Genomic locus of lncRNA-Gm26793 forms an inter-chromosomal interaction with Cubn to ensure proper stem cell differentiation in vitro and in vivo.

Inter-chromosomal interactions play a crucial role in 3D genome organization, yet the organizational principles and functional significances remain elusive. In general, lncRNA loci and transcripts are frequently associated with transcriptional programs modulated by long-range chromatin interactions. Here, we identified a novel lncRNA named Gm26793, which is abundantly distributed in the primitive streak and mesodermal cells of embryonic day 7.5 mouse gastrula. Through genetic ablation of Gm26793, we observed a preferential responsiveness to primitive endoderm lineage during stem cell differentiation, as well as enhanced occurrence of transient and degenerative state cells in early mouse embryos when the cell fate segregates between epiblast and primitive endoderm. Mechanistically, we revealed that the genomic locus of Gm26793, rather than the lncRNA transcript or adjacent gene, governs the cell fate preference towards primitive endoderm. Concretely, Gm26793 locus (Chromosome 7) forms an inter-chromosomal molecular lock with Cubn (Chromosome 2) via CTCF, restraining the expression of Cubn and maintaining a natural epigenetic landscape, thus ensuring the proper lineage specification in vitro and in vivo. Overall, our study provides a clear paradigm that inter-chromosomal interaction collaborates with architectural factors to stabilize nuclear conformation and guarantee faithful gene expression during stem cell differentiation and mammalian embryogenesis.