N Nature Cell Biology · Dec 03, 2025 A human epiblast model reveals dynamic TGFβ-mediated control of epithelial identity during mammalian epiblast development Pluripotency, the ability to generate all body cell types, emerges in a disorganized embryonic cell mass. After implantation, these cells form a columnar epithelium and initiate lumenogenesis. During gastrulation, some undergo epithelial-to-mesenchymal transition to form the primitive streak (PS). The signals controlling these events in humans are largely unknown. Here, to study them, we developed a chemically defined 3D model where conventional pluripotent stem cells self-organize into a columnar epithelium with a lumen, from which PS-like cells emerge. We show that early TGFβ family inhibition prevents epithelial identity, also in murine 3D embryo models and in embryos. ZNF398 acts downstream of TGFβ1, activating the epithelial master regulator ESRP1 while repressing mesenchymal factors CDH2 and ZEB2. After epithelium formation, TGFβ1 stimulation is dispensable for its maintenance. However, treatment via ACTIVIN—a distinct TGFβ family ligand—induces PS efficiently. Thus, signalling of the TGFβ family dynamically governs pluripotent epiblast epithelial identity. Embryonic stem cells Epithelial–mesenchymal transition Growth factor signalling biology
N Nature Cell Biology · Dec 02, 2025 Lineage-determining transcription factors constrain cohesin to drive multi-enhancer oncogene regulation Multiple enhancers, often separated by vast genomic distances, regulate key genes. However, how the folding of individual chromatin fibres enables cell-type-restricted multi-enhancer regulation remains unclear. Here, using acute protein degradation and time-resolved chromatin conformation capture in mantle cell lymphoma, we found that the B cell-lineage-determining factor EBF1 organizes multiple enhancers around sparsely distributed genes essential for B cell identity and oncogenesis. Time-resolved sub-diffraction optical tracing of more than 100,000 chromatin fibres further revealed diverse topological conformations that facilitate multi-enhancer interactions. Mechanistically, we discovered that enhancer positioning at local topological centres is required for promoter engagement, with EBF1 acting as a permeable barrier to loop-extruding cohesin at enhancers. Extending these findings to T cell leukaemia, we show that lineage-determining transcription factors such as EBF1 and TCF1 radially position enhancers within gene loci to enable multi-enhancer regulation of key oncogenes at the single-allele level. Epigenetics Oncogenes biology
N Nature Cell Biology · Dec 02, 2025 Karyopherins remodel the dynamic organization of the nuclear pore complex transport barrier Nuclear pore complexes (NPCs) mediate selective exchange of macromolecules between the nucleus and cytoplasm, but the organization of their transport barrier has been a matter of debate. Here we used high-speed atomic force microscopy, complemented with orthogonal in vitro and in vivo approaches, to probe the dynamic behaviour of the NPC central channel at millisecond resolution. We found that nuclear transport factors dynamically remodel intrinsically disordered phenylalanine-glycine (FG) domains tethered within the NPC channel, partitioning the barrier into two zones: a rapidly fluctuating annular region and a highly mobile central plug. Increased FG-repeat density in mutant NPCs dampened barrier dynamics and impaired transport. Notably, NPC-like behaviour was recapitulated in DNA origami nanopores bearing transport factors and correctly tethered FG domains but not in in vitro FG hydrogels. Thus, the rotationally symmetric architecture of NPCs supports a nanoscopic barrier organization that contrasts with many of the bulk properties of in vitro FG-domain assemblies. Atomic force microscopy Molecular biophysics Nuclear pore complex biology
N Nature Cell Biology · Dec 01, 2025 RASH3D19 mediates RAS activation through a positive feedback loop in KRAS-mutant cancer Therapeutic targeting of mutant KRAS pathways driving cancers is being actively investigated to identify feedback mechanisms responsible for the development of adaptive resistance to mutant KRAS inhibitors undergoing clinical trials. Here we report RASH3D19 as a mediator of RAS pathway activation through a positive feedback loop involving the KRAS–microRNA signalling axis. KRAS-induced miR-222 represses ETS1 expression and downstream transactivation of miR-301a leading to elevation of its target RASH3D19. RASH3D19 facilitates activation of RAS pathways by promoting dimerization and interaction of EGFR with the SOS2, GRB2, SHP2 and GAB1 complex. Genetic deletion of RASH3D19 in mutant KRAS-expressing cancer cells exhibits growth retardation in vitro, in vivo and sensitized pancreatic ductal adenocarcinoma and colorectal cancer cells, organoids and xenografts to mutant KRAS inhibitors, suppressing feedback reactivation of RAS pathways. Therapeutic targeting of RASH3D19 is expected to lead to tumour debulking and alleviating resistance to KRAS inhibitors in mutant KRAS-expressing cancers. Cancer therapeutic resistance Oncogenes Targeted therapies biology
