Combinatorial CRISPR/Cas9 Approach to Elucidate a Far-Upstream Enhancer Complex for Tissue-Specific Sox9 Expression.

Area of Science:

• Genetics
• Developmental Biology
• Molecular Biology

Background:

• SRY-box 9 (SOX9) is a critical transcription factor for cartilage development.
• Acampomelic campomelic dysplasia (ACD) is linked to SOX9 haploinsufficiency due to upstream region disruptions, implying crucial enhancers exist in this area.
• The specific cis-acting enhancer regulating cartilage-specific SOX9 expression has not been identified.

Purpose of the Study:

• To identify distant cis-acting enhancers regulating cartilage-specific SOX9 expression.
• To elucidate the regulatory mechanisms underlying SOX9 expression in chondrogenesis.

Main Methods:

• Utilized CRISPR/Cas9 technologies for promoter-enhancer complex enrichment and next-generation sequencing.
• Employed SIN3A-dCas9-mediated epigenetic silencing.
• Generated enhancer deletion mice models.

Main Results:

• Identified a critical far-upstream cis-element regulating SOX9 expression.
• Discovered Stat3 as a trans-acting factor involved in cartilage-specific SOX9 regulation.
• Demonstrated the role of this element and Stat3 in skeletal development.

Conclusions:

• The identified cis-element and Stat3 are crucial for cartilage-specific SOX9 expression and skeletal development.
• This research provides a strategy for definitive ACD diagnosis.
• The findings offer insights into chromatin conformation and gene regulation relevant to skeletal disorders.