DNA repair proteins cooperate with SOX2 in regulating the transition of human embryonic stem cells to neural progenitor cells.

SOX2, a well-established pluripotency factor supporting the self-renewal of pluripotent stem cells (PSCs), is also a crucial factor for maintaining the properties and functionalities of neural progenitor cells (NPCs). It regulates the transcription of target genes by forming complexes with its partner factors, but systematic comparison of SOX2 binding partners in human PSCs versus NPCs is lacking. Here, by deciphering and comparing the SOX2-protein interactomes in human embryonic stem cells (hESCs) versus the NPCs derived from them, we identified 23 proteins with high reproducibility that are most differentially associated with SOX2, of which 9 are DNA repair proteins (PARP1, PARP2, PRKDC, XRCC1, XRCC5, XRCC6, RPA1, LIG3, DDB1). Genetic knocking-down or pharmacological inhibiting two of the DNA repair proteins (PARP1 and PRKDC) significantly up-regulated certain NPC or ectodermal biomarkers that are transcriptionally-suppressed by the SOX2/DNA repair protein complexes. These findings point to a crucial role of DNA repair proteins in pluripotent state transition and neural induction.