Transposable elements (TEs) occupy nearly half of the genome and drive developmental innovation, yet the mechanisms of silencing long terminal repeats (LTRs) remain incompletely understood. We demonstrate that methyltransferase-like 3 deficiency reverts naive human embryonic stem cells (hESCs) to a totipotent-like state with reactivation and chromatin resetting of 8C-associated genes, eRNAs, and LTRs, particularly ERV1 and ERVL-MaLR. Moreover, m6A on primate-specific L1PA is found to be essential. Mechanistically, L1PA binds 8C-associated LTRs and eRNAs and regulates chromatin through RNA-scaffold complexes with chromatin regulators, where m6A directs protein-binding preference. In naive hESCs, m6A on L1PA suppresses EP300 binding to ERV1 and enhances KAP1 binding to ERVL-MaLR, thereby restricting LTR activity. In parallel, the m6A-L1PA axis or m6A on eRNAs limits EP300/H3K27ac occupancy at 8C enhancers. Our findings reveal a conserved mechanism in which humans and mice employ species-specific long interspersed nuclear element-1 subfamilies with m6A to regulate LTR activity, underscoring the crucial role of transposons in RNA-chromatin crosstalk during cell fate transitions.
Keywords: RNA m(6)A methylation; human embryonic stem cells; pluripotency; totipotency; transposable elements.
Copyright © 2025 Elsevier Inc. All rights reserved.