Neural crest cells require Meis2 for patterning the mandibular arch via the Sonic hedgehog pathway

Area of Science:

• Developmental biology
• Genetics
• Craniofacial development

Background:

• Cranial neural crest cells (cNCCs) are vital for craniofacial development, forming bone, cartilage, and influencing other tissues.
• Meis2 is a transcription factor with a known role in development, but its specific function in cNCCs was unclear.

Purpose of the Study:

• To investigate the role of the transcription factor Meis2 in cranial neural crest cells.
• To understand Meis2's contribution to pharyngeal arch patterning and craniofacial development.

Main Methods:

• Conditional inactivation of the Meis2 gene in cNCCs using mouse models.
• Analysis of gene expression patterns and craniofacial morphology in mutant mice.

Main Results:

• Conditional Meis2 inactivation in cNCCs led to impaired pharyngeal arch 1 (PA1) patterning.
• Loss of Meis2 disrupted Sonic hedgehog signaling and altered expression of key developmental markers (Hand1/2, Dlx5, Barx1, Gsc).
• Mutant mice exhibited hypoplastic tongue and ectopic mandible ossification, resulting in craniofacial defects.

Conclusions:

• Meis2 is essential for proper molecular specification and patterning of PA1 by cNCCs.
• Meis2-dependent craniofacial development is critical, as defects mimic human syndromes associated with Meis2 mutations.