MSACL 2019 EU Abstract

Novel Glycopeptide Analysis Strategy for Prostate-Specific Antigen in Seminal Plasma of Infertile Men

Wei Wang(1), Anna Kałuza(2), Noortje de Haan(1), Jan Nouta(1), Manfred Wuhrer(1), Guinevere S.M. Lageveen-Kammeijer(1)
(1) Center for Proteomics and Metabolomics , Leiden University Medical Center, Netherlands (2) Department of Chemistry and Immunochemistry, Wrocław Medical University, Poland

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Wei Wang (Presenter) Leiden University Medical Center

Presenter Bio: In 2014, I received my BSc degree at the College of Food Science and Engineering, Shandong Agricultural University, China followed by a MSc on Food Science and Engineering in College of Food Science and Engineering, Nanjing Agricultural University, China in 2017. My first encounter with glycans was during the master internship, where, I looked into the effects of glycosylation on bovine and human milk glycoproteins’ antibacterial functions and did structure analysis on milk N-glycans. As my interest was triggered about the complex role glycosylation plays in many different biological processes, I started my PhD at the Center of Proteomics and Metabolomics, Leiden University Medical Centet in the Netherlands. Since October 2017, I am investigating the glycosylation of prostate-specific antigen (PSA) for evaluation of its diagnostic potential in correlation with prostate cancer.

Relevant Financial Disclosures (within past 24 months) No relevant financial relationship(s) to disclose. Discussing Products? NO, presenter will NOT present educational content related to products/services of the ineligible company(ies) listed above. Conflict mitigation NOT REQUIRED.

INTRODUCTION: Glycosylation is involved in many biological processes, one of these being fertilization. For example, literature indicates that alterations in N-glycan branching, sialylation and fucosylation are observed in seminal plasma of infertile males as compared to fertile males. While a causal relationship was not established, it is hypothesized that changes in glycosylation could disturb the normal course of fertilization. One of the major proteins in seminal plasma is the glycoprotein prostate-specific antigen (PSA). It acts as serine protease to liquefy seminal fluid by digesting seminal proteins, which results in an increased sperm motility. Moreover, it also plays an important role for the breakdown of cervical mucus and allows sperm to enter the uterus. A recent study screened seminal plasma proteins and revealed an up-regulation of fucosylation in subfertile men, which could be partially attributed to PSA. However, the exact role and effects of PSA glycosylation on male infertility is not yet clear.
METHODS: Novel high-throughput PSA glycosylation analysis methods with MALDI-TOF/FTICR-MS were established, which enables the discrimination of α2,3 and α2,6-sialylated isomers. In this study, we successfully applied the method on a sample cohort (N=100) consisting of seminal plasma from infertile patients and healthy individuals. Patient samples can be subdivided into four groups: normozoospermic (normal sperm parameters but infertile), oligozoospermic (low sperm count), asthenozoospermic (low sperm motility) and oligoasthenozoospermic (low sperm count and motility). Furthermore, a well-developed CE-ESI-MS/MS method is used to characterize novel glycan structures.
RESULTS: In total, 25 and 45 glycopeptides were identified in all samples by MALDI-TOF-MS and MALDI-FTICR-MS, respectively. All glycopeptides contained the same amino acid backbone (NK) and varied in their glycan composition and/or sialic acid linkages. Interestingly, PSA N-glycans from seminal plasma showed to be highly fucosylated and sialylated. In addition, mainly complex glycans were observed followed by hybrid-type structures and high mannose-type glycans. Studying derived glycan traits, including the level of fucosylation, sialyation, LacdiNAc and different N-glycan types of PSA glycosylation, no significant differences were observed between different groups.
DISCUSSION: Preliminary results of MALDI-TOF-MS revealed no changes in the PSA N-glycosylation between fertile and infertile males of the different groups. In other words, in contrast what has been suggested by other studies, PSA might not contribute to observed glycosylation changes in total seminal plasma. However, no direct conclusions can be drawn as the data-processing of the obtained data from high resolution MALDI-FTICR-MS data is still ongoing.