The increased resolution of STED at ~50 nm in our conditions, compared to confocal imaging (~250 nm), allows discrimination between ‘true’ and ‘false’ colocalization events with high level of certainty. Colocalization between INO80 foci and R-loop foci by STED was readily observed, while multiple colocalization events between INO80 and R-loops visualised by confocal were found to be separate, distinct foci when resolved by STED.
We found for all cells analysed, the R-loops colocalized with INO80 were significantly more intense, had greater volume and greater length than their non-colocalizing counterparts. These data suggest that the INO80 complex associates with the largest, most enriched, R-loop domains in the nucleus.
Prendergast L., McClurg U.L., Hristova R., Berlinguer-Palmini R., Greener S., Veitch K., Hernandez I., Pasero P., Rico D., Higgins J.M.G., Gospodinov A. & Papamichos-Chronakis M.:
Resolution of R-loops by INO80 promotes DNA replication and maintains cancer cell proliferation and viability
Nature Communications volume 11, Article number: 4534 (2020)