Discovery of functional noncoding elements by digital analysis of chromatin structure

Area of Science:

• Genomics
• Molecular Biology
• Epigenetics

Background:

• Mapping cis-regulatory sequences is crucial for understanding genome function.
• Existing methods for identifying DNase I-hypersensitive sites can be labor-intensive and require validation.

Purpose of the Study:

• To develop a high-throughput, automated method for mapping DNase I-hypersensitive sites and cis-regulatory elements.
• To analyze chromatin accessibility across diverse genomic loci and investigate nuclear organization.

Main Methods:

• Developed digital analysis of chromatin structure (DACS), a quantitative methodology for mapping DNase I cutting events.
• Utilized 19/20-bp genomic DNA tags to localize individual cutting events.
• Applied a quantitative algorithm to identify statistically significant clusters of cutting events in the human genome.

Main Results:

• DACS successfully mapped approximately 257,000 tags from erythroid cells to the human genome.
• Identified known regulatory sequences and previously unrecognized functional elements.
• Demonstrated DACS's efficiency and accuracy in localizing DNase I-hypersensitive sites via in silico simulation.
• Revealed significant differences in accessibility of distant regulatory sequences, suggesting a nuclear hierarchy.

Conclusions:

• DACS provides an efficient and unbiased approach for genome-wide mapping of regulatory elements.
• The method facilitates the discovery of novel functional genomic regions.
• Findings suggest a complex nuclear organization influencing chromatin accessibility that is not detectable by conventional assays.