Meis2 transcription factor regulates craniofacial osteogenesis via IGF signaling and cell adhesion

Cranial neural crest cell (cNCC)-derived mesenchyme must precisely integrate intrinsic transcriptional programs with localized signaling cues to orchestrate craniofacial skeletogenesis. While the transcription factor Meis2 is an essential regulator of this process, the spatially defined cellular contexts and downstream effector pathways remain poorly characterized. Building upon previous single-cell transcriptomic evidence of Igf2 dysregulation, we employed spatial transcriptomics integrated with single-cell references to map the mesenchymal landscape in Meis2-deficient embryos during early ossification. This spatial mapping identified distinct chondro-osteoprogenitor niches and revealed a significant enrichment of the IGF2 signaling axis within mutant mesenchymal compartments. We validated these spatial expression patterns in vivo, confirming the localized upregulation of Igf2 in Meis2-deficient osteo-chondroprogenitors. Functional in vitro assays demonstrated that IGF signaling is a potent modulator of cNCC-derived mesenchymal differentiation. Exogenous IGF2 enhanced osteogenic potential, whereas inhibition of the IGF1 receptor (IGF1R) significantly attenuated osteogenesis as measured using ALP activity. Furthermore, the impaired bone formation in Meis2 mutants correlated with disrupted cell adhesion dynamics. Collectively, these findings establish the importance of IGF2 signaling during embryonic craniofacial ossification and provide a mechanistic link between Meis2 loss, altered cell adhesion, and dysregulated osteogenic differentiation.