TSP50-mediated TβRII proteolysis maintains intestinal developmental and limits age-dependent susceptibility to colitis

Testis-specific protease 50 (TSP50) is essential for maintaining intestinal homeostasis, yet its biological role in orchestrating intestinal development remains to be elucidated. This study demonstrates that TSP50 deficiency significantly exacerbates age-dependent susceptibility to colitis in mice. Phenotypic analysis shows that TSP50-deficient mice exhibit abnormal intestinal development, characterized by premature differentiation of specific epithelial cell lineages during embryonic stages and premature crypt formation during the neonatal period, while the organoid-forming capacity of intestinal stem cells (ISCs) is markedly reduced in adulthood. Mechanistically, TSP50 exerts serine protease activity via its catalytic triad to target the juxtamembrane (JM) region of TGF-β receptor II (TβRII) and mediate proteolysis of its intracellular domain (ICD), thereby restraining TGF-β signaling intensity. Persistent TGF-β hyperactivation likely serves as a major contributor to the disrupted developmental timing and deteriorated organoid-forming capacity observed in TSP50-deficient mice. Importantly, Adeno-associated virus (AAV)-mediated restoration of TSP50 expression effectively suppresses aberrant TGF-β signaling and mitigates the exacerbated age-dependent susceptibility to colitis. Furthermore, clinical analysis reveals that TSP50 expression in inflammatory bowel disease (IBD) tissues is significantly and negatively correlated with both patient age and TGF-β pathway activity. Collectively, our findings suggest that TSP50 contributes to intestinal developmental progression, at least in part through modulation of TGF-β signaling activity, providing a promising molecular target for the prevention and treatment of age-related intestinal diseases.