The E3 ubiquitin ligase RNF220 maintains hindbrainHoxexpression patterns through regulation of WDR5 stability

The spatial and temporal linear expression ofHoxgenes establishes a regionalHoxcode, which is crucial for the antero-posterior (A-P) patterning, segmentation, and neuronal circuit development of the hindbrain. RNF220, an E3 ubiquitin ligase, is widely involved in neural developmentviatargeting of multiple substrates. Here, we found that the expression ofHoxgenes in the pons was markedly up-regulated at the late developmental stage (post-embryonic day E15.5) inRnf220^−/−andRnf220^+/−mouse embryos. Single-nucleus RNA-seq analysis revealed differentHoxde-repression profiles in different groups of neurons, including the pontine nuclei (PN). TheHoxpattern was disrupted and the neural circuits were affected in the PN ofRnf220^+/−mice. We showed that this phenomenon was mediated by WDR5, a key component of the TrxG complex, which can be polyubiquitinated and degraded by RNF220. Intrauterine injection of WDR5 inhibitor (WDR5-IN-4) and genetic ablation ofWdr5inRnf220^+/−mice largely recovered the de-repressedHoxexpression pattern in the hindbrain. In P19 embryonal carcinoma cells, the retinoic acid inducedHoxexpression was further stimulated byRnf220knockdown, which can also be rescued byWdr5knockdown. In short, our data suggest a new role of RNF220/WDR5 inHoxpattern maintenance and pons development in mice.