PRDM paralogs antagonistically balance Wnt/β-catenin activity during craniofacial chondrocyte differentiation

Cranial neural crest cell (NCC)-derived chondrocyte precursors undergo a dynamic differentiation and maturation process to establish a scaffold for subsequent bone formation, alterations in which contribute to congenital birth defects. Here, we demonstrate that transcription factor and histone methyltransferase proteins Prdm3 and Prdm16 control the differentiation switch of cranial NCCs to craniofacial cartilage. Loss of either paralog results in hypoplastic and disorganized chondrocytes due to impaired cellular orientation and polarity. We show that these proteins regulate cartilage differentiation by controlling the timing of Wnt/beta-catenin activity in strikingly different ways: Prdm3 represses whereas Prdm16(-/-) activates global gene expression, although both act by regulating Wnt enhanceosome activity and chromatin accessibility. Finally, we show that manipulating Wnt/pcatenin signaling pharmacologically or generating prdm3(-/-);prdm16 (-/-) double mutants rescues craniofacial cartilage defects. Our findings reveal upstream regulatory roles for Prdm3 and Prdm16 in cranial NCCs to control Wnt/beta-catenin transcriptional activity during chondrocyte differentiation to ensure proper development of the craniofacial skeleton.

Automated summary

This study demonstrates that transcription factors and histone methyltransferase proteins Prdm3 and Prdm16 play crucial roles in the differentiation switch of cranial neural crest cells (NCCs) to craniofacial cartilage. The loss of either protein leads to abnormal chondrocyte development, which is regulated by controlling the timing of Wnt/beta-catenin activity and chromatin accessibility. Manipulating Wnt/beta-catenin signaling or generating double mutants of prdm3(-/-) and prdm16(-/-) can rescue craniofacial cartilage defects.