Liquid-liquid phase separation (LLPS) of KLF4 in the nucleus to promote transcription of IRF4.

Our previous work showed that p-STAT3-stabilized KLF4 undergoes nuclear liquid-liquid phase separation (LLPS). However, the upstream mechanisms controlling which genomic regions KLF4 binds during cDC2 differentiation remained undefined. Since transcription is often associated with transcription factor condensates, we aimed to identify downstream genes regulated by P2Y14R-mediated KLF4 condensates following UDPG stimulation.We performed CUT&Tag with a KLF4 antibody. Results indicated that UDPG stimulation increased KLF4 binding peaks in wild-type (WT) cDC2s, while P2Y14R knockout (KO) cells showed strongly reduced KLF4 binding. This suggests that UDPG activates the P2Y14R-JAK2-p-STAT3 pathway, promoting nuclear entry of p-STAT3, which enhances KLF4 LLPS, increases Irf4 expression, and thereby drives cDC2 differentiation.