Phase separation of Rbpms sequesters translation elongation machinery to preserve hematopoietic stem cell function.

Rbpms phase separation sequesters translation elongation factors to maintain low protein synthesis in hematopoietic stem cells.

• Why it matters: Understanding how HSCs preserve their long-term function and quiescence is limited, hindering their in vitro expansion and clinical use. Maintaining low protein synthesis is crucial for HSC function, but the mechanisms are unclear.
• What they did: The study identified ribosome-associated proteins enriched in HSCs and MPPs, and demonstrated that Rbpms forms biomolecular condensates that slow translation elongation by sequestering elongation factors and chaperones, with Rbpms deletion increasing protein synthesis and impairing HSC function.
• The result: Findings reveal a novel mechanism of translational regulation via phase separation in HSCs, emphasizing the importance of spatial compartmentalization and translational control for maintaining HSC quiescence and function.