Tissue O-glycan Profile Alter during Mouse Natural Aging

Age-related biochemical and physiological changes have been found in all of the body's cells, tissues, and organs, affecting the function of all body systems. Glycosylation also undergoes changes in the pathophysiological process of aging. Glycosylation, which is highly sensitive to the biochemical environment, is a common post-translational modification of proteins, with over 50% of all human proteins glycosylated. Unlike N-glycans, the research of O-glycan for aging and longevity biomarkers are more challenging owing to the absence of abroad-specificity glycosidase for the release of O-glycans from glycoproteins. In this study, O-glycans in mouse skin tissues were chemically released by reductive β-elimination and analyzed by nano-LC chip/Q-TOF mass spectrometry (Nano-LC/MS). O-glycan enrichment was dramatically improved by optimized lipid removal prior to glycan release. The 20 O-glycan compositions were found in mouse skin tissues by Nano-LC/MS, and O-glycan structures were elucidated by tandem MS. Isomer-specific glycan analysis was successfully performed by accurate mass Q-TOF MS coupled with chip-based liquid chromatography. The alteration of O-glycans during aging was monitored by quantitative analysis. Furthermore, we could identify the relative contribution of neutral, sialylated and fucosylated glycan types. Sialylation was found to be highly correlated with the aging process. Further studies with larger sample sets will help confirm the initial data and lead to more confident detection of aging biomarkers.