Structural and site-specific N-glycan alterations define the glycoproteomic landscape of thymic aging in rats.

Thymic aging is a hallmark of immune senescence and systemic physiological decline, yet its underlying molecular mechanisms remain incompletely understood. In this study, we performed a high-resolution glycoproteomic analysis of the aging rat thymus by integrating with quantitative global and phospho-proteome datasets. By identifying 484 upregulated and 866 downregulated site-specific N-glycans after eliminating their protein expression changes, the study revealed four major age-associated glycan feature patterns, including markedly reduced oligo-mannose glycans, significantly increased LacdiNAc glycans with a strong correlation with elevated GalNAc-binding protein MGL, predominantly upregulated Neu5Ac-modified glycopeptides along with largely downregulated Neu5Gc-modified glycopeptides occurring at distinct glycoproteins for different immune processes, as well as upregulated bisecting N-glycans with core-fucosylation (Core-IV). Aging-related glycosylation remodeling is largely driven by altered glycosylation-related enzymes, as well as modulates immune and aging-related signaling pathways. Together, these findings highlight the functional importance of glycosylation in thymic aging and establish a high-resolution molecular map of glycosylation dynamics as a valuable resource for investigating immune decline and age-related diseases.