Overview

• A study in Nature Structural & Molecular Biology reports the discovery of a RAD21–STAG3 cohesin operating in dividing spermatogonial stem cells.
• Protein mapping and immunoprecipitation–mass spectrometry confirmed that RAD21 partners with STAG3 to form a distinct cohesin complex.
• Engineered spermatogonial stem cell models showed the complex establishes the characteristically weak chromatin boundaries of these cells.
• Loss of STAG3 in mice impeded spermatogonial stem cell differentiation and produced a measurable fertility defect.
• Human datasets revealed high STAG3 expression in B cells and B‑cell lymphomas, and laboratory blockade of STAG3 slowed lymphoma cell growth.