Polyethylenimine‐cationized β‐catenin protein transduction activates the Wnt canonical signaling pathway more effectively than cationic lipid‐based transduction

The Wnt canonical signaling pathway is essential for the early development of eukaryotic organisms and plays a key role in cell proliferation, differentiation, and oncogenesis. Moreover, the Wnt canonical signaling pathway contributes to the self‐renewal of mouse hematopoietic stem cells (HSCs). Here, we demonstrate artificial activation of the Wnt canonical signaling pathway by β‐catenin protein transduction. Constitutively active β‐catenin protein was introduced into human embryonic kidney HEK‐293 cells using a polyethylenimine (PEI) cationization method, or with the BioPORTER protein transduction reagent. We have previously shown that modification with PEI effectively causes proteins to be internalized by living mammalian cells. PEI‐cationized, constitutively active β‐catenin protein was added to HEK‐293 cells, and induction of several Wnt/β‐catenin target genes was detected by real‐time PCR. However, using BioPORTER to introduce active β‐catenin did not activate the Wnt canonical signaling pathway. Introduction of eGFPNuc (enhanced green fluorescent protein variant containing a nuclear localization signal) into HEK‐293 cells using the BioPORTER reagent caused significant cell death, as determined by propidium iodide staining. In contrast, the PEI‐modified eGFPNuc did not impair survival of HEK‐293 cells. These results indicate that the Wnt canonical signaling pathway could be successfully activated by transduction of PEI‐cationized active β‐catenin, and the PEI‐cationization method is an effective and safe technology for protein transduction into mammalian cells.