Long-range DNA interactions: inter-molecular G-quadruplexes and their potential biological relevance

Area of Science:

• Molecular Biology
• Genetics
• Biochemistry

Background:

• Guanine-rich DNA forms G-quadruplexes (G4s), including intra-molecular and inter-molecular (iG4) structures.
• Intra-molecular G4s are well-studied in biological contexts, while iG4s were considered unlikely to form in cells.
• The role of iG4s in cellular processes and disease remains largely unexplored.

Purpose of the Study:

• To challenge the dogma that iG4s do not form in cells.
• To report the discovery of the first human protein with high affinity and selectivity for iG4s.
• To explore the potential biological roles and implications of iG4s in neurodegenerative diseases and aging.

Main Methods:

• Protein-DNA binding assays to determine affinity and selectivity.
• Bioinformatic analysis to identify potential iG4 forming sequences.
• Literature review and discussion of existing research on G4s and neurodegenerative diseases.

Main Results:

• Discovery of the human protein CSB with picomolar affinity and selectivity for iG4s.
• Evidence suggesting that iG4 structures can form in cellular environments.
• Identification of potential links between iG4s, C9orf72 repeat expansions, and neurodegenerative diseases like ALS and FTD.

Conclusions:

• The discovery of CSB binding to iG4s necessitates a re-evaluation of their biological relevance.
• iG4s may play a significant role in cellular functions and the pathogenesis of neurodegenerative disorders.
• Targeted chemical tools are needed to further investigate the biological roles of iG4s in aging-related diseases.