JNK1 and 2 play a negative role in reprogramming to pluripotent stem cells by suppressing Klf4 activity

•Activation of JNKs is induced by LIF withdrawal.•JNK1 or JNK2 phosphorylates Klf4 at threonines 224 and 225.•JNK1 or JNK2 binds with Klf4.•Phosphorylation of Klf4 inhibits Klf4 transcription and transactivation activity.•jnk1−/− or jnk2−/− MEFs exhibit a substantial potency in increasing the number of iPS colonies.

Embryonic stem (ES) cells are pluripotent cells with the capacity for unlimited self-renewal or differentiation. Inhibition of MAPK pathways enhances mouse ES cell pluripotency characteristics. Compared to wildtype ES cells, jnk2−/− ES cells displayed a much higher growth rate. To determine whether JNKs are required for stem cell self-renewal or differentiation, we performed a phosphorylation kinase array assay to compare mouse ES cells under LIF + or LIF − culture conditions. The data showed that activation of JNKs was induced by LIF withdrawal. We also found that JNK1 or 2 phosphorylated Klf4 at threonines 224 and 225. Activation of JNK signaling and phosphorylation of Klf4 inhibited Klf4 transcription and transactivation activity. Importantly, jnk1−/− and jnk2−/− murine embryonic fibroblasts (MEFs) exhibited a significantly greater potency in the ability to increase the number of iPS colonies compared with jnk wildtype MEFs. Overall, our results demonstrated that JNK1 and 2 play a negative role in reprogramming to pluripotent stem cells by suppressing Klf4 activity.

Graphical abstractJnk1−/− or jnk2−/− murine embryonic fibroblasts exhibit a significant potency in reprogramming to pluripotent stem cells.Figure optionsDownload full-size imageDownload high-quality image (201 K)Download as PowerPoint slide