Precise modulation of transcription factor levels identifies features underlying dosage sensitivity.

Area of Science:

• Genetics
• Developmental Biology
• Molecular Biology

Background:

• Transcriptional regulation is generally robust, yet human genetics highlights TF dosage sensitivity.
• TF dosage is crucial for craniofacial morphology and associated diseases.
• Quantitative studies on TF dosage effects in relevant ranges are limited.

Purpose of the Study:

• To quantitatively investigate TF dosage effects on gene regulation and craniofacial development.
• To develop a method for precise TF level modulation in human facial progenitor cells.
• To apply this method to SOX9, a TF implicated in craniofacial variation and Pierre Robin sequence (PRS).

Main Methods:

• Precisely modulating transcription factor (TF) levels in human facial progenitor cells.
• Analyzing the dosage sensitivity of SOX9-dependent regulatory elements (REs).
• Correlating RE responses with gene expression and craniofacial shape variation.

Main Results:

• Most SOX9-dependent REs are buffered against minor SOX9 dosage decreases.
• REs directly and primarily regulated by SOX9 exhibit heightened dosage sensitivity.
• Sensitive REs and genes preferentially impact chondrogenesis and PRS-like craniofacial phenotypes.

Conclusions:

• Specific REs and genes underlie phenotype sensitivity to TF dosage.
• Buffering mechanisms contribute to nonlinear dosage-to-phenotype relationships.
• Understanding TF dosage sensitivity is key for studying craniofacial development and disease.