SRSF1 modulates the pH microenvironment of the dark nucleolar caps to restorenucleolar integrity and function

Evidence is just emerging that nucleolar proteins with characteristic electrochemical properties condense to generate a pH gradient, which serves as a key driving force for organizing the nucleolar sub-phases. Given the indispensable functionality of the nucleolus in most, if not all, cellular activities, it is vital for a cell to sense potential fluctuations in the nucleolar pH and subsequently maintain pH homeostasis.

The mechanisms by which a cell achieves this task remain poorly decoded. Here, we show that splicing factor SRSF1 is shuttled from nuclear speckle (NS) to the nucleolus during times of stress, which interrogates the nucleolar pH. SRSF1 nucleolar localization is reliant on an acidic patch.