Genetic background dependent modifiers of craniosynostosis severity.

Area of Science:

• Genetics
• Developmental Biology
• Molecular Biology

Background:

• Craniosynostosis, a birth defect, exhibits variable severity even with identical genetic mutations.
• Understanding the genetic and molecular basis of this phenotypic variation is crucial for effective treatment.

Purpose of the Study:

• To investigate the role of genetic background in modifying craniosynostosis severity.
• To identify pre-existing molecular differences that may predispose to or protect against craniosynostosis.

Main Methods:

• Backcrossed FGFR2+/C342Y mouse model of Crouzon syndrome onto C57BL/6 and BALB/c backgrounds.
• Compared transcriptome signatures of cranial tissues between different genetic backgrounds.
• Analyzed protein levels and signaling pathway activity (MAPK cascade).

Main Results:

• Coronal suture fusion occurred in C57BL/6 FGFR2+/C342Y mice but not BALB/c.
• Differential expression of craniosynostosis-associated transcription factors (Twist, En1, Runx2) between backgrounds.
• Transcriptome differences linked to calcium ion channels, angiogenesis, protein quality control, and cell stress response.
• Elevated FGFR2 and HSPA2 protein levels and ERK1/2 activity in C57BL/6 mice.
• Abnormal FGFR2 protein processing observed in FGFR2+/C342Y cells.

Conclusions:

• Genetic background significantly influences craniosynostosis phenotype severity.
• Differences in protein quality control mechanisms may underlie genetic epistasis in craniofacial development.
• These findings provide insights into the molecular basis of phenotypic variation in Crouzon syndrome.