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.

Jnk1−/− or jnk2−/− murine embryonic fibroblasts exhibit a significant potency in reprogramming to pluripotent stem cells.Figure optionsDownload high-quality image (201 K)Download as PowerPoint slide