefore, we propose that the above pluripotency factors, GAS5 and NODAL form a feed-forward signalling loop that maintains hESC self-renewal. As this regulatory function of GAS5 is stem cell specific, our findings also indicate that the functions of lncRNAs may vary in different cell types due to competing endogenous mechanisms.