SRSF1 modulates the dark nucleolar cap pH to restore nucleolar integrity and function.

SRSF1 regulates nucleolar cap pH to maintain nucleolar integrity, with loss impairing pH homeostasis and recovery after stress.

• Why it matters: Understanding how nucleolar pH is controlled is crucial because it influences condensate dynamics and function, especially under stress conditions that disrupt nucleolar activities.
• What they did: The study examined SRSF1's role by tracking its relocation to dark nucleolar caps under stress and analyzing its interaction with DDX18, along with testing synthetic arginine-rich peptides.
• The result: Findings reveal SRSF1's RS domain alkalizes the nucleolar microenvironment, and synthetic derivatives can protect nucleolar pH and function, offering new insights into nucleolar regulation.