Association between Triplex-Forming Sites of Cardiac Long Noncoding RNA GATA6-AS1 and Chromatin Organization

Area of Science:

• Genomics
• Molecular Biology
• Epigenetics

Background:

• Long noncoding RNAs (lncRNAs) regulate genome activity but their role in 3D genome organization is unclear.
• RNA-DNA triplexes are structural motifs formed by lncRNAs with genomic DNA.
• Topologically Associated Domains (TADs) are fundamental units of 3D genome architecture.

Purpose of the Study:

• To investigate the relationship between lncRNA-DNA triplex sites and 3D genome organization, specifically TADs.
• To determine the genomic positioning of triplex-forming sites of the cardiac lncRNA GATA6-AS1 relative to TADs and TAD boundaries.
• To explore potential interactions between GATA6-AS1, CTCF, and repeat elements in shaping 3D genome structure.

Main Methods:

• DBD-Capture-Seq was used to identify GATA6-AS1 triplex-forming sites.
• Hi-C data was utilized to define TADs and their boundaries.
• Computational prediction analysis was performed to assess CTCF binding site correlation with GATA6-AS1 triplex sites.
• Genomic locations of repeat elements were examined in relation to triplex sites.

Main Results:

• GATA6-AS1 triplex-forming sites were found to be non-randomly distributed within TADs, with a preference for TAD boundaries.
• CTCF binding sites, crucial for TAD formation, showed correlation with GATA6-AS1 binding sites.
• Expansion of repeat elements may facilitate GATA6-AS1 triplex formation across numerous genomic locations.
• Some triplex sites were located in regions with dynamic chromatin organization during cardiac differentiation.

Conclusions:

• lncRNA GATA6-AS1 triplex formation is spatially associated with TADs and their boundaries.
• lncRNA-DNA triplexes may play a role in specifying TADs and influencing 3D genome organization.
• Interactions between lncRNAs, CTCF, and repetitive elements could be key mechanisms in genome architecture regulation.