Dissecting the Role of PrPc’s Partner Stip1 in Early Embryogenesis via Wnt Signaling

Mouse embryonic stem cells (mESCs) are a powerful model for studying early development due to their pluripotency, the ability to differentiate into all three embryonic germ layers. This state is tightly controlled by intracellular signaling and external developmental cues. Among these, cell surface signaling complexes are particularly important with the cellular prion protein (PrPc) acting as a scaffold for various partners. One such partner, Stress-Inducible Protein 1 (Stip1/Hop), is a co-chaperone known to interact with PrPc, modulate Wnt signaling, promote neuritogenesis, and whose deletion causes embryonic lethality in mice. To elucidate the role of Stip1 and its interplay with PrPc in early embryogenesis, we used mESCs with modulated Stip1 levels to examine their potential involvement in Wnt signaling. We employed RT-qPCR and Western blotting to assess Wnt pathway and pluripotency markers under basal conditions and following pharmacological modulation, and used immunofluorescence to monitor changes in protein localization. Preliminary findings show that both Stip1-overexpressing and heterozygous cells exhibit similar responses  to Wnt pathway modulation, with changes in canonical targets such as activated β-catenin, c-Myc, and Axin1. However, no significant differences were seen in core pluripotency markers. These results suggest that Stip1 modulates Wnt signaling independently of pluripotency maintenance, supporting  a potential role in bridging  proteostasis and developmental signaling. Notably, reduced Stip1 expression led to a significant increase in PrPc expression at both transcript and protein levels, indicating a possible co-regulatory  relationship  between these interacting proteins during early embryonic development.