EHMT2 Controls Neural Crest-Derived Craniofacial Development but is Dispensable in Limb Development

Area of Science:

• Epigenetics and Developmental Biology
• Skeletal Biology
• Chromatin Regulation

Background:

• Histone modifications, like H3K9 methylation by EHMT2, regulate gene expression and chromatin structure.
• EHMT2 (G9A) is a histone methyltransferase involved in transcriptional regulation.
• While global EHMT2 knockout is lethal, its tissue-specific roles in development are less understood, particularly in skeletal development.

Purpose of the Study:

• To investigate the lineage-specific role of EHMT2 in skeletal development.
• To determine EHMT2's function in neural crest-derived and mesoderm-derived skeletal progenitors.

Main Methods:

• Conditional inactivation of the mouse Ehmt2 gene using Wnt1-Cre and Prx1-Cre lines.
• Analysis of craniofacial and limb skeletal development in knockout mouse models.
• Transcriptomic analysis of affected neural crest cells.

Main Results:

• Loss of EHMT2 in neural crest cells caused postnatal growth failure and craniofacial defects, including delayed ossification and jaw malformations.
• Transcriptomic analysis revealed disrupted chromatin networks, reduced proliferation genes, and increased inflammation in neural crest cells lacking EHMT2.
• Inactivation of EHMT2 in mesodermal progenitors had minimal impact on bone development, bone mass, or osteoblast function.

Conclusions:

• EHMT2 is essential for skeletal development in neural crest-derived lineages.
• Distinct progenitor populations show differential dependency on EHMT2 for bone development.
• These findings highlight a lineage-specific requirement for EHMT2 in craniofacial skeletal formation.