Competitive binding between WSB2 and XIAP regulates O-GlcNAcase MGEA5 ubiquitination to control prospermatogonia fate

Abstract Sertoli cell-only syndrome (SCOS) represents the most severe form of non-obstructive azoospermia and is closely associated with developmental abnormalities in prospermatogonia (ProSG). However, the mechanisms governing ProSG development remain incompletely understood. Here, we demonstrate that WSB2 plays a critical regulatory role in ProSG development through a non-canonical mechanism independent of its established function as a substrate-recognition receptor for the Elongin B/C-Cullin-SOCS (ECS) E3 ubiquitin ligase complex. Wsb2 knockout ( Wsb2 KO) mice exhibited rapid depletion of ProSG and SCOS-like phenotypes. Mechanistically, loss of WSB2 led to significantly decreased expression of the O-GlcNAcase MGEA5 in ProSG, resulting in elevated O-GlcNAcylation levels and subsequent DNA double-strand break (DSB) formation. We further found that WSB2 stabilizes MGEA5 by competitively binding to it and thereby preventing its ubiquitination by the E3 ligase XIAP. Importantly, treatment with the O-GlcNAc transferase inhibitor OSMI-1 effectively restored the ProSG population in Wsb2 KO mice. Collectively, this study uncovers a previously uncharacterized non-canonical function of WSB2, a conventional ECS complex subunit, in regulating ProSG development and establishes a critical link between O-GlcNAcylation homeostasis and germ cell maintenance.