Human genomic DNA is widely interspersed with i-motif structures

Area of Science:

• Genomics
• Molecular Biology
• Biochemistry

Background:

• DNA i-motif structures form in human cell nuclei and are implicated in genomic regulation.
• Previous studies demonstrated i-motif existence and distribution using techniques like immunofluorescent staining, NMR, and CUT&Tag.
• However, the precise abundance and distribution within human genomic DNA remained largely uncharacterized.

Purpose of the Study:

• To map the genome-wide abundance and distribution of DNA i-motif structures in human genomic DNA.
• To identify specific DNA sequences capable of forming i-motif structures across the genome.
• To provide a foundational resource for understanding the genomic, structural, and molecular roles of i-motif structures.

Main Methods:

• Utilized high-affinity i-motif immunoprecipitation followed by sequencing (HPIS) to map i-motifs.
• Applied HPIS to purified genomic DNA from human cell lines (MCF7, U2OS, HEK293T).
• Validated findings using biolayer interferometry and circular dichroism spectroscopy.

Main Results:

• Identified widespread distribution of i-motif forming sequences throughout the human genome.
• Found i-motif sequences to be common in genes upregulated during the G0/G1 cell cycle phases.
• Established a genome-wide map of i-motif structures.

Conclusions:

• Provided experimental evidence for the widespread formation of i-motif structures in human genomic DNA.
• Demonstrated that i-motif sequences are prevalent and associated with specific gene expression patterns.
• The study offers a valuable resource for future research into the functional significance of DNA i-motifs.