Imaging Method Using CRISPR/dCas9 and Engineered gRNA Scaffolds Can Perturb Replication Timing at the HSPA1 Locus

Area of Science:

• Cell Biology
• Genetics
• Molecular Biology

Background:

• Visualizing specific chromosomal sites is crucial for understanding genome architecture.
• Programmable DNA-binding proteins like TAL effectors and CRISPR/dCas9, or TetO/TetR systems, are used for live-cell imaging of endogenous loci in mammalian cells.

Purpose of the Study:

• To compare the effects of different live-cell chromosome tagging methods on subnuclear positioning, adjacent gene expression, and DNA replication timing.
• To evaluate the suitability of CRISPR-based imaging for genome architecture research.

Main Methods:

• Comparison of live-cell chromosome tagging techniques, including TetO/TetR and CRISPR/dCas9-based methods.
• Assessment of subnuclear localization, gene expression of adjacent loci, and DNA replication timing after locus labeling.

Main Results:

• CRISPR-based imaging was found to potentially delay DNA replication timing and sister chromatid resolution in specific regions.
• Neither TetO/TetR nor CRISPR-based methods significantly affected the subnuclear localization of the labeled locus.
• Gene expression from loci adjacent to the labeled sites remained unaffected by both tagging methods.

Conclusions:

• CRISPR-based imaging is a viable method for live-cell chromosome tagging in genome architecture research.
• The method's potential impact on DNA replication timing should be considered for specific applications.
• CRISPR-based imaging is suitable for studies not focused on DNA replication analysis.