Transcriptomic and Accessibilty characterization of Wild type mouse Embryonic Stem Cells (mESCs), β-actin Knock out mESC and upon rescue with a nuclear localization signal β-actin

Pluripotency and lineage commitment in embryonic stem cells depend on coordinated regulation of chromatin architecture and extracellular matrix (ECM) signaling. Here, we identify nuclear β-actin as a key regulator linking these processes in mouse embryonic stem cells. Loss of β-actin disrupts core pluripotency factors, including Oct4 and Sox2, and causes broad transcriptional changes, while nuclear re-expression rescues these defects. Chromatin accessibility analysis revealed reduced accessibility at regulatory regions of pluripotency genes, consistent with impaired chromatin remodeling. β-actin depletion also altered ECM-related gene expression, matrix properties, and cellular biomechanics, leading to impaired self-renewal, skewed lineage specification, and defective differentiation, particularly reduced neuronal potential and increased mesodermal-like fate bias. In vivo, β-actin loss restricted teratoma growth and compromised tri-lineage differentiation. Together, these results define nuclear β-actin as an important regulator of chromatin accessibility, ECM-dependent signaling, and stem cell fate.